From: Matthew Wilcox <willy@infradead.org> To: Christoph Hellwig <hch@infradead.org> Cc: David Howells <dhowells@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>, Steve French <sfrench@samba.org>, Shyam Prasad N <nspmangalore@gmail.com>, Rohith Surabattula <rohiths.msft@gmail.com>, Dave Wysochanski <dwysocha@redhat.com>, Dominique Martinet <asmadeus@codewreck.org>, Ilya Dryomov <idryomov@gmail.com>, linux-cachefs@redhat.com, linux-cifs@vger.kernel.org, linux-afs@lists.infradead.org, v9fs-developer@lists.sourceforge.net, ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Jeff Layton <jlayton@kernel.org>, linux-erofs@lists.ozlabs.org, linux-ext4@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 3/3] mm: Make filemap_release_folio() better inform shrink_folio_list() Date: Sat, 7 Jan 2023 15:06:14 +0000 [thread overview] Message-ID: <Y7mKZj/RnD2aW5jU@casper.infradead.org> (raw) In-Reply-To: <Y6XJwvjKyTgRIiI3@infradead.org> On Fri, Dec 23, 2022 at 07:31:14AM -0800, Christoph Hellwig wrote: > On Thu, Dec 22, 2022 at 03:02:29PM +0000, David Howells wrote: > > Make filemap_release_folio() return one of three values: > > > > (0) FILEMAP_CANT_RELEASE_FOLIO > > > > Couldn't release the folio's private data, so the folio can't itself > > be released. > > > > (1) FILEMAP_RELEASED_FOLIO > > > > The private data on the folio was released and the folio can be > > released. > > > > (2) FILEMAP_FOLIO_HAD_NO_PRIVATE > > These names read really odd, due to the different placementments > of FOLIO, the present vs past tense and the fact that 2 also released > the folio, and the reliance of callers that one value of an enum > must be 0, while no unprecedented, is a bit ugly. Agreed. The thing is that it's not the filemap that's being released, it's the folio. So these should be: FOLIO_RELEASE_SUCCESS FOLIO_RELEASE_FAILED FOLIO_RELEASE_NO_PRIVATE ... but of course, NO_PRIVATE is also a success. So it's a really weird thing to be reporting. I'm with you on the latter half of this email: > But do we even need them? What abut just open coding > filemap_release_folio (which is a mostly trivial function) in > shrink_folio_list, which is the only place that cares? > > if (folio_has_private(folio) && folio_needs_release(folio)) { > if (folio_test_writeback(folio)) > goto activate_locked; > > if (mapping && mapping->a_ops->release_folio) { > if (!mapping->a_ops->release_folio(folio, gfp)) > goto activate_locked; > } else { > if (!try_to_free_buffers(folio)) > goto activate_locked; > } > > if (!mapping && folio_ref_count(folio) == 1) { > ... > > alternatively just keep using filemap_release_folio and just add the > folio_needs_release in the first branch. That duplicates the test, > but makes the change a one-liner. Or just drop patch 3 entirely?
WARNING: multiple messages have this Message-ID (diff)
From: Matthew Wilcox <willy@infradead.org> To: Christoph Hellwig <hch@infradead.org> Cc: Shyam Prasad N <nspmangalore@gmail.com>, Steve French <sfrench@samba.org>, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, Rohith Surabattula <rohiths.msft@gmail.com>, Jeff Layton <jlayton@kernel.org>, Dave Wysochanski <dwysocha@redhat.com>, ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-afs@lists.infradead.org, David Howells <dhowells@redhat.com>, linux-mm@kvack.org, linux-cachefs@redhat.com, linux-ext4@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, Ilya Dryomov <idryomov@gmail.com>, Linus Torvalds <torvalds@linux-foundation.org>, Dominique Martinet <asmadeus@codewreck.org> Subject: Re: [PATCH v5 3/3] mm: Make filemap_release_folio() better inform shrink_folio_list() Date: Sat, 7 Jan 2023 15:06:14 +0000 [thread overview] Message-ID: <Y7mKZj/RnD2aW5jU@casper.infradead.org> (raw) In-Reply-To: <Y6XJwvjKyTgRIiI3@infradead.org> On Fri, Dec 23, 2022 at 07:31:14AM -0800, Christoph Hellwig wrote: > On Thu, Dec 22, 2022 at 03:02:29PM +0000, David Howells wrote: > > Make filemap_release_folio() return one of three values: > > > > (0) FILEMAP_CANT_RELEASE_FOLIO > > > > Couldn't release the folio's private data, so the folio can't itself > > be released. > > > > (1) FILEMAP_RELEASED_FOLIO > > > > The private data on the folio was released and the folio can be > > released. > > > > (2) FILEMAP_FOLIO_HAD_NO_PRIVATE > > These names read really odd, due to the different placementments > of FOLIO, the present vs past tense and the fact that 2 also released > the folio, and the reliance of callers that one value of an enum > must be 0, while no unprecedented, is a bit ugly. Agreed. The thing is that it's not the filemap that's being released, it's the folio. So these should be: FOLIO_RELEASE_SUCCESS FOLIO_RELEASE_FAILED FOLIO_RELEASE_NO_PRIVATE ... but of course, NO_PRIVATE is also a success. So it's a really weird thing to be reporting. I'm with you on the latter half of this email: > But do we even need them? What abut just open coding > filemap_release_folio (which is a mostly trivial function) in > shrink_folio_list, which is the only place that cares? > > if (folio_has_private(folio) && folio_needs_release(folio)) { > if (folio_test_writeback(folio)) > goto activate_locked; > > if (mapping && mapping->a_ops->release_folio) { > if (!mapping->a_ops->release_folio(folio, gfp)) > goto activate_locked; > } else { > if (!try_to_free_buffers(folio)) > goto activate_locked; > } > > if (!mapping && folio_ref_count(folio) == 1) { > ... > > alternatively just keep using filemap_release_folio and just add the > folio_needs_release in the first branch. That duplicates the test, > but makes the change a one-liner. Or just drop patch 3 entirely?
next prev parent reply other threads:[~2023-01-07 15:06 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-12-22 15:01 [PATCH v5 0/3] mm, netfs, fscache: Stop read optimisation when folio removed from pagecache David Howells 2022-12-22 15:01 ` David Howells 2022-12-22 15:02 ` [PATCH v5 1/3] mm: Merge folio_has_private()/filemap_release_folio() call pairs David Howells 2022-12-22 15:02 ` David Howells 2023-01-07 15:11 ` Matthew Wilcox 2023-01-07 15:11 ` Matthew Wilcox 2022-12-22 15:02 ` [PATCH v5 2/3] mm, netfs, fscache: Stop read optimisation when folio removed from pagecache David Howells 2022-12-22 15:02 ` David Howells 2023-02-16 13:58 ` David Wysochanski 2023-02-16 13:58 ` David Wysochanski 2022-12-22 15:02 ` [PATCH v5 3/3] mm: Make filemap_release_folio() better inform shrink_folio_list() David Howells 2022-12-22 15:02 ` David Howells 2022-12-23 15:31 ` Christoph Hellwig 2022-12-23 15:31 ` Christoph Hellwig 2023-01-07 15:06 ` Matthew Wilcox [this message] 2023-01-07 15:06 ` Matthew Wilcox
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