fault-inject: add ratelimit option

Current debug levels are not optimal.  Especially if one want to provoke
big numbers of faults(broken device simulator) then any verbose level will
produce giant numbers of identical logging messages.  Let's add ratelimit
parameter for that purpose.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/fault-inject.h

@@ -5,6 +5,7 @@
 
 #include <linux/types.h>
 #include <linux/debugfs.h>
+#include <linux/ratelimit.h>
 #include <linux/atomic.h>
 
 /*
@@ -25,14 +26,18 @@ struct fault_attr {
 	unsigned long reject_end;
 
 	unsigned long count;
+	struct ratelimit_state ratelimit_state;
+	struct dentry *dname;
 };
 
-#define FAULT_ATTR_INITIALIZER {				\
-		.interval = 1,					\
-		.times = ATOMIC_INIT(1),			\
-		.require_end = ULONG_MAX,			\
-		.stacktrace_depth = 32,				\
-		.verbose = 2,					\
+#define FAULT_ATTR_INITIALIZER {					\
+		.interval = 1,						\
+		.times = ATOMIC_INIT(1),				\
+		.require_end = ULONG_MAX,				\
+		.stacktrace_depth = 32,					\
+		.ratelimit_state = RATELIMIT_STATE_INIT_DISABLED,	\
+		.verbose = 2,						\
+		.dname = NULL,						\
 	}
 
 #define DECLARE_FAULT_ATTR(name) struct fault_attr name = FAULT_ATTR_INITIALIZER

lib/fault-inject.c

@@ -40,10 +40,16 @@ EXPORT_SYMBOL_GPL(setup_fault_attr);
 
 static void fail_dump(struct fault_attr *attr)
 {
-	if (attr->verbose > 0)
-		printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure\n");
-	if (attr->verbose > 1)
-		dump_stack();
+	if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
+		printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
+		       "name %pd, interval %lu, probability %lu, "
+		       "space %d, times %d\n", attr->dname,
+		       attr->probability, attr->interval,
+		       atomic_read(&attr->space),
+		       atomic_read(&attr->times));
+		if (attr->verbose > 1)
+			dump_stack();
+	}
 }
 
 #define atomic_dec_not_zero(v)		atomic_add_unless((v), -1, 0)
@@ -202,6 +208,12 @@ struct dentry *fault_create_debugfs_attr(const char *name,
 		goto fail;
 	if (!debugfs_create_ul("verbose", mode, dir, &attr->verbose))
 		goto fail;
+	if (!debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
+				&attr->ratelimit_state.interval))
+		goto fail;
+	if (!debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
+				&attr->ratelimit_state.burst))
+		goto fail;
 	if (!debugfs_create_bool("task-filter", mode, dir, &attr->task_filter))
 		goto fail;
 
@@ -222,6 +234,7 @@ struct dentry *fault_create_debugfs_attr(const char *name,
 
 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 
+	attr->dname = dget(dir);
 	return dir;
 fail:
 	debugfs_remove_recursive(dir);