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([2600:1700:6476:1430:f030:281a:9e2c:722]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7166599fc22sm4941937b3.28.2025.07.04.10.37.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Jul 2025 10:37:55 -0700 (PDT) Message-ID: <9d9d7bbab5443bd1c3dfd7d81d9bc91debecf4ef.camel@dubeyko.com> Subject: Re: [PATCH 4/4] hfs: enable uncached buffer io support From: Viacheslav Dubeyko To: Yangtao Li , axboe@kernel.dk, aivazian.tigran@gmail.com, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linkinjeon@kernel.org, sj1557.seo@samsung.com, yuezhang.mo@sony.com, glaubitz@physik.fu-berlin.de, shaggy@kernel.org, konishi.ryusuke@gmail.com, almaz.alexandrovich@paragon-software.com, me@bobcopeland.com, willy@infradead.org, josef@toxicpanda.com, kovalev@altlinux.org, dave@stgolabs.net, mhocko@suse.com, chentaotao@didiglobal.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, jfs-discussion@lists.sourceforge.net, linux-nilfs@vger.kernel.org, ntfs3@lists.linux.dev, linux-karma-devel@lists.sourceforge.net, bpf@vger.kernel.org Date: Fri, 04 Jul 2025 10:37:52 -0700 In-Reply-To: <20250626173023.2702554-5-frank.li@vivo.com> References: <20250626173023.2702554-1-frank.li@vivo.com> <20250626173023.2702554-5-frank.li@vivo.com> Autocrypt: addr=slava@dubeyko.com; prefer-encrypt=mutual; keydata=mQINBGgaTLYBEADaJc/WqWTeunGetXyyGJ5Za7b23M/ozuDCWCp+yWUa2GqQKH40dxRIR zshgOmAue7t9RQJU9lxZ4ZHWbi1Hzz85+0omefEdAKFmxTO6+CYV0g/sapU0wPJws3sC2Pbda9/eJ ZcvScAX2n/PlhpTnzJKf3JkHh3nM1ACO3jzSe2/muSQJvqMLG2D71ccekr1RyUh8V+OZdrPtfkDam V6GOT6IvyE+d+55fzmo20nJKecvbyvdikWwZvjjCENsG9qOf3TcCJ9DDYwjyYe1To8b+mQM9nHcxp jUsUuH074BhISFwt99/htZdSgp4csiGeXr8f9BEotRB6+kjMBHaiJ6B7BIlDmlffyR4f3oR/5hxgy dvIxMocqyc03xVyM6tA4ZrshKkwDgZIFEKkx37ec22ZJczNwGywKQW2TGXUTZVbdooiG4tXbRBLxe ga/NTZ52ZdEkSxAUGw/l0y0InTtdDIWvfUT+WXtQcEPRBE6HHhoeFehLzWL/o7w5Hog+0hXhNjqte fzKpI2fWmYzoIb6ueNmE/8sP9fWXo6Av9m8B5hRvF/hVWfEysr/2LSqN+xjt9NEbg8WNRMLy/Y0MS p5fgf9pmGF78waFiBvgZIQNuQnHrM+0BmYOhR0JKoHjt7r5wLyNiKFc8b7xXndyCDYfniO3ljbr0j tXWRGxx4to6FwARAQABtCZWaWFjaGVzbGF2IER1YmV5a28gPHNsYXZhQGR1YmV5a28uY29tPokCVw QTAQoAQQIbAQUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBFXDC2tnzsoLQtrbBDlc2cL fhEB1BQJoGl5PAhkBAAoJEDlc2cLfhEB17DsP/jy/Dx19MtxWOniPqpQf2s65enkDZuMIQ94jSg7B F2qTKIbNR9SmsczjyjC+/J7m7WZRmcqnwFYMOyNfh12aF2WhjT7p5xEAbvfGVYwUpUrg/lcacdT0D Yk61GGc5ZB89OAWHLr0FJjI54bd7kn7E/JRQF4dqNsxU8qcPXQ0wLHxTHUPZu/w5Zu/cO+lQ3H0Pj pSEGaTAh+tBYGSvQ4YPYBcV8+qjTxzeNwkw4ARza8EjTwWKP2jWAfA/ay4VobRfqNQ2zLoo84qDtN Uxe0zPE2wobIXELWkbuW/6hoQFPpMlJWz+mbvVms57NAA1HO8F5c1SLFaJ6dN0AQbxrHi45/cQXla 9hSEOJjxcEnJG/ZmcomYHFneM9K1p1K6HcGajiY2BFWkVet9vuHygkLWXVYZ0lr1paLFR52S7T+cf 6dkxOqu1ZiRegvFoyzBUzlLh/elgp3tWUfG2VmJD3lGpB3m5ZhwQ3rFpK8A7cKzgKjwPp61Me0o9z HX53THoG+QG+o0nnIKK7M8+coToTSyznYoq9C3eKeM/J97x9+h9tbizaeUQvWzQOgG8myUJ5u5Dr4 