[PATCH v4 09/18] btrfs: introduce helper for subpage error status

[Qu Wenruo]

This patch introduce the following functions to handle btrfs subpage
error status:
- btrfs_subpage_set_error()
- btrfs_subpage_clear_error()
- btrfs_subpage_test_error()
  Those helpers can only be called when the range is ensured to be
  inside the page.

- btrfs_page_set_error()
- btrfs_page_clear_error()
- btrfs_page_test_error()
  Those helpers can handle both regular sector size and subpage without
  problem.

Signed-off-by: Qu Wenruo <w...@suse.com>
---
 fs/btrfs/subpage.h | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index 3373ef4ffec1..5da5441c08cb 100644
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -24,6 +24,7 @@ struct btrfs_subpage {
        /* Common members for both data and metadata pages */
        spinlock_t lock;
        u16 uptodate_bitmap;
+       u16 error_bitmap;
        union {
                /* Structures only used by metadata */
                bool under_alloc;
@@ -137,6 +138,35 @@ static inline void btrfs_subpage_clear_uptodate(struct 
btrfs_fs_info *fs_info,
        spin_unlock_irqrestore(&subpage->lock, flags);
 }
 
+static inline void btrfs_subpage_set_error(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->error_bitmap |= tmp;
+       SetPageError(page);
+       spin_unlock_irqrestore(&subpage->lock, flags);
+}
+
+static inline void btrfs_subpage_clear_error(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->error_bitmap &= ~tmp;
+       if (subpage->error_bitmap == 0)
+               ClearPageError(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.
@@ -156,6 +186,7 @@ static inline bool btrfs_subpage_test_##name(struct 
btrfs_fs_info *fs_info, \
        return ret;                                                     \
 }
 DECLARE_BTRFS_SUBPAGE_TEST_OP(uptodate);
+DECLARE_BTRFS_SUBPAGE_TEST_OP(error);
 
 /*
  * Note that, in selftest, especially extent-io-tests, we can have empty
@@ -192,5 +223,6 @@ static inline bool btrfs_page_test_##name(struct 
btrfs_fs_info *fs_info, \
 }
 DECLARE_BTRFS_PAGE_OPS(uptodate, SetPageUptodate, ClearPageUptodate,
                        PageUptodate);
+DECLARE_BTRFS_PAGE_OPS(error, SetPageError, ClearPageError, PageError);
 
 #endif /* BTRFS_SUBPAGE_H */
-- 
2.30.0