block: fix bugs in bio-integrity mempool usage

Fix two bugs in the bio integrity code:

 use_bip_pool() always returns 0 because it checks against the wrong limit,
 causing the mempool to be used only when regular allocation fails.

 When the mempool is used as a fallback we don't free the data properly.

Signed-Off-By: Chuck Ebbert <cebbert@redhat.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

fs/bio-integrity.c

@@ -61,7 +61,7 @@ static inline unsigned int vecs_to_idx(unsigned int nr)
 
 static inline int use_bip_pool(unsigned int idx)
 {
-	if (idx == BIOVEC_NR_POOLS)
+	if (idx == BIOVEC_MAX_IDX)
 		return 1;
 
 	return 0;
@@ -95,6 +95,7 @@ struct bio_integrity_payload *bio_integrity_alloc_bioset(struct bio *bio,
 
 	/* Use mempool if lower order alloc failed or max vecs were requested */
 	if (bip == NULL) {
+		idx = BIOVEC_MAX_IDX;  /* so we free the payload properly later */
 		bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
 
 		if (unlikely(bip == NULL)) {