[PATCH 3.11 037/182] Btrfs: skip submitting barrier for missing device

[Luis Henriques]

3.11.10.9 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hidetoshi Seto <seto.hidetoshi at jp.fujitsu.com>

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