/* 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 */
/* Whether or not owning mapped_device is suspended */
int suspended;
- mempool_t *pending_pool;
-
atomic_t pending_exceptions_count;
+ mempool_t *pending_pool;
+
struct dm_exception_table pending;
struct dm_exception_table complete;
*/
spinlock_t pe_lock;
+ /* Chunks with outstanding reads */
+ spinlock_t tracked_chunk_lock;
+ mempool_t *tracked_chunk_pool;
+ struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
+
/* The on disk metadata handler */
struct dm_exception_store *store;
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];
-
/* Wait for events based on state_bits */
unsigned long state_bits;
int num_merging_chunks;
/*
+ * 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;
+
+ /*
* Incoming bios that overlap with chunks being merged must wait
* for them to be committed.
*/
static void snapshot_merge_next_chunks(struct dm_snapshot *s)
{
- int r;
+ int i, linear_chunks;
chunk_t old_chunk, new_chunk;
struct dm_io_region src, dest;
+ sector_t io_size;
uint64_t previous_count;
BUG_ON(!test_bit(RUNNING_MERGE, &s->state_bits));
goto shut;
}
- r = s->store->type->prepare_merge(s->store, &old_chunk, &new_chunk);
- if (r <= 0) {
- if (r < 0)
+ linear_chunks = s->store->type->prepare_merge(s->store, &old_chunk,
+ &new_chunk);
+ 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;
}
- /* TODO: use larger I/O size once we verify that kcopyd handles it */
+ /* Adjust old_chunk and new_chunk to reflect start of linear region */
+ old_chunk = old_chunk + 1 - linear_chunks;
+ new_chunk = new_chunk + 1 - linear_chunks;
+
+ /*
+ * Use one (potentially large) I/O to copy all 'linear_chunks'
+ * from the exception store to the origin
+ */
+ io_size = linear_chunks * s->store->chunk_size;
dest.bdev = s->origin->bdev;
dest.sector = chunk_to_sector(s->store, old_chunk);
- dest.count = min((sector_t)s->store->chunk_size,
- get_dev_size(dest.bdev) - dest.sector);
+ dest.count = min(io_size, get_dev_size(dest.bdev) - dest.sector);
src.bdev = s->cow->bdev;
src.sector = chunk_to_sector(s->store, new_chunk);
* significant impact on performance.
*/
previous_count = read_pending_exceptions_done_count();
- while (origin_write_extent(s, dest.sector, s->store->chunk_size)) {
+ while (origin_write_extent(s, dest.sector, io_size)) {
wait_event(_pending_exceptions_done,
(read_pending_exceptions_done_count() !=
previous_count));
down_write(&s->lock);
s->first_merging_chunk = old_chunk;
- s->num_merging_chunks = 1;
+ s->num_merging_chunks = linear_chunks;
up_write(&s->lock);
- __check_for_conflicting_io(s, old_chunk);
+ /* Wait until writes to all 'linear_chunks' drain */
+ for (i = 0; i < linear_chunks; i++)
+ __check_for_conflicting_io(s, old_chunk + i);
dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, merge_callback, s);
return;
shut:
down_write(&s->lock);
+ s->merge_failed = 1;
b = __release_queued_bios_after_merge(s);
up_write(&s->lock);
error_bios(b);
argv++;
argc--;
- r = dm_get_device(ti, cow_path, 0, 0,
- FMODE_READ | FMODE_WRITE, &s->cow);
+ r = dm_get_device(ti, cow_path, FMODE_READ | FMODE_WRITE, &s->cow);
if (r) {
ti->error = "Cannot get COW device";
goto bad_cow;
argv += args_used;
argc -= args_used;
- r = dm_get_device(ti, origin_path, 0, ti->len, origin_mode, &s->origin);
+ r = dm_get_device(ti, origin_path, origin_mode, &s->origin);
if (r) {
ti->error = "Cannot get origin device";
goto bad_origin;
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);
down_write(&s->lock);
- /* Full snapshots are not usable */
- if (!s->valid) {
- r = -EIO;
- goto out_unlock;
- }
+ /* Full merging snapshots are redirected to the origin */
+ if (!s->valid)
+ goto redirect_to_origin;
/* If the block is already remapped - use that */
e = dm_lookup_exception(&s->complete, chunk);
goto out_unlock;
}
+redirect_to_origin:
bio->bi_bdev = s->origin->bdev;
if (bio_rw(bio) == WRITE) {
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,
return -EINVAL;
}
- r = dm_get_device(ti, argv[0], 0, ti->len,
- dm_table_get_mode(ti->table), &dev);
+ r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &dev);
if (r) {
ti->error = "Cannot get target device";
return r;
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff