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dm-cache-metadata.c
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/*
* Copyright (C) 2012 Red Hat, Inc.
*
* This file is released under the GPL.
*/
#include "dm-cache-metadata.h"
#include "persistent-data/dm-array.h"
#include "persistent-data/dm-bitset.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/device-mapper.h>
#include <linux/refcount.h>
/*----------------------------------------------------------------*/
#define DM_MSG_PREFIX "cache metadata"
#define CACHE_SUPERBLOCK_MAGIC 06142003
#define CACHE_SUPERBLOCK_LOCATION 0
/*
* defines a range of metadata versions that this module can handle.
*/
#define MIN_CACHE_VERSION 1
#define MAX_CACHE_VERSION 2
/*
* 3 for btree insert +
* 2 for btree lookup used within space map
*/
#define CACHE_MAX_CONCURRENT_LOCKS 5
#define SPACE_MAP_ROOT_SIZE 128
enum superblock_flag_bits {
/* for spotting crashes that would invalidate the dirty bitset */
CLEAN_SHUTDOWN,
/* metadata must be checked using the tools */
NEEDS_CHECK,
};
/*
* Each mapping from cache block -> origin block carries a set of flags.
*/
enum mapping_bits {
/*
* A valid mapping. Because we're using an array we clear this
* flag for an non existant mapping.
*/
M_VALID = 1,
/*
* The data on the cache is different from that on the origin.
* This flag is only used by metadata format 1.
*/
M_DIRTY = 2
};
struct cache_disk_superblock {
__le32 csum;
__le32 flags;
__le64 blocknr;
__u8 uuid[16];
__le64 magic;
__le32 version;
__u8 policy_name[CACHE_POLICY_NAME_SIZE];
__le32 policy_hint_size;
__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
__le64 mapping_root;
__le64 hint_root;
__le64 discard_root;
__le64 discard_block_size;
__le64 discard_nr_blocks;
__le32 data_block_size;
__le32 metadata_block_size;
__le32 cache_blocks;
__le32 compat_flags;
__le32 compat_ro_flags;
__le32 incompat_flags;
__le32 read_hits;
__le32 read_misses;
__le32 write_hits;
__le32 write_misses;
__le32 policy_version[CACHE_POLICY_VERSION_SIZE];
/*
* Metadata format 2 fields.
*/
__le64 dirty_root;
} __packed;
struct dm_cache_metadata {
refcount_t ref_count;
struct list_head list;
unsigned version;
struct block_device *bdev;
struct dm_block_manager *bm;
struct dm_space_map *metadata_sm;
struct dm_transaction_manager *tm;
struct dm_array_info info;
struct dm_array_info hint_info;
struct dm_disk_bitset discard_info;
struct rw_semaphore root_lock;
unsigned long flags;
dm_block_t root;
dm_block_t hint_root;
dm_block_t discard_root;
sector_t discard_block_size;
dm_dblock_t discard_nr_blocks;
sector_t data_block_size;
dm_cblock_t cache_blocks;
bool changed:1;
bool clean_when_opened:1;
char policy_name[CACHE_POLICY_NAME_SIZE];
unsigned policy_version[CACHE_POLICY_VERSION_SIZE];
size_t policy_hint_size;
struct dm_cache_statistics stats;
/*
* Reading the space map root can fail, so we read it into this
* buffer before the superblock is locked and updated.
*/
__u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
/*
* Set if a transaction has to be aborted but the attempt to roll
* back to the previous (good) transaction failed. The only
* metadata operation permissible in this state is the closing of
* the device.
*/
bool fail_io:1;
/*
* Metadata format 2 fields.
*/
dm_block_t dirty_root;
struct dm_disk_bitset dirty_info;
/*
* These structures are used when loading metadata. They're too
* big to put on the stack.
