text: /*
     md.c : Multiple Devices driver for Linux
  	  Copyright (C) 1998, 1999, 2000 Ingo Molnar
  
       completely rewritten, based on the MD driver code from Marc Zyngier
  
     Changes:
  
     - RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
     - RAID-6 extensions by H. Peter Anvin <hpa@zytor.com>
     - boot support for linear and striped mode by Harald Hoyer <HarryH@Royal.Net>
     - kerneld support by Boris Tobotras <boris@xtalk.msk.su>
     - kmod support by: Cyrus Durgin
     - RAID0 bugfixes: Mark Anthony Lisher <markal@iname.com>
     - Devfs support by Richard Gooch <rgooch@atnf.csiro.au>
  
     - lots of fixes and improvements to the RAID1/RAID5 and generic
       RAID code (such as request based resynchronization):
  
       Neil Brown <neilb@cse.unsw.edu.au>.
  
     - persistent bitmap code
       Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2, or (at your option)
     any later version.
  
     You should have received a copy of the GNU General Public License
     (for example /usr/src/linux/COPYING); if not, write to the Free
     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
  
  #include <linux/kthread.h>
  #include <linux/blkdev.h>
  #include <linux/sysctl.h>
  #include <linux/seq_file.h>
  #include <linux/mutex.h>
  #include <linux/buffer_head.h> /* for invalidate_bdev */
  #include <linux/poll.h>
  #include <linux/ctype.h>
  #include <linux/string.h>
  #include <linux/hdreg.h>
  #include <linux/proc_fs.h>
  #include <linux/random.h>
  #include <linux/reboot.h>
  #include <linux/file.h>
  #include <linux/compat.h>
  #include <linux/delay.h>
  #include <linux/raid/md_p.h>
  #include <linux/raid/md_u.h>
  #include <linux/slab.h>
  #include "md.h"
  #include "bitmap.h"
  
  #define DEBUG 0
  #define dprintk(x...) ((void)(DEBUG && printk(x)))
  
  #ifndef MODULE
  static void autostart_arrays(int part);
  #endif
  
  /* pers_list is a list of registered personalities protected
   * by pers_lock.
   * pers_lock does extra service to protect accesses to
   * mddev->thread when the mutex cannot be held.
   */
  static LIST_HEAD(pers_list);
  static DEFINE_SPINLOCK(pers_lock);
  
  static void md_print_devices(void);
  
  static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
  static struct workqueue_struct *md_wq;
  static struct workqueue_struct *md_misc_wq;
  
  #define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); }
  
  /*
   * Default number of read corrections we'll attempt on an rdev
   * before ejecting it from the array. We divide the read error
   * count by 2 for every hour elapsed between read errors.
   */
  #define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
  /*
   * Current RAID-1,4,5 parallel reconstruction 'guaranteed speed limit'
   * is 1000 KB/sec, so the extra system load does not show up that much.
   * Increase it if you want to have more _guaranteed_ speed. Note that
   * the RAID driver will use the maximum available bandwidth if the IO
   * subsystem is idle. There is also an 'absolute maximum' reconstruction
   * speed limit - in case reconstruction slows down your system despite
   * idle IO detection.
   *
   * you can change it via /proc/sys/dev/raid/speed_limit_min and _max.
   * or /sys/block/mdX/md/sync_speed_{min,max}
   */
  
  static int sysctl_speed_limit_min = 1000;
  static int sysctl_speed_limit_max = 200000;
  static inline int speed_min(mddev_t *mddev)
  {
  	return mddev->sync_speed_min ?
  		mddev->sync_speed_min : sysctl_speed_limit_min;
  }
  
  static inline int speed_max(mddev_t *mddev)
  {
  	return mddev->sync_speed_max ?
  		mddev->sync_speed_max : sysctl_speed_limit_max;
  }
  
  static struct ctl_table_header *raid_table_header;
  
  static ctl_table raid_table[] = {
  	{
  		.procname	= "speed_limit_min",
  		.data		= &sysctl_speed_limit_min,
  		.maxlen		= sizeof(int),
  		.mode		= S_IRUGO|S_IWUSR,
  		.proc_handler	= proc_dointvec,
  	},
  	{
  		.procname	= "speed_limit_max",
  		.data		= &sysctl_speed_limit_max,
  		.maxlen		= sizeof(int),
  		.mode		= S_IRUGO|S_IWUSR,
  		.proc_handler	= proc_dointvec,
  	},
  	{ }
  };
  
  static ctl_table raid_dir_table[] = {
  	{
  		.procname	= "raid",
  		.maxlen		= 0,
  		.mode		= S_IRUGO|S_IXUGO,
  		.child		= raid_table,
  	},
  	{ }
  };
  
  static ctl_table raid_root_table[] = {
  	{
  		.procname	= "dev",
  		.maxlen		= 0,
  		.mode		= 0555,
  		.child		= raid_dir_table,
  	},
  	{  }
  };
  
  static const struct block_device_operations md_fops;
  
  static int start_readonly;
  
  /* bio_clone_mddev
   * like bio_clone, but with a local bio set
   */
  
  static void mddev_bio_destructor(struct bio *bio)
  {
  	mddev_t *mddev, **mddevp;
  
  	mddevp = (void*)bio;
  	mddev = mddevp[-1];
  
  	bio_free(bio, mddev->bio_set);
  }
  
  struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
  			    mddev_t *mddev)
  {
  	struct bio *b;
  	mddev_t **mddevp;
  
  	if (!mddev || !mddev->bio_set)
  		return bio_alloc(gfp_mask, nr_iovecs);
  
  	b = bio_alloc_bioset(gfp_mask, nr_iovecs,
  			     mddev->bio_set);
  	if (!b)
  		return NULL;
  	mddevp = (void*)b;
  	mddevp[-1] = mddev;
  	b->bi_destructor = mddev_bio_destructor;
  	return b;
  }
  EXPORT_SYMBOL_GPL(bio_alloc_mddev);
  
  struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
  			    mddev_t *mddev)
  {
  	struct bio *b;
  	mddev_t **mddevp;
  
  	if (!mddev || !mddev->bio_set)
  		return bio_clone(bio, gfp_mask);
  
  	b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs,
  			     mddev->bio_set);
  	if (!b)
  		return NULL;
  	mddevp = (void*)b;
  	mddevp[-1] = mddev;
  	b->bi_destructor = mddev_bio_destructor;
  	__bio_clone(b, bio);
  	if (bio_integrity(bio)) {
  		int ret;
  
  		ret = bio_integrity_clone(b, bio, gfp_mask, mddev->bio_set);
  
  		if (ret < 0) {
  			bio_put(b);
  			return NULL;
  		}
  	}
  
  	return b;
  }
  EXPORT_SYMBOL_GPL(bio_clone_mddev);
  
  /*
   * We have a system wide 'event count' that is incremented
   * on any 'interesting' event, and readers of /proc/mdstat
   * can use 'poll' or 'select' to find out when the event
   * count increases.
   *
   * Events are:
   *  start array, stop array, error, add device, remove device,
   *  start build, activate spare
   */
  static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
  static atomic_t md_event_count;
  void md_new_event(mddev_t *mddev)
  {
  	atomic_inc(&md_event_count);
  	wake_up(&md_event_waiters);
  }
  EXPORT_SYMBOL_GPL(md_new_event);
  
  /* Alternate version that can be called from interrupts
   * when calling sysfs_notify isn't needed.
   */
  static void md_new_event_inintr(mddev_t *mddev)
  {
  	atomic_inc(&md_event_count);
  	wake_up(&md_event_waiters);
  }
  
  /*
   * Enables to iterate over all existing md arrays
   * all_mddevs_lock protects this list.
   */
  static LIST_HEAD(all_mddevs);
  static DEFINE_SPINLOCK(all_mddevs_lock);
  
  /*
   * iterates through all used mddevs in the system.
   * We take care to grab the all_mddevs_lock whenever navigating
   * the list, and to always hold a refcount when unlocked.
   * Any code which breaks out of this loop while own
   * a reference to the current mddev and must mddev_put it.
   */
  #define for_each_mddev(mddev,tmp)					\
  									\
  	for (({ spin_lock(&all_mddevs_lock); 				\
  		tmp = all_mddevs.next;					\
  		mddev = NULL;});					\
  	     ({ if (tmp != &all_mddevs)					\
  			mddev_get(list_entry(tmp, mddev_t, all_mddevs));\
  		spin_unlock(&all_mddevs_lock);				\
  		if (mddev) mddev_put(mddev);				\
  		mddev = list_entry(tmp, mddev_t, all_mddevs);		\
  		tmp != &all_mddevs;});					\
  	     ({ spin_lock(&all_mddevs_lock);				\
  		tmp = tmp->next;})					\
  		)
  
  /* Rather than calling directly into the personality make_request function,
   * IO requests come here first so that we can check if the device is
   * being suspended pending a reconfiguration.
   * We hold a refcount over the call to ->make_request.  By the time that
   * call has finished, the bio has been linked into some internal structure
   * and so is visible to ->quiesce(), so we don't need the refcount any more.
   */
  static int md_make_request(struct request_queue *q, struct bio *bio)
  {
  	const int rw = bio_data_dir(bio);
  	mddev_t *mddev = q->queuedata;
  	int rv;
  	int cpu;
  	unsigned int sectors;
  
  	if (mddev == NULL || mddev->pers == NULL
  	    || !mddev->ready) {
  		bio_io_error(bio);
  		return 0;
  	}
  	if (mddev->ro == 1 && unlikely(rw == WRITE)) {
  		bio_endio(bio, bio_sectors(bio) == 0 ? 0 : -EROFS);
  		return 0;
  	}
  	smp_rmb(); /* Ensure implications of  'active' are visible */
  	rcu_read_lock();
  	if (mddev->suspended) {
  		DEFINE_WAIT(__wait);
  		for (;;) {
  			prepare_to_wait(&mddev->sb_wait, &__wait,
  					TASK_UNINTERRUPTIBLE);
  			if (!mddev->suspended)
  				break;
  			rcu_read_unlock();
  			schedule();
  			rcu_read_lock();
  		}
  		finish_wait(&mddev->sb_wait, &__wait);
  	}
  	atomic_inc(&mddev->active_io);
  	rcu_read_unlock();
  
  	/*
  	 * save the sectors now since our bio can
  	 * go away inside make_request
  	 */
  	sectors = bio_sectors(bio);
  	rv = mddev->pers->make_request(mddev, bio);
  
  	cpu = part_stat_lock();
  	part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
  	part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
  	part_stat_unlock();
  
  	if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
  		wake_up(&mddev->sb_wait);
  
  	return rv;
  }
  
  /* mddev_suspend makes sure no new requests are submitted
   * to the device, and that any requests that have been submitted
   * are completely handled.
   * Once ->stop is called and completes, the module will be completely
   * unused.
   */
  void mddev_suspend(mddev_t *mddev)
  {
  	BUG_ON(mddev->suspended);
  	mddev->suspended = 1;
  	synchronize_rcu();
  	wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
  	mddev->pers->quiesce(mddev, 1);
  
  	del_timer_sync(&mddev->safemode_timer);
  }
  EXPORT_SYMBOL_GPL(mddev_suspend);
  
  void mddev_resume(mddev_t *mddev)
  {
  	mddev->suspended = 0;
  	wake_up(&mddev->sb_wait);
  	mddev->pers->quiesce(mddev, 0);
  
  	md_wakeup_thread(mddev->thread);
  	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
  }
  EXPORT_SYMBOL_GPL(mddev_resume);
  
  int mddev_congested(mddev_t *mddev, int bits)
  {
  	return mddev->suspended;
  }
  EXPORT_SYMBOL(mddev_congested);
  
  /*
   * Generic flush handling for md
   */
  
  static void md_end_flush(struct bio *bio, int err)
  {
  	mdk_rdev_t *rdev = bio->bi_private;
  	mddev_t *mddev = rdev->mddev;
  
  	rdev_dec_pending(rdev, mddev);
  
  	if (atomic_dec_and_test(&mddev->flush_pending)) {
  		/* The pre-request flush has finished */
  		queue_work(md_wq, &mddev->flush_work);
  	}
  	bio_put(bio);
  }
  
  static void md_submit_flush_data(struct work_struct *ws);
  
  static void submit_flushes(struct work_struct *ws)
  {
  	mddev_t *mddev = container_of(ws, mddev_t, flush_work);
  	mdk_rdev_t *rdev;
  
  	INIT_WORK(&mddev->flush_work, md_submit_flush_data);
  	atomic_set(&mddev->flush_pending, 1);
  	rcu_read_lock();
  	list_for_each_entry_rcu(rdev, &mddev->disks, same_set)
  		if (rdev->raid_disk >= 0 &&
  		    !test_bit(Faulty, &rdev->flags)) {
  			/* Take two references, one is dropped
  			 * when request finishes, one after
  			 * we reclaim rcu_read_lock
  			 */
  			struct bio *bi;
  			atomic_inc(&rdev->nr_pending);
  			atomic_inc(&rdev->nr_pending);
  			rcu_read_unlock();
  			bi = bio_alloc_mddev(GFP_NOIO, 0, mddev);
  			bi->bi_end_io = md_end_flush;
  			bi->bi_private = rdev;
  			bi->bi_bdev = rdev->bdev;
  			atomic_inc(&mddev->flush_pending);
  			submit_bio(WRITE_FLUSH, bi);
  			rcu_read_lock();
  			rdev_dec_pending(rdev, mddev);
  		}
  	rcu_read_unlock();
  	if (atomic_dec_and_test(&mddev->flush_pending))
  		queue_work(md_wq, &mddev->flush_work);
  }
  
  static void md_submit_flush_data(struct work_struct *ws)
  {
  	mddev_t *mddev = container_of(ws, mddev_t, flush_work);
  	struct bio *bio = mddev->flush_bio;
  
  	if (bio->bi_size == 0)
  		/* an empty barrier - all done */
  		bio_endio(bio, 0);
  	else {
  		bio->bi_rw &= ~REQ_FLUSH;
  		if (mddev->pers->make_request(mddev, bio))
  			generic_make_request(bio);
  	}
  
  	mddev->flush_bio = NULL;
  	wake_up(&mddev->sb_wait);
  }
  
  void md_flush_request(mddev_t *mddev, struct bio *bio)
  {
  	spin_lock_irq(&mddev->write_lock);
  	wait_event_lock_irq(mddev->sb_wait,
  			    !mddev->flush_bio,
  			    mddev->write_lock, /*nothing*/);
  	mddev->flush_bio = bio;
  	spin_unlock_irq(&mddev->write_lock);
  
  	INIT_WORK(&mddev->flush_work, submit_flushes);
  	queue_work(md_wq, &mddev->flush_work);
  }
  EXPORT_SYMBOL(md_flush_request);
  
  /* Support for plugging.
   * This mirrors the plugging support in request_queue, but does not
   * require having a whole queue or request structures.
   * We allocate an md_plug_cb for each md device and each thread it gets
   * plugged on.  This links tot the private plug_handle structure in the
   * personality data where we keep a count of the number of outstanding
   * plugs so other code can see if a plug is active.
   */
  struct md_plug_cb {
  	struct blk_plug_cb cb;
  	mddev_t *mddev;
  };
  
  static void plugger_unplug(struct blk_plug_cb *cb)
  {
  	struct md_plug_cb *mdcb = container_of(cb, struct md_plug_cb, cb);
  	if (atomic_dec_and_test(&mdcb->mddev->plug_cnt))
  		md_wakeup_thread(mdcb->mddev->thread);
  	kfree(mdcb);
  }
  
  /* Check that an unplug wakeup will come shortly.
   * If not, wakeup the md thread immediately
   */
  int mddev_check_plugged(mddev_t *mddev)
  {
  	struct blk_plug *plug = current->plug;
  	struct md_plug_cb *mdcb;
  
  	if (!plug)
  		return 0;
  
  	list_for_each_entry(mdcb, &plug->cb_list, cb.list) {
  		if (mdcb->cb.callback == plugger_unplug &&
  		    mdcb->mddev == mddev) {
  			/* Already on the list, move to top */
  			if (mdcb != list_first_entry(&plug->cb_list,
  						    struct md_plug_cb,
  						    cb.list))
  				list_move(&mdcb->cb.list, &plug->cb_list);
  			return 1;
  		}
  	}
  	/* Not currently on the callback list */
  	mdcb = kmalloc(sizeof(*mdcb), GFP_ATOMIC);
  	if (!mdcb)
  		return 0;
  
  	mdcb->mddev = mddev;
  	mdcb->cb.callback = plugger_unplug;
  	atomic_inc(&mddev->plug_cnt);
  	list_add(&mdcb->cb.list, &plug->cb_list);
  	return 1;
  }
  EXPORT_SYMBOL_GPL(mddev_check_plugged);
  
  static inline mddev_t *mddev_get(mddev_t *mddev)
  {
  	atomic_inc(&mddev->active);
  	return mddev;
  }
  
  static void mddev_delayed_delete(struct work_struct *ws);
  
  static void mddev_put(mddev_t *mddev)
  {
  	struct bio_set *bs = NULL;
  
  	if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
  		return;
  	if (!mddev->raid_disks && list_empty(&mddev->disks) &&
  	    mddev->ctime == 0 && !mddev->hold_active) {
  		/* Array is not configured at all, and not held active,
  		 * so destroy it */
  		list_del(&mddev->all_mddevs);
  		bs = mddev->bio_set;
  		mddev->bio_set = NULL;
  		if (mddev->gendisk) {
  			/* We did a probe so need to clean up.  Call
  			 * queue_work inside the spinlock so that
  			 * flush_workqueue() after mddev_find will
  			 * succeed in waiting for the work to be done.
  			 */
  			INIT_WORK(&mddev->del_work, mddev_delayed_delete);
  			queue_work(md_misc_wq, &mddev->del_work);
  		} else
  			kfree(mddev);
  	}
  	spin_unlock(&all_mddevs_lock);
  	if (bs)
  		bioset_free(bs);
  }
  
  void mddev_init(mddev_t *mddev)
  {
  	mutex_init(&mddev->open_mutex);
  	mutex_init(&mddev->reconfig_mutex);
  	mutex_init(&mddev->bitmap_info.mutex);
  	INIT_LIST_HEAD(&mddev->disks);
  	INIT_LIST_HEAD(&mddev->all_mddevs);
  	init_timer(&mddev->safemode_timer);
  	atomic_set(&mddev->active, 1);
  	atomic_set(&mddev->openers, 0);
  	atomic_set(&mddev->active_io, 0);
  	atomic_set(&mddev->plug_cnt, 0);
  	spin_lock_init(&mddev->write_lock);
  	atomic_set(&mddev->flush_pending, 0);
  	init_waitqueue_head(&mddev->sb_wait);
  	init_waitqueue_head(&mddev->recovery_wait);
  	mddev->reshape_position = MaxSector;
  	mddev->resync_min = 0;
  	mddev->resync_max = MaxSector;
  	mddev->level = LEVEL_NONE;
  }
  EXPORT_SYMBOL_GPL(mddev_init);
  
  static mddev_t * mddev_find(dev_t unit)
  {
  	mddev_t *mddev, *new = NULL;
  
  	if (unit && MAJOR(unit) != MD_MAJOR)
  		unit &= ~((1<<MdpMinorShift)-1);
  
   retry:
  	spin_lock(&all_mddevs_lock);
  
  	if (unit) {
  		list_for_each_entry(mddev, &all_mddevs, all_mddevs)
  			if (mddev->unit == unit) {
  				mddev_get(mddev);
  				spin_unlock(&all_mddevs_lock);
  				kfree(new);
  				return mddev;
  			}
  
  		if (new) {
  			list_add(&new->all_mddevs, &all_mddevs);
  			spin_unlock(&all_mddevs_lock);
  			new->hold_active = UNTIL_IOCTL;
  			return new;
  		}
  	} else if (new) {
  		/* find an unused unit number */
  		static int next_minor = 512;
  		int start = next_minor;
  		int is_free = 0;
  		int dev = 0;
  		while (!is_free) {
  			dev = MKDEV(MD_MAJOR, next_minor);
  			next_minor++;
  			if (next_minor > MINORMASK)
  				next_minor = 0;
  			if (next_minor == start) {
  				/* Oh dear, all in use. */
  				spin_unlock(&all_mddevs_lock);
  				kfree(new);
  				return NULL;
  			}
  
  			is_free = 1;
  			list_for_each_entry(mddev, &all_mddevs, all_mddevs)
  				if (mddev->unit == dev) {
  					is_free = 0;
  					break;
  				}
  		}
  		new->unit = dev;
  		new->md_minor = MINOR(dev);
  		new->hold_active = UNTIL_STOP;
  		list_add(&new->all_mddevs, &all_mddevs);
  		spin_unlock(&all_mddevs_lock);
  		return new;
  	}
  	spin_unlock(&all_mddevs_lock);
  
  	new = kzalloc(sizeof(*new), GFP_KERNEL);
  	if (!new)
  		return NULL;
  
  	new->unit = unit;
  	if (MAJOR(unit) == MD_MAJOR)
  		new->md_minor = MINOR(unit);
  	else
  		new->md_minor = MINOR(unit) >> MdpMinorShift;
  
  	mddev_init(new);
  
  	goto retry;
  }
  
  static inline int mddev_lock(mddev_t * mddev)
  {
  	return mutex_lock_interruptible(&mddev->reconfig_mutex);
  }
  
  static inline int mddev_is_locked(mddev_t *mddev)
  {
  	return mutex_is_locked(&mddev->reconfig_mutex);
  }
  
  static inline int mddev_trylock(mddev_t * mddev)
  {
  	return mutex_trylock(&mddev->reconfig_mutex);
  }
  
  static struct attribute_group md_redundancy_group;
  
  static void mddev_unlock(mddev_t * mddev)
  {
  	if (mddev->to_remove) {
  		/* These cannot be removed under reconfig_mutex as
  		 * an access to the files will try to take reconfig_mutex
  		 * while holding the file unremovable, which leads to
  		 * a deadlock.
  		 * So hold set sysfs_active while the remove in happeing,
  		 * and anything else which might set ->to_remove or my
  		 * otherwise change the sysfs namespace will fail with
  		 * -EBUSY if sysfs_active is still set.
  		 * We set sysfs_active under reconfig_mutex and elsewhere
  		 * test it under the same mutex to ensure its correct value
  		 * is seen.
  		 */
  		struct attribute_group *to_remove = mddev->to_remove;
  		mddev->to_remove = NULL;
  		mddev->sysfs_active = 1;
  		mutex_unlock(&mddev->reconfig_mutex);
  
  		if (mddev->kobj.sd) {
  			if (to_remove != &md_redundancy_group)
  				sysfs_remove_group(&mddev->kobj, to_remove);
  			if (mddev->pers == NULL ||
  			    mddev->pers->sync_request == NULL) {
  				sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
  				if (mddev->sysfs_action)
  					sysfs_put(mddev->sysfs_action);
  				mddev->sysfs_action = NULL;
  			}
  		}
  		mddev->sysfs_active = 0;
  	} else
  		mutex_unlock(&mddev->reconfig_mutex);
  
  	/* was we've dropped the mutex we need a spinlock to
  	 * make sur the thread doesn't disappear
  	 */
  	spin_lock(&pers_lock);
  	md_wakeup_thread(mddev->thread);
  	spin_unlock(&pers_lock);
  }
  
  static mdk_rdev_t * find_rdev_nr(mddev_t *mddev, int nr)
  {
  	mdk_rdev_t *rdev;
  
  	list_for_each_entry(rdev, &mddev->disks, same_set)
  		if (rdev->desc_nr == nr)
  			return rdev;
  
  	return NULL;
  }
  
  static mdk_rdev_t * find_rdev(mddev_t * mddev, dev_t dev)
  {
  	mdk_rdev_t *rdev;
  
  	list_for_each_entry(rdev, &mddev->disks, same_set)
  		if (rdev->bdev->bd_dev == dev)
  			return rdev;
  
  	return NULL;
  }
  
  static struct mdk_personality *find_pers(int level, char *clevel)
  {
  	struct mdk_personality *pers;
  	list_for_each_entry(pers, &pers_list, list) {
  		if (level != LEVEL_NONE && pers->level == level)
  			return pers;
  		if (strcmp(pers->name, clevel)==0)
  			return pers;
  	}
  	return NULL;
  }
  
  /* return the offset of the super block in 512byte sectors */
  static inline sector_t calc_dev_sboffset(mdk_rdev_t *rdev)
  {
  	sector_t num_sectors = i_size_read(rdev->bdev->bd_inode) / 512;
  	return MD_NEW_SIZE_SECTORS(num_sectors);
  }
  
  static int alloc_disk_sb(mdk_rdev_t * rdev)
  {
  	if (rdev->sb_page)
  		MD_BUG();
  
  	rdev->sb_page = alloc_page(GFP_KERNEL);
  	if (!rdev->sb_page) {
  		printk(KERN_ALERT "md: out of memory.\n");
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  static void free_disk_sb(mdk_rdev_t * rdev)
  {
  	if (rdev->sb_page) {
  		put_page(rdev->sb_page);
  		rdev->sb_loaded = 0;
  		rdev->sb_page = NULL;
  		rdev->sb_start = 0;
  		rdev->sectors = 0;
  	}
  }
  
  static void super_written(struct bio *bio, int error)
  {
  	mdk_rdev_t *rdev = bio->bi_private;
  	mddev_t *mddev = rdev->mddev;
  
  	if (error || !test_bit(BIO_UPTODATE, &bio->bi_flags)) {
  		printk("md: super_written gets error=%d, uptodate=%d\n",
  		       error, test_bit(BIO_UPTODATE, &bio->bi_flags));
  		WARN_ON(test_bit(BIO_UPTODATE, &bio->bi_flags));
  		md_error(mddev, rdev);
  	}
  
  	if (atomic_dec_and_test(&mddev->pending_writes))
  		wake_up(&mddev->sb_wait);
  	bio_put(bio);
  }
  
  void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
  		   sector_t sector, int size, struct page *page)
  {
  	/* write first size bytes of page to sector of rdev
  	 * Increment mddev->pending_writes before returning
  	 * and decrement it on completion, waking up sb_wait
  	 * if zero is reached.
  	 * If an error occurred, call md_error
  	 */
  	struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, mddev);
  
  	bio->bi_bdev = rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev;
  	bio->bi_sector = sector;
  	bio_add_page(bio, page, size, 0);
  	bio->bi_private = rdev;
  	bio->bi_end_io = super_written;
  
  	atomic_inc(&mddev->pending_writes);
  	submit_bio(REQ_WRITE | REQ_SYNC | REQ_FLUSH | REQ_FUA, bio);
  }
  
  void md_super_wait(mddev_t *mddev)
  {
  	/* wait for all superblock writes that were scheduled to complete */
  	DEFINE_WAIT(wq);
  	for(;;) {
  		prepare_to_wait(&mddev->sb_wait, &wq, TASK_UNINTERRUPTIBLE);
  		if (atomic_read(&mddev->pending_writes)==0)
  			break;
  		schedule();
  	}
  	finish_wait(&mddev->sb_wait, &wq);
  }
  
  static void bi_complete(struct bio *bio, int error)
  {
  	complete((struct completion*)bio->bi_private);
  }
  
  int sync_page_io(mdk_rdev_t *rdev, sector_t sector, int size,
  		 struct page *page, int rw, bool metadata_op)
  {
  	struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, rdev->mddev);
  	struct completion event;
  	int ret;
  
  	rw |= REQ_SYNC;
  
  	bio->bi_bdev = (metadata_op && rdev->meta_bdev) ?
  		rdev->meta_bdev : rdev->bdev;
  	if (metadata_op)
  		bio->bi_sector = sector + rdev->sb_start;
  	else
  		bio->bi_sector = sector + rdev->data_offset;
  	bio_add_page(bio, page, size, 0);
  	init_completion(&event);
  	bio->bi_private = &event;
  	bio->bi_end_io = bi_complete;
  	submit_bio(rw, bio);
  	wait_for_completion(&event);
  
  	ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
  	bio_put(bio);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(sync_page_io);
  
  static int read_disk_sb(mdk_rdev_t * rdev, int size)
  {
  	char b[BDEVNAME_SIZE];
  	if (!rdev->sb_page) {
  		MD_BUG();
  		return -EINVAL;
  	}
  	if (rdev->sb_loaded)
  		return 0;
  
  	if (!sync_page_io(rdev, 0, size, rdev->sb_page, READ, true))
  		goto fail;
  	rdev->sb_loaded = 1;
  	return 0;
  
  fail:
  	printk(KERN_WARNING "md: disabled device %s, could not read superblock.\n",
  		bdevname(rdev->bdev,b));
  	return -EINVAL;
  }
  
  static int uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
  {
  	return 	sb1->set_uuid0 == sb2->set_uuid0 &&
  		sb1->set_uuid1 == sb2->set_uuid1 &&
  		sb1->set_uuid2 == sb2->set_uuid2 &&
  		sb1->set_uuid3 == sb2->set_uuid3;
  }
  
  static int sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
  {
  	int ret;
  	mdp_super_t *tmp1, *tmp2;
  
  	tmp1 = kmalloc(sizeof(*tmp1),GFP_KERNEL);
  	tmp2 = kmalloc(sizeof(*tmp2),GFP_KERNEL);
  
  	if (!tmp1 || !tmp2) {
  		ret = 0;
  		printk(KERN_INFO "md.c sb_equal(): failed to allocate memory!\n");
  		goto abort;
  	}
  
  	*tmp1 = *sb1;
  	*tmp2 = *sb2;
  
  	/*
  	 * nr_disks is not constant
  	 */
  	tmp1->nr_disks = 0;
  	tmp2->nr_disks = 0;
  
  	ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
  abort:
  	kfree(tmp1);
  	kfree(tmp2);
  	return ret;
  }
  
  static u32 md_csum_fold(u32 csum)
  {
  	csum = (csum & 0xffff) + (csum >> 16);
  	return (csum & 0xffff) + (csum >> 16);
  }
  
  static unsigned int calc_sb_csum(mdp_super_t * sb)
  {
  	u64 newcsum = 0;
  	u32 *sb32 = (u32*)sb;
  	int i;
  	unsigned int disk_csum, csum;
  
  	disk_csum = sb->sb_csum;
  	sb->sb_csum = 0;
  
  	for (i = 0; i < MD_SB_BYTES/4 ; i++)
  		newcsum += sb32[i];
  	csum = (newcsum & 0xffffffff) + (newcsum>>32);
  
  #ifdef CONFIG_ALPHA
  	/* This used to use csum_partial, which was wrong for several
  	 * reasons including that different results are returned on
  	 * different architectures.  It isn't critical that we get exactly
  	 * the same return value as before (we always csum_fold before
  	 * testing, and that removes any differences).  However as we
  	 * know that csum_partial always returned a 16bit value on
  	 * alphas, do a fold to maximise conformity to previous behaviour.
  	 */
  	sb->sb_csum = md_csum_fold(disk_csum);
  #else
  	sb->sb_csum = disk_csum;
  #endif
  	return csum;
  }
  
