bug#21272: partprobe does not wait for refresh of partition info

[Bjoern Eberth]

Hi all,

As the web bugtracker seems to be broken I write this mail.

I'm using parted 3.2. All this was tested running a Debian jessie release within a virtual machine on Windows 8.1 using VMware Workstation 11. /dev/sdb is an USB cardreader physically connected to the Windows 8.1 machine and looped to the virtual machine.

I was executing a script that does 'partprobe /dev/sdb' and immediatly after that 'dd of=/dev/sdb1 if=<something>'. The result is, that I get a regular file /dev/sdb1.

After some more investigation I found, that after executing partprobe the partition files got removed and readded to the system.

So running the script:

address@hidden:~# cat /tmp/test
partprobe /dev/sdb
while true; do
        ls -lad /dev/sdb1
done

results in:

address@hidden:~# /tmp/test
brw------- 1 root root 8, 17 Aug 15 16:39 /dev/sdb1
ls: cannot access /dev/sdb1: No such file or directory
ls: cannot access /dev/sdb1: No such file or directory
ls: cannot access /dev/sdb1: No such file or directory
ls: cannot access /dev/sdb1: No such file or directory
ls: cannot access /dev/sdb1: No such file or directory
brw------- 1 root root 8, 17 Aug 15 16:39 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 16:39 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 16:39 /dev/sdb1
[...]
brw-rw---- 1 root disk 8, 17 Aug 15 16:39 /dev/sdb1
brw-rw---- 1 root disk 8, 17 Aug 15 16:39 /dev/sdb1
brw-rw---- 1 root disk 8, 17 Aug 15 16:39 /dev/sdb1^C

All the above is happing in way less then a second after executing partprobe.
Thats a really odd behaviour.

Then I downgraded parted to version 2.2 and ran the test script again:
address@hidden:~# /tmp/test
brw------- 1 root root 8, 17 Aug 15 14:38 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 14:38 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 14:38 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 14:38 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 14:38 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 14:38 /dev/sdb1
brw------- 1 root root 8, 17 Aug 15 14:38 /dev/sdb1
[...]

brw-rw---- 1 root disk 8, 17 Aug 15 16:39 /dev/sdb1
brw-rw---- 1 root disk 8, 17 Aug 15 16:39 /dev/sdb1
brw-rw---- 1 root disk 8, 17 Aug 15 16:39 /dev/sdb1^C

This looks rather fine to me.

Is this a bug? Or is partprobe 3.2 just running much faster than partprobe 2.2 giving the kernel no time to reread the partition table? Or something else?

Kind regards,

Bjoern