diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2008-07-21 12:00:32 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2008-07-21 12:00:32 +0100 |
| commit | cd45daffd1f7b53aac0835b23e97f814ec3f10dc (patch) | |
| tree | 17d35682a8a97f3a73f513531f08ba7e0c8cd718 /drivers/md/dm-snap.h | |
| parent | def052d21c4e77975bb75cf212f018ec913f8e2f (diff) | |
dm snapshot: track snapshot reads
Whenever a snapshot read gets mapped through to the origin, track it in
a per-snapshot hash table indexed by chunk number, using memory allocated
from a new per-snapshot mempool.
We need to track these reads to avoid race conditions which will be fixed
by patches that follow.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-snap.h')
| -rw-r--r-- | drivers/md/dm-snap.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h index 24f9fb73b98..70dc961f40d 100644 --- a/drivers/md/dm-snap.h +++ b/drivers/md/dm-snap.h @@ -130,6 +130,10 @@ struct exception_store { void *context; }; +#define DM_TRACKED_CHUNK_HASH_SIZE 16 +#define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ + (DM_TRACKED_CHUNK_HASH_SIZE - 1)) + struct dm_snapshot { struct rw_semaphore lock; struct dm_target *ti; @@ -174,6 +178,11 @@ struct dm_snapshot { /* Queue of snapshot writes for ksnapd to flush */ struct bio_list queued_bios; struct work_struct queued_bios_work; + + /* Chunks with outstanding reads */ + mempool_t *tracked_chunk_pool; + spinlock_t tracked_chunk_lock; + struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; }; /* |