[PATCH v7 02/10] block: copy back bounce buffer to user-space correctly in case of split

[Anuj Gupta <anuj20.g@samsung.com>]

From: Christoph Hellwig <hch@lst.de>

Copy back the bounce buffer to user-space in entirety when the parent
bio completes. The existing code uses bip_iter.bi_size for sizing the
copy, which can be modified. So move away from that and fetch it from
the vector passed to the block layer. While at it, switch to using
better variable names.

Fixes: 492c5d455969f ("block: bio-integrity: directly map user buffers")
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
[hch: better names for variables]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
---
 block/bio-integrity.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index a448a25d13de..4341b0d4efa1 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -118,17 +118,18 @@ static void bio_integrity_unpin_bvec(struct bio_vec *bv, int nr_vecs,
 
 static void bio_integrity_uncopy_user(struct bio_integrity_payload *bip)
 {
-	unsigned short nr_vecs = bip->bip_max_vcnt - 1;
-	struct bio_vec *copy = &bip->bip_vec[1];
-	size_t bytes = bip->bip_iter.bi_size;
-	struct iov_iter iter;
+	unsigned short orig_nr_vecs = bip->bip_max_vcnt - 1;
+	struct bio_vec *orig_bvecs = &bip->bip_vec[1];
+	struct bio_vec *bounce_bvec = &bip->bip_vec[0];
+	size_t bytes = bounce_bvec->bv_len;
+	struct iov_iter orig_iter;
 	int ret;
 
-	iov_iter_bvec(&iter, ITER_DEST, copy, nr_vecs, bytes);
-	ret = copy_to_iter(bvec_virt(bip->bip_vec), bytes, &iter);
+	iov_iter_bvec(&orig_iter, ITER_DEST, orig_bvecs, orig_nr_vecs, bytes);
+	ret = copy_to_iter(bvec_virt(bounce_bvec), bytes, &orig_iter);
 	WARN_ON_ONCE(ret != bytes);
 
-	bio_integrity_unpin_bvec(copy, nr_vecs, true);
+	bio_integrity_unpin_bvec(orig_bvecs, orig_nr_vecs, true);
 }
 
 /**
-- 
2.25.1