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 <w...@suse.com>
---
fs/btrfs/subpage.h | 115 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 115 insertions(+)
diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index d8b34879368d..3373ef4ffec1 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 */
bool under_alloc;
@@ -78,4 +79,118 @@ static inline void btrfs_page_end_meta_alloc(struct
btrfs_fs_info *fs_info,
int btrfs_attach_subpage(struct btrfs_fs_info *fs_info, struct page *page);
void btrfs_detach_subpage(struct btrfs_fs_info *fs_info, struct page *page);
+/*
+ * Convert the [start, start + len) range into a u16 bitmap
+ *
+ * E.g. if start == page_offset() + 16K, len = 16K, we get 0x00f0.
+ */
+static inline u16 btrfs_subpage_calc_bitmap(struct btrfs_fs_info *fs_info,
+ struct page *page, u64 start, u32 len)
+{
+ int bit_start = offset_in_page(start) >> fs_info->sectorsize_bits;
+ 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. Here we make the
+ * first left shift to be calculated in unsigned long (u32), then
+ * truncate the result to u16.
+ */
+ return (u16)(((1UL << nbits) - 1) << bit_start);
+}
+
+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); \
+}
