From: Christoph Hellwig <hch@lst.de>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, hch@lst.de,
kent.overstreet@gmail.com
Subject: Re: [PATCH 04/17] mm/filemap: Support readpage splitting a page
Date: Tue, 3 Nov 2020 08:31:02 +0100 [thread overview]
Message-ID: <20201103073102.GD8389@lst.de> (raw)
In-Reply-To: <20201102184312.25926-5-willy@infradead.org>
On Mon, Nov 02, 2020 at 06:42:59PM +0000, Matthew Wilcox (Oracle) wrote:
> For page splitting to succeed, the thread asking to split the
> page has to be the only one with a reference to the page. Calling
> wait_on_page_locked() while holding a reference to the page will
> effectively prevent this from happening with sufficient threads waiting
> on the same page. Use put_and_wait_on_page_locked() to sleep without
> holding a reference to the page, then retry the page lookup after the
> page is unlocked.
>
> Since we now get the page lock a little earlier in filemap_update_page(),
> we can eliminate a number of duplicate checks. The original intent
> (commit ebded02788b5 ("avoid unnecessary calls to lock_page when waiting
> for IO to complete during a read")) behind getting the page lock later
> was to avoid re-locking the page after it has been brought uptodate by
> another thread. We still avoid that because we go through the normal
> lookup path again after the winning thread has brought the page uptodate.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2020-11-03 7:31 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-02 18:42 [PATCH 00/17] Refactor generic_file_buffered_read Matthew Wilcox (Oracle)
2020-11-02 18:42 ` [PATCH 01/17] mm/filemap: Rename generic_file_buffered_read subfunctions Matthew Wilcox (Oracle)
2020-11-02 18:53 ` Kent Overstreet
2020-11-03 7:27 ` Christoph Hellwig
2020-11-03 14:52 ` Matthew Wilcox
2020-11-03 15:02 ` Amy Parker
2020-11-02 18:42 ` [PATCH 02/17] mm/filemap: Use THPs in generic_file_buffered_read Matthew Wilcox (Oracle)
2020-11-02 18:55 ` Kent Overstreet
2020-11-03 7:28 ` Christoph Hellwig
2020-11-02 18:42 ` [PATCH 03/17] mm/filemap: Pass a sleep state to put_and_wait_on_page_locked Matthew Wilcox (Oracle)
2020-11-02 18:56 ` Kent Overstreet
2020-11-03 7:28 ` Christoph Hellwig
2020-11-02 18:42 ` [PATCH 04/17] mm/filemap: Support readpage splitting a page Matthew Wilcox (Oracle)
2020-11-02 19:00 ` Kent Overstreet
2020-11-02 19:03 ` Matthew Wilcox
2020-11-02 19:12 ` Kent Overstreet
2020-11-03 7:31 ` Christoph Hellwig [this message]
2020-11-02 18:43 ` [PATCH 05/17] mm/filemap: Inline __wait_on_page_locked_async into caller Matthew Wilcox (Oracle)
2020-11-02 19:00 ` Kent Overstreet
2020-11-03 7:31 ` Christoph Hellwig
2020-11-02 18:43 ` [PATCH 06/17] mm/filemap: Don't call ->readpage if IOCB_WAITQ is set Matthew Wilcox (Oracle)
2020-11-02 19:17 ` Kent Overstreet
2020-11-03 7:31 ` Christoph Hellwig
2020-11-05 7:22 ` Nikolay Borisov
2020-11-02 18:43 ` [PATCH 07/17] mm/filemap: Change filemap_read_page calling conventions Matthew Wilcox (Oracle)
2020-11-02 19:37 ` Kent Overstreet
2020-11-03 7:34 ` Christoph Hellwig
2020-11-03 15:11 ` Matthew Wilcox
2020-11-02 18:43 ` [PATCH 08/17] mm/filemap: Change filemap_create_page arguments Matthew Wilcox (Oracle)
2020-11-02 19:38 ` Kent Overstreet
2020-11-03 7:35 ` Christoph Hellwig
2020-11-02 18:43 ` [PATCH 09/17] mm/filemap: Convert filemap_update_page to return an errno Matthew Wilcox (Oracle)
2020-11-02 19:39 ` Kent Overstreet
2020-11-03 7:36 ` Christoph Hellwig
2020-11-02 18:43 ` [PATCH 10/17] mm/filemap: Move the iocb checks into filemap_update_page Matthew Wilcox (Oracle)
2020-11-02 19:45 ` Kent Overstreet
2020-11-03 7:41 ` Christoph Hellwig
2020-11-02 18:43 ` [PATCH 11/17] mm/filemap: Add filemap_range_uptodate Matthew Wilcox (Oracle)
2020-11-02 19:50 ` Kent Overstreet
2020-11-02 20:09 ` Matthew Wilcox
2020-11-03 7:49 ` Christoph Hellwig
2020-11-03 15:18 ` Matthew Wilcox
2020-11-03 15:31 ` Christoph Hellwig
2020-11-03 15:42 ` Matthew Wilcox
2020-11-02 18:43 ` [PATCH 12/17] mm/filemap: Split filemap_readahead out of filemap_get_pages Matthew Wilcox (Oracle)
2020-11-02 19:52 ` Kent Overstreet
2020-11-02 18:43 ` [PATCH 13/17] mm/filemap: Remove parameters from filemap_update_page() Matthew Wilcox (Oracle)
2020-11-02 19:52 ` Kent Overstreet
2020-11-03 7:50 ` Christoph Hellwig
2020-11-02 18:43 ` [PATCH 14/17] mm/filemap: Restructure filemap_get_pages Matthew Wilcox (Oracle)
2020-11-02 20:05 ` Kent Overstreet
2020-11-03 7:57 ` Christoph Hellwig
2020-11-03 14:46 ` Matthew Wilcox
2020-11-03 15:29 ` Christoph Hellwig
2020-11-02 18:43 ` [PATCH 15/17] mm/filemap: Don't relock the page after calling readpage Matthew Wilcox (Oracle)
2020-11-02 20:06 ` Kent Overstreet
2020-11-03 8:00 ` Christoph Hellwig
2020-11-03 15:24 ` Matthew Wilcox
2020-11-03 17:13 ` Christoph Hellwig
2020-11-03 18:55 ` Matthew Wilcox
2020-11-02 18:43 ` [PATCH 16/17] mm/filemap: rename generic_file_buffered_read to filemap_read Matthew Wilcox (Oracle)
2020-11-02 20:06 ` Kent Overstreet
2020-11-02 18:43 ` [PATCH 17/17] mm: simplify generic_file_read_iter Matthew Wilcox (Oracle)
2020-11-02 20:07 ` Kent Overstreet
2020-11-02 20:14 ` [PATCH 00/17] Refactor generic_file_buffered_read Kent Overstreet
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