From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 10 May 2002 00:02:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 10 May 2002 00:02:44 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:35079 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Fri, 10 May 2002 00:02:44 -0400 Message-ID: <3CDB4711.1A4FFDAC@zip.com.au> Date: Thu, 09 May 2002 21:05:37 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-pre4 i686) X-Accept-Language: en MIME-Version: 1.0 To: Peter Chubb CC: linux-kernel@vger.kernel.org, martin@dalecki.de, neilb@cse.unsw.edu.au Subject: Re: [PATCH] remove 2TB block device limit In-Reply-To: <15579.16423.930012.986750@wombat.chubb.wattle.id.au> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Peter Chubb wrote: > > Hi, > At present, linux is limited to 2TB filesystems even on 64-bit > systems, because there are various places where the block offset on > disc are assigned to unsigned or int 32-bit variables. > > There's a type, sector_t, that's meant to hold offsets in sectors and > blocks. It's not used consistently (yet). > > The patch at > http://www.gelato.unsw.edu.au/patches/2.5.14-largefile-patch > > ... > > As this touches lots of places -- the generic block layer (Andrew?) > the IDE code (Martin?) and RAID (Neil?) and minor changes to the scsi > I've CCd a few people directly. That would be more Jens and aviro than I. My vote would be: just merge the sucker while it still (almost) applies. 2TB is a showstopper for some people in 2.4 today. Obviously 2.6 will need 64-bit block numbers. The next obstacle will be page cache indices into the blockdev mapping. That's either an 8TB or 16TB limit, depending on signedness correctness. One minor point - it is currently not possible to print sector_t's. This code: printk("%lu%s", some_sector, some_string); will work fine with 32-bit sector_t. But with 64-bit sector_t it will generate a warning at compile-time and an oops at runtime. The same problem applies to dma_addr_t. Jeff, davem and I kicked that around a while back and ended up deciding that although there are a number of high-tech solutions, the dumb one was best: --- 2.5.14/include/linux/types.h~sector_t-printing Thu May 9 17:08:13 2002 +++ 2.5.14-akpm/include/linux/types.h Thu May 9 17:08:13 2002 @@ -120,8 +120,10 @@ typedef __s64 int64_t; #ifdef BLK_64BIT_SECTOR typedef u64 sector_t; +#define FMT_SECTOR_T "%Lu" #else typedef unsigned long sector_t; +#define FMT_SECTOR_T "%lu" #endif #endif /* __KERNEL_STRICT_NAMES */ --- 2.5.14/fs/buffer.c~sector_t-printing Thu May 9 17:08:13 2002 +++ 2.5.14-akpm/fs/buffer.c Thu May 9 17:09:35 2002 @@ -179,7 +179,8 @@ __clear_page_buffers(struct page *page) static void buffer_io_error(struct buffer_head *bh) { - printk(KERN_ERR "Buffer I/O error on device %s, logical block %ld\n", + printk(KERN_ERR "Buffer I/O error on device %s," + " logical block " FMT_SECTOR_T "\n", bdevname(bh->b_bdev), bh->b_blocknr); }