raw fs backup/copy

["Ivan Labáth" <ilabath@gmail.com>]

Is there a reason one can not mount a btrfs and it's byte-for-byte
copy in parallel, or is the driver just acting silly?

Mini example:
# dd if=/dev/zero of=fs1 bs=1 count=1 seek=$((1024*1024*1024-1))
# mkfs.btrfs fs1
# cp --sparse=always fs1 fs2
# mkdir 1 2
# mount fs1 1 -o loop
# mount fs2 2 -o loop
# touch 1/1
# ls 2
1
# cat /proc/mounts
/dev/loop0 /tmp/test/1 btrfs rw,relatime 0 0
/dev/loop1 /tmp/test/2 btrfs rw,relatime 0 0

--
ivan