From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: How to handle >16TB devices on 32 bit hosts ?? Date: Wed, 22 Jul 2009 11:51:55 -0700 Message-ID: <20090722115155.f99dcf76.akpm@linux-foundation.org> References: <19041.4714.686158.130252@notabene.brown> <20090721235904.42e6cd35.akpm@linux-foundation.org> <20090722183244.GO4231@webber.adilger.int> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org To: Andreas Dilger Return-path: In-Reply-To: <20090722183244.GO4231@webber.adilger.int> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com List-Id: linux-fsdevel.vger.kernel.org On Wed, 22 Jul 2009 12:32:44 -0600 Andreas Dilger wrote: > On Jul 21, 2009 23:59 -0700, Andrew Morton wrote: > > On Sat, 18 Jul 2009 10:08:10 +1000 Neil Brown wrote: > > I expect that the VFS could be made to work with 64-bit pgoff_t fairly > > easily. The generated code will be pretty damn sad. > > > > radix-trees use a ulong index, so we would need a new > > lib/radix_tree64.c or some other means of fixing that up. > > > > The bigger problem is filesystems - they'll each need to be checked, > > tested, fixed and enabled. It's probably not too bad for the > > mainstream filesystems which mostly bounce their operations into VFS > > libarary functions anyway. > > I don't think this is a primary concern for most filesystems even today. > Filesystems that work correctly > 16TB on 64-bit platforms should continue > to work correctly on 32-bit platforms. Not if they use an unsigned long to hold a pagecache index anywhere. akpm:/usr/src/25> grep 'unsigned long' fs/*/*.c | wc -l 3465