btrfs: use metadata specific helpers to simplify extent buffer helpers

The following functions are doing metadata specific checks:

- set_extent_buffer_uptodate()
- clear_extent_buffer_uptodate()

The reason why we do not use btrfs_folio_*() helpers for those helpers
is, btrfs_is_subpage() cannot handle dummy extent buffer if nodesize >=
PAGE_SIZE but block size < PAGE_SIZE.

In that case, we do not need to attach extra bitmaps to the extent
buffer folio. But since dummy extent buffer folios are not attached to
btree inode, btrfs_is_subpage() will return true, causing problems.

And the following are using btrfs_folio_*() helpers for metadata, but
in theory we should use metadata specific checks:

- set_extent_buffer_dirty()

This is not causing problems because a dummy extent buffer should never
be marked dirty.

To make code simpler, introduce btrfs_meta_folio_*() helpers, to do
the metadata specific handling, so that we do not to open-code such
checks in above involved functions.

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

fs/btrfs/extent_io.c

@@ -3442,8 +3442,8 @@ void set_extent_buffer_dirty(struct extent_buffer *eb)
 		if (subpage)
 			folio_lock(eb->folios[0]);
 		for (int i = 0; i < num_folios; i++)
-			btrfs_folio_set_dirty(eb->fs_info, eb->folios[i],
-					      eb->start, eb->len);
+			btrfs_meta_folio_set_dirty(eb->fs_info, eb->folios[i],
+						   eb->start, eb->len);
 		if (subpage)
 			folio_unlock(eb->folios[0]);
 		percpu_counter_add_batch(&eb->fs_info->dirty_metadata_bytes,
@@ -3468,15 +3468,7 @@ void clear_extent_buffer_uptodate(struct extent_buffer *eb)
 		if (!folio)
 			continue;
 
-		/*
-		 * This is special handling for metadata subpage, as regular
-		 * btrfs_is_subpage() can not handle cloned/dummy metadata.
-		 */
-		if (!btrfs_meta_is_subpage(fs_info))
-			folio_clear_uptodate(folio);
-		else
-			btrfs_subpage_clear_uptodate(fs_info, folio,
-						     eb->start, eb->len);
+		btrfs_meta_folio_clear_uptodate(fs_info, folio, eb->start, eb->len);
 	}
 }
 
@@ -3489,15 +3481,7 @@ void set_extent_buffer_uptodate(struct extent_buffer *eb)
 	for (int i = 0; i < num_folios; i++) {
 		struct folio *folio = eb->folios[i];
 
-		/*
-		 * This is special handling for metadata subpage, as regular
-		 * btrfs_is_subpage() can not handle cloned/dummy metadata.
-		 */
-		if (!btrfs_meta_is_subpage(fs_info))
-			folio_mark_uptodate(folio);
-		else
-			btrfs_subpage_set_uptodate(fs_info, folio,
-						   eb->start, eb->len);
+		btrfs_meta_folio_set_uptodate(fs_info, folio, eb->start, eb->len);
 	}
 }
 

fs/btrfs/subpage.c

@@ -651,6 +651,31 @@ bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info,	\
 		return folio_test_func(folio);				\
 	btrfs_subpage_clamp_range(folio, &start, &len);			\
 	return btrfs_subpage_test_##name(fs_info, folio, start, len);	\
+}									\
+void btrfs_meta_folio_set_##name(const struct btrfs_fs_info *fs_info,   \
+				 struct folio *folio, u64 start, u32 len) \
+{									\
+	if (!btrfs_meta_is_subpage(fs_info)) {				\
+		folio_set_func(folio);					\
+		return;							\
+	}								\
+	btrfs_subpage_set_##name(fs_info, folio, start, len);		\
+}									\
+void btrfs_meta_folio_clear_##name(const struct btrfs_fs_info *fs_info, \
+				   struct folio *folio, u64 start, u32 len) \
+{									\
+	if (!btrfs_meta_is_subpage(fs_info)) {				\
+		folio_clear_func(folio);				\
+		return;							\
+	}								\
+	btrfs_subpage_clear_##name(fs_info, folio, start, len);		\
+}									\
+bool btrfs_meta_folio_test_##name(const struct btrfs_fs_info *fs_info,	\
+				  struct folio *folio, u64 start, u32 len) \
+{									\
+	if (!btrfs_meta_is_subpage(fs_info))				\
+		return folio_test_func(folio);				\
+	return btrfs_subpage_test_##name(fs_info, folio, start, len);	\
 }
 IMPLEMENT_BTRFS_PAGE_OPS(uptodate, folio_mark_uptodate, folio_clear_uptodate,
 			 folio_test_uptodate);

fs/btrfs/subpage.h

@@ -128,6 +128,13 @@ void btrfs_folio_end_lock_bitmap(const struct btrfs_fs_info *fs_info,
  * btrfs_folio_clamp_*() are similar to btrfs_folio_*(), except the range doesn't
  * need to be inside the page. Those functions will truncate the range
  * automatically.
+ *
+ * Both btrfs_folio_*() and btrfs_folio_clamp_*() are for data folios.
+ *
+ * For metadata, one should use btrfs_meta_folio_*() helpers instead, and there
+ * is no clamp version for metadata helpers, as we either go subpage
+ * (nodesize < PAGE_SIZE) or go regular folio helpers (nodesize >= PAGE_SIZE,
+ * and our folio is never larger than nodesize).
  */
 #define DECLARE_BTRFS_SUBPAGE_OPS(name)					\
 void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info,	\
@@ -147,7 +154,13 @@ void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info,	\
 void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info,	\
 		struct folio *folio, u64 start, u32 len);			\
 bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info,	\
-		struct folio *folio, u64 start, u32 len);
+		struct folio *folio, u64 start, u32 len);		\
+void btrfs_meta_folio_set_##name(const struct btrfs_fs_info *fs_info,	\
+		struct folio *folio, u64 start, u32 len);		\
+void btrfs_meta_folio_clear_##name(const struct btrfs_fs_info *fs_info,	\
+		struct folio *folio, u64 start, u32 len);		\
+bool btrfs_meta_folio_test_##name(const struct btrfs_fs_info *fs_info,	\
+		struct folio *folio, u64 start, u32 len);		\
 
 DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
 DECLARE_BTRFS_SUBPAGE_OPS(dirty);