btrfs: make read verification handle bs > ps cases without large folios

btrfs: make read verification handle bs > ps cases without large folios

The current read verification is also relying on large folios to support
bs > ps cases, but that introduced quite some limits.

To enhance read-repair to support bs > ps without large folios:

- Make btrfs_data_csum_ok() to accept an array of paddrs
  Which can pass the paddrs[] direct into
  btrfs_calculate_block_csum_pages().

- Make repair_one_sector() to accept an array of paddrs
  So that it can submit a repair bio backed by regular pages, not only
  large folios.
  This requires us to allocate more slots at bio allocation time though.

  Also since the caller may have only partially advanced the saved_iter
  for bs > ps cases, we can not directly trust the logical bytenr from
  saved_iter (can be unaligned), thus a manual round down is necessary
  for the logical bytenr.

- Make btrfs_check_read_bio() to build an array of paddrs
  The tricky part is that we can only call btrfs_data_csum_ok() after
  all involved pages are assembled.

  This means at the call time of btrfs_check_read_bio(), our offset
  inside the bio is already at the end of the fs block.
  Thus we must re-calculate @bio_offset for btrfs_data_csum_ok() and
  repair_one_sector().

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>