[dm-devel] [PATCH] dm-cache: discard block size causes data corruption
heinzm at redhat.com
heinzm at redhat.com
Wed Mar 26 15:27:24 UTC 2014
From: Heinz Mauelshagen <heinzm at redhat.com>
Discard block size not being equal to cache block size causes data
corruption by erroneously avoiding migrations in issue_copy() because
the discard state is being cleared for a group of cache blocks when it
should not.
Drop that distinction altogether and make both sizes equal.
Signed-off-by: Heinz Mauelshagen <heinzm at redhat.com>
---
drivers/md/dm-cache-block-types.h | 11 ----
drivers/md/dm-cache-metadata.c | 34 ++++++-------
drivers/md/dm-cache-metadata.h | 6 +--
drivers/md/dm-cache-target.c | 103 ++++++++++----------------------------
4 files changed, 46 insertions(+), 108 deletions(-)
diff --git a/drivers/md/dm-cache-block-types.h b/drivers/md/dm-cache-block-types.h
index bed4ad4..aac0e2d 100644
--- a/drivers/md/dm-cache-block-types.h
+++ b/drivers/md/dm-cache-block-types.h
@@ -19,7 +19,6 @@
typedef dm_block_t __bitwise__ dm_oblock_t;
typedef uint32_t __bitwise__ dm_cblock_t;
-typedef dm_block_t __bitwise__ dm_dblock_t;
static inline dm_oblock_t to_oblock(dm_block_t b)
{
@@ -41,14 +40,4 @@ static inline uint32_t from_cblock(dm_cblock_t b)
return (__force uint32_t) b;
}
-static inline dm_dblock_t to_dblock(dm_block_t b)
-{
- return (__force dm_dblock_t) b;
-}
-
-static inline dm_block_t from_dblock(dm_dblock_t b)
-{
- return (__force dm_block_t) b;
-}
-
#endif /* DM_CACHE_BLOCK_TYPES_H */
diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 9ef0752..cbd568a 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -109,7 +109,7 @@ struct dm_cache_metadata {
dm_block_t discard_root;
sector_t discard_block_size;
- dm_dblock_t discard_nr_blocks;
+ dm_oblock_t discard_nr_blocks;
sector_t data_block_size;
dm_cblock_t cache_blocks;
@@ -302,7 +302,7 @@ static int __write_initial_superblock(struct dm_cache_metadata *cmd)
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->discard_nr_blocks = cpu_to_le64(from_oblock(cmd->discard_nr_blocks));
disk_super->metadata_block_size = cpu_to_le32(DM_CACHE_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
disk_super->data_block_size = cpu_to_le32(cmd->data_block_size);
disk_super->cache_blocks = cpu_to_le32(0);
@@ -496,7 +496,7 @@ static void read_superblock_fields(struct dm_cache_metadata *cmd,
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->discard_nr_blocks = to_oblock(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));
@@ -594,7 +594,7 @@ static int __commit_transaction(struct dm_cache_metadata *cmd,
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->discard_nr_blocks = cpu_to_le64(from_oblock(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]);
@@ -771,15 +771,15 @@ out:
int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
sector_t discard_block_size,
- dm_dblock_t new_nr_entries)
+ dm_oblock_t new_nr_entries)
{
int r;
down_write(&cmd->root_lock);
r = dm_bitset_resize(&cmd->discard_info,
cmd->discard_root,
- from_dblock(cmd->discard_nr_blocks),
- from_dblock(new_nr_entries),
+ from_oblock(cmd->discard_nr_blocks),
+ from_oblock(new_nr_entries),
false, &cmd->discard_root);
if (!r) {
cmd->discard_block_size = discard_block_size;
@@ -792,28 +792,28 @@ int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
return r;
}
-static int __set_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
+static int __set_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
{
return dm_bitset_set_bit(&cmd->discard_info, cmd->discard_root,
- from_dblock(b), &cmd->discard_root);
+ from_oblock(b), &cmd->discard_root);
}
-static int __clear_discard(struct dm_cache_metadata *cmd, dm_dblock_t b)
+static int __clear_discard(struct dm_cache_metadata *cmd, dm_oblock_t b)
{
return dm_bitset_clear_bit(&cmd->discard_info, cmd->discard_root,
- from_dblock(b), &cmd->discard_root);
+ from_oblock(b), &cmd->discard_root);
}
-static int __is_discarded(struct dm_cache_metadata *cmd, dm_dblock_t b,
+static int __is_discarded(struct dm_cache_metadata *cmd, dm_oblock_t b,
bool *is_discarded)
{
return dm_bitset_test_bit(&cmd->discard_info, cmd->discard_root,
- from_dblock(b), &cmd->discard_root,
+ from_oblock(b), &cmd->discard_root,
is_discarded);
}
static int __discard(struct dm_cache_metadata *cmd,
- dm_dblock_t dblock, bool discard)
