On 5/30/24 00:16, Nitesh Shetty wrote:
+static inline bool blk_copy_offload_attempt_combine(struct request_queue *q,
+ struct bio *bio)
+{
+ struct blk_plug *plug = current->plug;
+ struct request *rq;
+
+ if (!plug || rq_list_empty(plug->mq_list))
+ return false;
+
+ rq_list_for_each(&plug->mq_list, rq) {
+ if (rq->q == q) {
+ if (!blk_copy_offload_combine(rq, bio))
+ return true;
+ break;
+ }
+
+ /*
+ * Only keep iterating plug list for combines if we have multiple
+ * queues
+ */
+ if (!plug->multiple_queues)
+ break;
+ }
+ return false;
+}
This new approach has the following two disadvantages:
* Without plug, REQ_OP_COPY_SRC and REQ_OP_COPY_DST are not combined. These two
operation types are the only operation types for which not using a plug causes
an I/O failure.
* A loop is required to combine the REQ_OP_COPY_SRC and REQ_OP_COPY_DST operations.
Please switch to the approach Hannes suggested, namely bio chaining. Chaining
REQ_OP_COPY_SRC and REQ_OP_COPY_DST bios before these are submitted eliminates the
two disadvantages mentioned above.
Thanks,
Bart.