*/
struct dm_array_cursor mapping_cursor;
struct dm_array_cursor hint_cursor;
struct dm_bitset_cursor dirty_cursor;
};
/*-------------------------------------------------------------------
* superblock validator
*-----------------------------------------------------------------*/
#define SUPERBLOCK_CSUM_XOR 9031977
static void sb_prepare_for_write(struct dm_block_validator *v,
struct dm_block *b,
size_t sb_block_size)
{
struct cache_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,
sb_block_size - sizeof(__le32),
SUPERBLOCK_CSUM_XOR));
}
static int check_metadata_version(struct cache_disk_superblock *disk_super)
{
uint32_t metadata_version = le32_to_cpu(disk_super->version);
if (metadata_version < MIN_CACHE_VERSION || metadata_version > MAX_CACHE_VERSION) {
DMERR("Cache metadata version %u found, but only versions between %u and %u supported.",
metadata_version, MIN_CACHE_VERSION, MAX_CACHE_VERSION);
return -EINVAL;
}
return 0;
}
static int sb_check(struct dm_block_validator *v,
struct dm_block *b,
size_t sb_block_size)
{
struct cache_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) != CACHE_SUPERBLOCK_MAGIC) {
DMERR("sb_check failed: magic %llu: wanted %llu",
le64_to_cpu(disk_super->magic),
(unsigned long long)CACHE_SUPERBLOCK_MAGIC);
return -EILSEQ;
}
csum_le = cpu_to_le32(dm_bm_checksum(&disk_super->flags,
sb_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 check_metadata_version(disk_super);
}
static struct dm_block_validator sb_validator = {
.name = "superblock",
.prepare_for_write = sb_prepare_for_write,
.check = sb_check
};
/*----------------------------------------------------------------*/
static int superblock_read_lock(struct dm_cache_metadata *cmd,
struct dm_block **sblock)
{
return dm_bm_read_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
static int superblock_lock_zero(struct dm_cache_metadata *cmd,
struct dm_block **sblock)
{
return dm_bm_write_lock_zero(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
static int superblock_lock(struct dm_cache_metadata *cmd,
struct dm_block **sblock)
{
return dm_bm_write_lock(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&sb_validator, sblock);
}
/*----------------------------------------------------------------*/
static int __superblock_all_zeroes(struct dm_block_manager *bm, bool *result)
{
int r;
unsigned i;
struct dm_block *b;
__le64 *data_le, zero = cpu_to_le64(0);
unsigned sb_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, CACHE_SUPERBLOCK_LOCATION, NULL, &b);
if (r)
return r;
data_le = dm_block_data(b);
*result = true;
for (i = 0; i < sb_block_size; i++) {
if (data_le[i] != zero) {
*result = false;
break;
}
}
dm_bm_unlock(b);
return 0;
}
static void __setup_mapping_info(struct dm_cache_metadata *cmd)
{
struct dm_btree_value_type vt;
vt.context = NULL;
vt.size = sizeof(__le64);
vt.inc = NULL;
vt.dec = NULL;
vt.equal = NULL;
dm_array_info_init(&cmd->info, cmd->tm, &vt);
if (cmd->policy_hint_size) {
vt.size = sizeof(__le32);
dm_array_info_init(&cmd->hint_info, cmd->tm, &vt);
}
}
static int __save_sm_root(struct dm_cache_metadata *cmd)
{
int r;
size_t metadata_len;
r = dm_sm_root_size(cmd->metadata_sm, &metadata_len);
if (r < 0)
return r;
return dm_sm_copy_root(cmd->metadata_sm, &cmd->metadata_space_map_root,
metadata_len);
}
static void __copy_sm_root(struct dm_cache_metadata *cmd,
struct cache_disk_superblock *disk_super)
{
memcpy(&disk_super->metadata_space_map_root,
&cmd->metadata_space_map_root,
sizeof(cmd->metadata_space_map_root));
}
static bool separate_dirty_bits(struct dm_cache_metadata *cmd)
{
return cmd->version >= 2;
}
static int __write_initial_superblock(struct dm_cache_metadata *cmd)
{
int r;
struct dm_block *sblock;
struct cache_disk_superblock *disk_super;
sector_t bdev_size = bdev_nr_sectors(cmd->bdev);
/* FIXME: see if we can lose the max sectors limit */
if (bdev_size > DM_CACHE_METADATA_MAX_SECTORS)
bdev_size = DM_CACHE_METADATA_MAX_SECTORS;
r = dm_tm_pre_commit(cmd->tm);
if (r < 0)
return r;
/*
* dm_sm_copy_root() can fail. So we need to do it before we start
* updating the superblock.
