• David Sterba's avatar
    btrfs: do not allow mounting non-subvolumes via subvol option · f9d9ef62
    David Sterba authored
    There's a missing test whether the path passed to subvol=path option
    during mount is a real subvolume, allowing any directory located in
    default subovlume to be passed and accepted for mount.
    
    (current btrfs progs prevent this early)
    $ btrfs subvol snapshot . p1-snap
    ERROR: '.' is not a subvolume
    
    (with "is subvolume?" test bypassed)
    $ btrfs subvol snapshot . p1-snap
    Create a snapshot of '.' in './p1-snap'
    
    $ btrfs subvol list -p .
    ID 258 parent 5 top level 5 path subvol
    ID 259 parent 5 top level 5 path subvol1
    ID 260 parent 5 top level 5 path default-subvol1
    ID 262 parent 5 top level 5 path p1/p1-snapshot
    ID 263 parent 259 top level 5 path subvol1/subvol1-snap
    
    The problem I see is that this makes a false impression of snapshotting the
    given subvolume but in fact snapshots the default one: a user expects outcome
    like ID 263 but in fact gets ID 262 .
    
    This patch makes mount fail with EINVAL with a message in syslog.
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.cz>
    f9d9ef62
super.c 34.3 KB