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| author | Nate Dailey <nate.dailey@stratus.com> | 2017-10-17 14:17:03 +0200 |
|---|---|---|
| committer | Shaohua Li <shli@fb.com> | 2017-11-02 05:32:21 +0100 |
| commit | f6eca2d43ed694ab8124dd24c88277f7eca93b7d (patch) | |
| tree | 1ad48d4f54a13f586f9efcc7f1404d089300265c | |
| parent | md: use TASK_IDLE instead of blocking signals (diff) | |
| download | linux-f6eca2d43ed694ab8124dd24c88277f7eca93b7d.tar.xz linux-f6eca2d43ed694ab8124dd24c88277f7eca93b7d.zip | |
raid1: prevent freeze_array/wait_all_barriers deadlock
If freeze_array is attempted in the middle of close_sync/
wait_all_barriers, deadlock can occur.
freeze_array will wait for nr_pending and nr_queued to line up.
wait_all_barriers increments nr_pending for each barrier bucket, one
at a time, but doesn't actually issue IO that could be counted in
nr_queued. So freeze_array is blocked until wait_all_barriers
completes and allow_all_barriers runs. At the same time, when
_wait_barrier sees array_frozen == 1, it stops and waits for
freeze_array to complete.
Prevent the deadlock by making close_sync call _wait_barrier and
_allow_barrier for one bucket at a time, instead of deferring the
_allow_barrier calls until after all _wait_barriers are complete.
Signed-off-by: Nate Dailey <nate.dailey@stratus.com>
Fix: fd76863e37fe(RAID1: a new I/O barrier implementation to remove resync window)
Reviewed-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org (v4.11)
Signed-off-by: Shaohua Li <shli@fb.com>
| -rw-r--r-- | drivers/md/raid1.c | 24 |
1 files changed, 6 insertions, 18 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 1f36473c79dc..038f5eb299ce 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -989,14 +989,6 @@ static void wait_barrier(struct r1conf *conf, sector_t sector_nr) _wait_barrier(conf, idx); } -static void wait_all_barriers(struct r1conf *conf) -{ - int idx; - - for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) - _wait_barrier(conf, idx); -} - static void _allow_barrier(struct r1conf *conf, int idx) { atomic_dec(&conf->nr_pending[idx]); @@ -1010,14 +1002,6 @@ static void allow_barrier(struct r1conf *conf, sector_t sector_nr) _allow_barrier(conf, idx); } -static void allow_all_barriers(struct r1conf *conf) -{ - int idx; - - for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) - _allow_barrier(conf, idx); -} - /* conf->resync_lock should be held */ static int get_unqueued_pending(struct r1conf *conf) { @@ -1645,8 +1629,12 @@ static void print_conf(struct r1conf *conf) static void close_sync(struct r1conf *conf) { - wait_all_barriers(conf); - allow_all_barriers(conf); + int idx; + + for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) { + _wait_barrier(conf, idx); + _allow_barrier(conf, idx); + } mempool_destroy(conf->r1buf_pool); conf->r1buf_pool = NULL; |