  /*
   * Handle superblock details.
   * We want to be able to handle multiple superblock formats
   * so we have a common interface to them all, and an array of
   * different handlers.
   * We rely on user-space to write the initial superblock, and support
   * reading and updating of superblocks.
   * Interface methods are:
   *   int load_super(mdk_rdev_t *dev, mdk_rdev_t *refdev, int minor_version)
   *      loads and validates a superblock on dev.
   *      if refdev != NULL, compare superblocks on both devices
   *    Return:
   *      0 - dev has a superblock that is compatible with refdev
   *      1 - dev has a superblock that is compatible and newer than refdev
   *          so dev should be used as the refdev in future
   *     -EINVAL superblock incompatible or invalid
   *     -othererror e.g. -EIO
   *
   *   int validate_super(mddev_t *mddev, mdk_rdev_t *dev)
   *      Verify that dev is acceptable into mddev.
   *       The first time, mddev->raid_disks will be 0, and data from
   *       dev should be merged in.  Subsequent calls check that dev
   *       is new enough.  Return 0 or -EINVAL
   *
   *   void sync_super(mddev_t *mddev, mdk_rdev_t *dev)
   *     Update the superblock for rdev with data in mddev
   *     This does not write to disc.
   *
   */
  
  struct super_type  {
  	char		    *name;
  	struct module	    *owner;
  	int		    (*load_super)(mdk_rdev_t *rdev, mdk_rdev_t *refdev,
  					  int minor_version);
  	int		    (*validate_super)(mddev_t *mddev, mdk_rdev_t *rdev);
  	void		    (*sync_super)(mddev_t *mddev, mdk_rdev_t *rdev);
  	unsigned long long  (*rdev_size_change)(mdk_rdev_t *rdev,
  						sector_t num_sectors);
  };
  
  /*
   * Check that the given mddev has no bitmap.
   *
   * This function is called from the run method of all personalities that do not
   * support bitmaps. It prints an error message and returns non-zero if mddev
   * has a bitmap. Otherwise, it returns 0.
   *
   */
  int md_check_no_bitmap(mddev_t *mddev)
  {
  	if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
  		return 0;
  	printk(KERN_ERR "%s: bitmaps are not supported for %s\n",
  		mdname(mddev), mddev->pers->name);
  	return 1;
  }
  EXPORT_SYMBOL(md_check_no_bitmap);
  
  /*
   * load_super for 0.90.0
   */
  static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
  {
  	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
  	mdp_super_t *sb;
  	int ret;
  
  	/*
  	 * Calculate the position of the superblock (512byte sectors),
  	 * it's at the end of the disk.
  	 *
  	 * It also happens to be a multiple of 4Kb.
  	 */
  	rdev->sb_start = calc_dev_sboffset(rdev);
  
  	ret = read_disk_sb(rdev, MD_SB_BYTES);
  	if (ret) return ret;
  
  	ret = -EINVAL;
  
  	bdevname(rdev->bdev, b);
  	sb = (mdp_super_t*)page_address(rdev->sb_page);
  
  	if (sb->md_magic != MD_SB_MAGIC) {
  		printk(KERN_ERR "md: invalid raid superblock magic on %s\n",
  		       b);
  		goto abort;
  	}
  
  	if (sb->major_version != 0 ||
  	    sb->minor_version < 90 ||
  	    sb->minor_version > 91) {
  		printk(KERN_WARNING "Bad version number %d.%d on %s\n",
  			sb->major_version, sb->minor_version,
  			b);
  		goto abort;
  	}
  
  	if (sb->raid_disks <= 0)
  		goto abort;
  
  	if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
  		printk(KERN_WARNING "md: invalid superblock checksum on %s\n",
  			b);
  		goto abort;
  	}
  
  	rdev->preferred_minor = sb->md_minor;
  	rdev->data_offset = 0;
  	rdev->sb_size = MD_SB_BYTES;
  
  	if (sb->level == LEVEL_MULTIPATH)
  		rdev->desc_nr = -1;
  	else
  		rdev->desc_nr = sb->this_disk.number;
  
  	if (!refdev) {
  		ret = 1;
  	} else {
  		__u64 ev1, ev2;
  		mdp_super_t *refsb = (mdp_super_t*)page_address(refdev->sb_page);
  		if (!uuid_equal(refsb, sb)) {
  			printk(KERN_WARNING "md: %s has different UUID to %s\n",
  				b, bdevname(refdev->bdev,b2));
  			goto abort;
  		}
  		if (!sb_equal(refsb, sb)) {
  			printk(KERN_WARNING "md: %s has same UUID"
  			       " but different superblock to %s\n",
  			       b, bdevname(refdev->bdev, b2));
  			goto abort;
  		}
  		ev1 = md_event(sb);
  		ev2 = md_event(refsb);
  		if (ev1 > ev2)
  			ret = 1;
  		else
  			ret = 0;
  	}
  	rdev->sectors = rdev->sb_start;
  	/* Limit to 4TB as metadata cannot record more than that.
  	 * (not needed for Linear and RAID0 as metadata doesn't
  	 * record this size)
  	 */
  	if (rdev->sectors >= (2ULL << 32) && sb->level >= 1)
  		rdev->sectors = (2ULL << 32) - 2;
  
  	if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1)
  		/* "this cannot possibly happen" ... */
  		ret = -EINVAL;
  
   abort:
  	return ret;
  }
  
  /*
   * validate_super for 0.90.0
   */
  static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
  {
  	mdp_disk_t *desc;
  	mdp_super_t *sb = (mdp_super_t *)page_address(rdev->sb_page);
  	__u64 ev1 = md_event(sb);
  
  	rdev->raid_disk = -1;
  	clear_bit(Faulty, &rdev->flags);
  	clear_bit(In_sync, &rdev->flags);
  	clear_bit(WriteMostly, &rdev->flags);
  
  	if (mddev->raid_disks == 0) {
  		mddev->major_version = 0;
  		mddev->minor_version = sb->minor_version;
  		mddev->patch_version = sb->patch_version;
  		mddev->external = 0;
  		mddev->chunk_sectors = sb->chunk_size >> 9;
  		mddev->ctime = sb->ctime;
  		mddev->utime = sb->utime;
  		mddev->level = sb->level;
  		mddev->clevel[0] = 0;
  		mddev->layout = sb->layout;
  		mddev->raid_disks = sb->raid_disks;
  		mddev->dev_sectors = ((sector_t)sb->size) * 2;
  		mddev->events = ev1;
  		mddev->bitmap_info.offset = 0;
  		mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
  
  		if (mddev->minor_version >= 91) {
  			mddev->reshape_position = sb->reshape_position;
  			mddev->delta_disks = sb->delta_disks;
  			mddev->new_level = sb->new_level;
  			mddev->new_layout = sb->new_layout;
  			mddev->new_chunk_sectors = sb->new_chunk >> 9;
  		} else {
  			mddev->reshape_position = MaxSector;
  			mddev->delta_disks = 0;
  			mddev->new_level = mddev->level;
  			mddev->new_layout = mddev->layout;
  			mddev->new_chunk_sectors = mddev->chunk_sectors;
  		}
  
  		if (sb->state & (1<<MD_SB_CLEAN))
  			mddev->recovery_cp = MaxSector;
  		else {
  			if (sb->events_hi == sb->cp_events_hi &&
  				sb->events_lo == sb->cp_events_lo) {
  				mddev->recovery_cp = sb->recovery_cp;
  			} else
  				mddev->recovery_cp = 0;
  		}
  
  		memcpy(mddev->uuid+0, &sb->set_uuid0, 4);
  		memcpy(mddev->uuid+4, &sb->set_uuid1, 4);
  		memcpy(mddev->uuid+8, &sb->set_uuid2, 4);
  		memcpy(mddev->uuid+12,&sb->set_uuid3, 4);
  
  		mddev->max_disks = MD_SB_DISKS;
  
  		if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
  		    mddev->bitmap_info.file == NULL)
  			mddev->bitmap_info.offset =
  				mddev->bitmap_info.default_offset;
  
  	} else if (mddev->pers == NULL) {
  		/* Insist on good event counter while assembling, except
  		 * for spares (which don't need an event count) */
  		++ev1;
  		if (sb->disks[rdev->desc_nr].state & (
  			    (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
  			if (ev1 < mddev->events)
  				return -EINVAL;
  	} else if (mddev->bitmap) {
  		/* if adding to array with a bitmap, then we can accept an
  		 * older device ... but not too old.
  		 */
  		if (ev1 < mddev->bitmap->events_cleared)
  			return 0;
  	} else {
  		if (ev1 < mddev->events)
  			/* just a hot-add of a new device, leave raid_disk at -1 */
  			return 0;
  	}
  
  	if (mddev->level != LEVEL_MULTIPATH) {
  		desc = sb->disks + rdev->desc_nr;
  
  		if (desc->state & (1<<MD_DISK_FAULTY))
  			set_bit(Faulty, &rdev->flags);
  		else if (desc->state & (1<<MD_DISK_SYNC) /* &&
  			    desc->raid_disk < mddev->raid_disks */) {
  			set_bit(In_sync, &rdev->flags);
  			rdev->raid_disk = desc->raid_disk;
  		} else if (desc->state & (1<<MD_DISK_ACTIVE)) {
  			/* active but not in sync implies recovery up to
  			 * reshape position.  We don't know exactly where
  			 * that is, so set to zero for now */
  			if (mddev->minor_version >= 91) {
  				rdev->recovery_offset = 0;
  				rdev->raid_disk = desc->raid_disk;
  			}
  		}
  		if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
  			set_bit(WriteMostly, &rdev->flags);
  	} else /* MULTIPATH are always insync */
  		set_bit(In_sync, &rdev->flags);
  	return 0;
  }
  
  /*
   * sync_super for 0.90.0
   */
  static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
  {
  	mdp_super_t *sb;
  	mdk_rdev_t *rdev2;
  	int next_spare = mddev->raid_disks;
  
  	/* make rdev->sb match mddev data..
  	 *
  	 * 1/ zero out disks
  	 * 2/ Add info for each disk, keeping track of highest desc_nr (next_spare);
  	 * 3/ any empty disks < next_spare become removed
  	 *
  	 * disks[0] gets initialised to REMOVED because
  	 * we cannot be sure from other fields if it has
  	 * been initialised or not.
  	 */
  	int i;
  	int active=0, working=0,failed=0,spare=0,nr_disks=0;
  
  	rdev->sb_size = MD_SB_BYTES;
  
  	sb = (mdp_super_t*)page_address(rdev->sb_page);
  
  	memset(sb, 0, sizeof(*sb));
  
  	sb->md_magic = MD_SB_MAGIC;
  	sb->major_version = mddev->major_version;
  	sb->patch_version = mddev->patch_version;
  	sb->gvalid_words  = 0; /* ignored */
  	memcpy(&sb->set_uuid0, mddev->uuid+0, 4);
  	memcpy(&sb->set_uuid1, mddev->uuid+4, 4);
  	memcpy(&sb->set_uuid2, mddev->uuid+8, 4);
  	memcpy(&sb->set_uuid3, mddev->uuid+12,4);
  
  	sb->ctime = mddev->ctime;
  	sb->level = mddev->level;
  	sb->size = mddev->dev_sectors / 2;
  	sb->raid_disks = mddev->raid_disks;
  	sb->md_minor = mddev->md_minor;
  	sb->not_persistent = 0;
  	sb->utime = mddev->utime;
  	sb->state = 0;
  	sb->events_hi = (mddev->events>>32);
  	sb->events_lo = (u32)mddev->events;
  
  	if (mddev->reshape_position == MaxSector)
  		sb->minor_version = 90;
  	else {
  		sb->minor_version = 91;
  		sb->reshape_position = mddev->reshape_position;
  		sb->new_level = mddev->new_level;
  		sb->delta_disks = mddev->delta_disks;
  		sb->new_layout = mddev->new_layout;
  		sb->new_chunk = mddev->new_chunk_sectors << 9;
  	}
  	mddev->minor_version = sb->minor_version;
  	if (mddev->in_sync)
  	{
  		sb->recovery_cp = mddev->recovery_cp;
  		sb->cp_events_hi = (mddev->events>>32);
  		sb->cp_events_lo = (u32)mddev->events;
  		if (mddev->recovery_cp == MaxSector)
  			sb->state = (1<< MD_SB_CLEAN);
  	} else
  		sb->recovery_cp = 0;
  
  	sb->layout = mddev->layout;
  	sb->chunk_size = mddev->chunk_sectors << 9;
  
  	if (mddev->bitmap && mddev->bitmap_info.file == NULL)
  		sb->state |= (1<<MD_SB_BITMAP_PRESENT);
  
  	sb->disks[0].state = (1<<MD_DISK_REMOVED);
  	list_for_each_entry(rdev2, &mddev->disks, same_set) {
  		mdp_disk_t *d;
  		int desc_nr;
  		int is_active = test_bit(In_sync, &rdev2->flags);
  
  		if (rdev2->raid_disk >= 0 &&
  		    sb->minor_version >= 91)
  			/* we have nowhere to store the recovery_offset,
  			 * but if it is not below the reshape_position,
  			 * we can piggy-back on that.
  			 */
  			is_active = 1;
  		if (rdev2->raid_disk < 0 ||
  		    test_bit(Faulty, &rdev2->flags))
  			is_active = 0;
  		if (is_active)
  			desc_nr = rdev2->raid_disk;
  		else
  			desc_nr = next_spare++;
  		rdev2->desc_nr = desc_nr;
  		d = &sb->disks[rdev2->desc_nr];
  		nr_disks++;
  		d->number = rdev2->desc_nr;
  		d->major = MAJOR(rdev2->bdev->bd_dev);
  		d->minor = MINOR(rdev2->bdev->bd_dev);
  		if (is_active)
  			d->raid_disk = rdev2->raid_disk;
  		else
  			d->raid_disk = rdev2->desc_nr; /* compatibility */
  		if (test_bit(Faulty, &rdev2->flags))
  			d->state = (1<<MD_DISK_FAULTY);
  		else if (is_active) {
  			d->state = (1<<MD_DISK_ACTIVE);
  			if (test_bit(In_sync, &rdev2->flags))
  				d->state |= (1<<MD_DISK_SYNC);
  			active++;
  			working++;
  		} else {
  			d->state = 0;
  			spare++;
  			working++;
  		}
  		if (test_bit(WriteMostly, &rdev2->flags))
  			d->state |= (1<<MD_DISK_WRITEMOSTLY);
  	}
  	/* now set the "removed" and "faulty" bits on any missing devices */
  	for (i=0 ; i < mddev->raid_disks ; i++) {
  		mdp_disk_t *d = &sb->disks[i];
  		if (d->state == 0 && d->number == 0) {
  			d->number = i;
  			d->raid_disk = i;
  			d->state = (1<<MD_DISK_REMOVED);
  			d->state |= (1<<MD_DISK_FAULTY);
  			failed++;
  		}
  	}
  	sb->nr_disks = nr_disks;
  	sb->active_disks = active;
  	sb->working_disks = working;
  	sb->failed_disks = failed;
  	sb->spare_disks = spare;
  
  	sb->this_disk = sb->disks[rdev->desc_nr];
  	sb->sb_csum = calc_sb_csum(sb);
  }
  
  /*
   * rdev_size_change for 0.90.0
   */
  static unsigned long long
  super_90_rdev_size_change(mdk_rdev_t *rdev, sector_t num_sectors)
  {
  	if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
  		return 0; /* component must fit device */
  	if (rdev->mddev->bitmap_info.offset)
  		return 0; /* can't move bitmap */
  	rdev->sb_start = calc_dev_sboffset(rdev);
  	if (!num_sectors || num_sectors > rdev->sb_start)
  		num_sectors = rdev->sb_start;
  	/* Limit to 4TB as metadata cannot record more than that.
  	 * 4TB == 2^32 KB, or 2*2^32 sectors.
  	 */
  	if (num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1)
  		num_sectors = (2ULL << 32) - 2;
  	md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
  		       rdev->sb_page);
  	md_super_wait(rdev->mddev);
  	return num_sectors;
  }
  
  /*
   * version 1 superblock
   */
  
  static __le32 calc_sb_1_csum(struct mdp_superblock_1 * sb)
  {
  	__le32 disk_csum;
  	u32 csum;
  	unsigned long long newcsum;
  	int size = 256 + le32_to_cpu(sb->max_dev)*2;
  	__le32 *isuper = (__le32*)sb;
  	int i;
  
  	disk_csum = sb->sb_csum;
  	sb->sb_csum = 0;
  	newcsum = 0;
  	for (i=0; size>=4; size -= 4 )
  		newcsum += le32_to_cpu(*isuper++);
  
  	if (size == 2)
  		newcsum += le16_to_cpu(*(__le16*) isuper);
  
  	csum = (newcsum & 0xffffffff) + (newcsum >> 32);
  	sb->sb_csum = disk_csum;
  	return cpu_to_le32(csum);
  }
  
  static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version)
  {
  	struct mdp_superblock_1 *sb;
  	int ret;
  	sector_t sb_start;
  	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
  	int bmask;
  
  	/*
  	 * Calculate the position of the superblock in 512byte sectors.
  	 * It is always aligned to a 4K boundary and
  	 * depeding on minor_version, it can be:
  	 * 0: At least 8K, but less than 12K, from end of device
  	 * 1: At start of device
  	 * 2: 4K from start of device.
  	 */
  	switch(minor_version) {
  	case 0:
  		sb_start = i_size_read(rdev->bdev->bd_inode) >> 9;
  		sb_start -= 8*2;
  		sb_start &= ~(sector_t)(4*2-1);
  		break;
  	case 1:
  		sb_start = 0;
  		break;
  	case 2:
  		sb_start = 8;
  		break;
  	default:
  		return -EINVAL;
  	}
  	rdev->sb_start = sb_start;
  
  	/* superblock is rarely larger than 1K, but it can be larger,
  	 * and it is safe to read 4k, so we do that
  	 */
  	ret = read_disk_sb(rdev, 4096);
  	if (ret) return ret;
  
  	sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
  
  	if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
  	    sb->major_version != cpu_to_le32(1) ||
  	    le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
  	    le64_to_cpu(sb->super_offset) != rdev->sb_start ||
  	    (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
  		return -EINVAL;
  
  	if (calc_sb_1_csum(sb) != sb->sb_csum) {
  		printk("md: invalid superblock checksum on %s\n",
  			bdevname(rdev->bdev,b));
  		return -EINVAL;
  	}
  	if (le64_to_cpu(sb->data_size) < 10) {
  		printk("md: data_size too small on %s\n",
  		       bdevname(rdev->bdev,b));
  		return -EINVAL;
  	}
  
  	rdev->preferred_minor = 0xffff;
  	rdev->data_offset = le64_to_cpu(sb->data_offset);
  	atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));
  
  	rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
  	bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
  	if (rdev->sb_size & bmask)
  		rdev->sb_size = (rdev->sb_size | bmask) + 1;
  
  	if (minor_version
  	    && rdev->data_offset < sb_start + (rdev->sb_size/512))
  		return -EINVAL;
  
  	if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
  		rdev->desc_nr = -1;
  	else
  		rdev->desc_nr = le32_to_cpu(sb->dev_number);
  
  	if (!refdev) {
  		ret = 1;
  	} else {
  		__u64 ev1, ev2;
  		struct mdp_superblock_1 *refsb =
  			(struct mdp_superblock_1*)page_address(refdev->sb_page);
  
  		if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
  		    sb->level != refsb->level ||
  		    sb->layout != refsb->layout ||
  		    sb->chunksize != refsb->chunksize) {
  			printk(KERN_WARNING "md: %s has strangely different"
  				" superblock to %s\n",
  				bdevname(rdev->bdev,b),
  				bdevname(refdev->bdev,b2));
  			return -EINVAL;
  		}
  		ev1 = le64_to_cpu(sb->events);
  		ev2 = le64_to_cpu(refsb->events);
  
  		if (ev1 > ev2)
  			ret = 1;
  		else
  			ret = 0;
  	}
  	if (minor_version)
  		rdev->sectors = (i_size_read(rdev->bdev->bd_inode) >> 9) -
  			le64_to_cpu(sb->data_offset);
  	else
  		rdev->sectors = rdev->sb_start;
  	if (rdev->sectors < le64_to_cpu(sb->data_size))
  		return -EINVAL;
  	rdev->sectors = le64_to_cpu(sb->data_size);
  	if (le64_to_cpu(sb->size) > rdev->sectors)
  		return -EINVAL;
  	return ret;
  }
  
  static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
  {
  	struct mdp_superblock_1 *sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
  	__u64 ev1 = le64_to_cpu(sb->events);
  
  	rdev->raid_disk = -1;
  	clear_bit(Faulty, &rdev->flags);
  	clear_bit(In_sync, &rdev->flags);
  	clear_bit(WriteMostly, &rdev->flags);
  
  	if (mddev->raid_disks == 0) {
  		mddev->major_version = 1;
  		mddev->patch_version = 0;
  		mddev->external = 0;
  		mddev->chunk_sectors = le32_to_cpu(sb->chunksize);
  		mddev->ctime = le64_to_cpu(sb->ctime) & ((1ULL << 32)-1);
  		mddev->utime = le64_to_cpu(sb->utime) & ((1ULL << 32)-1);
  		mddev->level = le32_to_cpu(sb->level);
  		mddev->clevel[0] = 0;
  		mddev->layout = le32_to_cpu(sb->layout);
  		mddev->raid_disks = le32_to_cpu(sb->raid_disks);
  		mddev->dev_sectors = le64_to_cpu(sb->size);
  		mddev->events = ev1;
  		mddev->bitmap_info.offset = 0;
  		mddev->bitmap_info.default_offset = 1024 >> 9;
  
  		mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
  		memcpy(mddev->uuid, sb->set_uuid, 16);
  
  		mddev->max_disks =  (4096-256)/2;
  
  		if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
  		    mddev->bitmap_info.file == NULL )
  			mddev->bitmap_info.offset =
  				(__s32)le32_to_cpu(sb->bitmap_offset);
  
  		if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
  			mddev->reshape_position = le64_to_cpu(sb->reshape_position);
  			mddev->delta_disks = le32_to_cpu(sb->delta_disks);
  			mddev->new_level = le32_to_cpu(sb->new_level);
  			mddev->new_layout = le32_to_cpu(sb->new_layout);
  			mddev->new_chunk_sectors = le32_to_cpu(sb->new_chunk);
  		} else {
  			mddev->reshape_position = MaxSector;
  			mddev->delta_disks = 0;
  			mddev->new_level = mddev->level;
  			mddev->new_layout = mddev->layout;
  			mddev->new_chunk_sectors = mddev->chunk_sectors;
  		}
  
  	} else if (mddev->pers == NULL) {
  		/* Insist of good event counter while assembling, except for
  		 * spares (which don't need an event count) */
  		++ev1;
  		if (rdev->desc_nr >= 0 &&
  		    rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
  		    le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < 0xfffe)
  			if (ev1 < mddev->events)
  				return -EINVAL;
  	} else if (mddev->bitmap) {
  		/* If adding to array with a bitmap, then we can accept an
  		 * older device, but not too old.
  		 */
  		if (ev1 < mddev->bitmap->events_cleared)
  			return 0;
  	} else {
  		if (ev1 < mddev->events)
  			/* just a hot-add of a new device, leave raid_disk at -1 */
  			return 0;
  	}
  	if (mddev->level != LEVEL_MULTIPATH) {
  		int role;
  		if (rdev->desc_nr < 0 ||
  		    rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
  			role = 0xffff;
  			rdev->desc_nr = -1;
  		} else
  			role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
  		switch(role) {
  		case 0xffff: /* spare */
  			break;
  		case 0xfffe: /* faulty */
  			set_bit(Faulty, &rdev->flags);
  			break;
  		default:
  			if ((le32_to_cpu(sb->feature_map) &
  			     MD_FEATURE_RECOVERY_OFFSET))
  				rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
  			else
  				set_bit(In_sync, &rdev->flags);
  			rdev->raid_disk = role;
  			break;
  		}
  		if (sb->devflags & WriteMostly1)
  			set_bit(WriteMostly, &rdev->flags);
  	} else /* MULTIPATH are always insync */
  		set_bit(In_sync, &rdev->flags);
  
  	return 0;
  }
  
  static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
  {
  	struct mdp_superblock_1 *sb;
  	mdk_rdev_t *rdev2;
  	int max_dev, i;
  	/* make rdev->sb match mddev and rdev data. */
  
  	sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);
  
  	sb->feature_map = 0;
  	sb->pad0 = 0;
  	sb->recovery_offset = cpu_to_le64(0);
  	memset(sb->pad1, 0, sizeof(sb->pad1));
  	memset(sb->pad2, 0, sizeof(sb->pad2));
  	memset(sb->pad3, 0, sizeof(sb->pad3));
  
  	sb->utime = cpu_to_le64((__u64)mddev->utime);
  	sb->events = cpu_to_le64(mddev->events);
  	if (mddev->in_sync)
  		sb->resync_offset = cpu_to_le64(mddev->recovery_cp);
  	else
  		sb->resync_offset = cpu_to_le64(0);
  
  	sb->cnt_corrected_read = cpu_to_le32(atomic_read(&rdev->corrected_errors));
  
  	sb->raid_disks = cpu_to_le32(mddev->raid_disks);
  	sb->size = cpu_to_le64(mddev->dev_sectors);
  	sb->chunksize = cpu_to_le32(mddev->chunk_sectors);
  	sb->level = cpu_to_le32(mddev->level);
  	sb->layout = cpu_to_le32(mddev->layout);
  
  	if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
  		sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
  		sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
  	}
  
  	if (rdev->raid_disk >= 0 &&
  	    !test_bit(In_sync, &rdev->flags)) {
  		sb->feature_map |=
  			cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
  		sb->recovery_offset =
  			cpu_to_le64(rdev->recovery_offset);
  	}
  
  	if (mddev->reshape_position != MaxSector) {
  		sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
  		sb->reshape_position = cpu_to_le64(mddev->reshape_position);
  		sb->new_layout = cpu_to_le32(mddev->new_layout);
  		sb->delta_disks = cpu_to_le32(mddev->delta_disks);
  		sb->new_level = cpu_to_le32(mddev->new_level);
  		sb->new_chunk = cpu_to_le32(mddev->new_chunk_sectors);
  	}
  
  	max_dev = 0;
  	list_for_each_entry(rdev2, &mddev->disks, same_set)
  		if (rdev2->desc_nr+1 > max_dev)
  			max_dev = rdev2->desc_nr+1;
  
  	if (max_dev > le32_to_cpu(sb->max_dev)) {
  		int bmask;
  		sb->max_dev = cpu_to_le32(max_dev);
  		rdev->sb_size = max_dev * 2 + 256;
  		bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
  		if (rdev->sb_size & bmask)
  			rdev->sb_size = (rdev->sb_size | bmask) + 1;
  	} else
  		max_dev = le32_to_cpu(sb->max_dev);
  
  	for (i=0; i<max_dev;i++)
  		sb->dev_roles[i] = cpu_to_le16(0xfffe);
  
  	list_for_each_entry(rdev2, &mddev->disks, same_set) {
  		i = rdev2->desc_nr;
  		if (test_bit(Faulty, &rdev2->flags))
  			sb->dev_roles[i] = cpu_to_le16(0xfffe);
  		else if (test_bit(In_sync, &rdev2->flags))
  			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
  		else if (rdev2->raid_disk >= 0)
  			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
  		else
  			sb->dev_roles[i] = cpu_to_le16(0xffff);
  	}
  
  	sb->sb_csum = calc_sb_1_csum(sb);
  }
  
  static unsigned long long
  super_1_rdev_size_change(mdk_rdev_t *rdev, sector_t num_sectors)
  {
  	struct mdp_superblock_1 *sb;
  	sector_t max_sectors;
  	if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
  		return 0; /* component must fit device */
  	if (rdev->sb_start < rdev->data_offset) {
  		/* minor versions 1 and 2; superblock before data */
  		max_sectors = i_size_read(rdev->bdev->bd_inode) >> 9;
  		max_sectors -= rdev->data_offset;
  		if (!num_sectors || num_sectors > max_sectors)
  			num_sectors = max_sectors;
  	} else if (rdev->mddev->bitmap_info.offset) {
  		/* minor version 0 with bitmap we can't move */
  		return 0;
  	} else {
  		/* minor version 0; superblock after data */
  		sector_t sb_start;
  		sb_start = (i_size_read(rdev->bdev->bd_inode) >> 9) - 8*2;
  		sb_start &= ~(sector_t)(4*2 - 1);
  		max_sectors = rdev->sectors + sb_start - rdev->sb_start;
  		if (!num_sectors || num_sectors > max_sectors)
  			num_sectors = max_sectors;
  		rdev->sb_start = sb_start;
  	}
  	sb = (struct mdp_superblock_1 *) page_address(rdev->sb_page);
  	sb->data_size = cpu_to_le64(num_sectors);
  	sb->super_offset = rdev->sb_start;
  	sb->sb_csum = calc_sb_1_csum(sb);
  	md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
  		       rdev->sb_page);
  	md_super_wait(rdev->mddev);
  	return num_sectors;
  }
  
  static struct super_type super_types[] = {
  	[0] = {
  		.name	= "0.90.0",
  		.owner	= THIS_MODULE,
  		.load_super	    = super_90_load,
  		.validate_super	    = super_90_validate,
  		.sync_super	    = super_90_sync,
  		.rdev_size_change   = super_90_rdev_size_change,
  	},
  	[1] = {
  		.name	= "md-1",
  		.owner	= THIS_MODULE,
  		.load_super	    = super_1_load,
  		.validate_super	    = super_1_validate,
  		.sync_super	    = super_1_sync,
  		.rdev_size_change   = super_1_rdev_size_change,
  	},
  };
  
  static void sync_super(mddev_t *mddev, mdk_rdev_t *rdev)
  {
  	if (mddev->sync_super) {
  		mddev->sync_super(mddev, rdev);
  		return;
  	}
  
  	BUG_ON(mddev->major_version >= ARRAY_SIZE(super_types));
  
  	super_types[mddev->major_version].sync_super(mddev, rdev);
  }
  
  static int match_mddev_units(mddev_t *mddev1, mddev_t *mddev2)
  {
  	mdk_rdev_t *rdev, *rdev2;
  
  	rcu_read_lock();
  	rdev_for_each_rcu(rdev, mddev1)
  		rdev_for_each_rcu(rdev2, mddev2)
  			if (rdev->bdev->bd_contains ==
  			    rdev2->bdev->bd_contains) {
  				rcu_read_unlock();
  				return 1;
  			}
  	rcu_read_unlock();
  	return 0;
  }
  
  static LIST_HEAD(pending_raid_disks);
  
