| Message ID | 20181126211946.77067-3-dennis@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: always associate blkg and refcount cleanup | expand |
On Mon, Nov 26, 2018 at 04:19:35PM -0500, Dennis Zhou wrote: > To know when to create a blkg, the general pattern is to do a > blkg_lookup() and if that fails, lock and do the lookup again, and if > that fails finally create. It doesn't make much sense for everyone who > wants to do creation to write this themselves. > > This changes blkg_lookup_create() to do locking and implement this > pattern. The old blkg_lookup_create() is renamed to > __blkg_lookup_create(). If a call site wants to do its own error > handling or already owns the queue lock, they can use > __blkg_lookup_create(). This will be used in upcoming patches. > > Signed-off-by: Dennis Zhou <dennis@kernel.org> > Reviewed-by: Josef Bacik <josef@toxicpanda.com> > Acked-by: Tejun Heo <tj@kernel.org> > Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com> > --- > block/blk-cgroup.c | 30 +++++++++++++++++++++++++++--- > block/blk-iolatency.c | 2 +- > include/linux/blk-cgroup.h | 4 +++- > 3 files changed, 31 insertions(+), 5 deletions(-) > > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c > index 63d226a084cd..b1ec98eeeae0 100644 > --- a/block/blk-cgroup.c > +++ b/block/blk-cgroup.c > @@ -249,7 +249,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, > } > > /** > - * blkg_lookup_create - lookup blkg, try to create one if not there > + * __blkg_lookup_create - lookup blkg, try to create one if not there > * @blkcg: blkcg of interest > * @q: request_queue of interest > * > @@ -262,8 +262,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, > * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not > * dead and bypassing, returns ERR_PTR(-EBUSY). > */ > -struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, > - struct request_queue *q) > +struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, > + struct request_queue *q) > { > struct blkcg_gq *blkg; > > @@ -293,6 +293,30 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, > } > } > > +/** > + * blkg_lookup_create - find or create a blkg > + * @blkcg: target block cgroup > + * @q: target request_queue > + * > + * This looks up or creates the blkg representing the unique pair > + * of the blkcg and the request_queue. > + */ > +struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, > + struct request_queue *q) > +{ > + struct blkcg_gq *blkg = blkg_lookup(blkcg, q); > + > + if (unlikely(!blkg)) { > + spin_lock_irq(&q->queue_lock); > + > + blkg = __blkg_lookup_create(blkcg, q); > + > + spin_unlock_irq(&q->queue_lock); No extra spaces here please, otherwise you can add Reviewed-by: Josef Bacik <josef@toxicpanda.com> Thanks, Josef
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 63d226a084cd..b1ec98eeeae0 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -249,7 +249,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, } /** - * blkg_lookup_create - lookup blkg, try to create one if not there + * __blkg_lookup_create - lookup blkg, try to create one if not there * @blkcg: blkcg of interest * @q: request_queue of interest * @@ -262,8 +262,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not * dead and bypassing, returns ERR_PTR(-EBUSY). */ -struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, - struct request_queue *q) +struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) { struct blkcg_gq *blkg; @@ -293,6 +293,30 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, } } +/** + * blkg_lookup_create - find or create a blkg + * @blkcg: target block cgroup + * @q: target request_queue + * + * This looks up or creates the blkg representing the unique pair + * of the blkcg and the request_queue. + */ +struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q) +{ + struct blkcg_gq *blkg = blkg_lookup(blkcg, q); + + if (unlikely(!blkg)) { + spin_lock_irq(&q->queue_lock); + + blkg = __blkg_lookup_create(blkcg, q); + + spin_unlock_irq(&q->queue_lock); + } + + return blkg; +} + static void blkg_destroy(struct blkcg_gq *blkg) { struct blkcg *blkcg = blkg->blkcg; diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index fe0c4ca312ff..e6f68f15dee9 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -486,7 +486,7 @@ static void blkcg_iolatency_throttle(struct rq_qos *rqos, struct bio *bio) blkg = blkg_lookup(blkcg, q); if (unlikely(!blkg)) { spin_lock_irq(&q->queue_lock); - blkg = blkg_lookup_create(blkcg, q); + blkg = __blkg_lookup_create(blkcg, q); if (IS_ERR(blkg)) blkg = NULL; spin_unlock_irq(&q->queue_lock); diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index db8214047486..49f399cfb0b6 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -181,6 +181,8 @@ extern struct cgroup_subsys_state * const blkcg_root_css; struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, struct request_queue *q, bool update_hint); +struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, + struct request_queue *q); struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, struct request_queue *q); int blkcg_init_queue(struct request_queue *q); @@ -799,7 +801,7 @@ static inline bool blkcg_bio_issue_check(struct request_queue *q, blkg = blkg_lookup(blkcg, q); if (unlikely(!blkg)) { spin_lock_irq(&q->queue_lock); - blkg = blkg_lookup_create(blkcg, q); + blkg = __blkg_lookup_create(blkcg, q); if (IS_ERR(blkg)) blkg = NULL; spin_unlock_irq(&q->queue_lock);