From: Christoph Hellwig Subject: Re: [PATCH 2/6][TAKE7] fallocate() implementation in i386, x86_64 and powerpc Date: Fri, 13 Jul 2007 14:21:19 +0100 Message-ID: <20070713132118.GA23256@infradead.org> References: <20070713123816.GA18000@amitarora.in.ibm.com> <20070713124755.GB22961@amitarora.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, xfs@oss.sgi.com, tytso@mit.edu, cmm@us.ibm.com, suparna@in.ibm.com, adilger@clusterfs.com, dgc@sgi.com To: "Amit K. Arora" Return-path: Content-Disposition: inline In-Reply-To: <20070713124755.GB22961@amitarora.in.ibm.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Fri, Jul 13, 2007 at 06:17:55PM +0530, Amit K. Arora wrote: > /* > + * sys_fallocate - preallocate blocks or free preallocated blocks > + * @fd: the file descriptor > + * @mode: mode specifies the behavior of allocation. > + * @offset: The offset within file, from where allocation is being > + * requested. It should not have a negative value. > + * @len: The amount of space in bytes to be allocated, from the offset. > + * This can not be zero or a negative value. kerneldoc comments are for in-kernel APIs which syscalls aren't. I'd say just temove this comment, the manpage is a much better documentation anyway. > + * Generic fallocate to be added for file systems that do not > + * support fallocate. Please remove the comment, adding a generic fallback in kernelspace is a very dumb idea as we already discussed long time ago. > --- linux-2.6.22.orig/include/linux/fs.h > +++ linux-2.6.22/include/linux/fs.h > @@ -266,6 +266,21 @@ extern int dir_notify_enable; > #define SYNC_FILE_RANGE_WRITE 2 > #define SYNC_FILE_RANGE_WAIT_AFTER 4 > > +/* > + * sys_fallocate modes > + * Currently sys_fallocate supports two modes: > + * FALLOC_ALLOCATE : This is the preallocate mode, using which an application > + * may request reservation of space for a particular file. > + * The file size will be changed if the allocation is > + * beyond EOF. > + * FALLOC_RESV_SPACE : This is same as the above mode, with only one difference > + * that the file size will not be modified. > + */ > +#define FALLOC_FL_KEEP_SIZE 0x01 /* default is extend/shrink size */ > + > +#define FALLOC_ALLOCATE 0 > +#define FALLOC_RESV_SPACE FALLOC_FL_KEEP_SIZE Just remove FALLOC_ALLOCATE, 0 flags should be the default. I'm also not sure there is any point in having two namespace now that we have a flags- based ABI. Also please don't add this to fs.h. fs.h is a complete mess and the falloc flags are a new user ABI. Add a linux/falloc.h instead which can be added to headers-y so the ABI constant can be exported to userspace.