  /*
   * Try to register data integrity profile for an mddev
   *
   * This is called when an array is started and after a disk has been kicked
   * from the array. It only succeeds if all working and active component devices
   * are integrity capable with matching profiles.
   */
  int md_integrity_register(mddev_t *mddev)
  {
  	mdk_rdev_t *rdev, *reference = NULL;
  
  	if (list_empty(&mddev->disks))
  		return 0; /* nothing to do */
  	if (!mddev->gendisk || blk_get_integrity(mddev->gendisk))
  		return 0; /* shouldn't register, or already is */
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		/* skip spares and non-functional disks */
  		if (test_bit(Faulty, &rdev->flags))
  			continue;
  		if (rdev->raid_disk < 0)
  			continue;
  		if (!reference) {
  			/* Use the first rdev as the reference */
  			reference = rdev;
  			continue;
  		}
  		/* does this rdev's profile match the reference profile? */
  		if (blk_integrity_compare(reference->bdev->bd_disk,
  				rdev->bdev->bd_disk) < 0)
  			return -EINVAL;
  	}
  	if (!reference || !bdev_get_integrity(reference->bdev))
  		return 0;
  	/*
  	 * All component devices are integrity capable and have matching
  	 * profiles, register the common profile for the md device.
  	 */
  	if (blk_integrity_register(mddev->gendisk,
  			bdev_get_integrity(reference->bdev)) != 0) {
  		printk(KERN_ERR "md: failed to register integrity for %s\n",
  			mdname(mddev));
  		return -EINVAL;
  	}
  	printk(KERN_NOTICE "md: data integrity enabled on %s\n", mdname(mddev));
  	if (bioset_integrity_create(mddev->bio_set, BIO_POOL_SIZE)) {
  		printk(KERN_ERR "md: failed to create integrity pool for %s\n",
  		       mdname(mddev));
  		return -EINVAL;
  	}
  	return 0;
  }
  EXPORT_SYMBOL(md_integrity_register);
  
  /* Disable data integrity if non-capable/non-matching disk is being added */
  void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
  {
  	struct blk_integrity *bi_rdev = bdev_get_integrity(rdev->bdev);
  	struct blk_integrity *bi_mddev = blk_get_integrity(mddev->gendisk);
  
  	if (!bi_mddev) /* nothing to do */
  		return;
  	if (rdev->raid_disk < 0) /* skip spares */
  		return;
  	if (bi_rdev && blk_integrity_compare(mddev->gendisk,
  					     rdev->bdev->bd_disk) >= 0)
  		return;
  	printk(KERN_NOTICE "disabling data integrity on %s\n", mdname(mddev));
  	blk_integrity_unregister(mddev->gendisk);
  }
  EXPORT_SYMBOL(md_integrity_add_rdev);
  
  static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
  {
  	char b[BDEVNAME_SIZE];
  	struct kobject *ko;
  	char *s;
  	int err;
  
  	if (rdev->mddev) {
  		MD_BUG();
  		return -EINVAL;
  	}
  
  	/* prevent duplicates */
  	if (find_rdev(mddev, rdev->bdev->bd_dev))
  		return -EEXIST;
  
  	/* make sure rdev->sectors exceeds mddev->dev_sectors */
  	if (rdev->sectors && (mddev->dev_sectors == 0 ||
  			rdev->sectors < mddev->dev_sectors)) {
  		if (mddev->pers) {
  			/* Cannot change size, so fail
  			 * If mddev->level <= 0, then we don't care
  			 * about aligning sizes (e.g. linear)
  			 */
  			if (mddev->level > 0)
  				return -ENOSPC;
  		} else
  			mddev->dev_sectors = rdev->sectors;
  	}
  
  	/* Verify rdev->desc_nr is unique.
  	 * If it is -1, assign a free number, else
  	 * check number is not in use
  	 */
  	if (rdev->desc_nr < 0) {
  		int choice = 0;
  		if (mddev->pers) choice = mddev->raid_disks;
  		while (find_rdev_nr(mddev, choice))
  			choice++;
  		rdev->desc_nr = choice;
  	} else {
  		if (find_rdev_nr(mddev, rdev->desc_nr))
  			return -EBUSY;
  	}
  	if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
  		printk(KERN_WARNING "md: %s: array is limited to %d devices\n",
  		       mdname(mddev), mddev->max_disks);
  		return -EBUSY;
  	}
  	bdevname(rdev->bdev,b);
  	while ( (s=strchr(b, '/')) != NULL)
  		*s = '!';
  
  	rdev->mddev = mddev;
  	printk(KERN_INFO "md: bind<%s>\n", b);
  
  	if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
  		goto fail;
  
  	ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
  	if (sysfs_create_link(&rdev->kobj, ko, "block"))
  		/* failure here is OK */;
  	rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
  
  	list_add_rcu(&rdev->same_set, &mddev->disks);
  	bd_link_disk_holder(rdev->bdev, mddev->gendisk);
  
  	/* May as well allow recovery to be retried once */
  	mddev->recovery_disabled = 0;
  
  	return 0;
  
   fail:
  	printk(KERN_WARNING "md: failed to register dev-%s for %s\n",
  	       b, mdname(mddev));
  	return err;
  }
  
  static void md_delayed_delete(struct work_struct *ws)
  {
  	mdk_rdev_t *rdev = container_of(ws, mdk_rdev_t, del_work);
  	kobject_del(&rdev->kobj);
  	kobject_put(&rdev->kobj);
  }
  
  static void unbind_rdev_from_array(mdk_rdev_t * rdev)
  {
  	char b[BDEVNAME_SIZE];
  	if (!rdev->mddev) {
  		MD_BUG();
  		return;
  	}
  	bd_unlink_disk_holder(rdev->bdev, rdev->mddev->gendisk);
  	list_del_rcu(&rdev->same_set);
  	printk(KERN_INFO "md: unbind<%s>\n", bdevname(rdev->bdev,b));
  	rdev->mddev = NULL;
  	sysfs_remove_link(&rdev->kobj, "block");
  	sysfs_put(rdev->sysfs_state);
  	rdev->sysfs_state = NULL;
  	/* We need to delay this, otherwise we can deadlock when
  	 * writing to 'remove' to "dev/state".  We also need
  	 * to delay it due to rcu usage.
  	 */
  	synchronize_rcu();
  	INIT_WORK(&rdev->del_work, md_delayed_delete);
  	kobject_get(&rdev->kobj);
  	queue_work(md_misc_wq, &rdev->del_work);
  }
  
  /*
   * prevent the device from being mounted, repartitioned or
   * otherwise reused by a RAID array (or any other kernel
   * subsystem), by bd_claiming the device.
   */
  static int lock_rdev(mdk_rdev_t *rdev, dev_t dev, int shared)
  {
  	int err = 0;
  	struct block_device *bdev;
  	char b[BDEVNAME_SIZE];
  
  	bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
  				 shared ? (mdk_rdev_t *)lock_rdev : rdev);
  	if (IS_ERR(bdev)) {
  		printk(KERN_ERR "md: could not open %s.\n",
  			__bdevname(dev, b));
  		return PTR_ERR(bdev);
  	}
  	rdev->bdev = bdev;
  	return err;
  }
  
  static void unlock_rdev(mdk_rdev_t *rdev)
  {
  	struct block_device *bdev = rdev->bdev;
  	rdev->bdev = NULL;
  	if (!bdev)
  		MD_BUG();
  	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
  }
  
  void md_autodetect_dev(dev_t dev);
  
  static void export_rdev(mdk_rdev_t * rdev)
  {
  	char b[BDEVNAME_SIZE];
  	printk(KERN_INFO "md: export_rdev(%s)\n",
  		bdevname(rdev->bdev,b));
  	if (rdev->mddev)
  		MD_BUG();
  	free_disk_sb(rdev);
  #ifndef MODULE
  	if (test_bit(AutoDetected, &rdev->flags))
  		md_autodetect_dev(rdev->bdev->bd_dev);
  #endif
  	unlock_rdev(rdev);
  	kobject_put(&rdev->kobj);
  }
  
  static void kick_rdev_from_array(mdk_rdev_t * rdev)
  {
  	unbind_rdev_from_array(rdev);
  	export_rdev(rdev);
  }
  
  static void export_array(mddev_t *mddev)
  {
  	mdk_rdev_t *rdev, *tmp;
  
  	rdev_for_each(rdev, tmp, mddev) {
  		if (!rdev->mddev) {
  			MD_BUG();
  			continue;
  		}
  		kick_rdev_from_array(rdev);
  	}
  	if (!list_empty(&mddev->disks))
  		MD_BUG();
  	mddev->raid_disks = 0;
  	mddev->major_version = 0;
  }
  
  static void print_desc(mdp_disk_t *desc)
  {
  	printk(" DISK<N:%d,(%d,%d),R:%d,S:%d>\n", desc->number,
  		desc->major,desc->minor,desc->raid_disk,desc->state);
  }
  
  static void print_sb_90(mdp_super_t *sb)
  {
  	int i;
  
  	printk(KERN_INFO
  		"md:  SB: (V:%d.%d.%d) ID:<%08x.%08x.%08x.%08x> CT:%08x\n",
  		sb->major_version, sb->minor_version, sb->patch_version,
  		sb->set_uuid0, sb->set_uuid1, sb->set_uuid2, sb->set_uuid3,
  		sb->ctime);
  	printk(KERN_INFO "md:     L%d S%08d ND:%d RD:%d md%d LO:%d CS:%d\n",
  		sb->level, sb->size, sb->nr_disks, sb->raid_disks,
  		sb->md_minor, sb->layout, sb->chunk_size);
  	printk(KERN_INFO "md:     UT:%08x ST:%d AD:%d WD:%d"
  		" FD:%d SD:%d CSUM:%08x E:%08lx\n",
  		sb->utime, sb->state, sb->active_disks, sb->working_disks,
  		sb->failed_disks, sb->spare_disks,
  		sb->sb_csum, (unsigned long)sb->events_lo);
  
  	printk(KERN_INFO);
  	for (i = 0; i < MD_SB_DISKS; i++) {
  		mdp_disk_t *desc;
  
  		desc = sb->disks + i;
  		if (desc->number || desc->major || desc->minor ||
  		    desc->raid_disk || (desc->state && (desc->state != 4))) {
  			printk("     D %2d: ", i);
  			print_desc(desc);
  		}
  	}
  	printk(KERN_INFO "md:     THIS: ");
  	print_desc(&sb->this_disk);
  }
  
  static void print_sb_1(struct mdp_superblock_1 *sb)
  {
  	__u8 *uuid;
  
  	uuid = sb->set_uuid;
  	printk(KERN_INFO
  	       "md:  SB: (V:%u) (F:0x%08x) Array-ID:<%pU>\n"
  	       "md:    Name: \"%s\" CT:%llu\n",
  		le32_to_cpu(sb->major_version),
  		le32_to_cpu(sb->feature_map),
  		uuid,
  		sb->set_name,
  		(unsigned long long)le64_to_cpu(sb->ctime)
  		       & MD_SUPERBLOCK_1_TIME_SEC_MASK);
  
  	uuid = sb->device_uuid;
  	printk(KERN_INFO
  	       "md:       L%u SZ%llu RD:%u LO:%u CS:%u DO:%llu DS:%llu SO:%llu"
  			" RO:%llu\n"
  	       "md:     Dev:%08x UUID: %pU\n"
  	       "md:       (F:0x%08x) UT:%llu Events:%llu ResyncOffset:%llu CSUM:0x%08x\n"
  	       "md:         (MaxDev:%u) \n",
  		le32_to_cpu(sb->level),
  		(unsigned long long)le64_to_cpu(sb->size),
  		le32_to_cpu(sb->raid_disks),
  		le32_to_cpu(sb->layout),
  		le32_to_cpu(sb->chunksize),
  		(unsigned long long)le64_to_cpu(sb->data_offset),
  		(unsigned long long)le64_to_cpu(sb->data_size),
  		(unsigned long long)le64_to_cpu(sb->super_offset),
  		(unsigned long long)le64_to_cpu(sb->recovery_offset),
  		le32_to_cpu(sb->dev_number),
  		uuid,
  		sb->devflags,
  		(unsigned long long)le64_to_cpu(sb->utime) & MD_SUPERBLOCK_1_TIME_SEC_MASK,
  		(unsigned long long)le64_to_cpu(sb->events),
  		(unsigned long long)le64_to_cpu(sb->resync_offset),
  		le32_to_cpu(sb->sb_csum),
  		le32_to_cpu(sb->max_dev)
  		);
  }
  
  static void print_rdev(mdk_rdev_t *rdev, int major_version)
  {
  	char b[BDEVNAME_SIZE];
  	printk(KERN_INFO "md: rdev %s, Sect:%08llu F:%d S:%d DN:%u\n",
  		bdevname(rdev->bdev, b), (unsigned long long)rdev->sectors,
  	        test_bit(Faulty, &rdev->flags), test_bit(In_sync, &rdev->flags),
  	        rdev->desc_nr);
  	if (rdev->sb_loaded) {
  		printk(KERN_INFO "md: rdev superblock (MJ:%d):\n", major_version);
  		switch (major_version) {
  		case 0:
  			print_sb_90((mdp_super_t*)page_address(rdev->sb_page));
  			break;
  		case 1:
  			print_sb_1((struct mdp_superblock_1 *)page_address(rdev->sb_page));
  			break;
  		}
  	} else
  		printk(KERN_INFO "md: no rdev superblock!\n");
  }
  
  static void md_print_devices(void)
  {
  	struct list_head *tmp;
  	mdk_rdev_t *rdev;
  	mddev_t *mddev;
  	char b[BDEVNAME_SIZE];
  
  	printk("\n");
  	printk("md:	**********************************\n");
  	printk("md:	* <COMPLETE RAID STATE PRINTOUT> *\n");
  	printk("md:	**********************************\n");
  	for_each_mddev(mddev, tmp) {
  
  		if (mddev->bitmap)
  			bitmap_print_sb(mddev->bitmap);
  		else
  			printk("%s: ", mdname(mddev));
  		list_for_each_entry(rdev, &mddev->disks, same_set)
  			printk("<%s>", bdevname(rdev->bdev,b));
  		printk("\n");
  
  		list_for_each_entry(rdev, &mddev->disks, same_set)
  			print_rdev(rdev, mddev->major_version);
  	}
  	printk("md:	**********************************\n");
  	printk("\n");
  }
  
  static void sync_sbs(mddev_t * mddev, int nospares)
  {
  	/* Update each superblock (in-memory image), but
  	 * if we are allowed to, skip spares which already
  	 * have the right event counter, or have one earlier
  	 * (which would mean they aren't being marked as dirty
  	 * with the rest of the array)
  	 */
  	mdk_rdev_t *rdev;
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		if (rdev->sb_events == mddev->events ||
  		    (nospares &&
  		     rdev->raid_disk < 0 &&
  		     rdev->sb_events+1 == mddev->events)) {
  			/* Don't update this superblock */
  			rdev->sb_loaded = 2;
  		} else {
  			sync_super(mddev, rdev);
  			rdev->sb_loaded = 1;
  		}
  	}
  }
  
  static void md_update_sb(mddev_t * mddev, int force_change)
  {
  	mdk_rdev_t *rdev;
  	int sync_req;
  	int nospares = 0;
  
  repeat:
  	/* First make sure individual recovery_offsets are correct */
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		if (rdev->raid_disk >= 0 &&
  		    mddev->delta_disks >= 0 &&
  		    !test_bit(In_sync, &rdev->flags) &&
  		    mddev->curr_resync_completed > rdev->recovery_offset)
  				rdev->recovery_offset = mddev->curr_resync_completed;
  
  	}
  	if (!mddev->persistent) {
  		clear_bit(MD_CHANGE_CLEAN, &mddev->flags);
  		clear_bit(MD_CHANGE_DEVS, &mddev->flags);
  		if (!mddev->external)
  			clear_bit(MD_CHANGE_PENDING, &mddev->flags);
  		wake_up(&mddev->sb_wait);
  		return;
  	}
  
  	spin_lock_irq(&mddev->write_lock);
  
  	mddev->utime = get_seconds();
  
  	if (test_and_clear_bit(MD_CHANGE_DEVS, &mddev->flags))
  		force_change = 1;
  	if (test_and_clear_bit(MD_CHANGE_CLEAN, &mddev->flags))
  		/* just a clean<-> dirty transition, possibly leave spares alone,
  		 * though if events isn't the right even/odd, we will have to do
  		 * spares after all
  		 */
  		nospares = 1;
  	if (force_change)
  		nospares = 0;
  	if (mddev->degraded)
  		/* If the array is degraded, then skipping spares is both
  		 * dangerous and fairly pointless.
  		 * Dangerous because a device that was removed from the array
  		 * might have a event_count that still looks up-to-date,
  		 * so it can be re-added without a resync.
  		 * Pointless because if there are any spares to skip,
  		 * then a recovery will happen and soon that array won't
  		 * be degraded any more and the spare can go back to sleep then.
  		 */
  		nospares = 0;
  
  	sync_req = mddev->in_sync;
  
  	/* If this is just a dirty<->clean transition, and the array is clean
  	 * and 'events' is odd, we can roll back to the previous clean state */
  	if (nospares
  	    && (mddev->in_sync && mddev->recovery_cp == MaxSector)
  	    && mddev->can_decrease_events
  	    && mddev->events != 1) {
  		mddev->events--;
  		mddev->can_decrease_events = 0;
  	} else {
  		/* otherwise we have to go forward and ... */
  		mddev->events ++;
  		mddev->can_decrease_events = nospares;
  	}
  
  	if (!mddev->events) {
  		/*
  		 * oops, this 64-bit counter should never wrap.
  		 * Either we are in around ~1 trillion A.C., assuming
  		 * 1 reboot per second, or we have a bug:
  		 */
  		MD_BUG();
  		mddev->events --;
  	}
  	sync_sbs(mddev, nospares);
  	spin_unlock_irq(&mddev->write_lock);
  
  	dprintk(KERN_INFO
  		"md: updating %s RAID superblock on device (in sync %d)\n",
  		mdname(mddev),mddev->in_sync);
  
  	bitmap_update_sb(mddev->bitmap);
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		char b[BDEVNAME_SIZE];
  		dprintk(KERN_INFO "md: ");
  		if (rdev->sb_loaded != 1)
  			continue; /* no noise on spare devices */
  		if (test_bit(Faulty, &rdev->flags))
  			dprintk("(skipping faulty ");
  
  		dprintk("%s ", bdevname(rdev->bdev,b));
  		if (!test_bit(Faulty, &rdev->flags)) {
  			md_super_write(mddev,rdev,
  				       rdev->sb_start, rdev->sb_size,
  				       rdev->sb_page);
  			dprintk(KERN_INFO "(write) %s's sb offset: %llu\n",
  				bdevname(rdev->bdev,b),
  				(unsigned long long)rdev->sb_start);
  			rdev->sb_events = mddev->events;
  
  		} else
  			dprintk(")\n");
  		if (mddev->level == LEVEL_MULTIPATH)
  			/* only need to write one superblock... */
  			break;
  	}
  	md_super_wait(mddev);
  	/* if there was a failure, MD_CHANGE_DEVS was set, and we re-write super */
  
  	spin_lock_irq(&mddev->write_lock);
  	if (mddev->in_sync != sync_req ||
  	    test_bit(MD_CHANGE_DEVS, &mddev->flags)) {
  		/* have to write it out again */
  		spin_unlock_irq(&mddev->write_lock);
  		goto repeat;
  	}
  	clear_bit(MD_CHANGE_PENDING, &mddev->flags);
  	spin_unlock_irq(&mddev->write_lock);
  	wake_up(&mddev->sb_wait);
  	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
  		sysfs_notify(&mddev->kobj, NULL, "sync_completed");
  
  }
  
  /* words written to sysfs files may, or may not, be \n terminated.
   * We want to accept with case. For this we use cmd_match.
   */
  static int cmd_match(const char *cmd, const char *str)
  {
  	/* See if cmd, written into a sysfs file, matches
  	 * str.  They must either be the same, or cmd can
  	 * have a trailing newline
  	 */
  	while (*cmd && *str && *cmd == *str) {
  		cmd++;
  		str++;
  	}
  	if (*cmd == '\n')
  		cmd++;
  	if (*str || *cmd)
  		return 0;
  	return 1;
  }
  
  struct rdev_sysfs_entry {
  	struct attribute attr;
  	ssize_t (*show)(mdk_rdev_t *, char *);
  	ssize_t (*store)(mdk_rdev_t *, const char *, size_t);
  };
  
  static ssize_t
  state_show(mdk_rdev_t *rdev, char *page)
  {
  	char *sep = "";
  	size_t len = 0;
  
  	if (test_bit(Faulty, &rdev->flags)) {
  		len+= sprintf(page+len, "%sfaulty",sep);
  		sep = ",";
  	}
  	if (test_bit(In_sync, &rdev->flags)) {
  		len += sprintf(page+len, "%sin_sync",sep);
  		sep = ",";
  	}
  	if (test_bit(WriteMostly, &rdev->flags)) {
  		len += sprintf(page+len, "%swrite_mostly",sep);
  		sep = ",";
  	}
  	if (test_bit(Blocked, &rdev->flags)) {
  		len += sprintf(page+len, "%sblocked", sep);
  		sep = ",";
  	}
  	if (!test_bit(Faulty, &rdev->flags) &&
  	    !test_bit(In_sync, &rdev->flags)) {
  		len += sprintf(page+len, "%sspare", sep);
  		sep = ",";
  	}
  	return len+sprintf(page+len, "\n");
  }
  
  static ssize_t
  state_store(mdk_rdev_t *rdev, const char *buf, size_t len)
  {
  	/* can write
  	 *  faulty  - simulates and error
  	 *  remove  - disconnects the device
  	 *  writemostly - sets write_mostly
  	 *  -writemostly - clears write_mostly
  	 *  blocked - sets the Blocked flag
  	 *  -blocked - clears the Blocked flag
  	 *  insync - sets Insync providing device isn't active
  	 */
  	int err = -EINVAL;
  	if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
  		md_error(rdev->mddev, rdev);
  		err = 0;
  	} else if (cmd_match(buf, "remove")) {
  		if (rdev->raid_disk >= 0)
  			err = -EBUSY;
  		else {
  			mddev_t *mddev = rdev->mddev;
  			kick_rdev_from_array(rdev);
  			if (mddev->pers)
  				md_update_sb(mddev, 1);
  			md_new_event(mddev);
  			err = 0;
  		}
  	} else if (cmd_match(buf, "writemostly")) {
  		set_bit(WriteMostly, &rdev->flags);
  		err = 0;
  	} else if (cmd_match(buf, "-writemostly")) {
  		clear_bit(WriteMostly, &rdev->flags);
  		err = 0;
  	} else if (cmd_match(buf, "blocked")) {
  		set_bit(Blocked, &rdev->flags);
  		err = 0;
  	} else if (cmd_match(buf, "-blocked")) {
  		clear_bit(Blocked, &rdev->flags);
  		wake_up(&rdev->blocked_wait);
  		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
  		md_wakeup_thread(rdev->mddev->thread);
  
  		err = 0;
  	} else if (cmd_match(buf, "insync") && rdev->raid_disk == -1) {
  		set_bit(In_sync, &rdev->flags);
  		err = 0;
  	}
  	if (!err)
  		sysfs_notify_dirent_safe(rdev->sysfs_state);
  	return err ? err : len;
  }
  static struct rdev_sysfs_entry rdev_state =
  __ATTR(state, S_IRUGO|S_IWUSR, state_show, state_store);
  
  static ssize_t
  errors_show(mdk_rdev_t *rdev, char *page)
  {
  	return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
  }
  
  static ssize_t
  errors_store(mdk_rdev_t *rdev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long n = simple_strtoul(buf, &e, 10);
  	if (*buf && (*e == 0 || *e == '\n')) {
  		atomic_set(&rdev->corrected_errors, n);
  		return len;
  	}
  	return -EINVAL;
  }
  static struct rdev_sysfs_entry rdev_errors =
  __ATTR(errors, S_IRUGO|S_IWUSR, errors_show, errors_store);
  
  static ssize_t
  slot_show(mdk_rdev_t *rdev, char *page)
  {
  	if (rdev->raid_disk < 0)
  		return sprintf(page, "none\n");
  	else
  		return sprintf(page, "%d\n", rdev->raid_disk);
  }
  
  static ssize_t
  slot_store(mdk_rdev_t *rdev, const char *buf, size_t len)
  {
  	char *e;
  	int err;
  	char nm[20];
  	int slot = simple_strtoul(buf, &e, 10);
  	if (strncmp(buf, "none", 4)==0)
  		slot = -1;
  	else if (e==buf || (*e && *e!= '\n'))
  		return -EINVAL;
  	if (rdev->mddev->pers && slot == -1) {
  		/* Setting 'slot' on an active array requires also
  		 * updating the 'rd%d' link, and communicating
  		 * with the personality with ->hot_*_disk.
  		 * For now we only support removing
  		 * failed/spare devices.  This normally happens automatically,
  		 * but not when the metadata is externally managed.
  		 */
  		if (rdev->raid_disk == -1)
  			return -EEXIST;
  		/* personality does all needed checks */
  		if (rdev->mddev->pers->hot_remove_disk == NULL)
  			return -EINVAL;
  		err = rdev->mddev->pers->
  			hot_remove_disk(rdev->mddev, rdev->raid_disk);
  		if (err)
  			return err;
  		sprintf(nm, "rd%d", rdev->raid_disk);
  		sysfs_remove_link(&rdev->mddev->kobj, nm);
  		rdev->raid_disk = -1;
  		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
  		md_wakeup_thread(rdev->mddev->thread);
  	} else if (rdev->mddev->pers) {
  		mdk_rdev_t *rdev2;
  		/* Activating a spare .. or possibly reactivating
  		 * if we ever get bitmaps working here.
  		 */
  
  		if (rdev->raid_disk != -1)
  			return -EBUSY;
  
  		if (test_bit(MD_RECOVERY_RUNNING, &rdev->mddev->recovery))
  			return -EBUSY;
  
  		if (rdev->mddev->pers->hot_add_disk == NULL)
  			return -EINVAL;
  
  		list_for_each_entry(rdev2, &rdev->mddev->disks, same_set)
  			if (rdev2->raid_disk == slot)
  				return -EEXIST;
  
  		if (slot >= rdev->mddev->raid_disks &&
  		    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
  			return -ENOSPC;
  
  		rdev->raid_disk = slot;
  		if (test_bit(In_sync, &rdev->flags))
  			rdev->saved_raid_disk = slot;
  		else
  			rdev->saved_raid_disk = -1;
  		err = rdev->mddev->pers->
  			hot_add_disk(rdev->mddev, rdev);
  		if (err) {
  			rdev->raid_disk = -1;
  			return err;
  		} else
  			sysfs_notify_dirent_safe(rdev->sysfs_state);
  		sprintf(nm, "rd%d", rdev->raid_disk);
  		if (sysfs_create_link(&rdev->mddev->kobj, &rdev->kobj, nm))
  			/* failure here is OK */;
  		/* don't wakeup anyone, leave that to userspace. */
  	} else {
  		if (slot >= rdev->mddev->raid_disks &&
  		    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
  			return -ENOSPC;
  		rdev->raid_disk = slot;
  		/* assume it is working */
  		clear_bit(Faulty, &rdev->flags);
  		clear_bit(WriteMostly, &rdev->flags);
  		set_bit(In_sync, &rdev->flags);
  		sysfs_notify_dirent_safe(rdev->sysfs_state);
  	}
  	return len;
  }
  
  static struct rdev_sysfs_entry rdev_slot =
  __ATTR(slot, S_IRUGO|S_IWUSR, slot_show, slot_store);
  
  static ssize_t
  offset_show(mdk_rdev_t *rdev, char *page)
  {
  	return sprintf(page, "%llu\n", (unsigned long long)rdev->data_offset);
  }
  
  static ssize_t
  offset_store(mdk_rdev_t *rdev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long long offset = simple_strtoull(buf, &e, 10);
  	if (e==buf || (*e && *e != '\n'))
  		return -EINVAL;
  	if (rdev->mddev->pers && rdev->raid_disk >= 0)
  		return -EBUSY;
  	if (rdev->sectors && rdev->mddev->external)
  		/* Must set offset before size, so overlap checks
  		 * can be sane */
  		return -EBUSY;
  	rdev->data_offset = offset;
  	return len;
  }
  
  static struct rdev_sysfs_entry rdev_offset =
  __ATTR(offset, S_IRUGO|S_IWUSR, offset_show, offset_store);
  
  static ssize_t
  rdev_size_show(mdk_rdev_t *rdev, char *page)
  {
  	return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);
  }
  
  static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
  {
  	/* check if two start/length pairs overlap */
  	if (s1+l1 <= s2)
  		return 0;
  	if (s2+l2 <= s1)
  		return 0;
  	return 1;
  }
  
  static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
  {
  	unsigned long long blocks;
  	sector_t new;
  
  	if (strict_strtoull(buf, 10, &blocks) < 0)
  		return -EINVAL;
  
  	if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
  		return -EINVAL; /* sector conversion overflow */
  
  	new = blocks * 2;
  	if (new != blocks * 2)
  		return -EINVAL; /* unsigned long long to sector_t overflow */
  
