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| author |   NeilBrown <neilb@suse.com> | 2017-06-05 16:49:39 +1000 |
|---|---|---|
| committer |   Shaohua Li <shli@fb.com> | 2017-06-13 10:18:01 -0700 |
| commit | cc27b0c78c79680d128dbac79de0d40556d041bb (patch) | |
| tree | 1f32d4acd29d825eecc1aef90d423cdacea8121c /drivers/md/multipath.c | |
| parent | Merge tag 'xtensa-20170612' of git://github.com/jcmvbkbc/linux-xtensa (diff) | |
| download | linux-dev-cc27b0c78c79680d128dbac79de0d40556d041bb.tar.xz linux-dev-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/multipath.c')
| -rw-r--r-- | drivers/md/multipath.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c index e95d521d93e9..c8d985ba008d 100644 --- a/drivers/md/multipath.c +++ b/drivers/md/multipath.c @@ -106,7 +106,7 @@ static void multipath_end_request(struct bio *bio) rdev_dec_pending(rdev, conf->mddev); } -static void multipath_make_request(struct mddev *mddev, struct bio * bio) +static bool multipath_make_request(struct mddev *mddev, struct bio * bio) { struct mpconf *conf = mddev->private; struct multipath_bh * mp_bh; @@ -114,7 +114,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio) if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); - return; + return true; } mp_bh = mempool_alloc(conf->pool, GFP_NOIO); @@ -126,7 +126,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio) if (mp_bh->path < 0) { bio_io_error(bio); mempool_free(mp_bh, conf->pool); - return; + return true; } multipath = conf->multipaths + mp_bh->path; @@ -141,7 +141,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio) mddev_check_writesame(mddev, &mp_bh->bio); mddev_check_write_zeroes(mddev, &mp_bh->bio); generic_make_request(&mp_bh->bio); - return; + return true; } static void multipath_status(struct seq_file *seq, struct mddev *mddev) |