Convert from ext2/3/4 filesystem to btrfs or rollback
btrfs-convert [options] <device>
btrfs-convert is used to convert existed ext2/3/4 to btrfs filesystem, and the original filesystem image is accessible as from separate subvolume named ext2_saved as file image.
-d
Disable data checksum.
-i
Ignore xattrs and ACLs.
-n
Disable packing of small files.
-r
Roll back to ext2fs.
-l <LABEL>
set filesystem label during conversion.
-L
use label from the converted filesystem.
btrfs-convert will return 0 if no error happened. If any problems happened, 1 will be returned.