smb3: display max smb3 requests in flight at any one time

Displayed in /proc/fs/cifs/Stats once for each
socket we are connected to.

This allows us to find out what the maximum number of
requests that had been in flight (at any one time). Note that
/proc/fs/cifs/Stats can be reset if you want to look for
maximum over a small period of time.

Sample output (immediately after mount):

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
Operations (MIDs): 0

0 session 0 share reconnects
Total vfs operations: 5 maximum at one time: 2

Max requests in flight: 2
1) \\localhost\scratch
SMBs: 18
Bytes read: 0  Bytes written: 0
...

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

5 files changed, 10 insertions, 0 deletions

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index a38d796f5ffe..0b4eee3bed66 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -452,6 +452,7 @@ 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);
+                        server->max_in_flight = 0;
 #ifdef CONFIG_CIFS_STATS2
                         for (i = 0; i < NUMBER_OF_SMB2_COMMANDS; i++) {
                                 atomic_set(&server->num_cmds[i], 0);
@@ -526,6 +527,7 @@ 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);
+                seq_printf(m, "\nMax requests in flight: %d", server->max_in_flight);
 #ifdef CONFIG_CIFS_STATS2
                 seq_puts(m, "\nTotal time spent processing by command. Time ");
                 seq_printf(m, "units are jiffies (%d per second)\n", HZ);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 6987fbc5a24a..ef2199913217 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -677,6 +677,7 @@ struct TCP_Server_Info {
         unsigned int credits;  /* send no more requests at once */
         unsigned int max_credits; /* can override large 32000 default at mnt */
         unsigned int in_flight;  /* number of requests on the wire to server */
+        unsigned int max_in_flight; /* max number of requests that were on wire */
         spinlock_t req_lock;  /* protect the two values above */
         struct mutex srv_mutex;
         struct task_struct *tsk;
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index e70112d67b0e..df1ccb581828 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -2728,6 +2728,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
         tcp_ses->tcp_nodelay = volume_info->sockopt_tcp_nodelay;
         tcp_ses->rdma = volume_info->rdma;
         tcp_ses->in_flight = 0;
+        tcp_ses->max_in_flight = 0;
         tcp_ses->credits = 1;
         init_waitqueue_head(&tcp_ses->response_q);
         init_waitqueue_head(&tcp_ses->request_q);
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 72b3e39d7f4f..9b74149b471f 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -203,6 +203,8 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
                         credits->instance = server->reconnect_instance;
                         server->credits -= credits->value;
                         server->in_flight++;
+                        if (server->in_flight > server->max_in_flight)
+                                server->max_in_flight = server->in_flight;
                         break;
                 }
         }
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 4fccb90492e9..308ad0f495e1 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -532,6 +532,8 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
         if ((flags & CIFS_TIMEOUT_MASK) == CIFS_NON_BLOCKING) {
                 /* oplock breaks must not be held up */
                 server->in_flight++;
+                if (server->in_flight > server->max_in_flight)
+                        server->max_in_flight = server->in_flight;
                 *credits -= 1;
                 *instance = server->reconnect_instance;
                 spin_unlock(&server->req_lock);
@@ -608,6 +610,8 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
                         if ((flags & CIFS_TIMEOUT_MASK) != CIFS_BLOCKING_OP) {
                                 *credits -= num_credits;
                                 server->in_flight += num_credits;
+                                if (server->in_flight > server->max_in_flight)
+                                        server->max_in_flight = server->in_flight;
                                 *instance = server->reconnect_instance;
                         }
                         spin_unlock(&server->req_lock);