This helper allows looking up a partion under RCU protection without grabbing a reference to it.
Signed-off-by: Christoph Hellwig <[email protected]> --- block/blk.h | 2 ++ block/genhd.c | 26 +++++++++++++------------- 2 files changed, 15 insertions(+), 13 deletions(-) diff --git a/block/blk.h b/block/blk.h index 3a3d715bd725..fde8b351c166 100644 --- a/block/blk.h +++ b/block/blk.h @@ -204,6 +204,8 @@ static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq e->type->ops.sq.elevator_deactivate_req_fn(q, rq); } +struct hd_struct *__disk_get_part(struct gendisk *disk, int partno); + #ifdef CONFIG_FAIL_IO_TIMEOUT int blk_should_fake_timeout(struct request_queue *); ssize_t part_timeout_show(struct device *, struct device_attribute *, char *); diff --git a/block/genhd.c b/block/genhd.c index 3380a1e73ea0..713b7d4fe7a1 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -82,6 +82,15 @@ void part_in_flight(struct request_queue *q, struct hd_struct *part, } } +struct hd_struct *__disk_get_part(struct gendisk *disk, int partno) +{ + struct disk_part_tbl *ptbl = rcu_dereference(disk->part_tbl); + + if (unlikely(partno < 0 || partno >= ptbl->len)) + return NULL; + return rcu_dereference(ptbl->part[partno]); +} + /** * disk_get_part - get partition * @disk: disk to look partition from @@ -98,21 +107,12 @@ void part_in_flight(struct request_queue *q, struct hd_struct *part, */ struct hd_struct *disk_get_part(struct gendisk *disk, int partno) { - struct hd_struct *part = NULL; - struct disk_part_tbl *ptbl; - - if (unlikely(partno < 0)) - return NULL; + struct hd_struct *part; rcu_read_lock(); - - ptbl = rcu_dereference(disk->part_tbl); - if (likely(partno < ptbl->len)) { - part = rcu_dereference(ptbl->part[partno]); - if (part) - get_device(part_to_dev(part)); - } - + part = __disk_get_part(disk, partno); + if (part) + get_device(part_to_dev(part)); rcu_read_unlock(); return part; -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
