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dm-thin-metadata.c
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/*
* Copyright (C) 2011-2012 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm-thin-metadata.h"
#include "persistent-data/dm-btree.h"
#include "persistent-data/dm-space-map.h"
#include "persistent-data/dm-space-map-disk.h"
#include "persistent-data/dm-transaction-manager.h"
#include <linux/list.h>
#include <linux/device-mapper.h>
#include <linux/workqueue.h>
/*--------------------------------------------------------------------------
* As far as the metadata goes, there is:
*
* - A superblock in block zero, taking up fewer than 512 bytes for
* atomic writes.
*
* - A space map managing the metadata blocks.
*
* - A space map managing the data blocks.
*
* - A btree mapping our internal thin dev ids onto struct disk_device_details.
*
* - A hierarchical btree, with 2 levels which effectively maps (thin
* dev id, virtual block) -> block_time. Block time is a 64-bit
* field holding the time in the low 24 bits, and block in the top 48
* bits.
*
* BTrees consist solely of btree_nodes, that fill a block. Some are
* internal nodes, as such their values are a __le64 pointing to other
* nodes. Leaf nodes can store data of any reasonable size (ie. much
* smaller than the block size). The nodes consist of the header,
* followed by an array of keys, followed by an array of values. We have
* to binary search on the keys so they're all held together to help the
* cpu cache.
*
* Space maps have 2 btrees:
*
* - One maps a uint64_t onto a struct index_entry. Which points to a
* bitmap block, and has some details about how many free entries there
* are etc.
*
* - The bitmap blocks have a header (for the checksum). Then the rest
* of the block is pairs of bits. With the meaning being:
*
* 0 - ref count is 0
* 1 - ref count is 1
* 2 - ref count is 2
* 3 - ref count is higher than 2
*
* - If the count is higher than 2 then the ref count is entered in a
* second btree that directly maps the block_address to a uint32_t ref
* count.
*
* The space map metadata variant doesn't have a bitmaps btree. Instead
* it has one single blocks worth of index_entries. This avoids
* recursive issues with the bitmap btree needing to allocate space in
* order to insert. With a small data block size such as 64k the
* metadata support data devices that are hundreds of terrabytes.
*
* The space maps allocate space linearly from front to back. Space that
* is freed in a transaction is never recycled within that transaction.
* To try and avoid fragmenting _free_ space the allocator always goes
* back and fills in gaps.
*
* All metadata io is in THIN_METADATA_BLOCK_SIZE sized/aligned chunks
* from the block manager.
*--------------------------------------------------------------------------*/
#define DM_MSG_PREFIX "thin metadata"
#define THIN_SUPERBLOCK_MAGIC 27022010
#define THIN_SUPERBLOCK_LOCATION 0
#define THIN_VERSION 2
#define SECTOR_TO_BLOCK_SHIFT 3
/*
* For btree insert:
* 3 for btree insert +
* 2 for btree lookup used within space map
* For btree remove:
* 2 for shadow spine +
* 4 for rebalance 3 child node
*/
#define THIN_MAX_CONCURRENT_LOCKS 6
/* This should be plenty */
#define SPACE_MAP_ROOT_SIZE 128
/*
* Little endian on-disk superblock and device details.
*/
struct thin_disk_superblock {
__le32 csum; /* Checksum of superblock except for this field. */
__le32 flags;
__le64 blocknr; /* This block number, dm_block_t. */
__u8 uuid[16];
__le64 magic;
__le32 version;
__le32 time;
__le64 trans_id;
/*
* Root held by userspace transactions.
