1From: Jeff Layton <jlayton@samba.org>
2Subject: Re: [RFC][PATCH 06/10] cifs: define inode-level cache object and
3	register them
4Date: Fri, 25 Jun 2010 18:26:51 -0400
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15Cc: linux-cifs@vger.kernel.org, samba-technical@lists.samba.org,
16	linux-kernel@vger.kernel.org, Steve French <smfrench@gmail.com>,
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18To: David Howells <dhowells@redhat.com>
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72Archived-At: <http://permalink.gmane.org/gmane.linux.kernel/1003148>
73
74On Fri, 25 Jun 2010 22:46:38 +0100
75David Howells <dhowells@redhat.com> wrote:
76
77> Jeff Layton <jlayton@samba.org> wrote:
78>
79> > Looks like it mostly uses the ctime. IMO, the mtime would be a better
80> > choice since it changes less frequently, but I don't guess that it
81> > matters very much.
82>
83> I'd've thought mtime changes more frequently since that's altered when data is
84> written.  ctime is changed when attributes are changed.
85>
86
87IIUC, updating mtime for a write is also an attribute change, and that
88affects ctime. According to the stat(2) manpage:
89
90       The field st_ctime is changed by writing or by setting  inode  informa-
91       tion (i.e., owner, group, link count, mode, etc.).
92
93> Note that Ext4 appears to have a file creation time field in its inode
94> (struct ext4_inode::i_crtime[_extra]).  Can Samba be made to use that?
95>
96
97Is it exposed to userspace in any (standard) way? It would be handy to
98have that. While we're wishing...it might also be nice to have a
99standard way to get at the i_generation from userspace too.
100
101--
102Jeff Layton <jlayton@samba.org>
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106