svn commit: r276123 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Xin Li]

Hi, Steven,

On 12/30/14 22:01, Steven Hartland wrote:
> 
> On 31/12/2014 02:12, Xin Li wrote:
>> On 12/23/14 01:31, Steven Hartland wrote:
>>> Author: smh
>>> Date: Tue Dec 23 09:31:24 2014
>>> New Revision: 276123
>>> URL: https://svnweb.freebsd.org/changeset/base/276123
>>>
>>> Log:
>>>    Always sync the global ZFS config cache to reflect the new mosconfig
>>>       This fixes out of date zpool.cache for root pools, which can
>>> cause issues
>>>    such as confusion of zdb etc.
>>>       MFC after:    1 month
>>>
>>> Modified:
>>>    head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_config.c
>>>
>>> Modified:
>>> head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_config.c
>>> ==============================================================================
>>>
>>> ---
>>> head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_config.c   
>>> Tue Dec 23 08:51:30 2014    (r276122)
>>> +++
>>> head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_config.c   
>>> Tue Dec 23 09:31:24 2014    (r276123)
>>> @@ -536,8 +536,7 @@ spa_config_update(spa_t *spa, int what)
>>>       /*
>>>        * Update the global config cache to reflect the new mosconfig.
>>>        */
>>> -    if (!spa->spa_is_root)
>>> -        spa_config_sync(spa, B_FALSE, what != SPA_CONFIG_UPDATE_POOL);
>>> +    spa_config_sync(spa, B_FALSE, what != SPA_CONFIG_UPDATE_POOL);
>>>         if (what == SPA_CONFIG_UPDATE_POOL)
>>>           spa_config_update(spa, SPA_CONFIG_UPDATE_VDEVS);
>> It seems like that this change breaks systems where not all pools are
>> available (e.g. some of pools are encrypted) at boot time, by removing
>> all these pools from the cache file.
>>
>> As a result, on the next boot, these pools would not be imported even
>> when the devices are available (geli attached), and reverting this
>> change would restore the system to its previous behavior.
>>
>> Perhaps it have exposed an existing bug?
> 
> I've managed to reproduce this here with mdX backed test pools, and
> looking into it this is due to spa_config_sync:
> 
>                         /*
>                          * Skip over our own pool if we're about to remove
>                          * ourselves from the spa namespace or any pool
> that
>                          * is readonly. Since we cannot guarantee that a
>                          * readonly pool would successfully import upon
> reboot,
>                          * we don't allow them to be written to the
> cache file.
>                          */
>                         if ((spa == target && removing) ||
>                             !spa_writeable(spa)) {
>                                 continue;
>                         }
> 
> This was added by upstream:
> https://github.com/illumos/illumos-gate/commit/fb02ae025247e3b662600e5a9c1b4c33ecab7d72
> 
> https://www.illumos.org/issues/3639
> 
> It seems the desired behavior was to exclude read only pools, to prevent
> them being mounted writable on reboot, but the check is too wide and
> also excludes unavailable pools too.
> 
> The attached patch corrects the test to only check writable on active
> pools so I believe should fix the issue your seeing.
> 
> If you can test it and lmk that would be great.

This is an improvement (the attaching of pool is now working) but the
cached configuration is somewhat corrupted, it shows many lines of
vdev_stats[] contents.

I'll take a look at the code tomorrow and see if I can do some
instruments and possibly figure out the underlying issue.

Cheers,