On Tue, Apr 16, 2024 at 09:54:14AM -0700, Christoph Hellwig wrote: > On Tue, Apr 16, 2024 at 09:50:56AM -0700, Darrick J. Wong wrote: > > On Tue, Apr 16, 2024 at 06:47:16AM +0200, Christoph Hellwig wrote: > > > On Mon, Apr 15, 2024 at 12:40:36PM -0700, Darrick J. Wong wrote: > > > > True, libhandle is a very nice wrapper for the kernel ioctls. I wish > > > > Linux projects did that more often. But suppose you're calling the > > > > ioctls directly without libhandle and mess it up? > > > > > > The you get different inodes back. Not really any different from > > > pointing your path name based code to the wrong fs or directory, > > > is it? > > > > I suppose not. But why bother setting the fsid at all, then? > > I suspect that's a leftover from IRIX where the by handle operations > weren't ioctls tied to a specific file system. Oh, so on Irix a program could call the kernel with *only* the handle and no fd? I wasn't aware of that, but most of my exposure to Irix was wowwwing over the 3D File Explorer in _Jurassic Park_ and later an old Indigo that someone donated to the high school. ;) Ok, I'll drop the fsid checking code entirely. > > > But as we never generate the file handles that encode the parent > > > we already never connect files to their parent directory anyway. > > > > I pondered whether or not we should encode parent info in a regular > > file's handle. > > We shouldn't. It's a really a NFS thing. > > > > Would that result in an invalid handle if the file gets > > moved to another directory? > > Yes. > > > That doesn't seem to fit with the behavior > > that fds remain attached to the file even if it gets moved/deleted. > > Exactly. <nod> > > > > > OTOH we should be able to optimize ->get_parent a bit with parent > > > pointers, as we can find the name in the parent directory for > > > a directory instead of doing linear scans in the parent directory. > > > (for non-directory files we currenty don't fully connect anwyay) > > > > <nod> But does exportfs actually want parent info for a nondirectory? > > There aren't any stubs or XXX/FIXME comments, and I've never heard any > > calls (at least on fsdevel) for that functionality. > > It doesn't. It would avoid having disconnected dentries, but > disconnected non-directory dentries aren't really a problem. For directories, I think the dotdot lookup is much cheaper than scanning the attrs to find the first nongarbage XFS_ATTR_PARENT entry. --D
