Autoload of DM kernel targets?

Autoload of DM kernel targets?

[Andrei Borzenkov]

See as example https://bugzilla.opensuse.org/show_bug.cgi?id=983221

"non-standard" DM targets do not appear to be autoloaded (the problem
was hit with thin-pool, but it seems to apply to other targets as well).
"Common" targets (like linear) are provided by dm-mod which seems to be
autoloaded by virtue of /dev/mapper/control.

Is it expected and intentional? Or are users required to manually load
necessary modules on boot?

TIA

-andrei

Re: Autoload of DM kernel targets?

[NeilBrown]

[-- Attachment #1.1: Type: text/plain, Size: 1080 bytes --]

On Fri, Apr 21 2017, Andrei Borzenkov wrote:

> See as example https://bugzilla.opensuse.org/show_bug.cgi?id=983221
>
> "non-standard" DM targets do not appear to be autoloaded (the problem
> was hit with thin-pool, but it seems to apply to other targets as well).
> "Common" targets (like linear) are provided by dm-mod which seems to be
> autoloaded by virtue of /dev/mapper/control.
>
> Is it expected and intentional? Or are users required to manually load
> necessary modules on boot?
>
> TIA
>
> -andrei
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel

Does this patch fix it for you?

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 8f811dc8b3cc..d2c6a9a12d75 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -4400,3 +4400,4 @@ MODULE_PARM_DESC(no_space_timeout, "Out of data space queue IO timeout in second
 MODULE_DESCRIPTION(DM_NAME " thin provisioning target");
 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 MODULE_LICENSE("GPL");
+MODULE_ALIAS("dm-thin-pool");

NeilBrown

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]

[-- Attachment #2: Type: text/plain, Size: 0 bytes --]

Re: Autoload of DM kernel targets?

[Andrei Borzenkov]

[-- Attachment #1.1.1: Type: text/plain, Size: 1682 bytes --]

24.04.2017 07:05, NeilBrown пишет:
> On Fri, Apr 21 2017, Andrei Borzenkov wrote:
> 
>> See as example https://bugzilla.opensuse.org/show_bug.cgi?id=983221
>>
>> "non-standard" DM targets do not appear to be autoloaded (the problem
>> was hit with thin-pool, but it seems to apply to other targets as well).
>> "Common" targets (like linear) are provided by dm-mod which seems to be
>> autoloaded by virtue of /dev/mapper/control.
>>
>> Is it expected and intentional? Or are users required to manually load
>> necessary modules on boot?
>>
>> TIA
>>
>> -andrei
>>
>> --
>> dm-devel mailing list
>> dm-devel@redhat.com
>> https://www.redhat.com/mailman/listinfo/dm-devel
> 
> Does this patch fix it for you?
> 

I did not test it, because the problem (at least, this specific problem)
turned out a packaging problem - lvm checks for available targets before
it even tries to call into kernel, so this should not change anything.
But it needs path to modprobe that is detected during build. mkdprobe
was not present in build environment so lvm did not try to autoload
anything and immediately failed. Making sure to BuildRequire (package,
that provides) it fixed the problem.

> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index 8f811dc8b3cc..d2c6a9a12d75 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
> @@ -4400,3 +4400,4 @@ MODULE_PARM_DESC(no_space_timeout, "Out of data space queue IO timeout in second
>  MODULE_DESCRIPTION(DM_NAME " thin provisioning target");
>  MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
>  MODULE_LICENSE("GPL");
> +MODULE_ALIAS("dm-thin-pool");
> 
> NeilBrown
> 



[-- Attachment #1.2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

[-- Attachment #2: Type: text/plain, Size: 0 bytes --]

Re: Autoload of DM kernel targets?

[Mike Snitzer]

On Mon, Apr 24 2017 at 12:05am -0400,
NeilBrown <neilb@suse.com> wrote:

> On Fri, Apr 21 2017, Andrei Borzenkov wrote:
> 
> > See as example https://bugzilla.opensuse.org/show_bug.cgi?id=983221
> >
> > "non-standard" DM targets do not appear to be autoloaded (the problem
> > was hit with thin-pool, but it seems to apply to other targets as well).
> > "Common" targets (like linear) are provided by dm-mod which seems to be
> > autoloaded by virtue of /dev/mapper/control.
> >
> > Is it expected and intentional? Or are users required to manually load
> > necessary modules on boot?
> >
> > TIA
> >
> > -andrei
> >
> > --
> > dm-devel mailing list
> > dm-devel@redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> 
> Does this patch fix it for you?
> 
> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index 8f811dc8b3cc..d2c6a9a12d75 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
> @@ -4400,3 +4400,4 @@ MODULE_PARM_DESC(no_space_timeout, "Out of data space queue IO timeout in second
>  MODULE_DESCRIPTION(DM_NAME " thin provisioning target");
>  MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
>  MODULE_LICENSE("GPL");
> +MODULE_ALIAS("dm-thin-pool");
> 
> NeilBrown

The module is named "dm-thin-pool.ko", so I'm not following why that
patch would help.