diff options
| author | Christoph Hellwig <hch@lst.de> | 2017-08-23 19:10:30 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2017-08-23 12:49:52 -0600 |
| commit | 807d4af2f64ed79fdbb28e582e330be3dbe10d23 (patch) | |
| tree | 11ed994bb09f7739c8d746f8d39b82df07aa7740 | |
| parent | de65b0123216a8e1dbe3ca1eb20a45572b9e71d9 (diff) | |
block: add a __disk_get_part helper
This helper allows looking up a partion under RCU protection without
grabbing a reference to it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk.h | 2 | ||||
| -rw-r--r-- | 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; |