Re: [PATCH 02/18] xstat: Add a pair of system calls to make extended file stats available [ver #6]

From: John Stoffel
Date: Thu Jul 22 2010 - 15:20:05 EST


>>>>> "Jeremy" == Jeremy Allison <jra@xxxxxxxxx> writes:

Jeremy> On Thu, Jul 22, 2010 at 12:58:50PM -0400, Trond Myklebust wrote:
>>
>> That would make it impossible to export the filesystem with NFSv2 and
>> v3. They do rely on ctime checking for certain operations (e.g. deciding
>> when to invalidate access and acl caches). NFSv4 needs this too if the
>> filesystem has no dedicated change attribute.
>>
>> Still, I suppose the market for exporting the same filesystem with both
>> NFS and Samba is limited...

Jeremy> Ask NetApp about that :-). They have built a rather large
Jeremy> business on just that fact :-).

And it does work, as long as you also go with either unix or windows
semantics for the security and permissions bits. If you try to use
the mixed-mode, you're in for a world of hurt.

Oh yeah, Netapp still uses dump/restore for it's backups. :] Though
whether it's still dependent on the optimization of ctime being used
to know whether to just dump the inode only or not, I can't say.

John
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