  	*sectors = new;
  	return 0;
  }
  
  static ssize_t
  rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
  {
  	mddev_t *my_mddev = rdev->mddev;
  	sector_t oldsectors = rdev->sectors;
  	sector_t sectors;
  
  	if (strict_blocks_to_sectors(buf, &sectors) < 0)
  		return -EINVAL;
  	if (my_mddev->pers && rdev->raid_disk >= 0) {
  		if (my_mddev->persistent) {
  			sectors = super_types[my_mddev->major_version].
  				rdev_size_change(rdev, sectors);
  			if (!sectors)
  				return -EBUSY;
  		} else if (!sectors)
  			sectors = (i_size_read(rdev->bdev->bd_inode) >> 9) -
  				rdev->data_offset;
  	}
  	if (sectors < my_mddev->dev_sectors)
  		return -EINVAL; /* component must fit device */
  
  	rdev->sectors = sectors;
  	if (sectors > oldsectors && my_mddev->external) {
  		/* need to check that all other rdevs with the same ->bdev
  		 * do not overlap.  We need to unlock the mddev to avoid
  		 * a deadlock.  We have already changed rdev->sectors, and if
  		 * we have to change it back, we will have the lock again.
  		 */
  		mddev_t *mddev;
  		int overlap = 0;
  		struct list_head *tmp;
  
  		mddev_unlock(my_mddev);
  		for_each_mddev(mddev, tmp) {
  			mdk_rdev_t *rdev2;
  
  			mddev_lock(mddev);
  			list_for_each_entry(rdev2, &mddev->disks, same_set)
  				if (rdev->bdev == rdev2->bdev &&
  				    rdev != rdev2 &&
  				    overlaps(rdev->data_offset, rdev->sectors,
  					     rdev2->data_offset,
  					     rdev2->sectors)) {
  					overlap = 1;
  					break;
  				}
  			mddev_unlock(mddev);
  			if (overlap) {
  				mddev_put(mddev);
  				break;
  			}
  		}
  		mddev_lock(my_mddev);
  		if (overlap) {
  			/* Someone else could have slipped in a size
  			 * change here, but doing so is just silly.
  			 * We put oldsectors back because we *know* it is
  			 * safe, and trust userspace not to race with
  			 * itself
  			 */
  			rdev->sectors = oldsectors;
  			return -EBUSY;
  		}
  	}
  	return len;
  }
  
  static struct rdev_sysfs_entry rdev_size =
  __ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);
  
  static ssize_t recovery_start_show(mdk_rdev_t *rdev, char *page)
  {
  	unsigned long long recovery_start = rdev->recovery_offset;
  
  	if (test_bit(In_sync, &rdev->flags) ||
  	    recovery_start == MaxSector)
  		return sprintf(page, "none\n");
  
  	return sprintf(page, "%llu\n", recovery_start);
  }
  
  static ssize_t recovery_start_store(mdk_rdev_t *rdev, const char *buf, size_t len)
  {
  	unsigned long long recovery_start;
  
  	if (cmd_match(buf, "none"))
  		recovery_start = MaxSector;
  	else if (strict_strtoull(buf, 10, &recovery_start))
  		return -EINVAL;
  
  	if (rdev->mddev->pers &&
  	    rdev->raid_disk >= 0)
  		return -EBUSY;
  
  	rdev->recovery_offset = recovery_start;
  	if (recovery_start == MaxSector)
  		set_bit(In_sync, &rdev->flags);
  	else
  		clear_bit(In_sync, &rdev->flags);
  	return len;
  }
  
  static struct rdev_sysfs_entry rdev_recovery_start =
  __ATTR(recovery_start, S_IRUGO|S_IWUSR, recovery_start_show, recovery_start_store);
  
  static struct attribute *rdev_default_attrs[] = {
  	&rdev_state.attr,
  	&rdev_errors.attr,
  	&rdev_slot.attr,
  	&rdev_offset.attr,
  	&rdev_size.attr,
  	&rdev_recovery_start.attr,
  	NULL,
  };
  static ssize_t
  rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
  {
  	struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
  	mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);
  	mddev_t *mddev = rdev->mddev;
  	ssize_t rv;
  
  	if (!entry->show)
  		return -EIO;
  
  	rv = mddev ? mddev_lock(mddev) : -EBUSY;
  	if (!rv) {
  		if (rdev->mddev == NULL)
  			rv = -EBUSY;
  		else
  			rv = entry->show(rdev, page);
  		mddev_unlock(mddev);
  	}
  	return rv;
  }
  
  static ssize_t
  rdev_attr_store(struct kobject *kobj, struct attribute *attr,
  	      const char *page, size_t length)
  {
  	struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
  	mdk_rdev_t *rdev = container_of(kobj, mdk_rdev_t, kobj);
  	ssize_t rv;
  	mddev_t *mddev = rdev->mddev;
  
  	if (!entry->store)
  		return -EIO;
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;
  	rv = mddev ? mddev_lock(mddev): -EBUSY;
  	if (!rv) {
  		if (rdev->mddev == NULL)
  			rv = -EBUSY;
  		else
  			rv = entry->store(rdev, page, length);
  		mddev_unlock(mddev);
  	}
  	return rv;
  }
  
  static void rdev_free(struct kobject *ko)
  {
  	mdk_rdev_t *rdev = container_of(ko, mdk_rdev_t, kobj);
  	kfree(rdev);
  }
  static const struct sysfs_ops rdev_sysfs_ops = {
  	.show		= rdev_attr_show,
  	.store		= rdev_attr_store,
  };
  static struct kobj_type rdev_ktype = {
  	.release	= rdev_free,
  	.sysfs_ops	= &rdev_sysfs_ops,
  	.default_attrs	= rdev_default_attrs,
  };
  
  void md_rdev_init(mdk_rdev_t *rdev)
  {
  	rdev->desc_nr = -1;
  	rdev->saved_raid_disk = -1;
  	rdev->raid_disk = -1;
  	rdev->flags = 0;
  	rdev->data_offset = 0;
  	rdev->sb_events = 0;
  	rdev->last_read_error.tv_sec  = 0;
  	rdev->last_read_error.tv_nsec = 0;
  	atomic_set(&rdev->nr_pending, 0);
  	atomic_set(&rdev->read_errors, 0);
  	atomic_set(&rdev->corrected_errors, 0);
  
  	INIT_LIST_HEAD(&rdev->same_set);
  	init_waitqueue_head(&rdev->blocked_wait);
  }
  EXPORT_SYMBOL_GPL(md_rdev_init);
  /*
   * Import a device. If 'super_format' >= 0, then sanity check the superblock
   *
   * mark the device faulty if:
   *
   *   - the device is nonexistent (zero size)
   *   - the device has no valid superblock
   *
   * a faulty rdev _never_ has rdev->sb set.
   */
  static mdk_rdev_t *md_import_device(dev_t newdev, int super_format, int super_minor)
  {
  	char b[BDEVNAME_SIZE];
  	int err;
  	mdk_rdev_t *rdev;
  	sector_t size;
  
  	rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
  	if (!rdev) {
  		printk(KERN_ERR "md: could not alloc mem for new device!\n");
  		return ERR_PTR(-ENOMEM);
  	}
  
  	md_rdev_init(rdev);
  	if ((err = alloc_disk_sb(rdev)))
  		goto abort_free;
  
  	err = lock_rdev(rdev, newdev, super_format == -2);
  	if (err)
  		goto abort_free;
  
  	kobject_init(&rdev->kobj, &rdev_ktype);
  
  	size = i_size_read(rdev->bdev->bd_inode) >> BLOCK_SIZE_BITS;
  	if (!size) {
  		printk(KERN_WARNING
  			"md: %s has zero or unknown size, marking faulty!\n",
  			bdevname(rdev->bdev,b));
  		err = -EINVAL;
  		goto abort_free;
  	}
  
  	if (super_format >= 0) {
  		err = super_types[super_format].
  			load_super(rdev, NULL, super_minor);
  		if (err == -EINVAL) {
  			printk(KERN_WARNING
  				"md: %s does not have a valid v%d.%d "
  			       "superblock, not importing!\n",
  				bdevname(rdev->bdev,b),
  			       super_format, super_minor);
  			goto abort_free;
  		}
  		if (err < 0) {
  			printk(KERN_WARNING
  				"md: could not read %s's sb, not importing!\n",
  				bdevname(rdev->bdev,b));
  			goto abort_free;
  		}
  	}
  
  	return rdev;
  
  abort_free:
  	if (rdev->sb_page) {
  		if (rdev->bdev)
  			unlock_rdev(rdev);
  		free_disk_sb(rdev);
  	}
  	kfree(rdev);
  	return ERR_PTR(err);
  }
  
  /*
   * Check a full RAID array for plausibility
   */
  
  static void analyze_sbs(mddev_t * mddev)
  {
  	int i;
  	mdk_rdev_t *rdev, *freshest, *tmp;
  	char b[BDEVNAME_SIZE];
  
  	freshest = NULL;
  	rdev_for_each(rdev, tmp, mddev)
  		switch (super_types[mddev->major_version].
  			load_super(rdev, freshest, mddev->minor_version)) {
  		case 1:
  			freshest = rdev;
  			break;
  		case 0:
  			break;
  		default:
  			printk( KERN_ERR \
  				"md: fatal superblock inconsistency in %s"
  				" -- removing from array\n",
  				bdevname(rdev->bdev,b));
  			kick_rdev_from_array(rdev);
  		}
  
  	super_types[mddev->major_version].
  		validate_super(mddev, freshest);
  
  	i = 0;
  	rdev_for_each(rdev, tmp, mddev) {
  		if (mddev->max_disks &&
  		    (rdev->desc_nr >= mddev->max_disks ||
  		     i > mddev->max_disks)) {
  			printk(KERN_WARNING
  			       "md: %s: %s: only %d devices permitted\n",
  			       mdname(mddev), bdevname(rdev->bdev, b),
  			       mddev->max_disks);
  			kick_rdev_from_array(rdev);
  			continue;
  		}
  		if (rdev != freshest)
  			if (super_types[mddev->major_version].
  			    validate_super(mddev, rdev)) {
  				printk(KERN_WARNING "md: kicking non-fresh %s"
  					" from array!\n",
  					bdevname(rdev->bdev,b));
  				kick_rdev_from_array(rdev);
  				continue;
  			}
  		if (mddev->level == LEVEL_MULTIPATH) {
  			rdev->desc_nr = i++;
  			rdev->raid_disk = rdev->desc_nr;
  			set_bit(In_sync, &rdev->flags);
  		} else if (rdev->raid_disk >= (mddev->raid_disks - min(0, mddev->delta_disks))) {
  			rdev->raid_disk = -1;
  			clear_bit(In_sync, &rdev->flags);
  		}
  	}
  }
  
  /* Read a fixed-point number.
   * Numbers in sysfs attributes should be in "standard" units where
   * possible, so time should be in seconds.
   * However we internally use a a much smaller unit such as
   * milliseconds or jiffies.
   * This function takes a decimal number with a possible fractional
   * component, and produces an integer which is the result of
   * multiplying that number by 10^'scale'.
   * all without any floating-point arithmetic.
   */
  int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
  {
  	unsigned long result = 0;
  	long decimals = -1;
  	while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
  		if (*cp == '.')
  			decimals = 0;
  		else if (decimals < scale) {
  			unsigned int value;
  			value = *cp - '0';
  			result = result * 10 + value;
  			if (decimals >= 0)
  				decimals++;
  		}
  		cp++;
  	}
  	if (*cp == '\n')
  		cp++;
  	if (*cp)
  		return -EINVAL;
  	if (decimals < 0)
  		decimals = 0;
  	while (decimals < scale) {
  		result *= 10;
  		decimals ++;
  	}
  	*res = result;
  	return 0;
  }
  
  static void md_safemode_timeout(unsigned long data);
  
  static ssize_t
  safe_delay_show(mddev_t *mddev, char *page)
  {
  	int msec = (mddev->safemode_delay*1000)/HZ;
  	return sprintf(page, "%d.%03d\n", msec/1000, msec%1000);
  }
  static ssize_t
  safe_delay_store(mddev_t *mddev, const char *cbuf, size_t len)
  {
  	unsigned long msec;
  
  	if (strict_strtoul_scaled(cbuf, &msec, 3) < 0)
  		return -EINVAL;
  	if (msec == 0)
  		mddev->safemode_delay = 0;
  	else {
  		unsigned long old_delay = mddev->safemode_delay;
  		mddev->safemode_delay = (msec*HZ)/1000;
  		if (mddev->safemode_delay == 0)
  			mddev->safemode_delay = 1;
  		if (mddev->safemode_delay < old_delay)
  			md_safemode_timeout((unsigned long)mddev);
  	}
  	return len;
  }
  static struct md_sysfs_entry md_safe_delay =
  __ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store);
  
  static ssize_t
  level_show(mddev_t *mddev, char *page)
  {
  	struct mdk_personality *p = mddev->pers;
  	if (p)
  		return sprintf(page, "%s\n", p->name);
  	else if (mddev->clevel[0])
  		return sprintf(page, "%s\n", mddev->clevel);
  	else if (mddev->level != LEVEL_NONE)
  		return sprintf(page, "%d\n", mddev->level);
  	else
  		return 0;
  }
  
  static ssize_t
  level_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char clevel[16];
  	ssize_t rv = len;
  	struct mdk_personality *pers;
  	long level;
  	void *priv;
  	mdk_rdev_t *rdev;
  
  	if (mddev->pers == NULL) {
  		if (len == 0)
  			return 0;
  		if (len >= sizeof(mddev->clevel))
  			return -ENOSPC;
  		strncpy(mddev->clevel, buf, len);
  		if (mddev->clevel[len-1] == '\n')
  			len--;
  		mddev->clevel[len] = 0;
  		mddev->level = LEVEL_NONE;
  		return rv;
  	}
  
  	/* request to change the personality.  Need to ensure:
  	 *  - array is not engaged in resync/recovery/reshape
  	 *  - old personality can be suspended
  	 *  - new personality will access other array.
  	 */
  
  	if (mddev->sync_thread ||
  	    mddev->reshape_position != MaxSector ||
  	    mddev->sysfs_active)
  		return -EBUSY;
  
  	if (!mddev->pers->quiesce) {
  		printk(KERN_WARNING "md: %s: %s does not support online personality change\n",
  		       mdname(mddev), mddev->pers->name);
  		return -EINVAL;
  	}
  
  	/* Now find the new personality */
  	if (len == 0 || len >= sizeof(clevel))
  		return -EINVAL;
  	strncpy(clevel, buf, len);
  	if (clevel[len-1] == '\n')
  		len--;
  	clevel[len] = 0;
  	if (strict_strtol(clevel, 10, &level))
  		level = LEVEL_NONE;
  
  	if (request_module("md-%s", clevel) != 0)
  		request_module("md-level-%s", clevel);
  	spin_lock(&pers_lock);
  	pers = find_pers(level, clevel);
  	if (!pers || !try_module_get(pers->owner)) {
  		spin_unlock(&pers_lock);
  		printk(KERN_WARNING "md: personality %s not loaded\n", clevel);
  		return -EINVAL;
  	}
  	spin_unlock(&pers_lock);
  
  	if (pers == mddev->pers) {
  		/* Nothing to do! */
  		module_put(pers->owner);
  		return rv;
  	}
  	if (!pers->takeover) {
  		module_put(pers->owner);
  		printk(KERN_WARNING "md: %s: %s does not support personality takeover\n",
  		       mdname(mddev), clevel);
  		return -EINVAL;
  	}
  
  	list_for_each_entry(rdev, &mddev->disks, same_set)
  		rdev->new_raid_disk = rdev->raid_disk;
  
  	/* ->takeover must set new_* and/or delta_disks
  	 * if it succeeds, and may set them when it fails.
  	 */
  	priv = pers->takeover(mddev);
  	if (IS_ERR(priv)) {
  		mddev->new_level = mddev->level;
  		mddev->new_layout = mddev->layout;
  		mddev->new_chunk_sectors = mddev->chunk_sectors;
  		mddev->raid_disks -= mddev->delta_disks;
  		mddev->delta_disks = 0;
  		module_put(pers->owner);
  		printk(KERN_WARNING "md: %s: %s would not accept array\n",
  		       mdname(mddev), clevel);
  		return PTR_ERR(priv);
  	}
  
  	/* Looks like we have a winner */
  	mddev_suspend(mddev);
  	mddev->pers->stop(mddev);
  
  	if (mddev->pers->sync_request == NULL &&
  	    pers->sync_request != NULL) {
  		/* need to add the md_redundancy_group */
  		if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
  			printk(KERN_WARNING
  			       "md: cannot register extra attributes for %s\n",
  			       mdname(mddev));
  		mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, NULL, "sync_action");
  	}
  	if (mddev->pers->sync_request != NULL &&
  	    pers->sync_request == NULL) {
  		/* need to remove the md_redundancy_group */
  		if (mddev->to_remove == NULL)
  			mddev->to_remove = &md_redundancy_group;
  	}
  
  	if (mddev->pers->sync_request == NULL &&
  	    mddev->external) {
  		/* We are converting from a no-redundancy array
  		 * to a redundancy array and metadata is managed
  		 * externally so we need to be sure that writes
  		 * won't block due to a need to transition
  		 *      clean->dirty
  		 * until external management is started.
  		 */
  		mddev->in_sync = 0;
  		mddev->safemode_delay = 0;
  		mddev->safemode = 0;
  	}
  
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		char nm[20];
  		if (rdev->raid_disk < 0)
  			continue;
  		if (rdev->new_raid_disk >= mddev->raid_disks)
  			rdev->new_raid_disk = -1;
  		if (rdev->new_raid_disk == rdev->raid_disk)
  			continue;
  		sprintf(nm, "rd%d", rdev->raid_disk);
  		sysfs_remove_link(&mddev->kobj, nm);
  	}
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		if (rdev->raid_disk < 0)
  			continue;
  		if (rdev->new_raid_disk == rdev->raid_disk)
  			continue;
  		rdev->raid_disk = rdev->new_raid_disk;
  		if (rdev->raid_disk < 0)
  			clear_bit(In_sync, &rdev->flags);
  		else {
  			char nm[20];
  			sprintf(nm, "rd%d", rdev->raid_disk);
  			if(sysfs_create_link(&mddev->kobj, &rdev->kobj, nm))
  				printk("md: cannot register %s for %s after level change\n",
  				       nm, mdname(mddev));
  		}
  	}
  
  	module_put(mddev->pers->owner);
  	mddev->pers = pers;
  	mddev->private = priv;
  	strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
  	mddev->level = mddev->new_level;
  	mddev->layout = mddev->new_layout;
  	mddev->chunk_sectors = mddev->new_chunk_sectors;
  	mddev->delta_disks = 0;
  	mddev->degraded = 0;
  	if (mddev->pers->sync_request == NULL) {
  		/* this is now an array without redundancy, so
  		 * it must always be in_sync
  		 */
  		mddev->in_sync = 1;
  		del_timer_sync(&mddev->safemode_timer);
  	}
  	pers->run(mddev);
  	mddev_resume(mddev);
  	set_bit(MD_CHANGE_DEVS, &mddev->flags);
  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	md_wakeup_thread(mddev->thread);
  	sysfs_notify(&mddev->kobj, NULL, "level");
  	md_new_event(mddev);
  	return rv;
  }
  
  static struct md_sysfs_entry md_level =
  __ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);
  
  static ssize_t
  layout_show(mddev_t *mddev, char *page)
  {
  	/* just a number, not meaningful for all levels */
  	if (mddev->reshape_position != MaxSector &&
  	    mddev->layout != mddev->new_layout)
  		return sprintf(page, "%d (%d)\n",
  			       mddev->new_layout, mddev->layout);
  	return sprintf(page, "%d\n", mddev->layout);
  }
  
  static ssize_t
  layout_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long n = simple_strtoul(buf, &e, 10);
  
  	if (!*buf || (*e && *e != '\n'))
  		return -EINVAL;
  
  	if (mddev->pers) {
  		int err;
  		if (mddev->pers->check_reshape == NULL)
  			return -EBUSY;
  		mddev->new_layout = n;
  		err = mddev->pers->check_reshape(mddev);
  		if (err) {
  			mddev->new_layout = mddev->layout;
  			return err;
  		}
  	} else {
  		mddev->new_layout = n;
  		if (mddev->reshape_position == MaxSector)
  			mddev->layout = n;
  	}
  	return len;
  }
  static struct md_sysfs_entry md_layout =
  __ATTR(layout, S_IRUGO|S_IWUSR, layout_show, layout_store);
  
  static ssize_t
  raid_disks_show(mddev_t *mddev, char *page)
  {
  	if (mddev->raid_disks == 0)
  		return 0;
  	if (mddev->reshape_position != MaxSector &&
  	    mddev->delta_disks != 0)
  		return sprintf(page, "%d (%d)\n", mddev->raid_disks,
  			       mddev->raid_disks - mddev->delta_disks);
  	return sprintf(page, "%d\n", mddev->raid_disks);
  }
  
  static int update_raid_disks(mddev_t *mddev, int raid_disks);
  
  static ssize_t
  raid_disks_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	int rv = 0;
  	unsigned long n = simple_strtoul(buf, &e, 10);
  
  	if (!*buf || (*e && *e != '\n'))
  		return -EINVAL;
  
  	if (mddev->pers)
  		rv = update_raid_disks(mddev, n);
  	else if (mddev->reshape_position != MaxSector) {
  		int olddisks = mddev->raid_disks - mddev->delta_disks;
  		mddev->delta_disks = n - olddisks;
  		mddev->raid_disks = n;
  	} else
  		mddev->raid_disks = n;
  	return rv ? rv : len;
  }
  static struct md_sysfs_entry md_raid_disks =
  __ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);
  
  static ssize_t
  chunk_size_show(mddev_t *mddev, char *page)
  {
  	if (mddev->reshape_position != MaxSector &&
  	    mddev->chunk_sectors != mddev->new_chunk_sectors)
  		return sprintf(page, "%d (%d)\n",
  			       mddev->new_chunk_sectors << 9,
  			       mddev->chunk_sectors << 9);
  	return sprintf(page, "%d\n", mddev->chunk_sectors << 9);
  }
  
  static ssize_t
  chunk_size_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long n = simple_strtoul(buf, &e, 10);
  
  	if (!*buf || (*e && *e != '\n'))
  		return -EINVAL;
  
  	if (mddev->pers) {
  		int err;
  		if (mddev->pers->check_reshape == NULL)
  			return -EBUSY;
  		mddev->new_chunk_sectors = n >> 9;
  		err = mddev->pers->check_reshape(mddev);
  		if (err) {
  			mddev->new_chunk_sectors = mddev->chunk_sectors;
  			return err;
  		}
  	} else {
  		mddev->new_chunk_sectors = n >> 9;
  		if (mddev->reshape_position == MaxSector)
  			mddev->chunk_sectors = n >> 9;
  	}
  	return len;
  }
  static struct md_sysfs_entry md_chunk_size =
  __ATTR(chunk_size, S_IRUGO|S_IWUSR, chunk_size_show, chunk_size_store);
  
  static ssize_t
  resync_start_show(mddev_t *mddev, char *page)
  {
  	if (mddev->recovery_cp == MaxSector)
  		return sprintf(page, "none\n");
  	return sprintf(page, "%llu\n", (unsigned long long)mddev->recovery_cp);
  }
  
  static ssize_t
  resync_start_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long long n = simple_strtoull(buf, &e, 10);
  
  	if (mddev->pers && !test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
  		return -EBUSY;
  	if (cmd_match(buf, "none"))
  		n = MaxSector;
  	else if (!*buf || (*e && *e != '\n'))
  		return -EINVAL;
  
  	mddev->recovery_cp = n;
  	return len;
  }
  static struct md_sysfs_entry md_resync_start =
  __ATTR(resync_start, S_IRUGO|S_IWUSR, resync_start_show, resync_start_store);
  
  /*
   * The array state can be:
   *
   * clear
   *     No devices, no size, no level
   *     Equivalent to STOP_ARRAY ioctl
   * inactive
   *     May have some settings, but array is not active
   *        all IO results in error
   *     When written, doesn't tear down array, but just stops it
   * suspended (not supported yet)
   *     All IO requests will block. The array can be reconfigured.
   *     Writing this, if accepted, will block until array is quiescent
   * readonly
   *     no resync can happen.  no superblocks get written.
   *     write requests fail
   * read-auto
   *     like readonly, but behaves like 'clean' on a write request.
   *
   * clean - no pending writes, but otherwise active.
   *     When written to inactive array, starts without resync
   *     If a write request arrives then
   *       if metadata is known, mark 'dirty' and switch to 'active'.
   *       if not known, block and switch to write-pending
   *     If written to an active array that has pending writes, then fails.
   * active
   *     fully active: IO and resync can be happening.
   *     When written to inactive array, starts with resync
   *
   * write-pending
   *     clean, but writes are blocked waiting for 'active' to be written.
   *
   * active-idle
   *     like active, but no writes have been seen for a while (100msec).
   *
   */
  enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
  		   write_pending, active_idle, bad_word};
  static char *array_states[] = {
  	"clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
  	"write-pending", "active-idle", NULL };
  
  static int match_word(const char *word, char **list)
  {
  	int n;
  	for (n=0; list[n]; n++)
  		if (cmd_match(word, list[n]))
  			break;
  	return n;
  }
  
  static ssize_t
  array_state_show(mddev_t *mddev, char *page)
  {
  	enum array_state st = inactive;
  
  	if (mddev->pers)
  		switch(mddev->ro) {
  		case 1:
  			st = readonly;
  			break;
  		case 2:
  			st = read_auto;
  			break;
  		case 0:
  			if (mddev->in_sync)
  				st = clean;
  			else if (test_bit(MD_CHANGE_PENDING, &mddev->flags))
  				st = write_pending;
  			else if (mddev->safemode)
  				st = active_idle;
  			else
  				st = active;
  		}
  	else {
  		if (list_empty(&mddev->disks) &&
  		    mddev->raid_disks == 0 &&
  		    mddev->dev_sectors == 0)
  			st = clear;
  		else
  			st = inactive;
  	}
  	return sprintf(page, "%s\n", array_states[st]);
  }
  
  static int do_md_stop(mddev_t * mddev, int ro, int is_open);
  static int md_set_readonly(mddev_t * mddev, int is_open);
  static int do_md_run(mddev_t * mddev);
  static int restart_array(mddev_t *mddev);
  
  static ssize_t
  array_state_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	int err = -EINVAL;
  	enum array_state st = match_word(buf, array_states);
  	switch(st) {
  	case bad_word:
  		break;
  	case clear:
  		/* stopping an active array */
  		if (atomic_read(&mddev->openers) > 0)
  			return -EBUSY;
  		err = do_md_stop(mddev, 0, 0);
  		break;
  	case inactive:
  		/* stopping an active array */
  		if (mddev->pers) {
  			if (atomic_read(&mddev->openers) > 0)
  				return -EBUSY;
  			err = do_md_stop(mddev, 2, 0);
  		} else
  			err = 0; /* already inactive */
  		break;
  	case suspended:
  		break; /* not supported yet */
  	case readonly:
  		if (mddev->pers)
  			err = md_set_readonly(mddev, 0);
  		else {
  			mddev->ro = 1;
  			set_disk_ro(mddev->gendisk, 1);
  			err = do_md_run(mddev);
  		}
  		break;
  	case read_auto:
  		if (mddev->pers) {
  			if (mddev->ro == 0)
  				err = md_set_readonly(mddev, 0);
  			else if (mddev->ro == 1)
  				err = restart_array(mddev);
  			if (err == 0) {
  				mddev->ro = 2;
  				set_disk_ro(mddev->gendisk, 0);
  			}
  		} else {
  			mddev->ro = 2;
  			err = do_md_run(mddev);
  		}
  		break;
  	case clean:
  		if (mddev->pers) {
  			restart_array(mddev);
  			spin_lock_irq(&mddev->write_lock);
  			if (atomic_read(&mddev->writes_pending) == 0) {
  				if (mddev->in_sync == 0) {
  					mddev->in_sync = 1;
  					if (mddev->safemode == 1)
  						mddev->safemode = 0;
  					set_bit(MD_CHANGE_CLEAN, &mddev->flags);
  				}
  				err = 0;
  			} else
  				err = -EBUSY;
  			spin_unlock_irq(&mddev->write_lock);
  		} else
  			err = -EINVAL;
  		break;
  	case active:
  		if (mddev->pers) {
  			restart_array(mddev);
  			clear_bit(MD_CHANGE_PENDING, &mddev->flags);
  			wake_up(&mddev->sb_wait);
  			err = 0;
  		} else {
  			mddev->ro = 0;
  			set_disk_ro(mddev->gendisk, 0);
  			err = do_md_run(mddev);
  		}
  		break;
  	case write_pending:
  	case active_idle:
  		/* these cannot be set */
  		break;
  	}
  	if (err)
  		return err;
  	else {
  		sysfs_notify_dirent_safe(mddev->sysfs_state);
  		return len;
  	}
  }
  static struct md_sysfs_entry md_array_state =
  __ATTR(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);
  
  static ssize_t
  max_corrected_read_errors_show(mddev_t *mddev, char *page) {
  	return sprintf(page, "%d\n",
  		       atomic_read(&mddev->max_corr_read_errors));
  }
  
  static ssize_t
  max_corrected_read_errors_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long n = simple_strtoul(buf, &e, 10);
  
  	if (*buf && (*e == 0 || *e == '\n')) {
  		atomic_set(&mddev->max_corr_read_errors, n);
  		return len;
  	}
  	return -EINVAL;
  }
  
  static struct md_sysfs_entry max_corr_read_errors =
  __ATTR(max_read_errors, S_IRUGO|S_IWUSR, max_corrected_read_errors_show,
  	max_corrected_read_errors_store);
  
  static ssize_t
  null_show(mddev_t *mddev, char *page)
  {
  	return -EINVAL;
  }
  
  static ssize_t
  new_dev_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	/* buf must be %d:%d\n? giving major and minor numbers */
  	/* The new device is added to the array.
  	 * If the array has a persistent superblock, we read the
  	 * superblock to initialise info and check validity.
  	 * Otherwise, only checking done is that in bind_rdev_to_array,
  	 * which mainly checks size.
  	 */
  	char *e;
  	int major = simple_strtoul(buf, &e, 10);
  	int minor;
  	dev_t dev;
  	mdk_rdev_t *rdev;
  	int err;
  
  	if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
  		return -EINVAL;
  	minor = simple_strtoul(e+1, &e, 10);
  	if (*e && *e != '\n')
  		return -EINVAL;
  	dev = MKDEV(major, minor);
  	if (major != MAJOR(dev) ||
  	    minor != MINOR(dev))
  		return -EOVERFLOW;
  
  	if (mddev->persistent) {
  		rdev = md_import_device(dev, mddev->major_version,
  					mddev->minor_version);
  		if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
  			mdk_rdev_t *rdev0 = list_entry(mddev->disks.next,
  						       mdk_rdev_t, same_set);
  			err = super_types[mddev->major_version]
  				.load_super(rdev, rdev0, mddev->minor_version);
  			if (err < 0)
  				goto out;
  		}
  	} else if (mddev->external)
  		rdev = md_import_device(dev, -2, -1);
  	else
  		rdev = md_import_device(dev, -1, -1);
  
  	if (IS_ERR(rdev))
  		return PTR_ERR(rdev);
  	err = bind_rdev_to_array(rdev, mddev);
   out:
  	if (err)
  		export_rdev(rdev);
  	return err ? err : len;
  }
  
  static struct md_sysfs_entry md_new_device =
  __ATTR(new_dev, S_IWUSR, null_show, new_dev_store);
  
  static ssize_t
  bitmap_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *end;
  	unsigned long chunk, end_chunk;
  
  	if (!mddev->bitmap)
  		goto out;
  	/* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
  	while (*buf) {
  		chunk = end_chunk = simple_strtoul(buf, &end, 0);
  		if (buf == end) break;
  		if (*end == '-') { /* range */
  			buf = end + 1;
  			end_chunk = simple_strtoul(buf, &end, 0);
  			if (buf == end) break;
  		}
  		if (*end && !isspace(*end)) break;
  		bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
  		buf = skip_spaces(end);
  	}
  	bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
  out:
  	return len;
  }
  
  static struct md_sysfs_entry md_bitmap =
  __ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);
  
  static ssize_t
  size_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%llu\n",
  		(unsigned long long)mddev->dev_sectors / 2);
  }
  
  static int update_size(mddev_t *mddev, sector_t num_sectors);
  
  static ssize_t
  size_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	/* If array is inactive, we can reduce the component size, but
  	 * not increase it (except from 0).
  	 * If array is active, we can try an on-line resize
  	 */
  	sector_t sectors;
  	int err = strict_blocks_to_sectors(buf, &sectors);
  
  	if (err < 0)
  		return err;
  	if (mddev->pers) {
  		err = update_size(mddev, sectors);
  		md_update_sb(mddev, 1);
  	} else {
  		if (mddev->dev_sectors == 0 ||
  		    mddev->dev_sectors > sectors)
  			mddev->dev_sectors = sectors;
  		else
  			err = -ENOSPC;
  	}
  	return err ? err : len;
  }
  
  static struct md_sysfs_entry md_size =
  __ATTR(component_size, S_IRUGO|S_IWUSR, size_show, size_store);
  
