[0/8] btrfs: separate/simplify/unify subpage handling

Message

Qu Wenruo Jan. 29, 2025, 7:37 a.m. UTC

[METADATA SUBPAGE CHECKS]
Currently we only have one btrfs_is_subpage() check, utilized by data
and metadata.

But the truth is, btrfs_is_subpage() can return incorrect result if the
target folio belongs to a dummy extent buffer.

This means we have quite some metadata call sites doing their own
metadata specific subpage check.

[SUBPAGE SPECIFIC HANDLINGS]
There are several functions that split the metadata subpage handling
into a dedicated path.

But the truth is, a lot of such paths only have minor differences
compared to the regular routine.

[THIS SERIES]
This series address the above problems and prepare for the incoming data
larger folio support by:

- Remove btrfs_fs_info::sectors_per_page
  This is mostly a preparation for the future data larger folio support.

- Introduce a dedicated metadata specific subpage check

- Unify/simplify metadata subpage handling
  So that we have a single unified path for metadata

Qu Wenruo (8):
  btrfs: remove btrfs_fs_info::sectors_per_page
  btrfs: extract metadata subpage detection into a dedicated helper
  btrfs: make subpage attach and detach to handle metadata properly
  btrfs: use metadata specific helpers to simplify extent buffer helpers
  btrfs: simplify btrfs_clear_buffer_dirty()
  btrfs: simplify write_one_eb()
  btrfs: simplify read_extent_buffer_pages_nowait()
  btrfs: require strict data/metadata split for subpage check

 fs/btrfs/disk-io.c   |   5 +-
 fs/btrfs/extent_io.c | 193 +++++++++++++++----------------------------
 fs/btrfs/fs.h        |   7 +-
 fs/btrfs/subpage.c   | 173 ++++++++++++++++++++++----------------
 fs/btrfs/subpage.h   |  50 +++++++++--
 5 files changed, 222 insertions(+), 206 deletions(-)