[S390] dasd: add enhanced DASD statistics interface

This patch extends the DASD statistics to allow for a more detailed
analysis of DASD I/O operations. In particular we want the statistics
to provide answers to the following questions:
- How many requests used a PAV alias?
- How many requests used High Performance FICON?
- How do read request perform versus write requests?

The existing DASD statistics interface has several shortcomings
- The interface for global data is a formatted text table in procfs
  (/proc/dasd/statistics). The layout is meant for human readers and
  is not to easy to parse. If values get to large for the table
  layout, they get scaled down.
- The statistics which are collected per block device can be
  accessed via an ioctl interface, which can only be extended by
  defining a new ioctl.
- There is no statistics interface for individual PAV base and alias
  devices.

To overcome theses shortcomings we create a new DASD statistics
interface in debugfs. This interface will contain one entry for global
data, one per DASD block device, and one per DASD base and alias
device. Each file contains the statistic data in easy to parse
name/value and name/array pairs. The existing interfaces will remain
functional, but they will not be extended.

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 71 insertions, 35 deletions

diff --git a/drivers/s390/block/dasd_proc.c b/drivers/s390/block/dasd_proc.c
index c4a6a31bd9cd..6c3c5364d082 100644
--- a/drivers/s390/block/dasd_proc.c
+++ b/drivers/s390/block/dasd_proc.c
@@ -32,28 +32,6 @@ static struct proc_dir_entry *dasd_proc_root_entry = NULL;
 static struct proc_dir_entry *dasd_devices_entry = NULL;
 static struct proc_dir_entry *dasd_statistics_entry = NULL;
 
-#ifdef CONFIG_DASD_PROFILE
-static char *
-dasd_get_user_string(const char __user *user_buf, size_t user_len)
-{
-	char *buffer;
-
-	buffer = kmalloc(user_len + 1, GFP_KERNEL);
-	if (buffer == NULL)
-		return ERR_PTR(-ENOMEM);
-	if (copy_from_user(buffer, user_buf, user_len) != 0) {
-		kfree(buffer);
-		return ERR_PTR(-EFAULT);
-	}
-	/* got the string, now strip linefeed. */
-	if (buffer[user_len - 1] == '\n')
-		buffer[user_len - 1] = 0;
-	else
-		buffer[user_len] = 0;
-	return buffer;
-}
-#endif /* CONFIG_DASD_PROFILE */
-
 static int
 dasd_devices_show(struct seq_file *m, void *v)
 {
@@ -167,6 +145,55 @@ static const struct file_operations dasd_devices_file_ops = {
 };
 
 #ifdef CONFIG_DASD_PROFILE
+static int dasd_stats_all_block_on(void)
+{
+	int i, rc;
+	struct dasd_device *device;
+
+	rc = 0;
+	for (i = 0; i < dasd_max_devindex; ++i) {
+		device = dasd_device_from_devindex(i);
+		if (IS_ERR(device))
+			continue;
+		if (device->block)
+			rc = dasd_profile_on(&device->block->profile);
+		dasd_put_device(device);
+		if (rc)
+			return rc;
+	}
+	return 0;
+}
+
+static void dasd_stats_all_block_off(void)
+{
+	int i;
+	struct dasd_device *device;
+
+	for (i = 0; i < dasd_max_devindex; ++i) {
+		device = dasd_device_from_devindex(i);
+		if (IS_ERR(device))
+			continue;
+		if (device->block)
+			dasd_profile_off(&device->block->profile);
+		dasd_put_device(device);
+	}
+}
+
+static void dasd_stats_all_block_reset(void)
+{
+	int i;
+	struct dasd_device *device;
+
+	for (i = 0; i < dasd_max_devindex; ++i) {
+		device = dasd_device_from_devindex(i);
+		if (IS_ERR(device))
+			continue;
+		if (device->block)
+			dasd_profile_reset(&device->block->profile);
+		dasd_put_device(device);
+	}
+}
+
 static void dasd_statistics_array(struct seq_file *m, unsigned int *array, int factor)
 {
 	int i;
@@ -183,18 +210,18 @@ static void dasd_statistics_array(struct seq_file *m, unsigned int *array, int f
 static int dasd_stats_proc_show(struct seq_file *m, void *v)
 {
 #ifdef CONFIG_DASD_PROFILE
-	struct dasd_profile_info_t *prof;
+	struct dasd_profile_info *prof;
 	int factor;
 
 	/* check for active profiling */
-	if (dasd_profile_level == DASD_PROFILE_OFF) {
+	if (!dasd_global_profile_level) {
 		seq_printf(m, "Statistics are off - they might be "
 				    "switched on using 'echo set on > "
 				    "/proc/dasd/statistics'\n");
 		return 0;
 	}
+	prof = &dasd_global_profile_data;
 
-	prof = &dasd_global_profile;
 	/* prevent counter 'overflow' on output */
 	for (factor = 1; (prof->dasd_io_reqs / factor) > 9999999;
 	     factor *= 10);
@@ -245,6 +272,7 @@ static ssize_t dasd_stats_proc_write(struct file *file,
 {
 #ifdef CONFIG_DASD_PROFILE
 	char *buffer, *str;
+	int rc;
 
 	if (user_len > 65536)
 		user_len = 65536;
@@ -259,32 +287,40 @@ static ssize_t dasd_stats_proc_write(struct file *file,
 		str = skip_spaces(str + 4);
 		if (strcmp(str, "on") == 0) {
 			/* switch on statistics profiling */
-			dasd_profile_level = DASD_PROFILE_ON;
+			rc = dasd_stats_all_block_on();
+			if (rc) {
+				dasd_stats_all_block_off();
+				goto out_error;
+			}
+			dasd_global_profile_reset();
+			dasd_global_profile_level = DASD_PROFILE_ON;
 			pr_info("The statistics feature has been switched "
 				"on\n");
 		} else if (strcmp(str, "off") == 0) {
 			/* switch off and reset statistics profiling */
-			memset(&dasd_global_profile,
-			       0, sizeof (struct dasd_profile_info_t));
-			dasd_profile_level = DASD_PROFILE_OFF;
+			dasd_global_profile_level = DASD_PROFILE_OFF;
+			dasd_global_profile_reset();
+			dasd_stats_all_block_off();
 			pr_info("The statistics feature has been switched "
 				"off\n");
 		} else
-			goto out_error;
+			goto out_parse_error;
 	} else if (strncmp(str, "reset", 5) == 0) {
 		/* reset the statistics */
-		memset(&dasd_global_profile, 0,
-		       sizeof (struct dasd_profile_info_t));
+		dasd_global_profile_reset();
+		dasd_stats_all_block_reset();
 		pr_info("The statistics have been reset\n");
 	} else
-		goto out_error;
+		goto out_parse_error;
 	kfree(buffer);
 	return user_len;
-out_error:
+out_parse_error:
+	rc = -EINVAL;
 	pr_warning("%s is not a supported value for /proc/dasd/statistics\n",
 		str);
+out_error:
 	kfree(buffer);
-	return -EINVAL;
+	return rc;
 #else
 	pr_warning("/proc/dasd/statistics: is not activated in this kernel\n");
 	return user_len;