text: /*
   *  pNFS functions to call and manage layout drivers.
   *
   *  Copyright (c) 2002 [year of first publication]
   *  The Regents of the University of Michigan
   *  All Rights Reserved
   *
   *  Dean Hildebrand <dhildebz@umich.edu>
   *
   *  Permission is granted to use, copy, create derivative works, and
   *  redistribute this software and such derivative works for any purpose,
   *  so long as the name of the University of Michigan is not used in
   *  any advertising or publicity pertaining to the use or distribution
   *  of this software without specific, written prior authorization. If
   *  the above copyright notice or any other identification of the
   *  University of Michigan is included in any copy of any portion of
   *  this software, then the disclaimer below must also be included.
   *
   *  This software is provided as is, without representation or warranty
   *  of any kind either express or implied, including without limitation
   *  the implied warranties of merchantability, fitness for a particular
   *  purpose, or noninfringement.  The Regents of the University of
   *  Michigan shall not be liable for any damages, including special,
   *  indirect, incidental, or consequential damages, with respect to any
   *  claim arising out of or in connection with the use of the software,
   *  even if it has been or is hereafter advised of the possibility of
   *  such damages.
   */
  
  #include <linux/nfs_fs.h>
  #include <linux/nfs_page.h>
  #include <linux/module.h>
  #include "internal.h"
  #include "pnfs.h"
  #include "iostat.h"
  #include "nfs4trace.h"
  
  #define NFSDBG_FACILITY		NFSDBG_PNFS
  #define PNFS_LAYOUTGET_RETRY_TIMEOUT (120*HZ)
  
  /* Locking:
   *
   * pnfs_spinlock:
   *      protects pnfs_modules_tbl.
   */
  static DEFINE_SPINLOCK(pnfs_spinlock);
  
  /*
   * pnfs_modules_tbl holds all pnfs modules
   */
  static LIST_HEAD(pnfs_modules_tbl);
  
  /* Return the registered pnfs layout driver module matching given id */
  static struct pnfs_layoutdriver_type *
  find_pnfs_driver_locked(u32 id)
  {
  	struct pnfs_layoutdriver_type *local;
  
  	list_for_each_entry(local, &pnfs_modules_tbl, pnfs_tblid)
  		if (local->id == id)
  			goto out;
  	local = NULL;
  out:
  	dprintk("%s: Searching for id %u, found %p\n", __func__, id, local);
  	return local;
  }
  
  static struct pnfs_layoutdriver_type *
  find_pnfs_driver(u32 id)
  {
  	struct pnfs_layoutdriver_type *local;
  
  	spin_lock(&pnfs_spinlock);
  	local = find_pnfs_driver_locked(id);
  	if (local != NULL && !try_module_get(local->owner)) {
  		dprintk("%s: Could not grab reference on module\n", __func__);
  		local = NULL;
  	}
  	spin_unlock(&pnfs_spinlock);
  	return local;
  }
  
  void
  unset_pnfs_layoutdriver(struct nfs_server *nfss)
  {
  	if (nfss->pnfs_curr_ld) {
  		if (nfss->pnfs_curr_ld->clear_layoutdriver)
  			nfss->pnfs_curr_ld->clear_layoutdriver(nfss);
  		/* Decrement the MDS count. Purge the deviceid cache if zero */
  		if (atomic_dec_and_test(&nfss->nfs_client->cl_mds_count))
  			nfs4_deviceid_purge_client(nfss->nfs_client);
  		module_put(nfss->pnfs_curr_ld->owner);
  	}
  	nfss->pnfs_curr_ld = NULL;
  }
  
  /*
   * Try to set the server's pnfs module to the pnfs layout type specified by id.
   * Currently only one pNFS layout driver per filesystem is supported.
   *
   * @id layout type. Zero (illegal layout type) indicates pNFS not in use.
   */
  void
  set_pnfs_layoutdriver(struct nfs_server *server, const struct nfs_fh *mntfh,
  		      u32 id)
  {
  	struct pnfs_layoutdriver_type *ld_type = NULL;
  
  	if (id == 0)
  		goto out_no_driver;
  	if (!(server->nfs_client->cl_exchange_flags &
  		 (EXCHGID4_FLAG_USE_NON_PNFS | EXCHGID4_FLAG_USE_PNFS_MDS))) {
  		printk(KERN_ERR "NFS: %s: id %u cl_exchange_flags 0x%x\n",
  			__func__, id, server->nfs_client->cl_exchange_flags);
  		goto out_no_driver;
  	}
  	ld_type = find_pnfs_driver(id);
  	if (!ld_type) {
  		request_module("%s-%u", LAYOUT_NFSV4_1_MODULE_PREFIX, id);
  		ld_type = find_pnfs_driver(id);
  		if (!ld_type) {
  			dprintk("%s: No pNFS module found for %u.\n",
  				__func__, id);
  			goto out_no_driver;
  		}
  	}
  	server->pnfs_curr_ld = ld_type;
  	if (ld_type->set_layoutdriver
  	    && ld_type->set_layoutdriver(server, mntfh)) {
  		printk(KERN_ERR "NFS: %s: Error initializing pNFS layout "
  			"driver %u.\n", __func__, id);
  		module_put(ld_type->owner);
  		goto out_no_driver;
  	}
  	/* Bump the MDS count */
  	atomic_inc(&server->nfs_client->cl_mds_count);
  
  	dprintk("%s: pNFS module for %u set\n", __func__, id);
  	return;
  
  out_no_driver:
  	dprintk("%s: Using NFSv4 I/O\n", __func__);
  	server->pnfs_curr_ld = NULL;
  }
  
  int
  pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
  {
  	int status = -EINVAL;
  	struct pnfs_layoutdriver_type *tmp;
  
  	if (ld_type->id == 0) {
  		printk(KERN_ERR "NFS: %s id 0 is reserved\n", __func__);
  		return status;
  	}
  	if (!ld_type->alloc_lseg || !ld_type->free_lseg) {
  		printk(KERN_ERR "NFS: %s Layout driver must provide "
  		       "alloc_lseg and free_lseg.\n", __func__);
  		return status;
  	}
  
  	spin_lock(&pnfs_spinlock);
  	tmp = find_pnfs_driver_locked(ld_type->id);
  	if (!tmp) {
  		list_add(&ld_type->pnfs_tblid, &pnfs_modules_tbl);
  		status = 0;
  		dprintk("%s Registering id:%u name:%s\n", __func__, ld_type->id,
  			ld_type->name);
  	} else {
  		printk(KERN_ERR "NFS: %s Module with id %d already loaded!\n",
  			__func__, ld_type->id);
  	}
  	spin_unlock(&pnfs_spinlock);
  
  	return status;
  }
  EXPORT_SYMBOL_GPL(pnfs_register_layoutdriver);
  
  void
  pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
  {
  	dprintk("%s Deregistering id:%u\n", __func__, ld_type->id);
  	spin_lock(&pnfs_spinlock);
  	list_del(&ld_type->pnfs_tblid);
  	spin_unlock(&pnfs_spinlock);
  }
  EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver);
  
  /*
   * pNFS client layout cache
   */
  
  /* Need to hold i_lock if caller does not already hold reference */
  void
  pnfs_get_layout_hdr(struct pnfs_layout_hdr *lo)
  {
  	atomic_inc(&lo->plh_refcount);
  }
  
  static struct pnfs_layout_hdr *
  pnfs_alloc_layout_hdr(struct inode *ino, gfp_t gfp_flags)
  {
  	struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;
  	return ld->alloc_layout_hdr(ino, gfp_flags);
  }
  
  static void
  pnfs_free_layout_hdr(struct pnfs_layout_hdr *lo)
  {
  	struct nfs_server *server = NFS_SERVER(lo->plh_inode);
  	struct pnfs_layoutdriver_type *ld = server->pnfs_curr_ld;
  
  	if (!list_empty(&lo->plh_layouts)) {
  		struct nfs_client *clp = server->nfs_client;
  
  		spin_lock(&clp->cl_lock);
  		list_del_init(&lo->plh_layouts);
  		spin_unlock(&clp->cl_lock);
  	}
  	put_rpccred(lo->plh_lc_cred);
  	return ld->free_layout_hdr(lo);
  }
  
  static void
  pnfs_detach_layout_hdr(struct pnfs_layout_hdr *lo)
  {
  	struct nfs_inode *nfsi = NFS_I(lo->plh_inode);
  	dprintk("%s: freeing layout cache %p\n", __func__, lo);
  	nfsi->layout = NULL;
  	/* Reset MDS Threshold I/O counters */
  	nfsi->write_io = 0;
  	nfsi->read_io = 0;
  }
  
  void
  pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo)
  {
  	struct inode *inode = lo->plh_inode;
  
  	if (atomic_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) {
  		pnfs_detach_layout_hdr(lo);
  		spin_unlock(&inode->i_lock);
  		pnfs_free_layout_hdr(lo);
  	}
  }
  
  static int
  pnfs_iomode_to_fail_bit(u32 iomode)
  {
  	return iomode == IOMODE_RW ?
  		NFS_LAYOUT_RW_FAILED : NFS_LAYOUT_RO_FAILED;
  }
  
