btrfs: simplify the btree folio wait during invalidation

The btree inode is very different from regular data inodes, as the btree
inode is never exposed to user space operations.

All operations are either initiated by btrfs metadata operations, or MM
layer like memory pressure to release folios.

This means we never need to handle partial folio invalidation inside
btree_invalidate_folio().

With that said, we can slightly simplify the btree folio invalidation
by:

- Add ASSERT()s to make sure the range covers the whole folio

- Remove "if (start > end)" check
  As the range always covers the full folio, that check is always
  false and can be removed.

- Open code extent_invalidate_folio()

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2026-05-03 19:17:51 +09:30 • committed by David Sterba
commit 2b5e433488