block: Introduce integrity data ownership flag

A filesystem might supply its own integrity metadata.  Introduce a
flag that indicates whether the filesystem or the block layer owns the
integrity buffer.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

---

diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c
@@ -107,7 +107,8 @@ void bio_integrity_free(struct bio *bio,
 	BUG_ON(bip == NULL);
 
 	/* A cloned bio doesn't own the integrity metadata */
-	if (!bio_flagged(bio, BIO_CLONED) && bip->bip_buf != NULL)
+	if (!bio_flagged(bio, BIO_CLONED) && !bio_flagged(bio, BIO_FS_INTEGRITY)
+	    && bip->bip_buf != NULL)
 		kfree(bip->bip_buf);
 
 	mempool_free(bip->bip_vec, bs->bvec_pools[bip->bip_pool]);
diff --git a/include/linux/bio.h b/include/linux/bio.h
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -131,6 +131,7 @@ struct bio {
 #define BIO_BOUNCED	5	/* bio is a bounce bio */
 #define BIO_USER_MAPPED 6	/* contains user pages */
 #define BIO_EOPNOTSUPP	7	/* not supported */
+#define BIO_FS_INTEGRITY 8	/* fs owns integrity data, not block layer */
 #define bio_flagged(bio, flag)	((bio)->bi_flags & (1 << (flag)))
 
 /*