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Thu, 21 Dec 2023 12:49:44 +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 tccNMWg0hGX/dgAAD6G6ig (envelope-from ); Thu, 21 Dec 2023 12:49:44 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 859EAA07E3; Thu, 21 Dec 2023 13:49:36 +0100 (CET) Date: Thu, 21 Dec 2023 13:49:36 +0100 From: Jan Kara To: Christoph Hellwig Cc: Jan Kara , 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 15/17] writeback: Add for_each_writeback_folio() Message-ID: <20231221124936.vmm2tjujoy6roxs4@quack3> References: <20231218153553.807799-1-hch@lst.de> <20231218153553.807799-16-hch@lst.de> <20231221115149.ke74ddapwb7q6fdz@quack3> <20231221122910.GF17956@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231221122910.GF17956@lst.de> X-Stat-Signature: oujz1nigyc3f9szwf8suns195kimowun X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: EE15518000D X-Rspam-User: X-HE-Tag: 1703162986-53802 X-HE-Meta: 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 BdZCWZMp 6wafaez7en3UWB4yAY5ZXeGl/GzRCopAAZor9qL2oPDKPKD5hp8k/fByLEbmB+SXAOoyuaZfjT0vtTes7pEMoV52hB/TCTg7AuC9Im46OovfxsVAG7HiqWy0ra2BgnANpKTduGHLpytYzH5uzbkt0PZ1rNSCNkWJWQHsy8F8lQkzexy07JpViD/oQH49oj1z/zkVtLCOI9YQi/UnDKPnY79x6/3MiLPij4Ap4i/oWeuOd3zm/D+Fu3/d7PH8rv/pyF9X7VJnYfyBm3y8faf7dajFHr1EjIPzdOGJsOunmfNuSyZrV4bEiQ/KqfMi9248qN69SsT37iqMbCaf9OH0u56H1K8rYeB7s1Si0azgL28RBs7w8wlNwcXr8wbjuPAoxBPou 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 Thu 21-12-23 13:29:10, Christoph Hellwig wrote: > On Thu, Dec 21, 2023 at 12:51:49PM +0100, Jan Kara wrote: > > On Mon 18-12-23 16:35:51, Christoph Hellwig wrote: > > > From: "Matthew Wilcox (Oracle)" > > > > > > Wrap up the iterator with a nice bit of syntactic sugar. Now the > > > caller doesn't need to know about wbc->err and can just return error, > > > not knowing that the iterator took care of storing errors correctly. > > > > > > Signed-off-by: Matthew Wilcox (Oracle) > > > Signed-off-by: Christoph Hellwig > > > > Not sure if the trick with 'error' variable isn't a bit too clever for us > > ;) We'll see how many bugs it will cause in the future... > > It's a bit too much syntactic sugar for my taste, but if we want a magic > for macro I can't really see a good way around it. I personally wouldn't Agreed. The macro is kind of neat but a magic like this tends to bite us in surprising ways. E.g. if someone breaks out of the loop, things will go really wrong (missing writeback_finish() call). That would be actually a good usecase for the cleanup handlers PeterZ has been promoting - we could make sure writeback_finish() is called whenever we exit the loop block. > mind a version where the writeback_get_folio moves out of > writeback_iter_init and the pattern would look more like: > > writeback_iter_init(mapping, wbc); > while ((folio = writeback_iter_next(mapping, wbc, folio))) { > wbc->err = > } > > return wbc->err; That would work for me as well. But I don't feel to strongly about this either way. Honza -- Jan Kara SUSE Labs, CR