  static void
  pnfs_layout_set_fail_bit(struct pnfs_layout_hdr *lo, int fail_bit)
  {
  	lo->plh_retry_timestamp = jiffies;
  	if (!test_and_set_bit(fail_bit, &lo->plh_flags))
  		atomic_inc(&lo->plh_refcount);
  }
  
  static void
  pnfs_layout_clear_fail_bit(struct pnfs_layout_hdr *lo, int fail_bit)
  {
  	if (test_and_clear_bit(fail_bit, &lo->plh_flags))
  		atomic_dec(&lo->plh_refcount);
  }
  
  static void
  pnfs_layout_io_set_failed(struct pnfs_layout_hdr *lo, u32 iomode)
  {
  	struct inode *inode = lo->plh_inode;
  	struct pnfs_layout_range range = {
  		.iomode = iomode,
  		.offset = 0,
  		.length = NFS4_MAX_UINT64,
  	};
  	LIST_HEAD(head);
  
  	spin_lock(&inode->i_lock);
  	pnfs_layout_set_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
  	pnfs_mark_matching_lsegs_invalid(lo, &head, &range);
  	spin_unlock(&inode->i_lock);
  	pnfs_free_lseg_list(&head);
  	dprintk("%s Setting layout IOMODE_%s fail bit\n", __func__,
  			iomode == IOMODE_RW ?  "RW" : "READ");
  }
  
  static bool
  pnfs_layout_io_test_failed(struct pnfs_layout_hdr *lo, u32 iomode)
  {
  	unsigned long start, end;
  	int fail_bit = pnfs_iomode_to_fail_bit(iomode);
  
  	if (test_bit(fail_bit, &lo->plh_flags) == 0)
  		return false;
  	end = jiffies;
  	start = end - PNFS_LAYOUTGET_RETRY_TIMEOUT;
  	if (!time_in_range(lo->plh_retry_timestamp, start, end)) {
  		/* It is time to retry the failed layoutgets */
  		pnfs_layout_clear_fail_bit(lo, fail_bit);
  		return false;
  	}
  	return true;
  }
  
  static void
  init_lseg(struct pnfs_layout_hdr *lo, struct pnfs_layout_segment *lseg)
  {
  	INIT_LIST_HEAD(&lseg->pls_list);
  	INIT_LIST_HEAD(&lseg->pls_lc_list);
  	atomic_set(&lseg->pls_refcount, 1);
  	smp_mb();
  	set_bit(NFS_LSEG_VALID, &lseg->pls_flags);
  	lseg->pls_layout = lo;
  }
  
  static void pnfs_free_lseg(struct pnfs_layout_segment *lseg)
  {
  	struct inode *ino = lseg->pls_layout->plh_inode;
  
  	NFS_SERVER(ino)->pnfs_curr_ld->free_lseg(lseg);
  }
  
  static void
  pnfs_layout_remove_lseg(struct pnfs_layout_hdr *lo,
  		struct pnfs_layout_segment *lseg)
  {
  	struct inode *inode = lo->plh_inode;
  
  	WARN_ON(test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
  	list_del_init(&lseg->pls_list);
  	/* Matched by pnfs_get_layout_hdr in pnfs_layout_insert_lseg */
  	atomic_dec(&lo->plh_refcount);
  	if (list_empty(&lo->plh_segs))
  		clear_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);
  	rpc_wake_up(&NFS_SERVER(inode)->roc_rpcwaitq);
  }
  
  void
  pnfs_put_lseg(struct pnfs_layout_segment *lseg)
  {
  	struct pnfs_layout_hdr *lo;
  	struct inode *inode;
  
  	if (!lseg)
  		return;
  
  	dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
  		atomic_read(&lseg->pls_refcount),
  		test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
  	lo = lseg->pls_layout;
  	inode = lo->plh_inode;
  	if (atomic_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
  		pnfs_get_layout_hdr(lo);
  		pnfs_layout_remove_lseg(lo, lseg);
  		spin_unlock(&inode->i_lock);
  		pnfs_free_lseg(lseg);
  		pnfs_put_layout_hdr(lo);
  	}
  }
  EXPORT_SYMBOL_GPL(pnfs_put_lseg);
  
  static void pnfs_free_lseg_async_work(struct work_struct *work)
  {
  	struct pnfs_layout_segment *lseg;
  	struct pnfs_layout_hdr *lo;
  
  	lseg = container_of(work, struct pnfs_layout_segment, pls_work);
  	lo = lseg->pls_layout;
  
  	pnfs_free_lseg(lseg);
  	pnfs_put_layout_hdr(lo);
  }
  
  static void pnfs_free_lseg_async(struct pnfs_layout_segment *lseg)
  {
  	INIT_WORK(&lseg->pls_work, pnfs_free_lseg_async_work);
  	schedule_work(&lseg->pls_work);
  }
  
  void
  pnfs_put_lseg_locked(struct pnfs_layout_segment *lseg)
  {
  	if (!lseg)
  		return;
  
  	assert_spin_locked(&lseg->pls_layout->plh_inode->i_lock);
  
  	dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
  		atomic_read(&lseg->pls_refcount),
  		test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
  	if (atomic_dec_and_test(&lseg->pls_refcount)) {
  		struct pnfs_layout_hdr *lo = lseg->pls_layout;
  		pnfs_get_layout_hdr(lo);
  		pnfs_layout_remove_lseg(lo, lseg);
  		pnfs_free_lseg_async(lseg);
  	}
  }
  EXPORT_SYMBOL_GPL(pnfs_put_lseg_locked);
  
  static u64
  end_offset(u64 start, u64 len)
  {
  	u64 end;
  
  	end = start + len;
  	return end >= start ? end : NFS4_MAX_UINT64;
  }
  
  /*
   * is l2 fully contained in l1?
   *   start1                             end1
   *   [----------------------------------)
   *           start2           end2
   *           [----------------)
   */
  static bool
  pnfs_lseg_range_contained(const struct pnfs_layout_range *l1,
  		 const struct pnfs_layout_range *l2)
  {
  	u64 start1 = l1->offset;
  	u64 end1 = end_offset(start1, l1->length);
  	u64 start2 = l2->offset;
  	u64 end2 = end_offset(start2, l2->length);
  
  	return (start1 <= start2) && (end1 >= end2);
  }
  
  /*
   * is l1 and l2 intersecting?
   *   start1                             end1
   *   [----------------------------------)
   *                              start2           end2
   *                              [----------------)
   */
  static bool
  pnfs_lseg_range_intersecting(const struct pnfs_layout_range *l1,
  		    const struct pnfs_layout_range *l2)
  {
  	u64 start1 = l1->offset;
  	u64 end1 = end_offset(start1, l1->length);
  	u64 start2 = l2->offset;
  	u64 end2 = end_offset(start2, l2->length);
  
  	return (end1 == NFS4_MAX_UINT64 || end1 > start2) &&
  	       (end2 == NFS4_MAX_UINT64 || end2 > start1);
  }
  
  static bool
  should_free_lseg(const struct pnfs_layout_range *lseg_range,
  		 const struct pnfs_layout_range *recall_range)
  {
  	return (recall_range->iomode == IOMODE_ANY ||
  		lseg_range->iomode == recall_range->iomode) &&
  	       pnfs_lseg_range_intersecting(lseg_range, recall_range);
  }
  
  static bool pnfs_lseg_dec_and_remove_zero(struct pnfs_layout_segment *lseg,
  		struct list_head *tmp_list)
  {
  	if (!atomic_dec_and_test(&lseg->pls_refcount))
  		return false;
  	pnfs_layout_remove_lseg(lseg->pls_layout, lseg);
  	list_add(&lseg->pls_list, tmp_list);
  	return true;
  }
  
  /* Returns 1 if lseg is removed from list, 0 otherwise */
  static int mark_lseg_invalid(struct pnfs_layout_segment *lseg,
  			     struct list_head *tmp_list)
  {
  	int rv = 0;
  
  	if (test_and_clear_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
  		/* Remove the reference keeping the lseg in the
  		 * list.  It will now be removed when all
  		 * outstanding io is finished.
  		 */
  		dprintk("%s: lseg %p ref %d\n", __func__, lseg,
  			atomic_read(&lseg->pls_refcount));
  		if (pnfs_lseg_dec_and_remove_zero(lseg, tmp_list))
  			rv = 1;
  	}
  	return rv;
  }
  
  /* Returns count of number of matching invalid lsegs remaining in list
   * after call.
   */
  int
  pnfs_mark_matching_lsegs_invalid(struct pnfs_layout_hdr *lo,
  			    struct list_head *tmp_list,
  			    struct pnfs_layout_range *recall_range)
  {
  	struct pnfs_layout_segment *lseg, *next;
  	int invalid = 0, removed = 0;
  
  	dprintk("%s:Begin lo %p\n", __func__, lo);
  
  	if (list_empty(&lo->plh_segs))
  		return 0;
  	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list)
  		if (!recall_range ||
  		    should_free_lseg(&lseg->pls_range, recall_range)) {
  			dprintk("%s: freeing lseg %p iomode %d "
  				"offset %llu length %llu\n", __func__,
  				lseg, lseg->pls_range.iomode, lseg->pls_range.offset,
  				lseg->pls_range.length);
  			invalid++;
  			removed += mark_lseg_invalid(lseg, tmp_list);
  		}
  	dprintk("%s:Return %i\n", __func__, invalid - removed);
  	return invalid - removed;
  }
  
