Description of problem:
Create a btrfs partition across multiple devices, unload btrfs module, then the mount will fail (btrfs module will be loaded automatically). But mounting btrfs on single device will be done without problems(of cause, without btrfs module loaded)

After this failure mount, all mount will fail even with btrfs module loaded. I have to do btrfsck to make the partition mounted.

Version-Release number of selected component (if applicable):
kernel-2.6.32-59.1.el6.x86_64
btrfs-progs-0.19-11.el6.x86_64

How reproducible:
always

Steps to Reproduce:
# Make sure btrfs is unloaded
modprobe -r btrfs

mkdir -p /mnt/btrfs
dd if=/dev/null of=/home/img0 bs=1G seek=5
dd if=/dev/null of=/home/img1 bs=1G seek=3
for i in 0 1;do losetup /dev/loop$i /home/img$i;done
mkfs.btrfs /dev/loop0 /dev/loop1

mount /dev/loop0 /mnt/btrfs
  
Actual results:
[root@dell-per810-01 ~]# mount /dev/loop0 /mnt/btrfs
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

[root@dell-per810-01 ~]# dmesg | tail
[snip]
Btrfs loaded
device fsid f14ed90116772672-7a80a1b42439d7b3 devid 1 transid 7 /dev/loop0
btrfs: failed to read the system array on loop0
btrfs: open_ctree failed

Expected results:
Mount successfully

Additional info: