/*
   * Copyright (C) 2001 Sistina Software (UK) Limited.

   * Copyright (C) 2004-2008 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/blkdev.h>
  #include <linux/namei.h>
  #include <linux/ctype.h>

  #include <linux/string.h>

  #include <linux/slab.h>
  #include <linux/interrupt.h>

  #include <linux/mutex.h>

  #include <linux/delay.h>

  #include <linux/atomic.h>

  #include <linux/blk-mq.h>

  #include <linux/mount.h>

  #include <linux/dax.h>

  #define DM_MSG_PREFIX "table"

  #define MAX_DEPTH 16
  #define NODE_SIZE L1_CACHE_BYTES
  #define KEYS_PER_NODE (NODE_SIZE / sizeof(sector_t))
  #define CHILDREN_PER_NODE (KEYS_PER_NODE + 1)
  
  struct dm_table {

  	struct mapped_device *md;

  	enum dm_queue_mode type;

  
  	/* btree table */
  	unsigned int depth;
  	unsigned int counts[MAX_DEPTH];	/* in nodes */
  	sector_t *index[MAX_DEPTH];
  
  	unsigned int num_targets;
  	unsigned int num_allocated;
  	sector_t *highs;
  	struct dm_target *targets;

  	struct target_type *immutable_target_type;

  
  	bool integrity_supported:1;
  	bool singleton:1;
  	bool all_blk_mq:1;

  	unsigned integrity_added:1;

  	/*
  	 * Indicates the rw permissions for the new logical
  	 * device.  This should be a combination of FMODE_READ
  	 * and FMODE_WRITE.
  	 */

  	fmode_t mode;

  
  	/* a list of devices used by this table */
  	struct list_head devices;

  	/* events get handed up using this callback */
  	void (*event_fn)(void *);
  	void *event_context;

  
  	struct dm_md_mempools *mempools;

  
  	struct list_head target_callbacks;

  };
  
  /*
   * Similar to ceiling(log_size(n))
   */
  static unsigned int int_log(unsigned int n, unsigned int base)
  {
  	int result = 0;
  
  	while (n > 1) {
  		n = dm_div_up(n, base);
  		result++;
  	}
  
  	return result;
  }
  
  /*

   * Calculate the index of the child node of the n'th node k'th key.
   */
  static inline unsigned int get_child(unsigned int n, unsigned int k)
  {
  	return (n * CHILDREN_PER_NODE) + k;
  }
  
  /*
   * Return the n'th node of level l from table t.
   */
  static inline sector_t *get_node(struct dm_table *t,
  				 unsigned int l, unsigned int n)
  {
  	return t->index[l] + (n * KEYS_PER_NODE);
  }
  
  /*
   * Return the highest key that you could lookup from the n'th
   * node on level l of the btree.
   */
  static sector_t high(struct dm_table *t, unsigned int l, unsigned int n)
  {
  	for (; l < t->depth - 1; l++)
  		n = get_child(n, CHILDREN_PER_NODE - 1);
  
  	if (n >= t->counts[l])
  		return (sector_t) - 1;
  
  	return get_node(t, l, n)[KEYS_PER_NODE - 1];
  }
  
  /*
   * Fills in a level of the btree based on the highs of the level
   * below it.
   */
  static int setup_btree_index(unsigned int l, struct dm_table *t)
  {
  	unsigned int n, k;
  	sector_t *node;
  
  	for (n = 0U; n < t->counts[l]; n++) {
  		node = get_node(t, l, n);
  
  		for (k = 0U; k < KEYS_PER_NODE; k++)
  			node[k] = high(t, l + 1, get_child(n, k));
  	}
  
  	return 0;
  }
  
  void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size)
  {
  	unsigned long size;
  	void *addr;
  
  	/*
  	 * Check that we're not going to overflow.
  	 */
  	if (nmemb > (ULONG_MAX / elem_size))
  		return NULL;
  
  	size = nmemb * elem_size;

  	addr = vzalloc(size);

  
  	return addr;
  }

  EXPORT_SYMBOL(dm_vcalloc);

  
  /*
   * highs, and targets are managed as dynamic arrays during a
   * table load.
   */
  static int alloc_targets(struct dm_table *t, unsigned int num)
  {
  	sector_t *n_highs;
  	struct dm_target *n_targets;

  
  	/*
  	 * Allocate both the target array and offset array at once.

  	 * Append an empty entry to catch sectors beyond the end of
  	 * the device.

  	 */

  	n_highs = (sector_t *) dm_vcalloc(num + 1, sizeof(struct dm_target) +

  					  sizeof(sector_t));
  	if (!n_highs)
  		return -ENOMEM;
  
  	n_targets = (struct dm_target *) (n_highs + num);

  	memset(n_highs, -1, sizeof(*n_highs) * num);

  	vfree(t->highs);
  
  	t->num_allocated = num;
  	t->highs = n_highs;
  	t->targets = n_targets;
  
  	return 0;
  }

  int dm_table_create(struct dm_table **result, fmode_t mode,

  		    unsigned num_targets, struct mapped_device *md)

  {

  	struct dm_table *t = kzalloc(sizeof(*t), GFP_KERNEL);

  
  	if (!t)
  		return -ENOMEM;

  	INIT_LIST_HEAD(&t->devices);

  	INIT_LIST_HEAD(&t->target_callbacks);

  
  	if (!num_targets)
  		num_targets = KEYS_PER_NODE;
  
  	num_targets = dm_round_up(num_targets, KEYS_PER_NODE);

  	if (!num_targets) {
  		kfree(t);
  		return -ENOMEM;
  	}

  	if (alloc_targets(t, num_targets)) {
  		kfree(t);

  		return -ENOMEM;
  	}

  	t->type = DM_TYPE_NONE;

  	t->mode = mode;

  	t->md = md;

  	*result = t;
  	return 0;
  }

  static void free_devices(struct list_head *devices, struct mapped_device *md)

  {
  	struct list_head *tmp, *next;

  	list_for_each_safe(tmp, next, devices) {

  		struct dm_dev_internal *dd =
  		    list_entry(tmp, struct dm_dev_internal, list);

  		DMWARN("%s: dm_table_destroy: dm_put_device call missing for %s",
  		       dm_device_name(md), dd->dm_dev->name);
  		dm_put_table_device(md, dd->dm_dev);

  		kfree(dd);
  	}
  }

  void dm_table_destroy(struct dm_table *t)

  {
  	unsigned int i;

  	if (!t)
  		return;

  	/* free the indexes */

  	if (t->depth >= 2)
  		vfree(t->index[t->depth - 2]);
  
  	/* free the targets */
  	for (i = 0; i < t->num_targets; i++) {
  		struct dm_target *tgt = t->targets + i;
  
  		if (tgt->type->dtr)
  			tgt->type->dtr(tgt);
  
  		dm_put_target_type(tgt->type);
  	}
  
  	vfree(t->highs);
  
  	/* free the device list */

  	free_devices(&t->devices, t->md);

  	dm_free_md_mempools(t->mempools);

  	kfree(t);
  }

  /*

   * See if we've already got a device in the list.
   */

  static struct dm_dev_internal *find_device(struct list_head *l, dev_t dev)

  {

  	struct dm_dev_internal *dd;

  
  	list_for_each_entry (dd, l, list)

  		if (dd->dm_dev->bdev->bd_dev == dev)

  			return dd;
  
  	return NULL;
  }
  
  /*

   * If possible, this checks an area of a destination device is invalid.