  /* note free_me must contain lsegs from a single layout_hdr */
  void
  pnfs_free_lseg_list(struct list_head *free_me)
  {
  	struct pnfs_layout_segment *lseg, *tmp;
  
  	if (list_empty(free_me))
  		return;
  
  	list_for_each_entry_safe(lseg, tmp, free_me, pls_list) {
  		list_del(&lseg->pls_list);
  		pnfs_free_lseg(lseg);
  	}
  }
  
  void
  pnfs_destroy_layout(struct nfs_inode *nfsi)
  {
  	struct pnfs_layout_hdr *lo;
  	LIST_HEAD(tmp_list);
  
  	spin_lock(&nfsi->vfs_inode.i_lock);
  	lo = nfsi->layout;
  	if (lo) {
  		lo->plh_block_lgets++; /* permanently block new LAYOUTGETs */
  		pnfs_mark_matching_lsegs_invalid(lo, &tmp_list, NULL);
  		pnfs_get_layout_hdr(lo);
  		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RO_FAILED);
  		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RW_FAILED);
  		spin_unlock(&nfsi->vfs_inode.i_lock);
  		pnfs_free_lseg_list(&tmp_list);
  		pnfs_put_layout_hdr(lo);
  	} else
  		spin_unlock(&nfsi->vfs_inode.i_lock);
  }
  EXPORT_SYMBOL_GPL(pnfs_destroy_layout);
  
  static bool
  pnfs_layout_add_bulk_destroy_list(struct inode *inode,
  		struct list_head *layout_list)
  {
  	struct pnfs_layout_hdr *lo;
  	bool ret = false;
  
  	spin_lock(&inode->i_lock);
  	lo = NFS_I(inode)->layout;
  	if (lo != NULL && list_empty(&lo->plh_bulk_destroy)) {
  		pnfs_get_layout_hdr(lo);
  		list_add(&lo->plh_bulk_destroy, layout_list);
  		ret = true;
  	}
  	spin_unlock(&inode->i_lock);
  	return ret;
  }
  
  /* Caller must hold rcu_read_lock and clp->cl_lock */
  static int
  pnfs_layout_bulk_destroy_byserver_locked(struct nfs_client *clp,
  		struct nfs_server *server,
  		struct list_head *layout_list)
  {
  	struct pnfs_layout_hdr *lo, *next;
  	struct inode *inode;
  
  	list_for_each_entry_safe(lo, next, &server->layouts, plh_layouts) {
  		inode = igrab(lo->plh_inode);
  		if (inode == NULL)
  			continue;
  		list_del_init(&lo->plh_layouts);
  		if (pnfs_layout_add_bulk_destroy_list(inode, layout_list))
  			continue;
  		rcu_read_unlock();
  		spin_unlock(&clp->cl_lock);
  		iput(inode);
  		spin_lock(&clp->cl_lock);
  		rcu_read_lock();
  		return -EAGAIN;
  	}
  	return 0;
  }
  
  static int
  pnfs_layout_free_bulk_destroy_list(struct list_head *layout_list,
  		bool is_bulk_recall)
  {
  	struct pnfs_layout_hdr *lo;
  	struct inode *inode;
  	struct pnfs_layout_range range = {
  		.iomode = IOMODE_ANY,
  		.offset = 0,
  		.length = NFS4_MAX_UINT64,
  	};
  	LIST_HEAD(lseg_list);
  	int ret = 0;
  
  	while (!list_empty(layout_list)) {
  		lo = list_entry(layout_list->next, struct pnfs_layout_hdr,
  				plh_bulk_destroy);
  		dprintk("%s freeing layout for inode %lu\n", __func__,
  			lo->plh_inode->i_ino);
  		inode = lo->plh_inode;
  
  		pnfs_layoutcommit_inode(inode, false);
  
  		spin_lock(&inode->i_lock);
  		list_del_init(&lo->plh_bulk_destroy);
  		lo->plh_block_lgets++; /* permanently block new LAYOUTGETs */
  		if (is_bulk_recall)
  			set_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);
  		if (pnfs_mark_matching_lsegs_invalid(lo, &lseg_list, &range))
  			ret = -EAGAIN;
  		spin_unlock(&inode->i_lock);
  		pnfs_free_lseg_list(&lseg_list);
  		pnfs_put_layout_hdr(lo);
  		iput(inode);
  	}
  	return ret;
  }
  
  int
  pnfs_destroy_layouts_byfsid(struct nfs_client *clp,
  		struct nfs_fsid *fsid,
  		bool is_recall)
  {
  	struct nfs_server *server;
  	LIST_HEAD(layout_list);
  
  	spin_lock(&clp->cl_lock);
  	rcu_read_lock();
  restart:
  	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
  		if (memcmp(&server->fsid, fsid, sizeof(*fsid)) != 0)
  			continue;
  		if (pnfs_layout_bulk_destroy_byserver_locked(clp,
  				server,
  				&layout_list) != 0)
  			goto restart;
  	}
  	rcu_read_unlock();
  	spin_unlock(&clp->cl_lock);
  
  	if (list_empty(&layout_list))
  		return 0;
  	return pnfs_layout_free_bulk_destroy_list(&layout_list, is_recall);
  }
  
  int
  pnfs_destroy_layouts_byclid(struct nfs_client *clp,
  		bool is_recall)
  {
  	struct nfs_server *server;
  	LIST_HEAD(layout_list);
  
  	spin_lock(&clp->cl_lock);
  	rcu_read_lock();
  restart:
  	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
  		if (pnfs_layout_bulk_destroy_byserver_locked(clp,
  					server,
  					&layout_list) != 0)
  			goto restart;
  	}
  	rcu_read_unlock();
  	spin_unlock(&clp->cl_lock);
  
  	if (list_empty(&layout_list))
  		return 0;
  	return pnfs_layout_free_bulk_destroy_list(&layout_list, is_recall);
  }
  
  /*
   * Called by the state manger to remove all layouts established under an
   * expired lease.
   */
  void
  pnfs_destroy_all_layouts(struct nfs_client *clp)
  {
  	nfs4_deviceid_mark_client_invalid(clp);
  	nfs4_deviceid_purge_client(clp);
  
  	pnfs_destroy_layouts_byclid(clp, false);
  }
  
  /*
   * Compare 2 layout stateid sequence ids, to see which is newer,
   * taking into account wraparound issues.
   */
  static bool pnfs_seqid_is_newer(u32 s1, u32 s2)
  {
  	return (s32)(s1 - s2) > 0;
  }
  
  /* update lo->plh_stateid with new if is more recent */
  void
  pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo, const nfs4_stateid *new,
  			bool update_barrier)
  {
  	u32 oldseq, newseq, new_barrier;
  	int empty = list_empty(&lo->plh_segs);
  
  	oldseq = be32_to_cpu(lo->plh_stateid.seqid);
  	newseq = be32_to_cpu(new->seqid);
  	if (empty || pnfs_seqid_is_newer(newseq, oldseq)) {
  		nfs4_stateid_copy(&lo->plh_stateid, new);
  		if (update_barrier) {
  			new_barrier = be32_to_cpu(new->seqid);
  		} else {
  			/* Because of wraparound, we want to keep the barrier
  			 * "close" to the current seqids.
  			 */
  			new_barrier = newseq - atomic_read(&lo->plh_outstanding);
  		}
  		if (empty || pnfs_seqid_is_newer(new_barrier, lo->plh_barrier))
  			lo->plh_barrier = new_barrier;
  	}
  }
  
  static bool
  pnfs_layout_stateid_blocked(const struct pnfs_layout_hdr *lo,
  		const nfs4_stateid *stateid)
  {
  	u32 seqid = be32_to_cpu(stateid->seqid);
  
  	return !pnfs_seqid_is_newer(seqid, lo->plh_barrier);
  }
  
  /* lget is set to 1 if called from inside send_layoutget call chain */
  static bool
  pnfs_layoutgets_blocked(const struct pnfs_layout_hdr *lo, int lget)
  {
  	return lo->plh_block_lgets ||
  		test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags) ||
  		(list_empty(&lo->plh_segs) &&
  		 (atomic_read(&lo->plh_outstanding) > lget));
  }
  
  int
  pnfs_choose_layoutget_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo,
  			      struct nfs4_state *open_state)
  {
  	int status = 0;
  
  	dprintk("--> %s\n", __func__);
  	spin_lock(&lo->plh_inode->i_lock);
  	if (pnfs_layoutgets_blocked(lo, 1)) {
  		status = -EAGAIN;
  	} else if (!nfs4_valid_open_stateid(open_state)) {
  		status = -EBADF;
  	} else if (list_empty(&lo->plh_segs) ||
  		   test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags)) {
  		int seq;
  
  		do {
  			seq = read_seqbegin(&open_state->seqlock);
  			nfs4_stateid_copy(dst, &open_state->stateid);
  		} while (read_seqretry(&open_state->seqlock, seq));
  	} else
  		nfs4_stateid_copy(dst, &lo->plh_stateid);
  	spin_unlock(&lo->plh_inode->i_lock);
  	dprintk("<-- %s\n", __func__);
  	return status;
  }
  
