[PATCH 12/28] VFS: Remove (now bogus) check_mnt

[Mike Waychison <michael.waychison@sun.com>]

check_mnt used to be used to see if a mountpoint was actually grafted or not
to a namespace.  This was done because we didn't support mountpoints being
attached to one another if they weren't associated with a namespace. We now
support this, so all check_mnt calls are bogus.  The only exception is that
pivot_root still requires all participants to exist within the same
namespace.

Signed-off-by: Mike Waychison <michael.waychison@sun.com>
---

 namespace.c |   41 +++++++++++------------------------------
 1 files changed, 11 insertions(+), 30 deletions(-)

Index: linux-2.6.9-quilt/fs/namespace.c
===================================================================
--- linux-2.6.9-quilt.orig/fs/namespace.c	2004-10-22 17:17:38.881553248 -0400
+++ linux-2.6.9-quilt/fs/namespace.c	2004-10-22 17:17:39.557450496 -0400
@@ -124,14 +124,8 @@ struct vfsmount *lookup_mnt(struct vfsmo
 	spin_unlock(&vfsmount_lock);
 	return found;
 }
-
 EXPORT_SYMBOL(lookup_mnt);
 
-static inline int check_mnt(struct vfsmount *mnt)
-{
-	return mnt->mnt_namespace == current->namespace;
-}
-
 static struct vfsmount *next_mnt(struct vfsmount *p, struct vfsmount *root)
 {
 	struct list_head *next = p->mnt_mounts.next;
@@ -701,8 +695,6 @@ asmlinkage long sys_umount(char __user *
 	retval = -EINVAL;
 	if (nd.dentry != nd.mnt->mnt_root)
 		goto dput_and_out;
-	if (!check_mnt(nd.mnt))
-		goto dput_and_out;
 
 	retval = -EPERM;
 	if (!capable(CAP_SYS_ADMIN))
@@ -867,14 +859,11 @@ static int do_loopback(struct nameidata 
 		return err;
 
 	down_write(&current->namespace->sem);
-	err = -EINVAL;
-	if (check_mnt(nd->mnt) && (!recurse || check_mnt(old_nd.mnt))) {
-		err = -ENOMEM;
-		if (recurse)
-			mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);
-		else
-			mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);
-	}
+	err = -ENOMEM;
+	if (recurse)
+		mnt = copy_tree(old_nd.mnt, old_nd.dentry, 0);
+	else
+		mnt = clone_mnt(old_nd.mnt, old_nd.dentry, 0);
 
 	if (mnt) {
 		/* stop bind mounts from expiring */
@@ -912,9 +901,6 @@ static int do_remount(struct nameidata *
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	if (!check_mnt(nd->mnt))
-		return -EINVAL;
-
 	if (nd->dentry != nd->mnt->mnt_root)
 		return -EINVAL;
 
@@ -945,9 +931,6 @@ static int do_move_mount(struct nameidat
 	down_write(&current->namespace->sem);
 	while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
 		;
-	err = -EINVAL;
-	if (!check_mnt(nd->mnt) || !check_mnt(old_nd.mnt))
-		goto out;
 
 	err = -ENOENT;
 	down(&nd->dentry->d_inode->i_sem);
@@ -984,7 +967,6 @@ out2:
 	spin_unlock(&vfsmount_lock);
 out1:
 	up(&nd->dentry->d_inode->i_sem);
-out:
 	up_write(&current->namespace->sem);
 	if (!err)
 		path_release(&parent_nd);
@@ -1028,9 +1010,6 @@ int do_graft_mount(struct vfsmount *newm
 	/* Something was mounted here while we slept */
 	while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
 		;
-	err = -EINVAL;
-	if (!check_mnt(nd->mnt))
-		goto unlock;
 
 	/* Refuse the same filesystem on the same mount point */
 	err = -EBUSY;
@@ -1569,9 +1548,6 @@ asmlinkage long sys_pivot_root(const cha
 	error = __user_walk(new_root, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &new_nd);
 	if (error)
 		goto out0;
-	error = -EINVAL;
-	if (!check_mnt(new_nd.mnt))
-		goto out1;
 
 	error = __user_walk(put_old, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &old_nd);
 	if (error)
@@ -1589,9 +1565,14 @@ asmlinkage long sys_pivot_root(const cha
 	read_unlock(&current->fs->lock);
 	down_write(&current->namespace->sem);
 	down(&old_nd.dentry->d_inode->i_sem);
+	
+	/* All mountpoints must exist within the same namespace */
 	error = -EINVAL;
-	if (!check_mnt(user_nd.mnt))
+	if (user_nd.mnt->mnt_namespace != current->namespace
+	 || user_nd.mnt->mnt_namespace != old_nd.mnt->mnt_namespace
+	 || user_nd.mnt->mnt_namespace != new_nd.mnt->mnt_namespace)
 		goto out2;
+
 	error = -ENOENT;
 	if (IS_DEADDIR(new_nd.dentry->d_inode))
 		goto out2;