btrfs: extent-map: unify the members with btrfs_ordered_extent

[CHANGELOG]
v2:
- Rebased to the latest for-next
  There is a conflicts with extent locking, and maybe some other
  hidden conflicts for NOCOW/PREALLOC?
  As previously the patchset passes fstests auto group, but after
  the merging with other patches, it always crashes as btrfs/060.

- Fix an error in the final cleanup patch
  It's the NOCOW/PREALLOC shenanigans again, in the buffered NOCOW path,
  that we have to use the old inaccurate numbers for NOCOW/PREALLOC OEs.

- Split the final cleanup into 4 patches
  Most cleanups are very straightforward, but the cleanup for
  btrfs_alloc_ordered_extent() needs extra special handling for
  NOCOW/PREALLOC.

v1:
- Rebased to the latest for-next
  To resolve the conflicts with the recently introduced extent map
  shrinker

- A new cleanup patch to remove the recursive header inclusion

- Use a new structure to pass the file extent item related members
  around

- Add a new comment on why we're intentionally passing incorrect
  numbers for NOCOW/PREALLOC ordered extents inside
  btrfs_create_dio_extent()

[REPO]
https://github.com/adam900710/linux/tree/em_cleanup

This series introduce two new members (disk_bytenr/offset) to
extent_map, and removes three old members
(block_start/block_len/offset), finally rename one member
(orig_block_len -> disk_num_bytes).

This should save us one u64 for extent_map, although with the recent
extent map shrinker, the saving is not that useful.

But to make things safe to migrate, I introduce extra sanity checks for
extent_map, and do cross check for both old and new members.

The extra sanity checks already exposed one bug (thankfully harmless)
causing em::block_start to be incorrect.

But so far, the patchset is fine for default fstests run.

Furthermore, since we're already having too long parameter lists for
extent_map/ordered_extent/can_nocow_extent, here is a new structure,
btrfs_file_extent, a memory-access-friendly structure to represent a
btrfs_file_extent_item.

With the help of that structure, we can use that to represent a file
extent item without a super long parameter list.

The patchset would rename orig_block_len to disk_num_bytes first.
Then introduce the new member, the extra sanity checks, and introduce the
new btrfs_file_extent structure and use that to remove the older 3 members
from extent_map.

After all above works done, use btrfs_file_extent to further cleanup
can_nocow_file_extent_args()/btrfs_alloc_ordered_extent()/create_io_em()/
btrfs_create_dio_extent().

The cleanup is in fact pretty tricky, the current code base never
expects correct numbers for NOCOW/PREALLOC OEs, thus we have to keep the
old but incorrect numbers just for NOCOW/PREALLOC.

I will address the NOCOW/PREALLOC shenanigans the future, but
after the huge cleanup across multiple core structures.

Qu Wenruo (11):
  btrfs: rename extent_map::orig_block_len to disk_num_bytes
  btrfs: export the expected file extent through can_nocow_extent()
  btrfs: introduce new members for extent_map
  btrfs: introduce extra sanity checks for extent maps
  btrfs: remove extent_map::orig_start member
  btrfs: remove extent_map::block_len member
  btrfs: remove extent_map::block_start member
  btrfs: cleanup duplicated parameters related to
    can_nocow_file_extent_args
  btrfs: cleanup duplicated parameters related to
    btrfs_alloc_ordered_extent
  btrfs: cleanup duplicated parameters related to create_io_em()
  btrfs: cleanup duplicated parameters related to
    btrfs_create_dio_extent()

 fs/btrfs/btrfs_inode.h            |   4 +-
 fs/btrfs/compression.c            |   7 +-
 fs/btrfs/defrag.c                 |  14 +-
 fs/btrfs/extent_io.c              |  10 +-
 fs/btrfs/extent_map.c             | 187 ++++++++++++------
 fs/btrfs/extent_map.h             |  51 +++--
 fs/btrfs/file-item.c              |  23 +--
 fs/btrfs/file.c                   |  18 +-
 fs/btrfs/inode.c                  | 308 +++++++++++++-----------------
 fs/btrfs/ordered-data.c           |  36 +++-
 fs/btrfs/ordered-data.h           |  22 ++-
 fs/btrfs/relocation.c             |   5 +-
 fs/btrfs/tests/extent-map-tests.c | 114 ++++++-----
 fs/btrfs/tests/inode-tests.c      | 177 ++++++++---------
 fs/btrfs/tree-log.c               |  25 +--
 fs/btrfs/zoned.c                  |   4 +-
 include/trace/events/btrfs.h      |  26 +--
 17 files changed, 548 insertions(+), 483 deletions(-)

-- 
2.45.0