diff options
| -rw-r--r-- | drivers/md/dm-snap.c | 30 |
1 files changed, 28 insertions, 2 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index bb4b733697b..4c80e82f941 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -71,7 +71,10 @@ struct dm_snapshot { /* List of snapshots per Origin */ struct list_head list; - /* You can't use a snapshot if this is 0 (e.g. if full) */ + /* + * You can't use a snapshot if this is 0 (e.g. if full). + * A snapshot-merge target never clears this. + */ int valid; /* Origin writes don't trigger exceptions until this is set */ @@ -107,6 +110,21 @@ struct dm_snapshot { spinlock_t tracked_chunk_lock; struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; + /* + * The merge operation failed if this flag is set. + * Failure modes are handled as follows: + * - I/O error reading the header + * => don't load the target; abort. + * - Header does not have "valid" flag set + * => use the origin; forget about the snapshot. + * - I/O error when reading exceptions + * => don't load the target; abort. + * (We can't use the intermediate origin state.) + * - I/O error while merging + * => stop merging; set merge_failed; process I/O normally. + */ + int merge_failed; + /* Wait for events based on state_bits */ unsigned long state_bits; @@ -900,9 +918,13 @@ static void snapshot_merge_next_chunks(struct dm_snapshot *s) linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk, &new_chunk); if (linear_chunks <= 0) { - if (linear_chunks < 0) + if (linear_chunks < 0) { DMERR("Read error in exception store: " "shutting down merge"); + down_write(&s->lock); + s->merge_failed = 1; + up_write(&s->lock); + } goto shut; } @@ -988,6 +1010,7 @@ static void merge_callback(int read_err, unsigned long write_err, void *context) shut: down_write(&s->lock); + s->merge_failed = 1; b = __release_queued_bios_after_merge(s); up_write(&s->lock); error_bios(b); @@ -1090,6 +1113,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) INIT_LIST_HEAD(&s->list); spin_lock_init(&s->pe_lock); s->state_bits = 0; + s->merge_failed = 0; s->first_merging_chunk = 0; s->num_merging_chunks = 0; bio_list_init(&s->bios_queued_during_merge); @@ -1835,6 +1859,8 @@ static int snapshot_status(struct dm_target *ti, status_type_t type, if (!snap->valid) DMEMIT("Invalid"); + else if (snap->merge_failed) + DMEMIT("Merge failed"); else { if (snap->store->type->usage) { sector_t total_sectors, sectors_allocated, |