   */

  static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
  				  sector_t start, sector_t len, void *data)

  {

  	struct request_queue *q;

  	struct queue_limits *limits = data;
  	struct block_device *bdev = dev->bdev;
  	sector_t dev_size =
  		i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;

  	unsigned short logical_block_size_sectors =

  		limits->logical_block_size >> SECTOR_SHIFT;

  	char b[BDEVNAME_SIZE];

  	/*
  	 * Some devices exist without request functions,
  	 * such as loop devices not yet bound to backing files.
  	 * Forbid the use of such devices.
  	 */
  	q = bdev_get_queue(bdev);
  	if (!q || !q->make_request_fn) {
  		DMWARN("%s: %s is not yet initialised: "
  		       "start=%llu, len=%llu, dev_size=%llu",
  		       dm_device_name(ti->table->md), bdevname(bdev, b),
  		       (unsigned long long)start,
  		       (unsigned long long)len,
  		       (unsigned long long)dev_size);
  		return 1;
  	}

  	if (!dev_size)

  		return 0;

  	if ((start >= dev_size) || (start + len > dev_size)) {

  		DMWARN("%s: %s too small for target: "
  		       "start=%llu, len=%llu, dev_size=%llu",
  		       dm_device_name(ti->table->md), bdevname(bdev, b),
  		       (unsigned long long)start,
  		       (unsigned long long)len,
  		       (unsigned long long)dev_size);

  		return 1;

  	}

  	/*
  	 * If the target is mapped to zoned block device(s), check
  	 * that the zones are not partially mapped.
  	 */
  	if (bdev_zoned_model(bdev) != BLK_ZONED_NONE) {
  		unsigned int zone_sectors = bdev_zone_sectors(bdev);
  
  		if (start & (zone_sectors - 1)) {
  			DMWARN("%s: start=%llu not aligned to h/w zone size %u of %s",
  			       dm_device_name(ti->table->md),
  			       (unsigned long long)start,
  			       zone_sectors, bdevname(bdev, b));
  			return 1;
  		}
  
  		/*
  		 * Note: The last zone of a zoned block device may be smaller
  		 * than other zones. So for a target mapping the end of a
  		 * zoned block device with such a zone, len would not be zone
  		 * aligned. We do not allow such last smaller zone to be part
  		 * of the mapping here to ensure that mappings with multiple
  		 * devices do not end up with a smaller zone in the middle of
  		 * the sector range.
  		 */
  		if (len & (zone_sectors - 1)) {
  			DMWARN("%s: len=%llu not aligned to h/w zone size %u of %s",
  			       dm_device_name(ti->table->md),
  			       (unsigned long long)len,
  			       zone_sectors, bdevname(bdev, b));
  			return 1;
  		}
  	}

  	if (logical_block_size_sectors <= 1)

  		return 0;

  
  	if (start & (logical_block_size_sectors - 1)) {
  		DMWARN("%s: start=%llu not aligned to h/w "

  		       "logical block size %u of %s",

  		       dm_device_name(ti->table->md),
  		       (unsigned long long)start,

  		       limits->logical_block_size, bdevname(bdev, b));

  		return 1;

  	}

  	if (len & (logical_block_size_sectors - 1)) {

  		DMWARN("%s: len=%llu not aligned to h/w "

  		       "logical block size %u of %s",

  		       dm_device_name(ti->table->md),

  		       (unsigned long long)len,

  		       limits->logical_block_size, bdevname(bdev, b));

  		return 1;

  	}

  	return 0;

  }
  
  /*

   * This upgrades the mode on an already open dm_dev, being

   * careful to leave things as they were if we fail to reopen the

   * device and not to touch the existing bdev field in case
   * it is accessed concurrently inside dm_table_any_congested().

   */

  static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,

  			struct mapped_device *md)

  {
  	int r;

  	struct dm_dev *old_dev, *new_dev;

  	old_dev = dd->dm_dev;

  	r = dm_get_table_device(md, dd->dm_dev->bdev->bd_dev,
  				dd->dm_dev->mode | new_mode, &new_dev);

  	if (r)
  		return r;

  	dd->dm_dev = new_dev;
  	dm_put_table_device(md, old_dev);

  	return 0;

  }
  
  /*

   * Convert the path to a device
   */
  dev_t dm_get_dev_t(const char *path)
  {

  	dev_t dev;

  	struct block_device *bdev;
  
  	bdev = lookup_bdev(path);
  	if (IS_ERR(bdev))
  		dev = name_to_dev_t(path);
  	else {
  		dev = bdev->bd_dev;
  		bdput(bdev);
  	}
  
  	return dev;
  }
  EXPORT_SYMBOL_GPL(dm_get_dev_t);
  
  /*

   * Add a device to the list, or just increment the usage count if
   * it's already present.
   */

  int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
  		  struct dm_dev **result)

  {
  	int r;

  	dev_t dev;

  	struct dm_dev_internal *dd;

  	struct dm_table *t = ti->table;

  	BUG_ON(!t);

  	dev = dm_get_dev_t(path);
  	if (!dev)
  		return -ENODEV;

  
  	dd = find_device(&t->devices, dev);
  	if (!dd) {
  		dd = kmalloc(sizeof(*dd), GFP_KERNEL);
  		if (!dd)
  			return -ENOMEM;

  		if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) {

  			kfree(dd);
  			return r;
  		}

  		atomic_set(&dd->count, 0);
  		list_add(&dd->list, &t->devices);

  	} else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {

  		r = upgrade_mode(dd, mode, t->md);

  		if (r)
  			return r;
  	}
  	atomic_inc(&dd->count);

  	*result = dd->dm_dev;

  	return 0;
  }

  EXPORT_SYMBOL(dm_get_device);

  static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
  				sector_t start, sector_t len, void *data)

  {

  	struct queue_limits *limits = data;
  	struct block_device *bdev = dev->bdev;

  	struct request_queue *q = bdev_get_queue(bdev);

  	char b[BDEVNAME_SIZE];
  
  	if (unlikely(!q)) {
  		DMWARN("%s: Cannot set limits for nonexistent device %s",
  		       dm_device_name(ti->table->md), bdevname(bdev, b));

  		return 0;

  	}

  	if (bdev_stack_limits(limits, bdev, start) < 0)
  		DMWARN("%s: adding target device %s caused an alignment inconsistency: "

  		       "physical_block_size=%u, logical_block_size=%u, "
  		       "alignment_offset=%u, start=%llu",
  		       dm_device_name(ti->table->md), bdevname(bdev, b),
  		       q->limits.physical_block_size,
  		       q->limits.logical_block_size,
  		       q->limits.alignment_offset,

  		       (unsigned long long) start << SECTOR_SHIFT);

  	limits->zoned = blk_queue_zoned_model(q);

  	return 0;

  }

  /*

   * Decrement a device's use count and remove it if necessary.