  /* Metdata version.
   * This is one of
   *   'none' for arrays with no metadata (good luck...)
   *   'external' for arrays with externally managed metadata,
   * or N.M for internally known formats
   */
  static ssize_t
  metadata_show(mddev_t *mddev, char *page)
  {
  	if (mddev->persistent)
  		return sprintf(page, "%d.%d\n",
  			       mddev->major_version, mddev->minor_version);
  	else if (mddev->external)
  		return sprintf(page, "external:%s\n", mddev->metadata_type);
  	else
  		return sprintf(page, "none\n");
  }
  
  static ssize_t
  metadata_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	int major, minor;
  	char *e;
  	/* Changing the details of 'external' metadata is
  	 * always permitted.  Otherwise there must be
  	 * no devices attached to the array.
  	 */
  	if (mddev->external && strncmp(buf, "external:", 9) == 0)
  		;
  	else if (!list_empty(&mddev->disks))
  		return -EBUSY;
  
  	if (cmd_match(buf, "none")) {
  		mddev->persistent = 0;
  		mddev->external = 0;
  		mddev->major_version = 0;
  		mddev->minor_version = 90;
  		return len;
  	}
  	if (strncmp(buf, "external:", 9) == 0) {
  		size_t namelen = len-9;
  		if (namelen >= sizeof(mddev->metadata_type))
  			namelen = sizeof(mddev->metadata_type)-1;
  		strncpy(mddev->metadata_type, buf+9, namelen);
  		mddev->metadata_type[namelen] = 0;
  		if (namelen && mddev->metadata_type[namelen-1] == '\n')
  			mddev->metadata_type[--namelen] = 0;
  		mddev->persistent = 0;
  		mddev->external = 1;
  		mddev->major_version = 0;
  		mddev->minor_version = 90;
  		return len;
  	}
  	major = simple_strtoul(buf, &e, 10);
  	if (e==buf || *e != '.')
  		return -EINVAL;
  	buf = e+1;
  	minor = simple_strtoul(buf, &e, 10);
  	if (e==buf || (*e && *e != '\n') )
  		return -EINVAL;
  	if (major >= ARRAY_SIZE(super_types) || super_types[major].name == NULL)
  		return -ENOENT;
  	mddev->major_version = major;
  	mddev->minor_version = minor;
  	mddev->persistent = 1;
  	mddev->external = 0;
  	return len;
  }
  
  static struct md_sysfs_entry md_metadata =
  __ATTR(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
  
  static ssize_t
  action_show(mddev_t *mddev, char *page)
  {
  	char *type = "idle";
  	if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
  		type = "frozen";
  	else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
  	    (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
  		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
  			type = "reshape";
  		else if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
  			if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
  				type = "resync";
  			else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
  				type = "check";
  			else
  				type = "repair";
  		} else if (test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
  			type = "recover";
  	}
  	return sprintf(page, "%s\n", type);
  }
  
  static void reap_sync_thread(mddev_t *mddev);
  
  static ssize_t
  action_store(mddev_t *mddev, const char *page, size_t len)
  {
  	if (!mddev->pers || !mddev->pers->sync_request)
  		return -EINVAL;
  
  	if (cmd_match(page, "frozen"))
  		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
  	else
  		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
  
  	if (cmd_match(page, "idle") || cmd_match(page, "frozen")) {
  		if (mddev->sync_thread) {
  			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
  			reap_sync_thread(mddev);
  		}
  	} else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
  		   test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
  		return -EBUSY;
  	else if (cmd_match(page, "resync"))
  		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	else if (cmd_match(page, "recover")) {
  		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
  		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	} else if (cmd_match(page, "reshape")) {
  		int err;
  		if (mddev->pers->start_reshape == NULL)
  			return -EINVAL;
  		err = mddev->pers->start_reshape(mddev);
  		if (err)
  			return err;
  		sysfs_notify(&mddev->kobj, NULL, "degraded");
  	} else {
  		if (cmd_match(page, "check"))
  			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
  		else if (!cmd_match(page, "repair"))
  			return -EINVAL;
  		set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
  		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
  	}
  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	md_wakeup_thread(mddev->thread);
  	sysfs_notify_dirent_safe(mddev->sysfs_action);
  	return len;
  }
  
  static ssize_t
  mismatch_cnt_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%llu\n",
  		       (unsigned long long) mddev->resync_mismatches);
  }
  
  static struct md_sysfs_entry md_scan_mode =
  __ATTR(sync_action, S_IRUGO|S_IWUSR, action_show, action_store);
  
  static struct md_sysfs_entry md_mismatches = __ATTR_RO(mismatch_cnt);
  
  static ssize_t
  sync_min_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%d (%s)\n", speed_min(mddev),
  		       mddev->sync_speed_min ? "local": "system");
  }
  
  static ssize_t
  sync_min_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	int min;
  	char *e;
  	if (strncmp(buf, "system", 6)==0) {
  		mddev->sync_speed_min = 0;
  		return len;
  	}
  	min = simple_strtoul(buf, &e, 10);
  	if (buf == e || (*e && *e != '\n') || min <= 0)
  		return -EINVAL;
  	mddev->sync_speed_min = min;
  	return len;
  }
  
  static struct md_sysfs_entry md_sync_min =
  __ATTR(sync_speed_min, S_IRUGO|S_IWUSR, sync_min_show, sync_min_store);
  
  static ssize_t
  sync_max_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%d (%s)\n", speed_max(mddev),
  		       mddev->sync_speed_max ? "local": "system");
  }
  
  static ssize_t
  sync_max_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	int max;
  	char *e;
  	if (strncmp(buf, "system", 6)==0) {
  		mddev->sync_speed_max = 0;
  		return len;
  	}
  	max = simple_strtoul(buf, &e, 10);
  	if (buf == e || (*e && *e != '\n') || max <= 0)
  		return -EINVAL;
  	mddev->sync_speed_max = max;
  	return len;
  }
  
  static struct md_sysfs_entry md_sync_max =
  __ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);
  
  static ssize_t
  degraded_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%d\n", mddev->degraded);
  }
  static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);
  
  static ssize_t
  sync_force_parallel_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%d\n", mddev->parallel_resync);
  }
  
  static ssize_t
  sync_force_parallel_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	long n;
  
  	if (strict_strtol(buf, 10, &n))
  		return -EINVAL;
  
  	if (n != 0 && n != 1)
  		return -EINVAL;
  
  	mddev->parallel_resync = n;
  
  	if (mddev->sync_thread)
  		wake_up(&resync_wait);
  
  	return len;
  }
  
  /* force parallel resync, even with shared block devices */
  static struct md_sysfs_entry md_sync_force_parallel =
  __ATTR(sync_force_parallel, S_IRUGO|S_IWUSR,
         sync_force_parallel_show, sync_force_parallel_store);
  
  static ssize_t
  sync_speed_show(mddev_t *mddev, char *page)
  {
  	unsigned long resync, dt, db;
  	if (mddev->curr_resync == 0)
  		return sprintf(page, "none\n");
  	resync = mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active);
  	dt = (jiffies - mddev->resync_mark) / HZ;
  	if (!dt) dt++;
  	db = resync - mddev->resync_mark_cnt;
  	return sprintf(page, "%lu\n", db/dt/2); /* K/sec */
  }
  
  static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);
  
  static ssize_t
  sync_completed_show(mddev_t *mddev, char *page)
  {
  	unsigned long long max_sectors, resync;
  
  	if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
  		return sprintf(page, "none\n");
  
  	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
  		max_sectors = mddev->resync_max_sectors;
  	else
  		max_sectors = mddev->dev_sectors;
  
  	resync = mddev->curr_resync_completed;
  	return sprintf(page, "%llu / %llu\n", resync, max_sectors);
  }
  
  static struct md_sysfs_entry md_sync_completed = __ATTR_RO(sync_completed);
  
  static ssize_t
  min_sync_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%llu\n",
  		       (unsigned long long)mddev->resync_min);
  }
  static ssize_t
  min_sync_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	unsigned long long min;
  	if (strict_strtoull(buf, 10, &min))
  		return -EINVAL;
  	if (min > mddev->resync_max)
  		return -EINVAL;
  	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
  		return -EBUSY;
  
  	/* Must be a multiple of chunk_size */
  	if (mddev->chunk_sectors) {
  		sector_t temp = min;
  		if (sector_div(temp, mddev->chunk_sectors))
  			return -EINVAL;
  	}
  	mddev->resync_min = min;
  
  	return len;
  }
  
  static struct md_sysfs_entry md_min_sync =
  __ATTR(sync_min, S_IRUGO|S_IWUSR, min_sync_show, min_sync_store);
  
  static ssize_t
  max_sync_show(mddev_t *mddev, char *page)
  {
  	if (mddev->resync_max == MaxSector)
  		return sprintf(page, "max\n");
  	else
  		return sprintf(page, "%llu\n",
  			       (unsigned long long)mddev->resync_max);
  }
  static ssize_t
  max_sync_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	if (strncmp(buf, "max", 3) == 0)
  		mddev->resync_max = MaxSector;
  	else {
  		unsigned long long max;
  		if (strict_strtoull(buf, 10, &max))
  			return -EINVAL;
  		if (max < mddev->resync_min)
  			return -EINVAL;
  		if (max < mddev->resync_max &&
  		    mddev->ro == 0 &&
  		    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
  			return -EBUSY;
  
  		/* Must be a multiple of chunk_size */
  		if (mddev->chunk_sectors) {
  			sector_t temp = max;
  			if (sector_div(temp, mddev->chunk_sectors))
  				return -EINVAL;
  		}
  		mddev->resync_max = max;
  	}
  	wake_up(&mddev->recovery_wait);
  	return len;
  }
  
  static struct md_sysfs_entry md_max_sync =
  __ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);
  
  static ssize_t
  suspend_lo_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);
  }
  
  static ssize_t
  suspend_lo_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long long new = simple_strtoull(buf, &e, 10);
  	unsigned long long old = mddev->suspend_lo;
  
  	if (mddev->pers == NULL ||
  	    mddev->pers->quiesce == NULL)
  		return -EINVAL;
  	if (buf == e || (*e && *e != '\n'))
  		return -EINVAL;
  
  	mddev->suspend_lo = new;
  	if (new >= old)
  		/* Shrinking suspended region */
  		mddev->pers->quiesce(mddev, 2);
  	else {
  		/* Expanding suspended region - need to wait */
  		mddev->pers->quiesce(mddev, 1);
  		mddev->pers->quiesce(mddev, 0);
  	}
  	return len;
  }
  static struct md_sysfs_entry md_suspend_lo =
  __ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);
  
  static ssize_t
  suspend_hi_show(mddev_t *mddev, char *page)
  {
  	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);
  }
  
  static ssize_t
  suspend_hi_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long long new = simple_strtoull(buf, &e, 10);
  	unsigned long long old = mddev->suspend_hi;
  
  	if (mddev->pers == NULL ||
  	    mddev->pers->quiesce == NULL)
  		return -EINVAL;
  	if (buf == e || (*e && *e != '\n'))
  		return -EINVAL;
  
  	mddev->suspend_hi = new;
  	if (new <= old)
  		/* Shrinking suspended region */
  		mddev->pers->quiesce(mddev, 2);
  	else {
  		/* Expanding suspended region - need to wait */
  		mddev->pers->quiesce(mddev, 1);
  		mddev->pers->quiesce(mddev, 0);
  	}
  	return len;
  }
  static struct md_sysfs_entry md_suspend_hi =
  __ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);
  
  static ssize_t
  reshape_position_show(mddev_t *mddev, char *page)
  {
  	if (mddev->reshape_position != MaxSector)
  		return sprintf(page, "%llu\n",
  			       (unsigned long long)mddev->reshape_position);
  	strcpy(page, "none\n");
  	return 5;
  }
  
  static ssize_t
  reshape_position_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	char *e;
  	unsigned long long new = simple_strtoull(buf, &e, 10);
  	if (mddev->pers)
  		return -EBUSY;
  	if (buf == e || (*e && *e != '\n'))
  		return -EINVAL;
  	mddev->reshape_position = new;
  	mddev->delta_disks = 0;
  	mddev->new_level = mddev->level;
  	mddev->new_layout = mddev->layout;
  	mddev->new_chunk_sectors = mddev->chunk_sectors;
  	return len;
  }
  
  static struct md_sysfs_entry md_reshape_position =
  __ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
         reshape_position_store);
  
  static ssize_t
  array_size_show(mddev_t *mddev, char *page)
  {
  	if (mddev->external_size)
  		return sprintf(page, "%llu\n",
  			       (unsigned long long)mddev->array_sectors/2);
  	else
  		return sprintf(page, "default\n");
  }
  
  static ssize_t
  array_size_store(mddev_t *mddev, const char *buf, size_t len)
  {
  	sector_t sectors;
  
  	if (strncmp(buf, "default", 7) == 0) {
  		if (mddev->pers)
  			sectors = mddev->pers->size(mddev, 0, 0);
  		else
  			sectors = mddev->array_sectors;
  
  		mddev->external_size = 0;
  	} else {
  		if (strict_blocks_to_sectors(buf, &sectors) < 0)
  			return -EINVAL;
  		if (mddev->pers && mddev->pers->size(mddev, 0, 0) < sectors)
  			return -E2BIG;
  
  		mddev->external_size = 1;
  	}
  
  	mddev->array_sectors = sectors;
  	if (mddev->pers) {
  		set_capacity(mddev->gendisk, mddev->array_sectors);
  		revalidate_disk(mddev->gendisk);
  	}
  	return len;
  }
  
  static struct md_sysfs_entry md_array_size =
  __ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
         array_size_store);
  
  static struct attribute *md_default_attrs[] = {
  	&md_level.attr,
  	&md_layout.attr,
  	&md_raid_disks.attr,
  	&md_chunk_size.attr,
  	&md_size.attr,
  	&md_resync_start.attr,
  	&md_metadata.attr,
  	&md_new_device.attr,
  	&md_safe_delay.attr,
  	&md_array_state.attr,
  	&md_reshape_position.attr,
  	&md_array_size.attr,
  	&max_corr_read_errors.attr,
  	NULL,
  };
  
  static struct attribute *md_redundancy_attrs[] = {
  	&md_scan_mode.attr,
  	&md_mismatches.attr,
  	&md_sync_min.attr,
  	&md_sync_max.attr,
  	&md_sync_speed.attr,
  	&md_sync_force_parallel.attr,
  	&md_sync_completed.attr,
  	&md_min_sync.attr,
  	&md_max_sync.attr,
  	&md_suspend_lo.attr,
  	&md_suspend_hi.attr,
  	&md_bitmap.attr,
  	&md_degraded.attr,
  	NULL,
  };
  static struct attribute_group md_redundancy_group = {
  	.name = NULL,
  	.attrs = md_redundancy_attrs,
  };
  
  static ssize_t
  md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
  {
  	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
  	mddev_t *mddev = container_of(kobj, struct mddev_s, kobj);
  	ssize_t rv;
  
  	if (!entry->show)
  		return -EIO;
  	rv = mddev_lock(mddev);
  	if (!rv) {
  		rv = entry->show(mddev, page);
  		mddev_unlock(mddev);
  	}
  	return rv;
  }
  
  static ssize_t
  md_attr_store(struct kobject *kobj, struct attribute *attr,
  	      const char *page, size_t length)
  {
  	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
  	mddev_t *mddev = container_of(kobj, struct mddev_s, kobj);
  	ssize_t rv;
  
  	if (!entry->store)
  		return -EIO;
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;
  	rv = mddev_lock(mddev);
  	if (mddev->hold_active == UNTIL_IOCTL)
  		mddev->hold_active = 0;
  	if (!rv) {
  		rv = entry->store(mddev, page, length);
  		mddev_unlock(mddev);
  	}
  	return rv;
  }
  
  static void md_free(struct kobject *ko)
  {
  	mddev_t *mddev = container_of(ko, mddev_t, kobj);
  
  	if (mddev->sysfs_state)
  		sysfs_put(mddev->sysfs_state);
  
  	if (mddev->gendisk) {
  		del_gendisk(mddev->gendisk);
  		put_disk(mddev->gendisk);
  	}
  	if (mddev->queue)
  		blk_cleanup_queue(mddev->queue);
  
  	kfree(mddev);
  }
  
  static const struct sysfs_ops md_sysfs_ops = {
  	.show	= md_attr_show,
  	.store	= md_attr_store,
  };
  static struct kobj_type md_ktype = {
  	.release	= md_free,
  	.sysfs_ops	= &md_sysfs_ops,
  	.default_attrs	= md_default_attrs,
  };
  
  int mdp_major = 0;
  
  static void mddev_delayed_delete(struct work_struct *ws)
  {
  	mddev_t *mddev = container_of(ws, mddev_t, del_work);
  
  	sysfs_remove_group(&mddev->kobj, &md_bitmap_group);
  	kobject_del(&mddev->kobj);
  	kobject_put(&mddev->kobj);
  }
  
  static int md_alloc(dev_t dev, char *name)
  {
  	static DEFINE_MUTEX(disks_mutex);
  	mddev_t *mddev = mddev_find(dev);
  	struct gendisk *disk;
  	int partitioned;
  	int shift;
  	int unit;
  	int error;
  
  	if (!mddev)
  		return -ENODEV;
  
  	partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
  	shift = partitioned ? MdpMinorShift : 0;
  	unit = MINOR(mddev->unit) >> shift;
  
  	/* wait for any previous instance of this device to be
  	 * completely removed (mddev_delayed_delete).
  	 */
  	flush_workqueue(md_misc_wq);
  
  	mutex_lock(&disks_mutex);
  	error = -EEXIST;
  	if (mddev->gendisk)
  		goto abort;
  
  	if (name) {
  		/* Need to ensure that 'name' is not a duplicate.
  		 */
  		mddev_t *mddev2;
  		spin_lock(&all_mddevs_lock);
  
  		list_for_each_entry(mddev2, &all_mddevs, all_mddevs)
  			if (mddev2->gendisk &&
  			    strcmp(mddev2->gendisk->disk_name, name) == 0) {
  				spin_unlock(&all_mddevs_lock);
  				goto abort;
  			}
  		spin_unlock(&all_mddevs_lock);
  	}
  
  	error = -ENOMEM;
  	mddev->queue = blk_alloc_queue(GFP_KERNEL);
  	if (!mddev->queue)
  		goto abort;
  	mddev->queue->queuedata = mddev;
  
  	blk_queue_make_request(mddev->queue, md_make_request);
  
  	disk = alloc_disk(1 << shift);
  	if (!disk) {
  		blk_cleanup_queue(mddev->queue);
  		mddev->queue = NULL;
  		goto abort;
  	}
  	disk->major = MAJOR(mddev->unit);
  	disk->first_minor = unit << shift;
  	if (name)
  		strcpy(disk->disk_name, name);
  	else if (partitioned)
  		sprintf(disk->disk_name, "md_d%d", unit);
  	else
  		sprintf(disk->disk_name, "md%d", unit);
  	disk->fops = &md_fops;
  	disk->private_data = mddev;
  	disk->queue = mddev->queue;
  	blk_queue_flush(mddev->queue, REQ_FLUSH | REQ_FUA);
  	/* Allow extended partitions.  This makes the
  	 * 'mdp' device redundant, but we can't really
  	 * remove it now.
  	 */
  	disk->flags |= GENHD_FL_EXT_DEVT;
  	mddev->gendisk = disk;
  	/* As soon as we call add_disk(), another thread could get
  	 * through to md_open, so make sure it doesn't get too far
  	 */
  	mutex_lock(&mddev->open_mutex);
  	add_disk(disk);
  
  	error = kobject_init_and_add(&mddev->kobj, &md_ktype,
  				     &disk_to_dev(disk)->kobj, "%s", "md");
  	if (error) {
  		/* This isn't possible, but as kobject_init_and_add is marked
  		 * __must_check, we must do something with the result
  		 */
  		printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
  		       disk->disk_name);
  		error = 0;
  	}
  	if (mddev->kobj.sd &&
  	    sysfs_create_group(&mddev->kobj, &md_bitmap_group))
  		printk(KERN_DEBUG "pointless warning\n");
  	mutex_unlock(&mddev->open_mutex);
   abort:
  	mutex_unlock(&disks_mutex);
  	if (!error && mddev->kobj.sd) {
  		kobject_uevent(&mddev->kobj, KOBJ_ADD);
  		mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
  	}
  	mddev_put(mddev);
  	return error;
  }
  
  static struct kobject *md_probe(dev_t dev, int *part, void *data)
  {
  	md_alloc(dev, NULL);
  	return NULL;
  }
  
  static int add_named_array(const char *val, struct kernel_param *kp)
  {
  	/* val must be "md_*" where * is not all digits.
  	 * We allocate an array with a large free minor number, and
  	 * set the name to val.  val must not already be an active name.
  	 */
  	int len = strlen(val);
  	char buf[DISK_NAME_LEN];
  
  	while (len && val[len-1] == '\n')
  		len--;
  	if (len >= DISK_NAME_LEN)
  		return -E2BIG;
  	strlcpy(buf, val, len+1);
  	if (strncmp(buf, "md_", 3) != 0)
  		return -EINVAL;
  	return md_alloc(0, buf);
  }
  
  static void md_safemode_timeout(unsigned long data)
  {
  	mddev_t *mddev = (mddev_t *) data;
  
  	if (!atomic_read(&mddev->writes_pending)) {
  		mddev->safemode = 1;
  		if (mddev->external)
  			sysfs_notify_dirent_safe(mddev->sysfs_state);
  	}
  	md_wakeup_thread(mddev->thread);
  }
  
  static int start_dirty_degraded;
  
  int md_run(mddev_t *mddev)
  {
  	int err;
  	mdk_rdev_t *rdev;
  	struct mdk_personality *pers;
  
  	if (list_empty(&mddev->disks))
  		/* cannot run an array with no devices.. */
  		return -EINVAL;
  
  	if (mddev->pers)
  		return -EBUSY;
  	/* Cannot run until previous stop completes properly */
  	if (mddev->sysfs_active)
  		return -EBUSY;
  
  	/*
  	 * Analyze all RAID superblock(s)
  	 */
  	if (!mddev->raid_disks) {
  		if (!mddev->persistent)
  			return -EINVAL;
  		analyze_sbs(mddev);
  	}
  
  	if (mddev->level != LEVEL_NONE)
  		request_module("md-level-%d", mddev->level);
  	else if (mddev->clevel[0])
  		request_module("md-%s", mddev->clevel);
  
  	/*
  	 * Drop all container device buffers, from now on
  	 * the only valid external interface is through the md
  	 * device.
  	 */
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		if (test_bit(Faulty, &rdev->flags))
  			continue;
  		sync_blockdev(rdev->bdev);
  		invalidate_bdev(rdev->bdev);
  
  		/* perform some consistency tests on the device.
  		 * We don't want the data to overlap the metadata,
  		 * Internal Bitmap issues have been handled elsewhere.
  		 */
  		if (rdev->meta_bdev) {
  			/* Nothing to check */;
  		} else if (rdev->data_offset < rdev->sb_start) {
  			if (mddev->dev_sectors &&
  			    rdev->data_offset + mddev->dev_sectors
  			    > rdev->sb_start) {
  				printk("md: %s: data overlaps metadata\n",
  				       mdname(mddev));
  				return -EINVAL;
  			}
  		} else {
  			if (rdev->sb_start + rdev->sb_size/512
  			    > rdev->data_offset) {
  				printk("md: %s: metadata overlaps data\n",
  				       mdname(mddev));
  				return -EINVAL;
  			}
  		}
  		sysfs_notify_dirent_safe(rdev->sysfs_state);
  	}
  
  	if (mddev->bio_set == NULL)
  		mddev->bio_set = bioset_create(BIO_POOL_SIZE, sizeof(mddev));
  
  	spin_lock(&pers_lock);
  	pers = find_pers(mddev->level, mddev->clevel);
  	if (!pers || !try_module_get(pers->owner)) {
  		spin_unlock(&pers_lock);
  		if (mddev->level != LEVEL_NONE)
  			printk(KERN_WARNING "md: personality for level %d is not loaded!\n",
  			       mddev->level);
  		else
  			printk(KERN_WARNING "md: personality for level %s is not loaded!\n",
  			       mddev->clevel);
  		return -EINVAL;
  	}
  	mddev->pers = pers;
  	spin_unlock(&pers_lock);
  	if (mddev->level != pers->level) {
  		mddev->level = pers->level;
  		mddev->new_level = pers->level;
  	}
  	strlcpy(mddev->clevel, pers->name, sizeof(mddev->clevel));
  
  	if (mddev->reshape_position != MaxSector &&
  	    pers->start_reshape == NULL) {
  		/* This personality cannot handle reshaping... */
  		mddev->pers = NULL;
  		module_put(pers->owner);
  		return -EINVAL;
  	}
  
  	if (pers->sync_request) {
  		/* Warn if this is a potentially silly
  		 * configuration.
  		 */
  		char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
  		mdk_rdev_t *rdev2;
  		int warned = 0;
  
  		list_for_each_entry(rdev, &mddev->disks, same_set)
  			list_for_each_entry(rdev2, &mddev->disks, same_set) {
  				if (rdev < rdev2 &&
  				    rdev->bdev->bd_contains ==
  				    rdev2->bdev->bd_contains) {
  					printk(KERN_WARNING
  					       "%s: WARNING: %s appears to be"
  					       " on the same physical disk as"
  					       " %s.\n",
  					       mdname(mddev),
  					       bdevname(rdev->bdev,b),
  					       bdevname(rdev2->bdev,b2));
  					warned = 1;
  				}
  			}
  
  		if (warned)
  			printk(KERN_WARNING
  			       "True protection against single-disk"
  			       " failure might be compromised.\n");
  	}
  
  	mddev->recovery = 0;
  	/* may be over-ridden by personality */
  	mddev->resync_max_sectors = mddev->dev_sectors;
  
  	mddev->ok_start_degraded = start_dirty_degraded;
  
  	if (start_readonly && mddev->ro == 0)
  		mddev->ro = 2; /* read-only, but switch on first write */
  
  	err = mddev->pers->run(mddev);
  	if (err)
  		printk(KERN_ERR "md: pers->run() failed ...\n");
  	else if (mddev->pers->size(mddev, 0, 0) < mddev->array_sectors) {
  		WARN_ONCE(!mddev->external_size, "%s: default size too small,"
  			  " but 'external_size' not in effect?\n", __func__);
  		printk(KERN_ERR
  		       "md: invalid array_size %llu > default size %llu\n",
  		       (unsigned long long)mddev->array_sectors / 2,
  		       (unsigned long long)mddev->pers->size(mddev, 0, 0) / 2);
  		err = -EINVAL;
  		mddev->pers->stop(mddev);
  	}
  	if (err == 0 && mddev->pers->sync_request) {
  		err = bitmap_create(mddev);
  		if (err) {
  			printk(KERN_ERR "%s: failed to create bitmap (%d)\n",
  			       mdname(mddev), err);
  			mddev->pers->stop(mddev);
  		}
  	}
  	if (err) {
  		module_put(mddev->pers->owner);
  		mddev->pers = NULL;
  		bitmap_destroy(mddev);
  		return err;
  	}
  	if (mddev->pers->sync_request) {
  		if (mddev->kobj.sd &&
  		    sysfs_create_group(&mddev->kobj, &md_redundancy_group))
  			printk(KERN_WARNING
  			       "md: cannot register extra attributes for %s\n",
  			       mdname(mddev));
  		mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
  	} else if (mddev->ro == 2) /* auto-readonly not meaningful */
  		mddev->ro = 0;
  
   	atomic_set(&mddev->writes_pending,0);
  	atomic_set(&mddev->max_corr_read_errors,
  		   MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
  	mddev->safemode = 0;
  	mddev->safemode_timer.function = md_safemode_timeout;
  	mddev->safemode_timer.data = (unsigned long) mddev;
  	mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */
  	mddev->in_sync = 1;
  	smp_wmb();
  	mddev->ready = 1;
  	list_for_each_entry(rdev, &mddev->disks, same_set)
  		if (rdev->raid_disk >= 0) {
  			char nm[20];
  			sprintf(nm, "rd%d", rdev->raid_disk);
  			if (sysfs_create_link(&mddev->kobj, &rdev->kobj, nm))
  				/* failure here is OK */;
  		}
  
  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  
  	if (mddev->flags)
  		md_update_sb(mddev, 0);
  
  	md_new_event(mddev);
  	sysfs_notify_dirent_safe(mddev->sysfs_state);
  	sysfs_notify_dirent_safe(mddev->sysfs_action);
  	sysfs_notify(&mddev->kobj, NULL, "degraded");
  	return 0;
  }
  EXPORT_SYMBOL_GPL(md_run);
  
  static int do_md_run(mddev_t *mddev)
  {
  	int err;
  
  	err = md_run(mddev);
  	if (err)
  		goto out;
  	err = bitmap_load(mddev);
  	if (err) {
  		bitmap_destroy(mddev);
  		goto out;
  	}
  
  	md_wakeup_thread(mddev->thread);
  	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
  
  	set_capacity(mddev->gendisk, mddev->array_sectors);
  	revalidate_disk(mddev->gendisk);
  	mddev->changed = 1;
  	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
  out:
  	return err;
  }
  
  static int restart_array(mddev_t *mddev)
  {
  	struct gendisk *disk = mddev->gendisk;
  
  	/* Complain if it has no devices */
  	if (list_empty(&mddev->disks))
  		return -ENXIO;
  	if (!mddev->pers)
  		return -EINVAL;
  	if (!mddev->ro)
  		return -EBUSY;
  	mddev->safemode = 0;
  	mddev->ro = 0;
  	set_disk_ro(disk, 0);
  	printk(KERN_INFO "md: %s switched to read-write mode.\n",
  		mdname(mddev));
  	/* Kick recovery or resync if necessary */
  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	md_wakeup_thread(mddev->thread);
  	md_wakeup_thread(mddev->sync_thread);
  	sysfs_notify_dirent_safe(mddev->sysfs_state);
  	return 0;
  }
  
