label devices got removed after format

label devices got removed after format

[Stefan Priebe - Profihost AG]

Hi,

after doing mkfs.xfs -f /dev/bcache/by-label/mybcachelabel

/dev/bcache/by-label/mybcachelabel gots removed...

Only a reboot brings it back.

Stefan

Re: label devices got removed after format

[Kent Overstreet]

On Thu, Jul 11, 2013 at 11:43:22AM +0200, Stefan Priebe - Profihost AG wrote:
> Hi,
> 
> after doing mkfs.xfs -f /dev/bcache/by-label/mybcachelabel
> 
> /dev/bcache/by-label/mybcachelabel gots removed...
> 
> Only a reboot brings it back.
> 
> Stefan

Gabriel - I bet the uevent bcache is emitting is conflicting with the
name of an existing label uevent; there'll be a symlink for the
filesystem's label - for the same block device - so the mkfs could be
causing another uevent to be emitted overwriting our label.

Or maybe the conflict is a bit more subtle - anyways, you added the
label uevent code, think you might be able to figure it out?

Re: label devices got removed after format

[Stefan Priebe - Profihost AG]

Am 12.07.2013 um 03:28 schrieb Kent Overstreet <kmo-PEzghdH756F8UrSeD/g0lQ@public.gmane.org>:

> On Thu, Jul 11, 2013 at 11:43:22AM +0200, Stefan Priebe - Profihost AG wrote:
>> Hi,
>> 
>> after doing mkfs.xfs -f /dev/bcache/by-label/mybcachelabel
>> 
>> /dev/bcache/by-label/mybcachelabel gots removed...
>> 
>> Only a reboot brings it back.
>> 
>> Stefan
> 
> Gabriel - I bet the uevent bcache is emitting is conflicting with the
> name of an existing label uevent; there'll be a symlink for the
> filesystem's label - for the same block device - so the mkfs could be
> causing another uevent to be emitted overwriting our label.
No it always seems to happen if udev gets triggered. It also happens on manually executing udevadm trigger. 

Stefan--
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Re: label devices got removed after format

[Gabriel de Perthuis]

On Thu, 11 Jul 2013 18:28:06 -0700, Kent Overstreet wrote:
> On Thu, Jul 11, 2013 at 11:43:22AM +0200, Stefan Priebe - Profihost AG wrote:
>> Hi,
>> 
>> after doing mkfs.xfs -f /dev/bcache/by-label/mybcachelabel
>> 
>> /dev/bcache/by-label/mybcachelabel gots removed...
>> 
>> Only a reboot brings it back.
>> 
>> Stefan
> 
> Gabriel - I bet the uevent bcache is emitting is conflicting with the
> name of an existing label uevent; there'll be a symlink for the
> filesystem's label - for the same block device - so the mkfs could be
> causing another uevent to be emitted overwriting our label.

The uevent property is CACHED_LABEL, a name that shouldn't interfere
with the cached device's filesystem label.

> Or maybe the conflict is a bit more subtle - anyways, you added the
> label uevent code, think you might be able to figure it out?

I actually can't reproduce this; the link doesn't disappear.

Re: label devices got removed after format

[Stefan Priebe - Profihost AG]

Am 12.07.2013 12:33, schrieb Gabriel de Perthuis:
> On Thu, 11 Jul 2013 18:28:06 -0700, Kent Overstreet wrote:
>> On Thu, Jul 11, 2013 at 11:43:22AM +0200, Stefan Priebe - Profihost AG wrote:
>>> Hi,
>>>
>>> after doing mkfs.xfs -f /dev/bcache/by-label/mybcachelabel
>>>
>>> /dev/bcache/by-label/mybcachelabel gots removed...
>>>
>>> Only a reboot brings it back.
>>>
>>> Stefan
>>
>> Gabriel - I bet the uevent bcache is emitting is conflicting with the
>> name of an existing label uevent; there'll be a symlink for the
>> filesystem's label - for the same block device - so the mkfs could be
>> causing another uevent to be emitted overwriting our label.
> 
> The uevent property is CACHED_LABEL, a name that shouldn't interfere
> with the cached device's filesystem label.
> 
>> Or maybe the conflict is a bit more subtle - anyways, you added the
>> label uevent code, think you might be able to figure it out?
> 
> I actually can't reproduce this; the link doesn't disappear.

