Re: [PATCH v3 00/13] btrfs: support read-write for subpage metadata

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

On 2021/4/6 上午10:31, Anand Jain wrote:
> On 05/04/2021 14:14, Qu Wenruo wrote:
>>
>>
>> On 2021/4/3 下午7:08, David Sterba wrote:
>>> On Thu, Mar 25, 2021 at 03:14:32PM +0800, Qu Wenruo wrote:
>>>> This patchset can be fetched from the following github repo, along with
>>>> the full subpage RW support:
>>>> https://github.com/adam900710/linux/tree/subpage
>>>>
>>>> This patchset is for metadata read write support.
>>>
>>>> Qu Wenruo (13):
>>>>    btrfs: add sysfs interface for supported sectorsize
>>>>    btrfs: use min() to replace open-code in btrfs_invalidatepage()
>>>>    btrfs: remove unnecessary variable shadowing in
>>>> btrfs_invalidatepage()
>>>>    btrfs: refactor how we iterate ordered extent in
>>>>      btrfs_invalidatepage()
>>>>    btrfs: introduce helpers for subpage dirty status
>>>>    btrfs: introduce helpers for subpage writeback status
>>>>    btrfs: allow btree_set_page_dirty() to do more sanity check on
>>>> subpage
>>>>      metadata
>>>>    btrfs: support subpage metadata csum calculation at write time
>>>>    btrfs: make alloc_extent_buffer() check subpage dirty bitmap
>>>>    btrfs: make the page uptodate assert to be subpage compatible
>>>>    btrfs: make set/clear_extent_buffer_dirty() to be subpage compatible
>>>>    btrfs: make set_btree_ioerr() accept extent buffer and to be subpage
>>>>      compatible
>>>>    btrfs: add subpage overview comments
>>>
>>> Moved from topic branch to misc-next.
>>>
>>
>> Note sure if it's too late, but I inserted the last comment patch into
>> the wrong location.
>>
>> In fact, there are 4 more patches to make
>
>
>> subpage metadata RW really work:
>
> I took some time to go through these patches, which are lined up for
> integration.
>
> With this set of patches that are being integrated, we don't yet
> support RW mount of filesystem if PAGESIZE > sectorsize as a whole.
> Subpage metadata RW support, how is it to be used in the production?

I'd say, without the ability to write subpage metadata, how would
subpage even be utilized in production environment?

> OR How is this supposed to be tested?

There are two ways:
- Craft some scripts to only do metadata operations without any data
   writes

- Wait for my data write support then run regular full test suites

I used to go method 1, but since in my local branch it's already full
subpage RW support, I'm doing method 2.

Although it exposes quite some bugs in data write path, it has been
quite a long time after last metadata related bug.

>
> OR should you just cleanup the title as preparatory patches to support
> subpage RW? It is confusing.

Well, considering this is the last patchset before full subpage RW, such
"preparatory" mention would be saved for next big function add.
(Thankfully, there is no such plan yet)

Thanks,
Qu

>
> Thanks, Anand
>
>
>> btrfs: make lock_extent_buffer_for_io() to be subpage compatible
>> btrfs: introduce submit_eb_subpage() to submit a subpage metadata page
>> btrfs: introduce end_bio_subpage_eb_writepage() function
>> btrfs: introduce write_one_subpage_eb() function
>>
>> Those 4 patches should be before the final comment patch.
>>
>> Should I just send the 4 patches in a separate series?
>>
>> Sorry for the bad split, it looks like multi-series patches indeed has
>> such problem...
>>
>> Thanks,
>> Qu
>