1092308 - backport diskio device filtering

Backported from:

commit 5be210c90870ff6bab193d497d401b92c1d50db9

Author: Jan Safranek <jsafranek@users.sourceforge.net>

Date:   Thu Mar 6 13:26:30 2014 +0100

    CHANGES: snmpd: add new snmpd.conf option 'diskio' to monitor only selected disks.

    On machines with thousands of block devices, parsing /proc/diskstats is really

    slow. The new option enables monitoring of selected devices, saving lot of CPU

    time.

diff -up net-snmp-5.7.2/agent/mibgroup/ucd-snmp/diskio.c.test net-snmp-5.7.2/agent/mibgroup/ucd-snmp/diskio.c

--- net-snmp-5.7.2/agent/mibgroup/ucd-snmp/diskio.c.test	2012-10-10 00:28:58.000000000 +0200

+++ net-snmp-5.7.2/agent/mibgroup/ucd-snmp/diskio.c	2015-06-18 15:14:57.164891695 +0200

@@ -27,11 +27,18 @@

 #include <math.h>

+#if defined (linux)

+/* for stat() */

+#include <ctype.h>

+#include <sys/stat.h>

+#endif

+

 #include <net-snmp/net-snmp-includes.h>

 #include <net-snmp/agent/net-snmp-agent-includes.h>

 #include "util_funcs/header_simple_table.h"

+#include "struct.h"

 /*

  * include our .h file 

  */

@@ -95,6 +102,66 @@ static int ps_numdisks;			/* number of d

 #if defined (linux)

 #define DISKIO_SAMPLE_INTERVAL 5

 void devla_getstats(unsigned int regno, void * dummy);

+static void diskio_parse_config_disks(const char *token, char *cptr);

+static void diskio_free_config(void);

+static int get_sysfs_stats(void);

+

+struct diskiopart {

+    char            syspath[STRMAX];	/* full stat path */

+    char            name[STRMAX];	/* name as provided */

+    char            shortname[STRMAX];	/* short name for output */

+    int             major;

+    int             minor;

+};

+

+static int             numdisks;

+static int             maxdisks = 0;

+static struct diskiopart *disks;

+

+#define DISK_INCR 2

+

+typedef struct linux_diskio

+{

+    int major;

+    int  minor;

+    unsigned long  blocks;

+    char name[256];

+    unsigned long  rio;

+    unsigned long  rmerge;

+    unsigned long  rsect;

+    unsigned long  ruse;

+    unsigned long  wio;

+    unsigned long  wmerge;

+    unsigned long  wsect;

+    unsigned long  wuse;

+    unsigned long  running;

+    unsigned long  use;

+    unsigned long  aveq;

+} linux_diskio;

+

+/* disk load averages */

+typedef struct linux_diskio_la

+{

+    unsigned long use_prev;

+    double la1, la5, la15;

+} linux_diskio_la;

+

+typedef struct linux_diskio_header

+{

+    linux_diskio* indices;

+    int length;

+    int alloc;

+} linux_diskio_header;

+

+typedef struct linux_diskio_la_header

+{

+    linux_diskio_la * indices;

+    int length;

+} linux_diskio_la_header;

+

+static linux_diskio_header head;

+static linux_diskio_la_header la_head;

+

 #endif /* linux */

 #if defined (darwin)

@@ -228,6 +295,8 @@ init_diskio(void)

     devla_getstats(0, NULL);

     /* collect LA data regularly */

     snmp_alarm_register(DISKIO_SAMPLE_INTERVAL, SA_REPEAT, devla_getstats, NULL);

+    snmpd_register_config_handler("diskio", diskio_parse_config_disks,

+        diskio_free_config, "path | device");

 #endif

@@ -870,49 +939,134 @@ var_diskio(struct variable * vp,

 #ifdef linux

-#define DISK_INCR 2

-

-typedef struct linux_diskio

+static void

+diskio_free_config()

