blk-mq: Fix blk_mq_tagset_busy_iter() for shared tags

mainline inclusion
from mainline-v5.16-rc1
commit 0994c64e
category: bugfix
bugzilla: 186917, https://gitee.com/openeuler/kernel/issues/I5N1S5
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0994c64eb4159ba019e7fedc7ba0dd6a69235b40

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

Since it is now possible for a tagset to share a single set of tags, the
iter function should not re-iter the tags for the count of #hw queues in
that case. Rather it should just iter once.

Fixes: e155b0c2 ("blk-mq: Use shared tags for shared sbitmap support")
Reported-by: NKashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Tested-by: NKashyap Desai <kashyap.desai@broadcom.com>
Link: https://lore.kernel.org/r/1634550083-202815-1-git-send-email-john.garry@huawei.comSigned-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NZhang Wensheng <zhangwensheng5@huawei.com>
Reviewed-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

block/blk-mq-tag.c

@@ -454,9 +454,12 @@ void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn,
 void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
 		busy_tag_iter_fn *fn, void *priv)
 {
-	int i;
+	unsigned int flags = tagset->flags;
+	int i, nr_tags;
 
-	for (i = 0; i < tagset->nr_hw_queues; i++) {
+	nr_tags = blk_mq_is_sbitmap_shared(flags) ? 1 : tagset->nr_hw_queues;
+
+	for (i = 0; i < nr_tags; i++) {
 		if (tagset->tags && tagset->tags[i])
 			__blk_mq_all_tag_iter(tagset->tags[i], fn, priv,
 					      BT_TAG_ITER_STARTED);