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Date: Wed, 20 Jun 2012 16:41:33 +1000
From: Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH v2] xfs: Fix overallocation in xfs_buf_allocate_memory()
Message-ID: <20120620064133.GF30705@dastard>
References: <1338935546-3914-1-git-send-email-jack@suse.cz>
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To: Jan Kara <jack@suse.cz>
Cc: Ben Myers <bpm@sgi.com>, Alex Elder <elder@kernel.org>, David Chinner <dchinner@redhat.com>, xfs@oss.sgi.com

On Wed, Jun 06, 2012 at 12:32:26AM +0200, Jan Kara wrote:
> Commit de1cbee which removed b_file_offset in favor of b_bn introduced a bug
> causing xfs_buf_allocate_memory() to overestimate the number of necessary
> pages. The problem is that xfs_buf_alloc() sets b_bn to -1 and thus effectively
> every buffer is straddling a page boundary which causes
> xfs_buf_allocate_memory() to allocate two pages and use vmalloc() for access
> which is unnecessary.
> 
> Dave says xfs_buf_alloc() doesn't need to set b_bn to -1 anymore since the
> buffer is inserted into the cache only after being fully initialized now.
> So just make xfs_buf_alloc() fill in proper block number from the beginning.
> 
> CC: David Chinner <dchinner@redhat.com>
> Signed-off-by: Jan Kara <jack@suse.cz>

Hmmm, the

Reviewed-by: Dave Chinner <dchinner@redhat.com>

I sent yesterday doesn't appear to have made it to the list. Oh
well, try again...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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