btrfs: constify input buffer of btrfs_csum_data

The function does not modify the input buffer, also update a typecast in
one caller.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a53ff3b..67d663a 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -265,7 +265,7 @@ out:
        return em;
 }
 
-u32 btrfs_csum_data(char *data, u32 seed, size_t len)
+u32 btrfs_csum_data(const char *data, u32 seed, size_t len)
 {
        return btrfs_crc32c(seed, data, len);
 }
@@ -3448,7 +3448,7 @@ static int write_dev_supers(struct btrfs_device *device,
                        btrfs_set_super_bytenr(sb, bytenr);
 
                        crc = ~(u32)0;
-                       crc = btrfs_csum_data((char *)sb +
+                       crc = btrfs_csum_data((const char *)sb +
                                              BTRFS_CSUM_SIZE, crc,
                                              BTRFS_SUPER_INFO_SIZE -
                                              BTRFS_CSUM_SIZE);

diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 0be2d4f..2e0ec29 100644 (file)
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -116,7 +116,7 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,
                          int atomic);
 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid);
-u32 btrfs_csum_data(char *data, u32 seed, size_t len);
+u32 btrfs_csum_data(const char *data, u32 seed, size_t len);
 void btrfs_csum_final(u32 crc, u8 *result);
 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
                        enum btrfs_wq_endio_type metadata);