Date: Wed, 16 Jun 2010 19:04:46 +0200
From: Andrea Arcangeli <aarcange@redhat.com>
To: Rik van Riel <riel@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>, Christoph Hellwig <hch@infradead.org>,
       Mel Gorman <mel@csn.ul.ie>, linux-kernel@vger.kernel.org,
       linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
       Dave Chinner <david@fromorbit.com>,
       Chris Mason <chris.mason@oracle.com>
Subject: Re: [RFC PATCH 0/6] Do not call ->writepage[s] from direct reclaim
 and use a_ops->writepages() where possible
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 <4C17AF2D.2060904@redhat.com>
 <20100615165423.GA16868@infradead.org>
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On Wed, Jun 16, 2010 at 12:59:54PM -0400, Rik van Riel wrote:
> __GFP_IO can wait for filesystem activity

Hmm I think it's for submitting I/O, not about waiting. At some point
you may not enter the FS because of the FS locks you already hold
(like within writepage itself), but you can still submit I/O through
blkdev layer.

> __GFP_FS can kick off new filesystem activity

Yes that's for dcache/icache/writepage or anything that can reenter
the fs locks and deadlock IIRC.
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