From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f47.google.com (mail-qg0-f47.google.com [209.85.192.47]) by kanga.kvack.org (Postfix) with ESMTP id CCD3E6B0032 for ; Fri, 9 Jan 2015 14:30:54 -0500 (EST) Received: by mail-qg0-f47.google.com with SMTP id q108so10483840qgd.6 for ; Fri, 09 Jan 2015 11:30:54 -0800 (PST) Received: from mail-qa0-x22c.google.com (mail-qa0-x22c.google.com. [2607:f8b0:400d:c00::22c]) by mx.google.com with ESMTPS id k32si13386086qge.43.2015.01.09.11.30.52 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 09 Jan 2015 11:30:53 -0800 (PST) Received: by mail-qa0-f44.google.com with SMTP id w8so699916qac.3 for ; Fri, 09 Jan 2015 11:30:52 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20150108114950.GB3351@infradead.org> References: <1414185652-28663-1-git-send-email-matthew.r.wilcox@intel.com> <20141210140347.GA23252@infradead.org> <20141210141211.GD2220@wil.cx> <20150105184143.GA665@infradead.org> <20150106004714.6d63023c.akpm@linux-foundation.org> <20150108114950.GB3351@infradead.org> From: Steve French Date: Fri, 9 Jan 2015 13:30:31 -0600 Message-ID: Subject: Re: pread2/ pwrite2 Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Hellwig Cc: Andrew Morton , linux-fsdevel , LKML , linux-mm , Linus Torvalds , Milosz Tanski On Thu, Jan 8, 2015 at 5:49 AM, Christoph Hellwig wrote: > On Tue, Jan 06, 2015 at 12:47:14AM -0800, Andrew Morton wrote: >> > progress, which is a bit frustrating. >> >> I took a look at pread2() as well and I have two main issues: >> >> - The patchset includes a pwrite2() syscall which has nothing to do >> with nonblocking reads and which was poorly described and had little >> justification for inclusion. > > It allows to do O_SYNC writes on a per-I/O basis. This is very useful > for file servers (smb, cifs) as well as storage target devices. This would be particularly useful for SMB3 as the protocol now allows write-through vs. no-write-through flag on every write request (not just on an open, it can be changed on a particular i/o to write-through). There is also a cache/no-cache hint that can be sent on reads/writes in the newest SMB3 dialect well (but it is less clear to me how we would ever decide to set that on the Linux client). -- Thanks, Steve -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org