blk-integrity: empty implementation when disabled

This patch moves the blk_integrity_payload definition outside the
CONFIG_BLK_DEV_INTERITY dependency and provides empty function
implementations when the kernel configuration disables integrity
extensions. This simplifies drivers that make use of these to map user
data so they don't need to repeat the same configuration checks.
Signed-off-by: Keith Busch <keith.busch@intel.com>

Updated by Jens to pass an error pointer return from
bio_integrity_alloc(), otherwise if CONFIG_BLK_DEV_INTEGRITY isn't
set, we return a weird ENOMEM from __nvme_submit_user_cmd()
if a meta buffer is set.
Signed-off-by: Jens Axboe <axboe@fb.com>

block/bio-integrity.c

@@ -66,7 +66,7 @@ struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
 	}
 
 	if (unlikely(!bip))
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	memset(bip, 0, sizeof(*bip));
 
@@ -89,7 +89,7 @@ struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
 	return bip;
 err:
 	mempool_free(bip, bs->bio_integrity_pool);
-	return NULL;
+	return ERR_PTR(-ENOMEM);
 }
 EXPORT_SYMBOL(bio_integrity_alloc);
 

drivers/nvme/host/core.c

@@ -190,8 +190,8 @@ int __nvme_submit_user_cmd(struct request_queue *q, struct nvme_command *cmd,
 			}
 
 			bip = bio_integrity_alloc(bio, GFP_KERNEL, 1);
-			if (!bip) {
-				ret = -ENOMEM;
+			if (IS_ERR(bip)) {
+				ret = PTR_ERR(bip);
 				goto out_free_meta;
 			}
 

drivers/target/target_core_iblock.c

@@ -613,9 +613,9 @@ iblock_alloc_bip(struct se_cmd *cmd, struct bio *bio)
 	}
 
 	bip = bio_integrity_alloc(bio, GFP_NOIO, cmd->t_prot_nents);
-	if (!bip) {
+	if (IS_ERR(bip)) {
 		pr_err("Unable to allocate bio_integrity_payload\n");
-		return -ENOMEM;
+		return PTR_ERR(bip);
 	}
 
 	bip->bip_iter.bi_size = (cmd->data_length / dev->dev_attrib.block_size) *

include/linux/bio.h

@@ -318,16 +318,6 @@ enum bip_flags {
 	BIP_IP_CHECKSUM		= 1 << 4, /* IP checksum */
 };
 
-#if defined(CONFIG_BLK_DEV_INTEGRITY)
-
-static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
-{
-	if (bio->bi_rw & REQ_INTEGRITY)
-		return bio->bi_integrity;
-
-	return NULL;
-}
-
 /*
  * bio integrity payload
  */
@@ -349,6 +339,16 @@ struct bio_integrity_payload {
 	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
 };
 
+#if defined(CONFIG_BLK_DEV_INTEGRITY)
+
+static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
+{
+	if (bio->bi_rw & REQ_INTEGRITY)
+		return bio->bi_integrity;
+
+	return NULL;
+}
+
 static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 {
 	struct bio_integrity_payload *bip = bio_integrity(bio);
@@ -795,6 +795,18 @@ static inline bool bio_integrity_flagged(struct bio *bio, enum bip_flags flag)
 	return false;
 }
 
+static inline void *bio_integrity_alloc(struct bio * bio, gfp_t gfp,
+								unsigned int nr)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
+					unsigned int len, unsigned int offset)
+{
+	return 0;
+}
+
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 
 #endif /* CONFIG_BLOCK */