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From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Yang Shi <yang.shi@linux.alibaba.com>,
	Dave Chinner <dchinner@redhat.com>,
	linux-kernel@vger.kernel.org,
	William Kucharski <william.kucharski@oracle.com>
Subject: Re: [PATCH v3 04/12] mm/filemap: Add mapping_seek_hole_data
Date: Tue, 27 Oct 2020 20:04:58 +0000
Message-ID: <20201027200458.GX20115@casper.infradead.org> (raw)
In-Reply-To: <20201027185809.GB15201@infradead.org>

On Tue, Oct 27, 2020 at 06:58:09PM +0000, Christoph Hellwig wrote:
> > +/**
> > + * mapping_seek_hole_data - Seek for SEEK_DATA / SEEK_HOLE in the page cache.
> > + * @mapping: Address space to search.
> > + * @start: First byte to consider.
> > + * @end: Limit of search (exclusive).
> > + * @whence: Either SEEK_HOLE or SEEK_DATA.
> > + *
> > + * If the page cache knows which blocks contain holes and which blocks
> > + * contain data, your filesystem can use this function to implement
> > + * SEEK_HOLE and SEEK_DATA.  This is useful for filesystems which are
> > + * entirely memory-based such as tmpfs, and filesystems which support
> > + * unwritten extents.
> > + *
> > + * Return: The requested offset on successs, or -ENXIO if @whence specifies
> > + * SEEK_DATA and there is no data after @start.  There is an implicit hole
> > + * after @end - 1, so SEEK_HOLE returns @end if all the bytes between @start
> > + * and @end contain data.
> > + */
> 
> This seems to just lift the tmpfs one to common code.  If it really
> is supposed to be generic it should be able to replace
> page_cache_seek_hole_data as well.  So I don't think moving this without
> removing the other common one is an all that good idea.

I have that patch here:

http://git.infradead.org/users/willy/pagecache.git/commitdiff/a4e435b5ed14a0b898da6e5a66fe232f467b8ba1

I was going to let this patch go upstream through Andrew's tree, then
submit that one through Darrick's tree.  But I can add that patch to
the next submission of this series if you'd rather.

  reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-26  4:13 [PATCH v3 00/12] Overhaul multi-page lookups for THP Matthew Wilcox (Oracle)
2020-10-26  4:13 ` [PATCH v3 01/12] mm: Make pagecache tagged lookups return only head pages Matthew Wilcox (Oracle)
2020-10-28  7:50   ` Mike Rapoport
2020-11-12 17:41     ` Matthew Wilcox
2020-11-12 19:11       ` Mike Rapoport
2020-10-26  4:13 ` [PATCH v3 02/12] mm/shmem: Use pagevec_lookup in shmem_unlock_mapping Matthew Wilcox (Oracle)
2020-10-26  4:13 ` [PATCH v3 03/12] mm/filemap: Add helper for finding pages Matthew Wilcox (Oracle)
2020-10-27 18:56   ` Christoph Hellwig
2020-11-12 14:25     ` Matthew Wilcox
2020-10-26  4:14 ` [PATCH v3 04/12] mm/filemap: Add mapping_seek_hole_data Matthew Wilcox (Oracle)
2020-10-26 10:48   ` Jan Kara
2020-10-26 12:17     ` Matthew Wilcox
2020-10-26 14:49       ` Jan Kara
2020-10-27 18:58   ` Christoph Hellwig
2020-10-27 20:04     ` Matthew Wilcox [this message]
2020-10-28  6:40       ` Christoph Hellwig
2020-10-26  4:14 ` [PATCH v3 05/12] mm: Add and use find_lock_entries Matthew Wilcox (Oracle)
2020-10-26  4:14 ` [PATCH v3 06/12] mm: Add an 'end' parameter to find_get_entries Matthew Wilcox (Oracle)
2020-10-26  4:14 ` [PATCH v3 07/12] mm: Add an 'end' parameter to pagevec_lookup_entries Matthew Wilcox (Oracle)
2020-10-26  4:14 ` [PATCH v3 08/12] mm: Remove nr_entries parameter from pagevec_lookup_entries Matthew Wilcox (Oracle)
2020-10-26  4:14 ` [PATCH v3 09/12] mm: Pass pvec directly to find_get_entries Matthew Wilcox (Oracle)
2020-10-26  4:14 ` [PATCH v3 10/12] mm: Remove pagevec_lookup_entries Matthew Wilcox (Oracle)
2020-10-26  4:14 ` [PATCH v3 11/12] mm/truncate,shmem: Handle truncates that split THPs Matthew Wilcox (Oracle)
2020-10-26 11:05   ` Jan Kara
2020-10-26  4:14 ` [PATCH v3 12/12] mm/filemap: Return only head pages from find_get_entries Matthew Wilcox (Oracle)

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