  /* similar to deny_write_access, but accounts for our holding a reference
   * to the file ourselves */
  static int deny_bitmap_write_access(struct file * file)
  {
  	struct inode *inode = file->f_mapping->host;
  
  	spin_lock(&inode->i_lock);
  	if (atomic_read(&inode->i_writecount) > 1) {
  		spin_unlock(&inode->i_lock);
  		return -ETXTBSY;
  	}
  	atomic_set(&inode->i_writecount, -1);
  	spin_unlock(&inode->i_lock);
  
  	return 0;
  }
  
  void restore_bitmap_write_access(struct file *file)
  {
  	struct inode *inode = file->f_mapping->host;
  
  	spin_lock(&inode->i_lock);
  	atomic_set(&inode->i_writecount, 1);
  	spin_unlock(&inode->i_lock);
  }
  
  static void md_clean(mddev_t *mddev)
  {
  	mddev->array_sectors = 0;
  	mddev->external_size = 0;
  	mddev->dev_sectors = 0;
  	mddev->raid_disks = 0;
  	mddev->recovery_cp = 0;
  	mddev->resync_min = 0;
  	mddev->resync_max = MaxSector;
  	mddev->reshape_position = MaxSector;
  	mddev->external = 0;
  	mddev->persistent = 0;
  	mddev->level = LEVEL_NONE;
  	mddev->clevel[0] = 0;
  	mddev->flags = 0;
  	mddev->ro = 0;
  	mddev->metadata_type[0] = 0;
  	mddev->chunk_sectors = 0;
  	mddev->ctime = mddev->utime = 0;
  	mddev->layout = 0;
  	mddev->max_disks = 0;
  	mddev->events = 0;
  	mddev->can_decrease_events = 0;
  	mddev->delta_disks = 0;
  	mddev->new_level = LEVEL_NONE;
  	mddev->new_layout = 0;
  	mddev->new_chunk_sectors = 0;
  	mddev->curr_resync = 0;
  	mddev->resync_mismatches = 0;
  	mddev->suspend_lo = mddev->suspend_hi = 0;
  	mddev->sync_speed_min = mddev->sync_speed_max = 0;
  	mddev->recovery = 0;
  	mddev->in_sync = 0;
  	mddev->changed = 0;
  	mddev->degraded = 0;
  	mddev->safemode = 0;
  	mddev->bitmap_info.offset = 0;
  	mddev->bitmap_info.default_offset = 0;
  	mddev->bitmap_info.chunksize = 0;
  	mddev->bitmap_info.daemon_sleep = 0;
  	mddev->bitmap_info.max_write_behind = 0;
  }
  
  static void __md_stop_writes(mddev_t *mddev)
  {
  	if (mddev->sync_thread) {
  		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
  		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
  		reap_sync_thread(mddev);
  	}
  
  	del_timer_sync(&mddev->safemode_timer);
  
  	bitmap_flush(mddev);
  	md_super_wait(mddev);
  
  	if (!mddev->in_sync || mddev->flags) {
  		/* mark array as shutdown cleanly */
  		mddev->in_sync = 1;
  		md_update_sb(mddev, 1);
  	}
  }
  
  void md_stop_writes(mddev_t *mddev)
  {
  	mddev_lock(mddev);
  	__md_stop_writes(mddev);
  	mddev_unlock(mddev);
  }
  EXPORT_SYMBOL_GPL(md_stop_writes);
  
  void md_stop(mddev_t *mddev)
  {
  	mddev->ready = 0;
  	mddev->pers->stop(mddev);
  	if (mddev->pers->sync_request && mddev->to_remove == NULL)
  		mddev->to_remove = &md_redundancy_group;
  	module_put(mddev->pers->owner);
  	mddev->pers = NULL;
  	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
  }
  EXPORT_SYMBOL_GPL(md_stop);
  
  static int md_set_readonly(mddev_t *mddev, int is_open)
  {
  	int err = 0;
  	mutex_lock(&mddev->open_mutex);
  	if (atomic_read(&mddev->openers) > is_open) {
  		printk("md: %s still in use.\n",mdname(mddev));
  		err = -EBUSY;
  		goto out;
  	}
  	if (mddev->pers) {
  		__md_stop_writes(mddev);
  
  		err  = -ENXIO;
  		if (mddev->ro==1)
  			goto out;
  		mddev->ro = 1;
  		set_disk_ro(mddev->gendisk, 1);
  		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
  		sysfs_notify_dirent_safe(mddev->sysfs_state);
  		err = 0;
  	}
  out:
  	mutex_unlock(&mddev->open_mutex);
  	return err;
  }
  
  /* mode:
   *   0 - completely stop and dis-assemble array
   *   2 - stop but do not disassemble array
   */
  static int do_md_stop(mddev_t * mddev, int mode, int is_open)
  {
  	struct gendisk *disk = mddev->gendisk;
  	mdk_rdev_t *rdev;
  
  	mutex_lock(&mddev->open_mutex);
  	if (atomic_read(&mddev->openers) > is_open ||
  	    mddev->sysfs_active) {
  		printk("md: %s still in use.\n",mdname(mddev));
  		mutex_unlock(&mddev->open_mutex);
  		return -EBUSY;
  	}
  
  	if (mddev->pers) {
  		if (mddev->ro)
  			set_disk_ro(disk, 0);
  
  		__md_stop_writes(mddev);
  		md_stop(mddev);
  		mddev->queue->merge_bvec_fn = NULL;
  		mddev->queue->backing_dev_info.congested_fn = NULL;
  
  		/* tell userspace to handle 'inactive' */
  		sysfs_notify_dirent_safe(mddev->sysfs_state);
  
  		list_for_each_entry(rdev, &mddev->disks, same_set)
  			if (rdev->raid_disk >= 0) {
  				char nm[20];
  				sprintf(nm, "rd%d", rdev->raid_disk);
  				sysfs_remove_link(&mddev->kobj, nm);
  			}
  
  		set_capacity(disk, 0);
  		mutex_unlock(&mddev->open_mutex);
  		mddev->changed = 1;
  		revalidate_disk(disk);
  
  		if (mddev->ro)
  			mddev->ro = 0;
  	} else
  		mutex_unlock(&mddev->open_mutex);
  	/*
  	 * Free resources if final stop
  	 */
  	if (mode == 0) {
  		printk(KERN_INFO "md: %s stopped.\n", mdname(mddev));
  
  		bitmap_destroy(mddev);
  		if (mddev->bitmap_info.file) {
  			restore_bitmap_write_access(mddev->bitmap_info.file);
  			fput(mddev->bitmap_info.file);
  			mddev->bitmap_info.file = NULL;
  		}
  		mddev->bitmap_info.offset = 0;
  
  		export_array(mddev);
  
  		md_clean(mddev);
  		kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
  		if (mddev->hold_active == UNTIL_STOP)
  			mddev->hold_active = 0;
  	}
  	blk_integrity_unregister(disk);
  	md_new_event(mddev);
  	sysfs_notify_dirent_safe(mddev->sysfs_state);
  	return 0;
  }
  
  #ifndef MODULE
  static void autorun_array(mddev_t *mddev)
  {
  	mdk_rdev_t *rdev;
  	int err;
  
  	if (list_empty(&mddev->disks))
  		return;
  
  	printk(KERN_INFO "md: running: ");
  
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		char b[BDEVNAME_SIZE];
  		printk("<%s>", bdevname(rdev->bdev,b));
  	}
  	printk("\n");
  
  	err = do_md_run(mddev);
  	if (err) {
  		printk(KERN_WARNING "md: do_md_run() returned %d\n", err);
  		do_md_stop(mddev, 0, 0);
  	}
  }
  
  /*
   * lets try to run arrays based on all disks that have arrived
   * until now. (those are in pending_raid_disks)
   *
   * the method: pick the first pending disk, collect all disks with
   * the same UUID, remove all from the pending list and put them into
   * the 'same_array' list. Then order this list based on superblock
   * update time (freshest comes first), kick out 'old' disks and
   * compare superblocks. If everything's fine then run it.
   *
   * If "unit" is allocated, then bump its reference count
   */
  static void autorun_devices(int part)
  {
  	mdk_rdev_t *rdev0, *rdev, *tmp;
  	mddev_t *mddev;
  	char b[BDEVNAME_SIZE];
  
  	printk(KERN_INFO "md: autorun ...\n");
  	while (!list_empty(&pending_raid_disks)) {
  		int unit;
  		dev_t dev;
  		LIST_HEAD(candidates);
  		rdev0 = list_entry(pending_raid_disks.next,
  					 mdk_rdev_t, same_set);
  
  		printk(KERN_INFO "md: considering %s ...\n",
  			bdevname(rdev0->bdev,b));
  		INIT_LIST_HEAD(&candidates);
  		rdev_for_each_list(rdev, tmp, &pending_raid_disks)
  			if (super_90_load(rdev, rdev0, 0) >= 0) {
  				printk(KERN_INFO "md:  adding %s ...\n",
  					bdevname(rdev->bdev,b));
  				list_move(&rdev->same_set, &candidates);
  			}
  		/*
  		 * now we have a set of devices, with all of them having
  		 * mostly sane superblocks. It's time to allocate the
  		 * mddev.
  		 */
  		if (part) {
  			dev = MKDEV(mdp_major,
  				    rdev0->preferred_minor << MdpMinorShift);
  			unit = MINOR(dev) >> MdpMinorShift;
  		} else {
  			dev = MKDEV(MD_MAJOR, rdev0->preferred_minor);
  			unit = MINOR(dev);
  		}
  		if (rdev0->preferred_minor != unit) {
  			printk(KERN_INFO "md: unit number in %s is bad: %d\n",
  			       bdevname(rdev0->bdev, b), rdev0->preferred_minor);
  			break;
  		}
  
  		md_probe(dev, NULL, NULL);
  		mddev = mddev_find(dev);
  		if (!mddev || !mddev->gendisk) {
  			if (mddev)
  				mddev_put(mddev);
  			printk(KERN_ERR
  				"md: cannot allocate memory for md drive.\n");
  			break;
  		}
  		if (mddev_lock(mddev))
  			printk(KERN_WARNING "md: %s locked, cannot run\n",
  			       mdname(mddev));
  		else if (mddev->raid_disks || mddev->major_version
  			 || !list_empty(&mddev->disks)) {
  			printk(KERN_WARNING
  				"md: %s already running, cannot run %s\n",
  				mdname(mddev), bdevname(rdev0->bdev,b));
  			mddev_unlock(mddev);
  		} else {
  			printk(KERN_INFO "md: created %s\n", mdname(mddev));
  			mddev->persistent = 1;
  			rdev_for_each_list(rdev, tmp, &candidates) {
  				list_del_init(&rdev->same_set);
  				if (bind_rdev_to_array(rdev, mddev))
  					export_rdev(rdev);
  			}
  			autorun_array(mddev);
  			mddev_unlock(mddev);
  		}
  		/* on success, candidates will be empty, on error
  		 * it won't...
  		 */
  		rdev_for_each_list(rdev, tmp, &candidates) {
  			list_del_init(&rdev->same_set);
  			export_rdev(rdev);
  		}
  		mddev_put(mddev);
  	}
  	printk(KERN_INFO "md: ... autorun DONE.\n");
  }
  #endif /* !MODULE */
  
  static int get_version(void __user * arg)
  {
  	mdu_version_t ver;
  
  	ver.major = MD_MAJOR_VERSION;
  	ver.minor = MD_MINOR_VERSION;
  	ver.patchlevel = MD_PATCHLEVEL_VERSION;
  
  	if (copy_to_user(arg, &ver, sizeof(ver)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int get_array_info(mddev_t * mddev, void __user * arg)
  {
  	mdu_array_info_t info;
  	int nr,working,insync,failed,spare;
  	mdk_rdev_t *rdev;
  
  	nr=working=insync=failed=spare=0;
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		nr++;
  		if (test_bit(Faulty, &rdev->flags))
  			failed++;
  		else {
  			working++;
  			if (test_bit(In_sync, &rdev->flags))
  				insync++;
  			else
  				spare++;
  		}
  	}
  
  	info.major_version = mddev->major_version;
  	info.minor_version = mddev->minor_version;
  	info.patch_version = MD_PATCHLEVEL_VERSION;
  	info.ctime         = mddev->ctime;
  	info.level         = mddev->level;
  	info.size          = mddev->dev_sectors / 2;
  	if (info.size != mddev->dev_sectors / 2) /* overflow */
  		info.size = -1;
  	info.nr_disks      = nr;
  	info.raid_disks    = mddev->raid_disks;
  	info.md_minor      = mddev->md_minor;
  	info.not_persistent= !mddev->persistent;
  
  	info.utime         = mddev->utime;
  	info.state         = 0;
  	if (mddev->in_sync)
  		info.state = (1<<MD_SB_CLEAN);
  	if (mddev->bitmap && mddev->bitmap_info.offset)
  		info.state = (1<<MD_SB_BITMAP_PRESENT);
  	info.active_disks  = insync;
  	info.working_disks = working;
  	info.failed_disks  = failed;
  	info.spare_disks   = spare;
  
  	info.layout        = mddev->layout;
  	info.chunk_size    = mddev->chunk_sectors << 9;
  
  	if (copy_to_user(arg, &info, sizeof(info)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int get_bitmap_file(mddev_t * mddev, void __user * arg)
  {
  	mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
  	char *ptr, *buf = NULL;
  	int err = -ENOMEM;
  
  	if (md_allow_write(mddev))
  		file = kmalloc(sizeof(*file), GFP_NOIO);
  	else
  		file = kmalloc(sizeof(*file), GFP_KERNEL);
  
  	if (!file)
  		goto out;
  
  	/* bitmap disabled, zero the first byte and copy out */
  	if (!mddev->bitmap || !mddev->bitmap->file) {
  		file->pathname[0] = '\0';
  		goto copy_out;
  	}
  
  	buf = kmalloc(sizeof(file->pathname), GFP_KERNEL);
  	if (!buf)
  		goto out;
  
  	ptr = d_path(&mddev->bitmap->file->f_path, buf, sizeof(file->pathname));
  	if (IS_ERR(ptr))
  		goto out;
  
  	strcpy(file->pathname, ptr);
  
  copy_out:
  	err = 0;
  	if (copy_to_user(arg, file, sizeof(*file)))
  		err = -EFAULT;
  out:
  	kfree(buf);
  	kfree(file);
  	return err;
  }
  
  static int get_disk_info(mddev_t * mddev, void __user * arg)
  {
  	mdu_disk_info_t info;
  	mdk_rdev_t *rdev;
  
  	if (copy_from_user(&info, arg, sizeof(info)))
  		return -EFAULT;
  
  	rdev = find_rdev_nr(mddev, info.number);
  	if (rdev) {
  		info.major = MAJOR(rdev->bdev->bd_dev);
  		info.minor = MINOR(rdev->bdev->bd_dev);
  		info.raid_disk = rdev->raid_disk;
  		info.state = 0;
  		if (test_bit(Faulty, &rdev->flags))
  			info.state |= (1<<MD_DISK_FAULTY);
  		else if (test_bit(In_sync, &rdev->flags)) {
  			info.state |= (1<<MD_DISK_ACTIVE);
  			info.state |= (1<<MD_DISK_SYNC);
  		}
  		if (test_bit(WriteMostly, &rdev->flags))
  			info.state |= (1<<MD_DISK_WRITEMOSTLY);
  	} else {
  		info.major = info.minor = 0;
  		info.raid_disk = -1;
  		info.state = (1<<MD_DISK_REMOVED);
  	}
  
  	if (copy_to_user(arg, &info, sizeof(info)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
  {
  	char b[BDEVNAME_SIZE], b2[BDEVNAME_SIZE];
  	mdk_rdev_t *rdev;
  	dev_t dev = MKDEV(info->major,info->minor);
  
  	if (info->major != MAJOR(dev) || info->minor != MINOR(dev))
  		return -EOVERFLOW;
  
  	if (!mddev->raid_disks) {
  		int err;
  		/* expecting a device which has a superblock */
  		rdev = md_import_device(dev, mddev->major_version, mddev->minor_version);
  		if (IS_ERR(rdev)) {
  			printk(KERN_WARNING
  				"md: md_import_device returned %ld\n",
  				PTR_ERR(rdev));
  			return PTR_ERR(rdev);
  		}
  		if (!list_empty(&mddev->disks)) {
  			mdk_rdev_t *rdev0 = list_entry(mddev->disks.next,
  							mdk_rdev_t, same_set);
  			err = super_types[mddev->major_version]
  				.load_super(rdev, rdev0, mddev->minor_version);
  			if (err < 0) {
  				printk(KERN_WARNING
  					"md: %s has different UUID to %s\n",
  					bdevname(rdev->bdev,b),
  					bdevname(rdev0->bdev,b2));
  				export_rdev(rdev);
  				return -EINVAL;
  			}
  		}
  		err = bind_rdev_to_array(rdev, mddev);
  		if (err)
  			export_rdev(rdev);
  		return err;
  	}
  
  	/*
  	 * add_new_disk can be used once the array is assembled
  	 * to add "hot spares".  They must already have a superblock
  	 * written
  	 */
  	if (mddev->pers) {
  		int err;
  		if (!mddev->pers->hot_add_disk) {
  			printk(KERN_WARNING
  				"%s: personality does not support diskops!\n",
  			       mdname(mddev));
  			return -EINVAL;
  		}
  		if (mddev->persistent)
  			rdev = md_import_device(dev, mddev->major_version,
  						mddev->minor_version);
  		else
  			rdev = md_import_device(dev, -1, -1);
  		if (IS_ERR(rdev)) {
  			printk(KERN_WARNING
  				"md: md_import_device returned %ld\n",
  				PTR_ERR(rdev));
  			return PTR_ERR(rdev);
  		}
  		/* set saved_raid_disk if appropriate */
  		if (!mddev->persistent) {
  			if (info->state & (1<<MD_DISK_SYNC)  &&
  			    info->raid_disk < mddev->raid_disks) {
  				rdev->raid_disk = info->raid_disk;
  				set_bit(In_sync, &rdev->flags);
  			} else
  				rdev->raid_disk = -1;
  		} else
  			super_types[mddev->major_version].
  				validate_super(mddev, rdev);
  		if ((info->state & (1<<MD_DISK_SYNC)) &&
  		    (!test_bit(In_sync, &rdev->flags) ||
  		     rdev->raid_disk != info->raid_disk)) {
  			/* This was a hot-add request, but events doesn't
  			 * match, so reject it.
  			 */
  			export_rdev(rdev);
  			return -EINVAL;
  		}
  
  		if (test_bit(In_sync, &rdev->flags))
  			rdev->saved_raid_disk = rdev->raid_disk;
  		else
  			rdev->saved_raid_disk = -1;
  
  		clear_bit(In_sync, &rdev->flags); /* just to be sure */
  		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
  			set_bit(WriteMostly, &rdev->flags);
  		else
  			clear_bit(WriteMostly, &rdev->flags);
  
  		rdev->raid_disk = -1;
  		err = bind_rdev_to_array(rdev, mddev);
  		if (!err && !mddev->pers->hot_remove_disk) {
  			/* If there is hot_add_disk but no hot_remove_disk
  			 * then added disks for geometry changes,
  			 * and should be added immediately.
  			 */
  			super_types[mddev->major_version].
  				validate_super(mddev, rdev);
  			err = mddev->pers->hot_add_disk(mddev, rdev);
  			if (err)
  				unbind_rdev_from_array(rdev);
  		}
  		if (err)
  			export_rdev(rdev);
  		else
  			sysfs_notify_dirent_safe(rdev->sysfs_state);
  
  		md_update_sb(mddev, 1);
  		if (mddev->degraded)
  			set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
  		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  		if (!err)
  			md_new_event(mddev);
  		md_wakeup_thread(mddev->thread);
  		return err;
  	}
  
  	/* otherwise, add_new_disk is only allowed
  	 * for major_version==0 superblocks
  	 */
  	if (mddev->major_version != 0) {
  		printk(KERN_WARNING "%s: ADD_NEW_DISK not supported\n",
  		       mdname(mddev));
  		return -EINVAL;
  	}
  
  	if (!(info->state & (1<<MD_DISK_FAULTY))) {
  		int err;
  		rdev = md_import_device(dev, -1, 0);
  		if (IS_ERR(rdev)) {
  			printk(KERN_WARNING
  				"md: error, md_import_device() returned %ld\n",
  				PTR_ERR(rdev));
  			return PTR_ERR(rdev);
  		}
  		rdev->desc_nr = info->number;
  		if (info->raid_disk < mddev->raid_disks)
  			rdev->raid_disk = info->raid_disk;
  		else
  			rdev->raid_disk = -1;
  
  		if (rdev->raid_disk < mddev->raid_disks)
  			if (info->state & (1<<MD_DISK_SYNC))
  				set_bit(In_sync, &rdev->flags);
  
  		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
  			set_bit(WriteMostly, &rdev->flags);
  
  		if (!mddev->persistent) {
  			printk(KERN_INFO "md: nonpersistent superblock ...\n");
  			rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
  		} else
  			rdev->sb_start = calc_dev_sboffset(rdev);
  		rdev->sectors = rdev->sb_start;
  
  		err = bind_rdev_to_array(rdev, mddev);
  		if (err) {
  			export_rdev(rdev);
  			return err;
  		}
  	}
  
  	return 0;
  }
  
  static int hot_remove_disk(mddev_t * mddev, dev_t dev)
  {
  	char b[BDEVNAME_SIZE];
  	mdk_rdev_t *rdev;
  
  	rdev = find_rdev(mddev, dev);
  	if (!rdev)
  		return -ENXIO;
  
  	if (rdev->raid_disk >= 0)
  		goto busy;
  
  	kick_rdev_from_array(rdev);
  	md_update_sb(mddev, 1);
  	md_new_event(mddev);
  
  	return 0;
  busy:
  	printk(KERN_WARNING "md: cannot remove active disk %s from %s ...\n",
  		bdevname(rdev->bdev,b), mdname(mddev));
  	return -EBUSY;
  }
  
  static int hot_add_disk(mddev_t * mddev, dev_t dev)
  {
  	char b[BDEVNAME_SIZE];
  	int err;
  	mdk_rdev_t *rdev;
  
  	if (!mddev->pers)
  		return -ENODEV;
  
  	if (mddev->major_version != 0) {
  		printk(KERN_WARNING "%s: HOT_ADD may only be used with"
  			" version-0 superblocks.\n",
  			mdname(mddev));
  		return -EINVAL;
  	}
  	if (!mddev->pers->hot_add_disk) {
  		printk(KERN_WARNING
  			"%s: personality does not support diskops!\n",
  			mdname(mddev));
  		return -EINVAL;
  	}
  
  	rdev = md_import_device(dev, -1, 0);
  	if (IS_ERR(rdev)) {
  		printk(KERN_WARNING
  			"md: error, md_import_device() returned %ld\n",
  			PTR_ERR(rdev));
  		return -EINVAL;
  	}
  
  	if (mddev->persistent)
  		rdev->sb_start = calc_dev_sboffset(rdev);
  	else
  		rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
  
  	rdev->sectors = rdev->sb_start;
  
  	if (test_bit(Faulty, &rdev->flags)) {
  		printk(KERN_WARNING
  			"md: can not hot-add faulty %s disk to %s!\n",
  			bdevname(rdev->bdev,b), mdname(mddev));
  		err = -EINVAL;
  		goto abort_export;
  	}
  	clear_bit(In_sync, &rdev->flags);
  	rdev->desc_nr = -1;
  	rdev->saved_raid_disk = -1;
  	err = bind_rdev_to_array(rdev, mddev);
  	if (err)
  		goto abort_export;
  
  	/*
  	 * The rest should better be atomic, we can have disk failures
  	 * noticed in interrupt contexts ...
  	 */
  
  	rdev->raid_disk = -1;
  
  	md_update_sb(mddev, 1);
  
  	/*
  	 * Kick recovery, maybe this spare has to be added to the
  	 * array immediately.
  	 */
  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	md_wakeup_thread(mddev->thread);
  	md_new_event(mddev);
  	return 0;
  
  abort_export:
  	export_rdev(rdev);
  	return err;
  }
  
  static int set_bitmap_file(mddev_t *mddev, int fd)
  {
  	int err;
  
  	if (mddev->pers) {
  		if (!mddev->pers->quiesce)
  			return -EBUSY;
  		if (mddev->recovery || mddev->sync_thread)
  			return -EBUSY;
  		/* we should be able to change the bitmap.. */
  	}
  
  	if (fd >= 0) {
  		if (mddev->bitmap)
  			return -EEXIST; /* cannot add when bitmap is present */
  		mddev->bitmap_info.file = fget(fd);
  
  		if (mddev->bitmap_info.file == NULL) {
  			printk(KERN_ERR "%s: error: failed to get bitmap file\n",
  			       mdname(mddev));
  			return -EBADF;
  		}
  
  		err = deny_bitmap_write_access(mddev->bitmap_info.file);
  		if (err) {
  			printk(KERN_ERR "%s: error: bitmap file is already in use\n",
  			       mdname(mddev));
  			fput(mddev->bitmap_info.file);
  			mddev->bitmap_info.file = NULL;
  			return err;
  		}
  		mddev->bitmap_info.offset = 0; /* file overrides offset */
  	} else if (mddev->bitmap == NULL)
  		return -ENOENT; /* cannot remove what isn't there */
  	err = 0;
  	if (mddev->pers) {
  		mddev->pers->quiesce(mddev, 1);
  		if (fd >= 0) {
  			err = bitmap_create(mddev);
  			if (!err)
  				err = bitmap_load(mddev);
  		}
  		if (fd < 0 || err) {
  			bitmap_destroy(mddev);
  			fd = -1; /* make sure to put the file */
  		}
  		mddev->pers->quiesce(mddev, 0);
  	}
  	if (fd < 0) {
  		if (mddev->bitmap_info.file) {
  			restore_bitmap_write_access(mddev->bitmap_info.file);
  			fput(mddev->bitmap_info.file);
  		}
  		mddev->bitmap_info.file = NULL;
  	}
  
  	return err;
  }
  
  /*
   * set_array_info is used two different ways
   * The original usage is when creating a new array.
   * In this usage, raid_disks is > 0 and it together with
   *  level, size, not_persistent,layout,chunksize determine the
   *  shape of the array.
   *  This will always create an array with a type-0.90.0 superblock.
   * The newer usage is when assembling an array.
   *  In this case raid_disks will be 0, and the major_version field is
   *  use to determine which style super-blocks are to be found on the devices.
   *  The minor and patch _version numbers are also kept incase the
   *  super_block handler wishes to interpret them.
   */
  static int set_array_info(mddev_t * mddev, mdu_array_info_t *info)
  {
  
  	if (info->raid_disks == 0) {
  		/* just setting version number for superblock loading */
  		if (info->major_version < 0 ||
  		    info->major_version >= ARRAY_SIZE(super_types) ||
  		    super_types[info->major_version].name == NULL) {
  			/* maybe try to auto-load a module? */
  			printk(KERN_INFO
  				"md: superblock version %d not known\n",
  				info->major_version);
  			return -EINVAL;
  		}
  		mddev->major_version = info->major_version;
  		mddev->minor_version = info->minor_version;
  		mddev->patch_version = info->patch_version;
  		mddev->persistent = !info->not_persistent;
  		/* ensure mddev_put doesn't delete this now that there
  		 * is some minimal configuration.
  		 */
  		mddev->ctime         = get_seconds();
  		return 0;
  	}
  	mddev->major_version = MD_MAJOR_VERSION;
  	mddev->minor_version = MD_MINOR_VERSION;
  	mddev->patch_version = MD_PATCHLEVEL_VERSION;
  	mddev->ctime         = get_seconds();
  
  	mddev->level         = info->level;
  	mddev->clevel[0]     = 0;
  	mddev->dev_sectors   = 2 * (sector_t)info->size;
  	mddev->raid_disks    = info->raid_disks;
  	/* don't set md_minor, it is determined by which /dev/md* was
  	 * openned
  	 */
  	if (info->state & (1<<MD_SB_CLEAN))
  		mddev->recovery_cp = MaxSector;
  	else
  		mddev->recovery_cp = 0;
  	mddev->persistent    = ! info->not_persistent;
  	mddev->external	     = 0;
  
  	mddev->layout        = info->layout;
  	mddev->chunk_sectors = info->chunk_size >> 9;
  
  	mddev->max_disks     = MD_SB_DISKS;
  
  	if (mddev->persistent)
  		mddev->flags         = 0;
  	set_bit(MD_CHANGE_DEVS, &mddev->flags);
  
  	mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
  	mddev->bitmap_info.offset = 0;
  
  	mddev->reshape_position = MaxSector;
  
  	/*
  	 * Generate a 128 bit UUID
  	 */
  	get_random_bytes(mddev->uuid, 16);
  
  	mddev->new_level = mddev->level;
  	mddev->new_chunk_sectors = mddev->chunk_sectors;
  	mddev->new_layout = mddev->layout;
  	mddev->delta_disks = 0;
  
  	return 0;
  }
  
  void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors)
  {
  	WARN(!mddev_is_locked(mddev), "%s: unlocked mddev!\n", __func__);
  
  	if (mddev->external_size)
  		return;
  
  	mddev->array_sectors = array_sectors;
  }
  EXPORT_SYMBOL(md_set_array_sectors);
  
  static int update_size(mddev_t *mddev, sector_t num_sectors)
  {
  	mdk_rdev_t *rdev;
  	int rv;
  	int fit = (num_sectors == 0);
  
  	if (mddev->pers->resize == NULL)
  		return -EINVAL;
  	/* The "num_sectors" is the number of sectors of each device that
  	 * is used.  This can only make sense for arrays with redundancy.
  	 * linear and raid0 always use whatever space is available. We can only
  	 * consider changing this number if no resync or reconstruction is
  	 * happening, and if the new size is acceptable. It must fit before the
  	 * sb_start or, if that is <data_offset, it must fit before the size
  	 * of each device.  If num_sectors is zero, we find the largest size
  	 * that fits.
  	 */
  	if (mddev->sync_thread)
  		return -EBUSY;
  	if (mddev->bitmap)
  		/* Sorry, cannot grow a bitmap yet, just remove it,
  		 * grow, and re-add.
  		 */
  		return -EBUSY;
  	list_for_each_entry(rdev, &mddev->disks, same_set) {
  		sector_t avail = rdev->sectors;
  
  		if (fit && (num_sectors == 0 || num_sectors > avail))
  			num_sectors = avail;
  		if (avail < num_sectors)
  			return -ENOSPC;
  	}
  	rv = mddev->pers->resize(mddev, num_sectors);
  	if (!rv)
  		revalidate_disk(mddev->gendisk);
  	return rv;
  }
  
  static int update_raid_disks(mddev_t *mddev, int raid_disks)
  {
  	int rv;
  	/* change the number of raid disks */
  	if (mddev->pers->check_reshape == NULL)
  		return -EINVAL;
  	if (raid_disks <= 0 ||
  	    (mddev->max_disks && raid_disks >= mddev->max_disks))
  		return -EINVAL;
  	if (mddev->sync_thread || mddev->reshape_position != MaxSector)
  		return -EBUSY;
  	mddev->delta_disks = raid_disks - mddev->raid_disks;
  
  	rv = mddev->pers->check_reshape(mddev);
  	if (rv < 0)
  		mddev->delta_disks = 0;
  	return rv;
  }
  
