[3.8.y.z extended stable] Patch "Btrfs: skip submitting barrier for missing device" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    Btrfs: skip submitting barrier for missing device

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.22.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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>From 30012954274818d863266d735429657f3cca779b Mon Sep 17 00:00:00 2001
From: Hidetoshi Seto <seto.hidetoshi at jp.fujitsu.com>
Date: Wed, 5 Feb 2014 16:34:38 +0900
Subject: Btrfs: skip submitting barrier for missing device

commit f88ba6a2a44ee98e8d59654463dc157bb6d13c43 upstream.

I got an error on v3.13:
 BTRFS error (device sdf1) in write_all_supers:3378: errno=-5 IO failure (errors while submitting device barriers.)

how to reproduce:
  > mkfs.btrfs -f -d raid1 /dev/sdf1 /dev/sdf2
  > wipefs -a /dev/sdf2
  > mount -o degraded /dev/sdf1 /mnt
  > btrfs balance start -f -sconvert=single -mconvert=single -dconvert=single /mnt

The reason of the error is that barrier_all_devices() failed to submit
barrier to the missing device.  However it is clear that we cannot do
anything on missing device, and also it is not necessary to care chunks
on the missing device.

This patch stops sending/waiting barrier if device is missing.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi at jp.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik at fb.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/btrfs/disk-io.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a8f652d..5bb5f7c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2985,6 +2985,8 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
 	/* send down all the barriers */
 	head = &info->fs_devices->devices;
 	list_for_each_entry_rcu(dev, head, dev_list) {
+		if (dev->missing)
+			continue;
 		if (!dev->bdev) {
 			errors_send++;
 			continue;
@@ -2999,6 +3001,8 @@ static int barrier_all_devices(struct btrfs_fs_info *info)

 	/* wait for all the barriers */
 	list_for_each_entry_rcu(dev, head, dev_list) {
+		if (dev->missing)
+			continue;
 		if (!dev->bdev) {
 			errors_wait++;
 			continue;
--
1.9.1