On Thu, Jul 25, 2019 at 11:33:49AM +0200, Johannes Thumshirn wrote:
> Create a structure to encode the type and length for the known on-disk
> checksums. Also add a table and a convenience macro for adding the
> checksum types to the table.
>
> This makes it easier to add new checksums later.
>
> Signed-off-by: Johannes Thumshirn <jthumsh...@suse.de>
> ---
> fs/btrfs/ctree.h | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index da97ff10f421..099401f5dd47 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -82,9 +82,15 @@ struct btrfs_ref;
> */
> #define BTRFS_LINK_MAX 65535U
>
> -/* four bytes for CRC32 */
> -static const int btrfs_csum_sizes[] = { 4 };
> -static const char *btrfs_csum_names[] = { "crc32c" };
> +#define BTRFS_CHECKSUM_TYPE(_type, _size, _name) \
> + [_type] = { .size = _size, .name = _name }
I think the macro initializer might be an overkill here, there are only
3 items to initialize.
> +
> +static const struct btrfs_csums {
> + u16 size;
> + const char *name;
> +} btrfs_csums[] = {
> + BTRFS_CHECKSUM_TYPE(BTRFS_CSUM_TYPE_CRC32, 4, "crc32c"),
> +};
>
> #define BTRFS_EMPTY_DIR_SIZE 0
>
> @@ -2373,13 +2379,13 @@ static inline int btrfs_super_csum_size(const struct
> btrfs_super_block *s)
> /*
> * csum type is validated at mount time
> */
> - return btrfs_csum_sizes[t];
> + return btrfs_csums[t].size;
> }
>
> static inline const char *btrfs_super_csum_name(u16 csum_type)
> {
> /* csum type is validated at mount time */
> - return btrfs_csum_names[csum_type];
> + return btrfs_csums[csum_type].name;
> }
This has been in the code already, but shouldn't the btrfs_csums table
be declared in ctree.h and defined in eg. in ctree.c? As ctree.h is
included by everything we have multiple copies of it in the .o files.
