btrfs: factor out a btrfs_csum_ptr helper

Add a helper to find the csum for a byte offset into the csum buffer.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 6e65778..613f46b 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2733,6 +2733,14 @@ int btrfs_get_extent_inline_ref_type(const struct extent_buffer *eb,
                                     enum btrfs_inline_ref_type is_data);
 u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset);
 
+static inline u8 *btrfs_csum_ptr(const struct btrfs_fs_info *fs_info, u8 *csums,
+                                u64 offset)
+{
+       u64 offset_in_sectors = offset >> fs_info->sectorsize_bits;
+
+       return csums + offset_in_sectors * fs_info->csum_size;
+}
+
 /*
  * Take the number of bytes to be checksummed and figure out how many leaves
  * it would require to store the csums for that many bytes.

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 193931b..631239f 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3371,15 +3371,12 @@ static int check_data_csum(struct inode *inode, struct btrfs_bio *bbio,
 {
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        u32 len = fs_info->sectorsize;
-       const u32 csum_size = fs_info->csum_size;
-       unsigned int offset_sectors;
        u8 *csum_expected;
        u8 csum[BTRFS_CSUM_SIZE];
 
        ASSERT(pgoff + len <= PAGE_SIZE);
 
-       offset_sectors = bio_offset >> fs_info->sectorsize_bits;
-       csum_expected = ((u8 *)bbio->csum) + offset_sectors * csum_size;
+       csum_expected = btrfs_csum_ptr(fs_info, bbio->csum, bio_offset);
 
        if (btrfs_check_sector_csum(fs_info, page, pgoff, csum, csum_expected))
                goto zeroit;
@@ -8020,12 +8017,8 @@ static inline blk_status_t btrfs_submit_dio_bio(struct bio *bio,
                if (ret)
                        goto err;
        } else {
-               u64 csum_offset;
-
-               csum_offset = file_offset - dip->file_offset;
-               csum_offset >>= fs_info->sectorsize_bits;
-               csum_offset *= fs_info->csum_size;
-               btrfs_bio(bio)->csum = dip->csums + csum_offset;
+               btrfs_bio(bio)->csum = btrfs_csum_ptr(fs_info, dip->csums,
+                                                     file_offset - dip->file_offset);
        }
 map:
        ret = btrfs_map_bio(fs_info, bio, 0);