From 62de608da0b0ab17d81a233b50d1e952b9816f69 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 1 May 2006 12:15:47 -0700 Subject: [PATCH] [PATCH] md: Improve detection of lack of barrier support in raid1 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/md/raid1.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 532d040..b8c13c8 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -753,18 +753,24 @@ static int make_request(request_queue_t *q, struct bio * bio) 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]); -- 2.7.4