nbd has a defect that blk_mq_tag_to_rq() might return a freed
request in nbd_read_stat(). We need a new mechanism if we want to
fix this in nbd driver, which is rather complicated.
Thus use blk_mq_find_and_get_req() to replace blk_mq_tag_to_rq(),
which can make sure the returned request is not freed, and then we
can do more checking while 'cmd->lock' is hold.
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
block/blk-mq-tag.c | 5 +++--
block/blk-mq.c | 1 +
include/linux/blk-mq.h | 3 +++
3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 86f87346232a..b4f66b75b4d1 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -200,8 +200,8 @@ struct bt_iter_data {
bool reserved;
};
-static struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags,
- unsigned int bitnr)
+struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags,
+ unsigned int bitnr)
{
struct request *rq;
unsigned long flags;
@@ -213,6 +213,7 @@ static struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags,
spin_unlock_irqrestore(&tags->lock, flags);
return rq;
}
+EXPORT_SYMBOL(blk_mq_find_and_get_req);
static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
{
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 08626cb0534c..5113aa3788a2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -916,6 +916,7 @@ void blk_mq_put_rq_ref(struct request *rq)
else if (refcount_dec_and_test(&rq->ref))
__blk_mq_free_request(rq);
}
+EXPORT_SYMBOL(blk_mq_put_rq_ref);
static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
struct request *rq, void *priv, bool reserved)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 13ba1861e688..03e02990609d 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -637,4 +637,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio);
void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx,
struct lock_class_key *key);
+void blk_mq_put_rq_ref(struct request *rq);
+struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags,
+ unsigned int bitnr);
#endif
--
2.31.1
