btrfs: prepare compression folio alloc/free for bs > ps cases

This includes the following preparation for bs > ps cases:

- Always alloc/free the folio directly if bs > ps
  This adds a new @fs_info parameter for btrfs_alloc_compr_folio(), thus
  affecting all compression algorithms.

  For btrfs_free_compr_folio() it needs no parameter for now, as we can
  use the folio size to skip the caching part.

  For now the change is just to passing a @fs_info into the function,
  all the folio size assumption is still based on page size.

- Properly zero the last folio in compress_file_range()
  Since the compressed folios can be larger than a page, we need to
  properly zero the whole folio.

- Use correct folio size for btrfs_add_compressed_bio_folios()
  Instead of page size, use the correct folio size.

- Use correct folio size/shift for btrfs_compress_filemap_get_folio()
  As we are not only using simple page sized folios anymore.

- Use correct folio size for btrfs_decompress()
  There is an ASSERT() making sure the decompressed range is no larger
  than a page, which will be triggered for bs > ps cases.

- Skip readahead for compressed pages
  Similar to subpage cases.

- Make btrfs_alloc_folio_array() to accept a new @order parameter

- Add a helper to calculate the minimal folio size

All those changes should not affect the existing bs <= ps handling.

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

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 61130786b9a3..5fcbfe44218c 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -366,7 +366,8 @@ void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans,
 
 int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array,
 			   bool nofail);
-int btrfs_alloc_folio_array(unsigned int nr_folios, struct folio **folio_array);
+int btrfs_alloc_folio_array(unsigned int nr_folios, unsigned int order,
+			    struct folio **folio_array);
 
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
 bool find_lock_delalloc_range(struct inode *inode,