   */

  void dm_put_device(struct dm_target *ti, struct dm_dev *d)

  {

  	int found = 0;
  	struct list_head *devices = &ti->table->devices;
  	struct dm_dev_internal *dd;

  	list_for_each_entry(dd, devices, list) {
  		if (dd->dm_dev == d) {
  			found = 1;
  			break;
  		}
  	}
  	if (!found) {
  		DMWARN("%s: device %s not in table devices list",
  		       dm_device_name(ti->table->md), d->name);
  		return;
  	}

  	if (atomic_dec_and_test(&dd->count)) {

  		dm_put_table_device(ti->table->md, d);

  		list_del(&dd->list);
  		kfree(dd);
  	}
  }

  EXPORT_SYMBOL(dm_put_device);

  
  /*
   * Checks to see if the target joins onto the end of the table.
   */
  static int adjoin(struct dm_table *table, struct dm_target *ti)
  {
  	struct dm_target *prev;
  
  	if (!table->num_targets)
  		return !ti->begin;
  
  	prev = &table->targets[table->num_targets - 1];
  	return (ti->begin == (prev->begin + prev->len));
  }
  
  /*
   * Used to dynamically allocate the arg array.

   *
   * We do first allocation with GFP_NOIO because dm-mpath and dm-thin must
   * process messages even if some device is suspended. These messages have a
   * small fixed number of arguments.
   *
   * On the other hand, dm-switch needs to process bulk data using messages and
   * excessive use of GFP_NOIO could cause trouble.

   */
  static char **realloc_argv(unsigned *array_size, char **old_argv)
  {
  	char **argv;
  	unsigned new_size;

  	gfp_t gfp;

  	if (*array_size) {
  		new_size = *array_size * 2;
  		gfp = GFP_KERNEL;
  	} else {
  		new_size = 8;
  		gfp = GFP_NOIO;
  	}
  	argv = kmalloc(new_size * sizeof(*argv), gfp);

  	if (argv) {
  		memcpy(argv, old_argv, *array_size * sizeof(*argv));
  		*array_size = new_size;
  	}
  
  	kfree(old_argv);
  	return argv;
  }
  
  /*
   * Destructively splits up the argument list to pass to ctr.
   */
  int dm_split_args(int *argc, char ***argvp, char *input)
  {
  	char *start, *end = input, *out, **argv = NULL;
  	unsigned array_size = 0;
  
  	*argc = 0;

  
  	if (!input) {
  		*argvp = NULL;
  		return 0;
  	}

  	argv = realloc_argv(&array_size, argv);
  	if (!argv)
  		return -ENOMEM;
  
  	while (1) {

  		/* Skip whitespace */

  		start = skip_spaces(end);

  
  		if (!*start)
  			break;	/* success, we hit the end */
  
  		/* 'out' is used to remove any back-quotes */
  		end = out = start;
  		while (*end) {
  			/* Everything apart from '\0' can be quoted */
  			if (*end == '\\' && *(end + 1)) {
  				*out++ = *(end + 1);
  				end += 2;
  				continue;
  			}
  
  			if (isspace(*end))
  				break;	/* end of token */
  
  			*out++ = *end++;
  		}
  
  		/* have we already filled the array ? */
  		if ((*argc + 1) > array_size) {
  			argv = realloc_argv(&array_size, argv);
  			if (!argv)
  				return -ENOMEM;
  		}
  
  		/* we know this is whitespace */
  		if (*end)
  			end++;
  
  		/* terminate the string and put it in the array */
  		*out = '\0';
  		argv[*argc] = start;
  		(*argc)++;
  	}
  
  	*argvp = argv;
  	return 0;
  }

  /*
   * Impose necessary and sufficient conditions on a devices's table such
   * that any incoming bio which respects its logical_block_size can be
   * processed successfully.  If it falls across the boundary between
   * two or more targets, the size of each piece it gets split into must
   * be compatible with the logical_block_size of the target processing it.
   */

  static int validate_hardware_logical_block_alignment(struct dm_table *table,
  						 struct queue_limits *limits)

  {
  	/*
  	 * This function uses arithmetic modulo the logical_block_size
  	 * (in units of 512-byte sectors).
  	 */
  	unsigned short device_logical_block_size_sects =

  		limits->logical_block_size >> SECTOR_SHIFT;

  
  	/*
  	 * Offset of the start of the next table entry, mod logical_block_size.
  	 */
  	unsigned short next_target_start = 0;
  
  	/*
  	 * Given an aligned bio that extends beyond the end of a
  	 * target, how many sectors must the next target handle?
  	 */
  	unsigned short remaining = 0;
  
  	struct dm_target *uninitialized_var(ti);

  	struct queue_limits ti_limits;

  	unsigned i;

  
  	/*
  	 * Check each entry in the table in turn.
  	 */

  	for (i = 0; i < dm_table_get_num_targets(table); i++) {
  		ti = dm_table_get_target(table, i);

  		blk_set_stacking_limits(&ti_limits);

  
  		/* combine all target devices' limits */
  		if (ti->type->iterate_devices)
  			ti->type->iterate_devices(ti, dm_set_device_limits,
  						  &ti_limits);

  		/*
  		 * If the remaining sectors fall entirely within this
  		 * table entry are they compatible with its logical_block_size?
  		 */
  		if (remaining < ti->len &&

  		    remaining & ((ti_limits.logical_block_size >>

  				  SECTOR_SHIFT) - 1))
  			break;	/* Error */
  
  		next_target_start =
  		    (unsigned short) ((next_target_start + ti->len) &
  				      (device_logical_block_size_sects - 1));
  		remaining = next_target_start ?
  		    device_logical_block_size_sects - next_target_start : 0;
  	}
  
  	if (remaining) {
  		DMWARN("%s: table line %u (start sect %llu len %llu) "

  		       "not aligned to h/w logical block size %u",

  		       dm_device_name(table->md), i,
  		       (unsigned long long) ti->begin,
  		       (unsigned long long) ti->len,

  		       limits->logical_block_size);

  		return -EINVAL;
  	}
  
  	return 0;
  }

  int dm_table_add_target(struct dm_table *t, const char *type,
  			sector_t start, sector_t len, char *params)
  {
  	int r = -EINVAL, argc;
  	char **argv;
  	struct dm_target *tgt;

  	if (t->singleton) {
  		DMERR("%s: target type %s must appear alone in table",
  		      dm_device_name(t->md), t->targets->type->name);
  		return -EINVAL;
  	}

  	BUG_ON(t->num_targets >= t->num_allocated);

  
  	tgt = t->targets + t->num_targets;
  	memset(tgt, 0, sizeof(*tgt));
  
  	if (!len) {

  		DMERR("%s: zero-length target", dm_device_name(t->md));

  		return -EINVAL;
  	}
  
  	tgt->type = dm_get_target_type(type);
  	if (!tgt->type) {

  		DMERR("%s: %s: unknown target type", dm_device_name(t->md), type);

  		return -EINVAL;
  	}

  	if (dm_target_needs_singleton(tgt->type)) {
  		if (t->num_targets) {

  			tgt->error = "singleton target type must appear alone in table";
  			goto bad;

  		}

  		t->singleton = true;

  	}

  	if (dm_target_always_writeable(tgt->type) && !(t->mode & FMODE_WRITE)) {

  		tgt->error = "target type may not be included in a read-only table";
  		goto bad;

  	}

  	if (t->immutable_target_type) {
  		if (t->immutable_target_type != tgt->type) {

  			tgt->error = "immutable target type cannot be mixed with other target types";
  			goto bad;

  		}
  	} else if (dm_target_is_immutable(tgt->type)) {
  		if (t->num_targets) {

  			tgt->error = "immutable target type cannot be mixed with other target types";
  			goto bad;