  /*
  * Get layout from server.
  *    for now, assume that whole file layouts are requested.
  *    arg->offset: 0
  *    arg->length: all ones
  */
  static struct pnfs_layout_segment *
  send_layoutget(struct pnfs_layout_hdr *lo,
  	   struct nfs_open_context *ctx,
  	   struct pnfs_layout_range *range,
  	   gfp_t gfp_flags)
  {
  	struct inode *ino = lo->plh_inode;
  	struct nfs_server *server = NFS_SERVER(ino);
  	struct nfs4_layoutget *lgp;
  	struct pnfs_layout_segment *lseg;
  
  	dprintk("--> %s\n", __func__);
  
  	lgp = kzalloc(sizeof(*lgp), gfp_flags);
  	if (lgp == NULL)
  		return NULL;
  
  	lgp->args.minlength = PAGE_CACHE_SIZE;
  	if (lgp->args.minlength > range->length)
  		lgp->args.minlength = range->length;
  	lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
  	lgp->args.range = *range;
  	lgp->args.type = server->pnfs_curr_ld->id;
  	lgp->args.inode = ino;
  	lgp->args.ctx = get_nfs_open_context(ctx);
  	lgp->gfp_flags = gfp_flags;
  	lgp->cred = lo->plh_lc_cred;
  
  	/* Synchronously retrieve layout information from server and
  	 * store in lseg.
  	 */
  	lseg = nfs4_proc_layoutget(lgp, gfp_flags);
  	if (IS_ERR(lseg)) {
  		switch (PTR_ERR(lseg)) {
  		case -ENOMEM:
  		case -ERESTARTSYS:
  			break;
  		default:
  			/* remember that LAYOUTGET failed and suspend trying */
  			pnfs_layout_io_set_failed(lo, range->iomode);
  		}
  		return NULL;
  	}
  
  	return lseg;
  }
  
  static void pnfs_clear_layoutcommit(struct inode *inode,
  		struct list_head *head)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	struct pnfs_layout_segment *lseg, *tmp;
  
  	if (!test_and_clear_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
  		return;
  	list_for_each_entry_safe(lseg, tmp, &nfsi->layout->plh_segs, pls_list) {
  		if (!test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
  			continue;
  		pnfs_lseg_dec_and_remove_zero(lseg, head);
  	}
  }
  
  /*
   * Initiates a LAYOUTRETURN(FILE), and removes the pnfs_layout_hdr
   * when the layout segment list is empty.
   *
   * Note that a pnfs_layout_hdr can exist with an empty layout segment
   * list when LAYOUTGET has failed, or when LAYOUTGET succeeded, but the
   * deviceid is marked invalid.
   */
  int
  _pnfs_return_layout(struct inode *ino)
  {
  	struct pnfs_layout_hdr *lo = NULL;
  	struct nfs_inode *nfsi = NFS_I(ino);
  	LIST_HEAD(tmp_list);
  	struct nfs4_layoutreturn *lrp;
  	nfs4_stateid stateid;
  	int status = 0, empty;
  
  	dprintk("NFS: %s for inode %lu\n", __func__, ino->i_ino);
  
  	spin_lock(&ino->i_lock);
  	lo = nfsi->layout;
  	if (!lo) {
  		spin_unlock(&ino->i_lock);
  		dprintk("NFS: %s no layout to return\n", __func__);
  		goto out;
  	}
  	stateid = nfsi->layout->plh_stateid;
  	/* Reference matched in nfs4_layoutreturn_release */
  	pnfs_get_layout_hdr(lo);
  	empty = list_empty(&lo->plh_segs);
  	pnfs_clear_layoutcommit(ino, &tmp_list);
  	pnfs_mark_matching_lsegs_invalid(lo, &tmp_list, NULL);
  
  	if (NFS_SERVER(ino)->pnfs_curr_ld->return_range) {
  		struct pnfs_layout_range range = {
  			.iomode		= IOMODE_ANY,
  			.offset		= 0,
  			.length		= NFS4_MAX_UINT64,
  		};
  		NFS_SERVER(ino)->pnfs_curr_ld->return_range(lo, &range);
  	}
  
  	/* Don't send a LAYOUTRETURN if list was initially empty */
  	if (empty) {
  		spin_unlock(&ino->i_lock);
  		pnfs_put_layout_hdr(lo);
  		dprintk("NFS: %s no layout segments to return\n", __func__);
  		goto out;
  	}
  
  	set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
  	lo->plh_block_lgets++;
  	spin_unlock(&ino->i_lock);
  	pnfs_free_lseg_list(&tmp_list);
  
  	lrp = kzalloc(sizeof(*lrp), GFP_KERNEL);
  	if (unlikely(lrp == NULL)) {
  		status = -ENOMEM;
  		spin_lock(&ino->i_lock);
  		lo->plh_block_lgets--;
  		spin_unlock(&ino->i_lock);
  		pnfs_put_layout_hdr(lo);
  		goto out;
  	}
  
  	lrp->args.stateid = stateid;
  	lrp->args.layout_type = NFS_SERVER(ino)->pnfs_curr_ld->id;
  	lrp->args.inode = ino;
  	lrp->args.layout = lo;
  	lrp->clp = NFS_SERVER(ino)->nfs_client;
  	lrp->cred = lo->plh_lc_cred;
  
  	status = nfs4_proc_layoutreturn(lrp);
  out:
  	dprintk("<-- %s status: %d\n", __func__, status);
  	return status;
  }
  EXPORT_SYMBOL_GPL(_pnfs_return_layout);
  
  int
  pnfs_commit_and_return_layout(struct inode *inode)
  {
  	struct pnfs_layout_hdr *lo;
  	int ret;
  
  	spin_lock(&inode->i_lock);
  	lo = NFS_I(inode)->layout;
  	if (lo == NULL) {
  		spin_unlock(&inode->i_lock);
  		return 0;
  	}
  	pnfs_get_layout_hdr(lo);
  	/* Block new layoutgets and read/write to ds */
  	lo->plh_block_lgets++;
  	spin_unlock(&inode->i_lock);
  	filemap_fdatawait(inode->i_mapping);
  	ret = pnfs_layoutcommit_inode(inode, true);
  	if (ret == 0)
  		ret = _pnfs_return_layout(inode);
  	spin_lock(&inode->i_lock);
  	lo->plh_block_lgets--;
  	spin_unlock(&inode->i_lock);
  	pnfs_put_layout_hdr(lo);
  	return ret;
  }
  
  bool pnfs_roc(struct inode *ino)
  {
  	struct pnfs_layout_hdr *lo;
  	struct pnfs_layout_segment *lseg, *tmp;
  	LIST_HEAD(tmp_list);
  	bool found = false;
  
  	spin_lock(&ino->i_lock);
  	lo = NFS_I(ino)->layout;
  	if (!lo || !test_and_clear_bit(NFS_LAYOUT_ROC, &lo->plh_flags) ||
  	    test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags))
  		goto out_nolayout;
  	list_for_each_entry_safe(lseg, tmp, &lo->plh_segs, pls_list)
  		if (test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
  			mark_lseg_invalid(lseg, &tmp_list);
  			found = true;
  		}
  	if (!found)
  		goto out_nolayout;
  	lo->plh_block_lgets++;
  	pnfs_get_layout_hdr(lo); /* matched in pnfs_roc_release */
  	spin_unlock(&ino->i_lock);
  	pnfs_free_lseg_list(&tmp_list);
  	return true;
  
  out_nolayout:
  	spin_unlock(&ino->i_lock);
  	return false;
  }
  
  void pnfs_roc_release(struct inode *ino)
  {
  	struct pnfs_layout_hdr *lo;
  
  	spin_lock(&ino->i_lock);
  	lo = NFS_I(ino)->layout;
  	lo->plh_block_lgets--;
  	if (atomic_dec_and_test(&lo->plh_refcount)) {
  		pnfs_detach_layout_hdr(lo);
  		spin_unlock(&ino->i_lock);
  		pnfs_free_layout_hdr(lo);
  	} else
  		spin_unlock(&ino->i_lock);
  }
  
  void pnfs_roc_set_barrier(struct inode *ino, u32 barrier)
  {
  	struct pnfs_layout_hdr *lo;
  
  	spin_lock(&ino->i_lock);
  	lo = NFS_I(ino)->layout;
  	if (pnfs_seqid_is_newer(barrier, lo->plh_barrier))
  		lo->plh_barrier = barrier;
  	spin_unlock(&ino->i_lock);
  }
  
  bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
  {
  	struct nfs_inode *nfsi = NFS_I(ino);
  	struct pnfs_layout_hdr *lo;
  	struct pnfs_layout_segment *lseg;
  	u32 current_seqid;
  	bool found = false;
  
  	spin_lock(&ino->i_lock);
  	list_for_each_entry(lseg, &nfsi->layout->plh_segs, pls_list)
  		if (test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
  			rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
  			found = true;
  			goto out;
  		}
  	lo = nfsi->layout;
  	current_seqid = be32_to_cpu(lo->plh_stateid.seqid);
  
