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