  		}
  		t->immutable_target_type = tgt->type;
  	}

  	if (dm_target_has_integrity(tgt->type))
  		t->integrity_added = 1;

  	tgt->table = t;
  	tgt->begin = start;
  	tgt->len = len;
  	tgt->error = "Unknown error";
  
  	/*
  	 * Does this target adjoin the previous one ?
  	 */
  	if (!adjoin(t, tgt)) {
  		tgt->error = "Gap in table";

  		goto bad;
  	}
  
  	r = dm_split_args(&argc, &argv, params);
  	if (r) {
  		tgt->error = "couldn't split parameters (insufficient memory)";
  		goto bad;
  	}
  
  	r = tgt->type->ctr(tgt, argc, argv);
  	kfree(argv);
  	if (r)
  		goto bad;
  
  	t->highs[t->num_targets++] = tgt->begin + tgt->len - 1;

  	if (!tgt->num_discard_bios && tgt->discards_supported)
  		DMWARN("%s: %s: ignoring discards_supported because num_discard_bios is zero.",

  		       dm_device_name(t->md), type);

  	return 0;
  
   bad:

  	DMERR("%s: %s: %s", dm_device_name(t->md), type, tgt->error);

  	dm_put_target_type(tgt->type);
  	return r;
  }

  /*
   * Target argument parsing helpers.
   */

  static int validate_next_arg(const struct dm_arg *arg,
  			     struct dm_arg_set *arg_set,

  			     unsigned *value, char **error, unsigned grouped)
  {
  	const char *arg_str = dm_shift_arg(arg_set);

  	char dummy;

  
  	if (!arg_str ||

  	    (sscanf(arg_str, "%u%c", value, &dummy) != 1) ||

  	    (*value < arg->min) ||
  	    (*value > arg->max) ||
  	    (grouped && arg_set->argc < *value)) {
  		*error = arg->error;
  		return -EINVAL;
  	}
  
  	return 0;
  }

  int dm_read_arg(const struct dm_arg *arg, struct dm_arg_set *arg_set,

  		unsigned *value, char **error)
  {
  	return validate_next_arg(arg, arg_set, value, error, 0);
  }
  EXPORT_SYMBOL(dm_read_arg);

  int dm_read_arg_group(const struct dm_arg *arg, struct dm_arg_set *arg_set,

  		      unsigned *value, char **error)
  {
  	return validate_next_arg(arg, arg_set, value, error, 1);
  }
  EXPORT_SYMBOL(dm_read_arg_group);
  
  const char *dm_shift_arg(struct dm_arg_set *as)
  {
  	char *r;
  
  	if (as->argc) {
  		as->argc--;
  		r = *as->argv;
  		as->argv++;
  		return r;
  	}
  
  	return NULL;
  }
  EXPORT_SYMBOL(dm_shift_arg);
  
  void dm_consume_args(struct dm_arg_set *as, unsigned num_args)
  {
  	BUG_ON(as->argc < num_args);
  	as->argc -= num_args;
  	as->argv += num_args;
  }
  EXPORT_SYMBOL(dm_consume_args);

  static bool __table_type_bio_based(enum dm_queue_mode table_type)

  {
  	return (table_type == DM_TYPE_BIO_BASED ||
  		table_type == DM_TYPE_DAX_BIO_BASED);
  }

  static bool __table_type_request_based(enum dm_queue_mode table_type)

  {
  	return (table_type == DM_TYPE_REQUEST_BASED ||
  		table_type == DM_TYPE_MQ_REQUEST_BASED);
  }

  void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type)

  {
  	t->type = type;
  }
  EXPORT_SYMBOL_GPL(dm_table_set_type);

  static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
  			       sector_t start, sector_t len, void *data)
  {

  	return bdev_dax_supported(dev->bdev, PAGE_SIZE);

  }
  
  static bool dm_table_supports_dax(struct dm_table *t)
  {
  	struct dm_target *ti;

  	unsigned i;

  
  	/* Ensure that all targets support DAX. */

  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);

  
  		if (!ti->type->direct_access)
  			return false;
  
  		if (!ti->type->iterate_devices ||
  		    !ti->type->iterate_devices(ti, device_supports_dax, NULL))
  			return false;
  	}
  
  	return true;
  }

  static int dm_table_determine_type(struct dm_table *t)

  {
  	unsigned i;

  	unsigned bio_based = 0, request_based = 0, hybrid = 0;

  	unsigned sq_count = 0, mq_count = 0;

  	struct dm_target *tgt;
  	struct dm_dev_internal *dd;

  	struct list_head *devices = dm_table_get_devices(t);

  	enum dm_queue_mode live_md_type = dm_get_md_type(t->md);

  	if (t->type != DM_TYPE_NONE) {
  		/* target already set the table's type */
  		if (t->type == DM_TYPE_BIO_BASED)
  			return 0;

  		BUG_ON(t->type == DM_TYPE_DAX_BIO_BASED);

  		goto verify_rq_based;
  	}

  	for (i = 0; i < t->num_targets; i++) {
  		tgt = t->targets + i;

  		if (dm_target_hybrid(tgt))
  			hybrid = 1;
  		else if (dm_target_request_based(tgt))

  			request_based = 1;
  		else
  			bio_based = 1;
  
  		if (bio_based && request_based) {
  			DMWARN("Inconsistent table: different target types"
  			       " can't be mixed up");
  			return -EINVAL;
  		}
  	}

  	if (hybrid && !bio_based && !request_based) {
  		/*
  		 * The targets can work either way.
  		 * Determine the type from the live device.
  		 * Default to bio-based if device is new.
  		 */

  		if (__table_type_request_based(live_md_type))

  			request_based = 1;
  		else
  			bio_based = 1;
  	}

  	if (bio_based) {
  		/* We must use this table as bio-based */
  		t->type = DM_TYPE_BIO_BASED;

  		if (dm_table_supports_dax(t) ||
  		    (list_empty(devices) && live_md_type == DM_TYPE_DAX_BIO_BASED))

  			t->type = DM_TYPE_DAX_BIO_BASED;

  		return 0;
  	}
  
  	BUG_ON(!request_based); /* No targets in this table */

  	/*
  	 * The only way to establish DM_TYPE_MQ_REQUEST_BASED is by
  	 * having a compatible target use dm_table_set_type.
  	 */
  	t->type = DM_TYPE_REQUEST_BASED;
  
  verify_rq_based:

  	/*
  	 * Request-based dm supports only tables that have a single target now.
  	 * To support multiple targets, request splitting support is needed,
  	 * and that needs lots of changes in the block-layer.
  	 * (e.g. request completion process for partial completion.)
  	 */
  	if (t->num_targets > 1) {
  		DMWARN("Request-based dm doesn't support multiple targets yet");
  		return -EINVAL;
  	}

  	if (list_empty(devices)) {
  		int srcu_idx;
  		struct dm_table *live_table = dm_get_live_table(t->md, &srcu_idx);
  
  		/* inherit live table's type and all_blk_mq */
  		if (live_table) {
  			t->type = live_table->type;
  			t->all_blk_mq = live_table->all_blk_mq;
  		}
  		dm_put_live_table(t->md, srcu_idx);
  		return 0;
  	}

  	/* Non-request-stackable devices can't be used for request-based dm */

  	list_for_each_entry(dd, devices, list) {

  		struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
  
  		if (!blk_queue_stackable(q)) {
  			DMERR("table load rejected: including"
  			      " non-request-stackable devices");

  			return -EINVAL;
  		}

  
  		if (q->mq_ops)

  			mq_count++;
  		else
  			sq_count++;

