linux/drivers/md/dm-table.c
Milan Broz 8757b7764f [PATCH] dm table: add target preresume
This patch adds a target preresume hook.

It is called before the targets are resumed and if it returns an error the
resume gets cancelled.

The crypt target will use this to indicate that it is unable to process I/O
because no encryption key has been supplied.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-03 08:04:15 -07:00

1035 lines
21 KiB
C

/*
* Copyright (C) 2001 Sistina Software (UK) Limited.
* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/namei.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <asm/atomic.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;
atomic_t holders;
/* 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;
/*
* Indicates the rw permissions for the new logical
* device. This should be a combination of FMODE_READ
* and FMODE_WRITE.
*/
int mode;
/* a list of devices used by this table */
struct list_head devices;
/*
* These are optimistic limits taken from all the
* targets, some targets will need smaller limits.
*/
struct io_restrictions limits;
/* events get handed up using this callback */
void (*event_fn)(void *);
void *event_context;
};
/*
* 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;
}
/*
* Returns the minimum that is _not_ zero, unless both are zero.
*/
#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
/*
* Combine two io_restrictions, always taking the lower value.
*/
static void combine_restrictions_low(struct io_restrictions *lhs,
struct io_restrictions *rhs)
{
lhs->max_sectors =
min_not_zero(lhs->max_sectors, rhs->max_sectors);
lhs->max_phys_segments =
min_not_zero(lhs->max_phys_segments, rhs->max_phys_segments);
lhs->max_hw_segments =
min_not_zero(lhs->max_hw_segments, rhs->max_hw_segments);
lhs->hardsect_size = max(lhs->hardsect_size, rhs->hardsect_size);
lhs->max_segment_size =
min_not_zero(lhs->max_segment_size, rhs->max_segment_size);
lhs->seg_boundary_mask =
min_not_zero(lhs->seg_boundary_mask, rhs->seg_boundary_mask);
lhs->no_cluster |= rhs->no_cluster;
}
/*
* 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 = vmalloc(size);
if (addr)
memset(addr, 0, size);
return addr;
}
/*
* 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;
int n = t->num_targets;
/*
* Allocate both the target array and offset array at once.
*/
n_highs = (sector_t *) dm_vcalloc(num, sizeof(struct dm_target) +
sizeof(sector_t));
if (!n_highs)
return -ENOMEM;
n_targets = (struct dm_target *) (n_highs + num);
if (n) {
memcpy(n_highs, t->highs, sizeof(*n_highs) * n);
memcpy(n_targets, t->targets, sizeof(*n_targets) * n);
}
memset(n_highs + n, -1, sizeof(*n_highs) * (num - n));
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, int mode,
unsigned num_targets, struct mapped_device *md)
{
struct dm_table *t = kmalloc(sizeof(*t), GFP_KERNEL);
if (!t)
return -ENOMEM;
memset(t, 0, sizeof(*t));
INIT_LIST_HEAD(&t->devices);
atomic_set(&t->holders, 1);
if (!num_targets)
num_targets = KEYS_PER_NODE;
num_targets = dm_round_up(num_targets, KEYS_PER_NODE);
if (alloc_targets(t, num_targets)) {
kfree(t);
t = NULL;
return -ENOMEM;
}
t->mode = mode;
t->md = md;
*result = t;
return 0;
}
int dm_create_error_table(struct dm_table **result, struct mapped_device *md)
{
struct dm_table *t;
sector_t dev_size = 1;
int r;
/*
* Find current size of device.
* Default to 1 sector if inactive.
