[PATCH v2 0/2] btrfs: paramater refactors for data and metadata endio call backs

[Qu Wenruo <wqu@suse.com>]

This is another cleanup exposed when I'm fixing my subpage patchset.

Dating back to the old time where we still have hooks for data/metadata
endio, we have a parameter called @phy_offset for both hooks.

That @phy_offset is the number of sectors compared to the bio on-disk
bytenr, and is used to grab the csum from btrfs_io_bio.

This is far from straightforward, and costs reader tons of time to grasp
the basic.

This patchset will change it by:
- Remove phy_offset completely for metadata
  Since metadata doesn't use btrfs_io_bio::csums[] at all, there is no
  need for it.

- Use @disk_bytenr to replace @phy_offset/@icsum
  Let the callee, check_data_csum() to calculate the offset from
  @disk_bytenr and bio to get the csum offset.

Changelog:
v2:
- Update commit message to remove the wrong comment on
  btrfs_io_bio->logical
  That logical is mess, it has different meanings for different use
  cases.
  What we should refer to is bio->bi_iter.bi_sector.

- Remove the false-alert prone ASSERT()
  Even at endio time. bio->bi_iter.bi_size can change due to incoming
  finished IOs.
  This means we can't really rely on bio->bi_iter.bi_size to check if
  our disk_bytenr is still valid.

Qu Wenruo (2):
  btrfs: remove the phy_offset parameter for
    btrfs_validate_metadata_buffer()
  btrfs: pass disk_bytenr directly for check_data_csum()

 fs/btrfs/disk-io.c   |  2 +-
 fs/btrfs/disk-io.h   |  2 +-
 fs/btrfs/extent_io.c | 16 +++++++++-------
 fs/btrfs/inode.c     | 26 +++++++++++++++++---------
 4 files changed, 28 insertions(+), 18 deletions(-)

-- 
2.29.2