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

/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)

Recommended values are 0 (disabled) to 32767 (9 hours) with
the default remaining as 1 second.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index af6c2e1..ba00546 100644 (file)
--- 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 (0 to 32767)\n");
 #endif /* CONFIG_CIFS_STATS2 */
 
        atomic_set(&midCount, 0);

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 9dcaed0..d59588e 100644 (file)
--- 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 333729c..a1a1199 100644 (file)
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -113,9 +113,18 @@ 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 a very
+        * busy server. Note that this calc is unlikely or impossible to wrap
+        * as long as slow_rsp_threshold is not set way above recommended max
+        * value (32767 ie 9 hours) and is generally harmless even if wrong
+        * since only affects debug counters - so leaving the calc as simple
+        * comparison rather than doing multiple conversions and overflow
+        * checks
+        */
+       if ((slow_rsp_threshold != 0) &&
+           time_after(now, midEntry->when_alloc + (slow_rsp_threshold * HZ)) &&
            (midEntry->command != command)) {
                /* smb2slowcmd[NUMBER_OF_SMB2_COMMANDS] counts by command */
                if ((le16_to_cpu(midEntry->command) < NUMBER_OF_SMB2_COMMANDS) &&