btrfs: prepare compression paths for large data folios

All compression algorithms inside btrfs are not supporting large folios
due to the following points:

- btrfs_calc_input_length() is assuming page sized folio

- kmap_local_folio() usages are using offset_in_page()

Prepare them to support large data folios by:

- Add a folio parameter to btrfs_calc_input_length()
  And use that folio parameter to calculate the correct length.

  Since we're here, also add extra ASSERT()s to make sure the parameter
  @cur is inside the folio range.

  This affects only zlib and zstd. Lzo compresses at most one block at a
  time, thus not affected.

- Use offset_in_folio() to calculate the kmap_local_folio() offset
  This affects all 3 algorithms.

Reviewed-by: Filipe Manana <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

1 files changed, 8 insertions, 3 deletions

diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index df198623cc08..d34c4341eaf4 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -11,7 +11,9 @@
 #include <linux/list.h>
 #include <linux/workqueue.h>
 #include <linux/wait.h>
+#include <linux/pagemap.h>
 #include "bio.h"
+#include "messages.h"
 
 struct address_space;
 struct page;
@@ -73,11 +75,14 @@ struct compressed_bio {
 };
 
 /* @range_end must be exclusive. */
-static inline u32 btrfs_calc_input_length(u64 range_end, u64 cur)
+static inline u32 btrfs_calc_input_length(struct folio *folio, u64 range_end, u64 cur)
 {
-	u64 page_end = round_down(cur, PAGE_SIZE) + PAGE_SIZE;
+	const u64 folio_end = folio_pos(folio) + folio_size(folio);
 
-	return min(range_end, page_end) - cur;
+	/* @cur must be inside the folio. */
+	ASSERT(folio_pos(folio) <= cur);
+	ASSERT(cur < folio_end);
+	return min(range_end, folio_end) - cur;
 }
 
 int __init btrfs_init_compress(void);