smb3: display stats counters for number of slow commands

When CONFIG_CIFS_STATS2 is enabled keep counters for slow
commands (ie server took longer than 1 second to respond)
by SMB2/SMB3 command code.  This can help in diagnosing
whether performance problems are on server (instead of
client) and which commands are causing the problem.

Sample output (the new lines contain words "slow responses ...")

$ cat /proc/fs/cifs/Stats
Resources in use
CIFS Session: 1
Share (unique mount targets): 2
SMB Request/Response Buffer: 1 Pool size: 5
SMB Small Req/Resp Buffer: 1 Pool size: 30
Total Large 10 Small 490 Allocations
Operations (MIDs): 0

0 session 0 share reconnects
Total vfs operations: 67 maximum at one time: 2
4 slow responses from localhost for command 5
1 slow responses from localhost for command 6
1 slow responses from localhost for command 14
1 slow responses from localhost for command 16

1) \\localhost\test
SMBs: 243
Bytes read: 1024000  Bytes written: 104857600
TreeConnects: 1 total 0 failed
TreeDisconnects: 0 total 0 failed
Creates: 40 total 0 failed
Closes: 39 total 0 failed
...
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>

fs/cifs/cifs_debug.c

@@ -378,6 +378,8 @@ static ssize_t cifs_stats_proc_write(struct file *file,
 	rc = kstrtobool_from_user(buffer, count, &bv);
 	if (rc == 0) {
 #ifdef CONFIG_CIFS_STATS2
+		int i;
+
 		atomic_set(&totBufAllocCount, 0);
 		atomic_set(&totSmBufAllocCount, 0);
 #endif /* CONFIG_CIFS_STATS2 */
@@ -389,6 +391,10 @@ static ssize_t cifs_stats_proc_write(struct file *file,
 		list_for_each(tmp1, &cifs_tcp_ses_list) {
 			server = list_entry(tmp1, struct TCP_Server_Info,
 					    tcp_ses_list);
+#ifdef CONFIG_CIFS_STATS2
+			for (i = 0; i < NUMBER_OF_SMB2_COMMANDS; i++)
+				atomic_set(&server->smb2slowcmd[i], 0);
+#endif /* CONFIG_CIFS_STATS2 */
 			list_for_each(tmp2, &server->smb_ses_list) {
 				ses = list_entry(tmp2, struct cifs_ses,
 						 smb_ses_list);
@@ -417,13 +423,15 @@ static ssize_t cifs_stats_proc_write(struct file *file,
 static int cifs_stats_proc_show(struct seq_file *m, void *v)
 {
 	int i;
+#ifdef CONFIG_CIFS_STATS2
+	int j;
+#endif /* STATS2 */
 	struct list_head *tmp1, *tmp2, *tmp3;
 	struct TCP_Server_Info *server;
 	struct cifs_ses *ses;
 	struct cifs_tcon *tcon;
 
-	seq_printf(m,
-			"Resources in use\nCIFS Session: %d\n",
+	seq_printf(m, "Resources in use\nCIFS Session: %d\n",
 			sesInfoAllocCount.counter);
 	seq_printf(m, "Share (unique mount targets): %d\n",
 			tconInfoAllocCount.counter);
@@ -452,6 +460,13 @@ static int cifs_stats_proc_show(struct seq_file *m, void *v)
 	list_for_each(tmp1, &cifs_tcp_ses_list) {
 		server = list_entry(tmp1, struct TCP_Server_Info,
 				    tcp_ses_list);
+#ifdef CONFIG_CIFS_STATS2
+		for (j = 0; j < NUMBER_OF_SMB2_COMMANDS; j++)
+			if (atomic_read(&server->smb2slowcmd[j]))
+				seq_printf(m, "%d slow responses from %s for command %d\n",
+					atomic_read(&server->smb2slowcmd[j]),
+					server->hostname, j);
+#endif /* STATS2 */
 		list_for_each(tmp2, &server->smb_ses_list) {
 			ses = list_entry(tmp2, struct cifs_ses,
 					 smb_ses_list);

fs/cifs/cifsglob.h

@@ -680,7 +680,8 @@ struct TCP_Server_Info {
 #ifdef CONFIG_CIFS_STATS2
 	atomic_t in_send; /* requests trying to send */
 	atomic_t num_waiters;   /* blocked waiting to get in sendrecv */
-#endif
+	atomic_t smb2slowcmd[NUMBER_OF_SMB2_COMMANDS]; /* count resps > 1 sec */
+#endif /* STATS2 */
 	unsigned int	max_read;
 	unsigned int	max_write;
 	__le16	cipher_type;

fs/cifs/transport.c

@@ -117,6 +117,11 @@ DeleteMidQEntry(struct mid_q_entry *midEntry)
 	   something is wrong, unless it is quite a slow link or server */
 	if (time_after(now, midEntry->when_alloc + HZ) &&
 	    (midEntry->command != command)) {
+		/* smb2slowcmd[NUMBER_OF_SMB2_COMMANDS] counts by command */
+		if ((le16_to_cpu(midEntry->command) < NUMBER_OF_SMB2_COMMANDS) &&
+		    (le16_to_cpu(midEntry->command) >= 0))
+			cifs_stats_inc(&midEntry->server->smb2slowcmd[le16_to_cpu(midEntry->command)]);
+
 		trace_smb3_slow_rsp(le16_to_cpu(midEntry->command),
 			       midEntry->mid, midEntry->pid,
 			       midEntry->when_sent, midEntry->when_received);