  	/* Since close does not return a layout stateid for use as
  	 * a barrier, we choose the worst-case barrier.
  	 */
  	*barrier = current_seqid + atomic_read(&lo->plh_outstanding);
  out:
  	spin_unlock(&ino->i_lock);
  	return found;
  }
  
  /*
   * Compare two layout segments for sorting into layout cache.
   * We want to preferentially return RW over RO layouts, so ensure those
   * are seen first.
   */
  static s64
  pnfs_lseg_range_cmp(const struct pnfs_layout_range *l1,
  	   const struct pnfs_layout_range *l2)
  {
  	s64 d;
  
  	/* high offset > low offset */
  	d = l1->offset - l2->offset;
  	if (d)
  		return d;
  
  	/* short length > long length */
  	d = l2->length - l1->length;
  	if (d)
  		return d;
  
  	/* read > read/write */
  	return (int)(l1->iomode == IOMODE_READ) - (int)(l2->iomode == IOMODE_READ);
  }
  
  static void
  pnfs_layout_insert_lseg(struct pnfs_layout_hdr *lo,
  		   struct pnfs_layout_segment *lseg)
  {
  	struct pnfs_layout_segment *lp;
  
  	dprintk("%s:Begin\n", __func__);
  
  	list_for_each_entry(lp, &lo->plh_segs, pls_list) {
  		if (pnfs_lseg_range_cmp(&lseg->pls_range, &lp->pls_range) > 0)
  			continue;
  		list_add_tail(&lseg->pls_list, &lp->pls_list);
  		dprintk("%s: inserted lseg %p "
  			"iomode %d offset %llu length %llu before "
  			"lp %p iomode %d offset %llu length %llu\n",
  			__func__, lseg, lseg->pls_range.iomode,
  			lseg->pls_range.offset, lseg->pls_range.length,
  			lp, lp->pls_range.iomode, lp->pls_range.offset,
  			lp->pls_range.length);
  		goto out;
  	}
  	list_add_tail(&lseg->pls_list, &lo->plh_segs);
  	dprintk("%s: inserted lseg %p "
  		"iomode %d offset %llu length %llu at tail\n",
  		__func__, lseg, lseg->pls_range.iomode,
  		lseg->pls_range.offset, lseg->pls_range.length);
  out:
  	pnfs_get_layout_hdr(lo);
  
  	dprintk("%s:Return\n", __func__);
  }
  
  static struct pnfs_layout_hdr *
  alloc_init_layout_hdr(struct inode *ino,
  		      struct nfs_open_context *ctx,
  		      gfp_t gfp_flags)
  {
  	struct pnfs_layout_hdr *lo;
  
  	lo = pnfs_alloc_layout_hdr(ino, gfp_flags);
  	if (!lo)
  		return NULL;
  	atomic_set(&lo->plh_refcount, 1);
  	INIT_LIST_HEAD(&lo->plh_layouts);
  	INIT_LIST_HEAD(&lo->plh_segs);
  	INIT_LIST_HEAD(&lo->plh_bulk_destroy);
  	lo->plh_inode = ino;
  	lo->plh_lc_cred = get_rpccred(ctx->cred);
  	return lo;
  }
  
  static struct pnfs_layout_hdr *
  pnfs_find_alloc_layout(struct inode *ino,
  		       struct nfs_open_context *ctx,
  		       gfp_t gfp_flags)
  {
  	struct nfs_inode *nfsi = NFS_I(ino);
  	struct pnfs_layout_hdr *new = NULL;
  
  	dprintk("%s Begin ino=%p layout=%p\n", __func__, ino, nfsi->layout);
  
  	if (nfsi->layout != NULL)
  		goto out_existing;
  	spin_unlock(&ino->i_lock);
  	new = alloc_init_layout_hdr(ino, ctx, gfp_flags);
  	spin_lock(&ino->i_lock);
  
  	if (likely(nfsi->layout == NULL)) {	/* Won the race? */
  		nfsi->layout = new;
  		return new;
  	} else if (new != NULL)
  		pnfs_free_layout_hdr(new);
  out_existing:
  	pnfs_get_layout_hdr(nfsi->layout);
  	return nfsi->layout;
  }
  
  /*
   * iomode matching rules:
   * iomode	lseg	match
   * -----	-----	-----
   * ANY		READ	true
   * ANY		RW	true
   * RW		READ	false
   * RW		RW	true
   * READ		READ	true
   * READ		RW	true
   */
  static bool
  pnfs_lseg_range_match(const struct pnfs_layout_range *ls_range,
  		 const struct pnfs_layout_range *range)
  {
  	struct pnfs_layout_range range1;
  
  	if ((range->iomode == IOMODE_RW &&
  	     ls_range->iomode != IOMODE_RW) ||
  	    !pnfs_lseg_range_intersecting(ls_range, range))
  		return 0;
  
  	/* range1 covers only the first byte in the range */
  	range1 = *range;
  	range1.length = 1;
  	return pnfs_lseg_range_contained(ls_range, &range1);
  }
  
  /*
   * lookup range in layout
   */
  static struct pnfs_layout_segment *
  pnfs_find_lseg(struct pnfs_layout_hdr *lo,
  		struct pnfs_layout_range *range)
  {
  	struct pnfs_layout_segment *lseg, *ret = NULL;
  
  	dprintk("%s:Begin\n", __func__);
  
  	list_for_each_entry(lseg, &lo->plh_segs, pls_list) {
  		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags) &&
  		    pnfs_lseg_range_match(&lseg->pls_range, range)) {
  			ret = pnfs_get_lseg(lseg);
  			break;
  		}
  		if (lseg->pls_range.offset > range->offset)
  			break;
  	}
  
  	dprintk("%s:Return lseg %p ref %d\n",
  		__func__, ret, ret ? atomic_read(&ret->pls_refcount) : 0);
  	return ret;
  }
  
  /*
   * Use mdsthreshold hints set at each OPEN to determine if I/O should go
   * to the MDS or over pNFS
   *
   * The nfs_inode read_io and write_io fields are cumulative counters reset
   * when there are no layout segments. Note that in pnfs_update_layout iomode
   * is set to IOMODE_READ for a READ request, and set to IOMODE_RW for a
   * WRITE request.
   *
   * A return of true means use MDS I/O.
   *
   * From rfc 5661:
   * If a file's size is smaller than the file size threshold, data accesses
   * SHOULD be sent to the metadata server.  If an I/O request has a length that
   * is below the I/O size threshold, the I/O SHOULD be sent to the metadata
   * server.  If both file size and I/O size are provided, the client SHOULD
   * reach or exceed  both thresholds before sending its read or write
   * requests to the data server.
   */
  static bool pnfs_within_mdsthreshold(struct nfs_open_context *ctx,
  				     struct inode *ino, int iomode)
  {
  	struct nfs4_threshold *t = ctx->mdsthreshold;
  	struct nfs_inode *nfsi = NFS_I(ino);
  	loff_t fsize = i_size_read(ino);
  	bool size = false, size_set = false, io = false, io_set = false, ret = false;
  
  	if (t == NULL)
  		return ret;
  
  	dprintk("%s bm=0x%x rd_sz=%llu wr_sz=%llu rd_io=%llu wr_io=%llu\n",
  		__func__, t->bm, t->rd_sz, t->wr_sz, t->rd_io_sz, t->wr_io_sz);
  
  	switch (iomode) {
  	case IOMODE_READ:
  		if (t->bm & THRESHOLD_RD) {
  			dprintk("%s fsize %llu\n", __func__, fsize);
  			size_set = true;
  			if (fsize < t->rd_sz)
  				size = true;
  		}
  		if (t->bm & THRESHOLD_RD_IO) {
  			dprintk("%s nfsi->read_io %llu\n", __func__,
  				nfsi->read_io);
  			io_set = true;
  			if (nfsi->read_io < t->rd_io_sz)
  				io = true;
  		}
  		break;
  	case IOMODE_RW:
  		if (t->bm & THRESHOLD_WR) {
  			dprintk("%s fsize %llu\n", __func__, fsize);
  			size_set = true;
  			if (fsize < t->wr_sz)
  				size = true;
  		}
  		if (t->bm & THRESHOLD_WR_IO) {
  			dprintk("%s nfsi->write_io %llu\n", __func__,
  				nfsi->write_io);
  			io_set = true;
  			if (nfsi->write_io < t->wr_io_sz)
  				io = true;
  		}
  		break;
  	}
  	if (size_set && io_set) {
  		if (size && io)
  			ret = true;
  	} else if (size || io)
  		ret = true;
  
  	dprintk("<-- %s size %d io %d ret %d\n", __func__, size, io, ret);
  	return ret;
  }
  
