Let deadline_next_request() only consider the first zoned write per
zone. This patch fixes a race condition between deadline_next_request()
and completion of zoned writes.
Cc: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
block/mq-deadline.c | 24 +++++++++++++++++++++---
include/linux/blk-mq.h | 5 +++++
2 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 8c2bc9fdcf8c..d49e20d3011d 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -389,12 +389,30 @@ deadline_next_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
*/
spin_lock_irqsave(&dd->zone_lock, flags);
while (rq) {
+ unsigned int zno = blk_rq_zone_no(rq);
+
if (blk_req_can_dispatch_to_zone(rq))
break;
- if (blk_queue_nonrot(q))
- rq = deadline_latter_request(rq);
- else
+
+ WARN_ON_ONCE(!blk_queue_is_zoned(q));
+
+ if (!blk_queue_nonrot(q)) {
rq = deadline_skip_seq_writes(dd, rq);
+ if (!rq)
+ break;
+ rq = deadline_earlier_request(rq);
+ if (WARN_ON_ONCE(!rq))
+ break;
+ }
+
+ /*
+ * Skip all other write requests for the zone with zone number
+ * 'zno'. This prevents that this function selects a zoned write
+ * that is not the first write for a given zone.
+ */
+ while ((rq = deadline_latter_request(rq)) &&
+ blk_rq_zone_no(rq) == zno)
+ ;
}
spin_unlock_irqrestore(&dd->zone_lock, flags);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index e62feb17af96..515dfd04d736 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -1193,6 +1193,11 @@ static inline bool blk_req_can_dispatch_to_zone(struct request *rq)
return !blk_req_zone_is_write_locked(rq);
}
#else /* CONFIG_BLK_DEV_ZONED */
+static inline unsigned int blk_rq_zone_no(struct request *rq)
+{
+ return 0;
+}
+
static inline bool blk_req_needs_zone_write_lock(struct request *rq)
{
return false;
