From: Bernd Schubert Subject: bio_add_page rw mode check by merge_bvec_fn Date: Thu, 21 Nov 2013 19:00:48 +0100 Message-ID: <528E4A50.7040609@itwm.fraunhofer.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Kent Overstreet , NeilBrown , Jens Axboe To: fsdevel@fhgfs.com, xfs@oss.sgi.com, linux-ext4@vger.kernel.org Return-path: Received: from mailgw1.uni-kl.de ([131.246.120.220]:37970 "EHLO mailgw1.uni-kl.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751373Ab3KUSAy (ORCPT ); Thu, 21 Nov 2013 13:00:54 -0500 Received: from itwm2.itwm.fhg.de (itwm2.itwm.fhg.de [131.246.191.3]) by mailgw1.uni-kl.de (8.14.3/8.14.3/Debian-9.4) with ESMTP id rALI0pcR023151 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT) for ; Thu, 21 Nov 2013 19:00:51 +0100 Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi all, raid5_mergeable_bvec() (q->merge_bvec_fn) checks for the rw-type and makes decisions based on that if the bio is mergable or not. But so far this value is only initialized on calling submit_bio(), at least not by ext4 and xfs. I have not checked other file system so far. Question 1: merge_bvec_fn is supposed to be removed, is is still worth to fix the usage of merge_bvec_fn? Question 2: If it is still supposed to be fixed, how do want to have it? So far I have two patches for xfs and ext4 to set the rw type directly there, but maybe bio_add_page should get an int rw_type parameter and set bio->bi_rw itself? diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index d488f80..4cddc15 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -370,6 +370,7 @@ static int io_submit_init_bio(struct ext4_io_submit *io, bio->bi_bdev = bh->b_bdev; bio->bi_end_io = ext4_end_bio; bio->bi_private = ext4_get_io_end(io->io_end); + bio->bi_rw |= io->io_op; io->io_bio = bio; io->io_next_block = bh->b_blocknr; return 0; diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 71c8c9d..b48048f 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -401,7 +401,8 @@ xfs_submit_ioend_bio( STATIC struct bio * xfs_alloc_ioend_bio( - struct buffer_head *bh) + struct buffer_head *bh, + struct writeback_control *wbc) { int nvecs = bio_get_nr_vecs(bh->b_bdev); struct bio *bio = bio_alloc(GFP_NOIO, nvecs); @@ -409,6 +410,7 @@ xfs_alloc_ioend_bio( ASSERT(bio->bi_private == NULL); bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); bio->bi_bdev = bh->b_bdev; + bio->bi_rw |= (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE; return bio; } @@ -511,7 +513,8 @@ xfs_submit_ioend( if (!bio) { retry: - bio = xfs_alloc_ioend_bio(bh); + bio = xfs_alloc_ioend_bio(bh, wbc); + } else if (bh->b_blocknr != lastblock + 1) { xfs_submit_ioend_bio(wbc, ioend, bio); goto retry; Thanks, Bernd