[Xen-devel] [PATCH 08/13] block: add a missing BIOVEC_SEG_BOUNDARY check in bio_add_pc_page

[Christoph Hellwig <hch@xxxxxx>]

The actual recaculation of segments in __blk_recalc_rq_segments will
do this check, so there is no point in forcing it if we know it won't
succeed.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 block/bio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/bio.c b/block/bio.c
index 7f7230140b66..d15a228d1bfc 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -729,7 +729,9 @@ int bio_add_pc_page(struct request_queue *q, struct bio 
*bio, struct page
        }
 
        /* If we may be able to merge these biovecs, force a recount */
-       if (bio->bi_vcnt > 1 && biovec_phys_mergeable(bvec-1, bvec))
+       if (bio->bi_vcnt > 1 &&
+           biovec_phys_mergeable(bvec - 1, bvec) &&
+           BIOVEC_SEG_BOUNDARY(q, bvec - 1, bvec))
                bio_clear_flag(bio, BIO_SEG_VALID);
 
  done:
-- 
2.18.0


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