Btrfs: use mnt_want_write_file instead of mnt_want_write

mnt_want_write_file is faster when file has been opened for write.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b8034dc62e38fcced8bedaccb8b8a6bd7157c921..13ed1c9534cc672a9682a776c0a161bace2aa5e3 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3265,7 +3265,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       ret = mnt_want_write(file->f_path.mnt);
+       ret = mnt_want_write_file(file);
        if (ret)
                return ret;
 
@@ -3335,7 +3335,7 @@ out_bargs:
 out:
        mutex_unlock(&fs_info->balance_mutex);
        mutex_unlock(&fs_info->volume_mutex);
-       mnt_drop_write(file->f_path.mnt);
+       mnt_drop_write_file(file);
        return ret;
 }