Btrfs: set right total device count for seeding support
authorWang Shilong <wangsl.fnst@cn.fujitsu.com>
Tue, 13 May 2014 09:05:06 +0000 (17:05 +0800)
committerChris Mason <clm@fb.com>
Tue, 10 Jun 2014 00:20:50 +0000 (17:20 -0700)
commit298658414a2f0bea1f05a81876a45c1cd96aa2e0
treedf33ffc840626aeaace2c02f6821035c9a5ddd48
parent45ff35d6b9f301cbfb6b1703466ebe4431c7567f
Btrfs: set right total device count for seeding support

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@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
fs/btrfs/volumes.c