text: /*
   * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
   * Copyright (C) 2004 - 2006 Red Hat, Inc. All rights reserved.
   *
   * This file is released under the GPL.
   */
  
  #include "dm-core.h"
  
  #include <linux/module.h>
  #include <linux/vmalloc.h>
  #include <linux/miscdevice.h>
  #include <linux/init.h>
  #include <linux/wait.h>
  #include <linux/slab.h>
  #include <linux/dm-ioctl.h>
  #include <linux/hdreg.h>
  #include <linux/compat.h>
  
  #include <asm/uaccess.h>
  
  #define DM_MSG_PREFIX "ioctl"
  #define DM_DRIVER_EMAIL "dm-devel@redhat.com"
  
  /*-----------------------------------------------------------------
   * The ioctl interface needs to be able to look up devices by
   * name or uuid.
   *---------------------------------------------------------------*/
  struct hash_cell {
  	struct list_head name_list;
  	struct list_head uuid_list;
  
  	char *name;
  	char *uuid;
  	struct mapped_device *md;
  	struct dm_table *new_map;
  };
  
  /*
   * A dummy definition to make RCU happy.
   * struct dm_table should never be dereferenced in this file.
   */
  struct dm_table {
  	int undefined__;
  };
  
  struct vers_iter {
      size_t param_size;
      struct dm_target_versions *vers, *old_vers;
      char *end;
      uint32_t flags;
  };
  
  
  #define NUM_BUCKETS 64
  #define MASK_BUCKETS (NUM_BUCKETS - 1)
  static struct list_head _name_buckets[NUM_BUCKETS];
  static struct list_head _uuid_buckets[NUM_BUCKETS];
  
  static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred);
  
  /*
   * Guards access to both hash tables.
   */
  static DECLARE_RWSEM(_hash_lock);
  
  /*
   * Protects use of mdptr to obtain hash cell name and uuid from mapped device.
   */
  static DEFINE_MUTEX(dm_hash_cells_mutex);
  
  static void init_buckets(struct list_head *buckets)
  {
  	unsigned int i;
  
  	for (i = 0; i < NUM_BUCKETS; i++)
  		INIT_LIST_HEAD(buckets + i);
  }
  
  static int dm_hash_init(void)
  {
  	init_buckets(_name_buckets);
  	init_buckets(_uuid_buckets);
  	return 0;
  }
  
  static void dm_hash_exit(void)
  {
  	dm_hash_remove_all(false, false, false);
  }
  
  /*-----------------------------------------------------------------
   * Hash function:
   * We're not really concerned with the str hash function being
   * fast since it's only used by the ioctl interface.
   *---------------------------------------------------------------*/
  static unsigned int hash_str(const char *str)
  {
  	const unsigned int hash_mult = 2654435387U;
  	unsigned int h = 0;
  
  	while (*str)
  		h = (h + (unsigned int) *str++) * hash_mult;
  
  	return h & MASK_BUCKETS;
  }
  
  /*-----------------------------------------------------------------
   * Code for looking up a device by name
   *---------------------------------------------------------------*/
  static struct hash_cell *__get_name_cell(const char *str)
  {
  	struct hash_cell *hc;
  	unsigned int h = hash_str(str);
  
  	list_for_each_entry (hc, _name_buckets + h, name_list)
  		if (!strcmp(hc->name, str)) {
  			dm_get(hc->md);
  			return hc;
  		}
  
  	return NULL;
  }
  
  static struct hash_cell *__get_uuid_cell(const char *str)
  {
  	struct hash_cell *hc;
  	unsigned int h = hash_str(str);
  
  	list_for_each_entry (hc, _uuid_buckets + h, uuid_list)
  		if (!strcmp(hc->uuid, str)) {
  			dm_get(hc->md);
  			return hc;
  		}
  
  	return NULL;
  }
  
  static struct hash_cell *__get_dev_cell(uint64_t dev)
  {
  	struct mapped_device *md;
  	struct hash_cell *hc;
  
  	md = dm_get_md(huge_decode_dev(dev));
  	if (!md)
  		return NULL;
  
  	hc = dm_get_mdptr(md);
  	if (!hc) {
  		dm_put(md);
  		return NULL;
  	}
  
  	return hc;
  }
  
  /*-----------------------------------------------------------------
   * Inserting, removing and renaming a device.
   *---------------------------------------------------------------*/
  static struct hash_cell *alloc_cell(const char *name, const char *uuid,
  				    struct mapped_device *md)
  {
  	struct hash_cell *hc;
  
  	hc = kmalloc(sizeof(*hc), GFP_KERNEL);
  	if (!hc)
  		return NULL;
  
  	hc->name = kstrdup(name, GFP_KERNEL);
  	if (!hc->name) {
  		kfree(hc);
  		return NULL;
  	}
  
  	if (!uuid)
  		hc->uuid = NULL;
  
  	else {
  		hc->uuid = kstrdup(uuid, GFP_KERNEL);
  		if (!hc->uuid) {
  			kfree(hc->name);
  			kfree(hc);
  			return NULL;
  		}
  	}
  
  	INIT_LIST_HEAD(&hc->name_list);
  	INIT_LIST_HEAD(&hc->uuid_list);
  	hc->md = md;
  	hc->new_map = NULL;
  	return hc;
  }
  
  static void free_cell(struct hash_cell *hc)
  {
  	if (hc) {
  		kfree(hc->name);
  		kfree(hc->uuid);
  		kfree(hc);
  	}
  }
  
  /*
   * The kdev_t and uuid of a device can never change once it is
   * initially inserted.
   */
  static int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
  {
  	struct hash_cell *cell, *hc;
  
  	/*
  	 * Allocate the new cells.
  	 */
  	cell = alloc_cell(name, uuid, md);
  	if (!cell)
  		return -ENOMEM;
  
  	/*
  	 * Insert the cell into both hash tables.
  	 */
  	down_write(&_hash_lock);
  	hc = __get_name_cell(name);
  	if (hc) {
  		dm_put(hc->md);
  		goto bad;
  	}
  
  	list_add(&cell->name_list, _name_buckets + hash_str(name));
  
  	if (uuid) {
  		hc = __get_uuid_cell(uuid);
  		if (hc) {
  			list_del(&cell->name_list);
  			dm_put(hc->md);
  			goto bad;
  		}
  		list_add(&cell->uuid_list, _uuid_buckets + hash_str(uuid));
  	}
  	dm_get(md);
  	mutex_lock(&dm_hash_cells_mutex);
  	dm_set_mdptr(md, cell);
  	mutex_unlock(&dm_hash_cells_mutex);
  	up_write(&_hash_lock);
  
  	return 0;
  
   bad:
  	up_write(&_hash_lock);
  	free_cell(cell);
  	return -EBUSY;
  }
  
  static struct dm_table *__hash_remove(struct hash_cell *hc)
  {
  	struct dm_table *table;
  	int srcu_idx;
  