  /*
   * Layout segment is retreived from the server if not cached.
   * The appropriate layout segment is referenced and returned to the caller.
   */
  struct pnfs_layout_segment *
  pnfs_update_layout(struct inode *ino,
  		   struct nfs_open_context *ctx,
  		   loff_t pos,
  		   u64 count,
  		   enum pnfs_iomode iomode,
  		   gfp_t gfp_flags)
  {
  	struct pnfs_layout_range arg = {
  		.iomode = iomode,
  		.offset = pos,
  		.length = count,
  	};
  	unsigned pg_offset;
  	struct nfs_server *server = NFS_SERVER(ino);
  	struct nfs_client *clp = server->nfs_client;
  	struct pnfs_layout_hdr *lo;
  	struct pnfs_layout_segment *lseg = NULL;
  	bool first;
  
  	if (!pnfs_enabled_sb(NFS_SERVER(ino)))
  		goto out;
  
  	if (pnfs_within_mdsthreshold(ctx, ino, iomode))
  		goto out;
  
  	spin_lock(&ino->i_lock);
  	lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
  	if (lo == NULL) {
  		spin_unlock(&ino->i_lock);
  		goto out;
  	}
  
  	/* Do we even need to bother with this? */
  	if (test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
  		dprintk("%s matches recall, use MDS\n", __func__);
  		goto out_unlock;
  	}
  
  	/* if LAYOUTGET already failed once we don't try again */
  	if (pnfs_layout_io_test_failed(lo, iomode))
  		goto out_unlock;
  
  	/* Check to see if the layout for the given range already exists */
  	lseg = pnfs_find_lseg(lo, &arg);
  	if (lseg)
  		goto out_unlock;
  
  	if (pnfs_layoutgets_blocked(lo, 0))
  		goto out_unlock;
  	atomic_inc(&lo->plh_outstanding);
  
  	first = list_empty(&lo->plh_layouts) ? true : false;
  	spin_unlock(&ino->i_lock);
  
  	if (first) {
  		/* The lo must be on the clp list if there is any
  		 * chance of a CB_LAYOUTRECALL(FILE) coming in.
  		 */
  		spin_lock(&clp->cl_lock);
  		list_add_tail(&lo->plh_layouts, &server->layouts);
  		spin_unlock(&clp->cl_lock);
  	}
  
  	pg_offset = arg.offset & ~PAGE_CACHE_MASK;
  	if (pg_offset) {
  		arg.offset -= pg_offset;
  		arg.length += pg_offset;
  	}
  	if (arg.length != NFS4_MAX_UINT64)
  		arg.length = PAGE_CACHE_ALIGN(arg.length);
  
  	lseg = send_layoutget(lo, ctx, &arg, gfp_flags);
  	atomic_dec(&lo->plh_outstanding);
  out_put_layout_hdr:
  	pnfs_put_layout_hdr(lo);
  out:
  	dprintk("%s: inode %s/%llu pNFS layout segment %s for "
  			"(%s, offset: %llu, length: %llu)\n",
  			__func__, ino->i_sb->s_id,
  			(unsigned long long)NFS_FILEID(ino),
  			lseg == NULL ? "not found" : "found",
  			iomode==IOMODE_RW ?  "read/write" : "read-only",
  			(unsigned long long)pos,
  			(unsigned long long)count);
  	return lseg;
  out_unlock:
  	spin_unlock(&ino->i_lock);
  	goto out_put_layout_hdr;
  }
  EXPORT_SYMBOL_GPL(pnfs_update_layout);
  
  struct pnfs_layout_segment *
  pnfs_layout_process(struct nfs4_layoutget *lgp)
  {
  	struct pnfs_layout_hdr *lo = NFS_I(lgp->args.inode)->layout;
  	struct nfs4_layoutget_res *res = &lgp->res;
  	struct pnfs_layout_segment *lseg;
  	struct inode *ino = lo->plh_inode;
  	LIST_HEAD(free_me);
  	int status = 0;
  
  	/* Inject layout blob into I/O device driver */
  	lseg = NFS_SERVER(ino)->pnfs_curr_ld->alloc_lseg(lo, res, lgp->gfp_flags);
  	if (!lseg || IS_ERR(lseg)) {
  		if (!lseg)
  			status = -ENOMEM;
  		else
  			status = PTR_ERR(lseg);
  		dprintk("%s: Could not allocate layout: error %d\n",
  		       __func__, status);
  		goto out;
  	}
  
  	init_lseg(lo, lseg);
  	lseg->pls_range = res->range;
  
  	spin_lock(&ino->i_lock);
  	if (test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
  		dprintk("%s forget reply due to recall\n", __func__);
  		goto out_forget_reply;
  	}
  
  	if (pnfs_layoutgets_blocked(lo, 1)) {
  		dprintk("%s forget reply due to state\n", __func__);
  		goto out_forget_reply;
  	}
  
  	if (nfs4_stateid_match_other(&lo->plh_stateid, &res->stateid)) {
  		/* existing state ID, make sure the sequence number matches. */
  		if (pnfs_layout_stateid_blocked(lo, &res->stateid)) {
  			dprintk("%s forget reply due to sequence\n", __func__);
  			goto out_forget_reply;
  		}
  		pnfs_set_layout_stateid(lo, &res->stateid, false);
  	} else {
  		/*
  		 * We got an entirely new state ID.  Mark all segments for the
  		 * inode invalid, and don't bother validating the stateid
  		 * sequence number.
  		 */
  		pnfs_mark_matching_lsegs_invalid(lo, &free_me, NULL);
  
  		nfs4_stateid_copy(&lo->plh_stateid, &res->stateid);
  		lo->plh_barrier = be32_to_cpu(res->stateid.seqid);
  	}
  
  	clear_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
  
  	pnfs_get_lseg(lseg);
  	pnfs_layout_insert_lseg(lo, lseg);
  
  	if (res->return_on_close) {
  		set_bit(NFS_LSEG_ROC, &lseg->pls_flags);
  		set_bit(NFS_LAYOUT_ROC, &lo->plh_flags);
  	}
  
  	spin_unlock(&ino->i_lock);
  	pnfs_free_lseg_list(&free_me);
  	return lseg;
  out:
  	return ERR_PTR(status);
  
  out_forget_reply:
  	spin_unlock(&ino->i_lock);
  	lseg->pls_layout = lo;
  	NFS_SERVER(ino)->pnfs_curr_ld->free_lseg(lseg);
  	goto out;
  }
  
  void
  pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
  {
  	u64 rd_size = req->wb_bytes;
  
  	if (pgio->pg_lseg == NULL) {
  		if (pgio->pg_dreq == NULL)
  			rd_size = i_size_read(pgio->pg_inode) - req_offset(req);
  		else
  			rd_size = nfs_dreq_bytes_left(pgio->pg_dreq);
  
  		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
  						   req->wb_context,
  						   req_offset(req),
  						   rd_size,
  						   IOMODE_READ,
  						   GFP_KERNEL);
  	}
  	/* If no lseg, fall back to read through mds */
  	if (pgio->pg_lseg == NULL)
  		nfs_pageio_reset_read_mds(pgio);
  
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_read);
  
  void
  pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,
  			   struct nfs_page *req, u64 wb_size)
  {
  	if (pgio->pg_lseg == NULL)
  		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
  						   req->wb_context,
  						   req_offset(req),
  						   wb_size,
  						   IOMODE_RW,
  						   GFP_NOFS);
  	/* If no lseg, fall back to write through mds */
  	if (pgio->pg_lseg == NULL)
  		nfs_pageio_reset_write_mds(pgio);
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_write);
  
  /*
   * Return 0 if @req cannot be coalesced into @pgio, otherwise return the number
   * of bytes (maximum @req->wb_bytes) that can be coalesced.
   */
  size_t
  pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
  		     struct nfs_page *req)
  {
  	unsigned int size;
  	u64 seg_end, req_start, seg_left;
  
  	size = nfs_generic_pg_test(pgio, prev, req);
  	if (!size)
  		return 0;
  
  	/*
  	 * 'size' contains the number of bytes left in the current page (up
  	 * to the original size asked for in @req->wb_bytes).
  	 *
  	 * Calculate how many bytes are left in the layout segment
  	 * and if there are less bytes than 'size', return that instead.
  	 *
  	 * Please also note that 'end_offset' is actually the offset of the
  	 * first byte that lies outside the pnfs_layout_range. FIXME?
  	 *
  	 */
  	if (pgio->pg_lseg) {
  		seg_end = end_offset(pgio->pg_lseg->pls_range.offset,
  				     pgio->pg_lseg->pls_range.length);
  		req_start = req_offset(req);
  		WARN_ON_ONCE(req_start > seg_end);
  		/* start of request is past the last byte of this segment */
  		if (req_start >= seg_end)
  			return 0;
  
