Re: [PATCH v4 00/30] btrfs: add data write support for subpage

[Anand Jain <anand.jain@oracle.com>]

On 8/6/21 5:50 pm, Qu Wenruo wrote:
> 
> 
> On 2021/6/8 下午5:45, Anand Jain wrote:
>>
>>
>> On 8/6/21 5:02 pm, Qu Wenruo wrote:
>>>
>>>
>>> On 2021/6/8 下午4:23, Anand Jain wrote:
>>>> On 31/5/21 4:50 pm, Qu Wenruo wrote:
>>>>> This huge patchset can be fetched from github:
>>>>> https://github.com/adam900710/linux/tree/subpage
>>>>>
>>>>> === Current stage ===
>>>>> The tests on x86 pass without new failure, and generic test group on
>>>>> arm64 with 64K page size passes except known failure and defrag group.
>>>>>
>>>>> For btrfs test group, all pass except compression/raid56/defrag.
>>>>>
>>>>> For anyone who is interested in testing, please apply this patch for
>>>>> btrfs-progs before testing.
>>>>> https://patchwork.kernel.org/project/linux-btrfs/patch/20210420073036.243715-1-wqu@suse.com/ 
>>>>>
>>>>>
>>>>>
>>>>> Or there will be too many false alerts.
>>>>>
>>>>> === Limitation ===
>>>>> There are several limitations introduced just for subpage:
>>>>> - No compressed write support
>>>>>    Read is no problem, but compression write path has more things
>>>>> left to
>>>>>    be modified.
>>>>>    Thus for current patchset, no matter what inode attribute or mount
>>>>>    option is, no new compressed extent can be created for subpage 
>>>>> case.
>>>>>
>>>>> - No inline extent will be created
>>>>>    This is mostly due to the fact that filemap_fdatawrite_range() will
>>>>>    trigger more write than the range specified.
>>>>>    In fallocate calls, this behavior can make us to writeback which 
>>>>> can
>>>>>    be inlined, before we enlarge the isize, causing inline extent 
>>>>> being
>>>>>    created along with regular extents.
>>>>>
>>>>> - No support for RAID56
>>>>>    There are still too many hardcoded PAGE_SIZE in raid56 code.
>>>>>    Considering it's already considered unsafe due to its write-hole
>>>>>    problem, disabling RAID56 for subpage looks sane to me.
>>>>>
>>>>> - No defrag support for subpage
>>>>>    The support for subpage defrag has already an initial version
>>>>>    submitted to the mail list.
>>>>>    Thus the correct support won't be included in this patchset.
>>>>>
>>>>
>>>> I am confused about what supports as of now?
>>>
>>>  From my latest subpage branch, everything work as expected.
>>>
>>> Defrag support is in another patchset, which can be applied
>>> independently.
>>>
>>>>   /sys/fs/btrfs/features/supported_sectorsizes
>>>
>>> [adam@arm-btrfs linux]$ uname -a
>>> Linux arm-btrfs 5.13.0-rc2-custom+ #5 SMP Tue Jun 1 16:11:41 CST 2021
>>> aarch64 GNU/Linux
>>> [adam@arm-btrfs linux]$ getconf PAGESIZE
>>> 65536
>>> [adam@arm-btrfs linux]$ cat /sys/fs/btrfs/features/supported_sectorsizes
>>> 4096 65536
>>>
>>> It still shows 4k as support sectorsize.
>>>
>>> What's your branch/HEAD? And are you using 64K page size?
>>>
>>
>>   I am on misc-next (which contains all these 30 patches). I don't see
>> subpages supported. Is there any patch I missed?
> 
> misc-next doesn't have full support yet.

Thanks for clarifying. I wasted too much time figuring out what's wrong 
with my setup. It wasn't explicit in the cover letter.
In that case, there is no regression in this set (plus with a bug fix 
patch as below). My Apologies to send this late:

  Tested-by: Anand Jain <anand.jain@oracle.com> [aarch64]

My test setup config:

Last commit on misc-next:
-----
aecab60cef1a (HEAD -> misc-next) btrfs: fix embarrassing bugs in 
find_next_dirty_byte()
3f3a096a4d67 (origin/misc-next) btrfs: remove total_data_size variable 
in btrfs_batch_insert_items()
-----

PLATFORM: Linux/aarch64
$ cpunr
32
$ cat /proc/meminfo | head -1
MemTotal: 16411904 kB
$ getconf PAGESIZE
65536

 >>> From my latest subpage branch, everything work as expected.

Let me try to apply on the current misc-next. I am targeting to test 
this with sectorsize=4096 on a pagesize=64K.  It will take some time as 
I need to get back to few other items as well.

