btrfs: disable bs > ps support if no transparent hugepage support

Btrfs relies on mapping_set_folio_order_range() to set the minimal
folio order for all its data inodes, but that function will be no-op if
transparent hugepage is not enabled.

Guard the bs > ps support behind CONFIG_TRANSPARENT_HUGEPAGE, just like
all other filesystems.

Fixes: 98077f7f21 ("btrfs: enable experimental bs > ps support")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/Kconfig

@@ -106,7 +106,8 @@ config BTRFS_EXPERIMENTAL
 
 	  - extent tree v2 - complex rework of extent tracking
 
-	  - block size > page size support
+	  - block size > page size support - needs transparent huge page and
+					     non-HIGHMEM system
 
 	  - huge folios for data - folios can be as large as 2MiB now
 

fs/btrfs/fs.c

@@ -166,9 +166,17 @@ bool __attribute_const__ btrfs_supported_blocksize(u32 blocksize)
 	 *
 	 * Considering HIGHMEM is such a pain to deal with and it's going
 	 * to be deprecated eventually, just reject HIGHMEM && bs > ps cases.
+	 *
+	 * Finally, for bs > ps cases, we need to set the minimal folio order,
+	 * which requires transparent hugepage.
 	 */
-	if (IS_ENABLED(CONFIG_HIGHMEM) && blocksize > PAGE_SIZE)
-		return false;
+	if (blocksize > PAGE_SIZE) {
+		if (IS_ENABLED(CONFIG_HIGHMEM))
+			return false;
+
+		if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
+			return false;
+	}
 	return true;
 #endif
 	return false;