*/
t = dm_get_table(md);
if (t) {
dev_size = dm_table_get_size(t);
dm_table_put(t);
}
r = dm_table_create(&t, FMODE_READ, 1, md);
if (r)
return r;
r = dm_table_add_target(t, "error", 0, dev_size, NULL);
if (r)
goto out;
r = dm_table_complete(t);
if (r)
goto out;
*result = t;
out:
if (r)
dm_table_put(t);
return r;
}
EXPORT_SYMBOL_GPL(dm_create_error_table);
static void free_devices(struct list_head *devices)
{
struct list_head *tmp, *next;
for (tmp = devices->next; tmp != devices; tmp = next) {
struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
next = tmp->next;
kfree(dd);
}
}
static void table_destroy(struct dm_table *t)
{
unsigned int i;
/* free the indexes (see dm_table_complete) */
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 */
if (t->devices.next != &t->devices) {
DMWARN("devices still present during destroy: "
"dm_table_remove_device calls missing");
free_devices(&t->devices);
}
kfree(t);
}
void dm_table_get(struct dm_table *t)
{
atomic_inc(&t->holders);
}
void dm_table_put(struct dm_table *t)
{
if (!t)
return;
if (atomic_dec_and_test(&t->holders))
table_destroy(t);
}
/*
* Checks to see if we need to extend highs or targets.
*/
static inline int check_space(struct dm_table *t)
{
if (t->num_targets >= t->num_allocated)
return alloc_targets(t, t->num_allocated * 2);
return 0;
}
/*
* Convert a device path to a dev_t.
*/
static int lookup_device(const char *path, dev_t *dev)
{
int r;
struct nameidata nd;
struct inode *inode;
if ((r = path_lookup(path, LOOKUP_FOLLOW, &nd)))
return r;
inode = nd.dentry->d_inode;
if (!inode) {
r = -ENOENT;
goto out;
}
if (!S_ISBLK(inode->i_mode)) {
r = -ENOTBLK;
goto out;
}
*dev = inode->i_rdev;
out:
path_release(&nd);
return r;
}
/*
* See if we've already got a device in the list.
*/
static struct dm_dev *find_device(struct list_head *l, dev_t dev)
{
struct dm_dev *dd;
list_for_each_entry (dd, l, list)
if (dd->bdev->bd_dev == dev)
return dd;
return NULL;
}
/*
* Open a device so we can use it as a map destination.
*/
static int open_dev(struct dm_dev *d, dev_t dev, struct mapped_device *md)
{
static char *_claim_ptr = "I belong to device-mapper";
struct block_device *bdev;
int r;
BUG_ON(d->bdev);
bdev = open_by_devnum(dev, d->mode);
if (IS_ERR(bdev))
return PTR_ERR(bdev);
r = bd_claim_by_disk(bdev, _claim_ptr, dm_disk(md));
if (r)
blkdev_put(bdev);
else
d->bdev = bdev;
return r;
}
/*
* Close a device that we've been using.
*/
static void close_dev(struct dm_dev *d, struct mapped_device *md)
{
if (!d->bdev)
return;
bd_release_from_disk(d->bdev, dm_disk(md));
blkdev_put(d->bdev);
d->bdev = NULL;
}
/*
* If possible (ie. blk_size[major] is set), this checks an area
* of a destination device is valid.
*/
static int check_device_area(struct dm_dev *dd, sector_t start, sector_t len)
{
sector_t dev_size;
dev_size = dd->bdev->bd_inode->i_size >> SECTOR_SHIFT;
return ((start < dev_size) && (len <= (dev_size - start)));
}
/*
* 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.
*/
static int upgrade_mode(struct dm_dev *dd, int new_mode, struct mapped_device *md)
{
int r;
struct dm_dev dd_copy;
dev_t dev = dd->bdev->bd_dev;
dd_copy = *dd;
dd->mode |= new_mode;
dd->bdev = NULL;
r = open_dev(dd, dev, md);
if (!r)
close_dev(&dd_copy, md);
else
*dd = dd_copy;
return r;
}
/*
* Add a device to the list, or just increment the usage count if
* it's already present.
