When there is one merging snapshot and other non-merging snapshots, make exceptions in non-merging snapshots while merging. This is not yet complete (the exception is not made when remapping directly to the origin), another patch fixes that. Signed-off-by: Mikulas Patocka Reviewed-by: Mike Snitzer --- drivers/md/dm-snap.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) Index: linux-2.6.31-fast-new-2/drivers/md/dm-snap.c =================================================================== --- linux-2.6.31-fast-new-2.orig/drivers/md/dm-snap.c 2009-10-16 21:48:39.000000000 +0200 +++ linux-2.6.31-fast-new-2/drivers/md/dm-snap.c 2009-10-16 21:48:42.000000000 +0200 @@ -275,6 +275,8 @@ struct origin { static struct list_head *_origins; static struct rw_semaphore _origins_lock; +static DECLARE_WAIT_QUEUE_HEAD(_pending_exception_done); + static int init_origin_hash(void) { int i; @@ -671,6 +673,9 @@ static int init_hash_tables(struct dm_sn static void flush_bios(struct bio *bio); static void error_bios(struct bio *bio); +static int __origin_write(struct list_head *snapshots, + sector_t sector, struct bio *bio); + static void merge_callback(int read_err, unsigned long write_err, void *context); @@ -678,6 +683,9 @@ static void snapshot_merge_process(struc { int r; chunk_t old_chunk, new_chunk; + struct origin *o; + chunk_t min_chunksize; + int must_wait; struct dm_io_region src, dest; BUG_ON(!s->merge_running); @@ -708,6 +716,27 @@ static void snapshot_merge_process(struc src.sector = chunk_to_sector(s->store, new_chunk); src.count = dest.count; +test_again: + /* Reallocate other snapshots */ + down_read(&_origins_lock); + o = __lookup_origin(s->origin->bdev); + must_wait = 0; + min_chunksize = __minimum_chunk_size(o); + if (min_chunksize) { + chunk_t n; + for (n = 0; n < s->store->chunk_size; n += min_chunksize) { + r = __origin_write(&o->snapshots, dest.sector + n, + NULL); + if (r == DM_MAPIO_SUBMITTED) + must_wait = 1; + } + } + up_read(&_origins_lock); + if (must_wait) { + sleep_on_timeout(&_pending_exception_done, HZ / 100 + 1); + goto test_again; + } + down_write(&s->lock); s->merge_write_interlock = old_chunk; s->merge_write_interlock_n = 1; @@ -1247,6 +1276,8 @@ static void pending_complete(struct dm_s origin_bios = bio_list_get(&pe->origin_bios); free_pending_exception(pe); + wake_up_all(&_pending_exception_done); + up_write(&s->lock); /* Submit any pending write bios */