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

On Mon, Jul 12, 2021 at 07:22:43PM +0000, Elliott, Robert (Servers) wrote:

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

quoted

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);

...

quoted

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

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

Why would it not work?  put_user is a magic macro that works on all
scalar value.