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Thu, 21 Dec 2023 10:59:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Rj8PLZoahGUxUQAAD6G6ig (envelope-from ); Thu, 21 Dec 2023 10:59:38 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 5BB51A07E3; Thu, 21 Dec 2023 11:59:34 +0100 (CET) Date: Thu, 21 Dec 2023 11:59:34 +0100 From: Jan Kara To: Christoph Hellwig Cc: linux-mm@kvack.org, "Matthew Wilcox (Oracle)" , Jan Kara , David Howells , Brian Foster , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 04/17] writeback: only update ->writeback_index for range_cyclic writeback Message-ID: <20231221105934.6bhdl73siuu3fct6@quack3> References: <20231218153553.807799-1-hch@lst.de> <20231218153553.807799-5-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231218153553.807799-5-hch@lst.de> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0CC0E40012 X-Stat-Signature: csijf1gdsczf4uj49yunynmr9q4s79nq X-Rspam-User: X-HE-Tag: 1703156381-402895 X-HE-Meta: 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 q+G5iMuT idCEHXKzuWF20e5i1tT6y2F833V6dkY8STsMwQT6nj1roBfBg4b0DVJlbosNIyKNiSrkmDY2y9VNUdSM6evlHNG7z+MQG/D/g82yccbM7VLK2uriVIXPCEJj70VGAOVKegZzaj3WaZAg+r9Fb8Ph0hB4uXQqz/MAymbqRCfPdjkyyRaC8iGzqJSsgMfWe/DiAKjCPy60bsZ9oMYPF1otLfRC/imTCOVsnWshMgEnJr3DAJPvegZpZ5IsP3cY/8RAYW5KGA5KJhRxzIKEVrfk55sCYLmMa6TRsDiSUfzl/75ioTZsRodY9LQ1HGceQBL5qulAj 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: List-Subscribe: List-Unsubscribe: On Mon 18-12-23 16:35:40, Christoph Hellwig wrote: > mapping->writeback_index is only [1] used as the starting point for > range_cyclic writeback, so there is no point in updating it for other > types of writeback. > > [1] except for btrfs_defrag_file which does really odd things with > mapping->writeback_index. But btrfs doesn't use write_cache_pages at > all, so this isn't relevant here. > > Signed-off-by: Christoph Hellwig Looks good. Feel free to add: Reviewed-by: Jan Kara Honza > --- > mm/page-writeback.c | 24 ++++++++++++++---------- > 1 file changed, 14 insertions(+), 10 deletions(-) > > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > index 7ed6c2bc8dd51c..c798c0d6d0abb4 100644 > --- a/mm/page-writeback.c > +++ b/mm/page-writeback.c > @@ -2403,7 +2403,6 @@ int write_cache_pages(struct address_space *mapping, > pgoff_t index; > pgoff_t end; /* Inclusive */ > pgoff_t done_index; > - int range_whole = 0; > xa_mark_t tag; > > folio_batch_init(&fbatch); > @@ -2413,8 +2412,6 @@ int write_cache_pages(struct address_space *mapping, > } else { > index = wbc->range_start >> PAGE_SHIFT; > end = wbc->range_end >> PAGE_SHIFT; > - if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) > - range_whole = 1; > } > if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) { > tag_pages_for_writeback(mapping, index, end); > @@ -2514,14 +2511,21 @@ int write_cache_pages(struct address_space *mapping, > } > > /* > - * If we hit the last page and there is more work to be done: wrap > - * back the index back to the start of the file for the next > - * time we are called. > + * For range cyclic writeback we need to remember where we stopped so > + * that we can continue there next time we are called. If we hit the > + * last page and there is more work to be done, wrap back to the start > + * of the file. > + * > + * For non-cyclic writeback we always start looking up at the beginning > + * of the file if we are called again, which can only happen due to > + * -ENOMEM from the file system. > */ > - if (wbc->range_cyclic && !done) > - done_index = 0; > - if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) > - mapping->writeback_index = done_index; > + if (wbc->range_cyclic) { > + if (done) > + mapping->writeback_index = done_index; > + else > + mapping->writeback_index = 0; > + } > > return ret; > } > -- > 2.39.2 > -- Jan Kara SUSE Labs, CR