linux-kernel - [PATCH 11/16] block: rewrite bio_copy_data_iter to use bvec_kmap_local and memcpy_to

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Date:   Tue,  8 Jun 2021 18:05:58 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Geoff Levand <geoff@...radead.org>,
        Ilya Dryomov <idryomov@...il.com>,
        Dongsheng Yang <dongsheng.yang@...ystack.cn>,
        Mike Snitzer <snitzer@...hat.com>,
        Ira Weiny <ira.weiny@...el.com>, dm-devel@...hat.com,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        ceph-devel@...r.kernel.org
Subject: [PATCH 11/16] block: rewrite bio_copy_data_iter to use bvec_kmap_local and memcpy_to_bvec

Use the proper helpers instead of open coding the copy.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 block/bio.c | 28 ++++++++--------------------
 1 file changed, 8 insertions(+), 20 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 1d7abdb83a39..c14d2e66c084 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1186,27 +1186,15 @@ EXPORT_SYMBOL(bio_advance);
 void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 			struct bio *src, struct bvec_iter *src_iter)
 {
-	struct bio_vec src_bv, dst_bv;
-	void *src_p, *dst_p;
-	unsigned bytes;
-
 	while (src_iter->bi_size && dst_iter->bi_size) {
-		src_bv = bio_iter_iovec(src, *src_iter);
-		dst_bv = bio_iter_iovec(dst, *dst_iter);
-
-		bytes = min(src_bv.bv_len, dst_bv.bv_len);
-
-		src_p = kmap_atomic(src_bv.bv_page);
-		dst_p = kmap_atomic(dst_bv.bv_page);
-
-		memcpy(dst_p + dst_bv.bv_offset,
-		       src_p + src_bv.bv_offset,
-		       bytes);
-
-		kunmap_atomic(dst_p);
-		kunmap_atomic(src_p);
-
-		flush_dcache_page(dst_bv.bv_page);
+		struct bio_vec src_bv = bio_iter_iovec(src, *src_iter);
+		struct bio_vec dst_bv = bio_iter_iovec(dst, *dst_iter);
+		unsigned int bytes = min(src_bv.bv_len, dst_bv.bv_len);
+		void *src_buf;
+
+		src_buf = bvec_kmap_local(&src_bv);
+		memcpy_to_bvec(&dst_bv, src_buf);
+		kunmap_local(src_buf);
 
 		bio_advance_iter_single(src, src_iter, bytes);
 		bio_advance_iter_single(dst, dst_iter, bytes);
-- 
2.30.2