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From: Brian Foster <bfoster@redhat.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 05/14] iomap: Support THPs in invalidatepage
Date: Wed, 14 Oct 2020 16:00:19 -0400
Message-ID: <20201014200019.GA1119840@bfoster> (raw)
In-Reply-To: <20201014172634.GP20115@casper.infradead.org>

On Wed, Oct 14, 2020 at 06:26:34PM +0100, Matthew Wilcox wrote:
> On Wed, Oct 14, 2020 at 09:33:47AM -0700, Darrick J. Wong wrote:
> > > @@ -1415,7 +1420,6 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> > >  			 */
> > >  			if (wpc->ops->discard_page)
> > >  				wpc->ops->discard_page(page);
> > > -			ClearPageUptodate(page);
> > 
> > Er, I don't get it -- why do we now leave the page up to date after
> > writeback fails?
> 
> The page is still uptodate -- every byte in this page is at least as new
> as the corresponding bytes on disk.
> 

That seems rather odd if the preceding ->discard_page() turned an
underlying delalloc block into a hole. Technically the original written
data is still in the page, but it's no longer allocated/mapped or dirty
so really no longer in sync with on-disk state. Hm?

Brian


  reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-14  3:03 [PATCH 00/14] Transparent Huge Page support for XFS Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 01/14] fs: Support THPs in vfs_dedupe_file_range Matthew Wilcox (Oracle)
2020-10-14 16:12   ` Darrick J. Wong
2020-10-14 17:16     ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 02/14] fs: Make page_mkwrite_check_truncate thp-aware Matthew Wilcox (Oracle)
2020-10-14 16:17   ` Darrick J. Wong
2020-10-14 17:23     ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 03/14] iomap: Support THPs in BIO completion path Matthew Wilcox (Oracle)
2020-10-15  9:50   ` Christoph Hellwig
2020-10-14  3:03 ` [PATCH 04/14] iomap: Support THPs in iomap_adjust_read_range Matthew Wilcox (Oracle)
2020-10-15  9:50   ` Christoph Hellwig
2020-10-14  3:03 ` [PATCH 05/14] iomap: Support THPs in invalidatepage Matthew Wilcox (Oracle)
2020-10-14 16:33   ` Darrick J. Wong
2020-10-14 17:26     ` Matthew Wilcox
2020-10-14 20:00       ` Brian Foster [this message]
2020-10-14  3:03 ` [PATCH 06/14] iomap: Support THPs in iomap_is_partially_uptodate Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 07/14] iomap: Support THPs in readpage Matthew Wilcox (Oracle)
2020-10-14 16:39   ` Darrick J. Wong
2020-10-14 17:35     ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 08/14] iomap: Support THPs in readahead Matthew Wilcox (Oracle)
2020-10-15  9:52   ` Christoph Hellwig
2020-10-14  3:03 ` [PATCH 09/14] iomap: Change iomap_write_begin calling convention Matthew Wilcox (Oracle)
2020-10-14 16:47   ` Darrick J. Wong
2020-10-14 17:41     ` Matthew Wilcox
2020-10-14 18:08       ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 10/14] iomap: Handle THPs when writing to pages Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 11/14] iomap: Support THP writeback Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 12/14] iomap: Inline data shouldn't see THPs Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 13/14] iomap: Handle tail pages in iomap_page_mkwrite Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 14/14] xfs: Support THPs Matthew Wilcox (Oracle)
2020-10-14 16:51   ` Darrick J. Wong
2020-10-14 17:30     ` Matthew Wilcox

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