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]>

4 files changed, 17 insertions, 14 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);
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index a45bc11f8665..d403641889ca 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -252,9 +252,8 @@ int lzo_compress_folios(struct list_head *ws, struct address_space *mapping,
 		/* Compress at most one sector of data each time */
 		in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);
 		ASSERT(in_len);
-		data_in = kmap_local_folio(folio_in, 0);
-		ret = lzo1x_1_compress(data_in +
-				       offset_in_page(cur_in), in_len,
+		data_in = kmap_local_folio(folio_in, offset_in_folio(folio_in, cur_in));
+		ret = lzo1x_1_compress(data_in, in_len,
 				       workspace->cbuf, &out_len,
 				       workspace->mem);
 		kunmap_local(data_in);
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 11be4f2498ba..5292cd341f70 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -203,7 +203,6 @@ int zlib_compress_folios(struct list_head *ws, struct address_space *mapping,
 				workspace->strm.next_in = workspace->buf;
 				workspace->strm.avail_in = copy_length;
 			} else {
-				unsigned int pg_off;
 				unsigned int cur_len;
 
 				if (data_in) {
@@ -215,9 +214,9 @@ int zlib_compress_folios(struct list_head *ws, struct address_space *mapping,
 						start, &in_folio);
 				if (ret < 0)
 					goto out;
-				pg_off = offset_in_page(start);
-				cur_len = btrfs_calc_input_length(orig_end, start);
-				data_in = kmap_local_folio(in_folio, pg_off);
+				cur_len = btrfs_calc_input_length(in_folio, orig_end, start);
+				data_in = kmap_local_folio(in_folio,
+							   offset_in_folio(in_folio, start));
 				start += cur_len;
 				workspace->strm.next_in = data_in;
 				workspace->strm.avail_in = cur_len;
diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 3541efa765c7..75efca4da194 100644
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -426,8 +426,8 @@ int zstd_compress_folios(struct list_head *ws, struct address_space *mapping,
 	ret = btrfs_compress_filemap_get_folio(mapping, start, &in_folio);
 	if (ret < 0)
 		goto out;
-	cur_len = btrfs_calc_input_length(orig_end, start);
-	workspace->in_buf.src = kmap_local_folio(in_folio, offset_in_page(start));
+	cur_len = btrfs_calc_input_length(in_folio, orig_end, start);
+	workspace->in_buf.src = kmap_local_folio(in_folio, offset_in_folio(in_folio, start));
 	workspace->in_buf.pos = 0;
 	workspace->in_buf.size = cur_len;
 
@@ -511,9 +511,9 @@ int zstd_compress_folios(struct list_head *ws, struct address_space *mapping,
 			ret = btrfs_compress_filemap_get_folio(mapping, start, &in_folio);
 			if (ret < 0)
 				goto out;
-			cur_len = btrfs_calc_input_length(orig_end, start);
+			cur_len = btrfs_calc_input_length(in_folio, orig_end, start);
 			workspace->in_buf.src = kmap_local_folio(in_folio,
-							 offset_in_page(start));
+							 offset_in_folio(in_folio, start));
 			workspace->in_buf.pos = 0;
 			workspace->in_buf.size = cur_len;
 		}