*/
r = __save_sm_root(cmd);
if (r)
return r;
r = superblock_lock_zero(cmd, &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(CACHE_SUPERBLOCK_MAGIC);
disk_super->version = cpu_to_le32(cmd->version);
memset(disk_super->policy_name, 0, sizeof(disk_super->policy_name));
memset(disk_super->policy_version, 0, sizeof(disk_super->policy_version));
disk_super->policy_hint_size = cpu_to_le32(0);
__copy_sm_root(cmd, disk_super);
disk_super->mapping_root = cpu_to_le64(cmd->root);
disk_super->hint_root = cpu_to_le64(cmd->hint_root);
disk_super->discard_root = cpu_to_le64(cmd->discard_root);
disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE);
disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
disk_super->cache_blocks = cpu_to_le32(0);
disk_super->read_hits = cpu_to_le32(0);
disk_super->read_misses = cpu_to_le32(0);
disk_super->write_hits = cpu_to_le32(0);
disk_super->write_misses = cpu_to_le32(0);
if (separate_dirty_bits(cmd))
disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
return dm_tm_commit(cmd->tm, sblock);
}
static int __format_metadata(struct dm_cache_metadata *cmd)
{
int r;
r = dm_tm_create_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
&cmd->tm, &cmd->metadata_sm);
if (r < 0) {
DMERR("tm_create_with_sm failed");
return r;
}
__setup_mapping_info(cmd);
r = dm_array_empty(&cmd->info, &cmd->root);
if (r < 0)
goto bad;
if (separate_dirty_bits(cmd)) {
dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
r = dm_bitset_empty(&cmd->dirty_info, &cmd->dirty_root);
if (r < 0)
goto bad;
}
dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
r = dm_bitset_empty(&cmd->discard_info, &cmd->discard_root);
if (r < 0)
goto bad;
cmd->discard_block_size = 0;
cmd->discard_nr_blocks = 0;
r = __write_initial_superblock(cmd);
if (r)
goto bad;
cmd->clean_when_opened = true;
return 0;
bad:
dm_tm_destroy(cmd->tm);
dm_sm_destroy(cmd->metadata_sm);
return r;
}
static int __check_incompat_features(struct cache_disk_superblock *disk_super,
struct dm_cache_metadata *cmd)
{
uint32_t incompat_flags, features;
incompat_flags = le32_to_cpu(disk_super->incompat_flags);
features = incompat_flags & ~DM_CACHE_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 (bdev_read_only(cmd->bdev))
return 0;
features = le32_to_cpu(disk_super->compat_ro_flags) & ~DM_CACHE_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_cache_metadata *cmd)
{
int r;
struct dm_block *sblock;
struct cache_disk_superblock *disk_super;
unsigned long sb_flags;
r = superblock_read_lock(cmd, &sblock);
if (r < 0) {
DMERR("couldn't read lock 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) != cmd->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)cmd->data_block_size);
r = -EINVAL;
goto bad;
}
r = __check_incompat_features(disk_super, cmd);
if (r < 0)
goto bad;
r = dm_tm_open_with_sm(cmd->bm, CACHE_SUPERBLOCK_LOCATION,
disk_super->metadata_space_map_root,
sizeof(disk_super->metadata_space_map_root),
&cmd->tm, &cmd->metadata_sm);
if (r < 0) {
DMERR("tm_open_with_sm failed");
goto bad;
}
__setup_mapping_info(cmd);
dm_disk_bitset_init(cmd->tm, &cmd->dirty_info);
dm_disk_bitset_init(cmd->tm, &cmd->discard_info);
sb_flags = le32_to_cpu(disk_super->flags);
cmd->clean_when_opened = test_bit(CLEAN_SHUTDOWN, &sb_flags);
dm_bm_unlock(sblock);
return 0;
bad:
dm_bm_unlock(sblock);
return r;
}
static int __open_or_format_metadata(struct dm_cache_metadata *cmd,
bool format_device)
{
int r;
bool unformatted = false;
r = __superblock_all_zeroes(cmd->bm, &unformatted);
if (r)
return r;
if (unformatted)
