>From 92a97ef181e15caa94bd56a1ade5c337db599b79 Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Tue, 26 Jan 2010 16:01:34 +0300 Subject: [PATCH] [PATCH] block: fix bio_add_page for non trivial merge_bvec_fn case We have to properly decrease bi_size in order to merge_bvec_fn return right result. Otherwise this result in false merge rejects for two absolutely valid bio_vecs. This may cause significant performance penalty for example Itanium: page_size == 16k, fs_block_size == 1k and block device is raid with small chunk_size. Signed-off-by: Dmitry Monakhov --- fs/bio.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/fs/bio.c b/fs/bio.c index 76e6713..9f8e517 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -548,7 +548,8 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page struct bvec_merge_data bvm = { .bi_bdev = bio->bi_bdev, .bi_sector = bio->bi_sector, - .bi_size = bio->bi_size, + .bi_size = bio->bi_size - + (prev->bv_len - len), .bi_rw = bio->bi_rw, }; -- 1.6.3.3