This patch introduce the following functions to handle btrfs subpage
uptodate status:
- btrfs_subpage_set_uptodate()
- btrfs_subpage_clear_uptodate()
- btrfs_subpage_test_uptodate()
  Those helpers can only be called when the range is ensured to be
  inside the page.

- btrfs_page_set_uptodate()
- btrfs_page_clear_uptodate()
- btrfs_page_test_uptodate()
  Those helpers can handle both regular sector size and subpage without
  problem.
  Although caller should still ensure that the range is inside the page.

Signed-off-by: Qu Wenruo <[email protected]>
---
 fs/btrfs/subpage.h | 84 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index c1556b3b68f3..2b2d25cc6cba 100644
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -23,6 +23,7 @@
 struct btrfs_subpage {
        /* Common members for both data and metadata pages */
        spinlock_t lock;
+       u16 uptodate_bitmap;
        union {
                /* Structures only used by metadata */
                struct {
@@ -102,4 +103,87 @@ static inline bool btrfs_subpage_clear_and_test_tree_block(
        return last;
 }
 
+static inline void btrfs_subpage_set_uptodate(struct btrfs_fs_info *fs_info,
+                       struct page *page, u64 start, u32 len)
+{
+       struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
+       u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
+       unsigned long flags;
+
+       spin_lock_irqsave(&subpage->lock, flags);
+       subpage->uptodate_bitmap |= tmp;
+       if (subpage->uptodate_bitmap == U16_MAX)
+               SetPageUptodate(page);
+       spin_unlock_irqrestore(&subpage->lock, flags);
+}
+
+static inline void btrfs_subpage_clear_uptodate(struct btrfs_fs_info *fs_info,
+                       struct page *page, u64 start, u32 len)
+{
+       struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
+       u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
+       unsigned long flags;
+
+       spin_lock_irqsave(&subpage->lock, flags);
+       subpage->uptodate_bitmap &= ~tmp;
+       ClearPageUptodate(page);
+       spin_unlock_irqrestore(&subpage->lock, flags);
+}
+
+/*
+ * Unlike set/clear which is dependent on each page status, for test all bits
+ * are tested in the same way.
+ */
+#define DECLARE_BTRFS_SUBPAGE_TEST_OP(name)                            \
+static inline bool btrfs_subpage_test_##name(struct btrfs_fs_info *fs_info, \
+                       struct page *page, u64 start, u32 len)          \
+{                                                                      \
+       struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; \
+       u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len); \
+       unsigned long flags;                                            \
+       bool ret;                                                       \
+                                                                       \
+       spin_lock_irqsave(&subpage->lock, flags);                       \
+       ret = ((subpage->name##_bitmap & tmp) == tmp);                  \
+       spin_unlock_irqrestore(&subpage->lock, flags);                  \
+       return ret;                                                     \
+}
+DECLARE_BTRFS_SUBPAGE_TEST_OP(uptodate);
+
+/*
+ * Note that, in selftest, especially extent-io-tests, we can have empty
+ * fs_info passed in.
+ * Thankfully in selftest, we only test sectorsize == PAGE_SIZE cases so far,
+ * thus we can fall back to regular sectorsize branch.
+ */
+#define DECLARE_BTRFS_PAGE_OPS(name, set_page_func, clear_page_func,   \
+                              test_page_func)                          \
+static inline void btrfs_page_set_##name(struct btrfs_fs_info *fs_info,        
\
+                       struct page *page, u64 start, u32 len)          \
+{                                                                      \
+       if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) {   \
+               set_page_func(page);                                    \
+               return;                                                 \
+       }                                                               \
+       btrfs_subpage_set_##name(fs_info, page, start, len);            \
+}                                                                      \
+static inline void btrfs_page_clear_##name(struct btrfs_fs_info *fs_info, \
+                       struct page *page, u64 start, u32 len)          \
+{                                                                      \
+       if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) {   \
+               clear_page_func(page);                                  \
+               return;                                                 \
+       }                                                               \
+       btrfs_subpage_clear_##name(fs_info, page, start, len);          \
+}                                                                      \
+static inline bool btrfs_page_test_##name(struct btrfs_fs_info *fs_info, \
+                       struct page *page, u64 start, u32 len)          \
+{                                                                      \
+       if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE)     \
+               return test_page_func(page);                            \
+       return btrfs_subpage_test_##name(fs_info, page, start, len);    \
+}
+DECLARE_BTRFS_PAGE_OPS(uptodate, SetPageUptodate, ClearPageUptodate,
+                       PageUptodate);
+
 #endif /* BTRFS_SUBPAGE_H */
-- 
2.29.2

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