Commit daec338b authored by Mike Snitzer's avatar Mike Snitzer
Browse files

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: default avatarMike Snitzer <snitzer@redhat.com>
Acked-by: default avatarJoe Thornber <ejt@redhat.com>
parent 8d30abff

drivers/md/dm-thin.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

		}

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