btrfs-progs: receive: better error reporting for snapshots
Two fixes:
1)
Check that the parent subvol actually is reachable via our root path.
The previous code wouldn't catch
parent subvol: foo/bar
root path: bar (i.e. mounted with -o subvol=bar)
where the parent isn't reachable from the root path.
(but the original "strstr(parent, root_path) == NULL" check still doesn't hold)
Also check for the slash after "root_path", i.e. throw an error on
parent subvol: foobar
root path: foo
2)
If the parent subvol is the one that is mounted we obviously can't
receive into it, as it has to be read-only by definition.
We'd get a rather cryptic:
At subvol /tmp/test/dest.snap
At snapshot dest.snap
ERROR: creating snapshot / -> dest.snap failed: Invalid cross-device link
(not sure what it says if "/" isn't even a btrfs)
But with this we get
At subvol /tmp/test/dest.snap
At snapshot dest.snap
ERROR: creating snapshot . -> dest.snap failed: Read-only file system
which is both more helpful and more correct.
Signed-off-by: Benedikt Morbach <benedikt.morbach@googlemail.com>
Signed-off-by: David Sterba <dsterba@suse.com>