RE: [PATCH v4 3/5] block: add ioctl to read the disk sequence number

[Elliott, Robert (Servers)]

> -----Original Message-----
> From: Matteo Croce <mcroce@xxxxxxxxxxxxxxxxxxx>
> Sent: Sunday, July 11, 2021 12:54 PM
...
> Subject: [PATCH v4 3/5] block: add ioctl to read the disk sequence number
> 
> From: Matteo Croce <mcroce@xxxxxxxxxxxxx>
> 
> Add a new BLKGETDISKSEQ ioctl which retrieves the disk sequence number
> from the genhd structure.
...


Given:
    static int put_u64(u64 __user *argp, u64 val)
    {
        return put_user(val, argp);
    }

> diff --git a/block/ioctl.c b/block/ioctl.c
> index 24beec9ca9c9..0c3a4a53fa11 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -469,6 +469,8 @@ static int blkdev_common_ioctl(struct block_device
> *bdev, fmode_t mode,
>  				BLKDEV_DISCARD_SECURE);
...

> +	case BLKGETDISKSEQ:
> +		return put_u64(argp, bdev->bd_disk->diskseq);

How does that work on a system in which int is 32 bits?