blk-mq-sched: Fix blk_mq_sched_alloc_tags() error handling

mainline inclusion
from mainline-v5.14-rc1
commit b93af305
category: bugfix
bugzilla: 177012 https://gitee.com/openeuler/kernel/issues/I4DDEL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b93af3055d6f32d3b0361cfdb110c9399c1241ba

---------------------------

If the blk_mq_sched_alloc_tags() -> blk_mq_alloc_rqs() call fails, then we
call blk_mq_sched_free_tags() -> blk_mq_free_rqs().

It is incorrect to do so, as any rqs would have already been freed in the
blk_mq_alloc_rqs() call.

Fix by calling blk_mq_free_rq_map() only directly.

Fixes: 6917ff0b ("blk-mq-sched: refactor scheduler initialization")
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/1627378373-148090-1-git-send-email-john.garry@huawei.comSigned-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NLaibin Qiu <qiulaibin@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

block/blk-mq-sched.c

@@ -505,19 +505,6 @@ void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
 	percpu_ref_put(&q->q_usage_counter);
 }
 
-static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
-				   struct blk_mq_hw_ctx *hctx,
-				   unsigned int hctx_idx)
-{
-	unsigned int flags = set->flags & ~BLK_MQ_F_TAG_HCTX_SHARED;
-
-	if (hctx->sched_tags) {
-		blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
-		blk_mq_free_rq_map(hctx->sched_tags, flags);
-		hctx->sched_tags = NULL;
-	}
-}
-
 static int blk_mq_sched_alloc_tags(struct request_queue *q,
 				   struct blk_mq_hw_ctx *hctx,
 				   unsigned int hctx_idx)
@@ -533,8 +520,10 @@ static int blk_mq_sched_alloc_tags(struct request_queue *q,
 		return -ENOMEM;
 
 	ret = blk_mq_alloc_rqs(set, hctx->sched_tags, hctx_idx, q->nr_requests);
-	if (ret)
-		blk_mq_sched_free_tags(set, hctx, hctx_idx);
+	if (ret) {
+		blk_mq_free_rq_map(hctx->sched_tags, set->flags);
+		hctx->sched_tags = NULL;
+	}
 
 	return ret;
 }