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[209.85.167.41]) by smtp.gmail.com with ESMTPSA id v11sm717778lfg.39.2020.09.18.11.02.38 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Sep 2020 11:02:38 -0700 (PDT) Received: by mail-lf1-f41.google.com with SMTP id u8so7077851lff.1 for ; Fri, 18 Sep 2020 11:02:38 -0700 (PDT) X-Received: by 2002:ac2:4a6a:: with SMTP id q10mr10344146lfp.534.1600452157810; Fri, 18 Sep 2020 11:02:37 -0700 (PDT) MIME-Version: 1.0 References: <20200918131317.GH18920@quack2.suse.cz> In-Reply-To: <20200918131317.GH18920@quack2.suse.cz> From: Linus Torvalds Date: Fri, 18 Sep 2020 11:02:21 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: the "read" syscall sees partial effects of the "write" syscall To: Jan Kara Cc: Mikulas Patocka , Dan Williams , Alexander Viro , Andrew Morton , Matthew Wilcox , Eric Sandeen , Dave Chinner , Linux Kernel Mailing List , linux-fsdevel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 18, 2020 at 6:13 AM Jan Kara wrote: > > Yes, but no Linux filesystem (except for XFS AFAIK) follows the POSIX spec > in this regard. Yeah, and we never have. As you say, performance sucks, and nobody has ever cared. So the standard in this case is just something that we'll never follow, and should just be ignored. It's irrelevant. There are other places we don't follow POSIX either. Feel free to document it (I think it's currently just a "everybody knows" kind of undocumented thing). Linus