[PATCH v3 0/2] btrfs: re-define btrfs_raid_types

[Qu Wenruo <wqu@suse.com>]

[CHANGELOG]
Changelog:
v2:
- Fix the start value of BTRFS_RAID_RAID0

v3:
- Introduce more static sanity checks
  They are kinda overkilled, but they are only compile time checks, it
  should be fine.

- Keep btrfs_bg_flags_to_raid_index() as regular function

By the nature of BTRFS_BLOCK_GROUP_* profiles, converting the flag into
an index should only need one bits AND, one if () check for SINGLE
profile, one right shift to align the values, one ilog2() call which is
normally converted into ffs() assembly code.

But we're using a lot of if () branches to do the convert.

This patch will re-define btrfs_raid_types by:

- Move it to volumes.h
  btrfs_raid_types are only used internally, no need to be exposed
  through UAPI.

- Re-order btrfs_raid_types
  To make them match their value order.

- Use ilog2() to convert them into index

- Extra static_assert()s to make sure RAID0 is always the least
  significant bit in PROFILE_MASK


Qu Wenruo (2):
  btrfs: move definition of btrfs_raid_types to volumes.h
  btrfs: use ilog2() to replace if () branches for
    btrfs_bg_flags_to_raid_index()

 fs/btrfs/space-info.h           |  2 ++
 fs/btrfs/volumes.c              | 24 ++++++----------------
 fs/btrfs/volumes.h              | 35 +++++++++++++++++++++++++++++++++
 include/uapi/linux/btrfs_tree.h | 13 ------------
 4 files changed, 43 insertions(+), 31 deletions(-)

-- 
2.35.1