  	}

  	if (sq_count && mq_count) {
  		DMERR("table load rejected: not all devices are blk-mq request-stackable");
  		return -EINVAL;

  	}

  	t->all_blk_mq = mq_count > 0;

  	if (t->type == DM_TYPE_MQ_REQUEST_BASED && !t->all_blk_mq) {
  		DMERR("table load rejected: all devices are not blk-mq request-stackable");
  		return -EINVAL;
  	}

  	return 0;
  }

  enum dm_queue_mode dm_table_get_type(struct dm_table *t)

  {
  	return t->type;
  }

  struct target_type *dm_table_get_immutable_target_type(struct dm_table *t)
  {
  	return t->immutable_target_type;
  }

  struct dm_target *dm_table_get_immutable_target(struct dm_table *t)
  {
  	/* Immutable target is implicitly a singleton */
  	if (t->num_targets > 1 ||
  	    !dm_target_is_immutable(t->targets[0].type))
  		return NULL;
  
  	return t->targets;
  }

  struct dm_target *dm_table_get_wildcard_target(struct dm_table *t)
  {

  	struct dm_target *ti;
  	unsigned i;

  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);

  		if (dm_target_is_wildcard(ti->type))
  			return ti;
  	}
  
  	return NULL;
  }

  bool dm_table_bio_based(struct dm_table *t)
  {
  	return __table_type_bio_based(dm_table_get_type(t));
  }

  bool dm_table_request_based(struct dm_table *t)
  {

  	return __table_type_request_based(dm_table_get_type(t));

  }

  bool dm_table_all_blk_mq_devices(struct dm_table *t)

  {

  	return t->all_blk_mq;

  }

  static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *md)

  {

  	enum dm_queue_mode type = dm_table_get_type(t);

  	unsigned per_io_data_size = 0;

  	struct dm_target *tgt;

  	unsigned i;

  	if (unlikely(type == DM_TYPE_NONE)) {

  		DMWARN("no table type is set, can't allocate mempools");
  		return -EINVAL;
  	}

  	if (__table_type_bio_based(type))

  		for (i = 0; i < t->num_targets; i++) {
  			tgt = t->targets + i;

  			per_io_data_size = max(per_io_data_size, tgt->per_io_data_size);

  		}

  	t->mempools = dm_alloc_md_mempools(md, type, t->integrity_supported, per_io_data_size);

  	if (!t->mempools)
  		return -ENOMEM;

  
  	return 0;
  }
  
  void dm_table_free_md_mempools(struct dm_table *t)
  {
  	dm_free_md_mempools(t->mempools);
  	t->mempools = NULL;
  }
  
  struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t)
  {
  	return t->mempools;
  }

  static int setup_indexes(struct dm_table *t)
  {
  	int i;
  	unsigned int total = 0;
  	sector_t *indexes;
  
  	/* allocate the space for *all* the indexes */
  	for (i = t->depth - 2; i >= 0; i--) {
  		t->counts[i] = dm_div_up(t->counts[i + 1], CHILDREN_PER_NODE);
  		total += t->counts[i];
  	}
  
  	indexes = (sector_t *) dm_vcalloc(total, (unsigned long) NODE_SIZE);
  	if (!indexes)
  		return -ENOMEM;
  
  	/* set up internal nodes, bottom-up */

  	for (i = t->depth - 2; i >= 0; i--) {

  		t->index[i] = indexes;
  		indexes += (KEYS_PER_NODE * t->counts[i]);
  		setup_btree_index(i, t);
  	}
  
  	return 0;
  }
  
  /*
   * Builds the btree to index the map.
   */

  static int dm_table_build_index(struct dm_table *t)

  {
  	int r = 0;
  	unsigned int leaf_nodes;

  	/* how many indexes will the btree have ? */
  	leaf_nodes = dm_div_up(t->num_targets, KEYS_PER_NODE);
  	t->depth = 1 + int_log(leaf_nodes, CHILDREN_PER_NODE);
  
  	/* leaf layer has already been set up */
  	t->counts[t->depth - 1] = leaf_nodes;
  	t->index[t->depth - 1] = t->highs;
  
  	if (t->depth >= 2)
  		r = setup_indexes(t);
  
  	return r;
  }

  static bool integrity_profile_exists(struct gendisk *disk)
  {
  	return !!blk_get_integrity(disk);
  }

  /*

   * Get a disk whose integrity profile reflects the table's profile.

   * Returns NULL if integrity support was inconsistent or unavailable.
   */

  static struct gendisk * dm_table_get_integrity_disk(struct dm_table *t)

  {
  	struct list_head *devices = dm_table_get_devices(t);
  	struct dm_dev_internal *dd = NULL;
  	struct gendisk *prev_disk = NULL, *template_disk = NULL;

  	unsigned i;
  
  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		struct dm_target *ti = dm_table_get_target(t, i);
  		if (!dm_target_passes_integrity(ti->type))
  			goto no_integrity;
  	}

  
  	list_for_each_entry(dd, devices, list) {

  		template_disk = dd->dm_dev->bdev->bd_disk;

  		if (!integrity_profile_exists(template_disk))

  			goto no_integrity;

  		else if (prev_disk &&
  			 blk_integrity_compare(prev_disk, template_disk) < 0)
  			goto no_integrity;
  		prev_disk = template_disk;
  	}
  
  	return template_disk;
  
  no_integrity:
  	if (prev_disk)
  		DMWARN("%s: integrity not set: %s and %s profile mismatch",
  		       dm_device_name(t->md),
  		       prev_disk->disk_name,
  		       template_disk->disk_name);
  	return NULL;
  }
  
  /*

   * Register the mapped device for blk_integrity support if the
   * underlying devices have an integrity profile.  But all devices may
   * not have matching profiles (checking all devices isn't reliable

   * during table load because this table may use other DM device(s) which

   * must be resumed before they will have an initialized integity
   * profile).  Consequently, stacked DM devices force a 2 stage integrity
   * profile validation: First pass during table load, final pass during
   * resume.

   */

  static int dm_table_register_integrity(struct dm_table *t)

  {

  	struct mapped_device *md = t->md;

  	struct gendisk *template_disk = NULL;

  	/* If target handles integrity itself do not register it here. */
  	if (t->integrity_added)
  		return 0;

  	template_disk = dm_table_get_integrity_disk(t);

  	if (!template_disk)
  		return 0;

  	if (!integrity_profile_exists(dm_disk(md))) {

  		t->integrity_supported = true;

  		/*
  		 * Register integrity profile during table load; we can do
  		 * this because the final profile must match during resume.
  		 */
  		blk_integrity_register(dm_disk(md),
  				       blk_get_integrity(template_disk));
  		return 0;

  	}
  
  	/*

  	 * If DM device already has an initialized integrity

  	 * profile the new profile should not conflict.
  	 */

  	if (blk_integrity_compare(dm_disk(md), template_disk) < 0) {

  		DMWARN("%s: conflict with existing integrity profile: "
  		       "%s profile mismatch",
  		       dm_device_name(t->md),
  		       template_disk->disk_name);
  		return 1;
  	}

