Fix disk IO data collection for LVM setups (and possibly others)

[ottmi]

The collection of disk IO stats doesn't work for my LVM setup:

root@nl:~# lsblk -l
NAME     MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINTS
sr0       11:0    1  368K  0 rom   
vda      252:0    0  4.5T  0 disk  
vda1     252:1    0    1M  0 part  
vda2     252:2    0  4.5T  0 part  
luks     253:0    0  4.5T  0 crypt 
vg0-root 253:1    0   50G  0 lvm   /
vg0-swap 253:2    0    4G  0 lvm   [SWAP]
vg0-home 253:3    0  4.5T  0 lvm   /home

root@nl:~# cat /proc/diskstats 
   7       0 loop0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   7       1 loop1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   7       2 loop2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   7       3 loop3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   7       4 loop4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   7       5 loop5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   7       6 loop6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   7       7 loop7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
  11       0 sr0 53 0 350 21 0 0 0 0 0 60 21 0 0 0 0 0 0
 252       0 vda 127738 6092 24792808 1318834 2440750 573137 67967912 3800408 0 1821416 5188906 0 0 0 0 168084 69664
 252       1 vda1 84 0 658 160 0 0 0 0 0 200 160 0 0 0 0 0 0
 252       2 vda2 127525 6092 24786751 1317794 2440750 573137 67967912 3800408 0 1820992 5118202 0 0 0 0 0 0
 253       0 dm-0 133551 0 24784964 1431684 2989115 0 67967912 11160832 0 1866872 12592516 0 0 0 0 0 0
 253       1 dm-1 33008 0 2346606 261696 2863983 0 28326984 10457368 0 1508368 10719064 0 0 0 0 0 0
 253       2 dm-2 452 0 12604 2268 1830 0 14640 7752 0 3244 10020 0 0 0 0 0 0
 253       3 dm-3 100018 0 22423214 1167836 110453 0 39626288 341248 0 378516 1509084 0 0 0 0 0 0

So basically, e.g. for /home it was looking for vg0-home in /proc/diskstats but that only has the dm-[0-3] entries. The modified version uses the major:minor to translate into the device-mapper entires via /etc/partitions. This should also work with non-LVM setups.

It also removes unnecessary IOPSRead and IOPSWrite in the initialization as this is repeated later in the loop

[ottmi]

It also removes unnecessary IOPSRead and IOPSWrite in the initialization as this is repeated later in the loop

Turns out that those were not unnecessary. I should have tested this before throwing it out last minute.. 53ca7e5 brings those back.

db50105 makes sure that mount points that are not block devices (e.g. NFS/SMB mounts) make it to the IOPS list.