From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 6/8] xfs: don't chain ioends during writepage submission
Date: Thu, 11 Feb 2016 17:39:10 +1100 [thread overview]
Message-ID: <20160211063910.GF19486@dastard> (raw)
In-Reply-To: <20160210113609.GC15221@infradead.org>
On Wed, Feb 10, 2016 at 03:36:09AM -0800, Christoph Hellwig wrote:
> > + LIST_HEAD(submit_list);
> > + struct xfs_ioend *ioend, *next;
> > struct buffer_head *bh, *head;
> > ssize_t len = 1 << inode->i_blkbits;
> > int error = 0;
> > int uptodate = 1;
> > int count = 0;
>
> The count variable is pointless now - we only check for it being
> non-zero, and we can do the same with a list_emptry on submit_list.
Actually, it's not pointless - we need it to determine what to
with the page. We have to start writeback on the page if there were
no errors, but the number of buffers we added to the ioend
determines if we need to end page writeback immediately (i.e. no
buffers added). This is spearate to whether we allocated a new ioend
on the page and hence have an ioend to submit on the submit_list.
That said, looking at this did point out a bug in this
version of the patch - if no buffers were added to the ioends, then
we didn't clear the dirty bit on the page and transition through the
writeback state, as the original code was doing. I did trip over
this in a test run, so it's a real problem that needed to be fixed.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2016-02-11 6:39 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-10 8:47 [PATCH 0/8 v4] xfs: get rid of xfs_cluster_write Dave Chinner
2016-02-10 8:47 ` [PATCH 1/8] xfs: remove nonblocking mode from xfs_vm_writepage Dave Chinner
2016-02-10 8:47 ` [PATCH 2/8] xfs: remove xfs_cancel_ioend Dave Chinner
2016-02-10 11:28 ` Christoph Hellwig
2016-02-11 0:21 ` Dave Chinner
2016-02-11 15:14 ` Christoph Hellwig
2016-02-11 20:59 ` Dave Chinner
2016-02-10 8:47 ` [PATCH 3/8] xfs: Introduce writeback context for writepages Dave Chinner
2016-02-10 11:31 ` Christoph Hellwig
2016-02-11 0:25 ` Dave Chinner
2016-02-10 8:47 ` [PATCH 4/8] xfs: xfs_cluster_write is redundant Dave Chinner
2016-02-10 8:47 ` [PATCH 5/8] xfs: factor mapping out of xfs_do_writepage Dave Chinner
2016-02-10 8:47 ` [PATCH 6/8] xfs: don't chain ioends during writepage submission Dave Chinner
2016-02-10 11:36 ` Christoph Hellwig
2016-02-11 0:26 ` Dave Chinner
2016-02-11 6:39 ` Dave Chinner [this message]
2016-02-10 8:47 ` [PATCH 7/8] [RFC] xfs: build bios directly in xfs_add_to_ioend Dave Chinner
2016-02-10 8:47 ` [PATCH 8/8] [RFC] xfs: don't release bios on completion immediately Dave Chinner
2016-02-10 9:05 ` [PATCH 0/8 v4] xfs: get rid of xfs_cluster_write Christoph Hellwig
2016-02-10 18:25 ` Christoph Hellwig
2016-02-10 21:25 ` Dave Chinner
2016-02-11 15:13 ` Christoph Hellwig
2016-02-11 20:12 ` Dave Chinner
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