[3.11.y.z extended stable] Patch "Btrfs: set right total device count for seeding support" 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: set right total device count for seeding support

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 be1e52fe27553c39a39c1c04fea32501f416ab3c Mon Sep 17 00:00:00 2001
From: Wang Shilong <wangsl.fnst at cn.fujitsu.com>
Date: Tue, 13 May 2014 17:05:06 +0800
Subject: Btrfs: set right total device count for seeding support

commit 298658414a2f0bea1f05a81876a45c1cd96aa2e0 upstream.

Seeding device support allows us to create a new filesystem
based on existed filesystem.

However newly created filesystem's @total_devices should include seed
devices. This patch fix the following problem:

 # mkfs.btrfs -f /dev/sdb
 # btrfstune -S 1 /dev/sdb
 # mount /dev/sdb /mnt
 # btrfs device add -f /dev/sdc /mnt --->fs_devices->total_devices = 1
 # umount /mnt
 # mount /dev/sdc /mnt               --->fs_devices->total_devices = 2

This is because we record right @total_devices in superblock, but
@fs_devices->total_devices is reset to be 0 in btrfs_prepare_sprout().

Fix this problem by not resetting @fs_devices->total_devices.

Signed-off-by: Wang Shilong <wangsl.fnst at cn.fujitsu.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 | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f79b027fa0f1..ca9a51400035 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1844,7 +1844,6 @@ static int btrfs_prepare_sprout(struct btrfs_root *root)
 	fs_devices->seeding = 0;
 	fs_devices->num_devices = 0;
 	fs_devices->open_devices = 0;
-	fs_devices->total_devices = 0;
 	fs_devices->seed = seed_devices;

 	generate_random_uuid(fs_devices->fsid);
--
1.9.1