[RFC PATCH 4/4] block: add support to pass the meta buffer

[Kanchan Joshi <joshi.k@xxxxxxxxxxx>]

If IOCB_USE_META flag is set, iocb->private points to iov_iter
corresponding to the meta-buffer.
Use it to prepare the bip and attach that to the bio that we send down.

Make sure that block-integrity checks are skipped for this user-owned
meta buffer.

Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
---
 block/bio-integrity.c | 13 +++++++++++++
 block/fops.c          |  9 +++++++++
 block/t10-pi.c        |  6 ++++++
 include/linux/bio.h   |  6 ++++++
 4 files changed, 34 insertions(+)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index e340b5a03cdf..c46b70aff840 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -308,6 +308,19 @@ static unsigned int bvec_from_pages(struct bio_vec *bvec, struct page **pages,
 	return nr_bvecs;
 }
 
+int bio_integrity_map_iter(struct bio *bio, struct iov_iter *iter)
+{
+	struct blk_integrity *bi = blk_get_integrity(bio->bi_bdev->bd_disk);
+
+	if (!bi)
+		return -EINVAL;
+
+	if (iter->count < bio_integrity_bytes(bi, bio_sectors(bio)))
+		return -EINVAL;
+
+	return bio_integrity_map_user(bio, iter, 0);
+}
+
 int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter,
 			  u32 seed)
 {
diff --git a/block/fops.c b/block/fops.c
index 679d9b752fe8..e488fa66dd60 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -353,6 +353,15 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
 		task_io_account_write(bio->bi_iter.bi_size);
 	}
 
+	if (unlikely(iocb->ki_flags & IOCB_USE_META)) {
+		ret = bio_integrity_map_iter(bio, iocb->private);
+		WRITE_ONCE(iocb->private, NULL);
+		if (unlikely(ret)) {
+			bio_put(bio);
+			return ret;
+		}
+	}
+
 	if (iocb->ki_flags & IOCB_NOWAIT)
 		bio->bi_opf |= REQ_NOWAIT;
 
diff --git a/block/t10-pi.c b/block/t10-pi.c
index d90892fd6f2a..72d1522417a1 100644
--- a/block/t10-pi.c
+++ b/block/t10-pi.c
@@ -156,6 +156,8 @@ static void t10_pi_type1_prepare(struct request *rq)
 		/* Already remapped? */
 		if (bip->bip_flags & BIP_MAPPED_INTEGRITY)
 			break;
+		if (bip->bip_flags & BIP_INTEGRITY_USER)
+			break;
 
 		bip_for_each_vec(iv, bip, iter) {
 			unsigned int j;
@@ -205,6 +207,8 @@ static void t10_pi_type1_complete(struct request *rq, unsigned int nr_bytes)
 		struct bio_vec iv;
 		struct bvec_iter iter;
 
+		if (bip->bip_flags & BIP_INTEGRITY_USER)
+			break;
 		bip_for_each_vec(iv, bip, iter) {
 			unsigned int j;
 			void *p;
@@ -408,6 +412,8 @@ static void ext_pi_type1_prepare(struct request *rq)
 		/* Already remapped? */
 		if (bip->bip_flags & BIP_MAPPED_INTEGRITY)
 			break;
+		if (bip->bip_flags & BIP_INTEGRITY_USER)
+			break;
 
 		bip_for_each_vec(iv, bip, iter) {
 			unsigned int j;
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 20cf47fc851f..34ea387dfc59 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -723,6 +723,7 @@ static inline bool bioset_initialized(struct bio_set *bs)
 	for_each_bio(_bio)						\
 		bip_for_each_vec(_bvl, _bio->bi_integrity, _iter)
 
+int bio_integrity_map_iter(struct bio *bio, struct iov_iter *iter);
 int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter, u32 seed);
 extern struct bio_integrity_payload *bio_integrity_alloc(struct bio *, gfp_t, unsigned int);
 extern int bio_integrity_add_page(struct bio *, struct page *, unsigned int, unsigned int);
@@ -802,6 +803,11 @@ static inline int bio_integrity_map_user(struct bio *bio, struct iov_iter *iter,
 	return -EINVAL;
 }
 
+static inline int bio_integrity_map_iter(struct bio *bio, struct iov_iter *iter)
+{
+	return -EINVAL;
+}
+
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 
 /*
-- 
2.25.1