From: Sebastien Godard <sysstat@orange.fr>
Date: Sat, 11 Dec 2010 20:49:22 +0000 (+0100)
Subject: No longer assume that device-mapper major number is 253.
X-Git-Tag: v9.1.7~4
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4accbb2d37dc04dad87cdc4ffbf9021d10eadbf1;p=sysstat

No longer assume that device-mapper major number is 253.
Get the real number from /proc/devices file.

The sar, sadf and iostat commands used to assume that device-mapper
major number was 253. This happened to be false sometimes. So get
the real number from the /proc/devices file.

From Mike Coleman <tutufan@gmail.com> 04/10/2010:

The iostat program seems to assume that the major device number for
devmap will always be 253.  This doesn't seem to be an official
number, though, and I have a box where it actually ends up being 252,
which breaks 'iostat -N'.

It looks like this can be determined dynamically by looking at /proc/devices.
---

diff --git a/CHANGES b/CHANGES
index 04153df..c3aadac 100644
--- a/CHANGES
+++ b/CHANGES
@@ -11,6 +11,8 @@ xxxx/xx/xx: Version 9.1.7 - Sebastien Godard (sysstat <at> orange.fr)
 	  variable. nfsiostat default output is expressed in kB/s,
 	  unless this variable is set (in which case the output is
 	  expressed in blocks/s).
+	* No longer assume that device-mapper major number is 253.
+	  Get the real number from /proc/devices file.
 	* [Kenichi Okuyama]: Small change to sar manual page.
 	* sar manual page updated.
 	* Code cleaned.
diff --git a/common.c b/common.c
index 48c8368..8b1bdba 100644
--- a/common.c
+++ b/common.c
@@ -262,6 +262,38 @@ int get_sysfs_dev_nr(int display_partitions)
 	return dev;
 }
 
+/*
+ ***************************************************************************
+ * Read /proc/devices file and get device-mapper major number.
+ * If device-mapper entry is not found in file, use DEFAULT_DEMAP_MAJOR
+ * number.
+ *
+ * RETURNS:
+ * Device-mapper major number.
+ ***************************************************************************
+ */
+unsigned int get_devmap_major(void)
+{
+	FILE *fp;
+	char line[128];
+	unsigned int dm_major = DEFAULT_DEVMAP_MAJOR;
+
+	if ((fp = fopen(DEVICES, "r")) == NULL)
+		return dm_major;
+
+	while (fgets(line, 128, fp) != NULL) {
+
+		if (strstr(line, "device-mapper")) {
+			/* Read device-mapper major number */
+			sscanf(line, "%u", &dm_major);
+		}
+	}
+
+	fclose(fp);
+
+	return dm_major;
+}
+
 /*
  ***************************************************************************
  * Print banner.
diff --git a/common.h b/common.h
index 4d2651e..cf067a3 100644
--- a/common.h
+++ b/common.h
@@ -55,19 +55,20 @@
 #define SYSFS_TIME_IN_STATE	"cpufreq/stats/time_in_state"
 #define S_STAT			"stat"
 #define DEVMAP_DIR		"/dev/mapper"
+#define DEVICES			"/proc/devices"
 
-#define MAX_FILE_LEN	256
-#define MAX_PF_NAME	1024
-#define DEVMAP_MAJOR	253
-#define MAX_NAME_LEN	72
+#define MAX_FILE_LEN		256
+#define MAX_PF_NAME		1024
+#define DEFAULT_DEVMAP_MAJOR	253
+#define MAX_NAME_LEN		72
 
-#define NR_DISKS	4
+#define NR_DISKS		4
 
 /* Environment variables */
-#define ENV_TIME_FMT	"S_TIME_FORMAT"
-#define ENV_TIME_DEFTM	"S_TIME_DEF_TIME"
+#define ENV_TIME_FMT		"S_TIME_FORMAT"
+#define ENV_TIME_DEFTM		"S_TIME_DEF_TIME"
 
-#define DIGITS		"0123456789"
+#define DIGITS			"0123456789"
 
 
 /*
@@ -163,6 +164,8 @@ extern char *
 	device_name(char *);
 extern void
 	get_HZ(void);
+extern unsigned int
+	get_devmap_major(void);
 extern unsigned long long
 	get_interval(unsigned long long, unsigned long long);
 extern void
diff --git a/iostat.c b/iostat.c
index e2f98c7..745a530 100644
--- a/iostat.c
+++ b/iostat.c
@@ -61,6 +61,7 @@ int iodev_nr = 0;	/* Nb of devices and partitions found */
 int cpu_nr = 0;		/* Nb of processors on the machine */
 int dlist_idx = 0;	/* Nb of devices entered on the command line */
 int flags = 0;		/* Flag for common options and system state */
+unsigned int dm_major;	/* Device-mapper major number */
 
 long interval = 0;
 char timestamp[64];
@@ -678,7 +679,7 @@ void read_diskstats_stat(int curr)
 			}
 		}
 
