@@ -1186,18 +1186,51 @@ static void blk_mq_handle_zone_resource(struct request *rq,
__blk_mq_requeue_request(rq);
}
+enum prep_dispatch {
+ PREP_DISPATCH_OK,
+ PREP_DISPATCH_NO_TAG,
+ PREP_DISPATCH_NO_BUDGET,
+};
+
+static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
+ bool ask_budget)
+{
+ struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
+
+ if (ask_budget && !blk_mq_get_dispatch_budget(rq->q)) {
+ blk_mq_put_driver_tag(rq);
+ return PREP_DISPATCH_NO_BUDGET;
+ }
+
+ if (!blk_mq_get_driver_tag(rq)) {
+ /*
+ * The initial allocation attempt failed, so we need to
+ * rerun the hardware queue when a tag is freed. The
+ * waitqueue takes care of that. If the queue is run
+ * before we add this entry back on the dispatch list,
+ * we'll re-run it below.
+ */
+ if (!blk_mq_mark_tag_wait(hctx, rq)) {
+ /* budget is always obtained before getting tag */
+ blk_mq_put_dispatch_budget(rq->q);
+ return PREP_DISPATCH_NO_TAG;
+ }
+ }
+
+ return PREP_DISPATCH_OK;
+}
+
/*
* Returns true if we did some work AND can potentially do more.
*/
bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
bool got_budget)
{
+ enum prep_dispatch prep;
struct request_queue *q = hctx->queue;
struct request *rq;
- bool no_tag = false;
int errors, queued;
blk_status_t ret = BLK_STS_OK;
- bool no_budget_avail = false;
LIST_HEAD(zone_list);
if (list_empty(list))
@@ -1215,31 +1248,9 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
rq = list_first_entry(list, struct request, queuelist);
WARN_ON_ONCE(hctx != rq->mq_hctx);
- if (!got_budget && !blk_mq_get_dispatch_budget(q)) {
- blk_mq_put_driver_tag(rq);
- no_budget_avail = true;
+ prep = blk_mq_prep_dispatch_rq(rq, !got_budget);
+ if (prep != PREP_DISPATCH_OK)
break;
- }
-
- if (!blk_mq_get_driver_tag(rq)) {
- /*
- * The initial allocation attempt failed, so we need to
- * rerun the hardware queue when a tag is freed. The
- * waitqueue takes care of that. If the queue is run
- * before we add this entry back on the dispatch list,
- * we'll re-run it below.
- */
- if (!blk_mq_mark_tag_wait(hctx, rq)) {
- blk_mq_put_dispatch_budget(q);
- /*
- * For non-shared tags, the RESTART check
- * will suffice.
- */
- if (hctx->flags & BLK_MQ_F_TAG_SHARED)
- no_tag = true;
- break;
- }
- }
list_del_init(&rq->queuelist);
@@ -1282,6 +1293,18 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
*/
if (!list_empty(list)) {
bool needs_restart;
+ bool no_tag = false;
+ bool no_budget_avail = false;
+
+ /*
+ * For non-shared tags, the RESTART check
+ * will suffice.
+ */
+ if (prep == PREP_DISPATCH_NO_TAG &&
+ (hctx->flags & BLK_MQ_F_TAG_SHARED))
+ no_tag = true;
+ if (prep == PREP_DISPATCH_NO_BUDGET)
+ no_budget_avail = true;
/*
* If we didn't flush the entire list, we could have told
Move code for getting driver tag and bugget into one helper, so blk_mq_dispatch_rq_list gets a bit simpified, and easier to read. Meantime move updating of 'no_tag' and 'no_budget_avaiable' into the branch for handling partial dispatch because that is exactly consumer of the two local variables. Also rename the parameter of 'got_budget' as 'ask_budget'. No functional change. Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/blk-mq.c | 75 +++++++++++++++++++++++++++++++++----------------- 1 file changed, 49 insertions(+), 26 deletions(-)