  /*
   * update_array_info is used to change the configuration of an
   * on-line array.
   * The version, ctime,level,size,raid_disks,not_persistent, layout,chunk_size
   * fields in the info are checked against the array.
   * Any differences that cannot be handled will cause an error.
   * Normally, only one change can be managed at a time.
   */
  static int update_array_info(mddev_t *mddev, mdu_array_info_t *info)
  {
  	int rv = 0;
  	int cnt = 0;
  	int state = 0;
  
  	/* calculate expected state,ignoring low bits */
  	if (mddev->bitmap && mddev->bitmap_info.offset)
  		state |= (1 << MD_SB_BITMAP_PRESENT);
  
  	if (mddev->major_version != info->major_version ||
  	    mddev->minor_version != info->minor_version ||
  /*	    mddev->patch_version != info->patch_version || */
  	    mddev->ctime         != info->ctime         ||
  	    mddev->level         != info->level         ||
  /*	    mddev->layout        != info->layout        || */
  	    !mddev->persistent	 != info->not_persistent||
  	    mddev->chunk_sectors != info->chunk_size >> 9 ||
  	    /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
  	    ((state^info->state) & 0xfffffe00)
  		)
  		return -EINVAL;
  	/* Check there is only one change */
  	if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
  		cnt++;
  	if (mddev->raid_disks != info->raid_disks)
  		cnt++;
  	if (mddev->layout != info->layout)
  		cnt++;
  	if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT))
  		cnt++;
  	if (cnt == 0)
  		return 0;
  	if (cnt > 1)
  		return -EINVAL;
  
  	if (mddev->layout != info->layout) {
  		/* Change layout
  		 * we don't need to do anything at the md level, the
  		 * personality will take care of it all.
  		 */
  		if (mddev->pers->check_reshape == NULL)
  			return -EINVAL;
  		else {
  			mddev->new_layout = info->layout;
  			rv = mddev->pers->check_reshape(mddev);
  			if (rv)
  				mddev->new_layout = mddev->layout;
  			return rv;
  		}
  	}
  	if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
  		rv = update_size(mddev, (sector_t)info->size * 2);
  
  	if (mddev->raid_disks    != info->raid_disks)
  		rv = update_raid_disks(mddev, info->raid_disks);
  
  	if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
  		if (mddev->pers->quiesce == NULL)
  			return -EINVAL;
  		if (mddev->recovery || mddev->sync_thread)
  			return -EBUSY;
  		if (info->state & (1<<MD_SB_BITMAP_PRESENT)) {
  			/* add the bitmap */
  			if (mddev->bitmap)
  				return -EEXIST;
  			if (mddev->bitmap_info.default_offset == 0)
  				return -EINVAL;
  			mddev->bitmap_info.offset =
  				mddev->bitmap_info.default_offset;
  			mddev->pers->quiesce(mddev, 1);
  			rv = bitmap_create(mddev);
  			if (!rv)
  				rv = bitmap_load(mddev);
  			if (rv)
  				bitmap_destroy(mddev);
  			mddev->pers->quiesce(mddev, 0);
  		} else {
  			/* remove the bitmap */
  			if (!mddev->bitmap)
  				return -ENOENT;
  			if (mddev->bitmap->file)
  				return -EINVAL;
  			mddev->pers->quiesce(mddev, 1);
  			bitmap_destroy(mddev);
  			mddev->pers->quiesce(mddev, 0);
  			mddev->bitmap_info.offset = 0;
  		}
  	}
  	md_update_sb(mddev, 1);
  	return rv;
  }
  
  static int set_disk_faulty(mddev_t *mddev, dev_t dev)
  {
  	mdk_rdev_t *rdev;
  
  	if (mddev->pers == NULL)
  		return -ENODEV;
  
  	rdev = find_rdev(mddev, dev);
  	if (!rdev)
  		return -ENODEV;
  
  	md_error(mddev, rdev);
  	return 0;
  }
  
  /*
   * We have a problem here : there is no easy way to give a CHS
   * virtual geometry. We currently pretend that we have a 2 heads
   * 4 sectors (with a BIG number of cylinders...). This drives
   * dosfs just mad... ;-)
   */
  static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo)
  {
  	mddev_t *mddev = bdev->bd_disk->private_data;
  
  	geo->heads = 2;
  	geo->sectors = 4;
  	geo->cylinders = mddev->array_sectors / 8;
  	return 0;
  }
  
  static int md_ioctl(struct block_device *bdev, fmode_t mode,
  			unsigned int cmd, unsigned long arg)
  {
  	int err = 0;
  	void __user *argp = (void __user *)arg;
  	mddev_t *mddev = NULL;
  	int ro;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;
  
  	/*
  	 * Commands dealing with the RAID driver but not any
  	 * particular array:
  	 */
  	switch (cmd)
  	{
  		case RAID_VERSION:
  			err = get_version(argp);
  			goto done;
  
  		case PRINT_RAID_DEBUG:
  			err = 0;
  			md_print_devices();
  			goto done;
  
  #ifndef MODULE
  		case RAID_AUTORUN:
  			err = 0;
  			autostart_arrays(arg);
  			goto done;
  #endif
  		default:;
  	}
  
  	/*
  	 * Commands creating/starting a new array:
  	 */
  
  	mddev = bdev->bd_disk->private_data;
  
  	if (!mddev) {
  		BUG();
  		goto abort;
  	}
  
  	err = mddev_lock(mddev);
  	if (err) {
  		printk(KERN_INFO
  			"md: ioctl lock interrupted, reason %d, cmd %d\n",
  			err, cmd);
  		goto abort;
  	}
  
  	switch (cmd)
  	{
  		case SET_ARRAY_INFO:
  			{
  				mdu_array_info_t info;
  				if (!arg)
  					memset(&info, 0, sizeof(info));
  				else if (copy_from_user(&info, argp, sizeof(info))) {
  					err = -EFAULT;
  					goto abort_unlock;
  				}
  				if (mddev->pers) {
  					err = update_array_info(mddev, &info);
  					if (err) {
  						printk(KERN_WARNING "md: couldn't update"
  						       " array info. %d\n", err);
  						goto abort_unlock;
  					}
  					goto done_unlock;
  				}
  				if (!list_empty(&mddev->disks)) {
  					printk(KERN_WARNING
  					       "md: array %s already has disks!\n",
  					       mdname(mddev));
  					err = -EBUSY;
  					goto abort_unlock;
  				}
  				if (mddev->raid_disks) {
  					printk(KERN_WARNING
  					       "md: array %s already initialised!\n",
  					       mdname(mddev));
  					err = -EBUSY;
  					goto abort_unlock;
  				}
  				err = set_array_info(mddev, &info);
  				if (err) {
  					printk(KERN_WARNING "md: couldn't set"
  					       " array info. %d\n", err);
  					goto abort_unlock;
  				}
  			}
  			goto done_unlock;
  
  		default:;
  	}
  
  	/*
  	 * Commands querying/configuring an existing array:
  	 */
  	/* if we are not initialised yet, only ADD_NEW_DISK, STOP_ARRAY,
  	 * RUN_ARRAY, and GET_ and SET_BITMAP_FILE are allowed */
  	if ((!mddev->raid_disks && !mddev->external)
  	    && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY
  	    && cmd != RUN_ARRAY && cmd != SET_BITMAP_FILE
  	    && cmd != GET_BITMAP_FILE) {
  		err = -ENODEV;
  		goto abort_unlock;
  	}
  
  	/*
  	 * Commands even a read-only array can execute:
  	 */
  	switch (cmd)
  	{
  		case GET_ARRAY_INFO:
  			err = get_array_info(mddev, argp);
  			goto done_unlock;
  
  		case GET_BITMAP_FILE:
  			err = get_bitmap_file(mddev, argp);
  			goto done_unlock;
  
  		case GET_DISK_INFO:
  			err = get_disk_info(mddev, argp);
  			goto done_unlock;
  
  		case RESTART_ARRAY_RW:
  			err = restart_array(mddev);
  			goto done_unlock;
  
  		case STOP_ARRAY:
  			err = do_md_stop(mddev, 0, 1);
  			goto done_unlock;
  
  		case STOP_ARRAY_RO:
  			err = md_set_readonly(mddev, 1);
  			goto done_unlock;
  
  		case BLKROSET:
  			if (get_user(ro, (int __user *)(arg))) {
  				err = -EFAULT;
  				goto done_unlock;
  			}
  			err = -EINVAL;
  
  			/* if the bdev is going readonly the value of mddev->ro
  			 * does not matter, no writes are coming
  			 */
  			if (ro)
  				goto done_unlock;
  
  			/* are we are already prepared for writes? */
  			if (mddev->ro != 1)
  				goto done_unlock;
  
  			/* transitioning to readauto need only happen for
  			 * arrays that call md_write_start
  			 */
  			if (mddev->pers) {
  				err = restart_array(mddev);
  				if (err == 0) {
  					mddev->ro = 2;
  					set_disk_ro(mddev->gendisk, 0);
  				}
  			}
  			goto done_unlock;
  	}
  
  	/*
  	 * The remaining ioctls are changing the state of the
  	 * superblock, so we do not allow them on read-only arrays.
  	 * However non-MD ioctls (e.g. get-size) will still come through
  	 * here and hit the 'default' below, so only disallow
  	 * 'md' ioctls, and switch to rw mode if started auto-readonly.
  	 */
  	if (_IOC_TYPE(cmd) == MD_MAJOR && mddev->ro && mddev->pers) {
  		if (mddev->ro == 2) {
  			mddev->ro = 0;
  			sysfs_notify_dirent_safe(mddev->sysfs_state);
  			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  			md_wakeup_thread(mddev->thread);
  		} else {
  			err = -EROFS;
  			goto abort_unlock;
  		}
  	}
  
  	switch (cmd)
  	{
  		case ADD_NEW_DISK:
  		{
  			mdu_disk_info_t info;
  			if (copy_from_user(&info, argp, sizeof(info)))
  				err = -EFAULT;
  			else
  				err = add_new_disk(mddev, &info);
  			goto done_unlock;
  		}
  
  		case HOT_REMOVE_DISK:
  			err = hot_remove_disk(mddev, new_decode_dev(arg));
  			goto done_unlock;
  
  		case HOT_ADD_DISK:
  			err = hot_add_disk(mddev, new_decode_dev(arg));
  			goto done_unlock;
  
  		case SET_DISK_FAULTY:
  			err = set_disk_faulty(mddev, new_decode_dev(arg));
  			goto done_unlock;
  
  		case RUN_ARRAY:
  			err = do_md_run(mddev);
  			goto done_unlock;
  
  		case SET_BITMAP_FILE:
  			err = set_bitmap_file(mddev, (int)arg);
  			goto done_unlock;
  
  		default:
  			err = -EINVAL;
  			goto abort_unlock;
  	}
  
  done_unlock:
  abort_unlock:
  	if (mddev->hold_active == UNTIL_IOCTL &&
  	    err != -EINVAL)
  		mddev->hold_active = 0;
  	mddev_unlock(mddev);
  
  	return err;
  done:
  	if (err)
  		MD_BUG();
  abort:
  	return err;
  }
  #ifdef CONFIG_COMPAT
  static int md_compat_ioctl(struct block_device *bdev, fmode_t mode,
  		    unsigned int cmd, unsigned long arg)
  {
  	switch (cmd) {
  	case HOT_REMOVE_DISK:
  	case HOT_ADD_DISK:
  	case SET_DISK_FAULTY:
  	case SET_BITMAP_FILE:
  		/* These take in integer arg, do not convert */
  		break;
  	default:
  		arg = (unsigned long)compat_ptr(arg);
  		break;
  	}
  
  	return md_ioctl(bdev, mode, cmd, arg);
  }
  #endif /* CONFIG_COMPAT */
  
  static int md_open(struct block_device *bdev, fmode_t mode)
  {
  	/*
  	 * Succeed if we can lock the mddev, which confirms that
  	 * it isn't being stopped right now.
  	 */
  	mddev_t *mddev = mddev_find(bdev->bd_dev);
  	int err;
  
  	if (mddev->gendisk != bdev->bd_disk) {
  		/* we are racing with mddev_put which is discarding this
  		 * bd_disk.
  		 */
  		mddev_put(mddev);
  		/* Wait until bdev->bd_disk is definitely gone */
  		flush_workqueue(md_misc_wq);
  		/* Then retry the open from the top */
  		return -ERESTARTSYS;
  	}
  	BUG_ON(mddev != bdev->bd_disk->private_data);
  
  	if ((err = mutex_lock_interruptible(&mddev->open_mutex)))
  		goto out;
  
  	err = 0;
  	atomic_inc(&mddev->openers);
  	mutex_unlock(&mddev->open_mutex);
  
  	check_disk_change(bdev);
   out:
  	return err;
  }
  
  static int md_release(struct gendisk *disk, fmode_t mode)
  {
   	mddev_t *mddev = disk->private_data;
  
  	BUG_ON(!mddev);
  	atomic_dec(&mddev->openers);
  	mddev_put(mddev);
  
  	return 0;
  }
  
  static int md_media_changed(struct gendisk *disk)
  {
  	mddev_t *mddev = disk->private_data;
  
  	return mddev->changed;
  }
  
  static int md_revalidate(struct gendisk *disk)
  {
  	mddev_t *mddev = disk->private_data;
  
  	mddev->changed = 0;
  	return 0;
  }
  static const struct block_device_operations md_fops =
  {
  	.owner		= THIS_MODULE,
  	.open		= md_open,
  	.release	= md_release,
  	.ioctl		= md_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= md_compat_ioctl,
  #endif
  	.getgeo		= md_getgeo,
  	.media_changed  = md_media_changed,
  	.revalidate_disk= md_revalidate,
  };
  
  static int md_thread(void * arg)
  {
  	mdk_thread_t *thread = arg;
  
  	/*
  	 * md_thread is a 'system-thread', it's priority should be very
  	 * high. We avoid resource deadlocks individually in each
  	 * raid personality. (RAID5 does preallocation) We also use RR and
  	 * the very same RT priority as kswapd, thus we will never get
  	 * into a priority inversion deadlock.
  	 *
  	 * we definitely have to have equal or higher priority than
  	 * bdflush, otherwise bdflush will deadlock if there are too
  	 * many dirty RAID5 blocks.
  	 */
  
  	allow_signal(SIGKILL);
  	while (!kthread_should_stop()) {
  
  		/* We need to wait INTERRUPTIBLE so that
  		 * we don't add to the load-average.
  		 * That means we need to be sure no signals are
  		 * pending
  		 */
  		if (signal_pending(current))
  			flush_signals(current);
  
  		wait_event_interruptible_timeout
  			(thread->wqueue,
  			 test_bit(THREAD_WAKEUP, &thread->flags)
  			 || kthread_should_stop(),
  			 thread->timeout);
  
  		clear_bit(THREAD_WAKEUP, &thread->flags);
  		if (!kthread_should_stop())
  			thread->run(thread->mddev);
  	}
  
  	return 0;
  }
  
  void md_wakeup_thread(mdk_thread_t *thread)
  {
  	if (thread) {
  		dprintk("md: waking up MD thread %s.\n", thread->tsk->comm);
  		set_bit(THREAD_WAKEUP, &thread->flags);
  		wake_up(&thread->wqueue);
  	}
  }
  
  mdk_thread_t *md_register_thread(void (*run) (mddev_t *), mddev_t *mddev,
  				 const char *name)
  {
  	mdk_thread_t *thread;
  
  	thread = kzalloc(sizeof(mdk_thread_t), GFP_KERNEL);
  	if (!thread)
  		return NULL;
  
  	init_waitqueue_head(&thread->wqueue);
  
  	thread->run = run;
  	thread->mddev = mddev;
  	thread->timeout = MAX_SCHEDULE_TIMEOUT;
  	thread->tsk = kthread_run(md_thread, thread,
  				  "%s_%s",
  				  mdname(thread->mddev),
  				  name ?: mddev->pers->name);
  	if (IS_ERR(thread->tsk)) {
  		kfree(thread);
  		return NULL;
  	}
  	return thread;
  }
  
  void md_unregister_thread(mdk_thread_t **threadp)
  {
  	mdk_thread_t *thread = *threadp;
  	if (!thread)
  		return;
  	dprintk("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
  	/* Locking ensures that mddev_unlock does not wake_up a
  	 * non-existent thread
  	 */
  	spin_lock(&pers_lock);
  	*threadp = NULL;
  	spin_unlock(&pers_lock);
  
  	kthread_stop(thread->tsk);
  	kfree(thread);
  }
  
  void md_error(mddev_t *mddev, mdk_rdev_t *rdev)
  {
  	if (!mddev) {
  		MD_BUG();
  		return;
  	}
  
  	if (!rdev || test_bit(Faulty, &rdev->flags))
  		return;
  
  	if (mddev->external)
  		set_bit(Blocked, &rdev->flags);
  /*
  	dprintk("md_error dev:%s, rdev:(%d:%d), (caller: %p,%p,%p,%p).\n",
  		mdname(mddev),
  		MAJOR(rdev->bdev->bd_dev), MINOR(rdev->bdev->bd_dev),
  		__builtin_return_address(0),__builtin_return_address(1),
  		__builtin_return_address(2),__builtin_return_address(3));
  */
  	if (!mddev->pers)
  		return;
  	if (!mddev->pers->error_handler)
  		return;
  	mddev->pers->error_handler(mddev,rdev);
  	if (mddev->degraded)
  		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
  	sysfs_notify_dirent_safe(rdev->sysfs_state);
  	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	md_wakeup_thread(mddev->thread);
  	if (mddev->event_work.func)
  		queue_work(md_misc_wq, &mddev->event_work);
  	md_new_event_inintr(mddev);
  }
  
  /* seq_file implementation /proc/mdstat */
  
  static void status_unused(struct seq_file *seq)
  {
  	int i = 0;
  	mdk_rdev_t *rdev;
  
  	seq_printf(seq, "unused devices: ");
  
  	list_for_each_entry(rdev, &pending_raid_disks, same_set) {
  		char b[BDEVNAME_SIZE];
  		i++;
  		seq_printf(seq, "%s ",
  			      bdevname(rdev->bdev,b));
  	}
  	if (!i)
  		seq_printf(seq, "<none>");
  
  	seq_printf(seq, "\n");
  }
  
  static void status_resync(struct seq_file *seq, mddev_t * mddev)
  {
  	sector_t max_sectors, resync, res;
  	unsigned long dt, db;
  	sector_t rt;
  	int scale;
  	unsigned int per_milli;
  
  	resync = mddev->curr_resync - atomic_read(&mddev->recovery_active);
  
  	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
  		max_sectors = mddev->resync_max_sectors;
  	else
  		max_sectors = mddev->dev_sectors;
  
  	/*
  	 * Should not happen.
  	 */
  	if (!max_sectors) {
  		MD_BUG();
  		return;
  	}
  	/* Pick 'scale' such that (resync>>scale)*1000 will fit
  	 * in a sector_t, and (max_sectors>>scale) will fit in a
  	 * u32, as those are the requirements for sector_div.
  	 * Thus 'scale' must be at least 10
  	 */
  	scale = 10;
  	if (sizeof(sector_t) > sizeof(unsigned long)) {
  		while ( max_sectors/2 > (1ULL<<(scale+32)))
  			scale++;
  	}
  	res = (resync>>scale)*1000;
  	sector_div(res, (u32)((max_sectors>>scale)+1));
  
  	per_milli = res;
  	{
  		int i, x = per_milli/50, y = 20-x;
  		seq_printf(seq, "[");
  		for (i = 0; i < x; i++)
  			seq_printf(seq, "=");
  		seq_printf(seq, ">");
  		for (i = 0; i < y; i++)
  			seq_printf(seq, ".");
  		seq_printf(seq, "] ");
  	}
  	seq_printf(seq, " %s =%3u.%u%% (%llu/%llu)",
  		   (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)?
  		    "reshape" :
  		    (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)?
  		     "check" :
  		     (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ?
  		      "resync" : "recovery"))),
  		   per_milli/10, per_milli % 10,
  		   (unsigned long long) resync/2,
  		   (unsigned long long) max_sectors/2);
  
  	/*
  	 * dt: time from mark until now
  	 * db: blocks written from mark until now
  	 * rt: remaining time
  	 *
  	 * rt is a sector_t, so could be 32bit or 64bit.
  	 * So we divide before multiply in case it is 32bit and close
  	 * to the limit.
  	 * We scale the divisor (db) by 32 to avoid losing precision
  	 * near the end of resync when the number of remaining sectors
  	 * is close to 'db'.
  	 * We then divide rt by 32 after multiplying by db to compensate.
  	 * The '+1' avoids division by zero if db is very small.
  	 */
  	dt = ((jiffies - mddev->resync_mark) / HZ);
  	if (!dt) dt++;
  	db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active))
  		- mddev->resync_mark_cnt;
  
  	rt = max_sectors - resync;    /* number of remaining sectors */
  	sector_div(rt, db/32+1);
  	rt *= dt;
  	rt >>= 5;
  
  	seq_printf(seq, " finish=%lu.%lumin", (unsigned long)rt / 60,
  		   ((unsigned long)rt % 60)/6);
  
  	seq_printf(seq, " speed=%ldK/sec", db/2/dt);
  }
  
  static void *md_seq_start(struct seq_file *seq, loff_t *pos)
  {
  	struct list_head *tmp;
  	loff_t l = *pos;
  	mddev_t *mddev;
  
  	if (l >= 0x10000)
  		return NULL;
  	if (!l--)
  		/* header */
  		return (void*)1;
  
  	spin_lock(&all_mddevs_lock);
  	list_for_each(tmp,&all_mddevs)
  		if (!l--) {
  			mddev = list_entry(tmp, mddev_t, all_mddevs);
  			mddev_get(mddev);
  			spin_unlock(&all_mddevs_lock);
  			return mddev;
  		}
  	spin_unlock(&all_mddevs_lock);
  	if (!l--)
  		return (void*)2;/* tail */
  	return NULL;
  }
  
  static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {
  	struct list_head *tmp;
  	mddev_t *next_mddev, *mddev = v;
  
  	++*pos;
  	if (v == (void*)2)
  		return NULL;
  
  	spin_lock(&all_mddevs_lock);
  	if (v == (void*)1)
  		tmp = all_mddevs.next;
  	else
  		tmp = mddev->all_mddevs.next;
  	if (tmp != &all_mddevs)
  		next_mddev = mddev_get(list_entry(tmp,mddev_t,all_mddevs));
  	else {
  		next_mddev = (void*)2;
  		*pos = 0x10000;
  	}
  	spin_unlock(&all_mddevs_lock);
  
  	if (v != (void*)1)
  		mddev_put(mddev);
  	return next_mddev;
  
  }
  
  static void md_seq_stop(struct seq_file *seq, void *v)
  {
  	mddev_t *mddev = v;
  
  	if (mddev && v != (void*)1 && v != (void*)2)
  		mddev_put(mddev);
  }
  
  struct mdstat_info {
  	int event;
  };
  
  static int md_seq_show(struct seq_file *seq, void *v)
  {
  	mddev_t *mddev = v;
  	sector_t sectors;
  	mdk_rdev_t *rdev;
  	struct mdstat_info *mi = seq->private;
  	struct bitmap *bitmap;
  
  	if (v == (void*)1) {
  		struct mdk_personality *pers;
  		seq_printf(seq, "Personalities : ");
  		spin_lock(&pers_lock);
  		list_for_each_entry(pers, &pers_list, list)
  			seq_printf(seq, "[%s] ", pers->name);
  
  		spin_unlock(&pers_lock);
  		seq_printf(seq, "\n");
  		mi->event = atomic_read(&md_event_count);
  		return 0;
  	}
  	if (v == (void*)2) {
  		status_unused(seq);
  		return 0;
  	}
  
  	if (mddev_lock(mddev) < 0)
  		return -EINTR;
  
  	if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
  		seq_printf(seq, "%s : %sactive", mdname(mddev),
  						mddev->pers ? "" : "in");
  		if (mddev->pers) {
  			if (mddev->ro==1)
  				seq_printf(seq, " (read-only)");
  			if (mddev->ro==2)
  				seq_printf(seq, " (auto-read-only)");
  			seq_printf(seq, " %s", mddev->pers->name);
  		}
  
  		sectors = 0;
  		list_for_each_entry(rdev, &mddev->disks, same_set) {
  			char b[BDEVNAME_SIZE];
  			seq_printf(seq, " %s[%d]",
  				bdevname(rdev->bdev,b), rdev->desc_nr);
  			if (test_bit(WriteMostly, &rdev->flags))
  				seq_printf(seq, "(W)");
  			if (test_bit(Faulty, &rdev->flags)) {
  				seq_printf(seq, "(F)");
  				continue;
  			} else if (rdev->raid_disk < 0)
  				seq_printf(seq, "(S)"); /* spare */
  			sectors += rdev->sectors;
  		}
  
  		if (!list_empty(&mddev->disks)) {
  			if (mddev->pers)
  				seq_printf(seq, "\n      %llu blocks",
  					   (unsigned long long)
  					   mddev->array_sectors / 2);
  			else
  				seq_printf(seq, "\n      %llu blocks",
  					   (unsigned long long)sectors / 2);
  		}
  		if (mddev->persistent) {
  			if (mddev->major_version != 0 ||
  			    mddev->minor_version != 90) {
  				seq_printf(seq," super %d.%d",
  					   mddev->major_version,
  					   mddev->minor_version);
  			}
  		} else if (mddev->external)
  			seq_printf(seq, " super external:%s",
  				   mddev->metadata_type);
  		else
  			seq_printf(seq, " super non-persistent");
  
  		if (mddev->pers) {
  			mddev->pers->status(seq, mddev);
  	 		seq_printf(seq, "\n      ");
  			if (mddev->pers->sync_request) {
  				if (mddev->curr_resync > 2) {
  					status_resync(seq, mddev);
  					seq_printf(seq, "\n      ");
  				} else if (mddev->curr_resync == 1 || mddev->curr_resync == 2)
  					seq_printf(seq, "\tresync=DELAYED\n      ");
  				else if (mddev->recovery_cp < MaxSector)
  					seq_printf(seq, "\tresync=PENDING\n      ");
  			}
  		} else
  			seq_printf(seq, "\n       ");
  
  		if ((bitmap = mddev->bitmap)) {
  			unsigned long chunk_kb;
  			unsigned long flags;
  			spin_lock_irqsave(&bitmap->lock, flags);
  			chunk_kb = mddev->bitmap_info.chunksize >> 10;
  			seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], "
  				"%lu%s chunk",
  				bitmap->pages - bitmap->missing_pages,
  				bitmap->pages,
  				(bitmap->pages - bitmap->missing_pages)
  					<< (PAGE_SHIFT - 10),
  				chunk_kb ? chunk_kb : mddev->bitmap_info.chunksize,
  				chunk_kb ? "KB" : "B");
  			if (bitmap->file) {
  				seq_printf(seq, ", file: ");
  				seq_path(seq, &bitmap->file->f_path, " \t\n");
  			}
  
  			seq_printf(seq, "\n");
  			spin_unlock_irqrestore(&bitmap->lock, flags);
  		}
  
  		seq_printf(seq, "\n");
  	}
  	mddev_unlock(mddev);
  
  	return 0;
  }
  
  static const struct seq_operations md_seq_ops = {
  	.start  = md_seq_start,
  	.next   = md_seq_next,
  	.stop   = md_seq_stop,
  	.show   = md_seq_show,
  };
  
  static int md_seq_open(struct inode *inode, struct file *file)
  {
  	int error;
  	struct mdstat_info *mi = kmalloc(sizeof(*mi), GFP_KERNEL);
  	if (mi == NULL)
  		return -ENOMEM;
  
  	error = seq_open(file, &md_seq_ops);
  	if (error)
  		kfree(mi);
  	else {
  		struct seq_file *p = file->private_data;
  		p->private = mi;
  		mi->event = atomic_read(&md_event_count);
  	}
  	return error;
  }
  
  static unsigned int mdstat_poll(struct file *filp, poll_table *wait)
  {
  	struct seq_file *m = filp->private_data;
  	struct mdstat_info *mi = m->private;
  	int mask;
  
  	poll_wait(filp, &md_event_waiters, wait);
  
  	/* always allow read */
  	mask = POLLIN | POLLRDNORM;
  
  	if (mi->event != atomic_read(&md_event_count))
  		mask |= POLLERR | POLLPRI;
  	return mask;
  }
  
  static const struct file_operations md_seq_fops = {
  	.owner		= THIS_MODULE,
  	.open           = md_seq_open,
  	.read           = seq_read,
  	.llseek         = seq_lseek,
  	.release	= seq_release_private,
  	.poll		= mdstat_poll,
  };
  
  int register_md_personality(struct mdk_personality *p)
  {
  	spin_lock(&pers_lock);
  	list_add_tail(&p->list, &pers_list);
  	printk(KERN_INFO "md: %s personality registered for level %d\n", p->name, p->level);
  	spin_unlock(&pers_lock);
  	return 0;
  }
  
  int unregister_md_personality(struct mdk_personality *p)
  {
  	printk(KERN_INFO "md: %s personality unregistered\n", p->name);
  	spin_lock(&pers_lock);
  	list_del_init(&p->list);
  	spin_unlock(&pers_lock);
  	return 0;
  }
  
  static int is_mddev_idle(mddev_t *mddev, int init)
  {
  	mdk_rdev_t * rdev;
  	int idle;
  	int curr_events;
  
  	idle = 1;
  	rcu_read_lock();
  	rdev_for_each_rcu(rdev, mddev) {
  		struct gendisk *disk = rdev->bdev->bd_contains->bd_disk;
  		curr_events = (int)part_stat_read(&disk->part0, sectors[0]) +
  			      (int)part_stat_read(&disk->part0, sectors[1]) -
  			      atomic_read(&disk->sync_io);
  		/* sync IO will cause sync_io to increase before the disk_stats
  		 * as sync_io is counted when a request starts, and
  		 * disk_stats is counted when it completes.
  		 * So resync activity will cause curr_events to be smaller than
  		 * when there was no such activity.
  		 * non-sync IO will cause disk_stat to increase without
  		 * increasing sync_io so curr_events will (eventually)
  		 * be larger than it was before.  Once it becomes
  		 * substantially larger, the test below will cause
  		 * the array to appear non-idle, and resync will slow
  		 * down.
  		 * If there is a lot of outstanding resync activity when
  		 * we set last_event to curr_events, then all that activity
  		 * completing might cause the array to appear non-idle
  		 * and resync will be slowed down even though there might
  		 * not have been non-resync activity.  This will only
  		 * happen once though.  'last_events' will soon reflect
  		 * the state where there is little or no outstanding
  		 * resync requests, and further resync activity will
  		 * always make curr_events less than last_events.
  		 *
  		 */
  		if (init || curr_events - rdev->last_events > 64) {
  			rdev->last_events = curr_events;
  			idle = 0;
  		}
  	}
  	rcu_read_unlock();
  	return idle;
  }
  
  void md_done_sync(mddev_t *mddev, int blocks, int ok)
  {
  	/* another "blocks" (512byte) blocks have been synced */
  	atomic_sub(blocks, &mddev->recovery_active);
  	wake_up(&mddev->recovery_wait);
  	if (!ok) {
  		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
  		md_wakeup_thread(mddev->thread);
  		// stop recovery, signal do_sync ....
  	}
  }
  
