Diskmount

Project born out of despair and frustration.. Desperacy searching for simple automatic disk mounter and frustration manually mounting and unmounting disks. Due to above mentioned psychological condition and for sake of simplicity utility is POSIX compatible without any cumber auto-torture stuff.

Sibling projects

There are some sibling projects providing similar functionality but but non of them would simply mount devices into specified location automatically without pain. Closest one to match needs was simple usbmount, however i was urging for more deterministic and flexible mounts.

https://github.com/rbrito/usbmount https://github.com/storaged-project/udisks https://git.kernel.org/pub/scm/linux/storage/autofs/autofs.git/

Current approach

One way or another this approach is based on uevent kobject kernel notifications. Current approach uses udev and it's hooks to read events and pass them for mounting.

Build

Options

• WITH_UGID -- option enables uid/gid switching and specifying username/password when initializing mount directories.
• WITH_LIBBLKID -- enables linking with libblkid, enables extra disk properties resolution capabilities for augmenting kernel events. If something does not work with kernel evens libblkid is likely to fix it.
• EVHEAD_MAGIC -- specifies unique magic for coupling diskmount and diskmountd to "ensure" custom local events integrity.

Compile

   make

Build outputs two binaries:

• diskmount -- client utility, proxies disk events.
• diskmountd -- daemon service, performs disk mounting.

Configs

Configuration files are searched in few locations:

• local config -- ./diskmount.conf
• user config -- ~/.config/diskmount/config
• global config -- /etc/diskmount.conf

Setup

Service uses configuration file to determine mount points and options:

   /dev/sdb1                  /mnt/disk-one
   DEV=/dev/sdb1              /tmp/read-only      -       ro
   LABEL=LaCie                /media/LaCie
   SERIAL=0EC125605221692E    /mnt/dummy          vfat
   UUID=2920-50BC             /mnt/my-drive       ntfs    rw,relatime
   PARTUUID=00014c47-01       /media/other

Structure is pretty much strait forward, similar to one used in fstab: what to mount, where to mount, partition file system, mount options.

There are main keywords to identify source mount device:

• DEV -- by device file (no keyword also means device name).
• LABEL -- by disk label.
• SERIAL -- by disk serial number.
• UUID -- by FS UUID.
• PARTUUID -- by partition UUID.

Running

Disk mount service automatically starts listening for NL (libudev or kernel) events as well as custom events on local UNIX domain socket. If libudev is not available it will start listening for kernel events.

Using libudev events

Start diskmountd service will listen to udev events:

   diskmountd

Using kernel uevents

If libudev is missing diskmountd will automatically fallback to kernel uevent approach. However it is possible to force listening to kernel events:

   diskmountd -k

External events

This is totally optional and not too useful mechanism in standard scenarios to trigger mount; all the events are captured via netlink.

Start diskmountd service:

   diskmountd

Setup udev rule to forward events:

   $ cat /etc/udev/rules.d/90-diskmount.rules
   ENV{DEVTYPE}=="partition", RUN+="/usr/bin/diskmount"

Or trigger manually:

   ACTION=add DEVNAME=/dev/sdb1 ID_FS_TYPE=ntfs /usr/bin/diskmount

Monitoring

Printing disk mount config, mount tab and captured events:

   diskmountd -m