  	/* Preserve existing integrity profile */

  	t->integrity_supported = true;

  	return 0;
  }
  
  /*
   * Prepares the table for use by building the indices,
   * setting the type, and allocating mempools.
   */
  int dm_table_complete(struct dm_table *t)
  {
  	int r;

  	r = dm_table_determine_type(t);

  	if (r) {

  		DMERR("unable to determine table type");

  		return r;
  	}
  
  	r = dm_table_build_index(t);
  	if (r) {
  		DMERR("unable to build btrees");
  		return r;
  	}

  	r = dm_table_register_integrity(t);

  	if (r) {
  		DMERR("could not register integrity profile.");
  		return r;
  	}

  	r = dm_table_alloc_md_mempools(t, t->md);

  	if (r)
  		DMERR("unable to allocate mempools");
  
  	return r;
  }

  static DEFINE_MUTEX(_event_lock);

  void dm_table_event_callback(struct dm_table *t,
  			     void (*fn)(void *), void *context)
  {

  	mutex_lock(&_event_lock);

  	t->event_fn = fn;
  	t->event_context = context;

  	mutex_unlock(&_event_lock);

  }
  
  void dm_table_event(struct dm_table *t)
  {
  	/*
  	 * You can no longer call dm_table_event() from interrupt
  	 * context, use a bottom half instead.
  	 */
  	BUG_ON(in_interrupt());

  	mutex_lock(&_event_lock);

  	if (t->event_fn)
  		t->event_fn(t->event_context);

  	mutex_unlock(&_event_lock);

  }

  EXPORT_SYMBOL(dm_table_event);

  
  sector_t dm_table_get_size(struct dm_table *t)
  {
  	return t->num_targets ? (t->highs[t->num_targets - 1] + 1) : 0;
  }

  EXPORT_SYMBOL(dm_table_get_size);

  
  struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index)
  {

  	if (index >= t->num_targets)

  		return NULL;
  
  	return t->targets + index;
  }
  
  /*
   * Search the btree for the correct target.

   *
   * Caller should check returned pointer with dm_target_is_valid()
   * to trap I/O beyond end of device.

   */
  struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector)
  {
  	unsigned int l, n = 0, k = 0;
  	sector_t *node;
  
  	for (l = 0; l < t->depth; l++) {
  		n = get_child(n, k);
  		node = get_node(t, l, n);
  
  		for (k = 0; k < KEYS_PER_NODE; k++)
  			if (node[k] >= sector)
  				break;
  	}
  
  	return &t->targets[(KEYS_PER_NODE * n) + k];
  }

  static int count_device(struct dm_target *ti, struct dm_dev *dev,
  			sector_t start, sector_t len, void *data)
  {
  	unsigned *num_devices = data;
  
  	(*num_devices)++;
  
  	return 0;
  }
  
  /*
   * Check whether a table has no data devices attached using each
   * target's iterate_devices method.
   * Returns false if the result is unknown because a target doesn't
   * support iterate_devices.
   */
  bool dm_table_has_no_data_devices(struct dm_table *table)
  {

  	struct dm_target *ti;
  	unsigned i, num_devices;

  	for (i = 0; i < dm_table_get_num_targets(table); i++) {
  		ti = dm_table_get_target(table, i);

  
  		if (!ti->type->iterate_devices)
  			return false;

  		num_devices = 0;

  		ti->type->iterate_devices(ti, count_device, &num_devices);
  		if (num_devices)
  			return false;
  	}
  
  	return true;
  }

  static int device_is_zoned_model(struct dm_target *ti, struct dm_dev *dev,
  				 sector_t start, sector_t len, void *data)
  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);
  	enum blk_zoned_model *zoned_model = data;
  
  	return q && blk_queue_zoned_model(q) == *zoned_model;
  }
  
  static bool dm_table_supports_zoned_model(struct dm_table *t,
  					  enum blk_zoned_model zoned_model)
  {
  	struct dm_target *ti;
  	unsigned i;
  
  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);
  
  		if (zoned_model == BLK_ZONED_HM &&
  		    !dm_target_supports_zoned_hm(ti->type))
  			return false;
  
  		if (!ti->type->iterate_devices ||
  		    !ti->type->iterate_devices(ti, device_is_zoned_model, &zoned_model))
  			return false;
  	}
  
  	return true;
  }
  
  static int device_matches_zone_sectors(struct dm_target *ti, struct dm_dev *dev,
  				       sector_t start, sector_t len, void *data)
  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);
  	unsigned int *zone_sectors = data;
  
  	return q && blk_queue_zone_sectors(q) == *zone_sectors;
  }
  
  static bool dm_table_matches_zone_sectors(struct dm_table *t,
  					  unsigned int zone_sectors)
  {
  	struct dm_target *ti;
  	unsigned i;
  
  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);
  
  		if (!ti->type->iterate_devices ||
  		    !ti->type->iterate_devices(ti, device_matches_zone_sectors, &zone_sectors))
  			return false;
  	}
  
  	return true;
  }
  
  static int validate_hardware_zoned_model(struct dm_table *table,
  					 enum blk_zoned_model zoned_model,
  					 unsigned int zone_sectors)
  {
  	if (zoned_model == BLK_ZONED_NONE)
  		return 0;
  
  	if (!dm_table_supports_zoned_model(table, zoned_model)) {
  		DMERR("%s: zoned model is not consistent across all devices",
  		      dm_device_name(table->md));
  		return -EINVAL;
  	}
  
  	/* Check zone size validity and compatibility */
  	if (!zone_sectors || !is_power_of_2(zone_sectors))
  		return -EINVAL;
  
  	if (!dm_table_matches_zone_sectors(table, zone_sectors)) {
  		DMERR("%s: zone sectors is not consistent across all devices",
  		      dm_device_name(table->md));
  		return -EINVAL;
  	}
  
  	return 0;
  }

  /*

   * Establish the new table's queue_limits and validate them.
   */
  int dm_calculate_queue_limits(struct dm_table *table,
  			      struct queue_limits *limits)
  {

  	struct dm_target *ti;

  	struct queue_limits ti_limits;

  	unsigned i;

  	enum blk_zoned_model zoned_model = BLK_ZONED_NONE;
  	unsigned int zone_sectors = 0;

  	blk_set_stacking_limits(limits);

  	for (i = 0; i < dm_table_get_num_targets(table); i++) {

  		blk_set_stacking_limits(&ti_limits);

  		ti = dm_table_get_target(table, i);

  
  		if (!ti->type->iterate_devices)
  			goto combine_limits;
  
  		/*
  		 * Combine queue limits of all the devices this target uses.
  		 */
  		ti->type->iterate_devices(ti, dm_set_device_limits,
  					  &ti_limits);

  		if (zoned_model == BLK_ZONED_NONE && ti_limits.zoned != BLK_ZONED_NONE) {
  			/*
  			 * After stacking all limits, validate all devices
  			 * in table support this zoned model and zone sectors.
  			 */
  			zoned_model = ti_limits.zoned;
  			zone_sectors = ti_limits.chunk_sectors;
  		}

  		/* Set I/O hints portion of queue limits */
  		if (ti->type->io_hints)
  			ti->type->io_hints(ti, &ti_limits);

  		/*
  		 * Check each device area is consistent with the target's
  		 * overall queue limits.
  		 */

  		if (ti->type->iterate_devices(ti, device_area_is_invalid,
  					      &ti_limits))

  			return -EINVAL;
  
  combine_limits:
  		/*
  		 * Merge this target's queue limits into the overall limits
  		 * for the table.
  		 */
  		if (blk_stack_limits(limits, &ti_limits, 0) < 0)

