From cc27b0c78c79680d128dbac79de0d40556d041bb Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 5 Jun 2017 16:49:39 +1000 Subject: md: fix deadlock between mddev_suspend() and md_write_start() If mddev_suspend() races with md_write_start() we can deadlock with mddev_suspend() waiting for the request that is currently in md_write_start() to complete the ->make_request() call, and md_write_start() waiting for the metadata to be updated to mark the array as 'dirty'. As metadata updates done by md_check_recovery() only happen then the mddev_lock() can be claimed, and as mddev_suspend() is often called with the lock held, these threads wait indefinitely for each other. We fix this by having md_write_start() abort if mddev_suspend() is happening, and ->make_request() aborts if md_write_start() aborted. md_make_request() can detect this abort, decrease the ->active_io count, and wait for mddev_suspend(). Reported-by: Nix Fix: 68866e425be2(MD: no sync IO while suspended) Cc: stable@vger.kernel.org Signed-off-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/raid0.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'drivers/md/raid0.c') diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c index d6c0bc76e837..94d9ae9b0fd0 100644 --- a/drivers/md/raid0.c +++ b/drivers/md/raid0.c @@ -548,7 +548,7 @@ static void raid0_handle_discard(struct mddev *mddev, struct bio *bio) bio_endio(bio); } -static void raid0_make_request(struct mddev *mddev, struct bio *bio) +static bool raid0_make_request(struct mddev *mddev, struct bio *bio) { struct strip_zone *zone; struct md_rdev *tmp_dev; @@ -559,12 +559,12 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio) if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } if (unlikely((bio_op(bio) == REQ_OP_DISCARD))) { raid0_handle_discard(mddev, bio); - return; + return true; } bio_sector = bio->bi_iter.bi_sector; @@ -599,6 +599,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio) mddev_check_writesame(mddev, bio); mddev_check_write_zeroes(mddev, bio); generic_make_request(bio); + return true; } static void raid0_status(struct seq_file *seq, struct mddev *mddev) -- cgit