From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: [RFC] Heads up on sys_fallocate() Date: Mon, 5 Mar 2007 16:33:27 +0100 Message-ID: <20070305153326.GA1469@lazybastard.org> References: <20070117094658.GA17390@amitarora.in.ibm.com> <45EB4A55.3060908@redhat.com> <20070305001621.GB18691@lazybastard.org> <200703050136.37181.arnd@arndb.de> <20070305114109.GA454@lazybastard.org> <45EC3253.2030206@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Arnd Bergmann , Christoph Hellwig , Dave Kleikamp , Andrew Morton , "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 To: Ulrich Drepper Return-path: Content-Disposition: inline In-Reply-To: <45EC3253.2030206@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, 5 March 2007 07:08:03 -0800, Ulrich Drepper wrote: > J=C3=B6rn Engel wrote: > > Does the allocation have to be persistent beyond lifetime of the fi= le > > descriptor? >=20 > Of course. You call posix_fallocate once for the lifetime of the fil= e > when it is created to ensure that all future uses will work. That part is not quite clear from the manpage but I trust most people would assume the same. > It seems your filesystem will not be able to support this unless > compression is turned off. Correct. Compression needs to be turned off for a file, if posix_fallocate(3) is to succeed. What I could do is disable compression (meaning that no data written in the future will be compressed) and rewrite all blocks within the given range. Still, it is quite obvious that noone designing this interface has lost much thought to compressing filesystems. Whatever I can come up with will either be incompatible or some sort of hack. :( J=C3=B6rn --=20 Courage is not the absence of fear, but rather the judgement that something else is more important than fear. -- Ambrose Redmoon - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html