Re: [PATCH v2 01/17] bcache: add comments to mark member offset of struct cache_sb_disk

Hannes Reinecke
2020-07-15T06:02:59Z

On 7/15/20 7:45 AM, Coly Li wrote:
> This patch adds comments to mark each member of struct cache_sb_disk,
> it is helpful to understand the bcache superblock on-disk layout.
>
> Signed-off-by: Coly Li <colyli@suse.de>
> ---
> include/uapi/linux/bcache.h | 39 +++++++++++++++++++------------------
> 1 file changed, 20 insertions(+), 19 deletions(-)
>
> diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h
> index 9a1965c6c3d0..afbd1b56a661 100644
> --- a/include/uapi/linux/bcache.h
> +++ b/include/uapi/linux/bcache.h
> @@ -158,33 +158,33 @@ static inline struct bkey *bkey_idx(const struct bkey *k, unsigned int nr_keys)
> #define BDEV_DATA_START_DEFAULT 16 /* sectors */
>
> struct cache_sb_disk {
> - __le64 csum;
> - __le64 offset; /* sector where this sb was written */
> - __le64 version;
> +/*000*/ __le64 csum;
> +/*008*/ __le64 offset; /* sector where this sb was written */
> +/*010*/ __le64 version;
>
> - __u8 magic[16];
> +/*018*/ __u8 magic[16];
>
> - __u8 uuid[16];
> +/*028*/ __u8 uuid[16];
> union {
> - __u8 set_uuid[16];
> +/*038*/ __u8 set_uuid[16];
> __le64 set_magic;
> };
> - __u8 label[SB_LABEL_SIZE];
> +/*048*/ __u8 label[SB_LABEL_SIZE];
>
> - __le64 flags;
> - __le64 seq;
> - __le64 pad[8];
> +/*068*/ __le64 flags;
> +/*070*/ __le64 seq;
> +/*078*/ __le64 pad[8];
>
> union {
> struct {
> /* Cache devices */
> - __le64 nbuckets; /* device size */
> +/*0b8*/ __le64 nbuckets; /* device size */
>
> - __le16 block_size; /* sectors */
> - __le16 bucket_size; /* sectors */
> +/*0c0*/ __le16 block_size; /* sectors */
> +/*0c2*/ __le16 bucket_size; /* sectors */
>
> - __le16 nr_in_set;
> - __le16 nr_this_dev;
> +/*0c4*/ __le16 nr_in_set;
> +/*0c6*/ __le16 nr_this_dev;
> };
> struct {
> /* Backing devices */
> @@ -198,14 +198,15 @@ struct cache_sb_disk {
> };
> };
>
> - __le32 last_mount; /* time overflow in y2106 */
> +/*0c8*/ __le32 last_mount; /* time overflow in y2106 */
>
> - __le16 first_bucket;
> +/*0cc*/ __le16 first_bucket;
> union {
> - __le16 njournal_buckets;
> +/*0ce*/ __le16 njournal_buckets;
> __le16 keys;
> };
> - __le64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */
> +/*0d0*/ __le64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */
> +/*8d0*/
> };
>
> struct cache_sb {
>
Common practice is to place comments at the end; please don't use the
start of the line here.

Cheers,

Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
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