From daec338bbdaa96ba5b14c4777603e65ef74c769b Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 11 Dec 2013 14:01:20 -0500 Subject: [PATCH] dm thin: add mappings to end of prepared_* lists Mappings could be processed in descending logical block order, particularly if buffered IO is used. This could adversely affect the latency of IO processing. Fix this by adding mappings to the end of the 'prepared_mappings' and 'prepared_discards' lists. Signed-off-by: Mike Snitzer Acked-by: Joe Thornber --- drivers/md/dm-thin.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 1988019df5c9..efa3d42ac70a 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -535,7 +535,7 @@ static void __maybe_add_mapping(struct dm_thin_new_mapping *m) struct pool *pool = m->tc->pool; if (m->quiesced && m->prepared) { - list_add(&m->list, &pool->prepared_mappings); + list_add_tail(&m->list, &pool->prepared_mappings); wake_worker(pool); } } @@ -1058,7 +1058,7 @@ static void process_discard(struct thin_c *tc, struct bio *bio) if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) { spin_lock_irqsave(&pool->lock, flags); - list_add(&m->list, &pool->prepared_discards); + list_add_tail(&m->list, &pool->prepared_discards); spin_unlock_irqrestore(&pool->lock, flags); wake_worker(pool); } @@ -2919,7 +2919,7 @@ static int thin_endio(struct dm_target *ti, struct bio *bio, int err) if (!list_empty(&work)) { spin_lock_irqsave(&pool->lock, flags); list_for_each_entry_safe(m, tmp, &work, list) - list_add(&m->list, &pool->prepared_discards); + list_add_tail(&m->list, &pool->prepared_discards); spin_unlock_irqrestore(&pool->lock, flags); wake_worker(pool); } -- 2.20.1