return format_device ? __format_metadata(cmd) : -EPERM;
return __open_metadata(cmd);
}
static int __create_persistent_data_objects(struct dm_cache_metadata *cmd,
bool may_format_device)
{
int r;
cmd->bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
CACHE_MAX_CONCURRENT_LOCKS);
if (IS_ERR(cmd->bm)) {
DMERR("could not create block manager");
r = PTR_ERR(cmd->bm);
cmd->bm = NULL;
return r;
}
r = __open_or_format_metadata(cmd, may_format_device);
if (r) {
dm_block_manager_destroy(cmd->bm);
cmd->bm = NULL;
}
return r;
}
static void __destroy_persistent_data_objects(struct dm_cache_metadata *cmd)
{
dm_sm_destroy(cmd->metadata_sm);
dm_tm_destroy(cmd->tm);
dm_block_manager_destroy(cmd->bm);
}
typedef unsigned long (*flags_mutator)(unsigned long);
static void update_flags(struct cache_disk_superblock *disk_super,
flags_mutator mutator)
{
uint32_t sb_flags = mutator(le32_to_cpu(disk_super->flags));
disk_super->flags = cpu_to_le32(sb_flags);
}
static unsigned long set_clean_shutdown(unsigned long flags)
{
set_bit(CLEAN_SHUTDOWN, &flags);
return flags;
}
static unsigned long clear_clean_shutdown(unsigned long flags)
{
clear_bit(CLEAN_SHUTDOWN, &flags);
return flags;
}
static void read_superblock_fields(struct dm_cache_metadata *cmd,
struct cache_disk_superblock *disk_super)
{
cmd->version = le32_to_cpu(disk_super->version);
cmd->flags = le32_to_cpu(disk_super->flags);
cmd->root = le64_to_cpu(disk_super->mapping_root);
cmd->hint_root = le64_to_cpu(disk_super->hint_root);
cmd->discard_root = le64_to_cpu(disk_super->discard_root);
cmd->discard_block_size = le64_to_cpu(disk_super->discard_block_size);
cmd->discard_nr_blocks = to_dblock(le64_to_cpu(disk_super->discard_nr_blocks));
cmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
cmd->cache_blocks = to_cblock(le32_to_cpu(disk_super->cache_blocks));
strncpy(cmd->policy_name, disk_super->policy_name, sizeof(cmd->policy_name));
cmd->policy_version[0] = le32_to_cpu(disk_super->policy_version[0]);
cmd->policy_version[1] = le32_to_cpu(disk_super->policy_version[1]);
cmd->policy_version[2] = le32_to_cpu(disk_super->policy_version[2]);
cmd->policy_hint_size = le32_to_cpu(disk_super->policy_hint_size);
cmd->stats.read_hits = le32_to_cpu(disk_super->read_hits);
cmd->stats.read_misses = le32_to_cpu(disk_super->read_misses);
cmd->stats.write_hits = le32_to_cpu(disk_super->write_hits);
cmd->stats.write_misses = le32_to_cpu(disk_super->write_misses);
if (separate_dirty_bits(cmd))
cmd->dirty_root = le64_to_cpu(disk_super->dirty_root);
cmd->changed = false;
}
/*
* The mutator updates the superblock flags.
*/
static int __begin_transaction_flags(struct dm_cache_metadata *cmd,
flags_mutator mutator)
{
int r;
struct cache_disk_superblock *disk_super;
struct dm_block *sblock;
r = superblock_lock(cmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
update_flags(disk_super, mutator);
read_superblock_fields(cmd, disk_super);
dm_bm_unlock(sblock);
return dm_bm_flush(cmd->bm);
}
static int __begin_transaction(struct dm_cache_metadata *cmd)
{
int r;
struct cache_disk_superblock *disk_super;
struct dm_block *sblock;
/*
* We re-read the superblock every time. Shouldn't need to do this
* really.
*/
r = superblock_read_lock(cmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
read_superblock_fields(cmd, disk_super);
dm_bm_unlock(sblock);
return 0;
}
static int __commit_transaction(struct dm_cache_metadata *cmd,
flags_mutator mutator)
{
int r;
struct cache_disk_superblock *disk_super;
struct dm_block *sblock;
/*
* We need to know if the cache_disk_superblock exceeds a 512-byte sector.
*/
BUILD_BUG_ON(sizeof(struct cache_disk_superblock) > 512);
if (separate_dirty_bits(cmd)) {
r = dm_bitset_flush(&cmd->dirty_info, cmd->dirty_root,
&cmd->dirty_root);
if (r)
return r;
}
r = dm_bitset_flush(&cmd->discard_info, cmd->discard_root,
&cmd->discard_root);
if (r)
return r;
r = dm_tm_pre_commit(cmd->tm);
if (r < 0)
return r;
r = __save_sm_root(cmd);
if (r)
return r;
r = superblock_lock(cmd, &sblock);
if (r)
return r;
disk_super = dm_block_data(sblock);
disk_super->flags = cpu_to_le32(cmd->flags);
if (mutator)
update_flags(disk_super, mutator);
disk_super->mapping_root = cpu_to_le64(cmd->root);
if (separate_dirty_bits(cmd))
disk_super->dirty_root = cpu_to_le64(cmd->dirty_root);
disk_super->hint_root = cpu_to_le64(cmd->hint_root);
disk_super->discard_root = cpu_to_le64(cmd->discard_root);
disk_super->discard_block_size = cpu_to_le64(cmd->discard_block_size);
disk_super->discard_nr_blocks = cpu_to_le64(from_dblock(cmd->discard_nr_blocks));
disk_super->cache_blocks = cpu_to_le32(from_cblock(cmd->cache_blocks));
strncpy(disk_super->policy_name, cmd->policy_name, sizeof(disk_super->policy_name));
disk_super->policy_version[0] = cpu_to_le32(cmd->policy_version[0]);
disk_super->policy_version[1] = cpu_to_le32(cmd->policy_version[1]);
disk_super->policy_version[2] = cpu_to_le32(cmd->policy_version[2]);
disk_super->policy_hint_size = cpu_to_le32(cmd->policy_hint_size);
disk_super->read_hits = cpu_to_le32(cmd->stats.read_hits);
disk_super->read_misses = cpu_to_le32(cmd->stats.read_misses);
disk_super->write_hits = cpu_to_le32(cmd->stats.write_hits);
disk_super->write_misses = cpu_to_le32(cmd->stats.write_misses);
__copy_sm_root(cmd, disk_super);
return dm_tm_commit(cmd->tm, sblock);
}
/*----------------------------------------------------------------*/
/*
* The mappings are held in a dm-array that has 64-bit values stored in
* little-endian format. The index is the cblock, the high 48bits of the
* value are the oblock and the low 16 bit the flags.
*/
#define FLAGS_MASK ((1 << 16) - 1)
static __le64 pack_value(dm_oblock_t block, unsigned flags)
{
uint64_t value = from_oblock(block);
value <<= 16;
value = value | (flags & FLAGS_MASK);
return cpu_to_le64(value);
}
static void unpack_value(__le64 value_le, dm_oblock_t *block, unsigned *flags)
{
uint64_t value = le64_to_cpu(value_le);
uint64_t b = value >> 16;
*block = to_oblock(b);
*flags = value & FLAGS_MASK;
}
/*----------------------------------------------------------------*/
static struct dm_cache_metadata *metadata_open(struct block_device *bdev,
sector_t data_block_size,
bool may_format_device,
size_t policy_hint_size,
unsigned metadata_version)
{
int r;
struct dm_cache_metadata *cmd;
cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
if (!cmd) {
DMERR("could not allocate metadata struct");
return ERR_PTR(-ENOMEM);
}
cmd->version = metadata_version;
refcount_set(&cmd->ref_count, 1);
init_rwsem(&cmd->root_lock);
cmd->bdev = bdev;
cmd->data_block_size = data_block_size;
cmd->cache_blocks = 0;
cmd->policy_hint_size = policy_hint_size;
cmd->changed = true;
cmd->fail_io = false;
r = __create_persistent_data_objects(cmd, may_format_device);
if (r) {
kfree(cmd);
return ERR_PTR(r);
}
r = __begin_transaction_flags(cmd, clear_clean_shutdown);
if (r < 0) {
dm_cache_metadata_close(cmd);
return ERR_PTR(r);
}
return cmd;
}
/*
* We keep a little list of ref counted metadata objects to prevent two
* different target instances creating separate bufio instances. This is
* an issue if a table is reloaded before the suspend.
*/
static DEFINE_MUTEX(table_lock);
static LIST_HEAD(table);
static struct dm_cache_metadata *lookup(struct block_device *bdev)
{
struct dm_cache_metadata *cmd;
list_for_each_entry(cmd, &table, list)
if (cmd->bdev == bdev) {
refcount_inc(&cmd->ref_count);
return cmd;
}
return NULL;
}
static struct dm_cache_metadata *lookup_or_open(struct block_device *bdev,
sector_t data_block_size,
bool may_format_device,
size_t policy_hint_size,
unsigned metadata_version)
{
struct dm_cache_metadata *cmd, *cmd2;
mutex_lock(&table_lock);
cmd = lookup(bdev);
mutex_unlock(&table_lock);
if (cmd)
return cmd;
cmd = metadata_open(bdev, data_block_size, may_format_device,
policy_hint_size, metadata_version);
if (!IS_ERR(cmd)) {
mutex_lock(&table_lock);
cmd2 = lookup(bdev);
if (cmd2) {
mutex_unlock(&table_lock);
__destroy_persistent_data_objects(cmd);
kfree(cmd);
return cmd2;
}
list_add(&cmd->list, &table);
mutex_unlock(&table_lock);
}
return cmd;
}
static bool same_params(struct dm_cache_metadata *cmd, sector_t data_block_size)
{
if (cmd->data_block_size != data_block_size) {
DMERR("data_block_size (%llu) different from that in metadata (%llu)",
(unsigned long long) data_block_size,
(unsigned long long) cmd->data_block_size);
return false;
}
return true;
}
struct dm_cache_metadata *dm_cache_metadata_open(struct block_device *bdev,
sector_t data_block_size,
bool may_format_device,
size_t policy_hint_size,
unsigned metadata_version)
{
struct dm_cache_metadata *cmd = lookup_or_open(bdev, data_block_size, may_format_device,
policy_hint_size, metadata_version);
if (!IS_ERR(cmd) && !same_params(cmd, data_block_size)) {
dm_cache_metadata_close(cmd);
return ERR_PTR(-EINVAL);
}
return cmd;
}
void dm_cache_metadata_close(struct dm_cache_metadata *cmd)
{
if (refcount_dec_and_test(&cmd->ref_count)) {
mutex_lock(&table_lock);
list_del(&cmd->list);
mutex_unlock(&table_lock);
if (!cmd->fail_io)
__destroy_persistent_data_objects(cmd);
kfree(cmd);
}
}
/*
* Checks that the given cache block is either unmapped or clean.
