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[209.85.208.171]) by smtp.gmail.com with ESMTPSA id d19-v6sm1140165ljc.37.2019.01.31.23.05.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 31 Jan 2019 23:05:49 -0800 (PST) Received: by mail-lj1-f171.google.com with SMTP id s5-v6so4830171ljd.12 for ; Thu, 31 Jan 2019 23:05:49 -0800 (PST) X-Received: by 2002:a2e:8045:: with SMTP id p5-v6mr29493803ljg.87.1549004749092; Thu, 31 Jan 2019 23:05:49 -0800 (PST) MIME-Version: 1.0 References: <20190130124420.1834-1-vbabka@suse.cz> <20190130124420.1834-3-vbabka@suse.cz> <20190131095644.GR18811@dhcp22.suse.cz> <20190131102348.GT18811@dhcp22.suse.cz> <20190201051355.GV6173@dastard> In-Reply-To: <20190201051355.GV6173@dastard> From: Linus Torvalds Date: Thu, 31 Jan 2019 23:05:32 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 2/3] mm/filemap: initiate readahead even if IOCB_NOWAIT is set for the I/O To: Dave Chinner Cc: Michal Hocko , Jiri Kosina , Vlastimil Babka , Andrew Morton , Linux List Kernel Mailing , Linux-MM , Linux API , Peter Zijlstra , Greg KH , Jann Horn , Dominique Martinet , Andy Lutomirski , Kevin Easton , Matthew Wilcox , Cyril Hrubis , Tejun Heo , "Kirill A . Shutemov" , Daniel Gruss , linux-fsdevel Content-Type: text/plain; charset="UTF-8" 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: On Thu, Jan 31, 2019 at 9:16 PM Dave Chinner wrote: > > You are conflating "best effort non-blocking operation" with > "atomic guarantee". RWF_NOWAIT/IOCB_NOWAIT is the > former, not the latter. Right. That's my *point*, Dave. It's not 'atomic guarantee", and never will be. We are in 100% agreement. That's what I _said_. And part of "best effort" is very much "not a security information leak". I really don't see why you are so argumentative. As I mentioned earlier in the thread, it's actually quite possible that users will actually find that starting read-ahead is a *good* thing, Dave. Even - in fact *particularly* - the user you brought up: samba using RWF_NOWAIT to try to do things synchronously quickly. So Dave, why are you being so negative? Linus