[RFC][PATCH 06/10] cifs: define inode-level cache object and register them

Jeff Layton jlayton at samba.org
Fri Jun 25 16:26:51 MDT 2010

On Fri, 25 Jun 2010 22:46:38 +0100
David Howells <dhowells at redhat.com> wrote:

> Jeff Layton <jlayton at samba.org> wrote:
> > Looks like it mostly uses the ctime. IMO, the mtime would be a better
> > choice since it changes less frequently, but I don't guess that it
> > matters very much.
> I'd've thought mtime changes more frequently since that's altered when data is
> written.  ctime is changed when attributes are changed.

IIUC, updating mtime for a write is also an attribute change, and that
affects ctime. According to the stat(2) manpage:

       The field st_ctime is changed by writing or by setting  inode  informa-
       tion (i.e., owner, group, link count, mode, etc.).

> Note that Ext4 appears to have a file creation time field in its inode
> (struct ext4_inode::i_crtime[_extra]).  Can Samba be made to use that?

Is it exposed to userspace in any (standard) way? It would be handy to
have that. While we're wishing...it might also be nice to have a
standard way to get at the i_generation from userspace too.

Jeff Layton <jlayton at samba.org>

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