[PATCH] get rid of more nameidata passing in namespace.c

Further reduction of stack footprint (sys_pivot_root());
lose useless BKL in there, while we are at it.

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

1 files changed, 25 insertions, 28 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 87d2d82010bb..1bf302d0478b 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1205,32 +1205,32 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
         return 0;
 }
 
-static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
+static int graft_tree(struct vfsmount *mnt, struct path *path)
 {
         int err;
         if (mnt->mnt_sb->s_flags & MS_NOUSER)
                 return -EINVAL;
 
-        if (S_ISDIR(nd->path.dentry->d_inode->i_mode) !=
+        if (S_ISDIR(path->dentry->d_inode->i_mode) !=
               S_ISDIR(mnt->mnt_root->d_inode->i_mode))
                 return -ENOTDIR;
 
         err = -ENOENT;
-        mutex_lock(&nd->path.dentry->d_inode->i_mutex);
-        if (IS_DEADDIR(nd->path.dentry->d_inode))
+        mutex_lock(&path->dentry->d_inode->i_mutex);
+        if (IS_DEADDIR(path->dentry->d_inode))
                 goto out_unlock;
 
-        err = security_sb_check_sb(mnt, &nd->path);
+        err = security_sb_check_sb(mnt, path);
         if (err)
                 goto out_unlock;
 
         err = -ENOENT;
-        if (IS_ROOT(nd->path.dentry) || !d_unhashed(nd->path.dentry))
-                err = attach_recursive_mnt(mnt, &nd->path, NULL);
+        if (IS_ROOT(path->dentry) || !d_unhashed(path->dentry))
+                err = attach_recursive_mnt(mnt, path, NULL);
 out_unlock:
-        mutex_unlock(&nd->path.dentry->d_inode->i_mutex);
+        mutex_unlock(&path->dentry->d_inode->i_mutex);
         if (!err)
-                security_sb_post_addmount(mnt, &nd->path);
+                security_sb_post_addmount(mnt, path);
         return err;
 }
 
@@ -1294,7 +1294,7 @@ static noinline int do_loopback(struct nameidata *nd, char *old_name,
         if (!mnt)
                 goto out;
 
-        err = graft_tree(mnt, nd);
+        err = graft_tree(mnt, &nd->path);
         if (err) {
                 LIST_HEAD(umount_list);
                 spin_lock(&vfsmount_lock);
@@ -1501,7 +1501,7 @@ int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
                 goto unlock;
 
         newmnt->mnt_flags = mnt_flags;
-        if ((err = graft_tree(newmnt, nd)))
+        if ((err = graft_tree(newmnt, &nd->path)))
                 goto unlock;
 
         if (fslist) /* add to the specified expiration list */
@@ -1987,15 +1987,13 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
                                const char __user * put_old)
 {
         struct vfsmount *tmp;
-        struct nameidata new_nd, old_nd, user_nd;
-        struct path parent_path, root_parent;
+        struct nameidata new_nd, old_nd;
+        struct path parent_path, root_parent, root;
         int error;
 
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        lock_kernel();
-
         error = __user_walk(new_root, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
                             &new_nd);
         if (error)
@@ -2015,7 +2013,7 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
         }
 
         read_lock(&current->fs->lock);
-        user_nd.path = current->fs->root;
+        root = current->fs->root;
         path_get(&current->fs->root);
         read_unlock(&current->fs->lock);
         down_write(&namespace_sem);
@@ -2023,9 +2021,9 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
         error = -EINVAL;
         if (IS_MNT_SHARED(old_nd.path.mnt) ||
                 IS_MNT_SHARED(new_nd.path.mnt->mnt_parent) ||
-                IS_MNT_SHARED(user_nd.path.mnt->mnt_parent))
+                IS_MNT_SHARED(root.mnt->mnt_parent))
                 goto out2;
-        if (!check_mnt(user_nd.path.mnt))
+        if (!check_mnt(root.mnt))
                 goto out2;
         error = -ENOENT;
         if (IS_DEADDIR(new_nd.path.dentry->d_inode))
@@ -2035,13 +2033,13 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
         if (d_unhashed(old_nd.path.dentry) && !IS_ROOT(old_nd.path.dentry))
                 goto out2;
         error = -EBUSY;
-        if (new_nd.path.mnt == user_nd.path.mnt ||
-            old_nd.path.mnt == user_nd.path.mnt)
+        if (new_nd.path.mnt == root.mnt ||
+            old_nd.path.mnt == root.mnt)
                 goto out2; /* loop, on the same file system  */
         error = -EINVAL;
-        if (user_nd.path.mnt->mnt_root != user_nd.path.dentry)
+        if (root.mnt->mnt_root != root.dentry)
                 goto out2; /* not a mountpoint */
-        if (user_nd.path.mnt->mnt_parent == user_nd.path.mnt)
+        if (root.mnt->mnt_parent == root.mnt)
                 goto out2; /* not attached */
         if (new_nd.path.mnt->mnt_root != new_nd.path.dentry)
                 goto out2; /* not a mountpoint */
@@ -2063,27 +2061,26 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
         } else if (!is_subdir(old_nd.path.dentry, new_nd.path.dentry))
                 goto out3;
         detach_mnt(new_nd.path.mnt, &parent_path);
-        detach_mnt(user_nd.path.mnt, &root_parent);
+        detach_mnt(root.mnt, &root_parent);
         /* mount old root on put_old */
-        attach_mnt(user_nd.path.mnt, &old_nd.path);
+        attach_mnt(root.mnt, &old_nd.path);
         /* mount new_root on / */
         attach_mnt(new_nd.path.mnt, &root_parent);
         touch_mnt_namespace(current->nsproxy->mnt_ns);
         spin_unlock(&vfsmount_lock);
-        chroot_fs_refs(&user_nd.path, &new_nd.path);
-        security_sb_post_pivotroot(&user_nd.path, &new_nd.path);
+        chroot_fs_refs(&root, &new_nd.path);
+        security_sb_post_pivotroot(&root, &new_nd.path);
         error = 0;
         path_put(&root_parent);
         path_put(&parent_path);
 out2:
         mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex);
         up_write(&namespace_sem);
-        path_put(&user_nd.path);
+        path_put(&root);
         path_put(&old_nd.path);
 out1:
         path_put(&new_nd.path);
 out0:
-        unlock_kernel();
         return error;
 out3:
         spin_unlock(&vfsmount_lock);