From 79bf31a3b2a7ca467cfec8ff97d359a77065d01f Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Thu, 21 Sep 2017 09:55:28 -0700 Subject: [PATCH] md: fix a race condition for flush request handling md_submit_flush_data calls pers->make_request, which missed the suspend check. Fix it with the new md_handle_request API. Reported-by: Nate Dailey Tested-by: Nate Dailey Fix: cc27b0c78c79(md: fix deadlock between mddev_suspend() and md_write_start()) Cc: stable@vger.kernel.org Reviewed-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/md.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 1db1a22ed835..0ff1bbf6c90e 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -447,16 +447,22 @@ static void md_submit_flush_data(struct work_struct *ws) struct mddev *mddev = container_of(ws, struct mddev, flush_work); struct bio *bio = mddev->flush_bio; + /* + * must reset flush_bio before calling into md_handle_request to avoid a + * deadlock, because other bios passed md_handle_request suspend check + * could wait for this and below md_handle_request could wait for those + * bios because of suspend check + */ + mddev->flush_bio = NULL; + wake_up(&mddev->sb_wait); + if (bio->bi_iter.bi_size == 0) /* an empty barrier - all done */ bio_endio(bio); else { bio->bi_opf &= ~REQ_PREFLUSH; - mddev->pers->make_request(mddev, bio); + md_handle_request(mddev, bio); } - - mddev->flush_bio = NULL; - wake_up(&mddev->sb_wait); } void md_flush_request(struct mddev *mddev, struct bio *bio) -- 2.20.1