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block: don't hold part0's refcount in IO path

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gendisk can't be gone when there is IO activity, so not hold
part0's refcount in IO path.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Cc: Yufen Yu <yuyufen@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hou Tao <houtao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2020-05-08 16:17:58 +08:00 committed by Jens Axboe
parent 520138c3b9
commit 27eb3af9a3
2 changed files with 8 additions and 9 deletions
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13
block/blk.h
View file

@ -378,19 +378,18 @@ 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)
{
return percpu_ref_tryget_live(&part->ref);
if (part->partno)
return percpu_ref_tryget_live(&part->ref);
return 1;
}
static inline void hd_struct_put(struct hd_struct *part)
{
percpu_ref_put(&part->ref);
if (part->partno)
percpu_ref_put(&part->ref);
}
static inline void hd_free_part(struct hd_struct *part)

4
block/genhd.c
View file

@ -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;
}