From: Dave Kleikamp Subject: Re: [RFC] Heads up on sys_fallocate() Date: Thu, 01 Mar 2007 22:44:16 +0000 Message-ID: <1172789056.11165.42.camel@kleikamp.austin.ibm.com> References: <20070117094658.GA17390@amitarora.in.ibm.com> <20070225022326.137b4875.akpm@linux-foundation.org> <20070301183445.GA7911@amitarora.in.ibm.com> <20070301142537.b5950cd7.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: "Amit K. Arora" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, suparna@in.ibm.com, cmm@us.ibm.com, alex@clusterfs.com, suzuki@in.ibm.com, Ulrich Drepper To: Andrew Morton Return-path: Received: from e5.ny.us.ibm.com ([32.97.182.145]:36611 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161043AbXCAWoT (ORCPT ); Thu, 1 Mar 2007 17:44:19 -0500 In-Reply-To: <20070301142537.b5950cd7.akpm@linux-foundation.org> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, 2007-03-01 at 14:25 -0800, Andrew Morton wrote: > On Fri, 2 Mar 2007 00:04:45 +0530 > "Amit K. Arora" wrote: > > +asmlinkage long sys_fallocate(int fd, loff_t offset, loff_t len) > > +{ > > + struct file *file; > > + struct inode *inode; > > + long ret = -EINVAL; > > + file = fget(fd); > > + if (!file) > > + goto out; > > + inode = file->f_path.dentry->d_inode; > > + if (inode->i_op && inode->i_op->fallocate) > > + ret = inode->i_op->fallocate(inode, offset, len); > > + else > > + ret = -ENOTTY; > > + fput(file); > > +out: > > + return ret; > > +} > > ENOTTY is a bit unconventional - we often use EINVAL for this sort of > thing. But EINVAL has other meanings for posix_fallocate() and isn't > really appropriate here anyway. So I'm not sure what would be better... Would EINVAL (or whatever) make it back to the caller of posix_fallocate(), or would glibc fall back to its current implementation? Forgive me if I haven't put enough thought into it, but would it be useful to create a generic_fallocate() that writes zeroed pages for any non-existent pages in the range? I don't know how glibc currently implements posix_fallocate(), but maybe the kernel could do it more efficiently, even in generic code. Maybe we don't care, since the major file systems can probably do something better in their own code. -- David Kleikamp IBM Linux Technology Center