*/
static int __table_get_device(struct dm_table *t, struct dm_target *ti,
const char *path, sector_t start, sector_t len,
int mode, struct dm_dev **result)
{
int r;
dev_t dev;
struct dm_dev *dd;
unsigned int major, minor;
BUG_ON(!t);
if (sscanf(path, "%u:%u", &major, &minor) == 2) {
/* Extract the major/minor numbers */
dev = MKDEV(major, minor);
if (MAJOR(dev) != major || MINOR(dev) != minor)
return -EOVERFLOW;
} else {
/* convert the path to a device */
if ((r = lookup_device(path, &dev)))
return r;
}
dd = find_device(&t->devices, dev);
if (!dd) {
dd = kmalloc(sizeof(*dd), GFP_KERNEL);
if (!dd)
return -ENOMEM;
dd->mode = mode;
dd->bdev = NULL;
if ((r = open_dev(dd, dev, t->md))) {
kfree(dd);
return r;
}
format_dev_t(dd->name, dev);
atomic_set(&dd->count, 0);
list_add(&dd->list, &t->devices);
} else if (dd->mode != (mode | dd->mode)) {
r = upgrade_mode(dd, mode, t->md);
if (r)
return r;
}
atomic_inc(&dd->count);
if (!check_device_area(dd, start, len)) {
DMWARN("device %s too small for target", path);
dm_put_device(ti, dd);
return -EINVAL;
}
*result = dd;
return 0;
}
int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
sector_t len, int mode, struct dm_dev **result)
{
int r = __table_get_device(ti->table, ti, path,
start, len, mode, result);
if (!r) {
request_queue_t *q = bdev_get_queue((*result)->bdev);
struct io_restrictions *rs = &ti->limits;
/*
* Combine the device limits low.
*
* FIXME: if we move an io_restriction struct
* into q this would just be a call to
* combine_restrictions_low()
*/
rs->max_sectors =
min_not_zero(rs->max_sectors, q->max_sectors);
/* FIXME: Device-Mapper on top of RAID-0 breaks because DM
* currently doesn't honor MD's merge_bvec_fn routine.
* In this case, we'll force DM to use PAGE_SIZE or
* smaller I/O, just to be safe. A better fix is in the
* works, but add this for the time being so it will at
* least operate correctly.
*/
if (q->merge_bvec_fn)
rs->max_sectors =
min_not_zero(rs->max_sectors,
(unsigned int) (PAGE_SIZE >> 9));
rs->max_phys_segments =
min_not_zero(rs->max_phys_segments,
q->max_phys_segments);
rs->max_hw_segments =
min_not_zero(rs->max_hw_segments, q->max_hw_segments);
rs->hardsect_size = max(rs->hardsect_size, q->hardsect_size);
rs->max_segment_size =
min_not_zero(rs->max_segment_size, q->max_segment_size);
rs->seg_boundary_mask =
min_not_zero(rs->seg_boundary_mask,
q->seg_boundary_mask);
rs->no_cluster |= !test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
}
return r;
}
/*
* Decrement a devices use count and remove it if necessary.
*/
void dm_put_device(struct dm_target *ti, struct dm_dev *dd)
{
if (atomic_dec_and_test(&dd->count)) {
close_dev(dd, ti->table->md);
list_del(&dd->list);
kfree(dd);
}
}
/*
* 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.
*/
static char **realloc_argv(unsigned *array_size, char **old_argv)
{
char **argv;
unsigned new_size;
new_size = *array_size ? *array_size * 2 : 64;
argv = kmalloc(new_size * sizeof(*argv), GFP_KERNEL);
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) {
start = end;
/* Skip whitespace */
while (*start && isspace(*start))
start++;
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;
}
static void check_for_valid_limits(struct io_restrictions *rs)
{
if (!rs->max_sectors)
rs->max_sectors = SAFE_MAX_SECTORS;
if (!rs->max_phys_segments)
rs->max_phys_segments = MAX_PHYS_SEGMENTS;
if (!rs->max_hw_segments)
rs->max_hw_segments = MAX_HW_SEGMENTS;
if (!rs->hardsect_size)
rs->hardsect_size = 1 << SECTOR_SHIFT;
if (!rs->max_segment_size)
rs->max_segment_size = MAX_SEGMENT_SIZE;
if (!rs->seg_boundary_mask)
rs->seg_boundary_mask = -1;
}
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 ((r = check_space(t)))
return r;
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;
}
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";
r = -EINVAL;
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;
/* FIXME: the plan is to combine high here and then have
* the merge fn apply the target level restrictions. */
combine_restrictions_low(&t->limits, &tgt->limits);
return 0;
bad:
DMERR("%s: %s: %s", dm_device_name(t->md), type, tgt->error);
dm_put_target_type(tgt->type);
return r;
}
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, total = 0; 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.