*/
__le64 held_root;
__u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
/*
* 2-level btree mapping (dev_id, (dev block, time)) -> data block
*/
__le64 data_mapping_root;
/*
* Device detail root mapping dev_id -> device_details
*/
__le64 device_details_root;
__le32 data_block_size; /* In 512-byte sectors. */
__le32 metadata_block_size; /* In 512-byte sectors. */
__le64 metadata_nr_blocks;
__le32 compat_flags;
__le32 compat_ro_flags;
__le32 incompat_flags;
} __packed;
struct disk_device_details {
__le64 mapped_blocks;
__le64 transaction_id; /* When created. */
__le32 creation_time;
__le32 snapshotted_time;
} __packed;
struct dm_pool_metadata {
struct hlist_node hash;
struct block_device *bdev;
struct dm_block_manager *bm;
struct dm_space_map *metadata_sm;
struct dm_space_map *data_sm;
struct dm_transaction_manager *tm;
struct dm_transaction_manager *nb_tm;
/*
* Two-level btree.
* First level holds thin_dev_t.
* Second level holds mappings.
*/
struct dm_btree_info info;
/*
* Non-blocking version of the above.
*/
struct dm_btree_info nb_info;
/*
* Just the top level for deleting whole devices.
*/
struct dm_btree_info tl_info;
/*
* Just the bottom level for creating new devices.
*/
struct dm_btree_info bl_info;
/*
* Describes the device details btree.
*/
struct dm_btree_info details_info;
struct rw_semaphore root_lock;
uint32_t time;
dm_block_t root;
dm_block_t details_root;
struct list_head thin_devices;
uint64_t trans_id;
unsigned long flags;
sector_t data_block_size;
/*
* Set if a transaction has to be aborted but the attempt to roll back
* to the previous (good) transaction failed. The only pool metadata
* operation possible in this state is the closing of the device.
*/
bool fail_io:1;
/*
* Reading the space map roots can fail, so we read it into these
* buffers before the superblock is locked and updated.
*/
__u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
};
struct dm_thin_device {
struct list_head list;
struct dm_pool_metadata *pmd;
dm_thin_id id;
int open_count;
bool changed:1;
bool aborted_with_changes:1;
uint64_t mapped_blocks;
uint64_t transaction_id;
uint32_t creation_time;
uint32_t snapshotted_time;
};
/*----------------------------------------------------------------
* superblock validator
*--------------------------------------------------------------*/
#define SUPERBLOCK_CSUM_XOR 160774
static void sb_prepare_for_write(struct dm_block_validator *v,
struct dm_block *b,
size_t block_size)
{
struct thin_disk_superblock *disk_super = dm_block_data(b);
disk_super->blocknr = cpu_to_le64(dm_block_location(b));
disk_super->csum = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
block_size - sizeof(__le32),
SUPERBLOCK_CSUM_XOR));
}
static int sb_check(struct dm_block_validator *v,
struct dm_block *b,
size_t block_size)
{
struct thin_disk_superblock *disk_super = dm_block_data(b);
__le32 csum_le;
if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
DMERR("sb_check failed: blocknr %llu: "
"wanted %llu", le64_to_cpu(disk_super->blocknr),
(unsigned long long)dm_block_location(b));
return -ENOTBLK;
}
if (le64_to_cpu(disk_super->magic) != THIN_SUPERBLOCK_MAGIC) {
