From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, "Theodore Ts'o" <tytso@mit.edu>,
linux-kernel@vger.kernel.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
xfs@oss.sgi.com
Subject: Re: [PATCH 3/4] writeback: pay attention to wbc->nr_to_write in write_cache_pages
Date: Thu, 29 Apr 2010 14:39:31 -0700 [thread overview]
Message-ID: <20100429143931.331c2bab.akpm@linux-foundation.org> (raw)
In-Reply-To: <1271731314-5893-4-git-send-email-david@fromorbit.com>
On Tue, 20 Apr 2010 12:41:53 +1000
Dave Chinner <david@fromorbit.com> wrote:
> If a filesystem writes more than one page in ->writepage, write_cache_pages
> fails to notice this and continues to attempt writeback when wbc->nr_to_write
> has gone negative - this trace was captured from XFS:
>
>
> wbc_writeback_start: towrt=1024
> wbc_writepage: towrt=1024
> wbc_writepage: towrt=0
> wbc_writepage: towrt=-1
> wbc_writepage: towrt=-5
> wbc_writepage: towrt=-21
> wbc_writepage: towrt=-85
>
Bug.
AFAIT it's a regression introduced by
: commit 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4
: Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
: AuthorDate: Thu Oct 16 10:09:17 2008 -0400
: Commit: Theodore Ts'o <tytso@mit.edu>
: CommitDate: Thu Oct 16 10:09:17 2008 -0400
:
: vfs: Add no_nrwrite_index_update writeback control flag
I suggest that what you do here is remove the local `nr_to_write' from
write_cache_pages() and go back to directly using wbc->nr_to_write
within the loop.
And thus we restore the convention that if the fs writes back more than
a single page, it subtracts (nr_written - 1) from wbc->nr_to_write.
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next prev parent reply other threads:[~2010-04-29 21:39 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-20 2:41 [PATCH 0/4] writeback: tracing and wbc->nr_to_write fixes Dave Chinner
2010-04-20 2:41 ` [PATCH 1/4] writeback: initial tracing support Dave Chinner
2010-05-21 15:06 ` Christoph Hellwig
2010-04-20 2:41 ` [PATCH 2/4] writeback: Add tracing to balance_dirty_pages Dave Chinner
2010-04-20 2:41 ` [PATCH 3/4] writeback: pay attention to wbc->nr_to_write in write_cache_pages Dave Chinner
2010-04-22 19:07 ` Jan Kara
2010-04-25 3:33 ` tytso
2010-04-26 1:49 ` Dave Chinner
2010-04-26 2:43 ` tytso
2010-04-26 2:45 ` tytso
2010-04-27 3:30 ` Dave Chinner
2010-04-29 21:39 ` Andrew Morton [this message]
2010-04-30 6:01 ` Aneesh Kumar K. V
2010-04-30 19:43 ` Andrew Morton
2010-05-01 19:47 ` tytso
2010-04-20 2:41 ` [PATCH 4/4] xfs: remove nr_to_write writeback windup Dave Chinner
2010-04-22 19:09 ` Jan Kara
2010-04-26 0:46 ` Dave Chinner
2010-04-20 3:40 ` [PATCH 5/4] writeback: limit write_cache_pages integrity scanning to current EOF Dave Chinner
2010-04-20 23:28 ` Jamie Lokier
2010-04-20 23:31 ` Dave Chinner
2010-04-22 19:13 ` Jan Kara
2010-04-20 12:02 ` [PATCH 0/4] writeback: tracing and wbc->nr_to_write fixes Richard Kennedy
2010-04-20 23:29 ` Dave Chinner
2010-05-21 15:05 ` Christoph Hellwig
2010-05-22 0:09 ` Dave Chinner
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