Current 'man btrfs-replace' is as follows:
========================================================================
...
...
-f
force using and overwriting <targetdev> even if it looks like
containing a valid btrfs filesystem.
A valid filesystem is assumed if a btrfs superblock is found
which contains a correct checksum. Devices which are currently
mounted are never allowed to be used as the <targetdev>. -B::::
no background replace.
...
...
========================================================================
The format of 'B' option is wrong. So, fix it.
Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
A valid filesystem is assumed if a btrfs superblock is found which contains a
correct checksum. Devices which are currently mounted are
never allowed to be used as the <targetdev>.
++
-B::::
no background replace.