DMERR("sb_check failed: magic %llu: "
"wanted %llu", le64_to_cpu(disk_super->magic),
(unsigned long long)THIN_SUPERBLOCK_MAGIC);
return -EILSEQ;
}
csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
block_size - sizeof(__le32),
SUPERBLOCK_CSUM_XOR));
if (csum_le != disk_super->csum) {
DMERR("sb_check failed: csum %u: wanted %u",
le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
return -EILSEQ;
}
return 0;
}
static struct dm_block_validator sb_validator = {
.name = "superblock",
.prepare_for_write = sb_prepare_for_write,
.check = sb_check
};
/*----------------------------------------------------------------
* Methods for the btree value types
*--------------------------------------------------------------*/
static uint64_t pack_block_time(dm_block_t b, uint32_t t)
{
return (b << 24) | t;
}
static void unpack_block_time(uint64_t v, dm_block_t *b, uint32_t *t)
{
*b = v >> 24;
*t = v & ((1 << 24) - 1);
}
static void data_block_inc(void *context, const void *value_le)
{
struct dm_space_map *sm = context;
__le64 v_le;
uint64_t b;
uint32_t t;
memcpy(&v_le, value_le, sizeof(v_le));
unpack_block_time(le64_to_cpu(v_le), &b, &t);
dm_sm_inc_block(sm, b);
}
static void data_block_dec(void *context, const void *value_le)
{
struct dm_space_map *sm = context;
__le64 v_le;
uint64_t b;
uint32_t t;
memcpy(&v_le, value_le, sizeof(v_le));
unpack_block_time(le64_to_cpu(v_le), &b, &t);
dm_sm_dec_block(sm, b);
}
static int data_block_equal(void *context, const void *value1_le, const void *value2_le)
{
__le64 v1_le, v2_le;
uint64_t b1, b2;
uint32_t t;
memcpy(&v1_le, value1_le, sizeof(v1_le));
memcpy(&v2_le, value2_le, sizeof(v2_le));
unpack_block_time(le64_to_cpu(v1_le), &b1, &t);
unpack_block_time(le64_to_cpu(v2_le), &b2, &t);
return b1 == b2;
}
static void subtree_inc(void *context, const void *value)
{
struct dm_btree_info *info = context;
__le64 root_le;
uint64_t root;
memcpy(&root_le, value, sizeof(root_le));
root = le64_to_cpu(root_le);
dm_tm_inc(info->tm, root);
}
static void subtree_dec(void *context, const void *value)
{
struct dm_btree_info *info = context;
__le64 root_le;
uint64_t root;
memcpy(&root_le, value, sizeof(root_le));
root = le64_to_cpu(root_le);
if (dm_btree_del(info, root))
DMERR("btree delete failed");
}
static int subtree_equal(void *context, const void *value1_le, const void *value2_le)
{
__le64 v1_le, v2_le;
memcpy(&v1_le, value1_le, sizeof(v1_le));
memcpy(&v2_le, value2_le, sizeof(v2_le));
return v1_le == v2_le;
}
/*----------------------------------------------------------------*/
static int superblock_lock_zero(struct dm_pool_metadata *pmd,
struct dm_block **sblock)
{
return dm_bm_write_lock_zero(pmd->bm, THIN_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
static int superblock_lock(struct dm_pool_metadata *pmd,
struct dm_block **sblock)
{
return dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
static int __superblock_all_zeroes(struct dm_block_manager *bm, int *result)
{
int r;
unsigned i;
struct dm_block *b;
__le64 *data_le, zero = cpu_to_le64(0);
unsigned block_size = dm_bm_block_size(bm) / sizeof(__le64);
/*
* We can't use a validator here - it may be all zeroes.
