From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Fri, 30 Mar 2007 00:19:44 -0700 (PDT) Received: from mtagate7.de.ibm.com (mtagate7.de.ibm.com [195.212.29.156]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id l2U7Ja6p018351 for ; Fri, 30 Mar 2007 00:19:37 -0700 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate7.de.ibm.com (8.13.8/8.13.8) with ESMTP id l2U7JUdW131392 for ; Fri, 30 Mar 2007 07:19:30 GMT Received: from d12av04.megacenter.de.ibm.com (d12av04.megacenter.de.ibm.com [9.149.165.229]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v8.3) with ESMTP id l2U7JUCX1917088 for ; Fri, 30 Mar 2007 09:19:30 +0200 Received: from d12av04.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av04.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id l2U7JTNx030448 for ; Fri, 30 Mar 2007 09:19:30 +0200 Date: Fri, 30 Mar 2007 09:19:29 +0200 From: Heiko Carstens Subject: Re: Interface for the new fallocate() system call Message-ID: <20070330071929.GC8365@osiris.boeblingen.de.ibm.com> References: <20070117094658.GA17390@amitarora.in.ibm.com> <20070225022326.137b4875.akpm@linux-foundation.org> <20070301183445.GA7911@amitarora.in.ibm.com> <20070316143101.GA10152@amitarora.in.ibm.com> <20070316161704.GE8525@osiris.boeblingen.de.ibm.com> <20070317111036.GC29931@parisc-linux.org> <20070321120425.GA27273@amitarora.in.ibm.com> <20070329115126.GB7374@amitarora.in.ibm.com> <20070329101010.7a2b8783.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070329101010.7a2b8783.akpm@linux-foundation.org> Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Andrew Morton Cc: "Amit K. Arora" , torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, xfs@oss.sgi.com, suparna@in.ibm.com, cmm@us.ibm.com > > Even ARM prefers above kind of layout. For details please see the > > definition of sys_arm_sync_file_range(). > > This is a clean-looking option. Can s390 be changed to support seven-arg > syscalls? > > > Option of loff_t => high u32 + low u32 > > -------------------------------------- > > Matthew and Russell have suggested another option of breaking each > > "loff_t" into two "u32"s. This will result in 6 arguments in total. > > > > Following think that this is a good alternative: > > Matthew Wilcox, Russell King, Heiko Carstens > > > > Following do not like this idea: > > Chris Wedgwood > > It's a bit weird-looking, but the six-32-bit-args approach is simple > enought to understand and implement. Presumably the glibc wrapper > would hide that detail from everyone. s390 can be changed to support seven-arg syscalls. But that would require creating an additional stackframe in *libc to save original register contents and in addition it would make our syscall hotpath slower. That is because we have to take care of an additional register that might contain user space passed contents and needs to be put on the kernel stack. If possible I'd prefer the six-32-bit-args approach.