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authorMing Lei <ming.lei@redhat.com>2020-05-08 11:17:58 +0300
committerJens Axboe <axboe@kernel.dk>2020-05-13 05:31:40 +0300
commit27eb3af9a37a85ca35f82830a8fc29753700058a (patch)
tree5f0cc279819eb461e5ef994b862c44b4186b26f8
parent520138c3b9425c615d1417687947d86821003319 (diff)
downloadlinux-27eb3af9a37a85ca35f82830a8fc29753700058a.tar.xz
block: don't hold part0's refcount in IO path
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>
-rw-r--r--block/blk.h13
-rw-r--r--block/genhd.c4
2 files changed, 8 insertions, 9 deletions
diff --git a/block/blk.h b/block/blk.h
index 73bd3b1c6938..8c3f557dd898 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -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)
diff --git a/block/genhd.c b/block/genhd.c
index 1a51a9ad1035..afdb2c3e5b22 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -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;
}