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authorMing Lei <ming.lei@redhat.com>2020-06-30 18:24:58 +0800
committerJens Axboe <axboe@kernel.dk>2020-06-30 07:51:48 -0600
commit7538352453189abf3a96461e187b1085b0ae0c6c (patch)
treee22ebc96ca8706dfab2b25b453b308d86903a4c5 /block/blk-mq.c
parent445874e89f662c8c6a56e6bb820cbe9fbef61428 (diff)
downloadlinux-7538352453189abf3a96461e187b1085b0ae0c6c.tar.bz2
blk-mq: move getting driver tag and budget into one helper
Move code for getting driver tag and budget into one helper, so blk_mq_dispatch_rq_list gets a bit simplified, and easier to read. Meantime move updating of 'no_tag' and 'no_budget_available' 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. Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Baolin Wang <baolin.wang7@gmail.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Christoph Hellwig <hch@infradead.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Baolin Wang <baolin.wang7@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-mq.c')
-rw-r--r--block/blk-mq.c66
1 files changed, 40 insertions, 26 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 492aeda44da6..3e370f5bc40a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1255,18 +1255,50 @@ 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 need_budget)
+{
+ struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
+
+ if (need_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)) {
+ 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, *nxt;
- 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))
@@ -1284,31 +1316,9 @@ 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);
@@ -1361,6 +1371,10 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
*/
if (!list_empty(list)) {
bool needs_restart;
+ /* For non-shared tags, the RESTART check will suffice */
+ bool no_tag = prep == PREP_DISPATCH_NO_TAG &&
+ (hctx->flags & BLK_MQ_F_TAG_SHARED);
+ bool no_budget_avail = prep == PREP_DISPATCH_NO_BUDGET;
/*
* If we didn't flush the entire list, we could have told