The commit 6f7151f499 extended the set of recognized valid subcommands
for the old path syntax but wrongly checks for more than 2 parameters.
That way a shortened and valid new syntax is not recognized (here 'can'
is short for 'cancel' and the short form is not in the list):
btrfs-progs-6.1.3
btrfs bal can /
ERROR: balance cancel on '/' failed: Not in progress
btrfs-progs-6.2.2
btrfs bal can /
WARNING: deprecated syntax, please use 'btrfs balance start'
ERROR: cannot access 'can': No such file or directory
Issue: #612
Fixes: 6f7151f499 ("btrfs-progs: balance: fix some cases wrongly parsed as old syntax")
Signed-off-by: David Sterba <dsterba@suse.com>
9cb34031d7