* [PATCH] blkcg: Make blkg_root_lookup() work for queues in bypass mode
@ 2018-08-10 20:28 Bart Van Assche
2018-08-11 21:41 ` Jens Axboe
0 siblings, 1 reply; 2+ messages in thread
From: Bart Van Assche @ 2018-08-10 20:28 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block, Christoph Hellwig, Bart Van Assche, Tejun Heo
For legacy queues the only call of blkg_root_lookup() happens after
bypass mode has been enabled. Since blkg_lookup() returns NULL for
queues in bypass mode, modify the blkg_root_lookup() such that it
no longer depends on bypass mode. Rename the function into
blk_queue_root_blkg() as suggested by Tejun.
Suggested-by: Tejun Heo <tj@kernel.org>
Fixes: 6bad9b210a22 ("blkcg: Introduce blkg_root_lookup()")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
---
block/blk-sysfs.c | 2 +-
include/linux/blk-cgroup.h | 15 +++++----------
2 files changed, 6 insertions(+), 11 deletions(-)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index fcadea471779..1bec13c4eb88 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -813,7 +813,7 @@ static void __blk_release_queue(struct work_struct *work)
blk_exit_queue(q);
}
- WARN(blkg_root_lookup(q),
+ WARN(blk_queue_root_blkg(q),
"request queue %p is being released but it has not yet been removed from the blkcg controller\n",
q);
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 2b08616dcc11..30bbe053627c 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -344,20 +344,14 @@ static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
}
/**
- * blkg_lookup - look up blkg for the specified request queue
+ * blk_queue_root_blkg - return blkg for the (blkcg_root, @q) pair
* @q: request_queue of interest
*
* Lookup blkg for @q at the root level. See also blkg_lookup().
*/
-static inline struct blkcg_gq *blkg_root_lookup(struct request_queue *q)
+static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
{
- struct blkcg_gq *blkg;
-
- rcu_read_lock();
- blkg = blkg_lookup(&blkcg_root, q);
- rcu_read_unlock();
-
- return blkg;
+ return q->root_blkg;
}
/**
@@ -883,7 +877,8 @@ static inline bool blk_cgroup_congested(void) { return false; }
static inline void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) { }
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
-static inline struct blkcg_gq *blkg_root_lookup(struct request_queue *q) { return NULL; }
+static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
+{ return NULL; }
static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
static inline void blkcg_drain_queue(struct request_queue *q) { }
static inline void blkcg_exit_queue(struct request_queue *q) { }
--
2.18.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] blkcg: Make blkg_root_lookup() work for queues in bypass mode
2018-08-10 20:28 [PATCH] blkcg: Make blkg_root_lookup() work for queues in bypass mode Bart Van Assche
@ 2018-08-11 21:41 ` Jens Axboe
0 siblings, 0 replies; 2+ messages in thread
From: Jens Axboe @ 2018-08-11 21:41 UTC (permalink / raw)
To: Bart Van Assche; +Cc: linux-block, Christoph Hellwig, Tejun Heo
On 8/10/18 2:28 PM, Bart Van Assche wrote:
> For legacy queues the only call of blkg_root_lookup() happens after
> bypass mode has been enabled. Since blkg_lookup() returns NULL for
> queues in bypass mode, modify the blkg_root_lookup() such that it
> no longer depends on bypass mode. Rename the function into
> blk_queue_root_blkg() as suggested by Tejun.
Applied, thanks.
--
Jens Axboe
^ permalink raw reply [flat|nested] 2+ messages in thread
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