disk-linux branch: Fix a bug in the disk plugin.

When `{read,write}-sectors' hit the 32 bit boundary, `atoi' would always return
LONG_MAX, resulting in the same counter-value being logged over and over again,
resulting in zero-entries in the RRD file.
Thanks to James Valente for reporting this bug and providing much debugging
information :)

diff --git a/src/disk.c b/src/disk.c
index 6aefbc7..ca3531e 100644 (file)
--- a/src/disk.c
+++ b/src/disk.c
@@ -101,8 +101,8 @@ typedef struct diskstats
        /* This overflows in roughly 1361 year */
        unsigned int poll_count;
 
-       unsigned int read_sectors;
-       unsigned int write_sectors;
+       unsigned long long read_sectors;
+       unsigned long long write_sectors;
 
        unsigned long long read_bytes;
        unsigned long long write_bytes;
@@ -111,6 +111,7 @@ typedef struct diskstats
 } diskstats_t;
 
 static diskstats_t *disklist;
+static int min_poll_count;
 /* #endif KERNEL_LINUX */
 
 #elif HAVE_LIBKSTAT
@@ -143,7 +144,17 @@ static void disk_init (void)
 /* #endif HAVE_IOKIT_IOKITLIB_H */
 
 #elif KERNEL_LINUX
-       /* No init needed */
+       int step;
+       int heartbeat;
+
+       step = atoi (COLLECTD_STEP);
+       heartbeat = atoi (COLLECTD_HEARTBEAT);
+
+       assert (step > 0);
+       assert (heartbeat >= step);
+
+       min_poll_count = 1 + (heartbeat / step);
+       DBG ("min_poll_count = %i;", min_poll_count);
 /* #endif KERNEL_LINUX */
 
 #elif HAVE_LIBKSTAT
@@ -219,6 +230,9 @@ static void disk_submit (char *disk_name,
                                write_time) >= BUFSIZE)
                return;
 
+       DBG ("disk_name = %s; buf = %s;",
+                       disk_name, buf);
+
        plugin_submit (MODULE_NAME, disk_name, buf);
 }
 
@@ -431,17 +445,17 @@ static void disk_read (void)
        int major = 0;
        int minor = 0;
 
-       unsigned int read_sectors;
-       unsigned int write_sectors;
-
-       unsigned long long read_count    = 0;
-       unsigned long long read_merged   = 0;
-       unsigned long long read_bytes    = 0;
-       unsigned long long read_time     = 0;
-       unsigned long long write_count   = 0;
-       unsigned long long write_merged  = 0;
-       unsigned long long write_bytes   = 0;
-       unsigned long long write_time    = 0;
+       unsigned long long read_sectors  = 0ULL;
+       unsigned long long write_sectors = 0ULL;
+
+       unsigned long long read_count    = 0ULL;
+       unsigned long long read_merged   = 0ULL;
+       unsigned long long read_bytes    = 0ULL;
+       unsigned long long read_time     = 0ULL;
+       unsigned long long write_count   = 0ULL;
+       unsigned long long write_merged  = 0ULL;
+       unsigned long long write_bytes   = 0ULL;
+       unsigned long long write_time    = 0ULL;
        int is_disk = 0;
 
        diskstats_t *ds, *pre_ds;
@@ -495,17 +509,17 @@ static void disk_read (void)
                {
                        /* Kernel 2.6, Partition */
                        read_count    = atoll (fields[3]);
-                       read_sectors  = atoi  (fields[4]);
+                       read_sectors  = atoll (fields[4]);
                        write_count   = atoll (fields[5]);
-                       write_sectors = atoi  (fields[6]);
+                       write_sectors = atoll (fields[6]);
                }
                else if (numfields == (14 + fieldshift))
                {
                        read_count  =  atoll (fields[3 + fieldshift]);
                        write_count =  atoll (fields[7 + fieldshift]);
 
-                       read_sectors  = atoi (fields[5 + fieldshift]);
-                       write_sectors = atoi (fields[9 + fieldshift]);
+                       read_sectors  = atoll (fields[5 + fieldshift]);
+                       write_sectors = atoll (fields[9 + fieldshift]);
 
                        if ((fieldshift == 0) || (minor == 0))
                        {
@@ -518,19 +532,20 @@ static void disk_read (void)
                }
                else
                {
+                       DBG ("numfields = %i; => unknown file format.", numfields);
                        continue;
                }
 
-
-               if (read_sectors >= ds->read_sectors)
-                       ds->read_bytes += 512 * (read_sectors - ds->read_sectors);
+               /* If the counter wraps around, it's only 32 bits.. */
+               if (read_sectors < ds->read_sectors)
+                       ds->read_bytes += 512 * ((0xFFFFFFFF - ds->read_sectors) + read_sectors);
                else
-                       ds->read_bytes += 512 * ((UINT_MAX - ds->read_sectors) + read_sectors);
+                       ds->read_bytes += 512 * (read_sectors - ds->read_sectors);
 
-               if (write_sectors >= ds->write_sectors)
-                       ds->write_bytes += 512 * (write_sectors - ds->write_sectors);
+               if (write_sectors < ds->write_sectors)
+                       ds->write_bytes += 512 * ((0xFFFFFFFF - ds->write_sectors) + write_sectors);
                else
-                       ds->write_bytes += 512 * ((UINT_MAX - ds->write_sectors) + write_sectors);
+                       ds->write_bytes += 512 * (write_sectors - ds->write_sectors);
 
                ds->read_sectors  = read_sectors;
                ds->write_sectors = write_sectors;
@@ -539,11 +554,18 @@ static void disk_read (void)
 
                /* Don't write to the RRDs if we've just started.. */
                ds->poll_count++;
-               if (ds->poll_count <= 6)
+               if (ds->poll_count <= min_poll_count)
+               {
+                       DBG ("(ds->poll_count = %i) <= (min_poll_count = %i); => Not writing.",
+                                       ds->poll_count, min_poll_count);
                        continue;
+               }
 
                if ((read_count == 0) && (write_count == 0))
+               {
+                       DBG ("((read_count == 0) && (write_count == 0)); => Not writing.");
                        continue;
+               }
 
                if (is_disk)
                        disk_submit (disk_name, read_count, read_merged, read_bytes, read_time,