RAID1 root filesystem - same device shows up twice in 'btrfs fi show'

[Scott Talbert <swt@techie.net>]

Hi,

I'm using:

Kernel 4.2.6
btrfs-progs v4.3
Debian Wheezy

I have a RAID1 root filesystem with two devices.  When the system 
initially boots up, "btrfs fi show" will show the same device twice:

Label: none  uuid: 49f7413a-99ad-41b0-8783-06c9406e2280
 	Total devices 2 FS bytes used 1.19GiB
 	devid    1 size 7.60GiB used 3.03GiB path /dev/sdf2
 	devid    2 size 7.60GiB used 3.01GiB path /dev/sdf2

The filesystem seems to work fine (as best as I can tell) in this state. 
If I then run another "btrfs device scan", it will correct itself:

Label: none  uuid: 49f7413a-99ad-41b0-8783-06c9406e2280
         Total devices 2 FS bytes used 1.19GiB
         devid    1 size 7.60GiB used 3.03GiB path /dev/sde2
         devid    2 size 7.60GiB used 3.01GiB path /dev/sdf2

Any idea what might be going on here?  On Debian it appears that the 
initial "btrfs device scan" is being done by an initramfs local-premount 
script where it does:

modprobe btrfs
/bin/btrfs device scan 2>/dev/null

Does there perhaps need to be some delay between inserting the kernel 
module and running a scan?

Thanks,
Scott