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Subject[PATCH 12/12] blkcg: rename blkg_try_get to blkg_tryget
Date
From: "Dennis Zhou (Facebook)" <dennisszhou@gmail.com>

blkg reference counting now uses percpu_ref rather than atomic_t. Let's
make this consistent with css_tryget. This renames blkg_try_get to
blkg_tryget and now returns a bool rather than the blkg or NULL.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
block/bio.c | 2 +-
block/blk-cgroup.c | 3 +--
block/blk-iolatency.c | 2 +-
include/linux/blk-cgroup.h | 14 ++++++--------
4 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index a65ab3bacb4f..14351fac07cd 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1975,7 +1975,7 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
{
if (unlikely(bio->bi_blkg))
return -EBUSY;
- bio->bi_blkg = blkg_try_get_closest(blkg);
+ bio->bi_blkg = blkg_tryget_closest(blkg);
return 0;
}

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index ab3676e1e15e..76136bea7a7f 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1794,8 +1794,7 @@ void blkcg_maybe_throttle_current(void)
blkg = blkg_lookup(blkcg, q);
if (!blkg)
goto out;
- blkg = blkg_try_get(blkg);
- if (!blkg)
+ if (!blkg_tryget(blkg))
goto out;
rcu_read_unlock();

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 9d7052bad6f7..5a4cec54c998 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -628,7 +628,7 @@ static void blkiolatency_timer_fn(struct timer_list *t)
* We could be exiting, don't access the pd unless we have a
* ref on the blkg.
*/
- if (!blkg_try_get(blkg))
+ if (!blkg_tryget(blkg))
continue;

iolat = blkg_to_lat(blkg);
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 7ff5d8ba8c7a..b7fd08013de2 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -494,27 +494,25 @@ static inline void blkg_get(struct blkcg_gq *blkg)
}

/**
- * blkg_try_get - try and get a blkg reference
+ * blkg_tryget - try and get a blkg reference
* @blkg: blkg to get
*
* This is for use when doing an RCU lookup of the blkg. We may be in the midst
* of freeing this blkg, so we can only use it if the refcnt is not zero.
*/
-static inline struct blkcg_gq *blkg_try_get(struct blkcg_gq *blkg)
+static inline bool blkg_tryget(struct blkcg_gq *blkg)
{
- if (percpu_ref_tryget(&blkg->refcnt))
- return blkg;
- return NULL;
+ return percpu_ref_tryget(&blkg->refcnt);
}

/**
- * blkg_try_get_closest - try and get a blkg ref on the closet blkg
+ * blkg_tryget_closest - try and get a blkg ref on the closet blkg
* @blkg: blkg to get
*
* This walks up the blkg tree to find the closest non-dying blkg and returns
* the blkg that it did association with as it may not be the passed in blkg.
*/
-static inline struct blkcg_gq *blkg_try_get_closest(struct blkcg_gq *blkg)
+static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
{
while (!percpu_ref_tryget(&blkg->refcnt))
blkg = blkg->parent;
@@ -599,7 +597,7 @@ static inline struct request_list *blk_get_rl(struct request_queue *q,
if (unlikely(!blkg))
blkg = __blkg_lookup_create(blkcg, q);

- if (!blkg_try_get(blkg))
+ if (!blkg_tryget(blkg))
goto rl_use_root;

rcu_read_unlock();
--
2.17.1
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