btrfs: introduce helpers for subpage ordered status

This patch introduces the following functions to handle btrfs subpage
ordered (Private2) status:

- btrfs_subpage_set_ordered()
- btrfs_subpage_clear_ordered()
- btrfs_subpage_test_ordered()
  These helpers can only be called when the range is ensured to be
  inside the page.

- btrfs_page_set_ordered()
- btrfs_page_clear_ordered()
- btrfs_page_test_ordered()
  These helpers can handle both regular sector size and subpage without
  problem.

These functions are here to coordinate btrfs_invalidatepage() with
btrfs_writepage_endio_finish_ordered(), to make sure only one of those
functions can finish the ordered extent.

Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index 9d087ab3244e..65298a5efe7b 100644
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -34,6 +34,9 @@ struct btrfs_subpage {
 		struct {
 			atomic_t readers;
 			atomic_t writers;
+
+			/* Tracke pending ordered extent in this sector */
+			u16 ordered_bitmap;
 		};
 	};
 };
@@ -111,6 +114,7 @@ DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
 DECLARE_BTRFS_SUBPAGE_OPS(error);
 DECLARE_BTRFS_SUBPAGE_OPS(dirty);
 DECLARE_BTRFS_SUBPAGE_OPS(writeback);
+DECLARE_BTRFS_SUBPAGE_OPS(ordered);
 
 bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
 		struct page *page, u64 start, u32 len);