From: Christoph Hellwig <hch@lst.de>
To: Brian Foster <bfoster@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 21/22] xfs: add support for sub-pagesize writeback without buffer_heads
Date: Tue, 10 Jul 2018 14:15:30 +0200 [thread overview]
Message-ID: <20180710121530.GA765@lst.de> (raw)
In-Reply-To: <20180710010202.GA5835@killians.ges.redhat.com>
On Mon, Jul 09, 2018 at 09:02:02PM -0400, Brian Foster wrote:
> It looks to me that if the page itself isn't uptodate, we
> overwrite a block of that page and then the writepage fails, clearing
> the buffer uptodate status means that the next read would return what is
> on disk (not what was just written to the page).
With iomap we never clear the uptodate bit, and we only set it when
the part of the page contains valid data. With buffer heads we might
indeed clear the uptodate bit after a write error. Now if the whole
page is set uptodate we won't re-read it, but if the whole page wasn't
uptodate it seems like the buffer head code will lose data in that
case, which looks wrong to me.
> I'm not sure that's
> what happens if the page was already uptodate before the
> overwrite/writepage, however, I didn't notice anything that cleared page
> uptodate status on a writepage I/O error..?
Yes, the buffer head code seems inconsistent in how it treats the buffer
vs page uptodate bits.
next prev parent reply other threads:[~2018-07-10 12:13 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-02 14:57 stop using buffer heads in xfs v7 Christoph Hellwig
2018-07-02 14:57 ` [PATCH 01/22] xfs: use iomap for blocksize == PAGE_SIZE readpage and readpages Christoph Hellwig
2018-07-02 14:57 ` [PATCH 02/22] xfs: simplify xfs_aops_discard_page Christoph Hellwig
2018-07-02 14:57 ` [PATCH 03/22] xfs: move locking into xfs_bmap_punch_delalloc_range Christoph Hellwig
2018-07-02 14:57 ` [PATCH 04/22] xfs: do not set the page uptodate in xfs_writepage_map Christoph Hellwig
2018-07-02 14:57 ` [PATCH 05/22] xfs: don't clear imap_valid for a non-uptodate buffers Christoph Hellwig
2018-07-02 14:57 ` [PATCH 06/22] xfs: don't use XFS_BMAPI_IGSTATE in xfs_map_blocks Christoph Hellwig
2018-07-02 14:57 ` [PATCH 07/22] xfs: remove xfs_reflink_trim_irec_to_next_cow Christoph Hellwig
2018-07-02 14:57 ` [PATCH 08/22] xfs: remove xfs_map_cow Christoph Hellwig
2018-07-02 14:58 ` [PATCH 09/22] xfs: rename the offset variable in xfs_writepage_map Christoph Hellwig
2018-07-02 14:58 ` [PATCH 10/22] xfs: make xfs_writepage_map extent map centric Christoph Hellwig
2018-07-02 14:58 ` [PATCH 11/22] xfs: remove the now unused XFS_BMAPI_IGSTATE flag Christoph Hellwig
2018-07-02 14:58 ` [PATCH 12/22] xfs: remove xfs_reflink_find_cow_mapping Christoph Hellwig
2018-07-02 14:58 ` [PATCH 13/22] xfs: simplify xfs_map_blocks by using xfs_iext_lookup_extent directly Christoph Hellwig
2018-07-02 14:58 ` [PATCH 14/22] xfs: remove the imap_valid flag Christoph Hellwig
2018-07-02 14:58 ` [PATCH 15/22] xfs: don't look at buffer heads in xfs_add_to_ioend Christoph Hellwig
2018-07-02 14:58 ` [PATCH 16/22] xfs: move all writeback buffer_head manipulation into xfs_map_at_offset Christoph Hellwig
2018-07-02 14:58 ` [PATCH 17/22] xfs: remove xfs_start_page_writeback Christoph Hellwig
2018-07-02 14:58 ` [PATCH 18/22] xfs: refactor the tail of xfs_writepage_map Christoph Hellwig
2018-07-02 14:58 ` [PATCH 19/22] xfs: allow writeback on pages without buffer heads Christoph Hellwig
2018-07-02 14:58 ` [PATCH 20/22] iomap: add support for sub-pagesize buffered I/O " Christoph Hellwig
2018-07-03 12:31 ` Brian Foster
2018-07-03 21:52 ` Darrick J. Wong
2018-07-02 14:58 ` [PATCH 21/22] xfs: add support for sub-pagesize writeback without buffer_heads Christoph Hellwig
2018-07-03 12:36 ` Brian Foster
2018-07-03 22:05 ` Darrick J. Wong
2018-07-08 15:16 ` Christoph Hellwig
2018-07-10 1:02 ` Brian Foster
2018-07-10 12:15 ` Christoph Hellwig [this message]
2018-07-11 10:58 ` Brian Foster
2018-07-02 14:58 ` [PATCH 22/22] xfs: update my copyrights for the writeback and iomap code Christoph Hellwig
2018-07-03 12:36 ` Brian Foster
2018-07-03 21:51 ` Darrick J. Wong
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