Thanks, Anand


> 
> It lacks:
> - Relocation support
> - Bio split support
> - Various subpage specific fixes
> 
> Thus no subpage enabling patch.
> 
> Thanks,
> Qu
>>
>>   $ cat /sys/fs/btrfs/features/supported_sectorsizes
>> 65536
>>
>> Thanks, Anand
>>
>>> Thanks,
>>> Qu
>>>
>>>> list just the pagesize.
>>>>
>>>> Thanks, Anand
>>>>
>>>>
>>>>> === Patchset structure ===
>>>>>
>>>>> Patch 01~19:    Make data write path to be subpage compatible
>>>>> Patch 20~21:    Make data relocation path to be subpage compatible
>>>>> Patch 22~29:    Various fixes for subpage corner cases
>>>>> Patch 30:    Enable subpage data write
>>>>>
>>>>> === Changelog ===
>>>>> v2:
>>>>> - Rebased to latest misc-next
>>>>>    Now metadata write patches are removed from the series, as they are
>>>>>    already merged into misc-next.
>>>>>
>>>>> - Added new Reviewed-by/Tested-by/Reported-by tags
>>>>>
>>>>> - Use separate endio functions to subpage metadata write path
>>>>>
>>>>> - Re-order the patches, to make refactors at the top of the series
>>>>>    One refactor, the submit_extent_page() one, should benefit 4K page
>>>>>    size more than 64K page size, thus it's worthy to be merged early
>>>>>
>>>>> - New bug fixes exposed by Ritesh Harjani on Power
>>>>>
>>>>> - Reject RAID56 completely
>>>>>    Exposed by btrfs test group, which caused BUG_ON() for various
>>>>> sites.
>>>>>    Considering RAID56 is already not considered safe, it's better to
>>>>>    reject them completely for now.
>>>>>
>>>>> - Fix subpage scrub repair failure
>>>>>    Caused by hardcoded PAGE_SIZE
>>>>>
>>>>> - Fix free space cache inode size
>>>>>    Same cause as scrub repair failure
>>>>>
>>>>> v3:
>>>>> - Rebased to remove write path prepration patches
>>>>>
>>>>> - Properly enable btrfs defrag
>>>>>    Previsouly, btrfs defrag is in fact just disabled.
>>>>>    This makes tons of tests in btrfs/defrag to fail.
>>>>>
>>>>> - More bug fixes for rare race/crashes
>>>>>    * Fix relocation false alert on csum mismatch
>>>>>    * Fix relocation data corruption
>>>>>    * Fix a rare case of false ASSERT()
>>>>>      The fix already get merged into the prepration patches, thus no
>>>>>      longer in this patchset though.
>>>>>    Mostly reported by Ritesh from IBM.
>>>>>
>>>>> v4:
>>>>> - Disable subpage defrag completely
>>>>>    As full page defrag can race with fsstress in btrfs/062, causing
>>>>>    strange ordered extent bugs.
>>>>>    The full subpage defrag will be submitted as an indepdent patchset.
>>>>>
>>>>> Qu Wenruo (30):
>>>>>    btrfs: pass bytenr directly to __process_pages_contig()
>>>>>    btrfs: refactor the page status update into process_one_page()
>>>>>    btrfs: provide btrfs_page_clamp_*() helpers
>>>>>    btrfs: only require sector size alignment for
>>>>>      end_bio_extent_writepage()
>>>>>    btrfs: make btrfs_dirty_pages() to be subpage compatible
>>>>>    btrfs: make __process_pages_contig() to handle subpage
>>>>>      dirty/error/writeback status
>>>>>    btrfs: make end_bio_extent_writepage() to be subpage compatible
>>>>>    btrfs: make process_one_page() to handle subpage locking
>>>>>    btrfs: introduce helpers for subpage ordered status
>>>>>    btrfs: make page Ordered bit to be subpage compatible
>>>>>    btrfs: update locked page dirty/writeback/error bits in
>>>>>      __process_pages_contig
>>>>>    btrfs: prevent extent_clear_unlock_delalloc() to unlock page not
>>>>>      locked by __process_pages_contig()
>>>>>    btrfs: make btrfs_set_range_writeback() subpage compatible
>>>>>    btrfs: make __extent_writepage_io() only submit dirty range for
>>>>>      subpage
>>>>>    btrfs: make btrfs_truncate_block() to be subpage compatible
>>>>>    btrfs: make btrfs_page_mkwrite() to be subpage compatible
>>>>>    btrfs: reflink: make copy_inline_to_page() to be subpage compatible
>>>>>    btrfs: fix the filemap_range_has_page() call in
>>>>>      btrfs_punch_hole_lock_range()
>>>>>    btrfs: don't clear page extent mapped if we're not invalidating the
>>>>>      full page
>>>>>    btrfs: extract relocation page read and dirty part into its own
>>>>>      function
>>>>>    btrfs: make relocate_one_page() to handle subpage case
>>>>>    btrfs: fix wild subpage writeback which does not have ordered
>>>>> extent.
>>>>>    btrfs: disable inline extent creation for subpage
>>>>>    btrfs: allow submit_extent_page() to do bio split for subpage
>>>>>    btrfs: reject raid5/6 fs for subpage
>>>>>    btrfs: fix a crash caused by race between prepare_pages() and
>>>>>      btrfs_releasepage()
>>>>>    btrfs: fix a use-after-free bug in writeback subpage helper
>>>>>    btrfs: fix a subpage false alert for relocating partial 
>>>>> preallocated
>>>>>      data extents
>>>>>    btrfs: fix a subpage relocation data corruption
>>>>>    btrfs: allow read-write for 4K sectorsize on 64K page size systems
>>>>>
>>>>>   fs/btrfs/ctree.h        |   2 +-
>>>>>   fs/btrfs/disk-io.c      |  13 +-
>>>>>   fs/btrfs/extent_io.c    | 563
>>>>> ++++++++++++++++++++++++++++------------
>>>>>   fs/btrfs/file.c         |  32 ++-
>>>>>   fs/btrfs/inode.c        | 147 +++++++++--
>>>>>   fs/btrfs/ioctl.c        |   6 +
>>>>>   fs/btrfs/ordered-data.c |   5 +-
>>>>>   fs/btrfs/reflink.c      |  14 +-
>>>>>   fs/btrfs/relocation.c   | 287 ++++++++++++--------
>>>>>   fs/btrfs/subpage.c      | 156 ++++++++++-
>>>>>   fs/btrfs/subpage.h      |  31 +++
>>>>>   fs/btrfs/super.c        |   7 -
>>>>>   fs/btrfs/sysfs.c        |   5 +
>>>>>   fs/btrfs/volumes.c      |   8 +
>>>>>   14 files changed, 949 insertions(+), 327 deletions(-)
>>>>>
>>>>