Push BKL into do_mount()
[linux-2.6.git] / fs / namespace.c
index 22ae06a..4740f7b 100644 (file)
@@ -265,6 +265,46 @@ out:
 EXPORT_SYMBOL_GPL(mnt_want_write);
 
 /**
+ * mnt_clone_write - get write access to a mount
+ * @mnt: the mount on which to take a write
+ *
+ * This is effectively like mnt_want_write, except
+ * it must only be used to take an extra write reference
+ * on a mountpoint that we already know has a write reference
+ * on it. This allows some optimisation.
+ *
+ * After finished, mnt_drop_write must be called as usual to
+ * drop the reference.
+ */
+int mnt_clone_write(struct vfsmount *mnt)
+{
+       /* superblock may be r/o */
+       if (__mnt_is_readonly(mnt))
+               return -EROFS;
+       preempt_disable();
+       inc_mnt_writers(mnt);
+       preempt_enable();
+       return 0;
+}
+EXPORT_SYMBOL_GPL(mnt_clone_write);
+
+/**
+ * mnt_want_write_file - get write access to a file's mount
+ * @file: the file who's mount on which to take a write
+ *
+ * This is like mnt_want_write, but it takes a file and can
+ * do some optimisations if the file is open for write already
+ */
+int mnt_want_write_file(struct file *file)
+{
+       if (!(file->f_mode & FMODE_WRITE))
+               return mnt_want_write(file->f_path.mnt);
+       else
+               return mnt_clone_write(file->f_path.mnt);
+}
+EXPORT_SYMBOL_GPL(mnt_want_write_file);
+
+/**
  * mnt_drop_write - give up write access to a mount
  * @mnt: the mount on which to give up write access
  *
@@ -1344,7 +1384,7 @@ static int graft_tree(struct vfsmount *mnt, struct path *path)
                goto out_unlock;
 
        err = -ENOENT;
-       if (IS_ROOT(path->dentry) || !d_unhashed(path->dentry))
+       if (!d_unlinked(path->dentry))
                err = attach_recursive_mnt(mnt, path, NULL);
 out_unlock:
        mutex_unlock(&path->dentry->d_inode->i_mutex);
@@ -1526,7 +1566,7 @@ static int do_move_mount(struct path *path, char *old_name)
        if (IS_DEADDIR(path->dentry->d_inode))
                goto out1;
 
-       if (!IS_ROOT(path->dentry) && d_unhashed(path->dentry))
+       if (d_unlinked(path->dentry))
                goto out1;
 
        err = -EINVAL;
@@ -1881,6 +1921,7 @@ long do_mount(char *dev_name, char *dir_name, char *type_page,
        if (retval)
                goto dput_out;
 
+       lock_kernel();
        if (flags & MS_REMOUNT)
                retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags,
                                    data_page);
@@ -1893,6 +1934,7 @@ long do_mount(char *dev_name, char *dir_name, char *type_page,
        else
                retval = do_new_mount(&path, type_page, flags, mnt_flags,
                                      dev_name, data_page);
+       unlock_kernel();
 dput_out:
        path_put(&path);
        return retval;
@@ -2006,10 +2048,8 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
        if (retval < 0)
                goto out3;
 
-       lock_kernel();
        retval = do_mount((char *)dev_page, dir_page, (char *)type_page,
                          flags, (void *)data_page);
-       unlock_kernel();
        free_page(data_page);
 
 out3:
@@ -2089,9 +2129,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        error = -ENOENT;
        if (IS_DEADDIR(new.dentry->d_inode))
                goto out2;
-       if (d_unhashed(new.dentry) && !IS_ROOT(new.dentry))
+       if (d_unlinked(new.dentry))
                goto out2;
-       if (d_unhashed(old.dentry) && !IS_ROOT(old.dentry))
+       if (d_unlinked(old.dentry))
                goto out2;
        error = -EBUSY;
        if (new.mnt == root.mnt ||