  			DMWARN("%s: adding target device "

  			       "(start sect %llu len %llu) "

  			       "caused an alignment inconsistency",

  			       dm_device_name(table->md),
  			       (unsigned long long) ti->begin,
  			       (unsigned long long) ti->len);

  
  		/*
  		 * FIXME: this should likely be moved to blk_stack_limits(), would
  		 * also eliminate limits->zoned stacking hack in dm_set_device_limits()
  		 */
  		if (limits->zoned == BLK_ZONED_NONE && ti_limits.zoned != BLK_ZONED_NONE) {
  			/*
  			 * By default, the stacked limits zoned model is set to
  			 * BLK_ZONED_NONE in blk_set_stacking_limits(). Update
  			 * this model using the first target model reported
  			 * that is not BLK_ZONED_NONE. This will be either the
  			 * first target device zoned model or the model reported
  			 * by the target .io_hints.
  			 */
  			limits->zoned = ti_limits.zoned;
  		}

  	}

  	/*
  	 * Verify that the zoned model and zone sectors, as determined before
  	 * any .io_hints override, are the same across all devices in the table.
  	 * - this is especially relevant if .io_hints is emulating a disk-managed
  	 *   zoned model (aka BLK_ZONED_NONE) on host-managed zoned block devices.
  	 * BUT...
  	 */
  	if (limits->zoned != BLK_ZONED_NONE) {
  		/*
  		 * ...IF the above limits stacking determined a zoned model
  		 * validate that all of the table's devices conform to it.
  		 */
  		zoned_model = limits->zoned;
  		zone_sectors = limits->chunk_sectors;
  	}
  	if (validate_hardware_zoned_model(table, zoned_model, zone_sectors))
  		return -EINVAL;

  	return validate_hardware_logical_block_alignment(table, limits);
  }
  
  /*

   * Verify that all devices have an integrity profile that matches the
   * DM device's registered integrity profile.  If the profiles don't
   * match then unregister the DM device's integrity profile.

   */

  static void dm_table_verify_integrity(struct dm_table *t)

  {

  	struct gendisk *template_disk = NULL;

  	if (t->integrity_added)
  		return;

  	if (t->integrity_supported) {
  		/*
  		 * Verify that the original integrity profile
  		 * matches all the devices in this table.
  		 */
  		template_disk = dm_table_get_integrity_disk(t);
  		if (template_disk &&
  		    blk_integrity_compare(dm_disk(t->md), template_disk) >= 0)
  			return;
  	}

  	if (integrity_profile_exists(dm_disk(t->md))) {

  		DMWARN("%s: unable to establish an integrity profile",
  		       dm_device_name(t->md));

  		blk_integrity_unregister(dm_disk(t->md));
  	}

  }

  static int device_flush_capable(struct dm_target *ti, struct dm_dev *dev,
  				sector_t start, sector_t len, void *data)
  {

  	unsigned long flush = (unsigned long) data;

  	struct request_queue *q = bdev_get_queue(dev->bdev);

  	return q && (q->queue_flags & flush);

  }

  static bool dm_table_supports_flush(struct dm_table *t, unsigned long flush)

  {
  	struct dm_target *ti;

  	unsigned i;

  
  	/*
  	 * Require at least one underlying device to support flushes.
  	 * t->devices includes internal dm devices such as mirror logs
  	 * so we need to use iterate_devices here, which targets
  	 * supporting flushes must provide.
  	 */

  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);

  		if (!ti->num_flush_bios)

  			continue;

  		if (ti->flush_supported)

  			return true;

  		if (ti->type->iterate_devices &&

  		    ti->type->iterate_devices(ti, device_flush_capable, (void *) flush))

  			return true;

  	}

  	return false;

  }

  static int device_dax_write_cache_enabled(struct dm_target *ti,
  					  struct dm_dev *dev, sector_t start,
  					  sector_t len, void *data)
  {
  	struct dax_device *dax_dev = dev->dax_dev;
  
  	if (!dax_dev)
  		return false;
  
  	if (dax_write_cache_enabled(dax_dev))
  		return true;
  	return false;
  }
  
  static int dm_table_supports_dax_write_cache(struct dm_table *t)
  {
  	struct dm_target *ti;
  	unsigned i;
  
  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);
  
  		if (ti->type->iterate_devices &&
  		    ti->type->iterate_devices(ti,
  				device_dax_write_cache_enabled, NULL))
  			return true;
  	}
  
  	return false;
  }

  static int device_is_nonrot(struct dm_target *ti, struct dm_dev *dev,
  			    sector_t start, sector_t len, void *data)
  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);
  
  	return q && blk_queue_nonrot(q);
  }

  static int device_is_not_random(struct dm_target *ti, struct dm_dev *dev,
  			     sector_t start, sector_t len, void *data)
  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);
  
  	return q && !blk_queue_add_random(q);
  }

  static int queue_supports_sg_merge(struct dm_target *ti, struct dm_dev *dev,
  				   sector_t start, sector_t len, void *data)
  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);
  
  	return q && !test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags);
  }

  static bool dm_table_all_devices_attribute(struct dm_table *t,
  					   iterate_devices_callout_fn func)

  {
  	struct dm_target *ti;

  	unsigned i;

  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);

  
  		if (!ti->type->iterate_devices ||

  		    !ti->type->iterate_devices(ti, func, NULL))

  			return false;

  	}

  	return true;

  }

  static int device_not_write_same_capable(struct dm_target *ti, struct dm_dev *dev,
  					 sector_t start, sector_t len, void *data)
  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);
  
  	return q && !q->limits.max_write_same_sectors;
  }
  
  static bool dm_table_supports_write_same(struct dm_table *t)
  {
  	struct dm_target *ti;

  	unsigned i;

  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);

  		if (!ti->num_write_same_bios)

  			return false;
  
  		if (!ti->type->iterate_devices ||

  		    ti->type->iterate_devices(ti, device_not_write_same_capable, NULL))

  			return false;
  	}
  
  	return true;
  }

  static int device_not_write_zeroes_capable(struct dm_target *ti, struct dm_dev *dev,
  					   sector_t start, sector_t len, void *data)
  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);
  
  	return q && !q->limits.max_write_zeroes_sectors;
  }
  
  static bool dm_table_supports_write_zeroes(struct dm_table *t)
  {
  	struct dm_target *ti;
  	unsigned i = 0;
  
  	while (i < dm_table_get_num_targets(t)) {
  		ti = dm_table_get_target(t, i++);
  
  		if (!ti->num_write_zeroes_bios)
  			return false;
  
  		if (!ti->type->iterate_devices ||
  		    ti->type->iterate_devices(ti, device_not_write_zeroes_capable, NULL))
  			return false;
  	}
  
  	return true;
  }

  static int device_not_discard_capable(struct dm_target *ti, struct dm_dev *dev,
  				      sector_t start, sector_t len, void *data)

  {
  	struct request_queue *q = bdev_get_queue(dev->bdev);

  	return q && !blk_queue_discard(q);

  }
  
  static bool dm_table_supports_discards(struct dm_table *t)
  {
  	struct dm_target *ti;

  	unsigned i;

  	for (i = 0; i < dm_table_get_num_targets(t); i++) {
  		ti = dm_table_get_target(t, i);

  
  		if (!ti->num_discard_bios)

  			return false;

