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Re: [PATCH 18/18] xfs: recall pNFS layouts on conflicting access

To: Christoph Hellwig <hch@xxxxxx>
Subject: Re: [PATCH 18/18] xfs: recall pNFS layouts on conflicting access
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 7 Jan 2015 10:18:46 +1100
Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>, Jeff Layton <jlayton@xxxxxxxxxxxxxxx>, linux-nfs@xxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1420561721-9150-19-git-send-email-hch@xxxxxx>
References: <1420561721-9150-1-git-send-email-hch@xxxxxx> <1420561721-9150-19-git-send-email-hch@xxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Tue, Jan 06, 2015 at 05:28:41PM +0100, Christoph Hellwig wrote:
> Recall all outstanding pNFS layouts and truncates, writes and similar extent
> list modifying operations.

This is not sufficient to isolate extent manipulations. mmap writes
can trigger allocation through ->page_mkwrite, and can also trigger
extent conversion at IO completion without first needing allocation.

Maybe I'm missing something - this patchset needs some comments
documenting the locking used in XFS to co-ordinate layout coherency
at the client side with IO that is in progress for clients with
overlapping block maps, as well as against server side application


Dave Chinner

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