Re: [PATCH 0/3] show orphan file inode detail info

["Theodore Tso" <tytso@mit.edu>]

On Tue, Apr 07, 2026 at 12:29:23PM +0200, Jan Kara wrote:
> I agree listing orphan inodes for a superblock is useful and the usefulness
> could actually go beyond ext4. I imagine the very same problem is there for
> XFS or btrfs so perhaps we could think for a while whether we can provide
> an interface that wouldn't be ext4 specific? Perhaps an ioctl
> (GET_ORPHAN_FILES) that would return an fd and reading from that fd would
> return entries for orphan inodes?

I'm really not a fan of ioctl's returning a fd, but that does seem to
be a thing these days, for better or for worse, and I agree that
having a portable solution that works across multiple file systems
would be a good thing.

> Also regarding information reported about orphan inodes - won't it be better
> interface to just return a list of file handles? Userspace can then do
> whatever it needs with them - open, statx, calling ioctl, etc - so we
> thwart feature creep with people asking us to add more information to the
> interface. This also offloads a lot of security questions about the
> interface to appropriate syscalls. So overall it looks like a win to me.

The problem with using a file handle is that the only way to get the
pathname is to open the file handle, and then call readlink on
/proc/self/fd/NN.  And inodes on the orphan inode list have been
unlinked, so we don't want to allow people to be able to open them.  I
suppose we could allow this via O_PATH, but I'm not sure that this is
guaranteed to work across all filesystems' file handles?

	      	   	      		   - Ted