Mike Fleetwood authored Jul 12, 2016 and Curtis Gedak committed Aug 06, 2016

GParted is already reading /proc/partitions to get whole disk device
names.  The file also contains the major, minor device number of every
partition.  Use this information to pre-populate the cache in the
BlockSpecial class.

    # cat /proc/partitions
    major minor  #blocks  name

       8        0   20971520 sda
       8        1     512000 sda1
       8        2   20458496 sda2
    ...
       9        3    1047552 md3
     259        2     262144 md3p1
     259        3     262144 md3p2
    ...
     253        0   18317312 dm-0
     253        1    2097152 dm-1
     253        2    8383872 dm-2
     253        3    1048576 dm-3

Note that for Device-Mapper names (dm-*) the kernel is not using the
canonical user space names (mapper/*).  There is no harm in
pre-populating the cache with these names and will help if tools report
them too.  It is just that for DMRaid, LVM and LUKS, GParted uses the
canonical /dev/mapper/* names so will still have to call stat() once for
each such name.

For plain disks (sd*) and Linux Software RAID arrays (md*) the kernel
name is the common user space name too, therefore matches what GParted
uses and pre-populating does avoid calling stat() at all for these
names.

Bug 767842 - File system usage missing when tools report alternate block
             device names