*/
r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION, NULL, &b);
if (r)
return r;
data_le = dm_block_data(b);
*result = 1;
for (i = 0; i < block_size; i++) {
if (data_le[i] != zero) {
*result = 0;
break;
}
}
dm_bm_unlock(b);
return 0;
}
static void __setup_btree_details(struct dm_pool_metadata *pmd)
{
pmd->info.tm = pmd->tm;
pmd->info.levels = 2;
pmd->info.value_type.context = pmd->data_sm;
pmd->info.value_type.size = sizeof(__le64);
pmd->info.value_type.inc = data_block_inc;
pmd->info.value_type.dec = data_block_dec;
pmd->info.value_type.equal = data_block_equal;
memcpy(&pmd->nb_info, &pmd->info, sizeof(pmd->nb_info));
pmd->nb_info.tm = pmd->nb_tm;
pmd->tl_info.tm = pmd->tm;
pmd->tl_info.levels = 1;
pmd->tl_info.value_type.context = &pmd->bl_info;
pmd->tl_info.value_type.size = sizeof(__le64);
pmd->tl_info.value_type.inc = subtree_inc;
pmd->tl_info.value_type.dec = subtree_dec;
pmd->tl_info.value_type.equal = subtree_equal;
pmd->bl_info.tm = pmd->tm;
pmd->bl_info.levels = 1;
pmd->bl_info.value_type.context = pmd->data_sm;
pmd->bl_info.value_type.size = sizeof(__le64);
pmd->bl_info.value_type.inc = data_block_inc;
pmd->bl_info.value_type.dec = data_block_dec;
pmd->bl_info.value_type.equal = data_block_equal;
pmd->details_info.tm = pmd->tm;
pmd->details_info.levels = 1;
pmd->details_info.value_type.context = NULL;
pmd->details_info.value_type.size = sizeof(struct disk_device_details);
pmd->details_info.value_type.inc = NULL;
pmd->details_info.value_type.dec = NULL;
pmd->details_info.value_type.equal = NULL;
}
static int save_sm_roots(struct dm_pool_metadata *pmd)
{
int r;
size_t len;
r = dm_sm_root_size(pmd->metadata_sm, &len);
if (r < 0)
return r;
r = dm_sm_copy_root(pmd->metadata_sm, &pmd->metadata_space_map_root, len);
if (r < 0)
return r;
r = dm_sm_root_size(pmd->data_sm, &len);
if (r < 0)
return r;
return dm_sm_copy_root(pmd->data_sm, &pmd->data_space_map_root, len);
}
static void copy_sm_roots(struct dm_pool_metadata *pmd,
struct thin_disk_superblock *disk)
{
memcpy(&disk->metadata_space_map_root,
&pmd->metadata_space_map_root,
sizeof(pmd->metadata_space_map_root));
memcpy(&disk->data_space_map_root,
&pmd->data_space_map_root,
sizeof(pmd->data_space_map_root));
}
static int __write_initial_superblock(struct dm_pool_metadata *pmd)
{
int r;
struct dm_block *sblock;
struct thin_disk_superblock *disk_super;
sector_t bdev_size = i_size_read(pmd->bdev->bd_inode) >> SECTOR_SHIFT;
if (bdev_size > THIN_METADATA_MAX_SECTORS)
bdev_size = THIN_METADATA_MAX_SECTORS;
r = dm_sm_commit(pmd->data_sm);
if (r < 0)
return r;
r = dm_tm_pre_commit(pmd->tm);
if (r < 0)
return r;
r = save_sm_roots(pmd);
if (r < 0)
return r;
r = superblock_lock_zero(pmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
disk_super->flags = 0;
memset(disk_super->uuid, 0, sizeof(disk_super->uuid));
disk_super->magic = cpu_to_le64(THIN_SUPERBLOCK_MAGIC);
disk_super->version = cpu_to_le32(THIN_VERSION);
disk_super->time = 0;
disk_super->trans_id = 0;
disk_super->held_root = 0;
copy_sm_roots(pmd, disk_super);
disk_super->data_mapping_root = cpu_to_le64(pmd->root);
disk_super->device_details_root = cpu_to_le64(pmd->details_root);
disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE);
disk_super->metadata_nr_blocks = cpu_to_le64(bdev_size >> SECTOR_TO_BLOCK_SHIFT);
disk_super->data_block_size = cpu_to_le32(pmd->data_block_size);
return dm_tm_commit(pmd->tm, sblock);
}
static int __format_metadata(struct dm_pool_metadata *pmd)
{
int r;
r = dm_tm_create_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
&pmd->tm, &pmd->metadata_sm);
if (r < 0) {
DMERR("tm_create_with_sm failed");
return r;
}
pmd->data_sm = dm_sm_disk_create(pmd->tm, 0);
if (IS_ERR(pmd->data_sm)) {
DMERR("sm_disk_create failed");
r = PTR_ERR(pmd->data_sm);
goto bad_cleanup_tm;
}
pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
if (!pmd->nb_tm) {
DMERR("could not create non-blocking clone tm");
