[PATCH 0/3] btrfs: separate BLOCK_GROUP_TREE feature from extent-tree-v2

[Qu Wenruo <wqu@suse.com>]

This is the kernel part to revive block-group-tree feature.

Thanfully unlike btrfs-progs, the changes to kernel is much smaller, and
we can re-use most of the infrastructures from the extent-tree-v2
preparation patches.

But there are still some changes needed:

- Enhance unsupporter compat RO flags handling
  Extent tree is only needed for read-write opeartions, and for
  unsupported compat RO flags, we should not do any write into the fs.

  So this patch will make the kernel to skip block group items search
  if there is any unsupport RO compat flags.

  And really make the incoming block-group-tree feature compat RO.

  Unfortunately, we need that patch to be backported, or older kernels
  will still reject RO mounts of fses with block-group-tree feature.

- Don't store block group root into super block
  There is no special reason for block group root to be stored in super
  block.
  We should review those preparation patches with more scrutiny.


For the proper time reduction introduced by this patchset, the old data
should still be correct, as the on-disk format is not changed.
https://lwn.net/Articles/801990/

Qu Wenruo (3):
  btrfs: enhance unsupported compat RO flags handling
  btrfs: don't save block group root into super block
  btrfs: separate BLOCK_GROUP_TREE compat RO flag from EXTENT_TREE_V2

 fs/btrfs/block-group.c     | 11 ++++++++++-
 fs/btrfs/block-rsv.c       |  1 +
 fs/btrfs/ctree.h           | 30 ++++------------------------
 fs/btrfs/disk-io.c         | 40 +++++++++++++++++++-------------------
 fs/btrfs/disk-io.h         |  2 +-
 fs/btrfs/super.c           |  9 +++++++++
 fs/btrfs/sysfs.c           |  2 ++
 fs/btrfs/transaction.c     |  8 --------
 include/uapi/linux/btrfs.h |  6 ++++++
 9 files changed, 53 insertions(+), 56 deletions(-)

-- 
2.37.0