On Thu, Jul 29, 2010 at 09:04:01AM +1000, Neil Brown wrote:

On Wed, 28 Jul 2010 18:28:02 +0100
David Howells [off-list ref] wrote:

quoted

Neil Brown [off-list ref] wrote:

quoted

ctime and mtime have real cache-coherence semantics which require them being
updated by the kernel (whether the cache is on an NFS client, in a backup
archive, or in a .o translation of a .c file).

So does creation time, at least for CIFS caching.  Creation time has potential
for spotting when the object at a pathname has changed for something else,
given the lack of inode number and inode generation from windows servers.
Creation time gives us one more datum to use.

This justifies for me why a CIFS client would want to extract the
creation-time from the CIFS protocol, but not why you want to expose it via a
generic interface.
The kernel/filesystem doesn't need to maintain creation-time to meet this
need, only the CIFS server needs to maintain it

For what it's worth, the NFSv4 server would also export creation time if
we had it.

--b.