Currently we use u16 bitmap to make 4k sectorsize work for 64K page
size.

But this u16 bitmap is not large enough to contain larger page size like
128K, nor is space efficient for 16K page size.

To handle both cases, here we pack all subpage bitmaps into a larger
bitmap, now btrfs_subpage::bitmaps[] will be the ultimate bitmap for
subpage usage.

This is the first step towards more page size support.

Although to really enable extra page size like 16K and 128K, we need to
rework the metadata alignment check first.
Which will happen in another patchset.


Qu Wenruo (2):
  btrfs: introduce btrfs_subpage_bitmap_info
  btrfs: subpage: pack all subpage bitmaps into a larger bitmap

 fs/btrfs/ctree.h     |   1 +
 fs/btrfs/disk-io.c   |  12 ++-
 fs/btrfs/extent_io.c |  58 +++++++++------
 fs/btrfs/subpage.c   | 172 ++++++++++++++++++++++++++++++++-----------
 fs/btrfs/subpage.h   |  41 +++++++----
 5 files changed, 201 insertions(+), 83 deletions(-)

-- 
2.32.0