Re: [PATCH v2] btrfs: fix endianness compatibility during the SB RW

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2018年02月13日 18:27, Anand Jain wrote:
> 
> 
> On 02/13/2018 05:01 PM, Qu Wenruo wrote:
>>
>>
>> On 2018年02月13日 11:00, Anand Jain wrote:
>>> Fixes the endianness bug in the fs_info::super_copy by using its
>>> btrfs_set_super...() function to set values in the SB, as these
>>> functions manage the endianness compatibility nicely.
>>>
>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>
>> Also went through all btrfs_super_block SETGET functions, greping using
>> \><member name>, seems that there are still some left here:
>>
>> fs/btrfs/sysfs.c:
>> In both btrfs_sectorsize_show() and btrfs_clone_alignment_show():
>>     return snprintf(buf, PAGE_SIZE, "%u\n",
>>             fs_info->super_copy->sectorsize);
>>
>> In btrfs_nodesize_show():
>>     return snprintf(buf, PAGE_SIZE, "%u\n",
>> fs_info->super_copy->nodesize);
> 
>  Oh. Thanks. Will fix. Maybe it's a good idea to add sysfs fixes
>  into a new patch.
> 
>> And what about cc this to stable kernel?
>> IIRC it's a very critical problem for btrfs.
>>
>> Maybe cc: stable@vger.kernel.org # v3.2+?
> 
>  Thanks for the suggestion. Will do. Any idea what if the patch which
>  applied on mainline ends up conflict on LTS, so write a separate patch
>  to stable?

In fact I'm not sure about this either.

But considering much of the offending code doesn't change since 2009, it
wouldn't cause much conflict IIRC.

Thanks,
Qu

> 
> Thanks, Anand
> 
> 
>> Thanks,
>> Qu
>>
>>> ---
>>> v1->v2: Update change log. Update $Subject.
>>>          Old:
>>>          [PATCH] btrfs: use set functions to update latest refs to
>>> the SB
>>>   fs/btrfs/transaction.c | 20 ++++++++++++--------
>>>   1 file changed, 12 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
>>> index 04f07144b45c..9220f004001c 100644
>>> --- a/fs/btrfs/transaction.c
>>> +++ b/fs/btrfs/transaction.c
>>> @@ -1722,19 +1722,23 @@ static void update_super_roots(struct
>>> btrfs_fs_info *fs_info)
>>>         super = fs_info->super_copy;
>>>   +    /* update latest btrfs_super_block::chunk_root refs */
>>>       root_item = &fs_info->chunk_root->root_item;
>>> -    super->chunk_root = root_item->bytenr;
>>> -    super->chunk_root_generation = root_item->generation;
>>> -    super->chunk_root_level = root_item->level;
>>> +    btrfs_set_super_chunk_root(super, root_item->bytenr);
>>> +    btrfs_set_super_chunk_root_generation(super,
>>> root_item->generation);
>>> +    btrfs_set_super_chunk_root_level(super, root_item->level);
>>>   +    /* update latest btrfs_super_block::root refs */
>>>       root_item = &fs_info->tree_root->root_item;
>>> -    super->root = root_item->bytenr;
>>> -    super->generation = root_item->generation;
>>> -    super->root_level = root_item->level;
>>> +    btrfs_set_super_root(super, root_item->bytenr);
>>> +    btrfs_set_super_generation(super, root_item->generation);
>>> +    btrfs_set_super_root_level(super, root_item->level);
>>> +
>>>       if (btrfs_test_opt(fs_info, SPACE_CACHE))
>>> -        super->cache_generation = root_item->generation;
>>> +        btrfs_set_super_cache_generation(super, root_item->generation);
>>>       if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
>>> -        super->uuid_tree_generation = root_item->generation;
>>> +        btrfs_set_super_uuid_tree_generation(super,
>>> +                             root_item->generation);
>>>   }
>>>     int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
>>>
>>
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