+ dm_oblock_t dblock, bool discard)
{
int r;
@@ -826,7 +826,7 @@ static int __discard(struct dm_cache_metadata *cmd,
}
int dm_cache_set_discard(struct dm_cache_metadata *cmd,
- dm_dblock_t dblock, bool discard)
+ dm_oblock_t dblock, bool discard)
{
int r;
@@ -844,8 +844,8 @@ static int __load_discards(struct dm_cache_metadata *cmd,
dm_block_t b;
bool discard;
- for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
- dm_dblock_t dblock = to_dblock(b);
+ for (b = 0; b < from_oblock(cmd->discard_nr_blocks); b++) {
+ dm_oblock_t dblock = to_oblock(b);
if (cmd->clean_when_opened) {
r = __is_discarded(cmd, dblock, &discard);
diff --git a/drivers/md/dm-cache-metadata.h b/drivers/md/dm-cache-metadata.h
index cd906f1..ce8468b 100644
--- a/drivers/md/dm-cache-metadata.h
+++ b/drivers/md/dm-cache-metadata.h
@@ -72,14 +72,14 @@ dm_cblock_t dm_cache_size(struct dm_cache_metadata *cmd);
int dm_cache_discard_bitset_resize(struct dm_cache_metadata *cmd,
sector_t discard_block_size,
- dm_dblock_t new_nr_entries);
+ dm_oblock_t new_nr_entries);
typedef int (*load_discard_fn)(void *context, sector_t discard_block_size,
- dm_dblock_t dblock, bool discarded);
+ dm_oblock_t dblock, bool discarded);
int dm_cache_load_discards(struct dm_cache_metadata *cmd,
load_discard_fn fn, void *context);
-int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_dblock_t dblock, bool discard);
+int dm_cache_set_discard(struct dm_cache_metadata *cmd, dm_oblock_t dblock, bool discard);
int dm_cache_remove_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock);
int dm_cache_insert_mapping(struct dm_cache_metadata *cmd, dm_cblock_t cblock, dm_oblock_t oblock);
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 074b9c8..6d39457 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -237,9 +237,8 @@ struct cache {
/*
* origin_blocks entries, discarded if set.
*/
- dm_dblock_t discard_nr_blocks;
+ dm_oblock_t discard_nr_blocks;
unsigned long *discard_bitset;
- uint32_t discard_block_size; /* a power of 2 times sectors per block */
/*
* Rather than reconstructing the table line for the status we just
@@ -526,48 +525,33 @@ static dm_block_t block_div(dm_block_t b, uint32_t n)
return b;
}
-static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
-{
- uint32_t discard_blocks = cache->discard_block_size;
- dm_block_t b = from_oblock(oblock);
-
- if (!block_size_is_power_of_two(cache))
- discard_blocks = discard_blocks / cache->sectors_per_block;
- else
- discard_blocks >>= cache->sectors_per_block_shift;
-
- b = block_div(b, discard_blocks);
-
- return to_dblock(b);
-}
-
-static void set_discard(struct cache *cache, dm_dblock_t b)
+static void set_discard(struct cache *cache, dm_oblock_t b)
{
unsigned long flags;
atomic_inc(&cache->stats.discard_count);
spin_lock_irqsave(&cache->lock, flags);
- set_bit(from_dblock(b), cache->discard_bitset);
+ set_bit(from_oblock(b), cache->discard_bitset);
spin_unlock_irqrestore(&cache->lock, flags);
}
-static void clear_discard(struct cache *cache, dm_dblock_t b)
+static void clear_discard(struct cache *cache, dm_oblock_t b)
{
unsigned long flags;
spin_lock_irqsave(&cache->lock, flags);
- clear_bit(from_dblock(b), cache->discard_bitset);
+ clear_bit(from_oblock(b), cache->discard_bitset);
spin_unlock_irqrestore(&cache->lock, flags);
}
-static bool is_discarded(struct cache *cache, dm_dblock_t b)
+static bool is_discarded(struct cache *cache, dm_oblock_t b)
{
int r;
unsigned long flags;
spin_lock_irqsave(&cache->lock, flags);
- r = test_bit(from_dblock(b), cache->discard_bitset);
+ r = test_bit(from_oblock(b), cache->discard_bitset);
spin_unlock_irqrestore(&cache->lock, flags);
return r;
@@ -579,8 +563,7 @@ static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
unsigned long flags;
spin_lock_irqsave(&cache->lock, flags);
- r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
- cache->discard_bitset);
+ r = test_bit(from_oblock(b), cache->discard_bitset);
spin_unlock_irqrestore(&cache->lock, flags);
return r;
@@ -705,7 +688,7 @@ static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
check_if_tick_bio_needed(cache, bio);
remap_to_origin(cache, bio);
if (bio_data_dir(bio) == WRITE)
- clear_discard(cache, oblock_to_dblock(cache, oblock));
+ clear_discard(cache, oblock);
}
static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
