[PATCH] kill altroot

long overdue...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -31,7 +31,6 @@
 #include <linux/file.h>
 #include <linux/fcntl.h>
 #include <linux/device_cgroup.h>
-#include <asm/namei.h>
 #include <asm/uaccess.h>
 
 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
@@ -562,27 +561,16 @@ static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, s
 	return result;
 }
 
-static int __emul_lookup_dentry(const char *, struct nameidata *);
-
 /* SMP-safe */
-static __always_inline int
+static __always_inline void
 walk_init_root(const char *name, struct nameidata *nd)
 {
 	struct fs_struct *fs = current->fs;
 
 	read_lock(&fs->lock);
-	if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) {
-		nd->path = fs->altroot;
-		path_get(&fs->altroot);
-		read_unlock(&fs->lock);
-		if (__emul_lookup_dentry(name,nd))
-			return 0;
-		read_lock(&fs->lock);
-	}
 	nd->path = fs->root;
 	path_get(&fs->root);
 	read_unlock(&fs->lock);
-	return 1;
 }
 
 /*
@@ -623,12 +611,9 @@ static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *l
 
 	if (*link == '/') {
 		path_put(&nd->path);
-		if (!walk_init_root(link, nd))
-			/* weird __emul_prefix() stuff did it */
-			goto out;
+		walk_init_root(link, nd);
 	}
 	res = link_path_walk(link, nd);
-out:
 	if (nd->depth || res || nd->last_type!=LAST_NORM)
 		return res;
 	/*
@@ -1077,67 +1062,6 @@ static int path_walk(const char *name, struct nameidata *nd)
 	return link_path_walk(name, nd);
 }
 
-/* 
- * SMP-safe: Returns 1 and nd will have valid dentry and mnt, if
- * everything is done. Returns 0 and drops input nd, if lookup failed;
- */
-static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
-{
-	if (path_walk(name, nd))
-		return 0;		/* something went wrong... */
-
-	if (!nd->path.dentry->d_inode ||
-	    S_ISDIR(nd->path.dentry->d_inode->i_mode)) {
-		struct path old_path = nd->path;
-		struct qstr last = nd->last;
-		int last_type = nd->last_type;
-		struct fs_struct *fs = current->fs;
-
-		/*
-		 * NAME was not found in alternate root or it's a directory.
-		 * Try to find it in the normal root:
-		 */
-		nd->last_type = LAST_ROOT;
-		read_lock(&fs->lock);
-		nd->path = fs->root;
-		path_get(&fs->root);
-		read_unlock(&fs->lock);
-		if (path_walk(name, nd) == 0) {
-			if (nd->path.dentry->d_inode) {
-				path_put(&old_path);
-				return 1;
-			}
-			path_put(&nd->path);
-		}
-		nd->path = old_path;
-		nd->last = last;
-		nd->last_type = last_type;
-	}
-	return 1;
-}
-
-void set_fs_altroot(void)
-{
-	char *emul = __emul_prefix();
-	struct nameidata nd;
-	struct path path = {}, old_path;
-	int err;
-	struct fs_struct *fs = current->fs;
-
-	if (!emul)
-		goto set_it;
-	err = path_lookup(emul, LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_NOALT, &nd);
-	if (!err)
-		path = nd.path;
-set_it:
-	write_lock(&fs->lock);
-	old_path = fs->altroot;
-	fs->altroot = path;
-	write_unlock(&fs->lock);
-	if (old_path.dentry)
-		path_put(&old_path);
-}
-
 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
 static int do_path_lookup(int dfd, const char *name,
 				unsigned int flags, struct nameidata *nd)
@@ -1153,14 +1077,6 @@ static int do_path_lookup(int dfd, const char *name,
 
 	if (*name=='/') {
 		read_lock(&fs->lock);
-		if (fs->altroot.dentry && !(nd->flags & LOOKUP_NOALT)) {
-			nd->path = fs->altroot;
-			path_get(&fs->altroot);
-			read_unlock(&fs->lock);
-			if (__emul_lookup_dentry(name,nd))
-				goto out; /* found in altroot */
-			read_lock(&fs->lock);
-		}
 		nd->path = fs->root;
 		path_get(&fs->root);
 		read_unlock(&fs->lock);
@@ -1194,7 +1110,6 @@ static int do_path_lookup(int dfd, const char *name,
 	}
 
 	retval = path_walk(name, nd);
-out:
 	if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
 				nd->path.dentry->d_inode))
 		audit_inode(name, nd->path.dentry);

fs/namespace.c

@@ -1972,7 +1972,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
 		struct fs_struct *fs)
 {
 	struct mnt_namespace *new_ns;
-	struct vfsmount *rootmnt = NULL, *pwdmnt = NULL, *altrootmnt = NULL;
+	struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
 	struct vfsmount *p, *q;
 
 	new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
@@ -2015,10 +2015,6 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
 				pwdmnt = p;
 				fs->pwd.mnt = mntget(q);
 			}
-			if (p == fs->altroot.mnt) {
-				altrootmnt = p;
-				fs->altroot.mnt = mntget(q);
-			}
 		}
 		p = next_mnt(p, mnt_ns->root);
 		q = next_mnt(q, new_ns->root);
@@ -2029,8 +2025,6 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
 		mntput(rootmnt);
 	if (pwdmnt)
 		mntput(pwdmnt);
-	if (altrootmnt)
-		mntput(altrootmnt);
 
 	return new_ns;
 }

fs/open.c

@@ -548,7 +548,7 @@ asmlinkage long sys_chroot(const char __user * filename)
 	struct nameidata nd;
 	int error;
 