-		if ((DISPLAY_DEVMAP_NAME(flags)) && (major == DEVMAP_MAJOR)) {
+		if ((DISPLAY_DEVMAP_NAME(flags)) && (major == dm_major)) {
 			/*
 			 * If the device is a device mapper device, try to get its
 			 * assigned name of its logical device.
@@ -1298,6 +1299,10 @@ int main(int argc, char **argv)
 		dlist_idx = 0;
 	}
 
+	if (DISPLAY_DEVMAP_NAME(flags)) {
+		dm_major = get_devmap_major();
+	}
+
 	/* Init structures according to machine architecture */
 	io_sys_init();
 
diff --git a/pr_stats.c b/pr_stats.c
index 86d9a8c..6fc7fad 100644
--- a/pr_stats.c
+++ b/pr_stats.c
@@ -37,6 +37,7 @@
 #endif
 
 extern unsigned int flags;
+extern unsigned int dm_major;
 extern int  dis;
 extern char timestamp[][TIMESTAMP_LEN];
 extern unsigned long avg_count;
@@ -823,7 +824,7 @@ __print_funct_t print_disk_stats(struct activity *a, int prev, int curr,
 		
 		dev_name = NULL;
 
-		if ((USE_PRETTY_OPTION(flags)) && (sdc->major == DEVMAP_MAJOR)) {
+		if ((USE_PRETTY_OPTION(flags)) && (sdc->major == dm_major)) {
 			dev_name = transform_devmapname(sdc->major, sdc->minor);
 		}
 
diff --git a/rndr_stats.c b/rndr_stats.c
index de0b840..58172fa 100644
--- a/rndr_stats.c
+++ b/rndr_stats.c
@@ -38,6 +38,7 @@
 static char *seps[] =  {"\t", ";"};
 
 extern unsigned int flags;
+extern unsigned int dm_major;
 
 /*
  ***************************************************************************
@@ -909,7 +910,7 @@ __print_funct_t render_disk_stats(struct activity *a, int isdb, char *pre,
 
 		dev_name = NULL;
 
-		if ((USE_PRETTY_OPTION(flags)) && (sdc->major == DEVMAP_MAJOR)) {
+		if ((USE_PRETTY_OPTION(flags)) && (sdc->major == dm_major)) {
 			dev_name = transform_devmapname(sdc->major, sdc->minor);
 		}
 
diff --git a/sadf.c b/sadf.c
index 77379e7..0d7b836 100644
--- a/sadf.c
+++ b/sadf.c
@@ -49,6 +49,7 @@ char *sccsid(void) { return (SCCSID); }
 long interval = -1, count = 0;
 
 unsigned int flags = 0;
+unsigned int dm_major;		/* Device-mapper major number */
 unsigned int format = 0;	/* Output format */
 
 /* File header */
@@ -1364,6 +1365,10 @@ int main(int argc, char **argv)
 		tm_end.tm_hour += 24;
 	}
 
+	if (USE_PRETTY_OPTION(flags)) {
+		dm_major = get_devmap_major();
+	}
+
 	/*
 	 * Display all the contents of the daily data file if the count parameter
 	 * was not set on the command line.
diff --git a/sar.c b/sar.c
index 69b9709..6a2f84c 100644
--- a/sar.c
+++ b/sar.c
@@ -50,6 +50,8 @@ long interval = -1, count = 0;
 int dis = TRUE;
 
 unsigned int flags = 0;
+unsigned int dm_major;	/* Device-mapper major number */
+
 char timestamp[2][TIMESTAMP_LEN];
 
 unsigned long avg_count = 0;
@@ -1273,6 +1275,10 @@ int main(int argc, char **argv)
 		usage(argv[0]);
 	}
 
+	if (USE_PRETTY_OPTION(flags)) {
+		dm_major = get_devmap_major();
+	}
+	
 	if (!count) {
 		/*
 		 * count parameter not set: Display all the contents of the file
diff --git a/xml_stats.c b/xml_stats.c
index df9fe14..096a997 100644
--- a/xml_stats.c
+++ b/xml_stats.c
@@ -36,6 +36,7 @@
 #endif
 
 extern unsigned int flags;
+extern unsigned int dm_major;
 
 /*
  ***************************************************************************
@@ -697,7 +698,7 @@ __print_funct_t xml_print_disk_stats(struct activity *a, int curr, int tab,
 		
 		dev_name = NULL;
 
-		if ((USE_PRETTY_OPTION(flags)) && (sdc->major == DEVMAP_MAJOR)) {
+		if ((USE_PRETTY_OPTION(flags)) && (sdc->major == dm_major)) {
 			dev_name = transform_devmapname(sdc->major, sdc->minor);
 		}