[PATCH] umount after bad chdir

[Hugh Dickins]

After chdir (or chroot) to non-existent directory on 2.6.5-mm5, you
can no longer unmount filesystem holding working directory (or root).

--- 2.6.5-mm5/fs/open.c	2004-04-13 11:02:25.000000000 +0100
+++ linux/fs/open.c	2004-04-14 12:23:26.633056368 +0100
@@ -517,13 +517,16 @@ asmlinkage long sys_chdir(const char __u
 {
 	struct nameidata nd;
 	int error;
-	struct vfsmount *old_mnt = mntget(current->fs->pwdmnt);
-	struct dentry *old_dentry = dget(current->fs->pwd);
+	struct vfsmount *old_mnt;
+	struct dentry *old_dentry;
 
 	error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
 	if (error)
 		goto out;
 
+	old_mnt = mntget(current->fs->pwdmnt);
+	old_dentry = dget(current->fs->pwd);
+
 	error = permission(nd.dentry->d_inode,MAY_EXEC,&nd);
 	if (error)
 		goto dput_and_out;
@@ -590,13 +593,16 @@ asmlinkage long sys_chroot(const char __
 {
 	struct nameidata nd;
 	int error;
-	struct vfsmount *old_mnt = mntget(current->fs->rootmnt);
-	struct dentry *old_dentry = dget(current->fs->root);
+	struct vfsmount *old_mnt;
+	struct dentry *old_dentry;
 
 	error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
 	if (error)
 		goto out;
 
+	old_mnt = mntget(current->fs->pwdmnt);
+	old_dentry = dget(current->fs->pwd);
+
 	error = permission(nd.dentry->d_inode,MAY_EXEC,&nd);
 	if (error)
 		goto dput_and_out;

-
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