-	error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
+	error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &nd);
 	if (error)
 		goto out;
 
@@ -561,7 +561,6 @@ asmlinkage long sys_chroot(const char __user * filename)
 		goto dput_and_out;
 
 	set_fs_root(current->fs, &nd.path);
-	set_fs_altroot();
 	error = 0;
 dput_and_out:
 	path_put(&nd.path);

include/asm-alpha/namei.h

-/* $Id: namei.h,v 1.1 1996/12/13 14:48:21 jj Exp $
- * linux/include/asm-alpha/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __ALPHA_NAMEI_H
-#define __ALPHA_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* __ALPHA_NAMEI_H */

include/asm-arm/namei.h

-/* 
- * linux/include/asm-arm/namei.h
- *
- * Routines to handle famous /usr/gnemul
- * Derived from the Sparc version of this file
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __ASMARM_NAMEI_H
-#define __ASMARM_NAMEI_H
-
-#define ARM_BSD_EMUL "usr/gnemul/bsd/"
-
-static inline char *__emul_prefix(void)
-{
-	switch (current->personality) {
-	case PER_BSD:
-		return ARM_BSD_EMUL;
-	default:
-		return NULL;
-	}
-}
-
-#endif /* __ASMARM_NAMEI_H */

include/asm-avr32/namei.h

-#ifndef __ASM_AVR32_NAMEI_H
-#define __ASM_AVR32_NAMEI_H
-
-/* This dummy routine may be changed to something useful */
-#define __emul_prefix() NULL
-
-#endif /* __ASM_AVR32_NAMEI_H */

include/asm-blackfin/namei.h

-/*
- * linux/include/asm/namei.h
- *
- * Included from linux/fs/namei.c
- *
- * Changes made by Lineo Inc.    May 2001
- */
-
-#ifndef __BFIN_NAMEI_H
-#define __BFIN_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif

include/asm-cris/namei.h

-/* $Id: namei.h,v 1.1 2000/07/10 16:32:31 bjornw Exp $
- * linux/include/asm-cris/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __CRIS_NAMEI_H
-#define __CRIS_NAMEI_H
-
-/* used to find file-system prefixes for doing emulations
- * see for example asm-sparc/namei.h
- * we don't use it...
- */
-
-#define __emul_prefix() NULL
-
-#endif /* __CRIS_NAMEI_H */

include/asm-frv/namei.h

-/*
- * include/asm-frv/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __ASM_NAMEI_H
-#define __ASM_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif
-

include/asm-h8300/namei.h

-/*
- * linux/include/asm-h8300/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __H8300_NAMEI_H
-#define __H8300_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif

include/asm-ia64/namei.h

-#ifndef _ASM_IA64_NAMEI_H
-#define _ASM_IA64_NAMEI_H
-
-/*
- * Modified 1998, 1999, 2001
- *	David Mosberger-Tang <davidm@hpl.hp.com>, Hewlett-Packard Co
- */
-
-#include <asm/ptrace.h>
-#include <asm/system.h>
-
-#define EMUL_PREFIX_LINUX_IA32 "/emul/ia32-linux/"
-
-static inline char *
-__emul_prefix (void)
-{
-	switch (current->personality) {
-	      case PER_LINUX32:
-		return EMUL_PREFIX_LINUX_IA32;
-	      default:
-		return NULL;
-	}
-}
-
-#endif /* _ASM_IA64_NAMEI_H */

include/asm-m32r/namei.h

-#ifndef _ASM_M32R_NAMEI_H
-#define _ASM_M32R_NAMEI_H
-
-/*
- * linux/include/asm-m32r/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* _ASM_M32R_NAMEI_H */

include/asm-m68k/namei.h

-/*
- * linux/include/asm-m68k/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __M68K_NAMEI_H
-#define __M68K_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif

include/asm-m68knommu/namei.h

-#include <asm-m68k/namei.h>

include/asm-mips/namei.h

-#ifndef _ASM_NAMEI_H
-#define _ASM_NAMEI_H
-
-/*
- * This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* _ASM_NAMEI_H */

include/asm-mn10300/namei.h

-/* Emulation stuff
- *
- * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public Licence
- * as published by the Free Software Foundation; either version
- * 2 of the Licence, or (at your option) any later version.
- */
-
-#ifndef _ASM_NAMEI_H
-#define _ASM_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* _ASM_NAMEI_H */

include/asm-parisc/namei.h

-/* $Id: namei.h,v 1.1 1996/12/13 14:48:21 jj Exp $
- * linux/include/asm-parisc/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __PARISC_NAMEI_H
-#define __PARISC_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* __PARISC_NAMEI_H */

