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Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available

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On Mon, May 09, 2016 at 08:02:58AM -0400, Jeff Layton wrote:
> > > AT_FORCE_ATTR_SYNC can be set in flags.????This will require a network
> > > filesystem to synchronise its attributes with the server.
> > > 
> > > AT_NO_ATTR_SYNC can be set in flags.????This will suppress synchronisation
> > > with the server in a network filesystem.????The resulting values should be
> > > considered approximate.
> > 
> > And what happens if neither is set?
> > 
> 
> I'd suggest we have the documentation state that the lack of either
> flag leaves it up to the filesystem. In the case of NFS, you'd get
> "normal" attribute cache behavior, for instance which is governed by
> the ac* attributes.
> 
> We should also note that in the case of something like AT_NO_ATTR_SYNC
> on NFS, you might _still_ end up talking to the server if the client
> has nothing in-core for that inode.

File systems specific "legacy" defaults are a bad idea.  If we can't
describe the semantics we should not allow them, never mind making
the the default.  I'd strongly suggest picking one of the above flags
as the default behavior and only allowing the other as optional flag.
I suspect NO_SYNC is the better one for the flag, as otherwise people
will be surprised once they test their default case on a network
filesystem.

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[RFC][PATCH 0/6] Enhanced file stat system call David Howells <dhowells@redhat.com> - 2016-04-29 15:00 +0200
  [PATCH 4/6] statx: NFS: Return enhanced file attributes David Howells <dhowells@redhat.com> - 2016-04-29 15:00 +0200
    Re: [PATCH 4/6] statx: NFS: Return enhanced file attributes Andreas Dilger <adilger@dilger.ca> - 2016-05-03 00:50 +0200
  [PATCH 6/6] statx: CIFS: Return enhanced attributes David Howells <dhowells@redhat.com> - 2016-04-29 15:00 +0200
  [PATCH 3/6] statx: Ext4: Return enhanced file attributes David Howells <dhowells@redhat.com> - 2016-04-29 15:00 +0200
    Re: [PATCH 3/6] statx: Ext4: Return enhanced file attributes Andreas Dilger <adilger@dilger.ca> - 2016-05-03 00:50 +0200
      Re: [PATCH 3/6] statx: Ext4: Return enhanced file attributes David Howells <dhowells@redhat.com> - 2016-05-03 22:30 +0200
    Re: [PATCH 3/6] statx: Ext4: Return enhanced file attributes Christoph Hellwig <hch@infradead.org> - 2016-05-08 10:40 +0200
  [PATCH 5/6] statx: Make windows attributes available for CIFS,  NTFS and FAT to use David Howells <dhowells@redhat.com> - 2016-04-29 15:10 +0200
    Re: [PATCH 5/6] statx: Make windows attributes available for CIFS, NTFS and FAT to use Andreas Dilger <adilger@dilger.ca> - 2016-05-03 01:00 +0200
      Re: [PATCH 5/6] statx: Make windows attributes available for CIFS, NTFS and FAT to use David Howells <dhowells@redhat.com> - 2016-05-03 22:30 +0200
    Re: [PATCH 5/6] statx: Make windows attributes available for CIFS,  NTFS and FAT to use Christoph Hellwig <hch@infradead.org> - 2016-05-08 10:40 +0200
  [PATCH 2/6] statx: AFS: Return enhanced file attributes David Howells <dhowells@redhat.com> - 2016-04-29 15:20 +0200
  Re: [RFC][PATCH 0/6] Enhanced file stat system call Jeff Layton <jlayton@poochiereds.net> - 2016-04-30 23:10 +0200
  Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-03 18:00 +0200
  Re: [RFC][PATCH 0/6] Enhanced file stat system call Arnd Bergmann <arnd@arndb.de> - 2016-05-04 15:50 +0200
    Re: [RFC][PATCH 0/6] Enhanced file stat system call Steve French <smfrench@gmail.com> - 2016-05-06 04:10 +0200
      Re: [RFC][PATCH 0/6] Enhanced file stat system call Arnd Bergmann <arnd@arndb.de> - 2016-05-09 15:10 +0200
  Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Dave Chinner <david@fromorbit.com> - 2016-05-05 01:00 +0200
    Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available NeilBrown <nfbrown@novell.com> - 2016-05-05 02:20 +0200
      Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Jeff Layton <jlayton@poochiereds.net> - 2016-05-05 21:50 +0200
        Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-05 22:10 +0200
          Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Dave Chinner <david@fromorbit.com> - 2016-05-06 03:50 +0200
        Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available bfields@fieldses.org (J. Bruce Fields) - 2016-05-06 20:10 +0200
    Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available bfields@fieldses.org (J. Bruce Fields) - 2016-05-06 20:30 +0200
      Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Dave Chinner <david@fromorbit.com> - 2016-05-09 03:50 +0200
        Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available "J. Bruce Fields" <bfields@fieldses.org> - 2016-05-09 04:50 +0200
  Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available NeilBrown <nfbrown@novell.com> - 2016-05-05 02:00 +0200
  Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Christoph Hellwig <hch@infradead.org> - 2016-05-08 10:40 +0200
    Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Jeff Layton <jlayton@poochiereds.net> - 2016-05-09 14:10 +0200
      Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Christoph Hellwig <hch@infradead.org> - 2016-05-10 09:10 +0200
        Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Jeff Layton <jlayton@poochiereds.net> - 2016-05-10 15:30 +0200
    Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-09 15:00 +0200
      Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-09 15:10 +0200
      Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Trond Myklebust <trondmy@primarydata.com> - 2016-05-09 15:40 +0200
      Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Christoph Hellwig <hch@infradead.org> - 2016-05-10 09:10 +0200
        Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-10 10:30 +0200
          Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Christoph Hellwig <hch@infradead.org> - 2016-05-12 11:20 +0200
    Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-09 15:40 +0200
      Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Christoph Hellwig <hch@infradead.org> - 2016-05-10 09:10 +0200
        Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-10 10:50 +0200
          Re: [PATCH 1/6] statx: Add a system call to make enhanced file info  available Christoph Hellwig <hch@infradead.org> - 2016-05-12 11:20 +0200
    Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available David Howells <dhowells@redhat.com> - 2016-05-09 15:50 +0200

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