9p: Uninitialized variable in v9fs_writeback_fid()

If v9fs_fid_lookup_with_uid() fails then "fid" is not initialized.

The v9fs_fid_lookup_with_uid() can't return NULL.  If it returns an
error pointer then we can still pass that to clone_fid() and it will
return the error pointer back again.

Fixes: 6636b6dc ("9p: add refcount to p9_fid struct")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

fs/9p/fid.c

@@ -302,8 +302,7 @@ struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
 	struct p9_fid *fid, *ofid;
 
 	ofid = v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0);
-	if (ofid && !IS_ERR(ofid))
-		fid = clone_fid(ofid);
+	fid = clone_fid(ofid);
 	if (IS_ERR(fid))
 		goto error_out;
 	p9_client_clunk(ofid);