include/asm-powerpc/namei.h

-#ifndef _ASM_POWERPC_NAMEI_H
-#define _ASM_POWERPC_NAMEI_H
-
-#ifdef __KERNEL__
-
-/*
- * Adapted from include/asm-alpha/namei.h
- *
- * Included from fs/namei.c
- */
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif	/* __KERNEL__ */
-#endif	/* _ASM_POWERPC_NAMEI_H */

include/asm-s390/namei.h

-/*
- *  include/asm-s390/namei.h
- *
- *  S390 version
- *
- *  Derived from "include/asm-i386/namei.h"
- *
- *  Included from linux/fs/namei.c
- */
-
-#ifndef __S390_NAMEI_H
-#define __S390_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* __S390_NAMEI_H */

include/asm-sh/namei.h

-/* $Id: namei.h,v 1.3 2000/07/04 06:24:49 gniibe Exp $
- * linux/include/asm-sh/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __ASM_SH_NAMEI_H
-#define __ASM_SH_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* __ASM_SH_NAMEI_H */

include/asm-sparc/namei.h

-#ifndef ___ASM_SPARC_NAMEI_H
-#define ___ASM_SPARC_NAMEI_H
-#if defined(__sparc__) && defined(__arch64__)
-#include <asm-sparc/namei_64.h>
-#else
-#include <asm-sparc/namei_32.h>
-#endif
-#endif

include/asm-sparc64/namei.h

-#include <asm-sparc/namei.h>

include/asm-um/namei.h

-#ifndef __UM_NAMEI_H
-#define __UM_NAMEI_H
-
-#include "asm/arch/namei.h"
-
-#endif

include/asm-v850/namei.h

-/*
- * linux/include/asm-v850/namei.h
- *
- * Included from linux/fs/namei.c
- */
-
-#ifndef __V850_NAMEI_H__
-#define __V850_NAMEI_H__
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* __V850_NAMEI_H__ */

include/asm-x86/namei.h

-#ifndef _ASM_X86_NAMEI_H
-#define _ASM_X86_NAMEI_H
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif /* _ASM_X86_NAMEI_H */

include/asm-xtensa/namei.h

-/*
- * include/asm-xtensa/namei.h
- *
- * Included from linux/fs/namei.c
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 2001 - 2005 Tensilica Inc.
- */
-
-#ifndef _XTENSA_NAMEI_H
-#define _XTENSA_NAMEI_H
-
-#ifdef __KERNEL__
-
-/* This dummy routine maybe changed to something useful
- * for /usr/gnemul/ emulation stuff.
- * Look at asm-sparc/namei.h for details.
- */
-
-#define __emul_prefix() NULL
-
-#endif	/* __KERNEL__ */
-#endif	/* _XTENSA_NAMEI_H */

include/linux/fs_struct.h

@@ -7,7 +7,7 @@ struct fs_struct {
 	atomic_t count;
 	rwlock_t lock;
 	int umask;
-	struct path root, pwd, altroot;
+	struct path root, pwd;
 };
 
 #define INIT_FS {				\
@@ -19,7 +19,6 @@ struct fs_struct {
 extern struct kmem_cache *fs_cachep;
 
 extern void exit_fs(struct task_struct *);
-extern void set_fs_altroot(void);
 extern void set_fs_root(struct fs_struct *, struct path *);
 extern void set_fs_pwd(struct fs_struct *, struct path *);
 extern struct fs_struct *copy_fs_struct(struct fs_struct *);

include/linux/namei.h

@@ -47,7 +47,6 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
 #define LOOKUP_DIRECTORY	 2
 #define LOOKUP_CONTINUE		 4
 #define LOOKUP_PARENT		16
-#define LOOKUP_NOALT		32
 #define LOOKUP_REVAL		64
 /*
  * Intent data

kernel/exec_domain.c

@@ -168,7 +168,6 @@ __set_personality(u_long personality)
 	current->personality = personality;
 	oep = current_thread_info()->exec_domain;
 	current_thread_info()->exec_domain = ep;
-	set_fs_altroot();
 
 	module_put(oep->module);
 	return 0;

kernel/exit.c

@@ -565,8 +565,6 @@ void put_fs_struct(struct fs_struct *fs)
 	if (atomic_dec_and_test(&fs->count)) {
 		path_put(&fs->root);
 		path_put(&fs->pwd);
-		if (fs->altroot.dentry)
-			path_put(&fs->altroot);
 		kmem_cache_free(fs_cachep, fs);
 	}
 }

kernel/fork.c

@@ -657,13 +657,6 @@ static struct fs_struct *__copy_fs_struct(struct fs_struct *old)
 		path_get(&old->root);
 		fs->pwd = old->pwd;
 		path_get(&old->pwd);
-		if (old->altroot.dentry) {
-			fs->altroot = old->altroot;
-			path_get(&old->altroot);
-		} else {
-			fs->altroot.mnt = NULL;
-			fs->altroot.dentry = NULL;
-		}
 		read_unlock(&old->lock);
 	}
 	return fs;