[PATCH v2 1/5] block/genhd: Notify udev about capacity change

Balbir Singh
2020-02-25T20:01:59Z

Allow block/genhd to notify user space (via udev) about disk size changes
using a new helper set_capacity_revalidate_and_notify(), which is a wrapper
on top of set_capacity(). set_capacity_revalidate_and_notify() will only
notify via udev if the current capacity or the target capacity is not zero
and iff the capacity changes.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Someswarudu Sangaraju <ssomesh@amazon.com>
Signed-off-by: Balbir Singh <sblbir@amazon.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
---
block/genhd.c | 24 ++++++++++++++++++++++++
include/linux/genhd.h | 2 ++
2 files changed, 26 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index ff6268970ddc..6a60131baffa 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -46,6 +46,30 @@ static void disk_add_events(struct gendisk *disk);
static void disk_del_events(struct gendisk *disk);
static void disk_release_events(struct gendisk *disk);

+/*
+ * Set disk capacity and notify if the size is not currently
+ * zero and will not be set to zero
+ */
+void set_capacity_revalidate_and_notify(struct gendisk *disk, sector_t size,
+ bool revalidate)
+{
+ sector_t capacity = get_capacity(disk);
+
+ set_capacity(disk, size);
+
+ if (revalidate)
+ revalidate_disk(disk);
+
+ if (capacity != size && capacity != 0 && size != 0) {
+ char *envp[] = { "RESIZE=1", NULL };
+
+ kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
+ }
+}
+
+EXPORT_SYMBOL_GPL(set_capacity_revalidate_and_notify);
+
+
void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, int rw)
{
if (queue_is_mq(q))
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 6fbe58538ad6..f77f5095f20b 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -461,6 +461,8 @@ static inline int get_disk_ro(struct gendisk *disk)
extern void disk_block_events(struct gendisk *disk);
extern void disk_unblock_events(struct gendisk *disk);
extern void disk_flush_events(struct gendisk *disk, unsigned int mask);
+extern void set_capacity_revalidate_and_notify(struct gendisk *disk,
+ sector_t size, bool revalidate);
extern unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask);

/* drivers/char/random.c */
--
2.16.6