[3.11.y.z extended stable] Patch "Btrfs: fix NULL pointer crash of deleting a seed 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: fix NULL pointer crash of deleting a seed 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

------

>From c24f85b15cbedecf931340508c99150253e85eeb Mon Sep 17 00:00:00 2001
From: Liu Bo <bo.li.liu at oracle.com>
Date: Sun, 11 May 2014 23:14:59 +0800
Subject: Btrfs: fix NULL pointer crash of deleting a seed device

commit 29cc83f69c8338ff8fd1383c9be263d4bdf52d73 upstream.

Same as normal devices, seed devices should be initialized with
fs_info->dev_root as well, otherwise we'll get a NULL pointer crash.

Cc: Chris Murphy <lists at colorremedies.com>
Reported-by: Chris Murphy <lists at colorremedies.com>
Signed-off-by: Liu Bo <bo.li.liu at oracle.com>
Signed-off-by: Chris Mason <clm at fb.com>
Cc: David Sterba <dsterba at suse.cz>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/btrfs/volumes.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index cacdb3effa35..f79b027fa0f1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5730,10 +5730,14 @@ void btrfs_init_devices_late(struct btrfs_fs_info *fs_info)
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 	struct btrfs_device *device;

-	mutex_lock(&fs_devices->device_list_mutex);
-	list_for_each_entry(device, &fs_devices->devices, dev_list)
-		device->dev_root = fs_info->dev_root;
-	mutex_unlock(&fs_devices->device_list_mutex);
+	while (fs_devices) {
+		mutex_lock(&fs_devices->device_list_mutex);
+		list_for_each_entry(device, &fs_devices->devices, dev_list)
+			device->dev_root = fs_info->dev_root;
+		mutex_unlock(&fs_devices->device_list_mutex);
+
+		fs_devices = fs_devices->seed;
+	}
 }

 static void __btrfs_reset_dev_stats(struct btrfs_device *dev)
--
1.9.1