5.4-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei ming.lei@redhat.com
[ Upstream commit 85067747cf9888249fa11fa49ef75af5192d3988 ]
Given request-based DM now uses blk-mq's blk_mq_queue_inflight() to determine if outstanding IO has completed (and DM has no control over the blk-mq state machine used to track outstanding IO) it is unsafe to wakeup waiter (dm_wait_for_completion) before blk-mq has cleared a request's state bits (e.g. MQ_RQ_IN_FLIGHT or MQ_RQ_COMPLETE). As such dm_wait_for_completion() could be left to wait indefinitely if no other requests complete.
Fix this by eliminating request-based DM's use of waitqueue to wait for blk-mq requests to complete in dm_wait_for_completion.
Signed-off-by: Ming Lei ming.lei@redhat.com Depends-on: 3c94d83cb3526 ("blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()") Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer snitzer@redhat.com Stable-dep-of: 1e1fd567d32f ("dm suspend: return -ERESTARTSYS instead of -EINTR") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-rq.c | 4 --- drivers/md/dm.c | 64 ++++++++++++++++++++++++++++------------------ 2 files changed, 39 insertions(+), 29 deletions(-)
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c index 6bc61927d3205..3d6ac63ee85ae 100644 --- a/drivers/md/dm-rq.c +++ b/drivers/md/dm-rq.c @@ -143,10 +143,6 @@ static void rq_end_stats(struct mapped_device *md, struct request *orig) */ static void rq_completed(struct mapped_device *md) { - /* nudge anyone waiting on suspend queue */ - if (unlikely(wq_has_sleeper(&md->wait))) - wake_up(&md->wait); - /* * dm_put() must be at the end of this function. See the comment above */ diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 36d21a5d09ebf..f6f5b68a6950b 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -637,28 +637,6 @@ static void free_tio(struct dm_target_io *tio) bio_put(&tio->clone); }
-static bool md_in_flight_bios(struct mapped_device *md) -{ - int cpu; - struct hd_struct *part = &dm_disk(md)->part0; - long sum = 0; - - for_each_possible_cpu(cpu) { - sum += part_stat_local_read_cpu(part, in_flight[0], cpu); - sum += part_stat_local_read_cpu(part, in_flight[1], cpu); - } - - return sum != 0; -} - -static bool md_in_flight(struct mapped_device *md) -{ - if (queue_is_mq(md->queue)) - return blk_mq_queue_inflight(md->queue); - else - return md_in_flight_bios(md); -} - u64 dm_start_time_ns_from_clone(struct bio *bio) { struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone); @@ -2428,15 +2406,29 @@ void dm_put(struct mapped_device *md) } EXPORT_SYMBOL_GPL(dm_put);
-static int dm_wait_for_completion(struct mapped_device *md, long task_state) +static bool md_in_flight_bios(struct mapped_device *md) +{ + int cpu; + struct hd_struct *part = &dm_disk(md)->part0; + long sum = 0; + + for_each_possible_cpu(cpu) { + sum += part_stat_local_read_cpu(part, in_flight[0], cpu); + sum += part_stat_local_read_cpu(part, in_flight[1], cpu); + } + + return sum != 0; +} + +static int dm_wait_for_bios_completion(struct mapped_device *md, long task_state) { int r = 0; DEFINE_WAIT(wait);
- while (1) { + while (true) { prepare_to_wait(&md->wait, &wait, task_state);
- if (!md_in_flight(md)) + if (!md_in_flight_bios(md)) break;
if (signal_pending_state(task_state, current)) { @@ -2453,6 +2445,28 @@ static int dm_wait_for_completion(struct mapped_device *md, long task_state) return r; }
+static int dm_wait_for_completion(struct mapped_device *md, long task_state) +{ + int r = 0; + + if (!queue_is_mq(md->queue)) + return dm_wait_for_bios_completion(md, task_state); + + while (true) { + if (!blk_mq_queue_inflight(md->queue)) + break; + + if (signal_pending_state(task_state, current)) { + r = -EINTR; + break; + } + + msleep(5); + } + + return r; +} + /* * Process the deferred bios */