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dm snapshot: report merge failure in status 

Set 'merge_failed' flag if a snapshot fails to merge.  Update
snapshot_status() to report "Merge failed" if 'merge_failed' is set.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mike Snitzer 2009-12-10 23:52:35 +00:00 committed by Alasdair G Kergon
parent 8a2d528620
commit d8ddb1cfff
1 changed files with 28 additions and 2 deletions
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30
drivers/md/dm-snap.c
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@ -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,