Re: creation time stamps for ext4 ?

[Theodore Tso <tytso@mit.edu>]

On Thu, Oct 05, 2006 at 09:19:37AM -0600, Andreas Dilger wrote:
> On Oct 05, 2006  15:57 +0200, Bj�rn JACKE wrote:
> > I would like to know if there are any plans to introduce a creation 
> > timestamp in future ext3/4 versions. Having a 4th timestamp saving the 
> > creation time would be very good for projekts like Samba for example. 
> > It would be important that creation time can also be set manually 
> > later on by some system call. Systems like FreeBSD's UFS and Solais' 
> > ZFS already support creation times. Unfortunately Linux doesn't have 
> > such a thing standarized anywhere but it would be geat if it would.
> > 
> > Are there any plans to add this?
> 
> I've given this some thought for adding as part of the nsec timestamp
> patch.  That is more feasable if we move the nsec ctime into the main
> inode to double as the version field.

Shoehorning an extra creation time field into the inode is relatively
easy, but it's also necessary to have system calls to get and set the
creation time.  The stat structure doesn't have room for the creation
time, so that means a new version of the stat structure exported the
kernel, and a new version of the stat structure exported by glibc.

So there are VFS and glibc changes necessary to make this be useful.
But that doesn't prevent us from reserving space in the inode and
starting to fill it in with the creation time, although it may be
quite a while before it will be easily available to user programs like
Samba.

						- Ted
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