btrfs: subpage: introduce helpers for dirty status

Introduce the following functions to handle subpage dirty status:

- btrfs_subpage_set_dirty()
- btrfs_subpage_clear_dirty()
- btrfs_subpage_test_dirty()
  These helpers can only be called when the range is ensured to be
  inside the page.

- btrfs_page_set_dirty()
- btrfs_page_clear_dirty()
- btrfs_page_test_dirty()
  These helpers can handle both regular sector size and subpage without
  problem.
  Thus they would be used to replace PageDirty() related calls in
  later patches.

There is one special point to note here, just like set_page_dirty() and
clear_page_dirty_for_io(), btrfs_*page_set_dirty() and
btrfs_*page_clear_dirty() must be called with page locked.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index b86a4881475d..f47fa08f2415 100644
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -20,6 +20,7 @@ struct btrfs_subpage {
 	spinlock_t lock;
 	u16 uptodate_bitmap;
 	u16 error_bitmap;
+	u16 dirty_bitmap;
 	union {
 		/*
 		 * Structures only used by metadata
@@ -87,5 +88,9 @@ bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info,	\
 
 DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
 DECLARE_BTRFS_SUBPAGE_OPS(error);
+DECLARE_BTRFS_SUBPAGE_OPS(dirty);
+
+bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
+		struct page *page, u64 start, u32 len);
 
 #endif