Btrfs: check file pointer in btrfs_sync_file

fsync can be called by NFS with a null file pointer, and btrfs was
oopsing in this case.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3e8023e..872f104 100644 (file)
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1222,7 +1222,7 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
        /*
         * ok we haven't committed the transaction yet, lets do a commit
         */
-       if (file->private_data)
+       if (file && file->private_data)
                btrfs_ioctl_trans_end(file);
 
        trans = btrfs_start_transaction(root, 1);
@@ -1231,7 +1231,7 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
                goto out;
        }
 
-       ret = btrfs_log_dentry_safe(trans, root, file->f_dentry);
+       ret = btrfs_log_dentry_safe(trans, root, dentry);
        if (ret < 0)
                goto out;
 
@@ -1245,7 +1245,7 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
         * file again, but that will end up using the synchronization
         * inside btrfs_sync_log to keep things safe.
         */
-       mutex_unlock(&file->f_dentry->d_inode->i_mutex);
+       mutex_unlock(&dentry->d_inode->i_mutex);
 
        if (ret > 0) {
                ret = btrfs_commit_transaction(trans, root);
@@ -1253,7 +1253,7 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
                btrfs_sync_log(trans, root);
                ret = btrfs_end_transaction(trans, root);
        }
-       mutex_lock(&file->f_dentry->d_inode->i_mutex);
+       mutex_lock(&dentry->d_inode->i_mutex);
 out:
        return ret > 0 ? EIO : ret;
 }