On Wed, 13 Dec 2023, Dave Chinner wrote: > On Tue, Dec 12, 2023 at 10:21:53AM -0500, Kent Overstreet wrote: > > On Tue, Dec 12, 2023 at 04:53:28PM +1100, Dave Chinner wrote: > > > Doesn't anyone else see or hear the elephant trumpeting loudly in > > > the middle of the room? > > > > > > I mean, we already have name_to_handle_at() for userspace to get a > > > unique, opaque, filesystem defined file handle for any given file. > > > It's the same filehandle that filesystems hand to the nfsd so nfs > > > clients can uniquely identify the file they are asking the nfsd to > > > operate on. > > > > > > The contents of these filehandles is entirely defined by the file > > > system and completely opaque to the user. The only thing that > > > parses the internal contents of the handle is the filesystem itself. > > > Therefore, as long as the fs encodes the information it needs into the > > > handle to determine what subvol/snapshot the inode belongs to when > > > the handle is passed back to it (e.g. from open_by_handle_at()) then > > > nothing else needs to care how it is encoded. > > > > > > So can someone please explain to me why we need to try to re-invent > > > a generic filehandle concept in statx when we already have a > > > have working and widely supported user API that provides exactly > > > this functionality? > > > > Definitely should be part of the discussion :) > > > > But I think it _does_ need to be in statx; because: > > - we've determined that 64 bit ino_t just isn't a future proof > > interface, we're having real problems with it today > > - statx is _the_ standard, future proofed interface for getting inode > > attributes > > No, it most definitely isn't, and statx was never intended as a > dumping ground for anything and everything inode related. e.g. Any > inode attribute that can be modified needs to use a different > interface - one that has a corresponding "set" operation. stx_size, stx_mtime, stx_atime, stx_mode, stx_owner, stx_group, stx_nlink, .... These can all be modified but don't have matched get and set operations. stx_handle, of course, cannot be modified. I think I must be completely misunderstanding you, because the way I read your words, they don't make any sense at all. Help! NeilBrown
