From 60396eccc04bbecfc85404ce10903610e082517d Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Mon, 19 Oct 2020 18:18:15 -0500
Subject: [PATCH] smb3: add dynamic trace point to trace when credits obtained
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SMB3 crediting is used for flow control, and it can be useful to
trace for problem determination how many credits were acquired
and for which operation.

Here is an example ("trace-cmd record -e *add_credits"):
cifsd-9522    [010] ....  5995.202712: smb3_add_credits:
	server=localhost current_mid=0x12 credits=373 credits_to_add=10
cifsd-9522    [010] ....  5995.204040: smb3_add_credits:
	server=localhost current_mid=0x15 credits=400 credits_to_add=30

Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/smb2ops.c   |  4 +++-
 fs/cifs/trace.h     | 18 ++++++++++++------
 fs/cifs/transport.c |  5 +++--
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 0dfa832a3de0..f085fe32c342 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -72,7 +72,7 @@ smb2_add_credits(struct TCP_Server_Info *server,
 	/* eg found case where write overlapping reconnect messed up credits */
 	if (((optype & CIFS_OP_MASK) == CIFS_NEG_OP) && (*val != 0))
 		trace_smb3_reconnect_with_invalid_credits(server->CurrentMid,
-			server->hostname, *val);
+			server->hostname, *val, add);
 	if ((instance == 0) || (instance == server->reconnect_instance))
 		*val += add;
 	else
@@ -121,6 +121,8 @@ smb2_add_credits(struct TCP_Server_Info *server,
 		cifs_dbg(FYI, "disabling oplocks\n");
 		break;
 	default:
+		trace_smb3_add_credits(server->CurrentMid,
+			server->hostname, rc, add);
 		cifs_dbg(FYI, "add %u credits total=%d\n", add, rc);
 	}
 }
diff --git a/fs/cifs/trace.h b/fs/cifs/trace.h
index eef4b08c7208..90e0fab69bb8 100644
--- a/fs/cifs/trace.h
+++ b/fs/cifs/trace.h
@@ -878,33 +878,39 @@ DEFINE_SMB3_RECONNECT_EVENT(partial_send_reconnect);
 DECLARE_EVENT_CLASS(smb3_credit_class,
 	TP_PROTO(__u64	currmid,
 		char *hostname,
-		int credits),
-	TP_ARGS(currmid, hostname, credits),
+		int credits,
+		int credits_to_add),
+	TP_ARGS(currmid, hostname, credits, credits_to_add),
 	TP_STRUCT__entry(
 		__field(__u64, currmid)
 		__field(char *, hostname)
 		__field(int, credits)
+		__field(int, credits_to_add)
 	),
 	TP_fast_assign(
 		__entry->currmid = currmid;
 		__entry->hostname = hostname;
 		__entry->credits = credits;
+		__entry->credits_to_add = credits_to_add;
 	),
-	TP_printk("server=%s current_mid=0x%llx credits=%d",
+	TP_printk("server=%s current_mid=0x%llx credits=%d credits_to_add=%d",
 		__entry->hostname,
 		__entry->currmid,
-		__entry->credits)
+		__entry->credits,
+		__entry->credits_to_add)
 )
 
 #define DEFINE_SMB3_CREDIT_EVENT(name)        \
 DEFINE_EVENT(smb3_credit_class, smb3_##name,  \
 	TP_PROTO(__u64	currmid,		\
 		char *hostname,			\
-		int  credits),			\
-	TP_ARGS(currmid, hostname, credits))
+		int  credits,			\
+		int  credits_to_add),		\
+	TP_ARGS(currmid, hostname, credits, credits_to_add))
 
 DEFINE_SMB3_CREDIT_EVENT(reconnect_with_invalid_credits);
 DEFINE_SMB3_CREDIT_EVENT(credit_timeout);
+DEFINE_SMB3_CREDIT_EVENT(add_credits);
 
 #endif /* _CIFS_TRACE_H */
 
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index ac7632482736..e27e255d40dd 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -563,7 +563,7 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 			cifs_num_waiters_dec(server);
 			if (!rc) {
 				trace_smb3_credit_timeout(server->CurrentMid,
-					server->hostname, num_credits);
+					server->hostname, num_credits, 0);
 				cifs_server_dbg(VFS, "wait timed out after %d ms\n",
 					 timeout);
 				return -ENOTSUPP;
@@ -604,7 +604,8 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 				if (!rc) {
 					trace_smb3_credit_timeout(
 						server->CurrentMid,
-						server->hostname, num_credits);
+						server->hostname, num_credits,
+						0);
 					cifs_server_dbg(VFS, "wait timed out after %d ms\n",
 						 timeout);
 					return -ENOTSUPP;
-- 
2.25.1

