block: don't hold part0's refcount in IO path (27eb3af9) · Commits · 戴 / test

block/blk.h

+6 −7

Original line number	Diff line number	Diff line
		@@ -378,18 +378,17 @@ int bdev_resize_partition(struct block_device *bdev, int partno,
		int disk_expand_part_tbl(struct gendisk *disk, int target);
		int hd_ref_init(struct hd_struct *part);

		static inline void hd_struct_get(struct hd_struct *part)
		{
		percpu_ref_get(&part->ref);
		}

		/* no need to get/put refcount of part0 */
		static inline int hd_struct_try_get(struct hd_struct *part)
		{
		if (part->partno)
		return percpu_ref_tryget_live(&part->ref);
		return 1;
		}

		static inline void hd_struct_put(struct hd_struct *part)
		{
		if (part->partno)
		percpu_ref_put(&part->ref);
		}

+2 −2

Original line number	Diff line number	Diff line
		@@ -345,7 +345,8 @@ static inline int sector_in_part(struct hd_struct *part, sector_t sector)
		*
		* CONTEXT:
		* RCU read locked. The returned partition pointer is always valid
		* because its refcount is grabbed.
		* because its refcount is grabbed except for part0, which lifetime
		* is same with the disk.
		*
		* RETURNS:
		* Found partition on success, part0 is returned if no partition matches
		@@ -378,7 +379,6 @@ struct hd_struct disk_map_sector_rcu(struct gendisk disk, sector_t sector)
		return part;
		}
		}
		hd_struct_get(&disk->part0);
		return &disk->part0;
		}