  	/* remove from the dev hash */
  	list_del(&hc->uuid_list);
  	list_del(&hc->name_list);
  	mutex_lock(&dm_hash_cells_mutex);
  	dm_set_mdptr(hc->md, NULL);
  	mutex_unlock(&dm_hash_cells_mutex);
  
  	table = dm_get_live_table(hc->md, &srcu_idx);
  	if (table)
  		dm_table_event(table);
  	dm_put_live_table(hc->md, srcu_idx);
  
  	table = NULL;
  	if (hc->new_map)
  		table = hc->new_map;
  	dm_put(hc->md);
  	free_cell(hc);
  
  	return table;
  }
  
  static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred)
  {
  	int i, dev_skipped;
  	struct hash_cell *hc;
  	struct mapped_device *md;
  	struct dm_table *t;
  
  retry:
  	dev_skipped = 0;
  
  	down_write(&_hash_lock);
  
  	for (i = 0; i < NUM_BUCKETS; i++) {
  		list_for_each_entry(hc, _name_buckets + i, name_list) {
  			md = hc->md;
  			dm_get(md);
  
  			if (keep_open_devices &&
  			    dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
  				dm_put(md);
  				dev_skipped++;
  				continue;
  			}
  
  			t = __hash_remove(hc);
  
  			up_write(&_hash_lock);
  
  			if (t) {
  				dm_sync_table(md);
  				dm_table_destroy(t);
  			}
  			dm_put(md);
  			if (likely(keep_open_devices))
  				dm_destroy(md);
  			else
  				dm_destroy_immediate(md);
  
  			/*
  			 * Some mapped devices may be using other mapped
  			 * devices, so repeat until we make no further
  			 * progress.  If a new mapped device is created
  			 * here it will also get removed.
  			 */
  			goto retry;
  		}
  	}
  
  	up_write(&_hash_lock);
  
  	if (dev_skipped)
  		DMWARN("remove_all left %d open device(s)", dev_skipped);
  }
  
  /*
   * Set the uuid of a hash_cell that isn't already set.
   */
  static void __set_cell_uuid(struct hash_cell *hc, char *new_uuid)
  {
  	mutex_lock(&dm_hash_cells_mutex);
  	hc->uuid = new_uuid;
  	mutex_unlock(&dm_hash_cells_mutex);
  
  	list_add(&hc->uuid_list, _uuid_buckets + hash_str(new_uuid));
  }
  
  /*
   * Changes the name of a hash_cell and returns the old name for
   * the caller to free.
   */
  static char *__change_cell_name(struct hash_cell *hc, char *new_name)
  {
  	char *old_name;
  
  	/*
  	 * Rename and move the name cell.
  	 */
  	list_del(&hc->name_list);
  	old_name = hc->name;
  
  	mutex_lock(&dm_hash_cells_mutex);
  	hc->name = new_name;
  	mutex_unlock(&dm_hash_cells_mutex);
  
  	list_add(&hc->name_list, _name_buckets + hash_str(new_name));
  
  	return old_name;
  }
  
  static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
  					    const char *new)
  {
  	char *new_data, *old_name = NULL;
  	struct hash_cell *hc;
  	struct dm_table *table;
  	struct mapped_device *md;
  	unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
  	int srcu_idx;
  
  	/*
  	 * duplicate new.
  	 */
  	new_data = kstrdup(new, GFP_KERNEL);
  	if (!new_data)
  		return ERR_PTR(-ENOMEM);
  
  	down_write(&_hash_lock);
  
  	/*
  	 * Is new free ?
  	 */
  	if (change_uuid)
  		hc = __get_uuid_cell(new);
  	else
  		hc = __get_name_cell(new);
  
  	if (hc) {
  		DMWARN("Unable to change %s on mapped device %s to one that "
  		       "already exists: %s",
  		       change_uuid ? "uuid" : "name",
  		       param->name, new);
  		dm_put(hc->md);
  		up_write(&_hash_lock);
  		kfree(new_data);
  		return ERR_PTR(-EBUSY);
  	}
  
  	/*
  	 * Is there such a device as 'old' ?
  	 */
  	hc = __get_name_cell(param->name);
  	if (!hc) {
  		DMWARN("Unable to rename non-existent device, %s to %s%s",
  		       param->name, change_uuid ? "uuid " : "", new);
  		up_write(&_hash_lock);
  		kfree(new_data);
  		return ERR_PTR(-ENXIO);
  	}
  
  	/*
  	 * Does this device already have a uuid?
  	 */
  	if (change_uuid && hc->uuid) {
  		DMWARN("Unable to change uuid of mapped device %s to %s "
  		       "because uuid is already set to %s",
  		       param->name, new, hc->uuid);
  		dm_put(hc->md);
  		up_write(&_hash_lock);
  		kfree(new_data);
  		return ERR_PTR(-EINVAL);
  	}
  
  	if (change_uuid)
  		__set_cell_uuid(hc, new_data);
  	else
  		old_name = __change_cell_name(hc, new_data);
  
  	/*
  	 * Wake up any dm event waiters.
  	 */
  	table = dm_get_live_table(hc->md, &srcu_idx);
  	if (table)
  		dm_table_event(table);
  	dm_put_live_table(hc->md, srcu_idx);
  
  	if (!dm_kobject_uevent(hc->md, KOBJ_CHANGE, param->event_nr))
  		param->flags |= DM_UEVENT_GENERATED_FLAG;
  
  	md = hc->md;
  	up_write(&_hash_lock);
  	kfree(old_name);
  
  	return md;
  }
  
  void dm_deferred_remove(void)
  {
  	dm_hash_remove_all(true, false, true);
  }
  
  /*-----------------------------------------------------------------
   * Implementation of the ioctl commands
   *---------------------------------------------------------------*/
  /*
   * All the ioctl commands get dispatched to functions with this
   * prototype.
   */
  typedef int (*ioctl_fn)(struct dm_ioctl *param, size_t param_size);
  
  static int remove_all(struct dm_ioctl *param, size_t param_size)
  {
  	dm_hash_remove_all(true, !!(param->flags & DM_DEFERRED_REMOVE), false);
  	param->data_size = 0;
  	return 0;
  }
  
  /*
   * Round up the ptr to an 8-byte boundary.
   */
  #define ALIGN_MASK 7
  static inline void *align_ptr(void *ptr)
  {
  	return (void *) (((size_t) (ptr + ALIGN_MASK)) & ~ALIGN_MASK);
  }
  
  /*
   * Retrieves the data payload buffer from an already allocated
   * struct dm_ioctl.
   */
  static void *get_result_buffer(struct dm_ioctl *param, size_t param_size,
  			       size_t *len)
  {
  	param->data_start = align_ptr(param + 1) - (void *) param;
  
  	if (param->data_start < param_size)
  		*len = param_size - param->data_start;
  	else
  		*len = 0;
  
  	return ((void *) param) + param->data_start;
  }
  
  static int list_devices(struct dm_ioctl *param, size_t param_size)
  {
  	unsigned int i;
  	struct hash_cell *hc;
  	size_t len, needed = 0;
  	struct gendisk *disk;
  	struct dm_name_list *nl, *old_nl = NULL;
  
  	down_write(&_hash_lock);
  