  /* md_write_start(mddev, bi)
   * If we need to update some array metadata (e.g. 'active' flag
   * in superblock) before writing, schedule a superblock update
   * and wait for it to complete.
   */
  void md_write_start(mddev_t *mddev, struct bio *bi)
  {
  	int did_change = 0;
  	if (bio_data_dir(bi) != WRITE)
  		return;
  
  	BUG_ON(mddev->ro == 1);
  	if (mddev->ro == 2) {
  		/* need to switch to read/write */
  		mddev->ro = 0;
  		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  		md_wakeup_thread(mddev->thread);
  		md_wakeup_thread(mddev->sync_thread);
  		did_change = 1;
  	}
  	atomic_inc(&mddev->writes_pending);
  	if (mddev->safemode == 1)
  		mddev->safemode = 0;
  	if (mddev->in_sync) {
  		spin_lock_irq(&mddev->write_lock);
  		if (mddev->in_sync) {
  			mddev->in_sync = 0;
  			set_bit(MD_CHANGE_CLEAN, &mddev->flags);
  			set_bit(MD_CHANGE_PENDING, &mddev->flags);
  			md_wakeup_thread(mddev->thread);
  			did_change = 1;
  		}
  		spin_unlock_irq(&mddev->write_lock);
  	}
  	if (did_change)
  		sysfs_notify_dirent_safe(mddev->sysfs_state);
  	wait_event(mddev->sb_wait,
  		   !test_bit(MD_CHANGE_PENDING, &mddev->flags));
  }
  
  void md_write_end(mddev_t *mddev)
  {
  	if (atomic_dec_and_test(&mddev->writes_pending)) {
  		if (mddev->safemode == 2)
  			md_wakeup_thread(mddev->thread);
  		else if (mddev->safemode_delay)
  			mod_timer(&mddev->safemode_timer, jiffies + mddev->safemode_delay);
  	}
  }
  
  /* md_allow_write(mddev)
   * Calling this ensures that the array is marked 'active' so that writes
   * may proceed without blocking.  It is important to call this before
   * attempting a GFP_KERNEL allocation while holding the mddev lock.
   * Must be called with mddev_lock held.
   *
   * In the ->external case MD_CHANGE_CLEAN can not be cleared until mddev->lock
   * is dropped, so return -EAGAIN after notifying userspace.
   */
  int md_allow_write(mddev_t *mddev)
  {
  	if (!mddev->pers)
  		return 0;
  	if (mddev->ro)
  		return 0;
  	if (!mddev->pers->sync_request)
  		return 0;
  
  	spin_lock_irq(&mddev->write_lock);
  	if (mddev->in_sync) {
  		mddev->in_sync = 0;
  		set_bit(MD_CHANGE_CLEAN, &mddev->flags);
  		set_bit(MD_CHANGE_PENDING, &mddev->flags);
  		if (mddev->safemode_delay &&
  		    mddev->safemode == 0)
  			mddev->safemode = 1;
  		spin_unlock_irq(&mddev->write_lock);
  		md_update_sb(mddev, 0);
  		sysfs_notify_dirent_safe(mddev->sysfs_state);
  	} else
  		spin_unlock_irq(&mddev->write_lock);
  
  	if (test_bit(MD_CHANGE_PENDING, &mddev->flags))
  		return -EAGAIN;
  	else
  		return 0;
  }
  EXPORT_SYMBOL_GPL(md_allow_write);
  
  #define SYNC_MARKS	10
  #define	SYNC_MARK_STEP	(3*HZ)
  void md_do_sync(mddev_t *mddev)
  {
  	mddev_t *mddev2;
  	unsigned int currspeed = 0,
  		 window;
  	sector_t max_sectors,j, io_sectors;
  	unsigned long mark[SYNC_MARKS];
  	sector_t mark_cnt[SYNC_MARKS];
  	int last_mark,m;
  	struct list_head *tmp;
  	sector_t last_check;
  	int skipped = 0;
  	mdk_rdev_t *rdev;
  	char *desc;
  
  	/* just incase thread restarts... */
  	if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
  		return;
  	if (mddev->ro) /* never try to sync a read-only array */
  		return;
  
  	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
  		if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
  			desc = "data-check";
  		else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
  			desc = "requested-resync";
  		else
  			desc = "resync";
  	} else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
  		desc = "reshape";
  	else
  		desc = "recovery";
  
  	/* we overload curr_resync somewhat here.
  	 * 0 == not engaged in resync at all
  	 * 2 == checking that there is no conflict with another sync
  	 * 1 == like 2, but have yielded to allow conflicting resync to
  	 *		commense
  	 * other == active in resync - this many blocks
  	 *
  	 * Before starting a resync we must have set curr_resync to
  	 * 2, and then checked that every "conflicting" array has curr_resync
  	 * less than ours.  When we find one that is the same or higher
  	 * we wait on resync_wait.  To avoid deadlock, we reduce curr_resync
  	 * to 1 if we choose to yield (based arbitrarily on address of mddev structure).
  	 * This will mean we have to start checking from the beginning again.
  	 *
  	 */
  
  	do {
  		mddev->curr_resync = 2;
  
  	try_again:
  		if (kthread_should_stop())
  			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
  
  		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
  			goto skip;
  		for_each_mddev(mddev2, tmp) {
  			if (mddev2 == mddev)
  				continue;
  			if (!mddev->parallel_resync
  			&&  mddev2->curr_resync
  			&&  match_mddev_units(mddev, mddev2)) {
  				DEFINE_WAIT(wq);
  				if (mddev < mddev2 && mddev->curr_resync == 2) {
  					/* arbitrarily yield */
  					mddev->curr_resync = 1;
  					wake_up(&resync_wait);
  				}
  				if (mddev > mddev2 && mddev->curr_resync == 1)
  					/* no need to wait here, we can wait the next
  					 * time 'round when curr_resync == 2
  					 */
  					continue;
  				/* We need to wait 'interruptible' so as not to
  				 * contribute to the load average, and not to
  				 * be caught by 'softlockup'
  				 */
  				prepare_to_wait(&resync_wait, &wq, TASK_INTERRUPTIBLE);
  				if (!kthread_should_stop() &&
  				    mddev2->curr_resync >= mddev->curr_resync) {
  					printk(KERN_INFO "md: delaying %s of %s"
  					       " until %s has finished (they"
  					       " share one or more physical units)\n",
  					       desc, mdname(mddev), mdname(mddev2));
  					mddev_put(mddev2);
  					if (signal_pending(current))
  						flush_signals(current);
  					schedule();
  					finish_wait(&resync_wait, &wq);
  					goto try_again;
  				}
  				finish_wait(&resync_wait, &wq);
  			}
  		}
  	} while (mddev->curr_resync < 2);
  
  	j = 0;
  	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
  		/* resync follows the size requested by the personality,
  		 * which defaults to physical size, but can be virtual size
  		 */
  		max_sectors = mddev->resync_max_sectors;
  		mddev->resync_mismatches = 0;
  		/* we don't use the checkpoint if there's a bitmap */
  		if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
  			j = mddev->resync_min;
  		else if (!mddev->bitmap)
  			j = mddev->recovery_cp;
  
  	} else if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
  		max_sectors = mddev->dev_sectors;
  	else {
  		/* recovery follows the physical size of devices */
  		max_sectors = mddev->dev_sectors;
  		j = MaxSector;
  		rcu_read_lock();
  		list_for_each_entry_rcu(rdev, &mddev->disks, same_set)
  			if (rdev->raid_disk >= 0 &&
  			    !test_bit(Faulty, &rdev->flags) &&
  			    !test_bit(In_sync, &rdev->flags) &&
  			    rdev->recovery_offset < j)
  				j = rdev->recovery_offset;
  		rcu_read_unlock();
  	}
  
  	printk(KERN_INFO "md: %s of RAID array %s\n", desc, mdname(mddev));
  	printk(KERN_INFO "md: minimum _guaranteed_  speed:"
  		" %d KB/sec/disk.\n", speed_min(mddev));
  	printk(KERN_INFO "md: using maximum available idle IO bandwidth "
  	       "(but not more than %d KB/sec) for %s.\n",
  	       speed_max(mddev), desc);
  
  	is_mddev_idle(mddev, 1); /* this initializes IO event counters */
  
  	io_sectors = 0;
  	for (m = 0; m < SYNC_MARKS; m++) {
  		mark[m] = jiffies;
  		mark_cnt[m] = io_sectors;
  	}
  	last_mark = 0;
  	mddev->resync_mark = mark[last_mark];
  	mddev->resync_mark_cnt = mark_cnt[last_mark];
  
  	/*
  	 * Tune reconstruction:
  	 */
  	window = 32*(PAGE_SIZE/512);
  	printk(KERN_INFO "md: using %dk window, over a total of %lluk.\n",
  		window/2, (unsigned long long)max_sectors/2);
  
  	atomic_set(&mddev->recovery_active, 0);
  	last_check = 0;
  
  	if (j>2) {
  		printk(KERN_INFO
  		       "md: resuming %s of %s from checkpoint.\n",
  		       desc, mdname(mddev));
  		mddev->curr_resync = j;
  	}
  	mddev->curr_resync_completed = j;
  
  	while (j < max_sectors) {
  		sector_t sectors;
  
  		skipped = 0;
  
  		if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
  		    ((mddev->curr_resync > mddev->curr_resync_completed &&
  		      (mddev->curr_resync - mddev->curr_resync_completed)
  		      > (max_sectors >> 4)) ||
  		     (j - mddev->curr_resync_completed)*2
  		     >= mddev->resync_max - mddev->curr_resync_completed
  			    )) {
  			/* time to update curr_resync_completed */
  			wait_event(mddev->recovery_wait,
  				   atomic_read(&mddev->recovery_active) == 0);
  			mddev->curr_resync_completed = j;
  			set_bit(MD_CHANGE_CLEAN, &mddev->flags);
  			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
  		}
  
  		while (j >= mddev->resync_max && !kthread_should_stop()) {
  			/* As this condition is controlled by user-space,
  			 * we can block indefinitely, so use '_interruptible'
  			 * to avoid triggering warnings.
  			 */
  			flush_signals(current); /* just in case */
  			wait_event_interruptible(mddev->recovery_wait,
  						 mddev->resync_max > j
  						 || kthread_should_stop());
  		}
  
  		if (kthread_should_stop())
  			goto interrupted;
  
  		sectors = mddev->pers->sync_request(mddev, j, &skipped,
  						  currspeed < speed_min(mddev));
  		if (sectors == 0) {
  			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
  			goto out;
  		}
  
  		if (!skipped) { /* actual IO requested */
  			io_sectors += sectors;
  			atomic_add(sectors, &mddev->recovery_active);
  		}
  
  		j += sectors;
  		if (j>1) mddev->curr_resync = j;
  		mddev->curr_mark_cnt = io_sectors;
  		if (last_check == 0)
  			/* this is the earliers that rebuilt will be
  			 * visible in /proc/mdstat
  			 */
  			md_new_event(mddev);
  
  		if (last_check + window > io_sectors || j == max_sectors)
  			continue;
  
  		last_check = io_sectors;
  
  		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
  			break;
  
  	repeat:
  		if (time_after_eq(jiffies, mark[last_mark] + SYNC_MARK_STEP )) {
  			/* step marks */
  			int next = (last_mark+1) % SYNC_MARKS;
  
  			mddev->resync_mark = mark[next];
  			mddev->resync_mark_cnt = mark_cnt[next];
  			mark[next] = jiffies;
  			mark_cnt[next] = io_sectors - atomic_read(&mddev->recovery_active);
  			last_mark = next;
  		}
  
  		if (kthread_should_stop())
  			goto interrupted;
  
  		/*
  		 * this loop exits only if either when we are slower than
  		 * the 'hard' speed limit, or the system was IO-idle for
  		 * a jiffy.
  		 * the system might be non-idle CPU-wise, but we only care
  		 * about not overloading the IO subsystem. (things like an
  		 * e2fsck being done on the RAID array should execute fast)
  		 */
  		cond_resched();
  
  		currspeed = ((unsigned long)(io_sectors-mddev->resync_mark_cnt))/2
  			/((jiffies-mddev->resync_mark)/HZ +1) +1;
  
  		if (currspeed > speed_min(mddev)) {
  			if ((currspeed > speed_max(mddev)) ||
  					!is_mddev_idle(mddev, 0)) {
  				msleep(500);
  				goto repeat;
  			}
  		}
  	}
  	printk(KERN_INFO "md: %s: %s done.\n",mdname(mddev), desc);
  	/*
  	 * this also signals 'finished resyncing' to md_stop
  	 */
   out:
  	wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));
  
  	/* tell personality that we are finished */
  	mddev->pers->sync_request(mddev, max_sectors, &skipped, 1);
  
  	if (!test_bit(MD_RECOVERY_CHECK, &mddev->recovery) &&
  	    mddev->curr_resync > 2) {
  		if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
  			if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
  				if (mddev->curr_resync >= mddev->recovery_cp) {
  					printk(KERN_INFO
  					       "md: checkpointing %s of %s.\n",
  					       desc, mdname(mddev));
  					mddev->recovery_cp = mddev->curr_resync;
  				}
  			} else
  				mddev->recovery_cp = MaxSector;
  		} else {
  			if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
  				mddev->curr_resync = MaxSector;
  			rcu_read_lock();
  			list_for_each_entry_rcu(rdev, &mddev->disks, same_set)
  				if (rdev->raid_disk >= 0 &&
  				    mddev->delta_disks >= 0 &&
  				    !test_bit(Faulty, &rdev->flags) &&
  				    !test_bit(In_sync, &rdev->flags) &&
  				    rdev->recovery_offset < mddev->curr_resync)
  					rdev->recovery_offset = mddev->curr_resync;
  			rcu_read_unlock();
  		}
  	}
  	set_bit(MD_CHANGE_DEVS, &mddev->flags);
  
   skip:
  	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
  		/* We completed so min/max setting can be forgotten if used. */
  		if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
  			mddev->resync_min = 0;
  		mddev->resync_max = MaxSector;
  	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
  		mddev->resync_min = mddev->curr_resync_completed;
  	mddev->curr_resync = 0;
  	wake_up(&resync_wait);
  	set_bit(MD_RECOVERY_DONE, &mddev->recovery);
  	md_wakeup_thread(mddev->thread);
  	return;
  
   interrupted:
  	/*
  	 * got a signal, exit.
  	 */
  	printk(KERN_INFO
  	       "md: md_do_sync() got signal ... exiting\n");
  	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
  	goto out;
  
  }
  EXPORT_SYMBOL_GPL(md_do_sync);
  
  static int remove_and_add_spares(mddev_t *mddev)
  {
  	mdk_rdev_t *rdev;
  	int spares = 0;
  
  	mddev->curr_resync_completed = 0;
  
  	list_for_each_entry(rdev, &mddev->disks, same_set)
  		if (rdev->raid_disk >= 0 &&
  		    !test_bit(Blocked, &rdev->flags) &&
  		    (test_bit(Faulty, &rdev->flags) ||
  		     ! test_bit(In_sync, &rdev->flags)) &&
  		    atomic_read(&rdev->nr_pending)==0) {
  			if (mddev->pers->hot_remove_disk(
  				    mddev, rdev->raid_disk)==0) {
  				char nm[20];
  				sprintf(nm,"rd%d", rdev->raid_disk);
  				sysfs_remove_link(&mddev->kobj, nm);
  				rdev->raid_disk = -1;
  			}
  		}
  
  	if (mddev->degraded && !mddev->recovery_disabled) {
  		list_for_each_entry(rdev, &mddev->disks, same_set) {
  			if (rdev->raid_disk >= 0 &&
  			    !test_bit(In_sync, &rdev->flags) &&
  			    !test_bit(Faulty, &rdev->flags) &&
  			    !test_bit(Blocked, &rdev->flags))
  				spares++;
  			if (rdev->raid_disk < 0
  			    && !test_bit(Faulty, &rdev->flags)) {
  				rdev->recovery_offset = 0;
  				if (mddev->pers->
  				    hot_add_disk(mddev, rdev) == 0) {
  					char nm[20];
  					sprintf(nm, "rd%d", rdev->raid_disk);
  					if (sysfs_create_link(&mddev->kobj,
  							      &rdev->kobj, nm))
  						/* failure here is OK */;
  					spares++;
  					md_new_event(mddev);
  					set_bit(MD_CHANGE_DEVS, &mddev->flags);
  				} else
  					break;
  			}
  		}
  	}
  	return spares;
  }
  
  static void reap_sync_thread(mddev_t *mddev)
  {
  	mdk_rdev_t *rdev;
  
  	/* resync has finished, collect result */
  	md_unregister_thread(&mddev->sync_thread);
  	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
  	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
  		/* success...*/
  		/* activate any spares */
  		if (mddev->pers->spare_active(mddev))
  			sysfs_notify(&mddev->kobj, NULL,
  				     "degraded");
  	}
  	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
  	    mddev->pers->finish_reshape)
  		mddev->pers->finish_reshape(mddev);
  	md_update_sb(mddev, 1);
  
  	/* if array is no-longer degraded, then any saved_raid_disk
  	 * information must be scrapped
  	 */
  	if (!mddev->degraded)
  		list_for_each_entry(rdev, &mddev->disks, same_set)
  			rdev->saved_raid_disk = -1;
  
  	clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
  	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
  	clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
  	clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
  	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
  	/* flag recovery needed just to double check */
  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  	sysfs_notify_dirent_safe(mddev->sysfs_action);
  	md_new_event(mddev);
  }
  
  /*
   * This routine is regularly called by all per-raid-array threads to
   * deal with generic issues like resync and super-block update.
   * Raid personalities that don't have a thread (linear/raid0) do not
   * need this as they never do any recovery or update the superblock.
   *
   * It does not do any resync itself, but rather "forks" off other threads
   * to do that as needed.
   * When it is determined that resync is needed, we set MD_RECOVERY_RUNNING in
   * "->recovery" and create a thread at ->sync_thread.
   * When the thread finishes it sets MD_RECOVERY_DONE
   * and wakeups up this thread which will reap the thread and finish up.
   * This thread also removes any faulty devices (with nr_pending == 0).
   *
   * The overall approach is:
   *  1/ if the superblock needs updating, update it.
   *  2/ If a recovery thread is running, don't do anything else.
   *  3/ If recovery has finished, clean up, possibly marking spares active.
   *  4/ If there are any faulty devices, remove them.
   *  5/ If array is degraded, try to add spares devices
   *  6/ If array has spares or is not in-sync, start a resync thread.
   */
  void md_check_recovery(mddev_t *mddev)
  {
  	if (mddev->suspended)
  		return;
  
  	if (mddev->bitmap)
  		bitmap_daemon_work(mddev);
  
  	if (mddev->ro)
  		return;
  
  	if (signal_pending(current)) {
  		if (mddev->pers->sync_request && !mddev->external) {
  			printk(KERN_INFO "md: %s in immediate safe mode\n",
  			       mdname(mddev));
  			mddev->safemode = 2;
  		}
  		flush_signals(current);
  	}
  
  	if (mddev->ro && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))
  		return;
  	if ( ! (
  		(mddev->flags & ~ (1<<MD_CHANGE_PENDING)) ||
  		test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
  		test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
  		(mddev->external == 0 && mddev->safemode == 1) ||
  		(mddev->safemode == 2 && ! atomic_read(&mddev->writes_pending)
  		 && !mddev->in_sync && mddev->recovery_cp == MaxSector)
  		))
  		return;
  
  	if (mddev_trylock(mddev)) {
  		int spares = 0;
  
  		if (mddev->ro) {
  			/* Only thing we do on a ro array is remove
  			 * failed devices.
  			 */
  			mdk_rdev_t *rdev;
  			list_for_each_entry(rdev, &mddev->disks, same_set)
  				if (rdev->raid_disk >= 0 &&
  				    !test_bit(Blocked, &rdev->flags) &&
  				    test_bit(Faulty, &rdev->flags) &&
  				    atomic_read(&rdev->nr_pending)==0) {
  					if (mddev->pers->hot_remove_disk(
  						    mddev, rdev->raid_disk)==0) {
  						char nm[20];
  						sprintf(nm,"rd%d", rdev->raid_disk);
  						sysfs_remove_link(&mddev->kobj, nm);
  						rdev->raid_disk = -1;
  					}
  				}
  			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  			goto unlock;
  		}
  
  		if (!mddev->external) {
  			int did_change = 0;
  			spin_lock_irq(&mddev->write_lock);
  			if (mddev->safemode &&
  			    !atomic_read(&mddev->writes_pending) &&
  			    !mddev->in_sync &&
  			    mddev->recovery_cp == MaxSector) {
  				mddev->in_sync = 1;
  				did_change = 1;
  				set_bit(MD_CHANGE_CLEAN, &mddev->flags);
  			}
  			if (mddev->safemode == 1)
  				mddev->safemode = 0;
  			spin_unlock_irq(&mddev->write_lock);
  			if (did_change)
  				sysfs_notify_dirent_safe(mddev->sysfs_state);
  		}
  
  		if (mddev->flags)
  			md_update_sb(mddev, 0);
  
  		if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
  		    !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
  			/* resync/recovery still happening */
  			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  			goto unlock;
  		}
  		if (mddev->sync_thread) {
  			reap_sync_thread(mddev);
  			goto unlock;
  		}
  		/* Set RUNNING before clearing NEEDED to avoid
  		 * any transients in the value of "sync_action".
  		 */
  		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
  		clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  		/* Clear some bits that don't mean anything, but
  		 * might be left set
  		 */
  		clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
  		clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
  
  		if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
  			goto unlock;
  		/* no recovery is running.
  		 * remove any failed drives, then
  		 * add spares if possible.
  		 * Spare are also removed and re-added, to allow
  		 * the personality to fail the re-add.
  		 */
  
  		if (mddev->reshape_position != MaxSector) {
  			if (mddev->pers->check_reshape == NULL ||
  			    mddev->pers->check_reshape(mddev) != 0)
  				/* Cannot proceed */
  				goto unlock;
  			set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
  			clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
  		} else if ((spares = remove_and_add_spares(mddev))) {
  			clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
  			clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
  			clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
  			set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
  		} else if (mddev->recovery_cp < MaxSector) {
  			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
  			clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
  		} else if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
  			/* nothing to be done ... */
  			goto unlock;
  
  		if (mddev->pers->sync_request) {
  			if (spares && mddev->bitmap && ! mddev->bitmap->file) {
  				/* We are adding a device or devices to an array
  				 * which has the bitmap stored on all devices.
  				 * So make sure all bitmap pages get written
  				 */
  				bitmap_write_all(mddev->bitmap);
  			}
  			mddev->sync_thread = md_register_thread(md_do_sync,
  								mddev,
  								"resync");
  			if (!mddev->sync_thread) {
  				printk(KERN_ERR "%s: could not start resync"
  					" thread...\n",
  					mdname(mddev));
  				/* leave the spares where they are, it shouldn't hurt */
  				clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
  				clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
  				clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
  				clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
  				clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
  			} else
  				md_wakeup_thread(mddev->sync_thread);
  			sysfs_notify_dirent_safe(mddev->sysfs_action);
  			md_new_event(mddev);
  		}
  	unlock:
  		if (!mddev->sync_thread) {
  			clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
  			if (test_and_clear_bit(MD_RECOVERY_RECOVER,
  					       &mddev->recovery))
  				if (mddev->sysfs_action)
  					sysfs_notify_dirent_safe(mddev->sysfs_action);
  		}
  		mddev_unlock(mddev);
  	}
  }
  
  void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev)
  {
  	sysfs_notify_dirent_safe(rdev->sysfs_state);
  	wait_event_timeout(rdev->blocked_wait,
  			   !test_bit(Blocked, &rdev->flags),
  			   msecs_to_jiffies(5000));
  	rdev_dec_pending(rdev, mddev);
  }
  EXPORT_SYMBOL(md_wait_for_blocked_rdev);
  
  static int md_notify_reboot(struct notifier_block *this,
  			    unsigned long code, void *x)
  {
  	struct list_head *tmp;
  	mddev_t *mddev;
  
  	if ((code == SYS_DOWN) || (code == SYS_HALT) || (code == SYS_POWER_OFF)) {
  
  		printk(KERN_INFO "md: stopping all md devices.\n");
  
  		for_each_mddev(mddev, tmp)
  			if (mddev_trylock(mddev)) {
  				/* Force a switch to readonly even array
  				 * appears to still be in use.  Hence
  				 * the '100'.
  				 */
  				md_set_readonly(mddev, 100);
  				mddev_unlock(mddev);
  			}
  		/*
  		 * certain more exotic SCSI devices are known to be
  		 * volatile wrt too early system reboots. While the
  		 * right place to handle this issue is the given
  		 * driver, we do want to have a safe RAID driver ...
  		 */
  		mdelay(1000*1);
  	}
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block md_notifier = {
  	.notifier_call	= md_notify_reboot,
  	.next		= NULL,
  	.priority	= INT_MAX, /* before any real devices */
  };
  
  static void md_geninit(void)
  {
  	dprintk("md: sizeof(mdp_super_t) = %d\n", (int)sizeof(mdp_super_t));
  
  	proc_create("mdstat", S_IRUGO, NULL, &md_seq_fops);
  }
  
  static int __init md_init(void)
  {
  	int ret = -ENOMEM;
  
  	md_wq = alloc_workqueue("md", WQ_MEM_RECLAIM, 0);
  	if (!md_wq)
  		goto err_wq;
  
  	md_misc_wq = alloc_workqueue("md_misc", 0, 0);
  	if (!md_misc_wq)
  		goto err_misc_wq;
  
  	if ((ret = register_blkdev(MD_MAJOR, "md")) < 0)
  		goto err_md;
  
  	if ((ret = register_blkdev(0, "mdp")) < 0)
  		goto err_mdp;
  	mdp_major = ret;
  
  	blk_register_region(MKDEV(MD_MAJOR, 0), 1UL<<MINORBITS, THIS_MODULE,
  			    md_probe, NULL, NULL);
  	blk_register_region(MKDEV(mdp_major, 0), 1UL<<MINORBITS, THIS_MODULE,
  			    md_probe, NULL, NULL);
  
  	register_reboot_notifier(&md_notifier);
  	raid_table_header = register_sysctl_table(raid_root_table);
  
  	md_geninit();
  	return 0;
  
  err_mdp:
  	unregister_blkdev(MD_MAJOR, "md");
  err_md:
  	destroy_workqueue(md_misc_wq);
  err_misc_wq:
  	destroy_workqueue(md_wq);
  err_wq:
  	return ret;
  }
  
  #ifndef MODULE
  
  /*
   * Searches all registered partitions for autorun RAID arrays
   * at boot time.
   */
  
  static LIST_HEAD(all_detected_devices);
  struct detected_devices_node {
  	struct list_head list;
  	dev_t dev;
  };
  
  void md_autodetect_dev(dev_t dev)
  {
  	struct detected_devices_node *node_detected_dev;
  
  	node_detected_dev = kzalloc(sizeof(*node_detected_dev), GFP_KERNEL);
  	if (node_detected_dev) {
  		node_detected_dev->dev = dev;
  		list_add_tail(&node_detected_dev->list, &all_detected_devices);
  	} else {
  		printk(KERN_CRIT "md: md_autodetect_dev: kzalloc failed"
  			", skipping dev(%d,%d)\n", MAJOR(dev), MINOR(dev));
  	}
  }
  
  static void autostart_arrays(int part)
  {
  	mdk_rdev_t *rdev;
  	struct detected_devices_node *node_detected_dev;
  	dev_t dev;
  	int i_scanned, i_passed;
  
  	i_scanned = 0;
  	i_passed = 0;
  
  	printk(KERN_INFO "md: Autodetecting RAID arrays.\n");
  
  	while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
  		i_scanned++;
  		node_detected_dev = list_entry(all_detected_devices.next,
  					struct detected_devices_node, list);
  		list_del(&node_detected_dev->list);
  		dev = node_detected_dev->dev;
  		kfree(node_detected_dev);
  		rdev = md_import_device(dev,0, 90);
  		if (IS_ERR(rdev))
  			continue;
  
  		if (test_bit(Faulty, &rdev->flags)) {
  			MD_BUG();
  			continue;
  		}
  		set_bit(AutoDetected, &rdev->flags);
  		list_add(&rdev->same_set, &pending_raid_disks);
  		i_passed++;
  	}
  
  	printk(KERN_INFO "md: Scanned %d and added %d devices.\n",
  						i_scanned, i_passed);
  
  	autorun_devices(part);
  }
  
  #endif /* !MODULE */
  
  static __exit void md_exit(void)
  {
  	mddev_t *mddev;
  	struct list_head *tmp;
  
  	blk_unregister_region(MKDEV(MD_MAJOR,0), 1U << MINORBITS);
  	blk_unregister_region(MKDEV(mdp_major,0), 1U << MINORBITS);
  
  	unregister_blkdev(MD_MAJOR,"md");
  	unregister_blkdev(mdp_major, "mdp");
  	unregister_reboot_notifier(&md_notifier);
  	unregister_sysctl_table(raid_table_header);
  	remove_proc_entry("mdstat", NULL);
  	for_each_mddev(mddev, tmp) {
  		export_array(mddev);
  		mddev->hold_active = 0;
  	}
  	destroy_workqueue(md_misc_wq);
  	destroy_workqueue(md_wq);
  }
  
  subsys_initcall(md_init);
  module_exit(md_exit)
  
  static int get_ro(char *buffer, struct kernel_param *kp)
  {
  	return sprintf(buffer, "%d", start_readonly);
  }
  static int set_ro(const char *val, struct kernel_param *kp)
  {
  	char *e;
  	int num = simple_strtoul(val, &e, 10);
  	if (*val && (*e == '\0' || *e == '\n')) {
  		start_readonly = num;
  		return 0;
  	}
  	return -EINVAL;
  }
  
  module_param_call(start_ro, set_ro, get_ro, NULL, S_IRUSR|S_IWUSR);
  module_param(start_dirty_degraded, int, S_IRUGO|S_IWUSR);
  
  module_param_call(new_array, add_named_array, NULL, NULL, S_IWUSR);
  
  EXPORT_SYMBOL(register_md_personality);
  EXPORT_SYMBOL(unregister_md_personality);
  EXPORT_SYMBOL(md_error);
  EXPORT_SYMBOL(md_done_sync);
  EXPORT_SYMBOL(md_write_start);
  EXPORT_SYMBOL(md_write_end);
  EXPORT_SYMBOL(md_register_thread);
  EXPORT_SYMBOL(md_unregister_thread);
  EXPORT_SYMBOL(md_wakeup_thread);
  EXPORT_SYMBOL(md_check_recovery);
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("MD RAID framework");
  MODULE_ALIAS("md");
  MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);
  