6tv9KXrOJy0iy/dcyreMYV5lwODaFfOeA4Lbnn5vRn9OjuMg1PFhCi3yMI4lA4umXFw0V2/OI5rgW BQELhfvW6mxkihkl6KLZX8m1zcHitCpWaWFjaGVzbGF2IER1YmV5a28gPFNsYXZhLkR1YmV5a29Aa WJtLmNvbT6JAlQEEwEKAD4WIQRVwwtrZ87KC0La2wQ5XNnC34RAdQUCaBpd7AIbAQUJA8JnAAULCQ gHAgYVCgkICwIEFgIDAQIeAQIXgAAKCRA5XNnC34RAdYjFEACiWBEybMt1xjRbEgaZ3UP5i2bSway DwYDvgWW5EbRP7JcqOcZ2vkJwrK3gsqC3FKpjOPh7ecE0I4vrabH1Qobe2N8B2Y396z24mGnkTBbb 16Uz3PC93nFN1BA0wuOjlr1/oOTy5gBY563vybhnXPfSEUcXRd28jI7z8tRyzXh2tL8ZLdv1u4vQ8 E0O7lVJ55p9yGxbwgb5vXU4T2irqRKLxRvU80rZIXoEM7zLf5r7RaRxgwjTKdu6rYMUOfoyEQQZTD 4Xg9YE/X8pZzcbYFs4IlscyK6cXU0pjwr2ssjearOLLDJ7ygvfOiOuCZL+6zHRunLwq2JH/RmwuLV mWWSbgosZD6c5+wu6DxV15y7zZaR3NFPOR5ErpCFUorKzBO1nA4dwOAbNym9OGkhRgLAyxwpea0V0 ZlStfp0kfVaSZYo7PXd8Bbtyjali0niBjPpEVZdgtVUpBlPr97jBYZ+L5GF3hd6WJFbEYgj+5Af7C UjbX9DHweGQ/tdXWRnJHRzorxzjOS3003ddRnPtQDDN3Z/XzdAZwQAs0RqqXrTeeJrLppFUbAP+HZ TyOLVJcAAlVQROoq8PbM3ZKIaOygjj6Yw0emJi1D9OsN2UKjoe4W185vamFWX4Ba41jmCPrYJWAWH fAMjjkInIPg7RLGs8FiwxfcpkILP0YbVWHiNAaQ== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.1 (by Flathub.org) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2025-06-26 at 11:30 -0600, Yangtao Li wrote: > Now cont_write_begin() support DONTCACHE mode, let's set > FOP_DONTCACHE > flag to enable uncached buffer io support for hfs. >=20 > Signed-off-by: Yangtao Li > --- > =C2=A0fs/hfs/inode.c | 1 + > =C2=A01 file changed, 1 insertion(+) >=20 > diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c > index 8409e4412366..a62f45e9745d 100644 > --- a/fs/hfs/inode.c > +++ b/fs/hfs/inode.c > @@ -695,6 +695,7 @@ static const struct file_operations > hfs_file_operations =3D { > =C2=A0 .fsync =3D hfs_file_fsync, > =C2=A0 .open =3D hfs_file_open, > =C2=A0 .release =3D hfs_file_release, > + .fop_flags =3D FOP_DONTCACHE, > =C2=A0}; > =C2=A0 > =C2=A0static const struct inode_operations hfs_file_inode_operations =3D = { Frankly speaking, I am not convinced that HFS really need to support this feature. It is old and pretty obsolete file system. The main use- case is simply support the capability to mount HFS volume is created under Mac OS X, for example, and to access the data there. Of course, we can support this feature, but what is the point of this? As far as I can see, the goal of RWF_DONTCACHE feature is: "Common for both reads and writes with RWF_DONTCACHE is that they use the page cache for IO. Reads work just like a normal buffered read would, with the only exception being that the touched ranges will get pruned after data has been copied. For writes, the ranges will get writeback kicked off before the syscall returns, and then writeback completion will prune the range." So, who would like to see such efficiency in HFS? Do we really need to support it in HFS? I think that it is not. Thanks, Slava. =20