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From: Matteo Croce <mcroce@linux.microsoft.com>
To: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org,
	"Lennart Poettering" <lennart@poettering.net>,
	"Luca Boccassi" <bluca@debian.org>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Damien Le Moal" <damien.lemoal@wdc.com>,
	"Tejun Heo" <tj@kernel.org>,
	"Javier González" <javier@javigon.com>,
	"Niklas Cassel" <niklas.cassel@wdc.com>,
	"Johannes Thumshirn" <johannes.thumshirn@wdc.com>,
	"Hannes Reinecke" <hare@suse.de>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Christoph Hellwig" <hch@infradead.org>,
	JeffleXu <jefflexu@linux.alibaba.com>
Subject: [PATCH v3 1/6] block: add disk sequence number
Date: Wed, 23 Jun 2021 12:58:53 +0200	[thread overview]
Message-ID: <20210623105858.6978-2-mcroce@linux.microsoft.com> (raw)
In-Reply-To: <20210623105858.6978-1-mcroce@linux.microsoft.com>

From: Matteo Croce <mcroce@microsoft.com>

Add a monotonically increasing number to disk devices. This number is put
in the uevent so userspace can correlate events when a driver reuses a
device, like cdrom or loop.

    $ 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         | 19 +++++++++++++++++++
 include/linux/genhd.h |  2 ++
 2 files changed, 21 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 9f8cb7beaad1..c96b667136ee 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1129,8 +1129,17 @@ 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,
@@ -1304,6 +1313,8 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
 	disk_to_dev(disk)->class = &block_class;
 	disk_to_dev(disk)->type = &disk_type;
 	device_initialize(disk_to_dev(disk));
+	inc_diskseq(disk);
+
 	return disk;
 
 out_destroy_part_tbl:
@@ -1854,3 +1865,11 @@ static void disk_release_events(struct gendisk *disk)
 	WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
 	kfree(disk->ev);
 }
+
+void inc_diskseq(struct gendisk *disk)
+{
+	static atomic64_t diskseq;
+
+	disk->diskseq = atomic64_inc_return(&diskseq);
+}
+EXPORT_SYMBOL_GPL(inc_diskseq);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 6fc26f7bdf71..a0d04250a2db 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -167,6 +167,7 @@ struct gendisk {
 	int node_id;
 	struct badblocks *bb;
 	struct lockdep_map lockdep_map;
+	u64 diskseq;
 };
 
 /*
@@ -306,6 +307,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev,
 }
 #endif /* CONFIG_SYSFS */
 
+void inc_diskseq(struct gendisk *disk);
 dev_t blk_lookup_devt(const char *name, int partno);
 void blk_request_module(dev_t devt);
 #ifdef CONFIG_BLOCK
-- 
2.31.1


  reply	other threads:[~2021-06-23 10:59 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-23 10:58 [PATCH v3 0/6] block: add a sequence number to disks Matteo Croce
2021-06-23 10:58 ` Matteo Croce [this message]
2021-06-23 11:48   ` [PATCH v3 1/6] block: add disk sequence number Christoph Hellwig
2021-06-23 13:10     ` Matteo Croce
2021-06-23 13:51       ` Lennart Poettering
2021-06-23 14:01         ` Hannes Reinecke
2021-06-23 14:07           ` Luca Boccassi
2021-06-23 14:21             ` Hannes Reinecke
2021-06-23 14:34               ` Luca Boccassi
2021-06-23 14:55               ` Lennart Poettering
2021-06-23 14:12           ` Lennart Poettering
2021-06-23 15:02             ` Hannes Reinecke
2021-06-23 15:34               ` Luca Boccassi
2021-06-23 15:48               ` Lennart Poettering
2021-06-23 14:28       ` Christoph Hellwig
2021-06-23 10:58 ` [PATCH v3 2/6] block: add ioctl to read the " Matteo Croce
2021-06-23 10:58 ` [PATCH v3 3/6] block: refactor sysfs code Matteo Croce
2021-06-23 11:52   ` Christoph Hellwig
2021-06-23 19:03     ` Matteo Croce
2021-06-24  6:12       ` Christoph Hellwig
2021-06-23 10:58 ` [PATCH v3 4/6] block: export diskseq in sysfs Matteo Croce
2021-06-23 10:58 ` [PATCH v3 5/6] block: increment sequence number Matteo Croce
2021-06-23 10:58 ` [PATCH v3 6/6] loop: " Matteo Croce
2021-06-23 11:57   ` Christoph Hellwig
2021-06-23 13:13     ` Luca Boccassi
2021-06-23 14:25       ` Christoph Hellwig
2021-06-23 15:29         ` Lennart Poettering
2021-06-24  6:11           ` Christoph Hellwig
2021-06-23 12:03 ` [PATCH v3 0/6] block: add a sequence number to disks Hannes Reinecke
2021-06-23 12:46   ` Luca Boccassi
2021-06-23 14:07   ` Lennart Poettering

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