From: Steve French <stfrench@microsoft.com>
Date: Tue, 18 Sep 2018 14:05:18 -0500
Subject: [PATCH] smb3: add way to control slow response threshold for logging
and stats
Git-commit: 00778e2294d560361e2ed4e94cc003351a2d82d9
Patch-mainline: v4.20-rc1
References: bsc#1144333
/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>
Acked-by: Aurelien Aptel <aaptel@suse.com>
---
fs/cifs/cifsfs.c | 13 +++++++++++++
fs/cifs/cifsglob.h | 1 +
fs/cifs/transport.c | 15 ++++++++++++---
3 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index af6c2e1795ef..ba0054604f85 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 (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 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 333729cf46cd..a1a1199578d5 100644
--- 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) &&
--
2.16.4