*/
int dm_table_complete(struct dm_table *t)
{
int r = 0;
unsigned int leaf_nodes;
check_for_valid_limits(&t->limits);
/* 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 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);
}
sector_t dm_table_get_size(struct dm_table *t)
{
return t->num_targets ? (t->highs[t->num_targets - 1] + 1) : 0;
}
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.
*/
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];
}
void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q)
{
/*
* Make sure we obey the optimistic sub devices
* restrictions.
*/
blk_queue_max_sectors(q, t->limits.max_sectors);
q->max_phys_segments = t->limits.max_phys_segments;
q->max_hw_segments = t->limits.max_hw_segments;
q->hardsect_size = t->limits.hardsect_size;
q->max_segment_size = t->limits.max_segment_size;
q->seg_boundary_mask = t->limits.seg_boundary_mask;
if (t->limits.no_cluster)
q->queue_flags &= ~(1 << QUEUE_FLAG_CLUSTER);
else
q->queue_flags |= (1 << QUEUE_FLAG_CLUSTER);
}
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;
}
int dm_table_get_mode(struct dm_table *t)
{
return t->mode;
}
static void suspend_targets(struct dm_table *t, unsigned postsuspend)
{
int i = t->num_targets;
struct dm_target *ti = t->targets;
while (i--) {
if (postsuspend) {
if (ti->type->postsuspend)
ti->type->postsuspend(ti);
} else if (ti->type->presuspend)
ti->type->presuspend(ti);
ti++;
}
}
void dm_table_presuspend_targets(struct dm_table *t)
{
if (!t)
return;
return suspend_targets(t, 0);
}
void dm_table_postsuspend_targets(struct dm_table *t)
{
if (!t)
return;
return suspend_targets(t, 1);
}
int dm_table_resume_targets(struct dm_table *t)
{
int i, r = 0;
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)
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;
}
int dm_table_any_congested(struct dm_table *t, int bdi_bits)
{
struct list_head *d, *devices;
int r = 0;
devices = dm_table_get_devices(t);
for (d = devices->next; d != devices; d = d->next) {
struct dm_dev *dd = list_entry(d, struct dm_dev, list);
request_queue_t *q = bdev_get_queue(dd->bdev);
r |= bdi_congested(&q->backing_dev_info, bdi_bits);
}
return r;
}
void dm_table_unplug_all(struct dm_table *t)
{
struct list_head *d, *devices = dm_table_get_devices(t);
for (d = devices->next; d != devices; d = d->next) {
struct dm_dev *dd = list_entry(d, struct dm_dev, list);
request_queue_t *q = bdev_get_queue(dd->bdev);
if (q->unplug_fn)
q->unplug_fn(q);
}
}
int dm_table_flush_all(struct dm_table *t)
{
struct list_head *d, *devices = dm_table_get_devices(t);
int ret = 0;
for (d = devices->next; d != devices; d = d->next) {
struct dm_dev *dd = list_entry(d, struct dm_dev, list);
request_queue_t *q = bdev_get_queue(dd->bdev);
int err;
if (!q->issue_flush_fn)
err = -EOPNOTSUPP;
else
err = q->issue_flush_fn(q, dd->bdev->bd_disk, NULL);
if (!ret)
ret = err;
}
return ret;
}
struct mapped_device *dm_table_get_md(struct dm_table *t)
{
dm_get(t->md);
return t->md;
}
EXPORT_SYMBOL(dm_vcalloc);
EXPORT_SYMBOL(dm_get_device);
EXPORT_SYMBOL(dm_put_device);
EXPORT_SYMBOL(dm_table_event);
EXPORT_SYMBOL(dm_table_get_size);
EXPORT_SYMBOL(dm_table_get_mode);
EXPORT_SYMBOL(dm_table_get_md);
EXPORT_SYMBOL(dm_table_put);
EXPORT_SYMBOL(dm_table_get);
EXPORT_SYMBOL(dm_table_unplug_all);
EXPORT_SYMBOL(dm_table_flush_all);