From: Mark Tinguely <tinguely@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 04/18] xfs: page type check in writeback only checks last buffer
Date: Mon, 16 Apr 2012 11:15:29 -0500 [thread overview]
Message-ID: <4F8C45A1.1090200@sgi.com> (raw)
In-Reply-To: <1334319061-12968-5-git-send-email-david@fromorbit.com>
On 04/13/12 07:10, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> xfs_is_delayed_page() checks to see if a page has buffers matching
> the given IO type passed in. It does so by walking the buffer heads
> on the page and checking if the state flags match the IO type.
>
> However, the "acceptable" variable that is calculated is overwritten
> every time a new buffer is checked. Hence if the first buffer on the
> page is of the right type, this state is lost if the second buffer
> is not of the correct type. This means that xfs_aops_discard_page()
> may not discard delalloc regions when it is supposed to, and
> xfs_convert_page() may not cluster IO as efficiently as possible.
>
> This problem only occurs on filesystems with a block size smaller
> than page size.
>
> Also, rename xfs_is_delayed_page() to xfs_check_page_type() to
> better describe what it is doing - it is not delalloc specific
> anymore.
>
> The problem was first noticed by Peter Watkins.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---
> fs/xfs/xfs_aops.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 0783def..2fc12db 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -623,7 +623,7 @@ xfs_map_at_offset(
> * or delayed allocate extent.
> */
> STATIC int
> -xfs_is_delayed_page(
> +xfs_check_page_type(
> struct page *page,
> unsigned int type)
> {
> @@ -637,11 +637,11 @@ xfs_is_delayed_page(
> bh = head = page_buffers(page);
> do {
> if (buffer_unwritten(bh))
> - acceptable = (type == IO_UNWRITTEN);
> + acceptable += (type == IO_UNWRITTEN);
> else if (buffer_delay(bh))
> - acceptable = (type == IO_DELALLOC);
> + acceptable += (type == IO_DELALLOC);
> else if (buffer_dirty(bh)&& buffer_mapped(bh))
> - acceptable = (type == IO_OVERWRITE);
> + acceptable += (type == IO_OVERWRITE);
> else
> break;
Looks good.
Could short-cut and return 1 on the first acceptable buffer rather than
scanning the entire too.
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
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next prev parent reply other threads:[~2012-04-16 16:15 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-13 12:10 [PATCH 0/18] xfs: current patch queue Dave Chinner
2012-04-13 12:10 ` [PATCH 01/18] xfs: Ensure inode reclaim can run during quotacheck Dave Chinner
2012-04-13 18:01 ` Mark Tinguely
2012-04-29 21:37 ` Christoph Hellwig
2012-04-13 12:10 ` [PATCH 02/18] xfs: pass shutdown method into xfs_trans_ail_delete_bulk Dave Chinner
2012-04-13 17:40 ` Mark Tinguely
2012-04-13 23:04 ` Dave Chinner
2012-04-13 23:38 ` [PATCH 02/18 V2] " Dave Chinner
2012-04-16 18:49 ` Mark Tinguely
2012-04-13 12:10 ` [PATCH 03/18] xfs: Do background CIL flushes via a workqueue Dave Chinner
2012-04-17 17:54 ` Mark Tinguely
2012-04-17 21:21 ` Ben Myers
2012-04-17 21:49 ` Ben Myers
2012-04-18 1:47 ` Dave Chinner
2012-04-30 1:24 ` Dave Chinner
2012-04-30 6:09 ` Dave Chinner
2012-04-18 1:58 ` Dave Chinner
2012-04-13 12:10 ` [PATCH 04/18] xfs: page type check in writeback only checks last buffer Dave Chinner
2012-04-16 16:15 ` Mark Tinguely [this message]
2012-04-29 21:39 ` Christoph Hellwig
2012-04-30 0:29 ` Dave Chinner
2012-04-13 12:10 ` [PATCH 05/18] xfs: Use preallocation for inodes with extsz hints Dave Chinner
2012-04-13 16:45 ` Mark Tinguely
2012-04-16 15:59 ` Mark Tinguely
2012-04-13 12:10 ` [PATCH 06/18] xfs: fix buffer lookup race on allocation failure Dave Chinner
2012-04-13 18:32 ` Mark Tinguely
2012-04-13 12:10 ` [PATCH 07/18] xfs: check for buffer errors before waiting Dave Chinner
2012-04-13 17:56 ` Mark Tinguely
2012-04-13 12:10 ` [PATCH 08/18] xfs: fix incorrect b_offset initialisation Dave Chinner
2012-04-13 12:10 ` [PATCH 09/18] xfs: use kmem_zone_zalloc for buffers Dave Chinner
2012-04-13 12:10 ` [PATCH 10/18] xfs: clean up buffer get/read call API Dave Chinner
2012-04-13 12:10 ` [PATCH 11/18] xfs: kill b_file_offset Dave Chinner
2012-04-13 12:10 ` [PATCH 12/18] xfs: use blocks for counting length of buffers Dave Chinner
2012-04-13 12:10 ` [PATCH 13/18] xfs: use blocks for storing the desired IO size Dave Chinner
2012-04-13 12:10 ` [PATCH 14/18] xfs: kill xfs_buf_btoc Dave Chinner
2012-04-13 12:10 ` [PATCH 15/18] xfs: kill XBF_LOCK Dave Chinner
2012-04-13 21:20 ` Mark Tinguely
2012-04-13 12:10 ` [PATCH 16/18] xfs: kill xfs_read_buf() Dave Chinner
2012-04-13 12:11 ` [PATCH 17/18] xfs: kill XBF_DONTBLOCK Dave Chinner
2012-04-16 14:34 ` Mark Tinguely
2012-04-13 12:11 ` [PATCH 18/18] xfs: use iolock on XFS_IOC_ALLOCSP calls Dave Chinner
2012-04-16 15:10 ` Mark Tinguely
2012-04-16 21:29 ` [PATCH 0/18] xfs: current patch queue Ben Myers
2012-04-17 4:12 ` Dave Chinner
2012-04-17 14:44 ` Ben Myers
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