From: Al Viro Subject: Re: [PATCH] ext2: Don't export ext2_mask_flags() to user space Date: Thu, 22 Mar 2012 17:31:50 +0000 Message-ID: <20120322173150.GY6589@ZenIV.linux.org.uk> References: <1332366608-2695-1-git-send-email-thierry.reding@avionic-design.de> <20120321222357.GB24330@quack.suse.cz> <20120321231651.GC32041@thunk.org> <20120322055354.GA3942@avionic-0098.mockup.avionic-design.de> <1332396053.3058.2.camel@koala> <20120322162825.GA4028@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Ted Ts'o , Artem Bityutskiy , Thierry Reding , Jan Kara , linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, stable@vger.kernel.org Return-path: Received: from zeniv.linux.org.uk ([195.92.253.2]:60697 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753408Ab2CVRb5 (ORCPT ); Thu, 22 Mar 2012 13:31:57 -0400 Content-Disposition: inline In-Reply-To: <20120322162825.GA4028@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Mar 22, 2012 at 12:28:25PM -0400, Ted Ts'o wrote: > On Thu, Mar 22, 2012 at 08:00:41AM +0200, Artem Bityutskiy wrote: > > On Thu, 2012-03-22 at 06:53 +0100, Thierry Reding wrote: > > > What's the recommended fix for packages that cannot or will not use > > > libext2fs, like busybox? Copy the required parts into a private header > > > and use that instead? > > > > The normal way is to just keep a private copy of the whole header file. > > Because the on-disk format stays compatible, those programs do not have > > to update the header very often - only rarely if they want to support > > some new feature. > > Even if they're not iwlling to use libext2fs (for space reasons, I > would assume? It can't be because of license compatibility issues > since they are both GPLv2), they could just simply grab the ext2_fs.h > from e2fsprogs. That has all of the file system definitions for ext2, > ext3, and ext4. Ho-hum... Then we could kill a lot of lines in include/linux/ext2_fs.h. I wonder how much of what remains has any business being outside of fs/ext2, actually - AFAICS, there are very few places that might possibly care: arch/blackfin/kernel/setup.c:595: if (*((unsigned short *)(mtd_phys + 0x438)) == EXT2_SUPER_MAGIC) fs/nfsd/nfs3proc.c:599: case EXT2_SUPER_MAGIC: fs/nfsd/nfs3proc.c:600: resp->p_link_max = EXT2_LINK_MAX; fs/nfsd/nfs3proc.c:601: resp->p_name_max = EXT2_NAME_LEN; init/do_mounts_rd.c:57: struct ext2_super_block *ext2sb; init/do_mounts_rd.c:70: ext2sb = (struct ext2_super_block *) buf; init/do_mounts_rd.c:153: if (ext2sb->s_magic == cpu_to_le16(EXT2_SUPER_MAGIC)) { init/do_mounts_rd.c:155: "RAMDISK: ext2 filesystem found at block %d\n", init/do_mounts_rd.c:157: nblocks = le32_to_cpu(ext2sb->s_blocks_count) << init/do_mounts_rd.c:158: le32_to_cpu(ext2sb->s_log_block_size); security/selinux/hooks.c:2974: case EXT2_IOC_GETFLAGS: security/selinux/hooks.c:2976: case EXT2_IOC_GETVERSION: security/selinux/hooks.c:2980: case EXT2_IOC_SETFLAGS: security/selinux/hooks.c:2982: case EXT2_IOC_SETVERSION: and that's it. blackfin and do_mounts_rd are doing the same thing (blackfin - buggy, AFAICS). Looks like both are asking for something along the lines of sector_t detect_ext2(void *image), returning 0 if it's not one and size in kilobytes if it is... nfsd one is just plain weird; what the hell is going on there? And selinux wants to know 4 ioctl numbers. Everything else doesn't go beyond fs/ext2; there's a couple of odd macros in ext[34]_fs.h (EXT._FEATURE_COMPAT_SUPP) using EXT2_FEATURE_COMPAT_EXT_ATTR, but they are not used anywhere *and* EXT2_FEATURE_COMPAT_EXT_ATTR is not available in the places that include those headers... *and*