Techwizz/kernel-fxtec-pro1x
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

block: add a __disk_get_part helper

Browse source 
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>
This commit is contained in:
Christoph Hellwig 2017-08-23 19:10:30 +02:00 • committed by Jens Axboe
parent de65b01232
commit 807d4af2f6
2 changed files with 15 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
block/blk.h
View file

@ -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); 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 #ifdef CONFIG_FAIL_IO_TIMEOUT
int blk_should_fake_timeout(struct request_queue *); int blk_should_fake_timeout(struct request_queue *);
ssize_t part_timeout_show(struct device *, struct device_attribute *, char *); ssize_t part_timeout_show(struct device *, struct device_attribute *, char *);

26
block/genhd.c
View file

@ -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_get_part - get partition
* @disk: disk to look partition from * @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 *disk_get_part(struct gendisk *disk, int partno)
{ {
struct hd_struct *part = NULL; struct hd_struct *part;
struct disk_part_tbl *ptbl;
if (unlikely(partno < 0))
return NULL;
rcu_read_lock(); rcu_read_lock();
part = __disk_get_part(disk, partno);
ptbl = rcu_dereference(disk->part_tbl); if (part)
if (likely(partno < ptbl->len)) { get_device(part_to_dev(part));
part = rcu_dereference(ptbl->part[partno]);
if (part)
get_device(part_to_dev(part));
}
rcu_read_unlock(); rcu_read_unlock();
return part; return part;