[PATCH 0/2] btrfs: cleanup related to the 1MiB reserved space

[Qu Wenruo <wqu@suse.com>]

The 1MiB reserved space is only introduced in v4.1 btrfs-progs, and
kernel has the same reserved space around the same time.

But there are two small nitpicks:

- Kernel never has a unified MACRO for this
  We just use SZ_1M, with extra comments on this.

  This makes later write-intent bitmap harder to implement, as the
  incoming write-intent bitmap will enlarge the reserved space to
  2MiB, and use the extra 1MiB for write-intent bitmap.
  (of course with extra RO compat flags)

  This will be addressed in the first patch, with a new
  BTRFS_DEFAULT_RESERVED macro.

  Later write-intent bitmap code will use BTRFS_DEFAULT_RESERVED as a
  beacon to ensure btrfs never touches the enlarged reserved space.

- No warning on such very old fses.
  Although kernel can handle such old fses without any problem,
  it's still better to output a warning, with a solution (just balance).

  For now, we only need a warning, but for the incoming write-intent
  bitmap, any dev extents inside the extra reserved space will be
  rejected.


Qu Wenruo (2):
  btrfs: introduce BTRFS_DEFAULT_RESERVED macro
  btrfs: warn about dev extents that are inside the reserved range

 fs/btrfs/ctree.h       |  7 +++++++
 fs/btrfs/extent-tree.c |  6 +++---
 fs/btrfs/super.c       | 10 +++++-----
 fs/btrfs/volumes.c     | 17 +++++++++++------
 4 files changed, 26 insertions(+), 14 deletions(-)

-- 
2.36.1