  	/*
  	 * Loop through all the devices working out how much
  	 * space we need.
  	 */
  	for (i = 0; i < NUM_BUCKETS; i++) {
  		list_for_each_entry (hc, _name_buckets + i, name_list) {
  			needed += sizeof(struct dm_name_list);
  			needed += strlen(hc->name) + 1;
  			needed += ALIGN_MASK;
  		}
  	}
  
  	/*
  	 * Grab our output buffer.
  	 */
  	nl = get_result_buffer(param, param_size, &len);
  	if (len < needed) {
  		param->flags |= DM_BUFFER_FULL_FLAG;
  		goto out;
  	}
  	param->data_size = param->data_start + needed;
  
  	nl->dev = 0;	/* Flags no data */
  
  	/*
  	 * Now loop through filling out the names.
  	 */
  	for (i = 0; i < NUM_BUCKETS; i++) {
  		list_for_each_entry (hc, _name_buckets + i, name_list) {
  			if (old_nl)
  				old_nl->next = (uint32_t) ((void *) nl -
  							   (void *) old_nl);
  			disk = dm_disk(hc->md);
  			nl->dev = huge_encode_dev(disk_devt(disk));
  			nl->next = 0;
  			strcpy(nl->name, hc->name);
  
  			old_nl = nl;
  			nl = align_ptr(((void *) ++nl) + strlen(hc->name) + 1);
  		}
  	}
  
   out:
  	up_write(&_hash_lock);
  	return 0;
  }
  
  static void list_version_get_needed(struct target_type *tt, void *needed_param)
  {
      size_t *needed = needed_param;
  
      *needed += sizeof(struct dm_target_versions);
      *needed += strlen(tt->name);
      *needed += ALIGN_MASK;
  }
  
  static void list_version_get_info(struct target_type *tt, void *param)
  {
      struct vers_iter *info = param;
  
      /* Check space - it might have changed since the first iteration */
      if ((char *)info->vers + sizeof(tt->version) + strlen(tt->name) + 1 >
  	info->end) {
  
  	info->flags = DM_BUFFER_FULL_FLAG;
  	return;
      }
  
      if (info->old_vers)
  	info->old_vers->next = (uint32_t) ((void *)info->vers -
  					   (void *)info->old_vers);
      info->vers->version[0] = tt->version[0];
      info->vers->version[1] = tt->version[1];
      info->vers->version[2] = tt->version[2];
      info->vers->next = 0;
      strcpy(info->vers->name, tt->name);
  
      info->old_vers = info->vers;
      info->vers = align_ptr(((void *) ++info->vers) + strlen(tt->name) + 1);
  }
  
  static int list_versions(struct dm_ioctl *param, size_t param_size)
  {
  	size_t len, needed = 0;
  	struct dm_target_versions *vers;
  	struct vers_iter iter_info;
  
  	/*
  	 * Loop through all the devices working out how much
  	 * space we need.
  	 */
  	dm_target_iterate(list_version_get_needed, &needed);
  
  	/*
  	 * Grab our output buffer.
  	 */
  	vers = get_result_buffer(param, param_size, &len);
  	if (len < needed) {
  		param->flags |= DM_BUFFER_FULL_FLAG;
  		goto out;
  	}
  	param->data_size = param->data_start + needed;
  
  	iter_info.param_size = param_size;
  	iter_info.old_vers = NULL;
  	iter_info.vers = vers;
  	iter_info.flags = 0;
  	iter_info.end = (char *)vers+len;
  
  	/*
  	 * Now loop through filling out the names & versions.
  	 */
  	dm_target_iterate(list_version_get_info, &iter_info);
  	param->flags |= iter_info.flags;
  
   out:
  	return 0;
  }
  
  static int check_name(const char *name)
  {
  	if (strchr(name, '/')) {
  		DMWARN("invalid device name");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  /*
   * On successful return, the caller must not attempt to acquire
   * _hash_lock without first calling dm_put_live_table, because dm_table_destroy
   * waits for this dm_put_live_table and could be called under this lock.
   */
  static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *srcu_idx)
  {
  	struct hash_cell *hc;
  	struct dm_table *table = NULL;
  
  	/* increment rcu count, we don't care about the table pointer */
  	dm_get_live_table(md, srcu_idx);
  
  	down_read(&_hash_lock);
  	hc = dm_get_mdptr(md);
  	if (!hc || hc->md != md) {
  		DMWARN("device has been removed from the dev hash table.");
  		goto out;
  	}
  
  	table = hc->new_map;
  
  out:
  	up_read(&_hash_lock);
  
  	return table;
  }
  
  static struct dm_table *dm_get_live_or_inactive_table(struct mapped_device *md,
  						      struct dm_ioctl *param,
  						      int *srcu_idx)
  {
  	return (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) ?
  		dm_get_inactive_table(md, srcu_idx) : dm_get_live_table(md, srcu_idx);
  }
  
  /*
   * Fills in a dm_ioctl structure, ready for sending back to
   * userland.
   */
  static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
  {
  	struct gendisk *disk = dm_disk(md);
  	struct dm_table *table;
  	int srcu_idx;
  
  	param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
  			  DM_ACTIVE_PRESENT_FLAG | DM_INTERNAL_SUSPEND_FLAG);
  
  	if (dm_suspended_md(md))
  		param->flags |= DM_SUSPEND_FLAG;
  
  	if (dm_suspended_internally_md(md))
  		param->flags |= DM_INTERNAL_SUSPEND_FLAG;
  
  	if (dm_test_deferred_remove_flag(md))
  		param->flags |= DM_DEFERRED_REMOVE;
  
  	param->dev = huge_encode_dev(disk_devt(disk));
  
  	/*
  	 * Yes, this will be out of date by the time it gets back
  	 * to userland, but it is still very useful for
  	 * debugging.
  	 */
  	param->open_count = dm_open_count(md);
  
  	param->event_nr = dm_get_event_nr(md);
  	param->target_count = 0;
  
  	table = dm_get_live_table(md, &srcu_idx);
  	if (table) {
  		if (!(param->flags & DM_QUERY_INACTIVE_TABLE_FLAG)) {
  			if (get_disk_ro(disk))
  				param->flags |= DM_READONLY_FLAG;
  			param->target_count = dm_table_get_num_targets(table);
  		}
  
  		param->flags |= DM_ACTIVE_PRESENT_FLAG;
  	}
  	dm_put_live_table(md, srcu_idx);
  
  	if (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) {
  		int srcu_idx;
  		table = dm_get_inactive_table(md, &srcu_idx);
  		if (table) {
  			if (!(dm_table_get_mode(table) & FMODE_WRITE))
  				param->flags |= DM_READONLY_FLAG;
  			param->target_count = dm_table_get_num_targets(table);
  		}
  		dm_put_live_table(md, srcu_idx);
  	}
  }
  
  static int dev_create(struct dm_ioctl *param, size_t param_size)
  {
  	int r, m = DM_ANY_MINOR;
  	struct mapped_device *md;
  
  	r = check_name(param->name);
  	if (r)
  		return r;
  
  	if (param->flags & DM_PERSISTENT_DEV_FLAG)
  		m = MINOR(huge_decode_dev(param->dev));
  
  	r = dm_create(m, &md);
  	if (r)
  		return r;
  
  	r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
  	if (r) {
  		dm_put(md);
  		dm_destroy(md);
  		return r;
  	}
  