r = -ENOMEM;
goto bad_cleanup_data_sm;
}
__setup_btree_details(pmd);
r = dm_btree_empty(&pmd->info, &pmd->root);
if (r < 0)
goto bad_cleanup_nb_tm;
r = dm_btree_empty(&pmd->details_info, &pmd->details_root);
if (r < 0) {
DMERR("couldn't create devices root");
goto bad_cleanup_nb_tm;
}
r = __write_initial_superblock(pmd);
if (r)
goto bad_cleanup_nb_tm;
return 0;
bad_cleanup_nb_tm:
dm_tm_destroy(pmd->nb_tm);
bad_cleanup_data_sm:
dm_sm_destroy(pmd->data_sm);
bad_cleanup_tm:
dm_tm_destroy(pmd->tm);
dm_sm_destroy(pmd->metadata_sm);
return r;
}
static int __check_incompat_features(struct thin_disk_superblock *disk_super,
struct dm_pool_metadata *pmd)
{
uint32_t features;
features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
if (features) {
DMERR("could not access metadata due to unsupported optional features (%lx).",
(unsigned long)features);
return -EINVAL;
}
/*
* Check for read-only metadata to skip the following RDWR checks.
*/
if (get_disk_ro(pmd->bdev->bd_disk))
return 0;
features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
if (features) {
DMERR("could not access metadata RDWR due to unsupported optional features (%lx).",
(unsigned long)features);
return -EINVAL;
}
return 0;
}
static int __open_metadata(struct dm_pool_metadata *pmd)
{
int r;
struct dm_block *sblock;
struct thin_disk_superblock *disk_super;
r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
&sb_validator, &sblock);
if (r < 0) {
DMERR("couldn't read superblock");
return r;
}
disk_super = dm_block_data(sblock);
/* Verify the data block size hasn't changed */
if (le32_to_cpu(disk_super->data_block_size) != pmd->data_block_size) {
DMERR("changing the data block size (from %u to %llu) is not supported",
le32_to_cpu(disk_super->data_block_size),
(unsigned long long)pmd->data_block_size);
r = -EINVAL;
goto bad_unlock_sblock;
}
r = __check_incompat_features(disk_super, pmd);
if (r < 0)
goto bad_unlock_sblock;
r = dm_tm_open_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
disk_super->metadata_space_map_root,
sizeof(disk_super->metadata_space_map_root),
&pmd->tm, &pmd->metadata_sm);
if (r < 0) {
DMERR("tm_open_with_sm failed");
goto bad_unlock_sblock;
}
pmd->data_sm = dm_sm_disk_open(pmd->tm, disk_super->data_space_map_root,
sizeof(disk_super->data_space_map_root));
if (IS_ERR(pmd->data_sm)) {
DMERR("sm_disk_open failed");
r = PTR_ERR(pmd->data_sm);
goto bad_cleanup_tm;
}
pmd->nb_tm = dm_tm_create_non_blocking_clone(pmd->tm);
if (!pmd->nb_tm) {
DMERR("could not create non-blocking clone tm");
r = -ENOMEM;
goto bad_cleanup_data_sm;
}
__setup_btree_details(pmd);
dm_bm_unlock(sblock);
return 0;
bad_cleanup_data_sm:
dm_sm_destroy(pmd->data_sm);
bad_cleanup_tm:
dm_tm_destroy(pmd->tm);
dm_sm_destroy(pmd->metadata_sm);
bad_unlock_sblock:
dm_bm_unlock(sblock);
return r;
}
static int __open_or_format_metadata(struct dm_pool_metadata *pmd, bool format_device)
{
int r, unformatted;
r = __superblock_all_zeroes(pmd->bm, &unformatted);
if (r)
return r;
if (unformatted)
return format_device ? __format_metadata(pmd) : -EPERM;
return __open_metadata(pmd);
}
static int __create_persistent_data_objects(struct dm_pool_metadata *pmd, bool format_device)
{
int r;
pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
THIN_MAX_CONCURRENT_LOCKS);
if (IS_ERR(pmd->bm)) {
DMERR("could not create block manager");
return PTR_ERR(pmd->bm);
}
r = __open_or_format_metadata(pmd, format_device);
if (r)
dm_block_manager_destroy(pmd->bm);
return r;
}
static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd)
{
dm_sm_destroy(pmd->data_sm);
dm_sm_destroy(pmd->metadata_sm);
dm_tm_destroy(pmd->nb_tm);
dm_tm_destroy(pmd->tm);
dm_block_manager_destroy(pmd->bm);
}
static int __begin_transaction(struct dm_pool_metadata *pmd)
{
int r;
struct thin_disk_superblock *disk_super;
struct dm_block *sblock;
/*
* We re-read the superblock every time. Shouldn't need to do this
* really.
