Re: ext4 developers interlock meeting minutes (June 28th, 2006)

On Jun 30, 2006  16:39 -0700, Mingming Cao wrote:
> 3. finer timestamp patch was discussed a bit, is it ready to include to
> the series? Stephen commented to wait until the kernel patch is settle
> down and the corresponding e2fsprogs changes are there. Right now he has
> concerns about the kernel patches. To be discussed with Andreas.

Unfortunately, I wasn't able to attend last week.  What was the general
outcome of this discussion?  Is the on-disk structure of the nsec and
epoch timestamp extensions acceptable?

Is there consensus about the use (and value!) of the superblock ROCOMPAT
flag?  That was added at the request of Stephen, to handle the rare case
where the client is updating the mtime/ctime of the inode, but might not
be able to store this on disk, and cause confusion for make, etc.

The ability to mark a filesystem ROCOMPAT_NS_TIMESTAMP by e2fsck and
handle the required EA shifting isn't something that CFS needs, and
isn't really needed except for rare cases.  This could be added to new
filesystems at mke2fs time if desired, though it does impose additional
interoperability restrictions that may not be needed.


There was some question from Andreas Gruenbacher (SuSE) on whether we
should be storing nsec resolution timestamps for the atime at all.

What is still missing from the patch is the ability to "add" extended
timestamps to existing large inodes that may already have EA data (i.e.
if ROCOMPAT_NS_TIMESTAMP isn't set).  This is something that will be
needed by CFS at some point, but isn't needed for initial use like having
a firm consensus of the on-disk format.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.


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