  	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
  
  	__dev_status(md, param);
  
  	dm_put(md);
  
  	return 0;
  }
  
  /*
   * Always use UUID for lookups if it's present, otherwise use name or dev.
   */
  static struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param)
  {
  	struct hash_cell *hc = NULL;
  
  	if (*param->uuid) {
  		if (*param->name || param->dev)
  			return NULL;
  
  		hc = __get_uuid_cell(param->uuid);
  		if (!hc)
  			return NULL;
  	} else if (*param->name) {
  		if (param->dev)
  			return NULL;
  
  		hc = __get_name_cell(param->name);
  		if (!hc)
  			return NULL;
  	} else if (param->dev) {
  		hc = __get_dev_cell(param->dev);
  		if (!hc)
  			return NULL;
  	} else
  		return NULL;
  
  	/*
  	 * Sneakily write in both the name and the uuid
  	 * while we have the cell.
  	 */
  	strlcpy(param->name, hc->name, sizeof(param->name));
  	if (hc->uuid)
  		strlcpy(param->uuid, hc->uuid, sizeof(param->uuid));
  	else
  		param->uuid[0] = '\0';
  
  	if (hc->new_map)
  		param->flags |= DM_INACTIVE_PRESENT_FLAG;
  	else
  		param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
  
  	return hc;
  }
  
  static struct mapped_device *find_device(struct dm_ioctl *param)
  {
  	struct hash_cell *hc;
  	struct mapped_device *md = NULL;
  
  	down_read(&_hash_lock);
  	hc = __find_device_hash_cell(param);
  	if (hc)
  		md = hc->md;
  	up_read(&_hash_lock);
  
  	return md;
  }
  
  static int dev_remove(struct dm_ioctl *param, size_t param_size)
  {
  	struct hash_cell *hc;
  	struct mapped_device *md;
  	int r;
  	struct dm_table *t;
  
  	down_write(&_hash_lock);
  	hc = __find_device_hash_cell(param);
  
  	if (!hc) {
  		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
  		up_write(&_hash_lock);
  		return -ENXIO;
  	}
  
  	md = hc->md;
  
  	/*
  	 * Ensure the device is not open and nothing further can open it.
  	 */
  	r = dm_lock_for_deletion(md, !!(param->flags & DM_DEFERRED_REMOVE), false);
  	if (r) {
  		if (r == -EBUSY && param->flags & DM_DEFERRED_REMOVE) {
  			up_write(&_hash_lock);
  			dm_put(md);
  			return 0;
  		}
  		DMDEBUG_LIMIT("unable to remove open device %s", hc->name);
  		up_write(&_hash_lock);
  		dm_put(md);
  		return r;
  	}
  
  	t = __hash_remove(hc);
  	up_write(&_hash_lock);
  
  	if (t) {
  		dm_sync_table(md);
  		dm_table_destroy(t);
  	}
  
  	param->flags &= ~DM_DEFERRED_REMOVE;
  
  	if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr))
  		param->flags |= DM_UEVENT_GENERATED_FLAG;
  
  	dm_put(md);
  	dm_destroy(md);
  	return 0;
  }
  
  /*
   * Check a string doesn't overrun the chunk of
   * memory we copied from userland.
   */
  static int invalid_str(char *str, void *end)
  {
  	while ((void *) str < end)
  		if (!*str++)
  			return 0;
  
  	return -EINVAL;
  }
  
  static int dev_rename(struct dm_ioctl *param, size_t param_size)
  {
  	int r;
  	char *new_data = (char *) param + param->data_start;
  	struct mapped_device *md;
  	unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
  
  	if (new_data < param->data ||
  	    invalid_str(new_data, (void *) param + param_size) || !*new_data ||
  	    strlen(new_data) > (change_uuid ? DM_UUID_LEN - 1 : DM_NAME_LEN - 1)) {
  		DMWARN("Invalid new mapped device name or uuid string supplied.");
  		return -EINVAL;
  	}
  
  	if (!change_uuid) {
  		r = check_name(new_data);
  		if (r)
  			return r;
  	}
  
  	md = dm_hash_rename(param, new_data);
  	if (IS_ERR(md))
  		return PTR_ERR(md);
  
  	__dev_status(md, param);
  	dm_put(md);
  
  	return 0;
  }
  
  static int dev_set_geometry(struct dm_ioctl *param, size_t param_size)
  {
  	int r = -EINVAL, x;
  	struct mapped_device *md;
  	struct hd_geometry geometry;
  	unsigned long indata[4];
  	char *geostr = (char *) param + param->data_start;
  	char dummy;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	if (geostr < param->data ||
  	    invalid_str(geostr, (void *) param + param_size)) {
  		DMWARN("Invalid geometry supplied.");
  		goto out;
  	}
  
  	x = sscanf(geostr, "%lu %lu %lu %lu%c", indata,
  		   indata + 1, indata + 2, indata + 3, &dummy);
  
  	if (x != 4) {
  		DMWARN("Unable to interpret geometry settings.");
  		goto out;
  	}
  
  	if (indata[0] > 65535 || indata[1] > 255 ||
  	    indata[2] > 255 || indata[3] > ULONG_MAX) {
  		DMWARN("Geometry exceeds range limits.");
  		goto out;
  	}
  
  	geometry.cylinders = indata[0];
  	geometry.heads = indata[1];
  	geometry.sectors = indata[2];
  	geometry.start = indata[3];
  
  	r = dm_set_geometry(md, &geometry);
  
  	param->data_size = 0;
  
  out:
  	dm_put(md);
  	return r;
  }
  
  static int do_suspend(struct dm_ioctl *param)
  {
  	int r = 0;
  	unsigned suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
  	struct mapped_device *md;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	if (param->flags & DM_SKIP_LOCKFS_FLAG)
  		suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
  	if (param->flags & DM_NOFLUSH_FLAG)
  		suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
  
  	if (!dm_suspended_md(md)) {
  		r = dm_suspend(md, suspend_flags);
  		if (r)
  			goto out;
  	}
  
  	__dev_status(md, param);
  
  out:
  	dm_put(md);
  
  	return r;
  }
  
  static int do_resume(struct dm_ioctl *param)
  {
  	int r = 0;
  	unsigned suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
  	struct hash_cell *hc;
  	struct mapped_device *md;
  	struct dm_table *new_map, *old_map = NULL;
  
  	down_write(&_hash_lock);
  
  	hc = __find_device_hash_cell(param);
  	if (!hc) {
  		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
  		up_write(&_hash_lock);
  		return -ENXIO;
  	}
  
  	md = hc->md;
  
  	new_map = hc->new_map;
  	hc->new_map = NULL;
  	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
  
  	up_write(&_hash_lock);
  
