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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qY3tZ-00A7pc-KQ; Mon, 21 Aug 2023 12:20:33 +0000 Date: Mon, 21 Aug 2023 13:20:33 +0100 From: Matthew Wilcox To: Jan Kara Cc: Xueshi Hu , dan.j.williams@intel.com, vishal.l.verma@intel.com, dave.jiang@intel.com, jayalk@intworks.biz, daniel@ffwll.ch, deller@gmx.de, bcrl@kvack.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.com, tytso@mit.edu, adilger.kernel@dilger.ca, miklos@szeredi.hu, mike.kravetz@oracle.com, muchun.song@linux.dev, djwong@kernel.org, akpm@linux-foundation.org, hughd@google.com, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH] fs: clean up usage of noop_dirty_folio Message-ID: References: <20230819124225.1703147-1-xueshi.hu@smartx.com> <20230821111643.5vxtktznjqk42cak@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230821111643.5vxtktznjqk42cak@quack3> X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: E936918001E X-Stat-Signature: gg31uyyxknemrdiiy8mjpwsunuoy698f X-HE-Tag: 1692620443-75750 X-HE-Meta: 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 gfqYR2oE VFJUhig6nTrGRJN7T9YG6xU3LOvBUpnyIrXsrHXLXoHGiKXfbc7NyIYyzH4Y4+V+H8b1zbFGv7jrpOraIRieeX3UV7Lk9st/QCG98OHBuJ+5RxuLGN9l2OSADjudFLyCt999F7Rek0OlGg6reiVZKDAZ5L7uxRVNT/0/8+d/MqsS1N64hyfDC4CvuqRG/GaZBRqIdsSe4PMyx75WxYqwlyVOlZjfh7ttS5j8LLXdNKT8yQ7of3BOFxNrgPQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 21, 2023 at 01:16:43PM +0200, Jan Kara wrote: > On Sat 19-08-23 20:42:25, Xueshi Hu wrote: > > In folio_mark_dirty(), it will automatically fallback to > > noop_dirty_folio() if a_ops->dirty_folio is not registered. > > > > As anon_aops, dev_dax_aops and fb_deferred_io_aops becames empty, remove > > them too. > > > > Signed-off-by: Xueshi Hu > > Yeah, looks sensible to me but for some callbacks we are oscilating between > all users having to provide some callback and providing some default > behavior for NULL callback. I don't have a strong opinion either way so > feel free to add: > > Reviewed-by: Jan Kara > > But I guess let's see what Matthew thinks about this and what plans he has > so that we don't switch back again in the near future. Matthew? I was hoping Christoph would weigh in ;-) I don't have a strong feeling here, but it seems to me that a NULL ->dirty_folio() should mean "do the noop thing" rather than "do the buffer_head thing" or "do the filemap thing". In 0af573780b0b, the buffer_head default was removed. I think enough time has passed that we're OK to change what a NULL ->dirty_folio means (plus we also changed the name of ->set_page_dirty() to ->dirty_folio()) So Ack to the concept. One minor change I'd request: -bool noop_dirty_folio(struct address_space *mapping, struct folio *folio) +static bool noop_dirty_folio(struct address_space *mapping, struct folio *folio) { if (!folio_test_dirty(folio)) return !folio_test_set_dirty(folio); return false; } -EXPORT_SYMBOL(noop_dirty_folio); Please inline this into folio_mark_dirty() instead of calling it.