[PATCH v5 3/6] block: add ioctl to read the disk sequence number

From: Matteo Croce
Date: Mon Jul 12 2021 - 19:07:48 EST


From: Matteo Croce <mcroce@xxxxxxxxxxxxx>

Add a new BLKGETDISKSEQ ioctl which retrieves the disk sequence number
from the genhd structure.

# ./getdiskseq /dev/loop*
/dev/loop0: 13
/dev/loop0p1: 13
/dev/loop0p2: 13
/dev/loop0p3: 13
/dev/loop1: 14
/dev/loop1p1: 14
/dev/loop1p2: 14
/dev/loop2: 5
/dev/loop3: 6

Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxxxxx>
---
block/ioctl.c | 2 ++
include/uapi/linux/fs.h | 1 +
2 files changed, 3 insertions(+)

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 BLKZEROOUT:
return blk_ioctl_zeroout(bdev, mode, arg);
+ case BLKGETDISKSEQ:
+ return put_u64(argp, bdev->bd_disk->diskseq);
case BLKREPORTZONE:
return blkdev_report_zones_ioctl(bdev, mode, cmd, arg);
case BLKRESETZONE:
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 4c32e97dcdf0..bdf7b404b3e7 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -184,6 +184,7 @@ struct fsxattr {
#define BLKSECDISCARD _IO(0x12,125)
#define BLKROTATIONAL _IO(0x12,126)
#define BLKZEROOUT _IO(0x12,127)
+#define BLKGETDISKSEQ _IOR(0x12,128,__u64)
/*
* A jump here: 130-136 are reserved for zoned block devices
* (see uapi/linux/blkzoned.h)
--
2.31.1