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bh=zXehXAXIEmYYeqDh0Eogjo6VOr6C1m5T64ivWJ24wcQ=; b=Vxr/hBQEi90TuscbFQV/HaSCLfVBeGFcYfC9pSGkw1JM1bJ7O6/8lGar26+RcLW4OlbUlb DcQMfg9YhaMLL/vzJAb9CL7mQl5zjEStqSA+4G0ClSj248X9b5LTmqY5I8vxXJXuPystWs 2H0Y+NlvZAP0b9UxUDnUqvV9nflG3WvAf3/T/hmg/v9EHi86TArZNEBmuFT4WYyRkil/NY zSZ5NzUamAXJWaJYjglAmwSCPPwhiKKFsucsuqthi4y7vcyWuIIL6hPa2N1MewHvnwAUSs mtxNXlWOjT8BPeJM3cdi1rClYkw2Fuc6kklS03TgcDEEtCLnQA6beIK114JV8w== Date: Tue, 27 Feb 2024 17:55:35 +0100 From: "Pankaj Raghav (Samsung)" To: Kent Overstreet Cc: Matthew Wilcox , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, david@fromorbit.com, chandan.babu@oracle.com, akpm@linux-foundation.org, mcgrof@kernel.org, ziy@nvidia.com, hare@suse.de, djwong@kernel.org, gost.dev@samsung.com, linux-mm@kvack.org, Pankaj Raghav Subject: Re: [PATCH 03/13] filemap: align the index to mapping_min_order in the page cache Message-ID: <4zpsfvy3e4hkc4avvjjr34rgo7ggpd6hpflptmiauvxwm3dpvk@5wulihwpwbyp> References: <20240226094936.2677493-1-kernel@pankajraghav.com> <20240226094936.2677493-4-kernel@pankajraghav.com> <37kubwweih4zwvxzvjbhnhxunrafawdqaqggzcw6xayd6vtrfl@dllnk6n53akf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AA0DF40013 X-Stat-Signature: 9yap6i119c1um167w79kxa5ti7jpjpj9 X-HE-Tag: 1709052943-262000 X-HE-Meta: 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 vzr09HqF 3dHumVNfQ3J8O+I7AogTXYxxz/+bN/wLq19XPXi1liChYtjLUmPE3Vgl5PmOtvewEfiSPM0p0r90Q3zB8FHcJ7pzvr3Y+SBMC0HbxdniJ949ga4rb6d0aEE07tXhkht2/YqGGT6nUn5veExwh/KUdvEivFA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.001014, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > > > > > > you guys are both wrong, just use rounddown() > > > > Umm, what do you mean just use rounddown? rounddown to ...? > > > > We need to get index that are in PAGE units but aligned to min_order > > pages. > > > > The original patch did this: > > > > index = mapping_align_start_index(mapping, iocb->ki_pos >> PAGE_SHIFT); > > > > Which is essentially a rounddown operation (probably this is what you > > are suggesting?). > > > > So what willy is proposing will do the same. To me, what I proposed is > > less complicated but to willy it is the other way around. > > Ok, I just found the code for mapping_align_start_index() - it is just a > round_down(). > > Never mind; patch looks fine (aside from perhaps some quibbling over > whether the round_down()) should be done before calling readahead or > within readahead; I think that might have been more what willy was > keying in on) Yeah, exactly. I have one question while I have you here. When we have this support in the page cache, do you think bcachefs can make use of this support to enable bs > ps in bcachefs as it already makes use of large folios? Do you think it is just a simple mapping_set_large_folios -> mapping_set_folio_min_order(.., block_size order) or it requires more effort?