From: Damien Le Moal <damien.lemoal@xxxxxxx>
In case of a failed write request (all retries failed) and when using
libata, the SCSI error handler calls scsi_finish_command(). In the
case of blk-mq this means that scsi_mq_done() does not get called,
that blk_mq_complete_request() does not get called and also that the
mq-deadline .completed_request() method is not called. This results in
the target zone of the failed write request being left in a locked
state, preventing that any new write requests are issued to the same
zone.
Fix this by replacing the .completed_request() method with the
.finish_request() method as this method is always called whether or
not a request completes successfully. Since the .finish_request()
method is only called by the blk-mq core if a .prepare_request()
method exists, add a dummy .prepare_request() method.
Fixes: 5700f69178e9 ("mq-deadline: Introduce zone locking support")
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
[ bvanassche: edited patch description ]
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/mq-deadline.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index c56f211c8440..8ec0ba9f5386 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -535,13 +535,22 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
spin_unlock(&dd->lock);
}
+/*
+ * Nothing to do here. This is defined only to ensure that .finish_request
+ * method is called upon request completion.
+ */
+static void dd_prepare_request(struct request *rq, struct bio *bio)
+{
+}
+
/*
* For zoned block devices, write unlock the target zone of
* completed write requests. Do this while holding the zone lock
* spinlock so that the zone is never unlocked while deadline_fifo_request()
- * while deadline_next_request() are executing.
+ * or deadline_next_request() are executing. This function is called for
+ * all requests, whether or not these requests complete successfully.
*/
-static void dd_completed_request(struct request *rq)
+static void dd_finish_request(struct request *rq)
{
struct request_queue *q = rq->q;
@@ -756,7 +765,8 @@ static struct elevator_type mq_deadline = {
.ops.mq = {
.insert_requests = dd_insert_requests,
.dispatch_request = dd_dispatch_request,
- .completed_request = dd_completed_request,
+ .prepare_request = dd_prepare_request,
+ .finish_request = dd_finish_request,
.next_request = elv_rb_latter_request,
.former_request = elv_rb_former_request,
.bio_merge = dd_bio_merge,
--
2.16.2