  		/*
  		 * Either the target provides discard support (as implied by setting
  		 * 'discards_supported') or it relies on _all_ data devices having
  		 * discard support.
  		 */
  		if (!ti->discards_supported &&
  		    (!ti->type->iterate_devices ||
  		     ti->type->iterate_devices(ti, device_not_discard_capable, NULL)))
  			return false;

  	}

  	return true;

  }

  void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
  			       struct queue_limits *limits)

  {

  	bool wc = false, fua = false;

  	/*

  	 * Copy table's limits to the DM device's request_queue

  	 */

  	q->limits = *limits;

  	if (!dm_table_supports_discards(t))
  		queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
  	else
  		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);

  	if (dm_table_supports_flush(t, (1UL << QUEUE_FLAG_WC))) {

  		wc = true;

  		if (dm_table_supports_flush(t, (1UL << QUEUE_FLAG_FUA)))

  			fua = true;

  	}

  	blk_queue_write_cache(q, wc, fua);

  	if (dm_table_supports_dax(t))
  		queue_flag_set_unlocked(QUEUE_FLAG_DAX, q);

  	else
  		queue_flag_clear_unlocked(QUEUE_FLAG_DAX, q);

  	if (dm_table_supports_dax_write_cache(t))
  		dax_write_cache(t->md->dax_dev, true);

  	/* Ensure that all underlying devices are non-rotational. */
  	if (dm_table_all_devices_attribute(t, device_is_nonrot))

  		queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
  	else
  		queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);

  	if (!dm_table_supports_write_same(t))
  		q->limits.max_write_same_sectors = 0;

  	if (!dm_table_supports_write_zeroes(t))
  		q->limits.max_write_zeroes_sectors = 0;

  	if (dm_table_all_devices_attribute(t, queue_supports_sg_merge))
  		queue_flag_clear_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);
  	else
  		queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);

  	dm_table_verify_integrity(t);

  
  	/*

  	 * Determine whether or not this queue's I/O timings contribute
  	 * to the entropy pool, Only request-based targets use this.
  	 * Clear QUEUE_FLAG_ADD_RANDOM if any underlying device does not
  	 * have it set.
  	 */
  	if (blk_queue_add_random(q) && dm_table_all_devices_attribute(t, device_is_not_random))
  		queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, q);
  
  	/*

  	 * QUEUE_FLAG_STACKABLE must be set after all queue settings are
  	 * visible to other CPUs because, once the flag is set, incoming bios
  	 * are processed by request-based dm, which refers to the queue
  	 * settings.
  	 * Until the flag set, bios are passed to bio-based dm and queued to
  	 * md->deferred where queue settings are not needed yet.
  	 * Those bios are passed to request-based dm at the resume time.
  	 */
  	smp_mb();
  	if (dm_table_request_based(t))
  		queue_flag_set_unlocked(QUEUE_FLAG_STACKABLE, q);

  }
  
  unsigned int dm_table_get_num_targets(struct dm_table *t)
  {
  	return t->num_targets;
  }
  
  struct list_head *dm_table_get_devices(struct dm_table *t)
  {
  	return &t->devices;
  }

  fmode_t dm_table_get_mode(struct dm_table *t)

  {
  	return t->mode;
  }

  EXPORT_SYMBOL(dm_table_get_mode);

  enum suspend_mode {
  	PRESUSPEND,
  	PRESUSPEND_UNDO,
  	POSTSUSPEND,
  };
  
  static void suspend_targets(struct dm_table *t, enum suspend_mode mode)

  {
  	int i = t->num_targets;
  	struct dm_target *ti = t->targets;

  	lockdep_assert_held(&t->md->suspend_lock);

  	while (i--) {

  		switch (mode) {
  		case PRESUSPEND:
  			if (ti->type->presuspend)
  				ti->type->presuspend(ti);
  			break;
  		case PRESUSPEND_UNDO:
  			if (ti->type->presuspend_undo)
  				ti->type->presuspend_undo(ti);
  			break;
  		case POSTSUSPEND:

  			if (ti->type->postsuspend)
  				ti->type->postsuspend(ti);

  			break;
  		}

  		ti++;
  	}
  }
  
  void dm_table_presuspend_targets(struct dm_table *t)
  {

  	if (!t)
  		return;

  	suspend_targets(t, PRESUSPEND);
  }
  
  void dm_table_presuspend_undo_targets(struct dm_table *t)
  {
  	if (!t)
  		return;
  
  	suspend_targets(t, PRESUSPEND_UNDO);

  }
  
  void dm_table_postsuspend_targets(struct dm_table *t)
  {

  	if (!t)
  		return;

  	suspend_targets(t, POSTSUSPEND);

  }

  int dm_table_resume_targets(struct dm_table *t)

  {

  	int i, r = 0;

  	lockdep_assert_held(&t->md->suspend_lock);

  	for (i = 0; i < t->num_targets; i++) {
  		struct dm_target *ti = t->targets + i;
  
  		if (!ti->type->preresume)
  			continue;
  
  		r = ti->type->preresume(ti);

  		if (r) {
  			DMERR("%s: %s: preresume failed, error = %d",
  			      dm_device_name(t->md), ti->type->name, r);

  			return r;

  		}

  	}

  
  	for (i = 0; i < t->num_targets; i++) {
  		struct dm_target *ti = t->targets + i;
  
  		if (ti->type->resume)
  			ti->type->resume(ti);
  	}

  
  	return 0;

  }

  void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb)
  {
  	list_add(&cb->list, &t->target_callbacks);
  }
  EXPORT_SYMBOL_GPL(dm_table_add_target_callbacks);

  int dm_table_any_congested(struct dm_table *t, int bdi_bits)
  {

  	struct dm_dev_internal *dd;

  	struct list_head *devices = dm_table_get_devices(t);

  	struct dm_target_callbacks *cb;

  	int r = 0;

  	list_for_each_entry(dd, devices, list) {

  		struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);

  		char b[BDEVNAME_SIZE];
  
  		if (likely(q))

  			r |= bdi_congested(q->backing_dev_info, bdi_bits);

  		else
  			DMWARN_LIMIT("%s: any_congested: nonexistent device %s",
  				     dm_device_name(t->md),

  				     bdevname(dd->dm_dev->bdev, b));

  	}

  	list_for_each_entry(cb, &t->target_callbacks, list)
  		if (cb->congested_fn)
  			r |= cb->congested_fn(cb, bdi_bits);

  	return r;
  }

  struct mapped_device *dm_table_get_md(struct dm_table *t)
  {

  	return t->md;
  }

  EXPORT_SYMBOL(dm_table_get_md);

  void dm_table_run_md_queue_async(struct dm_table *t)
  {
  	struct mapped_device *md;
  	struct request_queue *queue;
  	unsigned long flags;
  
  	if (!dm_table_request_based(t))
  		return;
  
  	md = dm_table_get_md(t);
  	queue = dm_get_md_queue(md);
  	if (queue) {

  		if (queue->mq_ops)
  			blk_mq_run_hw_queues(queue, true);
  		else {
  			spin_lock_irqsave(queue->queue_lock, flags);
  			blk_run_queue_async(queue);
  			spin_unlock_irqrestore(queue->queue_lock, flags);
  		}

  	}
  }
  EXPORT_SYMBOL(dm_table_run_md_queue_async);