From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752864AbXLDLVS (ORCPT ); Tue, 4 Dec 2007 06:21:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752290AbXLDLVF (ORCPT ); Tue, 4 Dec 2007 06:21:05 -0500 Received: from cantor2.suse.de ([195.135.220.15]:33236 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752247AbXLDLVD (ORCPT ); Tue, 4 Dec 2007 06:21:03 -0500 Date: Tue, 4 Dec 2007 12:21:00 +0100 From: Nick Piggin To: Christian Borntraeger Cc: Linux Kernel Mailing List , linux-fsdevel@vger.kernel.org, "Eric W. Biederman" , Andrew Morton , rob@landley.net, Jens Axboe Subject: [patch] rd: support XIP Message-ID: <20071204112100.GA20420@wotan.suse.de> References: <20071204042628.GA26636@wotan.suse.de> <200712041054.51599.borntraeger@de.ibm.com> <20071204101009.GB9618@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071204101009.GB9618@wotan.suse.de> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 04, 2007 at 11:10:09AM +0100, Nick Piggin wrote: > > > > This is just an idea, I dont know if it is worth the trouble, but have you > > though about implementing direct_access for brd? That would allow > > execute-in-place (xip) on brd eliminating the extra copy. > > Actually that's a pretty good idea. It would allow xip to be tested > without special hardware as well... > > I'll see what the patch looks like. Thanks This seems to work, although I needed another patch for ext2 too. Never run XIP before, but I'm able to execute files out of the -oxip mount, so I'm guessing it's working ;) --- Support direct_access XIP method with brd. Signed-off-by: Nick Piggin --- Index: linux-2.6/drivers/block/Kconfig =================================================================== --- linux-2.6.orig/drivers/block/Kconfig +++ linux-2.6/drivers/block/Kconfig @@ -346,6 +346,16 @@ config BLK_DEV_RAM_SIZE The default value is 4096 kilobytes. Only change this if you know what you are doing. +config BLK_DEV_XIP + bool "Support XIP filesystems on RAM block device" + depends on BLK_DEV_RAM + default n + help + Support XIP filesystems (such as ext2 with XIP support on) on + top of block ram device. This will slightly enlarge the kernel, and + will prevent RAM block device backing store memory from being + allocated from highmem (only a problem for highmem systems). + config CDROM_PKTCDVD tristate "Packet writing on CD/DVD media" depends on !UML Index: linux-2.6/drivers/block/brd.c =================================================================== --- linux-2.6.orig/drivers/block/brd.c +++ linux-2.6/drivers/block/brd.c @@ -89,6 +89,7 @@ static struct page *brd_insert_page(stru { pgoff_t idx; struct page *page; + gfp_t gfp_flags; page = brd_lookup_page(brd, sector); if (page) @@ -97,7 +98,16 @@ static struct page *brd_insert_page(stru /* * Must use NOIO because we don't want to recurse back into the * block or filesystem layers from page reclaim. + * + * Cannot support XIP and highmem, because our ->direct_access + * routine for XIP must return memory that is always addressable. + * If XIP was reworked to use pfns and kmap throughout, this + * restriction might be able to be lifted. */ + gfp_flags = GFP_NOIO | __GFP_ZERO; +#ifndef CONFIG_BLK_DEV_XIP + gfp_flags |= __GFP_HIGHMEM; +#endif page = alloc_page(GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO); if (!page) return NULL; @@ -307,6 +317,28 @@ out: return 0; } +#ifdef CONFIG_BLK_DEV_XIP +static int brd_direct_access (struct block_device *bdev, sector_t sector, + unsigned long *data) +{ + struct brd_device *brd = bdev->bd_disk->private_data; + struct page *page; + + if (!brd) + return -ENODEV; + if (sector & (PAGE_SECTORS-1)) + return -EINVAL; + if (sector + PAGE_SECTORS > get_capacity(bdev->bd_disk)) + return -ERANGE; + page = brd_insert_page(brd, sector); + if (!page) + return -ENOMEM; + *data = (unsigned long)page_address(page); + + return 0; +} +#endif + static int brd_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg) { @@ -342,8 +374,11 @@ static int brd_ioctl(struct inode *inode } static struct block_device_operations brd_fops = { - .owner = THIS_MODULE, - .ioctl = brd_ioctl, + .owner = THIS_MODULE, + .ioctl = brd_ioctl, +#ifdef CONFIG_BLK_DEV_XIP + .direct_access = brd_direct_access, +#endif }; /*