  	/* Do we need to load a new map ? */
  	if (new_map) {
  		/* Suspend if it isn't already suspended */
  		if (param->flags & DM_SKIP_LOCKFS_FLAG)
  			suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
  		if (param->flags & DM_NOFLUSH_FLAG)
  			suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
  		if (!dm_suspended_md(md))
  			dm_suspend(md, suspend_flags);
  
  		old_map = dm_swap_table(md, new_map);
  		if (IS_ERR(old_map)) {
  			dm_sync_table(md);
  			dm_table_destroy(new_map);
  			dm_put(md);
  			return PTR_ERR(old_map);
  		}
  
  		if (dm_table_get_mode(new_map) & FMODE_WRITE)
  			set_disk_ro(dm_disk(md), 0);
  		else
  			set_disk_ro(dm_disk(md), 1);
  	}
  
  	if (dm_suspended_md(md)) {
  		r = dm_resume(md);
  		if (!r && !dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr))
  			param->flags |= DM_UEVENT_GENERATED_FLAG;
  	}
  
  	/*
  	 * Since dm_swap_table synchronizes RCU, nobody should be in
  	 * read-side critical section already.
  	 */
  	if (old_map)
  		dm_table_destroy(old_map);
  
  	if (!r)
  		__dev_status(md, param);
  
  	dm_put(md);
  	return r;
  }
  
  /*
   * Set or unset the suspension state of a device.
   * If the device already is in the requested state we just return its status.
   */
  static int dev_suspend(struct dm_ioctl *param, size_t param_size)
  {
  	if (param->flags & DM_SUSPEND_FLAG)
  		return do_suspend(param);
  
  	return do_resume(param);
  }
  
  /*
   * Copies device info back to user space, used by
   * the create and info ioctls.
   */
  static int dev_status(struct dm_ioctl *param, size_t param_size)
  {
  	struct mapped_device *md;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	__dev_status(md, param);
  	dm_put(md);
  
  	return 0;
  }
  
  /*
   * Build up the status struct for each target
   */
  static void retrieve_status(struct dm_table *table,
  			    struct dm_ioctl *param, size_t param_size)
  {
  	unsigned int i, num_targets;
  	struct dm_target_spec *spec;
  	char *outbuf, *outptr;
  	status_type_t type;
  	size_t remaining, len, used = 0;
  	unsigned status_flags = 0;
  
  	outptr = outbuf = get_result_buffer(param, param_size, &len);
  
  	if (param->flags & DM_STATUS_TABLE_FLAG)
  		type = STATUSTYPE_TABLE;
  	else
  		type = STATUSTYPE_INFO;
  
  	/* Get all the target info */
  	num_targets = dm_table_get_num_targets(table);
  	for (i = 0; i < num_targets; i++) {
  		struct dm_target *ti = dm_table_get_target(table, i);
  		size_t l;
  
  		remaining = len - (outptr - outbuf);
  		if (remaining <= sizeof(struct dm_target_spec)) {
  			param->flags |= DM_BUFFER_FULL_FLAG;
  			break;
  		}
  
  		spec = (struct dm_target_spec *) outptr;
  
  		spec->status = 0;
  		spec->sector_start = ti->begin;
  		spec->length = ti->len;
  		strncpy(spec->target_type, ti->type->name,
  			sizeof(spec->target_type));
  
  		outptr += sizeof(struct dm_target_spec);
  		remaining = len - (outptr - outbuf);
  		if (remaining <= 0) {
  			param->flags |= DM_BUFFER_FULL_FLAG;
  			break;
  		}
  
  		/* Get the status/table string from the target driver */
  		if (ti->type->status) {
  			if (param->flags & DM_NOFLUSH_FLAG)
  				status_flags |= DM_STATUS_NOFLUSH_FLAG;
  			ti->type->status(ti, type, status_flags, outptr, remaining);
  		} else
  			outptr[0] = '\0';
  
  		l = strlen(outptr) + 1;
  		if (l == remaining) {
  			param->flags |= DM_BUFFER_FULL_FLAG;
  			break;
  		}
  
  		outptr += l;
  		used = param->data_start + (outptr - outbuf);
  
  		outptr = align_ptr(outptr);
  		spec->next = outptr - outbuf;
  	}
  
  	if (used)
  		param->data_size = used;
  
  	param->target_count = num_targets;
  }
  
  /*
   * Wait for a device to report an event
   */
  static int dev_wait(struct dm_ioctl *param, size_t param_size)
  {
  	int r = 0;
  	struct mapped_device *md;
  	struct dm_table *table;
  	int srcu_idx;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	/*
  	 * Wait for a notification event
  	 */
  	if (dm_wait_event(md, param->event_nr)) {
  		r = -ERESTARTSYS;
  		goto out;
  	}
  
  	/*
  	 * The userland program is going to want to know what
  	 * changed to trigger the event, so we may as well tell
  	 * him and save an ioctl.
  	 */
  	__dev_status(md, param);
  
  	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
  	if (table)
  		retrieve_status(table, param, param_size);
  	dm_put_live_table(md, srcu_idx);
  
  out:
  	dm_put(md);
  
  	return r;
  }
  
  static inline fmode_t get_mode(struct dm_ioctl *param)
  {
  	fmode_t mode = FMODE_READ | FMODE_WRITE;
  
  	if (param->flags & DM_READONLY_FLAG)
  		mode = FMODE_READ;
  
  	return mode;
  }
  
  static int next_target(struct dm_target_spec *last, uint32_t next, void *end,
  		       struct dm_target_spec **spec, char **target_params)
  {
  	*spec = (struct dm_target_spec *) ((unsigned char *) last + next);
  	*target_params = (char *) (*spec + 1);
  
  	if (*spec < (last + 1))
  		return -EINVAL;
  
  	return invalid_str(*target_params, end);
  }
  
  static int populate_table(struct dm_table *table,
  			  struct dm_ioctl *param, size_t param_size)
  {
  	int r;
  	unsigned int i = 0;
  	struct dm_target_spec *spec = (struct dm_target_spec *) param;
  	uint32_t next = param->data_start;
  	void *end = (void *) param + param_size;
  	char *target_params;
  
  	if (!param->target_count) {
  		DMWARN("populate_table: no targets specified");
  		return -EINVAL;
  	}
  
  	for (i = 0; i < param->target_count; i++) {
  
  		r = next_target(spec, next, end, &spec, &target_params);
  		if (r) {
  			DMWARN("unable to find target");
  			return r;
  		}
  
  		r = dm_table_add_target(table, spec->target_type,
  					(sector_t) spec->sector_start,
  					(sector_t) spec->length,
  					target_params);
  		if (r) {
  			DMWARN("error adding target to table");
  			return r;
  		}
  
  		next = spec->next;
  	}
  
  	return dm_table_complete(table);
  }
  
  static bool is_valid_type(unsigned cur, unsigned new)
  {
  	if (cur == new ||
  	    (cur == DM_TYPE_BIO_BASED && new == DM_TYPE_DAX_BIO_BASED))
  		return true;
  
  	return false;
  }
  
  static int table_load(struct dm_ioctl *param, size_t param_size)
  {
  	int r;
  	struct hash_cell *hc;
  	struct dm_table *t, *old_map = NULL;
  	struct mapped_device *md;
  	struct target_type *immutable_target_type;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	r = dm_table_create(&t, get_mode(param), param->target_count, md);
  	if (r)
  		goto err;
  
