block: factor out a bio_integrity_action helper

Split the logic to see if a bio needs integrity metadata from
bio_integrity_prep into a reusable helper than can be called from
file system code.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Anuj Gupta <[e-mail]>
Reviewed-by: Kanchan Joshi <[e-mail]>
Reviewed-by: Martin K. Petersen <[e-mail]>
Reviewed-by: Darrick J. Wong <[e-mail]>
Tested-by: Anuj Gupta <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

block/bio-integrity-auto.c

···
 	return bip->bip_flags & BIP_CHECK_FLAGS;
 }
 
-static bool bi_offload_capable(struct blk_integrity *bi)
-{
-	return bi->metadata_size == bi->pi_tuple_size;
-}
-
 /**
  * __bio_integrity_endio - Integrity I/O completion function
  * @bio:	Protected bio
···
 /**
  * bio_integrity_prep - Prepare bio for integrity I/O
  * @bio:	bio to prepare
+ * @action:	preparation action needed (BI_ACT_*)
  *
- * Checks if the bio already has an integrity payload attached.  If it does, the
- * payload has been generated by another kernel subsystem, and we just pass it
- * through.
- * Otherwise allocates integrity payload and for writes the integrity metadata
- * will be generated.  For reads, the completion handler will verify the
- * metadata.
+ * Allocate the integrity payload.  For writes, generate the integrity metadata
+ * and for reads, setup the completion handler to verify the metadata.
+ *
+ * This is used for bios that do not have user integrity payloads attached.
  */
-bool bio_integrity_prep(struct bio *bio)
+void bio_integrity_prep(struct bio *bio, unsigned int action)
 {
 	struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
 	struct bio_integrity_data *bid;
-	bool set_flags = true;
-	gfp_t gfp = GFP_NOIO;
-
-	if (!bi)
-		return true;
-
-	if (!bio_sectors(bio))
-		return true;
-
-	/* Already protected? */
-	if (bio_integrity(bio))
-		return true;
-
-	switch (bio_op(bio)) {
-	case REQ_OP_READ:
-		if (bi->flags & BLK_INTEGRITY_NOVERIFY) {
-			if (bi_offload_capable(bi))
-				return true;
-			set_flags = false;
-		}
-		break;
-	case REQ_OP_WRITE:
-		/*
-		 * Zero the memory allocated to not leak uninitialized kernel
-		 * memory to disk for non-integrity metadata where nothing else
-		 * initializes the memory.
-		 */
-		if (bi->flags & BLK_INTEGRITY_NOGENERATE) {
-			if (bi_offload_capable(bi))
-				return true;
-			set_flags = false;
-			gfp |= __GFP_ZERO;
-		} else if (bi->metadata_size > bi->pi_tuple_size)
-			gfp |= __GFP_ZERO;
-		break;
-	default:
-		return true;
-	}
-
-	if (WARN_ON_ONCE(bio_has_crypt_ctx(bio)))
-		return true;
 
 	bid = mempool_alloc(&bid_pool, GFP_NOIO);
 	bio_integrity_init(bio, &bid->bip, &bid->bvec, 1);
 	bid->bio = bio;
 	bid->bip.bip_flags |= BIP_BLOCK_INTEGRITY;
-	bio_integrity_alloc_buf(bio, gfp & __GFP_ZERO);
+	bio_integrity_alloc_buf(bio, action & BI_ACT_ZERO);
 
 	bip_set_seed(&bid->bip, bio->bi_iter.bi_sector);
 
-	if (set_flags) {
+	if (action & BI_ACT_CHECK) {
 		if (bi->csum_type == BLK_INTEGRITY_CSUM_IP)
 			bid->bip.bip_flags |= BIP_IP_CHECKSUM;
 		if (bi->csum_type)
···
 		blk_integrity_generate(bio);
 	else
 		bid->saved_bio_iter = bio->bi_iter;
-	return true;
 }
 EXPORT_SYMBOL(bio_integrity_prep);
 

block/bio-integrity.c

···
  */
 
 #include <linux/blk-integrity.h>
+#include <linux/t10-pi.h>
 #include "blk.h"
 
 struct bio_integrity_alloc {
···
 };
 