To me it happens alays when a udev event is triggered. It seems the
label isn't republished. To me the whole Folder /dev/bcache gets removed.

May i've used the wrong kernel patches on top of 3.10?

I have 2cd508a73e7f02b6d30bdbf9322d0b9c6e11a58e and
74ba1d388deb5d064414696f83578b0aade4685a

Stefan

Re: label devices got removed after format

[Gabriel de Perthuis]

On Fri, 12 Jul 2013 12:44:49 +0200, Stefan Priebe - Profihost AG wrote:
> Am 12.07.2013 12:33, schrieb Gabriel de Perthuis:
>> On Thu, 11 Jul 2013 18:28:06 -0700, Kent Overstreet wrote:
>>> On Thu, Jul 11, 2013 at 11:43:22AM +0200, Stefan Priebe - Profihost AG wrote:
>>>> Hi,
>>>>
>>>> after doing mkfs.xfs -f /dev/bcache/by-label/mybcachelabel
>>>>
>>>> /dev/bcache/by-label/mybcachelabel gots removed...
>>>>
>>>> Only a reboot brings it back.
>>>>
>>>> Stefan
>>>
> To me it happens alays when a udev event is triggered. It seems the
> label isn't republished. To me the whole Folder /dev/bcache gets removed.
> 
> May i've used the wrong kernel patches on top of 3.10?

After discussing this on IRC:

The Squeeze version of udev chokes on newlines in labels, to the point
that all the device's symlinks are removed; the uuid symlinks aren't
even involved in label uevents.
As a workaround, the latest commit in [1] strips endlines when setting
the label.

[1] https://github.com/g2p/linux/commits/v3.10%2Bbcache-for-3.11

Re: label devices got removed after format

[Kent Overstreet]

On Fri, Jul 12, 2013 at 11:40:56AM +0000, Gabriel de Perthuis wrote:
> On Fri, 12 Jul 2013 12:44:49 +0200, Stefan Priebe - Profihost AG wrote:
> > Am 12.07.2013 12:33, schrieb Gabriel de Perthuis:
> >> On Thu, 11 Jul 2013 18:28:06 -0700, Kent Overstreet wrote:
> >>> On Thu, Jul 11, 2013 at 11:43:22AM +0200, Stefan Priebe - Profihost AG wrote:
> >>>> Hi,
> >>>>
> >>>> after doing mkfs.xfs -f /dev/bcache/by-label/mybcachelabel
> >>>>
> >>>> /dev/bcache/by-label/mybcachelabel gots removed...
> >>>>
> >>>> Only a reboot brings it back.
> >>>>
> >>>> Stefan
> >>>
> > To me it happens alays when a udev event is triggered. It seems the
> > label isn't republished. To me the whole Folder /dev/bcache gets removed.
> > 
> > May i've used the wrong kernel patches on top of 3.10?
> 
> After discussing this on IRC:
> 
> The Squeeze version of udev chokes on newlines in labels, to the point
> that all the device's symlinks are removed; the uuid symlinks aren't
> even involved in label uevents.
> As a workaround, the latest commit in [1] strips endlines when setting
> the label.
> 
> [1] https://github.com/g2p/linux/commits/v3.10%2Bbcache-for-3.11

Thanks, applied.

Gabriel, would you mind sending me these patches with git format-patch
or git send-email? I didn't see this until last night :)

Re: label devices got removed after format

[Gabriel de Perthuis]

On Tue, 16 Jul 2013 14:37:56 -0700, Kent Overstreet wrote:
> On Fri, Jul 12, 2013 at 11:40:56AM +0000, Gabriel de Perthuis wrote:
>> The Squeeze version of udev chokes on newlines in labels, to the point
>> that all the device's symlinks are removed; the uuid symlinks aren't
>> even involved in label uevents.
>> As a workaround, the latest commit in [1] strips endlines when setting
>> the label.
>> 
>> [1] https://github.com/g2p/linux/commits/v3.10%2Bbcache-for-3.11
> 
> Thanks, applied.

Thanks.

> Gabriel, would you mind sending me these patches with git format-patch
> or git send-email? I didn't see this until last night :)

Ah, sorry.  I iterated those pushes a bit, so I didn't mind you
not picking it up right away, but I'll try to switch to more visible
email next time.