diff options
| author | Nate Dailey <nate.dailey@stratus.com> | 2017-10-17 08:17:03 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-30 08:40:52 +0000 |
| commit | d92105f93aeb2c80f6840bed9af71d3f97321916 (patch) | |
| tree | ff37eaf33d92ff5b81331115b371c3568c793334 /drivers/md/raid1.c | |
| parent | 77a38e88ccbc9e6451333f742b18d0fe5176c5cd (diff) | |
raid1: prevent freeze_array/wait_all_barriers deadlock
commit f6eca2d43ed694ab8124dd24c88277f7eca93b7d upstream.
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>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md/raid1.c')
| -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 f3f3e40dc9d8..e4e8f9e565b7 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -990,14 +990,6 @@ 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]); @@ -1011,14 +1003,6 @@ 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) { @@ -1654,8 +1638,12 @@ 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; |