| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.13 095/110] md: fix a race condition for flush request handling | Date | Tue, 3 Oct 2017 14:29:57 +0200 |
| |
4.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Shaohua Li <shli@fb.com>
commit 79bf31a3b2a7ca467cfec8ff97d359a77065d01f upstream.
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 <nate.dailey@stratus.com> Tested-by: Nate Dailey <nate.dailey@stratus.com> Fix: cc27b0c78c79(md: fix deadlock between mddev_suspend() and md_write_start()) Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/md/md.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
--- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -439,16 +439,22 @@ static void md_submit_flush_data(struct 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)
|