 static mempool_t integrity_buf_pool;
+
+static bool bi_offload_capable(struct blk_integrity *bi)
+{
+	return bi->metadata_size == bi->pi_tuple_size;
+}
+
+unsigned int __bio_integrity_action(struct bio *bio)
+{
+	struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
+
+	if (WARN_ON_ONCE(bio_has_crypt_ctx(bio)))
+		return 0;
+
+	switch (bio_op(bio)) {
+	case REQ_OP_READ:
+		if (bi->flags & BLK_INTEGRITY_NOVERIFY) {
+			if (bi_offload_capable(bi))
+				return 0;
+			return BI_ACT_BUFFER;
+		}
+		return BI_ACT_BUFFER | BI_ACT_CHECK;
+	case REQ_OP_WRITE:
+		/*
+		 * Flush masquerading as write?
+		 */
+		if (!bio_sectors(bio))
+			return 0;
+
+		/*
+		 * Zero the memory allocated to not leak uninitialized kernel
+		 * memory to disk for non-integrity metadata where nothing else
+		 * initializes the memory.
+		 */
+		if (bi->flags & BLK_INTEGRITY_NOGENERATE) {
+			if (bi_offload_capable(bi))
+				return 0;
+			return BI_ACT_BUFFER | BI_ACT_ZERO;
+		}
+
+		if (bi->metadata_size > bi->pi_tuple_size)
+			return BI_ACT_BUFFER | BI_ACT_CHECK | BI_ACT_ZERO;
+		return BI_ACT_BUFFER | BI_ACT_CHECK;
+	default:
+		return 0;
+	}
+}
+EXPORT_SYMBOL_GPL(__bio_integrity_action);
 
 void bio_integrity_alloc_buf(struct bio *bio, bool zero_buffer)
 {

block/blk-mq.c

···
 	struct request_queue *q = bdev_get_queue(bio->bi_bdev);
 	struct blk_plug *plug = current->plug;
 	const int is_sync = op_is_sync(bio->bi_opf);
+	unsigned int integrity_action;
 	struct blk_mq_hw_ctx *hctx;
 	unsigned int nr_segs;
 	struct request *rq;
···
 	if (!bio)
 		goto queue_exit;
 
-	if (!bio_integrity_prep(bio))
-		goto queue_exit;
+	integrity_action = bio_integrity_action(bio);
+	if (integrity_action)
+		bio_integrity_prep(bio, integrity_action);
 
 	blk_mq_bio_issue_init(q, bio);
 	if (blk_mq_attempt_bio_merge(q, bio, nr_segs))

drivers/nvdimm/btt.c

···
 {
 	struct bio_integrity_payload *bip = bio_integrity(bio);
 	struct btt *btt = bio->bi_bdev->bd_disk->private_data;
+	unsigned int integrity_action;
 	struct bvec_iter iter;
 	unsigned long start;
 	struct bio_vec bvec;
 	int err = 0;
 	bool do_acct;
 
-	if (!bio_integrity_prep(bio))
-		return;
+	integrity_action = bio_integrity_action(bio);
+	if (integrity_action)
+		bio_integrity_prep(bio, integrity_action);
 
 	do_acct = blk_queue_io_stat(bio->bi_bdev->bd_disk->queue);
 	if (do_acct)

include/linux/bio-integrity.h

···
 int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter);
 int bio_integrity_map_iter(struct bio *bio, struct uio_meta *meta);
 void bio_integrity_unmap_user(struct bio *bio);
-bool bio_integrity_prep(struct bio *bio);
+void bio_integrity_prep(struct bio *bio, unsigned int action);
 void bio_integrity_advance(struct bio *bio, unsigned int bytes_done);
 void bio_integrity_trim(struct bio *bio);
 int bio_integrity_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp_mask);
···
 {
 }
 
-static inline bool bio_integrity_prep(struct bio *bio)
+static inline void bio_integrity_prep(struct bio *bio, unsigned int action)
 {
-	return true;
 }
 
 static inline int bio_integrity_clone(struct bio *bio, struct bio *bio_src,

include/linux/blk-integrity.h

···
 }
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 
+enum bio_integrity_action {
+	BI_ACT_BUFFER		= (1u << 0),	/* allocate buffer */
+	BI_ACT_CHECK		= (1u << 1),	/* generate / verify PI */
+	BI_ACT_ZERO		= (1u << 2),	/* zero buffer */
+};
+
+/**
+ * bio_integrity_action - return the integrity action needed for a bio
+ * @bio:	bio to operate on
+ *
+ * Returns the mask of integrity actions (BI_ACT_*) that need to be performed
+ * for @bio.
+ */
+unsigned int __bio_integrity_action(struct bio *bio);
+static inline unsigned int bio_integrity_action(struct bio *bio)
+{
+	if (!blk_get_integrity(bio->bi_bdev->bd_disk))
+		return 0;
+	if (bio_integrity(bio))
+		return 0;
+	return __bio_integrity_action(bio);
+}
+
 #endif /* _LINUX_BLK_INTEGRITY_H */