From 80ae49aaed32af72630251eb06161b15cde15ac8 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 31 Jan 2014 14:30:37 -0500 Subject: [PATCH] dm cache: do not add migration to completed list before unhooking bio When completing an overwrite bio, in overwrite_endio(), the associated migration should not be added to the 'completed_migrations' until the bio's fields are restored with dm_unhook_bio(). Otherwise, do_worker() can race to process 'completed_migrations' before dm_unhook_bio() -- so the bio's bi_end_io is incorrect. This is unlikely to cause any problems given the current code but should be fixed on the basis of correctness. Also, the cache's spinlock only needs to be held when manipulating the 'completed_migrations' list -- other changes don't need protection. Signed-off-by: Mike Snitzer Acked-by: Joe Thornber --- drivers/md/dm-cache-target.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 14256b7..db09444 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -1010,13 +1010,15 @@ static void overwrite_endio(struct bio *bio, int err) struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size); unsigned long flags; + dm_unhook_bio(&pb->hook_info, bio); + if (err) mg->err = true; + mg->requeue_holder = false; + spin_lock_irqsave(&cache->lock, flags); list_add_tail(&mg->list, &cache->completed_migrations); - dm_unhook_bio(&pb->hook_info, bio); - mg->requeue_holder = false; spin_unlock_irqrestore(&cache->lock, flags); wake_worker(cache); -- 2.7.4