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Wed, 24 Jan 2024 06:27:44 +0100 Message-ID: <45066165-3d2d-4026-87d3-2cfe3369a86b@gmx.com> Date: Wed, 24 Jan 2024 15:57:39 +1030 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 0/2] btrfs: defrag: further preparation for multi-page sector size Content-Language: en-US To: Matthew Wilcox , Qu Wenruo Cc: linux-btrfs@vger.kernel.org, Linux Memory Management List References: From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00iVQUJDToH pgAKCRDCPZHzoSX+qNKACACkjDLzCvcFuDlgqCiS4ajHAo6twGra3uGgY2klo3S4JespWifr BLPPak74oOShqNZ8yWzB1Bkz1u93Ifx3c3H0r2vLWrImoP5eQdymVqMWmDAq+sV1Koyt8gXQ XPD2jQCrfR9nUuV1F3Z4Lgo+6I5LjuXBVEayFdz/VYK63+YLEAlSowCF72Lkz06TmaI0XMyj jgRNGM2MRgfxbprCcsgUypaDfmhY2nrhIzPUICURfp9t/65+/PLlV4nYs+DtSwPyNjkPX72+ LdyIdY+BqS8cZbPG5spCyJIlZonADojLDYQq4QnufARU51zyVjzTXMg5gAttDZwTH+8LbNI4 mm2YzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00ibgUJDToHvwAK CRDCPZHzoSX+qK6vB/9yyZlsS+ijtsvwYDjGA2WhVhN07Xa5SBBvGCAycyGGzSMkOJcOtUUf tD+ADyrLbLuVSfRN1ke738UojphwkSFj4t9scG5A+U8GgOZtrlYOsY2+cG3R5vjoXUgXMP37 INfWh0KbJodf0G48xouesn08cbfUdlphSMXujCA8y5TcNyRuNv2q5Nizl8sKhUZzh4BascoK DChBuznBsucCTAGrwPgG4/ul6HnWE8DipMKvkV9ob1xJS2W4WJRPp6QdVrBWJ9cCdtpR6GbL iQi22uZXoSPv/0oUrGU+U5X4IvdnvT+8viPzszL5wXswJZfqfy8tmHM85yjObVdIG6AlnrrD In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:sdRr7enkzJUnUrfC1ucxKu4e0z4cpg3Uw6UgzndZ+7iXIZmkB78 HOwowTq3jnzEua4Lrji6ikk+PPbV1WMOtQ4k3fT9ebH09g9g7VhPNa2Bsxei2PrGSG0sQ+Q vCvlKaId/jq73PL0QY/K9sTv+GEa3BYWPLuZiEA/U34ju9ZGaLII0QIK29RY/sQv2ou+y/+ /ATh4S3yU4NpnB2Jb3FrQ== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:Q5CsCIr2egU=;jvQwTsCnm694ZhcG0vwACfb7H7B MyA/BOiZ5tmtWZlr5M4mxxWdogIudNa54ybrIemOPL1d0cP4maAf2QIPn9lX8KsBT98WTzdSR Y5yV2Y4P8YoIjBTqHyxp4OYa/FVzVgVlgjzm05JR/nrM9pjpBjgCatwClLrjDg9pFrKBJ+2SH WhoaH/2NtE2AH/1i5JZivxN8U24uqWgWizJsvAdw+hK3Tzsk9WvzV0m1r6BpCcy7TznfJ5kWR kEfSj8vEmYfm9GMG61rFGoDuti6smjqf9HwUtudscC+hLKqsvXl1Xkcv4LeVyKasulReSuf+g O40DmZLE6NrivFMn8ocPQXjy/q6lKQbM0SeKLf+c+Qn/UzBAopFwe5qzfu6K4vyCrhGvAt74h 6UuyRGYsWXFncFFDV79dWQNbOlFGrSRRUv+shhISWWsIaN19+chrBUoTi+ao/tv2k4szlhhkv qLzt/9BdeFl1zSrQaC5LcGsefGCnsQXIRIX85cXxMshZ0sBsK8lXwATH9184yR2VsQ3ukBpMn zhWAJuy7K3xhpXmOJEvLVTCTgQVfPM6X8xbPnu10kKjxBv2dKFN251dQ7N7LVHdddgLeRay7H Qo7wY0cZzZbYhUya/reAWwquVAM5s3tm3k9oLwCg/rT7of6efwiViTDsCANT0anpn0fNt+akQ zuRy165JOK+Jtr0GbS+kYNJzBUMHzPZyKukUKv1u+bsuZf1ZuruHdutxTaI3P4bSuhxC60I2P Fn3Wu+RhhUIR89v3M4tB8dd8e16u3sY4/i0s5h25bZ6xjBaVR8Hf/xxOeamPG7oX8woumTK8B PJuIbuyeyG2FjXdDbP8CjuFiZdFit7BRwT1c8I0UCDsRpjOVC6vyKCOwHS4vhLbVqqz9c2zxT laBZ9SJjnlCVF5Ez3N8mz9uPdIBx3oXJDM0w8hioHX3yPmlNQ/C8gl1f6/P+sfL9ubiW+chcg TghLa2sz5hIIrI38myS1rI43oYQ= On 2024/1/24 15:18, Matthew Wilcox wrote: > On Wed, Jan 24, 2024 at 02:33:22PM +1030, Qu Wenruo wrote: >> I'm pretty sure we would have some filesystems go utilizing larger foli= os to >> implement their multi-page block size support. >> >> Thus in that case, can we have an interface change to make all folio >> versions of filemap_*() to accept a file offset instead of page index? > > You're confused. There's no change needed to the filemap API to support > large folios used by large block sizes. Quite possibly more of btrfs > is confused, but it's really very simple. index =3D=3D pos / PAGE_SIZE. > That's all. Even if you have a 64kB block size device on a 4kB PAGE_SIZ= E > machine. Yes, I understand that filemap API is always working on PAGE_SHIFTed index= . The concern is, (hopefully) with more fses going to utilized large folios, there would be two shifts. One folio shift (ilog2(blocksize)), one PAGE_SHIFT for filemap interfaces. And I'm pretty sure it's going to cause confusion, e.g. someone doing the conversion without much think, and all go the folio shift, even for filemap_get_folio(). Thus I'm wondering if it's possible to get a bytenr version of filemap_get_folio(). (Or is it better just creating an inline wrapper inside the fs to avoid confusion?) > > That implies that folios must be at least order-4, but you can still > look up a folio at index 23 and get back the folio which was stored at > index 16 (range 16-31). Yep, that's also what I expect, and that is very handy. Thanks, Qu > > hugetlbfs made the mistake of 'hstate->order' and it's still not fixed. > It's a little better than it was (thanks to Sid), but more work is neede= d. > Just use the same approach as THPs or you're going to end up hurt. >