This is a note to let you know that I've just added the patch titled
btrfs: fix false EIO for missing device
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-fix-false-eio-for-missing-device.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Dec 18 13:28:59 CET 2017
From: Anand Jain <anand.jain@xxxxxxxxxx>
Date: Sat, 14 Oct 2017 08:34:02 +0800
Subject: btrfs: fix false EIO for missing device
From: Anand Jain <anand.jain@xxxxxxxxxx>
[ Upstream commit 102ed2c5ff932439bbbe74c7bd63e6d5baa9f732 ]
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 <anand.jain@xxxxxxxxxx>
Reviewed-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/volumes.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6144,7 +6144,10 @@ static void bbio_error(struct btrfs_bio
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);
}
}
Patches currently in stable-queue which might be from anand.jain@xxxxxxxxxx are
queue-4.14/btrfs-undo-writable-superblocke-when-sprouting-fails.patch
queue-4.14/btrfs-fix-false-eio-for-missing-device.patch