@@ -715,7 +698,7 @@ static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
remap_to_cache(cache, bio, cblock);
if (bio_data_dir(bio) == WRITE) {
set_dirty(cache, oblock, cblock);
- clear_discard(cache, oblock_to_dblock(cache, oblock));
+ clear_discard(cache, oblock);
}
}
@@ -1288,14 +1271,14 @@ static void process_flush_bio(struct cache *cache, struct bio *bio)
static void process_discard_bio(struct cache *cache, struct bio *bio)
{
dm_block_t start_block = dm_sector_div_up(bio->bi_iter.bi_sector,
- cache->discard_block_size);
+ cache->sectors_per_block);
dm_block_t end_block = bio_end_sector(bio);
dm_block_t b;
- end_block = block_div(end_block, cache->discard_block_size);
+ end_block = block_div(end_block, cache->sectors_per_block);
for (b = start_block; b < end_block; b++)
- set_discard(cache, to_dblock(b));
+ set_discard(cache, to_oblock(b));
bio_endio(bio, 0);
}
@@ -2171,35 +2154,6 @@ static int create_cache_policy(struct cache *cache, struct cache_args *ca,
return 0;
}
-/*
- * We want the discard block size to be a power of two, at least the size
- * of the cache block size, and have no more than 2^14 discard blocks
- * across the origin.
- */
-#define MAX_DISCARD_BLOCKS (1 << 14)
-
-static bool too_many_discard_blocks(sector_t discard_block_size,
- sector_t origin_size)
-{
- (void) sector_div(origin_size, discard_block_size);
-
- return origin_size > MAX_DISCARD_BLOCKS;
-}
-
-static sector_t calculate_discard_block_size(sector_t cache_block_size,
- sector_t origin_size)
-{
- sector_t discard_block_size;
-
- discard_block_size = roundup_pow_of_two(cache_block_size);
-
- if (origin_size)
- while (too_many_discard_blocks(discard_block_size, origin_size))
- discard_block_size *= 2;
-
- return discard_block_size;
-}
-
#define DEFAULT_MIGRATION_THRESHOLD 2048
static int cache_create(struct cache_args *ca, struct cache **result)
@@ -2321,16 +2275,13 @@ static int cache_create(struct cache_args *ca, struct cache **result)
}
clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
- cache->discard_block_size =
- calculate_discard_block_size(cache->sectors_per_block,
- cache->origin_sectors);
- cache->discard_nr_blocks = oblock_to_dblock(cache, cache->origin_blocks);
- cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
+ cache->discard_nr_blocks = cache->origin_blocks;
+ cache->discard_bitset = alloc_bitset(from_oblock(cache->discard_nr_blocks));
if (!cache->discard_bitset) {
*error = "could not allocate discard bitset";
goto bad;
}
- clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
+ clear_bitset(cache->discard_bitset, from_oblock(cache->discard_nr_blocks));
cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
if (IS_ERR(cache->copier)) {
@@ -2614,16 +2565,16 @@ static int write_discard_bitset(struct cache *cache)
{
unsigned i, r;
- r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
- cache->discard_nr_blocks);
+ r = dm_cache_discard_bitset_resize(cache->cmd, cache->sectors_per_block,
+ cache->origin_blocks);
if (r) {
DMERR("could not resize on-disk discard bitset");
return r;
}
- for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
- r = dm_cache_set_discard(cache->cmd, to_dblock(i),
- is_discarded(cache, to_dblock(i)));
+ for (i = 0; i < from_oblock(cache->discard_nr_blocks); i++) {
+ r = dm_cache_set_discard(cache->cmd, to_oblock(i),
+ is_discarded(cache, to_oblock(i)));
if (r)
return r;
}
@@ -2720,16 +2671,14 @@ static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
}
static int load_discard(void *context, sector_t discard_block_size,
- dm_dblock_t dblock, bool discard)
+ dm_oblock_t oblock, bool discard)
{
struct cache *cache = context;
- /* FIXME: handle mis-matched block size */
-
if (discard)
- set_discard(cache, dblock);
+ set_discard(cache, oblock);
else
- clear_discard(cache, dblock);
+ clear_discard(cache, oblock);
return 0;
}
@@ -3120,8 +3069,8 @@ static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
/*
* FIXME: these limits may be incompatible with the cache device
*/
- limits->max_discard_sectors = cache->discard_block_size * 1024;
- limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
+ limits->max_discard_sectors = cache->sectors_per_block * 1024;
+ limits->discard_granularity = cache->sectors_per_block << SECTOR_SHIFT;
}
static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
--
1.8.5.3
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