  	/* Protect md->type and md->queue against concurrent table loads. */
  	dm_lock_md_type(md);
  	r = populate_table(t, param, param_size);
  	if (r)
  		goto err_unlock_md_type;
  
  	immutable_target_type = dm_get_immutable_target_type(md);
  	if (immutable_target_type &&
  	    (immutable_target_type != dm_table_get_immutable_target_type(t)) &&
  	    !dm_table_get_wildcard_target(t)) {
  		DMWARN("can't replace immutable target type %s",
  		       immutable_target_type->name);
  		r = -EINVAL;
  		goto err_unlock_md_type;
  	}
  
  	if (dm_get_md_type(md) == DM_TYPE_NONE) {
  		/* Initial table load: acquire type of table. */
  		dm_set_md_type(md, dm_table_get_type(t));
  
  		/* setup md->queue to reflect md's type (may block) */
  		r = dm_setup_md_queue(md, t);
  		if (r) {
  			DMWARN("unable to set up device queue for new table.");
  			goto err_unlock_md_type;
  		}
  	} else if (!is_valid_type(dm_get_md_type(md), dm_table_get_type(t))) {
  		DMWARN("can't change device type after initial table load.");
  		r = -EINVAL;
  		goto err_unlock_md_type;
  	}
  
  	dm_unlock_md_type(md);
  
  	/* stage inactive table */
  	down_write(&_hash_lock);
  	hc = dm_get_mdptr(md);
  	if (!hc || hc->md != md) {
  		DMWARN("device has been removed from the dev hash table.");
  		up_write(&_hash_lock);
  		r = -ENXIO;
  		goto err_destroy_table;
  	}
  
  	if (hc->new_map)
  		old_map = hc->new_map;
  	hc->new_map = t;
  	up_write(&_hash_lock);
  
  	param->flags |= DM_INACTIVE_PRESENT_FLAG;
  	__dev_status(md, param);
  
  	if (old_map) {
  		dm_sync_table(md);
  		dm_table_destroy(old_map);
  	}
  
  	dm_put(md);
  
  	return 0;
  
  err_unlock_md_type:
  	dm_unlock_md_type(md);
  err_destroy_table:
  	dm_table_destroy(t);
  err:
  	dm_put(md);
  
  	return r;
  }
  
  static int table_clear(struct dm_ioctl *param, size_t param_size)
  {
  	struct hash_cell *hc;
  	struct mapped_device *md;
  	struct dm_table *old_map = NULL;
  
  	down_write(&_hash_lock);
  
  	hc = __find_device_hash_cell(param);
  	if (!hc) {
  		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
  		up_write(&_hash_lock);
  		return -ENXIO;
  	}
  
  	if (hc->new_map) {
  		old_map = hc->new_map;
  		hc->new_map = NULL;
  	}
  
  	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
  
  	__dev_status(hc->md, param);
  	md = hc->md;
  	up_write(&_hash_lock);
  	if (old_map) {
  		dm_sync_table(md);
  		dm_table_destroy(old_map);
  	}
  	dm_put(md);
  
  	return 0;
  }
  
  /*
   * Retrieves a list of devices used by a particular dm device.
   */
  static void retrieve_deps(struct dm_table *table,
  			  struct dm_ioctl *param, size_t param_size)
  {
  	unsigned int count = 0;
  	struct list_head *tmp;
  	size_t len, needed;
  	struct dm_dev_internal *dd;
  	struct dm_target_deps *deps;
  
  	deps = get_result_buffer(param, param_size, &len);
  
  	/*
  	 * Count the devices.
  	 */
  	list_for_each (tmp, dm_table_get_devices(table))
  		count++;
  
  	/*
  	 * Check we have enough space.
  	 */
  	needed = sizeof(*deps) + (sizeof(*deps->dev) * count);
  	if (len < needed) {
  		param->flags |= DM_BUFFER_FULL_FLAG;
  		return;
  	}
  
  	/*
  	 * Fill in the devices.
  	 */
  	deps->count = count;
  	count = 0;
  	list_for_each_entry (dd, dm_table_get_devices(table), list)
  		deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev);
  
  	param->data_size = param->data_start + needed;
  }
  
  static int table_deps(struct dm_ioctl *param, size_t param_size)
  {
  	struct mapped_device *md;
  	struct dm_table *table;
  	int srcu_idx;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	__dev_status(md, param);
  
  	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
  	if (table)
  		retrieve_deps(table, param, param_size);
  	dm_put_live_table(md, srcu_idx);
  
  	dm_put(md);
  
  	return 0;
  }
  
  /*
   * Return the status of a device as a text string for each
   * target.
   */
  static int table_status(struct dm_ioctl *param, size_t param_size)
  {
  	struct mapped_device *md;
  	struct dm_table *table;
  	int srcu_idx;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	__dev_status(md, param);
  
  	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
  	if (table)
  		retrieve_status(table, param, param_size);
  	dm_put_live_table(md, srcu_idx);
  
  	dm_put(md);
  
  	return 0;
  }
  
  /*
   * Process device-mapper dependent messages.  Messages prefixed with '@'
   * are processed by the DM core.  All others are delivered to the target.
   * Returns a number <= 1 if message was processed by device mapper.
   * Returns 2 if message should be delivered to the target.
   */
  static int message_for_md(struct mapped_device *md, unsigned argc, char **argv,
  			  char *result, unsigned maxlen)
  {
  	int r;
  
  	if (**argv != '@')
  		return 2; /* no '@' prefix, deliver to target */
  
  	if (!strcasecmp(argv[0], "@cancel_deferred_remove")) {
  		if (argc != 1) {
  			DMERR("Invalid arguments for @cancel_deferred_remove");
  			return -EINVAL;
  		}
  		return dm_cancel_deferred_remove(md);
  	}
  
  	r = dm_stats_message(md, argc, argv, result, maxlen);
  	if (r < 2)
  		return r;
  
  	DMERR("Unsupported message sent to DM core: %s", argv[0]);
  	return -EINVAL;
  }
  