+ {

+    if (la_head.length) {

+        /* reset any usage stats, we may get different list of devices from config */

+        free(la_head.indices);

+        la_head.length = 0;

+        la_head.indices = NULL;

+    }

+    if (numdisks > 0) {

+        int i;

+        head.length = 0;

+        numdisks = 0;

+        for (i = 0; i < maxdisks; i++) {    /* init/erase disk db */

+            disks[i].syspath[0] = 0;

+            disks[i].name[0] = 0;

+            disks[i].shortname[0] = 0;

+            disks[i].major = -1;

+            disks[i].minor = -1;

+        }

+    }

+}

+static int

+disk_exists(char *path) 

 {

-    int major;

-    int  minor;

-    unsigned long  blocks;

-    char name[256];

-    unsigned long  rio;

-    unsigned long  rmerge;

-    unsigned long  rsect;

-    unsigned long  ruse;

-    unsigned long  wio;

-    unsigned long  wmerge;

-    unsigned long  wsect;

-    unsigned long  wuse;

-    unsigned long  running;

-    unsigned long  use;

-    unsigned long  aveq;

-} linux_diskio;

+    int index;

+    for(index = 0; index < numdisks; index++) {

+        DEBUGMSGTL(("ucd-snmp/disk", "Checking for %s. Found %s at %d\n", path, disks[index].syspath, index));

+        if(strcmp(path, disks[index].syspath) == 0) {

+            return index;

+        }

+    }

+    return -1;

+}

-/* disk load averages */

-typedef struct linux_diskio_la

-{

-    unsigned long use_prev;

-    double la1, la5, la15;

-} linux_diskio_la;

+static void

+add_device(char *path, int addNewDisks ) 

+ {

+    int index;

+    char device[STRMAX];

+    char syspath[STRMAX];

+    char *basename;

+    struct stat stbuf;

-typedef struct linux_diskio_header

-{

-    linux_diskio* indices;

-    int length;

-    int alloc;

-} linux_diskio_header;

+    if (!path || !strcmp(path, "none")) {

+        DEBUGMSGTL(("ucd-snmp/diskio", "Skipping null path device (%s)\n", path));

+        return;

+    }

+    if (numdisks == maxdisks) {

+        if (maxdisks == 0) {

+            maxdisks = 50;

+            disks = malloc(maxdisks * sizeof(struct diskiopart));

+            if (!disks) {

+                config_perror("malloc failed for new disko allocation.");

+	            netsnmp_config_error("\tignoring:  %s", path);

+                return;

+            }

+            memset(disks, 0, maxdisks * sizeof(struct diskiopart));

+        } else {

+            maxdisks *= 2;

+            disks = realloc(disks, maxdisks * sizeof(struct diskiopart));

+            if (!disks) {

+                config_perror("malloc failed for new disko allocation.");

+	            netsnmp_config_error("\tignoring:  %s", path);

+                return;

+            }

+            memset(disks + maxdisks/2, 0, maxdisks/2 * sizeof(struct diskiopart));

+        }

+    }

-typedef struct linux_diskio_la_header

-{

-    linux_diskio_la * indices;   

-    int length;

-} linux_diskio_la_header;

+    /* first find the path for this device */

+    device[0]='\0';

+    if ( *path != '/' ) {

+        strlcpy(device, "/dev/", STRMAX - 1 );

+    }

+    strncat(device, path, STRMAX - 1 );

+

+    /* check for /dev existence */

+    if ( stat(device,&stbuf)!=0 ) { /* ENOENT */

+        config_perror("diskio path does not exist.");

+        netsnmp_config_error("\tignoring:  %s", path);

+        return;

+    }

+    else if ( ! S_ISBLK(stbuf.st_mode) ) { /* ENODEV */

+        config_perror("diskio path is not a device.");

+        netsnmp_config_error("\tignoring:  %s", path);

+        return;

+    }

-static linux_diskio_header head;

-static linux_diskio_la_header la_head;

+    /* either came with a slash or we just put one there, so the following always works */

