[PATCH] lockd: Fix comment about NLMv3 backwards compatibility

[Pali Rohár]

NLMv2 is completely different protocol than NLMv1 and NLMv3, and in
original Sun implementation is used for RPC loopback callbacks from statd
to lockd services. Linux does not use nor does not implement NLMv2.

Hence, NLMv3 is not backward compatible with NLMv2. But NLMv3 is backward
compatible with NLMv1. Fix comment.

Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
---
 fs/lockd/clntxdr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/lockd/clntxdr.c b/fs/lockd/clntxdr.c
index a3e97278b997..81ffa521f945 100644
--- a/fs/lockd/clntxdr.c
+++ b/fs/lockd/clntxdr.c
@@ -3,7 +3,9 @@
  * linux/fs/lockd/clntxdr.c
  *
  * XDR functions to encode/decode NLM version 3 RPC arguments and results.
- * NLM version 3 is backwards compatible with NLM versions 1 and 2.
+ * NLM version 3 is backwards compatible with NLM version 1.
+ * NLM version 2 is different protocol used only for RPC loopback callbacks
+ * from statd to lockd and is not implemented on Linux.
  *
  * NLM client-side only.
  *
-- 
2.20.1