  /*
   * Pass a message to the target that's at the supplied device offset.
   */
  static int target_message(struct dm_ioctl *param, size_t param_size)
  {
  	int r, argc;
  	char **argv;
  	struct mapped_device *md;
  	struct dm_table *table;
  	struct dm_target *ti;
  	struct dm_target_msg *tmsg = (void *) param + param->data_start;
  	size_t maxlen;
  	char *result = get_result_buffer(param, param_size, &maxlen);
  	int srcu_idx;
  
  	md = find_device(param);
  	if (!md)
  		return -ENXIO;
  
  	if (tmsg < (struct dm_target_msg *) param->data ||
  	    invalid_str(tmsg->message, (void *) param + param_size)) {
  		DMWARN("Invalid target message parameters.");
  		r = -EINVAL;
  		goto out;
  	}
  
  	r = dm_split_args(&argc, &argv, tmsg->message);
  	if (r) {
  		DMWARN("Failed to split target message parameters");
  		goto out;
  	}
  
  	if (!argc) {
  		DMWARN("Empty message received.");
  		goto out_argv;
  	}
  
  	r = message_for_md(md, argc, argv, result, maxlen);
  	if (r <= 1)
  		goto out_argv;
  
  	table = dm_get_live_table(md, &srcu_idx);
  	if (!table)
  		goto out_table;
  
  	if (dm_deleting_md(md)) {
  		r = -ENXIO;
  		goto out_table;
  	}
  
  	ti = dm_table_find_target(table, tmsg->sector);
  	if (!dm_target_is_valid(ti)) {
  		DMWARN("Target message sector outside device.");
  		r = -EINVAL;
  	} else if (ti->type->message)
  		r = ti->type->message(ti, argc, argv);
  	else {
  		DMWARN("Target type does not support messages");
  		r = -EINVAL;
  	}
  
   out_table:
  	dm_put_live_table(md, srcu_idx);
   out_argv:
  	kfree(argv);
   out:
  	if (r >= 0)
  		__dev_status(md, param);
  
  	if (r == 1) {
  		param->flags |= DM_DATA_OUT_FLAG;
  		if (dm_message_test_buffer_overflow(result, maxlen))
  			param->flags |= DM_BUFFER_FULL_FLAG;
  		else
  			param->data_size = param->data_start + strlen(result) + 1;
  		r = 0;
  	}
  
  	dm_put(md);
  	return r;
  }
  
  /*
   * The ioctl parameter block consists of two parts, a dm_ioctl struct
   * followed by a data buffer.  This flag is set if the second part,
   * which has a variable size, is not used by the function processing
   * the ioctl.
   */
  #define IOCTL_FLAGS_NO_PARAMS	1
  
  /*-----------------------------------------------------------------
   * Implementation of open/close/ioctl on the special char
   * device.
   *---------------------------------------------------------------*/
  static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
  {
  	static struct {
  		int cmd;
  		int flags;
  		ioctl_fn fn;
  	} _ioctls[] = {
  		{DM_VERSION_CMD, 0, NULL}, /* version is dealt with elsewhere */
  		{DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS, remove_all},
  		{DM_LIST_DEVICES_CMD, 0, list_devices},
  
  		{DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_create},
  		{DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_remove},
  		{DM_DEV_RENAME_CMD, 0, dev_rename},
  		{DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend},
  		{DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status},
  		{DM_DEV_WAIT_CMD, 0, dev_wait},
  
  		{DM_TABLE_LOAD_CMD, 0, table_load},
  		{DM_TABLE_CLEAR_CMD, IOCTL_FLAGS_NO_PARAMS, table_clear},
  		{DM_TABLE_DEPS_CMD, 0, table_deps},
  		{DM_TABLE_STATUS_CMD, 0, table_status},
  
  		{DM_LIST_VERSIONS_CMD, 0, list_versions},
  
  		{DM_TARGET_MSG_CMD, 0, target_message},
  		{DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry}
  	};
  
  	if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
  		return NULL;
  
  	*ioctl_flags = _ioctls[cmd].flags;
  	return _ioctls[cmd].fn;
  }
  
  /*
   * As well as checking the version compatibility this always
   * copies the kernel interface version out.
   */
  static int check_version(unsigned int cmd, struct dm_ioctl __user *user)
  {
  	uint32_t version[3];
  	int r = 0;
  
  	if (copy_from_user(version, user->version, sizeof(version)))
  		return -EFAULT;
  
  	if ((DM_VERSION_MAJOR != version[0]) ||
  	    (DM_VERSION_MINOR < version[1])) {
  		DMWARN("ioctl interface mismatch: "
  		       "kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
  		       DM_VERSION_MAJOR, DM_VERSION_MINOR,
  		       DM_VERSION_PATCHLEVEL,
  		       version[0], version[1], version[2], cmd);
  		r = -EINVAL;
  	}
  
  	/*
  	 * Fill in the kernel version.
  	 */
  	version[0] = DM_VERSION_MAJOR;
  	version[1] = DM_VERSION_MINOR;
  	version[2] = DM_VERSION_PATCHLEVEL;
  	if (copy_to_user(user->version, version, sizeof(version)))
  		return -EFAULT;
  
  	return r;
  }
  
  #define DM_PARAMS_MALLOC	0x0001	/* Params allocated with kvmalloc() */
  #define DM_WIPE_BUFFER		0x0010	/* Wipe input buffer before returning from ioctl */
  
  static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
  {
  	if (param_flags & DM_WIPE_BUFFER)
  		memset(param, 0, param_size);
  
  	if (param_flags & DM_PARAMS_MALLOC)
  		kvfree(param);
  }
  
  static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
  		       int ioctl_flags, struct dm_ioctl **param, int *param_flags)
  {
  	struct dm_ioctl *dmi;
  	int secure_data;
  	const size_t minimum_data_size = sizeof(*param_kernel) - sizeof(param_kernel->data);
  
  	if (copy_from_user(param_kernel, user, minimum_data_size))
  		return -EFAULT;
  
  	if (param_kernel->data_size < minimum_data_size)
  		return -EINVAL;
  
  	secure_data = param_kernel->flags & DM_SECURE_DATA_FLAG;
  
  	*param_flags = secure_data ? DM_WIPE_BUFFER : 0;
  
  	if (ioctl_flags & IOCTL_FLAGS_NO_PARAMS) {
  		dmi = param_kernel;
  		dmi->data_size = minimum_data_size;
  		goto data_copied;
  	}
  
  	/*
  	 * Try to avoid low memory issues when a device is suspended.
  	 * Use kmalloc() rather than vmalloc() when we can.
  	 */
  	dmi = NULL;
  	if (param_kernel->data_size <= KMALLOC_MAX_SIZE)
  		dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
  
  	if (!dmi) {
  		unsigned noio_flag;
  		noio_flag = memalloc_noio_save();
  		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
  		memalloc_noio_restore(noio_flag);
  	}
  
  	if (!dmi) {
  		if (secure_data && clear_user(user, param_kernel->data_size))
  			return -EFAULT;
  		return -ENOMEM;
  	}
  
  	*param_flags |= DM_PARAMS_MALLOC;
  
  	/* Copy from param_kernel (which was already copied from user) */
  	memcpy(dmi, param_kernel, minimum_data_size);
  
  	if (copy_from_user(&dmi->data, (char __user *)user + minimum_data_size,
  			   param_kernel->data_size - minimum_data_size))
  		goto bad;
  data_copied:
  	/* Wipe the user buffer so we do not return it to userspace */
  	if (secure_data && clear_user(user, param_kernel->data_size))
  		goto bad;
  
  	*param = dmi;
  	return 0;
  
  bad:
  	free_params(dmi, param_kernel->data_size, *param_flags);
  
  	return -EFAULT;
  }
  
  static int validate_params(uint cmd, struct dm_ioctl *param)
  {
  	/* Always clear this flag */
  	param->flags &= ~DM_BUFFER_FULL_FLAG;
  	param->flags &= ~DM_UEVENT_GENERATED_FLAG;
  	param->flags &= ~DM_SECURE_DATA_FLAG;
  	param->flags &= ~DM_DATA_OUT_FLAG;
  
