@@ -101,3 +101,117 @@ void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
ASSERT(atomic_read(&subpage->eb_refs));
atomic_dec(&subpage->eb_refs);
}
+
+/*
+ * Convert the [start, start + len) range into a u16 bitmap
+ *
+ * For example: if start == page_offset() + 16K, len = 16K, we get 0x00f0.
+ */
+static inline u16 btrfs_subpage_calc_bitmap(
+ const struct btrfs_fs_info *fs_info, struct page *page,
+ u64 start, u32 len)
+{
+ const int bit_start = offset_in_page(start) >> fs_info->sectorsize_bits;
+ const int nbits = len >> fs_info->sectorsize_bits;
+
+ /* Basic checks */
+ ASSERT(PagePrivate(page) && page->private);
+ ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
+ IS_ALIGNED(len, fs_info->sectorsize));
+
+ /*
+ * The range check only works for mapped page, we can still have
+ * unampped page like dummy extent buffer pages.
+ */
+ if (page->mapping)
+ ASSERT(page_offset(page) <= start &&
+ start + len <= page_offset(page) + PAGE_SIZE);
+ /*
+ * Here nbits can be 16, thus can go beyond u16 range. We make the
+ * first left shift to be calculate in unsigned long (at least u32),
+ * then truncate the result to u16.
+ */
+ return (u16)(((1UL << nbits) - 1) << bit_start);
+}
+
+void btrfs_subpage_set_uptodate(const struct btrfs_fs_info *fs_info,
+ struct page *page, u64 start, u32 len)
+{
+ struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
+ const 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);
+}
+
+void btrfs_subpage_clear_uptodate(const struct btrfs_fs_info *fs_info,
+ struct page *page, u64 start, u32 len)
+{
+ struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
+ const 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 IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(name) \
+bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
+ struct page *page, u64 start, u32 len) \
+{ \
+ struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; \
+ const 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; \
+}
+IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(uptodate);
+
+/*
+ * Note that, in selftests (extent-io-tests), we can have empty fs_info passed
+ * in. We only test sectorsize == PAGE_SIZE cases so far, thus we can fall
+ * back to regular sectorsize branch.
+ */
+#define IMPLEMENT_BTRFS_PAGE_OPS(name, set_page_func, clear_page_func, \
+ test_page_func) \
+void btrfs_page_set_##name(const 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); \
+} \
+void btrfs_page_clear_##name(const 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); \
+} \
+bool btrfs_page_test_##name(const 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); \
+}
+IMPLEMENT_BTRFS_PAGE_OPS(uptodate, SetPageUptodate, ClearPageUptodate,
+ PageUptodate);
@@ -19,6 +19,7 @@
struct btrfs_subpage {
/* Common members for both data and metadata pages */
spinlock_t lock;
+ u16 uptodate_bitmap;
union {
/*
* Structures only used by metadata
@@ -51,4 +52,31 @@ void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,
struct page *page);
void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
struct page *page);
+
+/*
+ * Template for subpage related operations.
+ *
+ * btrfs_subpage_*() are for call sites where the page has subpage attached and
+ * the range is ensured to be inside the page.
+ *
+ * btrfs_page_*() are for call sites where the page can either be subpage
+ * specific or regular page. The function will handle both cases.
+ * But the range still needs to be inside the page.
+ */
+#define DECLARE_BTRFS_SUBPAGE_OPS(name) \
+void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
+ struct page *page, u64 start, u32 len); \
+void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
+ struct page *page, u64 start, u32 len); \
+bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
+ struct page *page, u64 start, u32 len); \
+void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \
+ struct page *page, u64 start, u32 len); \
+void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \
+ struct page *page, u64 start, u32 len); \
+bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \
+ struct page *page, u64 start, u32 len);
+
+DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
+
#endif