*/
r = dm_bm_read_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
&sb_validator, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
pmd->time = le32_to_cpu(disk_super->time);
pmd->root = le64_to_cpu(disk_super->data_mapping_root);
pmd->details_root = le64_to_cpu(disk_super->device_details_root);
pmd->trans_id = le64_to_cpu(disk_super->trans_id);
pmd->flags = le32_to_cpu(disk_super->flags);
pmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
dm_bm_unlock(sblock);
return 0;
}
static int __write_changed_details(struct dm_pool_metadata *pmd)
{
int r;
struct dm_thin_device *td, *tmp;
struct disk_device_details details;
uint64_t key;
list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
if (!td->changed)
continue;
key = td->id;
details.mapped_blocks = cpu_to_le64(td->mapped_blocks);
details.transaction_id = cpu_to_le64(td->transaction_id);
details.creation_time = cpu_to_le32(td->creation_time);
details.snapshotted_time = cpu_to_le32(td->snapshotted_time);
__dm_bless_for_disk(&details);
r = dm_btree_insert(&pmd->details_info, pmd->details_root,
&key, &details, &pmd->details_root);
if (r)
return r;
if (td->open_count)
td->changed = 0;
else {
list_del(&td->list);
kfree(td);
}
}
return 0;
}
static int __commit_transaction(struct dm_pool_metadata *pmd)
{
int r;
size_t metadata_len, data_len;
struct thin_disk_superblock *disk_super;
struct dm_block *sblock;
/*
* We need to know if the thin_disk_superblock exceeds a 512-byte sector.
*/
BUILD_BUG_ON(sizeof(struct thin_disk_superblock) > 512);
r = __write_changed_details(pmd);
if (r < 0)
return r;
r = dm_sm_commit(pmd->data_sm);
if (r < 0)
return r;
r = dm_tm_pre_commit(pmd->tm);
if (r < 0)
return r;
r = dm_sm_root_size(pmd->metadata_sm, &metadata_len);
if (r < 0)
return r;
r = dm_sm_root_size(pmd->data_sm, &data_len);
if (r < 0)
return r;
r = save_sm_roots(pmd);
if (r < 0)
return r;
r = superblock_lock(pmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
disk_super->time = cpu_to_le32(pmd->time);
disk_super->data_mapping_root = cpu_to_le64(pmd->root);
disk_super->device_details_root = cpu_to_le64(pmd->details_root);
disk_super->trans_id = cpu_to_le64(pmd->trans_id);
disk_super->flags = cpu_to_le32(pmd->flags);
copy_sm_roots(pmd, disk_super);
return dm_tm_commit(pmd->tm, sblock);
}
struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
sector_t data_block_size,
bool format_device)
{
int r;
struct dm_pool_metadata *pmd;
pmd = kmalloc(sizeof(*pmd), GFP_KERNEL);
if (!pmd) {
DMERR("could not allocate metadata struct");
return ERR_PTR(-ENOMEM);
}
init_rwsem(&pmd->root_lock);
pmd->time = 0;
INIT_LIST_HEAD(&pmd->thin_devices);
pmd->fail_io = false;
pmd->bdev = bdev;
pmd->data_block_size = data_block_size;
r = __create_persistent_data_objects(pmd, format_device);
if (r) {
kfree(pmd);
return ERR_PTR(r);
}
r = __begin_transaction(pmd);
if (r < 0) {
if (dm_pool_metadata_close(pmd) < 0)
DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
return ERR_PTR(r);
}
return pmd;
}
int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
{
int r;
unsigned open_devices = 0;
struct dm_thin_device *td, *tmp;
down_read(&pmd->root_lock);
list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
if (td->open_count)
open_devices++;
else {
list_del(&td->list);
kfree(td);
}
}
up_read(&pmd->root_lock);
if (open_devices) {
DMERR("attempt to close pmd when %u device(s) are still open",
open_devices);
return -EBUSY;
}
if (!dm_bm_is_read_only(pmd->bm) && !pmd->fail_io) {
r = __commit_transaction(pmd);
if (r < 0)
DMWARN("%s: __commit_transaction() failed, error = %d",
__func__, r);
}
if (!pmd->fail_io)
__destroy_persistent_data_objects(pmd);
kfree(pmd);
return 0;
}
/*
* __open_device: Returns @td corresponding to device with id @dev,
* creating it if @create is set and incrementing @td->open_count.
* On failure, @td is undefined.
*/
static int __open_device(struct dm_pool_metadata *pmd,
dm_thin_id dev, int create,
struct dm_thin_device **td)
{
int r, changed = 0;
struct dm_thin_device *td2;
uint64_t key = dev;
struct disk_device_details details_le;
/*
* If the device is already open, return it.
*/
list_for_each_entry(td2, &pmd->thin_devices, list)
if (td2->id == dev) {
/*
* May not create an already-open device.
*/
if (create)
return -EEXIST;
td2->open_count++;
*td = td2;
return 0;
}
/*
* Check the device exists.
*/
r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
&key, &details_le);
if (r) {
if (r != -ENODATA || !create)
return r;
/*
* Create new device.
*/
changed = 1;
details_le.mapped_blocks = 0;
details_le.transaction_id = cpu_to_le64(pmd->trans_id);
details_le.creation_time = cpu_to_le32(pmd->time);
details_le.snapshotted_time = cpu_to_le32(pmd->time);
}
*td = kmalloc(sizeof(**td), GFP_NOIO);
if (!*td)
return -ENOMEM;
(*td)->pmd = pmd;
(*td)->id = dev;
(*td)->open_count = 1;
(*td)->changed = changed;
(*td)->aborted_with_changes = false;
(*td)->mapped_blocks = le64_to_cpu(details_le.mapped_blocks);
(*td)->transaction_id = le64_to_cpu(details_le.transaction_id);
(*td)->creation_time = le32_to_cpu(details_le.creation_time);
(*td)->snapshotted_time = le32_to_cpu(details_le.snapshotted_time);
list_add(&(*td)->list, &pmd->thin_devices);
return 0;
}
static void __close_device(struct dm_thin_device *td)
{
--td->open_count;
}
static int __create_thin(struct dm_pool_metadata *pmd,
dm_thin_id dev)
{
int r;
dm_block_t dev_root;
uint64_t key = dev;
struct disk_device_details details_le;
struct dm_thin_device *td;
__le64 value;
r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
&key, &details_le);
if (!r)
return -EEXIST;
/*
* Create an empty btree for the mappings.
*/
r = dm_btree_empty(&pmd->bl_info, &dev_root);
if (r)
return r;
/*
* Insert it into the main mapping tree.
*/
value = cpu_to_le64(dev_root);
__dm_bless_for_disk(&value);