  		/* adjust 'size' iff there are fewer bytes left in the
  		 * segment than what nfs_generic_pg_test returned */
  		seg_left = seg_end - req_start;
  		if (seg_left < size)
  			size = (unsigned int)seg_left;
  	}
  
  	return size;
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);
  
  int pnfs_write_done_resend_to_mds(struct nfs_pgio_header *hdr)
  {
  	struct nfs_pageio_descriptor pgio;
  
  	/* Resend all requests through the MDS */
  	nfs_pageio_init_write(&pgio, hdr->inode, FLUSH_STABLE, true,
  			      hdr->completion_ops);
  	set_bit(NFS_CONTEXT_RESEND_WRITES, &hdr->args.context->flags);
  	return nfs_pageio_resend(&pgio, hdr);
  }
  EXPORT_SYMBOL_GPL(pnfs_write_done_resend_to_mds);
  
  static void pnfs_ld_handle_write_error(struct nfs_pgio_header *hdr)
  {
  
  	dprintk("pnfs write error = %d\n", hdr->pnfs_error);
  	if (NFS_SERVER(hdr->inode)->pnfs_curr_ld->flags &
  	    PNFS_LAYOUTRET_ON_ERROR) {
  		pnfs_return_layout(hdr->inode);
  	}
  	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags))
  		hdr->task.tk_status = pnfs_write_done_resend_to_mds(hdr);
  }
  
  /*
   * Called by non rpc-based layout drivers
   */
  void pnfs_ld_write_done(struct nfs_pgio_header *hdr)
  {
  	trace_nfs4_pnfs_write(hdr, hdr->pnfs_error);
  	if (!hdr->pnfs_error) {
  		pnfs_set_layoutcommit(hdr);
  		hdr->mds_ops->rpc_call_done(&hdr->task, hdr);
  	} else
  		pnfs_ld_handle_write_error(hdr);
  	hdr->mds_ops->rpc_release(hdr);
  }
  EXPORT_SYMBOL_GPL(pnfs_ld_write_done);
  
  static void
  pnfs_write_through_mds(struct nfs_pageio_descriptor *desc,
  		struct nfs_pgio_header *hdr)
  {
  	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
  		list_splice_tail_init(&hdr->pages, &desc->pg_list);
  		nfs_pageio_reset_write_mds(desc);
  		desc->pg_recoalesce = 1;
  	}
  	nfs_pgio_data_destroy(hdr);
  	hdr->release(hdr);
  }
  
  static enum pnfs_try_status
  pnfs_try_to_write_data(struct nfs_pgio_header *hdr,
  			const struct rpc_call_ops *call_ops,
  			struct pnfs_layout_segment *lseg,
  			int how)
  {
  	struct inode *inode = hdr->inode;
  	enum pnfs_try_status trypnfs;
  	struct nfs_server *nfss = NFS_SERVER(inode);
  
  	hdr->mds_ops = call_ops;
  
  	dprintk("%s: Writing ino:%lu %u@%llu (how %d)\n", __func__,
  		inode->i_ino, hdr->args.count, hdr->args.offset, how);
  	trypnfs = nfss->pnfs_curr_ld->write_pagelist(hdr, how);
  	if (trypnfs != PNFS_NOT_ATTEMPTED)
  		nfs_inc_stats(inode, NFSIOS_PNFS_WRITE);
  	dprintk("%s End (trypnfs:%d)\n", __func__, trypnfs);
  	return trypnfs;
  }
  
  static void
  pnfs_do_write(struct nfs_pageio_descriptor *desc,
  	      struct nfs_pgio_header *hdr, int how)
  {
  	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
  	struct pnfs_layout_segment *lseg = desc->pg_lseg;
  	enum pnfs_try_status trypnfs;
  
  	desc->pg_lseg = NULL;
  	trypnfs = pnfs_try_to_write_data(hdr, call_ops, lseg, how);
  	if (trypnfs == PNFS_NOT_ATTEMPTED)
  		pnfs_write_through_mds(desc, hdr);
  	pnfs_put_lseg(lseg);
  }
  
  static void pnfs_writehdr_free(struct nfs_pgio_header *hdr)
  {
  	pnfs_put_lseg(hdr->lseg);
  	nfs_pgio_header_free(hdr);
  }
  EXPORT_SYMBOL_GPL(pnfs_writehdr_free);
  
  int
  pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
  {
  	struct nfs_pgio_header *hdr;
  	int ret;
  
  	hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
  	if (!hdr) {
  		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
  		pnfs_put_lseg(desc->pg_lseg);
  		desc->pg_lseg = NULL;
  		return -ENOMEM;
  	}
  	nfs_pgheader_init(desc, hdr, pnfs_writehdr_free);
  	hdr->lseg = pnfs_get_lseg(desc->pg_lseg);
  	ret = nfs_generic_pgio(desc, hdr);
  	if (ret != 0) {
  		pnfs_put_lseg(desc->pg_lseg);
  		desc->pg_lseg = NULL;
  	} else
  		pnfs_do_write(desc, hdr, desc->pg_ioflags);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_pg_writepages);
  
  int pnfs_read_done_resend_to_mds(struct nfs_pgio_header *hdr)
  {
  	struct nfs_pageio_descriptor pgio;
  
  	/* Resend all requests through the MDS */
  	nfs_pageio_init_read(&pgio, hdr->inode, true, hdr->completion_ops);
  	return nfs_pageio_resend(&pgio, hdr);
  }
  EXPORT_SYMBOL_GPL(pnfs_read_done_resend_to_mds);
  
  static void pnfs_ld_handle_read_error(struct nfs_pgio_header *hdr)
  {
  	dprintk("pnfs read error = %d\n", hdr->pnfs_error);
  	if (NFS_SERVER(hdr->inode)->pnfs_curr_ld->flags &
  	    PNFS_LAYOUTRET_ON_ERROR) {
  		pnfs_return_layout(hdr->inode);
  	}
  	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags))
  		hdr->task.tk_status = pnfs_read_done_resend_to_mds(hdr);
  }
  
  /*
   * Called by non rpc-based layout drivers
   */
  void pnfs_ld_read_done(struct nfs_pgio_header *hdr)
  {
  	trace_nfs4_pnfs_read(hdr, hdr->pnfs_error);
  	if (likely(!hdr->pnfs_error)) {
  		__nfs4_read_done_cb(hdr);
  		hdr->mds_ops->rpc_call_done(&hdr->task, hdr);
  	} else
  		pnfs_ld_handle_read_error(hdr);
  	hdr->mds_ops->rpc_release(hdr);
  }
  EXPORT_SYMBOL_GPL(pnfs_ld_read_done);
  
  static void
  pnfs_read_through_mds(struct nfs_pageio_descriptor *desc,
  		struct nfs_pgio_header *hdr)
  {
  	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
  		list_splice_tail_init(&hdr->pages, &desc->pg_list);
  		nfs_pageio_reset_read_mds(desc);
  		desc->pg_recoalesce = 1;
  	}
  	nfs_pgio_data_destroy(hdr);
  	hdr->release(hdr);
  }
  
  /*
   * Call the appropriate parallel I/O subsystem read function.
   */
  static enum pnfs_try_status
  pnfs_try_to_read_data(struct nfs_pgio_header *hdr,
  		       const struct rpc_call_ops *call_ops,
  		       struct pnfs_layout_segment *lseg)
  {
  	struct inode *inode = hdr->inode;
  	struct nfs_server *nfss = NFS_SERVER(inode);
  	enum pnfs_try_status trypnfs;
  
  	hdr->mds_ops = call_ops;
  
  	dprintk("%s: Reading ino:%lu %u@%llu\n",
  		__func__, inode->i_ino, hdr->args.count, hdr->args.offset);
  
  	trypnfs = nfss->pnfs_curr_ld->read_pagelist(hdr);
  	if (trypnfs != PNFS_NOT_ATTEMPTED)
  		nfs_inc_stats(inode, NFSIOS_PNFS_READ);
  	dprintk("%s End (trypnfs:%d)\n", __func__, trypnfs);
  	return trypnfs;
  }
  
  static void
  pnfs_do_read(struct nfs_pageio_descriptor *desc, struct nfs_pgio_header *hdr)
  {
  	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
  	struct pnfs_layout_segment *lseg = desc->pg_lseg;
  	enum pnfs_try_status trypnfs;
  
  	desc->pg_lseg = NULL;
  	trypnfs = pnfs_try_to_read_data(hdr, call_ops, lseg);
  	if (trypnfs == PNFS_NOT_ATTEMPTED)
  		pnfs_read_through_mds(desc, hdr);
  	pnfs_put_lseg(lseg);
  }
  
  static void pnfs_readhdr_free(struct nfs_pgio_header *hdr)
  {
  	pnfs_put_lseg(hdr->lseg);
  	nfs_pgio_header_free(hdr);
  }
  EXPORT_SYMBOL_GPL(pnfs_readhdr_free);
  
  int
  pnfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
  {
  	struct nfs_pgio_header *hdr;
  	int ret;
  
  	hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
  	if (!hdr) {
  		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
  		ret = -ENOMEM;
  		pnfs_put_lseg(desc->pg_lseg);
  		desc->pg_lseg = NULL;
  		return ret;
  	}
  	nfs_pgheader_init(desc, hdr, pnfs_readhdr_free);
  	hdr->lseg = pnfs_get_lseg(desc->pg_lseg);
  	ret = nfs_generic_pgio(desc, hdr);
  	if (ret != 0) {
  		pnfs_put_lseg(desc->pg_lseg);
  		desc->pg_lseg = NULL;
  	} else
  		pnfs_do_read(desc, hdr);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(pnfs_generic_pg_readpages);
  
  static void pnfs_clear_layoutcommitting(struct inode *inode)
  {
  	unsigned long *bitlock = &NFS_I(inode)->flags;
  
  	clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);
  	smp_mb__after_atomic();
  	wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);
  }
  
