[PATCH v4 2/5] block: export the diskseq in uevents

[Matteo Croce <mcroce@linux.microsoft.com>]

From: Matteo Croce <mcroce@microsoft.com>

Export the newly introduced diskseq in uevents:

    $ udevadm info /sys/class/block/* |grep -e DEVNAME -e DISKSEQ
    E: DEVNAME=/dev/loop0
    E: DISKSEQ=1
    E: DEVNAME=/dev/loop1
    E: DISKSEQ=2
    E: DEVNAME=/dev/loop2
    E: DISKSEQ=3
    E: DEVNAME=/dev/loop3
    E: DISKSEQ=4
    E: DEVNAME=/dev/loop4
    E: DISKSEQ=5
    E: DEVNAME=/dev/loop5
    E: DISKSEQ=6
    E: DEVNAME=/dev/loop6
    E: DISKSEQ=7
    E: DEVNAME=/dev/loop7
    E: DISKSEQ=8
    E: DEVNAME=/dev/nvme0n1
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p1
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p2
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p3
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p4
    E: DISKSEQ=9
    E: DEVNAME=/dev/nvme0n1p5
    E: DISKSEQ=9
    E: DEVNAME=/dev/sda
    E: DISKSEQ=10
    E: DEVNAME=/dev/sda1
    E: DISKSEQ=10
    E: DEVNAME=/dev/sda2
    E: DISKSEQ=10

Signed-off-by: Matteo Croce <mcroce@microsoft.com>
---
 block/genhd.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index b7fca2102aa3..3d9c9d189ff7 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1101,8 +1101,17 @@ static void disk_release(struct device *dev)
 		blk_put_queue(disk->queue);
 	kfree(disk);
 }
+
+static int block_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+
+	return add_uevent_var(env, "DISKSEQ=%llu", disk->diskseq);
+}
+
 struct class block_class = {
 	.name		= "block",
+	.dev_uevent	= block_uevent,
 };
 
 static char *block_devnode(struct device *dev, umode_t *mode,
-- 
2.31.1