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| author | NeilBrown <neilb@suse.com> | 2017-06-05 08:49:39 +0200 |
|---|---|---|
| committer | Shaohua Li <shli@fb.com> | 2017-06-13 19:18:01 +0200 |
| commit | cc27b0c78c79680d128dbac79de0d40556d041bb (patch) | |
| tree | 1f32d4acd29d825eecc1aef90d423cdacea8121c /drivers/md/raid10.c | |
| parent | Merge tag 'xtensa-20170612' of git://github.com/jcmvbkbc/linux-xtensa (diff) | |
| download | linux-cc27b0c78c79680d128dbac79de0d40556d041bb.tar.xz linux-cc27b0c78c79680d128dbac79de0d40556d041bb.zip | |
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/raid10.c')
| -rw-r--r-- | drivers/md/raid10.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 797ed60abd5e..52acffa7a06a 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1303,8 +1303,6 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio, sector_t sectors; int max_sectors; - md_write_start(mddev, bio); - /* * Register the new request and wait if the reconstruction * thread has put up a bar for new requests. @@ -1525,7 +1523,7 @@ static void __make_request(struct mddev *mddev, struct bio *bio, int sectors) raid10_write_request(mddev, bio, r10_bio); } -static void raid10_make_request(struct mddev *mddev, struct bio *bio) +static bool raid10_make_request(struct mddev *mddev, struct bio *bio) { struct r10conf *conf = mddev->private; sector_t chunk_mask = (conf->geo.chunk_mask & conf->prev.chunk_mask); @@ -1534,9 +1532,12 @@ static void raid10_make_request(struct mddev *mddev, struct bio *bio) if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } + if (!md_write_start(mddev, bio)) + return false; + /* * If this request crosses a chunk boundary, we need to split * it. @@ -1553,6 +1554,7 @@ static void raid10_make_request(struct mddev *mddev, struct bio *bio) /* In case raid10d snuck in to freeze_array */ wake_up(&conf->wait_barrier); + return true; } static void raid10_status(struct seq_file *seq, struct mddev *mddev) |