1 files changed, 27 insertions, 13 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index a5fd5cb20a3c..46050500529b 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -121,29 +121,43 @@ struct btrfs_eb_write_context {
  *
  * Will handle both sectorsize == PAGE_SIZE and sectorsize < PAGE_SIZE cases.
  */
-static inline size_t get_eb_offset_in_page(const struct extent_buffer *eb,
-					   unsigned long offset)
+static inline size_t get_eb_offset_in_folio(const struct extent_buffer *eb,
+					    unsigned long offset)
 {
 	/*
-	 * For sectorsize == PAGE_SIZE case, eb->start will always be aligned
-	 * to PAGE_SIZE, thus adding it won't cause any difference.
+	 * 1) sectorsize == PAGE_SIZE and nodesize >= PAGE_SIZE case
+	 *    1.1) One large folio covering the whole eb
+	 *	   The eb->start is aligned to folio size, thus adding it
+	 *	   won't cause any difference.
+	 *    1.2) Several page sized folios
+	 *	   The eb->start is aligned to folio (page) size, thus
+	 *	   adding it won't cause any difference.
 	 *
-	 * For sectorsize < PAGE_SIZE, we must only read the data that belongs
-	 * to the eb, thus we have to take the eb->start into consideration.
+	 * 2) sectorsize < PAGE_SIZE and nodesize < PAGE_SIZE case
+	 *    In this case there would only be one page sized folio, and there
+	 *    may be several different extent buffers in the page/folio.
+	 *    We need to add eb->start to properly access the offset inside
+	 *    that eb.
 	 */
-	return offset_in_page(offset + eb->start);
+	return offset_in_folio(eb->folios[0], offset + eb->start);
 }
 
-static inline unsigned long get_eb_page_index(unsigned long offset)
+static inline unsigned long get_eb_folio_index(const struct extent_buffer *eb,
+					       unsigned long offset)
 {
 	/*
-	 * For sectorsize == PAGE_SIZE case, plain >> PAGE_SHIFT is enough.
+	 * 1) sectorsize == PAGE_SIZE and nodesize >= PAGE_SIZE case
+	 *    1.1) One large folio covering the whole eb.
+	 *	   the folio_shift would be large enough to always make us
+	 *	   return 0 as index.
+	 *    1.2) Several page sized folios
+	 *         The folio_shift() would be PAGE_SHIFT, giving us the correct
+	 *         index.
 	 *
-	 * For sectorsize < PAGE_SIZE case, we only support 64K PAGE_SIZE,
-	 * and have ensured that all tree blocks are contained in one page,
-	 * thus we always get index == 0.
+	 * 2) sectorsize < PAGE_SIZE and nodesize < PAGE_SIZE case
+	 *    The folio would only be page sized, and always give us 0 as index.
 	 */
-	return offset >> PAGE_SHIFT;
+	return offset >> folio_shift(eb->folios[0]);
 }
 
 /*