Re: [RFC PATCH 2/4] btrfs: create structure to encode checksum type and length

[Johannes Thumshirn <jthumshirn@suse.de>]

On Mon, Aug 12, 2019 at 12:07:44PM +0300, Nikolay Borisov wrote:
> 
> 
> On 25.07.19 г. 12:33 ч., 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 <jthumshirn@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 }
> > +
> > +static const struct btrfs_csums {
> > +	u16		size;
> > +	const char	*name;
> > +} btrfs_csums[] = {
> > +	BTRFS_CHECKSUM_TYPE(BTRFS_CSUM_TYPE_CRC32, 4, "crc32c"),
> > +};
> 
> 
> Considering we won't support more than 4-5 csums  I'd rather you remove
> the macro.

Yeah already dropped it, though I thought it might help a bit on the
readability/self-describing side.

-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
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