From 102ed2c5ff932439bbbe74c7bd63e6d5baa9f732 Mon Sep 17 00:00:00 2001 From: Anand Jain Date: Sat, 14 Oct 2017 08:34:02 +0800 Subject: [PATCH] btrfs: fix false EIO for missing device MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When one of the device is missing, bbio_error() takes care of setting the error status. And if its only IO that is pending in that stripe, it fails to check the status of the other IO at %bbio_error before setting the error %bi_status for the %orig_bio. Fix this by checking if %bbio->error has exceeded the %bbio->max_errors. Reproducer as below fdatasync error is seen intermittently. mount -o degraded /dev/sdc /btrfs dd status=none if=/dev/zero of=$(mktemp /btrfs/XXX) bs=4096 count=1 conv=fdatasync dd: fdatasync failed for ‘/btrfs/LSe’: Input/output error The reason for the intermittences of the problem is because the following conditions have to be met, which depends on timing: In btrfs_map_bio() - the RAID1 the missing device has to be at %dev_nr = 1 In bbio_error() . before bbio_error() is called the bio of the not-missing device at %dev_nr = 0 must be completed so that the below condition is true if (atomic_dec_and_test(&bbio->stripes_pending)) { Signed-off-by: Anand Jain Reviewed-by: Liu Bo Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6df39b5fda89..11d7707a3fb3 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -6129,7 +6129,10 @@ static void bbio_error(struct btrfs_bio *bbio, struct bio *bio, u64 logical) btrfs_io_bio(bio)->mirror_num = bbio->mirror_num; bio->bi_iter.bi_sector = logical >> 9; - bio->bi_status = BLK_STS_IOERR; + if (atomic_read(&bbio->error) > bbio->max_errors) + bio->bi_status = BLK_STS_IOERR; + else + bio->bi_status = BLK_STS_OK; btrfs_end_bbio(bbio, bio); } } -- 2.25.1