[systemd-devel] systemd mucking with partition tables ( was: bug#25756: Problems using "parted ... print" on nvme devices )

[Lennart Poettering]

On Wed, 19.04.17 13:59, Phil Susi (psusi at ubuntu.com) wrote:

> On 4/19/2017 12:17 PM, Lennart Poettering wrote:
> > This isn't precisely new functionality, it has been doing that since
> > years. It will synthesize "change" udev events when a process closes a block
> > device after writing, so that the changed superblock/partition
> > information is properly propagated to clients.
> > 
> > Also note that parted never was in the business of retriggering block
> > devices through sysfs/udev (i.e. echoing "change" into a "uevents"
> > file in sysfs), only udev ever did that so far, and I am pretty sure
> > that should stay that way.
> 
> What?  The kernel must generate the event as otherwise systemd has no
> idea that a process on the system closed its handle to the device, and
> so would not know when it should trigger them.  Or do you mean that the
> kernel only triggers on the main device, and udev now synthesizes events
> on the partitions?

The kernel generates inotify IN_CLOSED_WRITE events, and udev then
retriggers the device.

Lennart

-- 
Lennart Poettering, Red Hat