Re: ramdisk problems in 4.0-rc1? (was Re: [PATCH 1/4] xfs/104: log size too small for 4k sector drives)

[Boaz Harrosh <boaz@plexistor.com>]

On 02/27/2015 02:58 AM, Dave Chinner wrote:
<>
>>
>> Sigh, thanks Dave. Yes you are correct my patch enabled the
>> udev events, as part of fixing ramdisk with partitions.
>> This is because if you do not enable them then mount by UUID
>> and all sort of lsblk and friends do not work.
> 
> Sure, that's what the gendisk abstraction just you. But why am I
> seeing random partition probes on a ramdisk that *isn't using
> partitions*?
> 

Yes, There should be the one new event on create (modprobe or
mknod) which was not there before. Perhaps it triggers a systemd
process that never used to run before. (And is now sitting there
and making a mess)

<>
>> It looks like the system anticipates that ramdisk "should
>> not have these events"
> 
> Right, but not because it's a ramdisk. Those events should not be
> occurring because I'm not creating or destroying devices, I'm not
> changing partition tables, I'm not resizing ramdisks or partitions,
> and so on. I'm simply mkfs'ing, mounting and unmounting filesystems
> on the ramdisks - nothing should be generating device based udev
> events...
> 
> Finding the trigger that is causing these events will tell us what
> the bug is - 

> restricting the config won't help, especially as DAX
> will *always* be enabled on my test machines as it's something
> needed in my test matrix.

No the "if DAX" is for the 4k thing. The enablement of the uevents is
with a new "part_show" module parameter (See patch-1).

> I'm not sure how to go about finding that
> trigger right now and as such I won't really have time to look at it
> until after lsfmm/vault...
> 

I'll try to reproduce this here. What Fedora version do I need?

> Cheers,
> Dave.
> 

Thanks
Boaz