From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [PATCH 004 of 5] md: Improve detection of lack of barrier support in raid1 Date: Fri, 28 Apr 2006 12:51:50 +1000 Message-ID: <1060428025150.30782@suse.de> References: <20060428124313.29510.patches@notabene> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-raid.ids Move the test for 'do barrier work' down a bit so that if the first write to a raid1 is a BIO_RW_BARRIER write, the checking done by superblock writes will cause the right thing to happen. Signed-off-by: Neil Brown ### Diffstat output ./drivers/md/raid1.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff ./drivers/md/raid1.c~current~ ./drivers/md/raid1.c --- ./drivers/md/raid1.c~current~ 2006-04-28 12:17:27.000000000 +1000 +++ ./drivers/md/raid1.c 2006-04-28 12:17:40.000000000 +1000 @@ -753,18 +753,24 @@ static int make_request(request_queue_t const int rw = bio_data_dir(bio); int do_barriers; - if (unlikely(!mddev->barriers_work && bio_barrier(bio))) { - bio_endio(bio, bio->bi_size, -EOPNOTSUPP); - return 0; - } - /* * Register the new request and wait if the reconstruction * thread has put up a bar for new requests. * Continue immediately if no resync is active currently. + * We test barriers_work *after* md_write_start as md_write_start + * may cause the first superblock write, and that will check out + * if barriers work. */ + md_write_start(mddev, bio); /* wait on superblock update early */ + if (unlikely(!mddev->barriers_work && bio_barrier(bio))) { + if (rw == WRITE) + md_write_end(mddev); + bio_endio(bio, bio->bi_size, -EOPNOTSUPP); + return 0; + } + wait_barrier(conf); disk_stat_inc(mddev->gendisk, ios[rw]);