[PATCH 1/5] block: add disk sequence number

Matteo Croce
2021-02-06T02:54:55Z

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

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 9e741a4f351b..4dbf589e1610 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1425,8 +1425,17 @@ 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,
@@ -1601,6 +1610,8 @@ 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_bdput:
@@ -2149,3 +2160,11 @@ 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 809aaa32d53c..2e5a0b8893db 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -177,6 +177,7 @@ struct gendisk {
int node_id;
struct badblocks *bb;
struct lockdep_map lockdep_map;
+ u64 diskseq;
};

/*
@@ -335,6 +336,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev,
#endif /* CONFIG_SYSFS */

extern struct rw_semaphore bdev_lookup_sem;
+extern void inc_diskseq(struct gendisk *disk);

dev_t blk_lookup_devt(const char *name, int partno);
void blk_request_module(dev_t devt);
--
2.29.2