block: fix memleak of bio integrity data

7c20f116 ("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 7c20f116.

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

Fixes: 7c20f116 ("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>

block/bio-integrity.c

@@ -87,7 +87,7 @@ EXPORT_SYMBOL(bio_integrity_alloc);
  * Description: Used to free the integrity portion of a bio. Usually
  * called from bio_free().
  */
-static void bio_integrity_free(struct bio *bio)
+void bio_integrity_free(struct bio *bio)
 {
 	struct bio_integrity_payload *bip = bio_integrity(bio);
 	struct bio_set *bs = bio->bi_pool;

block/bio.c

@@ -233,6 +233,9 @@ struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
 void bio_uninit(struct bio *bio)
 {
 	bio_disassociate_blkg(bio);
+
+	if (bio_integrity(bio))
+		bio_integrity_free(bio);
 }
 EXPORT_SYMBOL(bio_uninit);
 

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);