Re: [PATCH mdadm v3 5/7] mdadm: Add --write-zeros option for Create

[Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>]

Hi Logan,
One comment from my side.

Thanks,
Mariusz

On Wed, 21 Sep 2022 14:43:54 -0600
Logan Gunthorpe <logang@deltatee.com> wrote:

> Add the --write-zeros option for Create which will send a write zeros
> request to all the disks before assembling the array. After zeroing
> the array, the disks will be in a known clean state and the initial
> sync may be skipped.
> 
> Writing zeroes is best used when there is a hardware offload method
> to zero the data. But even still, zeroing can take several minutes on
> a large device. Because of this, all disks are zeroed in parallel using
> their own forked process and a message is printed to the user. The main
> process will proceed only after all the zeroing processes have completed
> successfully.
> 
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> 
> fixup! mdadm: Add --write-zeros option for Create
> ---

> diff --git a/mdadm.h b/mdadm.h
> index 1ab31564efef..c7e00195d8c8 100644
> --- a/mdadm.h
> +++ b/mdadm.h
> @@ -273,6 +273,9 @@ static inline void __put_unaligned32(__u32 val, void *p)
>  
>  #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
>  
> +#define KIB_TO_BYTES(x)	((x) << 10)
> +#define SEC_TO_BYTES(x)	((x) << 9)
> +
>  extern const char Name[];
>  
>  struct md_bb_entry {
> @@ -387,6 +390,8 @@ struct mdinfo {
>  		ARRAY_UNKNOWN_STATE,
>  	} array_state;
>  	struct md_bb bb;
> +
> +	pid_t zero_pid;
>  };

mdinfo is  used  for raid properties. It is used for both system (sysfs_read())
and metadata(getinfo_super()). zero_pid property doesn't fit well there, it is
used once during creation. Could you please add it to mddev_dev struct or add
it to local array /list?