blk-mq: enforce op-specific segment limits in blk_insert_cloned_request
The block layer might merge together discard requests up until the
max_discard_segments limit is hit, but blk_insert_cloned_request checks
the segment count against max_segments regardless of the req op. This
can result in errors like the following when discards are issued through
a DM device and max_discard_segments exceeds max_segments for the queue
of the chosen underlying device.
blk_insert_cloned_request: over max segments limit. (256 > 129)
Fix this by looking at the req_op and enforcing the appropriate segment
limit - max_discard_segments for REQ_OP_DISCARDs and max_segments for
everything else.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230301000655.48112-1-ushankar@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk.h b/block/blk.h
index e835f21..cc4e887 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -156,6 +156,13 @@ static inline bool blk_discard_mergable(struct request *req)
return false;
}
+static inline unsigned int blk_rq_get_max_segments(struct request *rq)
+{
+ if (req_op(rq) == REQ_OP_DISCARD)
+ return queue_max_discard_segments(rq->q);
+ return queue_max_segments(rq->q);
+}
+
static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
enum req_op op)
{
