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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uXIO1-0000000CwiZ-3tcP; Thu, 03 Jul 2025 11:45:53 +0000 Date: Thu, 3 Jul 2025 12:45:53 +0100 From: Matthew Wilcox To: "hch@infradead.org" Cc: =?utf-8?B?6ZmI5rab5rab?= Taotao Chen , "tytso@mit.edu" , "adilger.kernel@dilger.ca" , "brauner@kernel.org" , "jani.nikula@linux.intel.com" , "rodrigo.vivi@intel.com" , "tursulin@ursulin.net" , "airlied@gmail.com" , "linux-fsdevel@vger.kernel.org" , "linux-ext4@vger.kernel.org" , "linux-block@vger.kernel.org" , "intel-gfx@lists.freedesktop.org" , "dri-devel@lists.freedesktop.org" , "linux-mm@kvack.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "chentao325@qq.com" , "frank.li@vivo.com" Subject: Re: [PATCH v3 4/4] ext4: support uncached buffered I/O Message-ID: References: <20250627110257.1870826-1-chentaotao@didiglobal.com> <20250627110257.1870826-5-chentaotao@didiglobal.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 51DCA40011 X-Stat-Signature: n66iqxdumwa1uw8jje7ts4setwxgsooo X-Rspam-User: X-HE-Tag: 1751543169-568244 X-HE-Meta: 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 DB2PM984 SA7pZ0y8UlMgQ48fU3u/iTUWGZIz17a52WjdafIB42JEFRc5qJaX5UifomwtuSeFdgq71/ru5IYOTXA46cMzGXgizCzgvIfMWLxGwXSBCiSQICQjPPtZ0S+TBeyOzLDdepAhVTNRHFVJI7VB+DrB2tWft1RgRGZ/zkzfPVRSPYU/HpFNz0oFSRhI5YYqnupfwFAw/6wSMSNSFVQgHm89IkhTro8YjstjraHZ8qL3H567ypdmQ+B1g1KVMG1WXki+yZhv3zpFumnEfMbeQ330u42jZy2DOOHYwF14RmRFKCjini50= 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 Sun, Jun 29, 2025 at 11:41:12PM -0700, hch@infradead.org wrote: > On Fri, Jun 27, 2025 at 06:03:09PM +0100, Matthew Wilcox wrote: > > On Fri, Jun 27, 2025 at 11:03:13AM +0000, 陈涛涛 Taotao Chen wrote: > > I think this needs to be: > > > > if (iocb && iocb->ki_flags & IOCB_DONTCACHE) > > > > because it's legit to call write_begin with a NULL argument. The > > 'file' was always an optional argument, and we should preserve that > > optionality with this transformation. > > write_begin and write_end are only callbacks through helpers called > by the file system. So if the file system never passes a NULL > file/kiocb it doesn't need to check for it. Sure, but some of those helpers are non-obvious, like page_symlink().