Re: PATCH reduce impact of FIFREEZE on userland processes

From: Christoph Hellwig
Date: Sat Dec 08 2012 - 07:11:59 EST


On Fri, Dec 07, 2012 at 11:42:55AM +1100, Dave Chinner wrote:
> The problem wth doing this is that the sync can delay the freeze
> process by quite some time under the exact conditions you describe.
> If you want freeze to take effect immediately (i.e instantly stop
> new modifications), then adding a sync will break this semantic.
> THere are existing users of freeze that require this behaviour...

But that's only because he uses the big hammer sync_filesystem() which
actually waits for I/O completion. I agree that this is a bad idea,
but if we'd just do a writeback_inodes_sb() call in this place that
starts asynchronous writeout I think everyone would benefit.

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