block: fix memleak of bio integrity data

7c20f11680a4 ("bio-integrity: stop abusing bi_end_io") moves
bio_integrity_free from bio_uninit() to bio_integrity_verify_fn()
and bio_endio(). This way looks wrong because bio may be freed
without calling bio_endio(), for example, blk_rq_unprep_clone() is
called from dm_mq_queue_rq() when the underlying queue of dm-mpath
is busy.

So memory leak of bio integrity data is caused by commit 7c20f11680a4.

Fixes this issue by re-adding bio_integrity_free() to bio_uninit().

Fixes: 7c20f11680a4 ("bio-integrity: stop abusing bi_end_io")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by Justin Tee <justin.tee@broadcom.com>

Add commit log, and simplify/fix the original patch wroten by Justin.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk.h b/block/blk.h
index 2bea401..6842f28 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -121,6 +121,7 @@ static inline void blk_rq_bio_prep(struct request *rq, struct bio *bio,
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 void blk_flush_integrity(void);
 bool __bio_integrity_endio(struct bio *);
+void bio_integrity_free(struct bio *bio);
 static inline bool bio_integrity_endio(struct bio *bio)
 {
 	if (bio_integrity(bio))
@@ -166,6 +167,9 @@ static inline bool bio_integrity_endio(struct bio *bio)
 {
 	return true;
 }
+static inline void bio_integrity_free(struct bio *bio)
+{
+}
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 
 unsigned long blk_rq_timeout(unsigned long timeout);