  	/* Ignores parameters */
  	if (cmd == DM_REMOVE_ALL_CMD ||
  	    cmd == DM_LIST_DEVICES_CMD ||
  	    cmd == DM_LIST_VERSIONS_CMD)
  		return 0;
  
  	if (cmd == DM_DEV_CREATE_CMD) {
  		if (!*param->name) {
  			DMWARN("name not supplied when creating device");
  			return -EINVAL;
  		}
  	} else if (*param->uuid && *param->name) {
  		DMWARN("only supply one of name or uuid, cmd(%u)", cmd);
  		return -EINVAL;
  	}
  
  	/* Ensure strings are terminated */
  	param->name[DM_NAME_LEN - 1] = '\0';
  	param->uuid[DM_UUID_LEN - 1] = '\0';
  
  	return 0;
  }
  
  static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
  {
  	int r = 0;
  	int ioctl_flags;
  	int param_flags;
  	unsigned int cmd;
  	struct dm_ioctl *uninitialized_var(param);
  	ioctl_fn fn = NULL;
  	size_t input_param_size;
  	struct dm_ioctl param_kernel;
  
  	/* only root can play with this */
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;
  
  	if (_IOC_TYPE(command) != DM_IOCTL)
  		return -ENOTTY;
  
  	cmd = _IOC_NR(command);
  
  	/*
  	 * Check the interface version passed in.  This also
  	 * writes out the kernel's interface version.
  	 */
  	r = check_version(cmd, user);
  	if (r)
  		return r;
  
  	/*
  	 * Nothing more to do for the version command.
  	 */
  	if (cmd == DM_VERSION_CMD)
  		return 0;
  
  	fn = lookup_ioctl(cmd, &ioctl_flags);
  	if (!fn) {
  		DMWARN("dm_ctl_ioctl: unknown command 0x%x", command);
  		return -ENOTTY;
  	}
  
  	/*
  	 * Copy the parameters into kernel space.
  	 */
  	r = copy_params(user, &param_kernel, ioctl_flags, &param, &param_flags);
  
  	if (r)
  		return r;
  
  	input_param_size = param->data_size;
  	r = validate_params(cmd, param);
  	if (r)
  		goto out;
  
  	param->data_size = offsetof(struct dm_ioctl, data);
  	r = fn(param, input_param_size);
  
  	if (unlikely(param->flags & DM_BUFFER_FULL_FLAG) &&
  	    unlikely(ioctl_flags & IOCTL_FLAGS_NO_PARAMS))
  		DMERR("ioctl %d tried to output some data but has IOCTL_FLAGS_NO_PARAMS set", cmd);
  
  	/*
  	 * Copy the results back to userland.
  	 */
  	if (!r && copy_to_user(user, param, param->data_size))
  		r = -EFAULT;
  
  out:
  	free_params(param, input_param_size, param_flags);
  	return r;
  }
  
  static long dm_ctl_ioctl(struct file *file, uint command, ulong u)
  {
  	return (long)ctl_ioctl(command, (struct dm_ioctl __user *)u);
  }
  
  #ifdef CONFIG_COMPAT
  static long dm_compat_ctl_ioctl(struct file *file, uint command, ulong u)
  {
  	return (long)dm_ctl_ioctl(file, command, (ulong) compat_ptr(u));
  }
  #else
  #define dm_compat_ctl_ioctl NULL
  #endif
  
  static const struct file_operations _ctl_fops = {
  	.open = nonseekable_open,
  	.unlocked_ioctl	 = dm_ctl_ioctl,
  	.compat_ioctl = dm_compat_ctl_ioctl,
  	.owner	 = THIS_MODULE,
  	.llseek  = noop_llseek,
  };
  
  static struct miscdevice _dm_misc = {
  	.minor		= MAPPER_CTRL_MINOR,
  	.name  		= DM_NAME,
  	.nodename	= DM_DIR "/" DM_CONTROL_NODE,
  	.fops  		= &_ctl_fops
  };
  
  MODULE_ALIAS_MISCDEV(MAPPER_CTRL_MINOR);
  MODULE_ALIAS("devname:" DM_DIR "/" DM_CONTROL_NODE);
  
  /*
   * Create misc character device and link to DM_DIR/control.
   */
  int __init dm_interface_init(void)
  {
  	int r;
  
  	r = dm_hash_init();
  	if (r)
  		return r;
  
  	r = misc_register(&_dm_misc);
  	if (r) {
  		DMERR("misc_register failed for control device");
  		dm_hash_exit();
  		return r;
  	}
  
  	DMINFO("%d.%d.%d%s initialised: %s", DM_VERSION_MAJOR,
  	       DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL, DM_VERSION_EXTRA,
  	       DM_DRIVER_EMAIL);
  	return 0;
  }
  
  void dm_interface_exit(void)
  {
  	misc_deregister(&_dm_misc);
  	dm_hash_exit();
  }
  
  
  /**
   * dm_ioctl_export - Permanently export a mapped device via the ioctl interface
   * @md: Pointer to mapped_device
   * @name: Buffer (size DM_NAME_LEN) for name
   * @uuid: Buffer (size DM_UUID_LEN) for uuid or NULL if not desired
   */
  int dm_ioctl_export(struct mapped_device *md, const char *name,
  		    const char *uuid)
  {
  	int r = 0;
  	struct hash_cell *hc;
  
  	if (!md) {
  		r = -ENXIO;
  		goto out;
  	}
  
  	/* The name and uuid can only be set once. */
  	mutex_lock(&dm_hash_cells_mutex);
  	hc = dm_get_mdptr(md);
  	mutex_unlock(&dm_hash_cells_mutex);
  	if (hc) {
  		DMERR("%s: already exported", dm_device_name(md));
  		r = -ENXIO;
  		goto out;
  	}
  
  	r = dm_hash_insert(name, uuid, md);
  	if (r) {
  		DMERR("%s: could not bind to '%s'", dm_device_name(md), name);
  		goto out;
  	}
  
  	/* Let udev know we've changed. */
  	dm_kobject_uevent(md, KOBJ_CHANGE, dm_get_event_nr(md));
  out:
  	return r;
  }
  /**
   * dm_copy_name_and_uuid - Copy mapped device name & uuid into supplied buffers
   * @md: Pointer to mapped_device
   * @name: Buffer (size DM_NAME_LEN) for name
   * @uuid: Buffer (size DM_UUID_LEN) for uuid or empty string if uuid not defined
   */
  int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
  {
  	int r = 0;
  	struct hash_cell *hc;
  
  	if (!md)
  		return -ENXIO;
  
  	mutex_lock(&dm_hash_cells_mutex);
  	hc = dm_get_mdptr(md);
  	if (!hc || hc->md != md) {
  		r = -ENXIO;
  		goto out;
  	}
  
  	if (name)
  		strcpy(name, hc->name);
  	if (uuid)
  		strcpy(uuid, hc->uuid ? : "");
  
  out:
  	mutex_unlock(&dm_hash_cells_mutex);
  
  	return r;
  }
  