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

[Luis Henriques]

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-3.11.y-queue branch of the 3.11.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-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 6df7d3d03f7b1c5beaa7e2304f4b45dd2770c6d4 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: Luis Henriques <luis.henriques 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 6b092a1..3ce4436 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3190,6 +3190,8 @@ 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;
@@ -3204,6 +3206,8 @@ 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