[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>

diff --git a/fs/namespace.c b/fs/namespace.c
index 87d2d82010bb089de948a4b5c571d3883f8b5fe7..1bf302d0478b9b52d5a302278febdf40d474eda5 100644 (file)
--- 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);