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>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
block/mq-deadline.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 3122c471f473..32a2cc013ed3 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -302,6 +302,7 @@ static bool deadline_is_seq_write(struct deadline_data *dd, struct request *rq)
return blk_rq_pos(prev) + blk_rq_sectors(prev) == blk_rq_pos(rq);
}
+#ifdef CONFIG_BLK_DEV_ZONED
/*
* Skip all write requests that are sequential from @rq, even if we cross
* a zone boundary.
@@ -318,6 +319,7 @@ static struct request *deadline_skip_seq_writes(struct deadline_data *dd,
return rq;
}
+#endif
/*
* For the specified data direction, return the next request to
@@ -386,9 +388,25 @@ 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 __maybe_unused;
+
if (blk_req_can_dispatch_to_zone(rq))
break;
+
+#ifdef CONFIG_BLK_DEV_ZONED
+ zno = blk_rq_zone_no(rq);
+
rq = deadline_skip_seq_writes(dd, rq);
+
+ /*
+ * 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 && blk_rq_zone_no(rq) == zno &&
+ blk_rq_is_seq_zoned_write(rq))
+ rq = deadline_latter_request(rq);
+#endif
}
spin_unlock_irqrestore(&dd->zone_lock, flags);
