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>
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@ -989,14 +989,6 @@ static void wait_barrier(struct r1conf *conf, sector_t sector_nr)
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_wait_barrier(conf, idx);
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}
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static void wait_all_barriers(struct r1conf *conf)
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{
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int idx;
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for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++)
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_wait_barrier(conf, idx);
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}
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static void _allow_barrier(struct r1conf *conf, int idx)
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{
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atomic_dec(&conf->nr_pending[idx]);
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@ -1010,14 +1002,6 @@ static void allow_barrier(struct r1conf *conf, sector_t sector_nr)
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_allow_barrier(conf, idx);
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}
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static void allow_all_barriers(struct r1conf *conf)
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{
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int idx;
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for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++)
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_allow_barrier(conf, idx);
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}
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/* conf->resync_lock should be held */
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static int get_unqueued_pending(struct r1conf *conf)
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{
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@ -1645,8 +1629,12 @@ static void print_conf(struct r1conf *conf)
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static void close_sync(struct r1conf *conf)
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{
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wait_all_barriers(conf);
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allow_all_barriers(conf);
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int idx;
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for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) {
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_wait_barrier(conf, idx);
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_allow_barrier(conf, idx);
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}
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mempool_destroy(conf->r1buf_pool);
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conf->r1buf_pool = NULL;
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