smb3: add way to control slow response threshold for logging and stats

[Steve French]

(Thanks to Metze for suggestion)

/proc/fs/cifs/Stats when CONFIG_CIFS_STATS2 is enabled logs 'slow'
responses, but depending on the server you are debugging a
one second timeout may be too fast, so allow setting it to
a larger number of seconds via new module parameter

/sys/module/cifs/parameters/slow_rsp_threshold

or via modprobe:

slow_rsp_threshold:Amount of time (in seconds) to wait before
logging that a response is delayed.
Default: 1 (if set to 0 disables msg). (uint)

Signed-off-by: Steve French <stfrench at microsoft.com>
---
 fs/cifs/cifsfs.c    | 13 +++++++++++++
 fs/cifs/cifsglob.h  |  1 +
 fs/cifs/transport.c |  7 ++++---
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 7065426b3280..45ea2429ab15 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -81,6 +81,14 @@ module_param(cifs_max_pending, uint, 0444);
 MODULE_PARM_DESC(cifs_max_pending, "Simultaneous requests to server for "
                    "CIFS/SMB1 dialect (N/A for SMB3) "
                    "Default: 32767 Range: 2 to 32767.");
+#ifdef CONFIG_CIFS_STATS2
+unsigned int slow_rsp_threshold = 1;
+module_param(slow_rsp_threshold, uint, 0644);
+MODULE_PARM_DESC(slow_rsp_threshold, "Amount of time (in seconds) to wait "
+                   "before logging that a response is delayed. "
+                   "Default: 1 (if set to 0 disables msg).");
+#endif /* STATS2 */
+
 module_param(enable_oplocks, bool, 0644);
 MODULE_PARM_DESC(enable_oplocks, "Enable or disable oplocks. Default: y/Y/1");

@@ -1418,6 +1426,11 @@ init_cifs(void)
 #ifdef CONFIG_CIFS_STATS2
     atomic_set(&totBufAllocCount, 0);
     atomic_set(&totSmBufAllocCount, 0);
+    if (slow_rsp_threshold < 1)
+        cifs_dbg(FYI, "slow_response_threshold msgs disabled\n");
+    else if (slow_rsp_threshold > 32767)
+        cifs_dbg(VFS,
+               "slow response threshold set higher than recommended\n");
 #endif /* CONFIG_CIFS_STATS2 */

     atomic_set(&midCount, 0);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 9dcaed031843..d59588e4aeb4 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1715,6 +1715,7 @@ GLOBAL_EXTERN atomic_t bufAllocCount;    /*
current number allocated  */
 #ifdef CONFIG_CIFS_STATS2
 GLOBAL_EXTERN atomic_t totBufAllocCount; /* total allocated over all time */
 GLOBAL_EXTERN atomic_t totSmBufAllocCount;
+extern unsigned int slow_rsp_threshold; /* number of secs before logging */
 #endif
 GLOBAL_EXTERN atomic_t smBufAllocCount;
 GLOBAL_EXTERN atomic_t midCount;
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index b48f43963da6..fe49733766d6 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -113,9 +113,10 @@ DeleteMidQEntry(struct mid_q_entry *midEntry)
         cifs_small_buf_release(midEntry->resp_buf);
 #ifdef CONFIG_CIFS_STATS2
     now = jiffies;
-    /* commands taking longer than one second are indications that
-       something is wrong, unless it is quite a slow link or server */
-    if (time_after(now, midEntry->when_alloc + HZ) &&
+    /* commands taking longer than one second (default) can be indications
+       that something is wrong, unless it is quite a slow link or server */
+    if ((slow_rsp_threshold != 0) &&
+        time_after(now, midEntry->when_alloc + slow_rsp_threshold) &&
         (midEntry->command != command)) {
         /* smb2slowcmd[NUMBER_OF_SMB2_COMMANDS] counts by command */
         if ((le16_to_cpu(midEntry->command) < NUMBER_OF_SMB2_COMMANDS) &&
-- 

-- 
Thanks,

Steve
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