  /*
   * There can be multiple RW segments.
   */
  static void pnfs_list_write_lseg(struct inode *inode, struct list_head *listp)
  {
  	struct pnfs_layout_segment *lseg;
  
  	list_for_each_entry(lseg, &NFS_I(inode)->layout->plh_segs, pls_list) {
  		if (lseg->pls_range.iomode == IOMODE_RW &&
  		    test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
  			list_add(&lseg->pls_lc_list, listp);
  	}
  }
  
  static void pnfs_list_write_lseg_done(struct inode *inode, struct list_head *listp)
  {
  	struct pnfs_layout_segment *lseg, *tmp;
  
  	/* Matched by references in pnfs_set_layoutcommit */
  	list_for_each_entry_safe(lseg, tmp, listp, pls_lc_list) {
  		list_del_init(&lseg->pls_lc_list);
  		pnfs_put_lseg(lseg);
  	}
  
  	pnfs_clear_layoutcommitting(inode);
  }
  
  void pnfs_set_lo_fail(struct pnfs_layout_segment *lseg)
  {
  	pnfs_layout_io_set_failed(lseg->pls_layout, lseg->pls_range.iomode);
  }
  EXPORT_SYMBOL_GPL(pnfs_set_lo_fail);
  
  void
  pnfs_set_layoutcommit(struct nfs_pgio_header *hdr)
  {
  	struct inode *inode = hdr->inode;
  	struct nfs_inode *nfsi = NFS_I(inode);
  	loff_t end_pos = hdr->mds_offset + hdr->res.count;
  	bool mark_as_dirty = false;
  
  	spin_lock(&inode->i_lock);
  	if (!test_and_set_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) {
  		mark_as_dirty = true;
  		dprintk("%s: Set layoutcommit for inode %lu ",
  			__func__, inode->i_ino);
  	}
  	if (!test_and_set_bit(NFS_LSEG_LAYOUTCOMMIT, &hdr->lseg->pls_flags)) {
  		/* references matched in nfs4_layoutcommit_release */
  		pnfs_get_lseg(hdr->lseg);
  	}
  	if (end_pos > nfsi->layout->plh_lwb)
  		nfsi->layout->plh_lwb = end_pos;
  	spin_unlock(&inode->i_lock);
  	dprintk("%s: lseg %p end_pos %llu\n",
  		__func__, hdr->lseg, nfsi->layout->plh_lwb);
  
  	/* if pnfs_layoutcommit_inode() runs between inode locks, the next one
  	 * will be a noop because NFS_INO_LAYOUTCOMMIT will not be set */
  	if (mark_as_dirty)
  		mark_inode_dirty_sync(inode);
  }
  EXPORT_SYMBOL_GPL(pnfs_set_layoutcommit);
  
  void pnfs_commit_set_layoutcommit(struct nfs_commit_data *data)
  {
  	struct inode *inode = data->inode;
  	struct nfs_inode *nfsi = NFS_I(inode);
  	bool mark_as_dirty = false;
  
  	spin_lock(&inode->i_lock);
  	if (!test_and_set_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) {
  		mark_as_dirty = true;
  		dprintk("%s: Set layoutcommit for inode %lu ",
  			__func__, inode->i_ino);
  	}
  	if (!test_and_set_bit(NFS_LSEG_LAYOUTCOMMIT, &data->lseg->pls_flags)) {
  		/* references matched in nfs4_layoutcommit_release */
  		pnfs_get_lseg(data->lseg);
  	}
  	if (data->lwb > nfsi->layout->plh_lwb)
  		nfsi->layout->plh_lwb = data->lwb;
  	spin_unlock(&inode->i_lock);
  	dprintk("%s: lseg %p end_pos %llu\n",
  		__func__, data->lseg, nfsi->layout->plh_lwb);
  
  	/* if pnfs_layoutcommit_inode() runs between inode locks, the next one
  	 * will be a noop because NFS_INO_LAYOUTCOMMIT will not be set */
  	if (mark_as_dirty)
  		mark_inode_dirty_sync(inode);
  }
  EXPORT_SYMBOL_GPL(pnfs_commit_set_layoutcommit);
  
  void pnfs_cleanup_layoutcommit(struct nfs4_layoutcommit_data *data)
  {
  	struct nfs_server *nfss = NFS_SERVER(data->args.inode);
  
  	if (nfss->pnfs_curr_ld->cleanup_layoutcommit)
  		nfss->pnfs_curr_ld->cleanup_layoutcommit(data);
  	pnfs_list_write_lseg_done(data->args.inode, &data->lseg_list);
  }
  
  /*
   * For the LAYOUT4_NFSV4_1_FILES layout type, NFS_DATA_SYNC WRITEs and
   * NFS_UNSTABLE WRITEs with a COMMIT to data servers must store enough
   * data to disk to allow the server to recover the data if it crashes.
   * LAYOUTCOMMIT is only needed when the NFL4_UFLG_COMMIT_THRU_MDS flag
   * is off, and a COMMIT is sent to a data server, or
   * if WRITEs to a data server return NFS_DATA_SYNC.
   */
  int
  pnfs_layoutcommit_inode(struct inode *inode, bool sync)
  {
  	struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;
  	struct nfs4_layoutcommit_data *data;
  	struct nfs_inode *nfsi = NFS_I(inode);
  	loff_t end_pos;
  	int status;
  
  	if (!pnfs_layoutcommit_outstanding(inode))
  		return 0;
  
  	dprintk("--> %s inode %lu\n", __func__, inode->i_ino);
  
  	status = -EAGAIN;
  	if (test_and_set_bit(NFS_INO_LAYOUTCOMMITTING, &nfsi->flags)) {
  		if (!sync)
  			goto out;
  		status = wait_on_bit_lock_action(&nfsi->flags,
  				NFS_INO_LAYOUTCOMMITTING,
  				nfs_wait_bit_killable,
  				TASK_KILLABLE);
  		if (status)
  			goto out;
  	}
  
  	status = -ENOMEM;
  	/* Note kzalloc ensures data->res.seq_res.sr_slot == NULL */
  	data = kzalloc(sizeof(*data), GFP_NOFS);
  	if (!data)
  		goto clear_layoutcommitting;
  
  	status = 0;
  	spin_lock(&inode->i_lock);
  	if (!test_and_clear_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
  		goto out_unlock;
  
  	INIT_LIST_HEAD(&data->lseg_list);
  	pnfs_list_write_lseg(inode, &data->lseg_list);
  
  	end_pos = nfsi->layout->plh_lwb;
  	nfsi->layout->plh_lwb = 0;
  
  	nfs4_stateid_copy(&data->args.stateid, &nfsi->layout->plh_stateid);
  	spin_unlock(&inode->i_lock);
  
  	data->args.inode = inode;
  	data->cred = get_rpccred(nfsi->layout->plh_lc_cred);
  	nfs_fattr_init(&data->fattr);
  	data->args.bitmask = NFS_SERVER(inode)->cache_consistency_bitmask;
  	data->res.fattr = &data->fattr;
  	data->args.lastbytewritten = end_pos - 1;
  	data->res.server = NFS_SERVER(inode);
  
  	if (ld->prepare_layoutcommit) {
  		status = ld->prepare_layoutcommit(&data->args);
  		if (status) {
  			spin_lock(&inode->i_lock);
  			if (end_pos < nfsi->layout->plh_lwb)
  				nfsi->layout->plh_lwb = end_pos;
  			spin_unlock(&inode->i_lock);
  			put_rpccred(data->cred);
  			set_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags);
  			goto clear_layoutcommitting;
  		}
  	}
  
  
  	status = nfs4_proc_layoutcommit(data, sync);
  out:
  	if (status)
  		mark_inode_dirty_sync(inode);
  	dprintk("<-- %s status %d\n", __func__, status);
  	return status;
  out_unlock:
  	spin_unlock(&inode->i_lock);
  	kfree(data);
  clear_layoutcommitting:
  	pnfs_clear_layoutcommitting(inode);
  	goto out;
  }
  
  struct nfs4_threshold *pnfs_mdsthreshold_alloc(void)
  {
  	struct nfs4_threshold *thp;
  
  	thp = kzalloc(sizeof(*thp), GFP_NOFS);
  	if (!thp) {
  		dprintk("%s mdsthreshold allocation failed\n", __func__);
  		return NULL;
  	}
  	return thp;
  }
  