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authorNeilBrown <neilb@suse.com>2017-06-05 16:49:39 +1000
committerShaohua Li <shli@fb.com>2017-06-13 10:18:01 -0700
commitcc27b0c78c79680d128dbac79de0d40556d041bb (patch)
tree1f32d4acd29d825eecc1aef90d423cdacea8121c /drivers/md/raid0.c
parent63f700aab4c11d46626de3cd051dae56cf7e9056 (diff)
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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 <nix@esperi.org.uk> Fix: 68866e425be2(MD: no sync IO while suspended) Cc: stable@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/raid0.c')
-rw-r--r--drivers/md/raid0.c7
1 files changed, 4 insertions, 3 deletions
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)