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authorChristoph Hellwig <hch@lst.de>2019-08-12 17:39:56 +0200
committerJens Axboe <axboe@kernel.dk>2019-08-22 07:14:36 -0600
commit320ea869a12cec206756207c6ca5f817ec45c7f2 (patch)
treef47241df847ce8a065edf328cf94794e8f4694c0 /block
parente9e006f5fcf2bab59149cb38a48a4817c1b538b4 (diff)
downloadlinux-320ea869a12cec206756207c6ca5f817ec45c7f2.tar.gz
block: improve the gap check in __bio_add_pc_page
If we can add more data into an existing segment we do not create a gap
per definition, so move the check for a gap after the attempt to merge
into the segment.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/bio.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/block/bio.c b/block/bio.c
index 54769659a434..537d71a30e56 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -710,18 +710,18 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
 			goto done;
 		}
 
-		/*
-		 * If the queue doesn't support SG gaps and adding this
-		 * offset would create a gap, disallow it.
-		 */
-		if (bvec_gap_to_prev(q, bvec, offset))
-			return 0;
-
 		if (page_is_mergeable(bvec, page, len, offset, &same_page) &&
 		    can_add_page_to_seg(q, bvec, page, len, offset)) {
 			bvec->bv_len += len;
 			goto done;
 		}
+
+		/*
+		 * If the queue doesn't support SG gaps and adding this segment
+		 * would create a gap, disallow it.
+		 */
+		if (bvec_gap_to_prev(q, bvec, offset))
+			return 0;
 	}
 
 	if (bio_full(bio, len))