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, 5 insertions, 2 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 2b6027ebf265..4342d654a954 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -626,6 +626,7 @@ static void end_bbio_data_read(struct btrfs_bio *bbio)
  * Populate every free slot in a provided array with folios using GFP_NOFS.
  *
  * @nr_folios:   number of folios to allocate
+ * @order:	 the order of the folios to be allocated
  * @folio_array: the array to fill with folios; any existing non-NULL entries in
  *		 the array will be skipped
  *
@@ -633,12 +634,13 @@ static void end_bbio_data_read(struct btrfs_bio *bbio)
  *         -ENOMEM  otherwise, the partially allocated folios would be freed and
  *                  the array slots zeroed
  */
-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)
 {
 	for (int i = 0; i < nr_folios; i++) {
 		if (folio_array[i])
 			continue;
-		folio_array[i] = folio_alloc(GFP_NOFS, 0);
+		folio_array[i] = folio_alloc(GFP_NOFS, order);
 		if (!folio_array[i])
 			goto error;
 	}
@@ -647,6 +649,7 @@ error:
 	for (int i = 0; i < nr_folios; i++) {
 		if (folio_array[i])
 			folio_put(folio_array[i]);
+		folio_array[i] = NULL;
 	}
 	return -ENOMEM;
 }