From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>, xfs@oss.sgi.com
Subject: Re: xattr atomicy
Date: Mon, 16 Dec 2013 07:19:00 -0800 [thread overview]
Message-ID: <20131216151900.GA12360@infradead.org> (raw)
In-Reply-To: <20131213215117.GV10988@dastard>
On Sat, Dec 14, 2013 at 08:51:17AM +1100, Dave Chinner wrote:
> Yes, but they are still atomic from a user and crash recovery
> point of view....
I can't see how we can guarantee an atomic update for them, both
in the case of an I/O error and an actual system crash.
> Well, I think it's a bit different to the directory block case - the
> directory blocks are filesystem metadata, while xattrs contain user
> data. Hence if we log user xattrs a user can consume all of the log
> bandwidth writing xattrs and degrade the metadata modification
> performance of the rest of the filesystem.
We're getting close to do that with namespace modifications with
all your scalability work :)
I think that's a point to consider, but not really black and white. It
just makes it a bit easier to consume log bandwith, and increases the
need to have some form of per-user quotas for this sort of operations.
> So, IMO, the first question we need to answer is whether the current
> behaviour is actually a problem for anyone....
I've not heard of real life problems, but an interfaces that has very
nice behavior for the common case, but a much less optimal for a corner
cases is bound to cause trouble.
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prev parent reply other threads:[~2013-12-16 15:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-13 11:56 xattr atomicy Christoph Hellwig
2013-12-13 19:52 ` Ben Myers
2013-12-13 21:51 ` Dave Chinner
2013-12-16 15:19 ` Christoph Hellwig [this message]
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