+    basename = strrchr(device, '/' )+1;

+    /* construct a sys path using the device numbers to avoid having to disambiguate the various text forms */

+    snprintf( syspath, STRMAX - 1, "/sys/dev/block/%d:%d/stat", major(stbuf.st_rdev), minor(stbuf.st_rdev) );

+    DEBUGMSGTL(("ucd-snmp/diskio", " monitoring sys path (%s)\n", syspath));

+

+    index = disk_exists(syspath);

+

+    if(index == -1 && addNewDisks){

+        /* The following buffers are cleared above, no need to add '\0' */

+        strlcpy(disks[numdisks].syspath, syspath, sizeof(disks[numdisks].syspath) - 1);

+        strlcpy(disks[numdisks].name, path, sizeof(disks[numdisks].name) - 1);

+        strlcpy(disks[numdisks].shortname, basename, sizeof(disks[numdisks].shortname) - 1);

+        disks[numdisks].major = major(stbuf.st_rdev);

+        disks[numdisks].minor = minor(stbuf.st_rdev);

+        numdisks++;  

+    }

+}

+

+static void 

+diskio_parse_config_disks(const char *token, char *cptr)

+ {

+#if HAVE_FSTAB_H || HAVE_GETMNTENT || HAVE_STATFS

+    char path[STRMAX];

+

+

+    /*

+     * read disk path (eg, /1 or /usr) 

+     */

+    copy_nword(cptr, path, sizeof(path));

+

+    /* TODO: we may include regular expressions in future */

+    /*

+     * check if the disk already exists, if so then modify its

+     * parameters. if it does not exist then add it

+     */

+    add_device(path, 1);

+#endif /* HAVE_FSTAB_H || HAVE_GETMNTENT || HAVE_STATFS */

+}

 void devla_getstats(unsigned int regno, void * dummy) {

@@ -976,6 +1130,47 @@ int is_excluded(const char *name)

     return 0;

 }

+static int get_sysfs_stats()

+{

+    int i;

+    char buffer[1024];

+

+    head.length  = 0;

+

+    for(i = 0; i < numdisks; i++) {

+        FILE *f = fopen(disks[i].syspath, "r");

+        if ( f == NULL ) {

+            DEBUGMSGTL(("ucd-snmp/diskio", "Can't open %s, skipping", disks[i].syspath));

+            continue;

+        }

+        if (fgets(buffer, sizeof(buffer), f) == NULL) {

+            DEBUGMSGTL(("ucd-snmp/diskio", "Can't read %s, skipping", disks[i].syspath));

+            fclose(f);

+            continue;

+        }

+

+        linux_diskio* pTemp;

+        if (head.length == head.alloc) {

+            head.alloc += DISK_INCR;

+            head.indices = (linux_diskio *) realloc(head.indices, head.alloc*sizeof(linux_diskio));

+        }

+        pTemp = &head.indices[head.length];

+        pTemp->major = disks[i].major;

+        pTemp->minor = disks[i].minor;

+        strlcpy( pTemp->name, disks[i].shortname, sizeof(pTemp->name) - 1 );

+        if (sscanf (buffer, "%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu\n",

+                &pTemp->rio, &pTemp->rmerge, &pTemp->rsect, &pTemp->ruse,

+                &pTemp->wio, &pTemp->wmerge, &pTemp->wsect, &pTemp->wuse,

+                &pTemp->running, &pTemp->use, &pTemp->aveq) != 11)

+            sscanf (buffer, "%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu%*[ \n\t]%lu\n",

+                &pTemp->rio, &pTemp->rsect,

+                &pTemp->wio, &pTemp->wsect);

+        head.length++;

+        fclose(f);

+    }

+    return 0;

+}

+

 static int

 getstats(void)

 {

@@ -995,6 +1189,14 @@ getstats(void)

     memset(head.indices, 0, head.alloc*sizeof(linux_diskio));

