9p: Fix memory leak in v9fs_mount

v9fs_mount
  v9fs_session_init
    v9fs_cache_session_get_cookie
      v9fs_random_cachetag                     -->alloc cachetag
      v9ses->fscache = fscache_acquire_cookie  -->maybe NULL
  sb = sget                                    -->fail, goto clunk
clunk_fid:
  v9fs_session_close
    if (v9ses->fscache)                        -->NULL
      kfree(v9ses->cachetag)

Thus memleak happens.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 60e78d2 ("9p: Add fscache support to 9p")
Cc: <[email protected]> # v2.6.32+
Signed-off-by: Zheng Bin <[email protected]>
Signed-off-by: Dominique Martinet <[email protected]>

fs/9p/v9fs.c

@@ -500,10 +500,9 @@ void v9fs_session_close(struct v9fs_session_info *v9ses)
 	}
 
 #ifdef CONFIG_9P_FSCACHE
-	if (v9ses->fscache) {
+	if (v9ses->fscache)
 		v9fs_cache_session_put_cookie(v9ses);
-		kfree(v9ses->cachetag);
-	}
+	kfree(v9ses->cachetag);
 #endif
 	kfree(v9ses->uname);
 	kfree(v9ses->aname);