[PATCH 0/2] btrfs: remove COW fixup and checked folio flag

[Qu Wenruo <wqu@suse.com>]

For experimental builds we're already rejecting dirty folios which
don't have ordered flags since v6.15.

Unfortunately we're not yet removing that COW fixup machanism for
non-experimental builds even at v7.0, as there are still some error
corner cases that can lead to dirty folios without ordered flags.

After those years of testing, we're sure we won't need COW fixup for
regular cases. Although I want to remove the COW fixup mechanism after
all known reproducible cases are fixed, I run out of ideas.

Furthermore for the future of huge folios (order 9, 2M page on 4K page
size systems), we can not afford the extra bitmap for a huge folio.
In that case, a huge folio will need 64 bytes per bitmap, which is no
longer a small amount.

I believe it's time to remove the COW fixup mechanism even for
non-experimental builds, along with the checked folio flags.

Qu Wenruo (2):
  btrfs: remove the COW fixup mechanism
  btrfs: remove folio checked subpage bitmap tracking

 fs/btrfs/defrag.c           |   1 -
 fs/btrfs/file.c             |  10 --
 fs/btrfs/free-space-cache.c |   4 -
 fs/btrfs/inode.c            | 204 +++---------------------------------
 fs/btrfs/reflink.c          |   1 -
 fs/btrfs/subpage.c          |  39 +------
 fs/btrfs/subpage.h          |   5 +-
 7 files changed, 17 insertions(+), 247 deletions(-)

-- 
2.53.0