On Wed, Aug 12, 2020 at 06:39:11PM +0100, Al Viro wrote:

On Wed, Aug 12, 2020 at 07:16:37PM +0200, Miklos Szeredi wrote:

quoted

On Wed, Aug 12, 2020 at 6:33 PM Al Viro [off-list ref] wrote:

quoted

On Wed, Aug 12, 2020 at 05:13:14PM +0200, Miklos Szeredi wrote:

quoted

quoted

Why does it have to have a struct mount?  It does not have to use
dentry/mount based path lookup.

What the fuck?  So we suddenly get an additional class of objects
serving as kinda-sorta analogues of dentries *AND* now struct file
might refer to that instead of a dentry/mount pair - all on the VFS
level?  And so do all the syscalls you want to allow for such "pathnames"?

The only syscall I'd want to allow is open, everything else would be
on the open files themselves.

file->f_path can refer to an anon mount/inode, the real object is
referred to by file->private_data.

The change to namei.c would be on the order of ~10 lines.  No other
parts of the VFS would be affected.

If some of the things you open are directories (and you *have* said that
directories will be among those just upthread, and used references to
readdir() as argument in favour of your approach elsewhere in the thread),
you will have to do something about fchdir().  And that's the least of
the issues.

BTW, what would such opened files look like from /proc/*/fd/* POV?  And
what would happen if you walk _through_ that symlink, with e.g. ".."
following it?  Or with names of those attributes, for that matter...
What about a normal open() of such a sucker?  It won't know where to
look for your ->private_data...

FWIW, you keep refering to regularity of this stuff from the syscall
POV, but it looks like you have no real idea of what subset of the
things available for normal descriptors will be available for those.