*/
static int block_clean_combined_dirty(struct dm_cache_metadata *cmd, dm_cblock_t b,
bool *result)
{
int r;
__le64 value;
dm_oblock_t ob;
unsigned flags;
r = dm_array_get_value(&cmd->info, cmd->root, from_cblock(b), &value);
if (r)
return r;
unpack_value(value, &ob, &flags);
*result = !((flags & M_VALID) && (flags & M_DIRTY));
return 0;
}
static int blocks_are_clean_combined_dirty(struct dm_cache_metadata *cmd,
dm_cblock_t begin, dm_cblock_t end,
bool *result)
{
int r;
*result = true;
while (begin != end) {
r = block_clean_combined_dirty(cmd, begin, result);
if (r) {
DMERR("block_clean_combined_dirty failed");
return r;
}
if (!*result) {
DMERR("cache block %llu is dirty",
(unsigned long long) from_cblock(begin));
return 0;
}
begin = to_cblock(from_cblock(begin) + 1);
}
return 0;
}
static int blocks_are_clean_separate_dirty(struct dm_cache_metadata *cmd,
dm_cblock_t begin, dm_cblock_t end,
bool *result)
{
int r;
bool dirty_flag;
*result = true;
if (from_cblock(cmd->cache_blocks) == 0)
/* Nothing to do */
return 0;
r = dm_bitset_cursor_begin(&cmd->dirty_info, cmd->dirty_root,
from_cblock(cmd->cache_blocks), &cmd->dirty_cursor);
if (r) {
DMERR("%s: dm_bitset_cursor_begin for dirty failed", __func__);
return r;
}
r = dm_bitset_cursor_skip(&cmd->dirty_cursor, from_cblock(begin));
if (r) {
DMERR("%s: dm_bitset_cursor_skip for dirty failed", __func__);
dm_bitset_cursor_end(&cmd->dirty_cursor);
return r;
}
while (begin != end) {
/*
* We assume that unmapped blocks have their dirty bit
* cleared.
*/
dirty_flag = dm_bitset_cursor_get_value(&cmd->dirty_cursor);
if (dirty_flag) {
DMERR("%s: cache block %llu is dirty", __func__,
(unsigned long long) from_cblock(begin));
dm_bitset_cursor_end(&cmd->dirty_cursor);
*result = false;
return 0;
}
begin = to_cblock(from_cblock(begin) + 1);
if (begin == end)
break;
r = dm_bitset_cursor_next(&cmd->dirty_cursor);
if (r) {
DMERR("%s: dm_bitset_cursor_next for dirty failed", __func__);
dm_bitset_cursor_end(&cmd->dirty_cursor);
return r;
}
}
dm_bitset_cursor_end(&cmd->dirty_cursor);
return 0;
}
static int blocks_are_unmapped_or_clean(struct dm_cache_metadata *cmd,
dm_cblock_t begin, dm_cblock_t end,
bool *result)
{
if (separate_dirty_bits(cmd))
return blocks_are_clean_separate_dirty(cmd, begin, end, result);
else
return blocks_are_clean_combined_dirty(cmd, begin, end, result);
}
static bool cmd_write_lock(struct dm_cache_metadata *cmd)
{
down_write(&cmd->root_lock);
if (cmd->fail_io || dm_bm_is_read_only(cmd->bm)) {
up_write(&cmd->root_lock);