Re: [PATCH v2 1/4] UBI: update ubi-user.h and ubi-media.h

[Boris Brezillon <boris.brezillon@bootlin.com>]

On Thu, 28 Jun 2018 09:43:41 +0200
Quentin Schulz <quentin.schulz@bootlin.com> wrote:

> Update both header files to add support for flag specifying whether to
> skip the CRC check for static UBI volumes.
> 
> Taken from the kernel headers.
> 
> Some users of static UBI volumes implement their own integrity check,
> thus making the volume CRC check done at open time useless. For
> instance, this is the case when one use the ubiblock + dm-verity +
> squashfs combination, where dm-verity already checks integrity of the
> block device but this time at the block granularity instead of verifying
> the whole volume.
> 
> Skipping this test drastically improves the boot-time.
> 
> Suggested-by: Boris Brezillon <boris.brezillon@bootlin.com>
> Signed-off-by: Quentin Schulz <quentin.schulz@bootlin.com>

Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>

> ---
>  include/mtd/ubi-media.h |  6 ++++++
>  include/mtd/ubi-user.h  | 16 ++++++++++++++--
>  2 files changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/include/mtd/ubi-media.h b/include/mtd/ubi-media.h
> index 08bec3e..132cc24 100644
> --- a/include/mtd/ubi-media.h
> +++ b/include/mtd/ubi-media.h
> @@ -61,6 +61,11 @@ enum {
>   * Volume flags used in the volume table record.
>   *
>   * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
> + * @UBI_VTBL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at
> + *				 open time. Should only be set on volumes that
> + *				 are used by upper layers doing this kind of
> + *				 check. Main use-case for this flag is
> + *				 boot-time reduction
>   *
>   * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
>   * table. UBI automatically re-sizes the volume which has this flag and makes
> @@ -92,6 +97,7 @@ enum {
>   */
>  enum {
>  	UBI_VTBL_AUTORESIZE_FLG = 0x01,
> +	UBI_VTBL_SKIP_CRC_CHECK_FLG = 0x02,
>  };
>  
>  /*
> diff --git a/include/mtd/ubi-user.h b/include/mtd/ubi-user.h
> index 2b50dad..707c4f2 100644
> --- a/include/mtd/ubi-user.h
> +++ b/include/mtd/ubi-user.h
> @@ -279,6 +279,18 @@ struct ubi_attach_req {
>  	int8_t  padding[10];
>  };
>  
> +/*
> + * UBI volume flags.
> + *
> + * @UBI_VOL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at
> + *				open time. Only valid for static volumes and
> + *				should only be used if the volume user has a
> + *				way to verify data integrity
> + */
> +enum {
> +	UBI_VOL_SKIP_CRC_CHECK_FLG = 0x1,
> +};
> +
>  /**
>   * struct ubi_mkvol_req - volume description data structure used in
>   *                        volume creation requests.
> @@ -286,7 +298,7 @@ struct ubi_attach_req {
>   * @alignment: volume alignment
>   * @bytes: volume size in bytes
>   * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
> - * @padding1: reserved for future, not used, has to be zeroed
> + * @flags: volume flags (%UBI_VOL_SKIP_CRC_CHECK_FLG)
>   * @name_len: volume name length
>   * @padding2: reserved for future, not used, has to be zeroed
>   * @name: volume name
> @@ -315,7 +327,7 @@ struct ubi_mkvol_req {
>  	int32_t alignment;
>  	int64_t bytes;
>  	int8_t vol_type;
> -	int8_t padding1;
> +	uint8_t flags;
>  	int16_t name_len;
>  	int8_t padding2[4];
>  	char name[UBI_MAX_VOLUME_NAME + 1];