block: Fix dev_t minor allocation lifetime

Releases the dev_t minor when all references are closed to prevent
another device from acquiring the same major/minor.

Since the partition's release may be invoked from call_rcu's soft-irq
context, the ext_dev_idr's mutex had to be replaced with a spinlock so
as not so sleep.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/block/partition-generic.c b/block/partition-generic.c
index 789cdea05893..0d9e5f97f0a8 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -211,6 +211,7 @@ static const struct attribute_group *part_attr_groups[] = {
 static void part_release(struct device *dev)
 {
         struct hd_struct *p = dev_to_part(dev);
+        blk_free_devt(dev->devt);
         free_part_stats(p);
         free_part_info(p);
         kfree(p);
@@ -253,7 +254,6 @@ void delete_partition(struct gendisk *disk, int partno)
         rcu_assign_pointer(ptbl->last_lookup, NULL);
         kobject_put(part->holder_dir);
         device_del(part_to_dev(part));
-        blk_free_devt(part_devt(part));
 
         hd_struct_put(part);
 }