Commit 2da78092 authored by Keith Busch's avatar Keith Busch Committed by Jens Axboe
Browse files

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: default avatarKeith Busch <keith.busch@intel.com>
Cc: stable@kernel.org
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 5676e7b6

block/genhd.c

+14 −10
Original line number Diff line number Diff line
@@ -28,10 +28,10 @@ struct kobject *block_depr; 
/* for extended dynamic devt allocation, currently only one major is used */

#define NR_EXT_DEVT		(1 << MINORBITS)



/* For extended devt allocation.  ext_devt_mutex prevents look up

/* For extended devt allocation.  ext_devt_lock prevents look up

 * results from going away underneath its user.

 */

static DEFINE_MUTEX(ext_devt_mutex);

static DEFINE_SPINLOCK(ext_devt_lock);

static DEFINE_IDR(ext_devt_idr);



static struct device_type disk_type;
@@ -420,9 +420,13 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt) 
	}



	/* allocate ext devt */

	mutex_lock(&ext_devt_mutex);

	idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_KERNEL);

	mutex_unlock(&ext_devt_mutex);

	idr_preload(GFP_KERNEL);



	spin_lock(&ext_devt_lock);

	idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT);

	spin_unlock(&ext_devt_lock);



	idr_preload_end();

	if (idx < 0)

		return idx == -ENOSPC ? -EBUSY : idx;
@@ -447,9 +451,9 @@ void blk_free_devt(dev_t devt) 
		return;



	if (MAJOR(devt) == BLOCK_EXT_MAJOR) {

		mutex_lock(&ext_devt_mutex);

		spin_lock(&ext_devt_lock);

		idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));

		mutex_unlock(&ext_devt_mutex);

		spin_unlock(&ext_devt_lock);

	}

}
@@ -665,7 +669,6 @@ void del_gendisk(struct gendisk *disk) 
		sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));

	pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);

	device_del(disk_to_dev(disk));

	blk_free_devt(disk_to_dev(disk)->devt);

}

EXPORT_SYMBOL(del_gendisk);
@@ -690,13 +693,13 @@ struct gendisk *get_gendisk(dev_t devt, int *partno) 
	} else {

		struct hd_struct *part;



		mutex_lock(&ext_devt_mutex);

		spin_lock(&ext_devt_lock);

		part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));

		if (part && get_disk(part_to_disk(part))) {

			*partno = part->partno;

			disk = part_to_disk(part);

		}

		mutex_unlock(&ext_devt_mutex);

		spin_unlock(&ext_devt_lock);

	}



	return disk;
@@ -1098,6 +1101,7 @@ static void disk_release(struct device *dev) 
{

	struct gendisk *disk = dev_to_disk(dev);



	blk_free_devt(dev->devt);

	disk_release_events(disk);

	kfree(disk->random);

	disk_replace_part_tbl(disk, NULL);

block/partition-generic.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

}

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