[PATCH] reduce stack footprint in namespace.c

A lot of places misuse struct nameidata when they need struct path.

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

1 files changed, 37 insertions, 35 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 7953c96a2071..6324dfc80dc6 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -155,15 +155,15 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns)
         }
 }
 
-static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)
+static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
 {
-        old_nd->path.dentry = mnt->mnt_mountpoint;
-        old_nd->path.mnt = mnt->mnt_parent;
+        old_path->dentry = mnt->mnt_mountpoint;
+        old_path->mnt = mnt->mnt_parent;
         mnt->mnt_parent = mnt;
         mnt->mnt_mountpoint = mnt->mnt_root;
         list_del_init(&mnt->mnt_child);
         list_del_init(&mnt->mnt_hash);
-        old_nd->path.dentry->d_mounted--;
+        old_path->dentry->d_mounted--;
 }
 
 void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
@@ -174,12 +174,12 @@ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
         dentry->d_mounted++;
 }
 
-static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)
+static void attach_mnt(struct vfsmount *mnt, struct path *path)
 {
-        mnt_set_mountpoint(nd->path.mnt, nd->path.dentry, mnt);
+        mnt_set_mountpoint(path->mnt, path->dentry, mnt);
         list_add_tail(&mnt->mnt_hash, mount_hashtable +
-                        hash(nd->path.mnt, nd->path.dentry));
-        list_add_tail(&mnt->mnt_child, &nd->path.mnt->mnt_mounts);
+                        hash(path->mnt, path->dentry));
+        list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
 }
 
 /*
@@ -744,7 +744,7 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
                                         int flag)
 {
         struct vfsmount *res, *p, *q, *r, *s;
-        struct nameidata nd;
+        struct path path;
 
         if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
                 return NULL;
@@ -769,14 +769,14 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
                                 q = q->mnt_parent;
                         }
                         p = s;
-                        nd.path.mnt = q;
-                        nd.path.dentry = p->mnt_mountpoint;
+                        path.mnt = q;
+                        path.dentry = p->mnt_mountpoint;
                         q = clone_mnt(p, p->mnt_root, flag);
                         if (!q)
                                 goto Enomem;
                         spin_lock(&vfsmount_lock);
                         list_add_tail(&q->mnt_list, &res->mnt_list);
-                        attach_mnt(q, &nd);
+                        attach_mnt(q, &path);
                         spin_unlock(&vfsmount_lock);
                 }
         }
@@ -876,11 +876,11 @@ void drop_collected_mounts(struct vfsmount *mnt)
  * in allocations.
  */
 static int attach_recursive_mnt(struct vfsmount *source_mnt,
-                        struct nameidata *nd, struct nameidata *parent_nd)
+                        struct path *path, struct path *parent_path)
 {
         LIST_HEAD(tree_list);
-        struct vfsmount *dest_mnt = nd->path.mnt;
-        struct dentry *dest_dentry = nd->path.dentry;
+        struct vfsmount *dest_mnt = path->mnt;
+        struct dentry *dest_dentry = path->dentry;
         struct vfsmount *child, *p;
 
         if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
@@ -892,9 +892,9 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
         }
 
         spin_lock(&vfsmount_lock);
-        if (parent_nd) {
-                detach_mnt(source_mnt, parent_nd);
-                attach_mnt(source_mnt, nd);
+        if (parent_path) {
+                detach_mnt(source_mnt, parent_path);
+                attach_mnt(source_mnt, path);
                 touch_mnt_namespace(current->nsproxy->mnt_ns);
         } else {
                 mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
@@ -930,7 +930,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
 
         err = -ENOENT;
         if (IS_ROOT(nd->path.dentry) || !d_unhashed(nd->path.dentry))
-                err = attach_recursive_mnt(mnt, nd, NULL);
+                err = attach_recursive_mnt(mnt, &nd->path, NULL);
 out_unlock:
         mutex_unlock(&nd->path.dentry->d_inode->i_mutex);
         if (!err)
@@ -1059,7 +1059,8 @@ static inline int tree_contains_unbindable(struct vfsmount *mnt)
  */
 static noinline int do_move_mount(struct nameidata *nd, char *old_name)
 {
-        struct nameidata old_nd, parent_nd;
+        struct nameidata old_nd;
+        struct path parent_path;
         struct vfsmount *p;
         int err = 0;
         if (!capable(CAP_SYS_ADMIN))
@@ -1114,7 +1115,7 @@ static noinline int do_move_mount(struct nameidata *nd, char *old_name)
                 if (p == old_nd.path.mnt)
                         goto out1;
 
-        err = attach_recursive_mnt(old_nd.path.mnt, nd, &parent_nd);
+        err = attach_recursive_mnt(old_nd.path.mnt, &nd->path, &parent_path);
         if (err)
                 goto out1;
 
@@ -1128,7 +1129,7 @@ out1:
 out:
         up_write(&namespace_sem);
         if (!err)
-                path_put(&parent_nd.path);
+                path_put(&parent_path);
         path_put(&old_nd.path);
         return err;
 }
@@ -1683,7 +1684,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
                 path_put(&old_pwd);
 }
 
-static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
+static void chroot_fs_refs(struct path *old_root, struct path *new_root)
 {
         struct task_struct *g, *p;
         struct fs_struct *fs;
@@ -1695,12 +1696,12 @@ static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
                 if (fs) {
                         atomic_inc(&fs->count);
                         task_unlock(p);
-                        if (fs->root.dentry == old_nd->path.dentry
-                            && fs->root.mnt == old_nd->path.mnt)
-                                set_fs_root(fs, &new_nd->path);
-                        if (fs->pwd.dentry == old_nd->path.dentry
-                            && fs->pwd.mnt == old_nd->path.mnt)
-                                set_fs_pwd(fs, &new_nd->path);
+                        if (fs->root.dentry == old_root->dentry
+                            && fs->root.mnt == old_root->mnt)
+                                set_fs_root(fs, new_root);
+                        if (fs->pwd.dentry == old_root->dentry
+                            && fs->pwd.mnt == old_root->mnt)
+                                set_fs_pwd(fs, new_root);
                         put_fs_struct(fs);
                 } else
                         task_unlock(p);
@@ -1737,7 +1738,8 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
                                const char __user * put_old)
 {
         struct vfsmount *tmp;
-        struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd;
+        struct nameidata new_nd, old_nd, user_nd;
+        struct path parent_path, root_parent;
         int error;
 
         if (!capable(CAP_SYS_ADMIN))
@@ -1811,19 +1813,19 @@ asmlinkage long sys_pivot_root(const char __user * new_root,
                         goto out3;
         } else if (!is_subdir(old_nd.path.dentry, new_nd.path.dentry))
                 goto out3;
-        detach_mnt(new_nd.path.mnt, &parent_nd);
+        detach_mnt(new_nd.path.mnt, &parent_path);
         detach_mnt(user_nd.path.mnt, &root_parent);
         /* mount old root on put_old */
-        attach_mnt(user_nd.path.mnt, &old_nd);
+        attach_mnt(user_nd.path.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, &new_nd);
+        chroot_fs_refs(&user_nd.path, &new_nd.path);
         security_sb_post_pivotroot(&user_nd, &new_nd);
         error = 0;
-        path_put(&root_parent.path);
-        path_put(&parent_nd.path);
+        path_put(&root_parent);
+        path_put(&parent_path);
 out2:
         mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex);
         up_write(&namespace_sem);