On Mon, 12 Jul 2021 19:22:43 +0000
"Elliott, Robert (Servers)" [off-list ref] wrote:

quoted

-----Original Message-----
From: Matteo Croce <redacted>
Sent: Sunday, July 11, 2021 12:54 PM

...

quoted

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

From: Matteo Croce <redacted>

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);
    }

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?

Hi,

what's the difference with this?

	case BLKGETSIZE64:
		return put_u64(argp, i_size_read(bdev->bd_inode));

The returned int is an error code, not the diskseq value itself, e.g.

	case BLKFRAGET:
		if (!argp)
			return -EINVAL;

Regards,
-- 
per aspera ad upstream