+    if (numdisks>0) {

+        /* 'diskio' configuration is used - go through the whitelist only and

+         * read /sys/dev/block/xxx */

+        cache_time = now;

+        return get_sysfs_stats();

+    }

+    /* 'diskio' configuration is not used - report all devices */

+

     /* Is this a 2.6 kernel? */

     parts = fopen("/proc/diskstats", "r");

     if (parts) {

@@ -1111,13 +1313,22 @@ var_diskio(struct variable * vp,

       long_ret = head.indices[indx].wio & 0xffffffff;

       return (u_char *) & long_ret;

     case DISKIO_LA1:

-      long_ret = la_head.indices[indx].la1;

+      if (la_head.length > indx)

+          long_ret = la_head.indices[indx].la1;

+      else

+          long_ret = 0;

       return (u_char *) & long_ret;

     case DISKIO_LA5:

-      long_ret = la_head.indices[indx].la5;

+      if (la_head.length > indx)

+          long_ret = la_head.indices[indx].la5;

+      else

+          long_ret = 0;

       return (u_char *) & long_ret;

     case DISKIO_LA15:

-      long_ret = la_head.indices[indx].la15;

+      if (la_head.length > indx)

+          long_ret = la_head.indices[indx].la15;

+      else

+          long_ret = 0;

       return (u_char *) & long_ret;

     case DISKIO_NREADX:

       *var_len = sizeof(struct counter64);

diff -up net-snmp-5.7.2/man/snmpd.conf.5.def.test net-snmp-5.7.2/man/snmpd.conf.5.def

--- net-snmp-5.7.2/man/snmpd.conf.5.def.test	2015-06-18 15:13:31.249470179 +0200

+++ net-snmp-5.7.2/man/snmpd.conf.5.def	2015-06-18 15:16:45.481423115 +0200

@@ -715,6 +715,15 @@ e.g. "loop0"

 .IP "diskio_exclude_ram yes"

 Excludes all LInux ramdisk block devices, whose names start with "ram", e.g.

 "ram0"

+.PP

+On Linux systems, it is possible to report only explicitly whitelisted

+devices. It may take significant amount of time to process diskIOTable data

+on systems with tens of thousands of block devices and whitelisting only the

+important ones avoids large CPU consumption.

+.IP "diskio <device>"

+Enables whitelisting of devices and adds the device to the whitelist. Only

+explicitly whitelisted devices will be reported. This option may be used

+multiple times.

 .SS System Load Monitoring

 This requires that the agent was built with support for either the

 \fIucd\-snmp/loadave\fR module or the \fIucd\-snmp/memory\fR module

commit 59f9f3387dab4238114804a0be9e4c15667d868c

Author: Jan Safranek <jsafranek@users.sourceforge.net>

Date:   Fri Jun 19 09:29:06 2015 +0200

    Fixed memory leak on realloc failure.

    Found by Coverity.

diff --git a/agent/mibgroup/ucd-snmp/diskio.c b/agent/mibgroup/ucd-snmp/diskio.c

index f04d5c5..58163d8 100644

--- a/agent/mibgroup/ucd-snmp/diskio.c

+++ b/agent/mibgroup/ucd-snmp/diskio.c

@@ -405,13 +405,17 @@ add_device(char *path, int addNewDisks )

             }

             memset(disks, 0, maxdisks * sizeof(struct diskiopart));

         } else {

+            struct diskiopart *newdisks;

             maxdisks *= 2;

-            disks = realloc(disks, maxdisks * sizeof(struct diskiopart));

-            if (!disks) {

+            newdisks = realloc(disks, maxdisks * sizeof(struct diskiopart));

+            if (!newdisks) {

+                free(disks);

+                disks = NULL;

                 config_perror("malloc failed for new disko allocation.");

 	            netsnmp_config_error("\tignoring:  %s", path);

                 return;

             }

+            disks = newdisks;

             memset(disks + maxdisks/2, 0, maxdisks/2 * sizeof(struct diskiopart));

         }

     }