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author | Tejun Heo <tj@kernel.org> | 2012-03-05 13:15:09 -0800 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2012-03-06 21:27:22 +0100 |
commit | 7a4dd281ec66224f802093962d1d903d86b09560 (patch) | |
tree | c38c5c40464d4d7eb429cc14348a435176832ef2 /block/blk-throttle.c | |
parent | 4bfd482e73b30284cb21e10834ce729fa81aa256 (diff) | |
download | linux-7a4dd281ec66224f802093962d1d903d86b09560.tar.gz linux-7a4dd281ec66224f802093962d1d903d86b09560.tar.bz2 linux-7a4dd281ec66224f802093962d1d903d86b09560.zip |
blkcg: kill the mind-bending blkg->dev
blkg->dev is dev_t recording the device number of the block device for
the associated request_queue. It is used to identify the associated
block device when printing out configuration or stats.
This is redundant to begin with. A blkg is an association between a
cgroup and a request_queue and it of course is possible to reach
request_queue from blkg and synchronization conventions are in place
for safe q dereferencing, so this shouldn't be necessary from the
beginning. Furthermore, it's initialized by sscanf()ing the device
name of backing_dev_info. The mind boggles.
Anyways, if blkg is visible under rcu lock, we *know* that the
associated request_queue hasn't gone away yet and its bdi is
registered and alive - blkg can't be created for request_queue which
hasn't been fully initialized and it can't go away before blkg is
removed.
Let stat and conf read functions get device name from
blkg->q->backing_dev_info.dev and pass it down to printing functions
and remove blkg->dev.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-throttle.c')
-rw-r--r-- | block/blk-throttle.c | 51 |
1 files changed, 2 insertions, 49 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 791b10719e43..52a429397d3b 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -212,50 +212,12 @@ static struct blkio_group *throtl_alloc_blkio_group(struct request_queue *q, return &tg->blkg; } -static void -__throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg) -{ - struct backing_dev_info *bdi = &td->queue->backing_dev_info; - unsigned int major, minor; - - if (!tg || tg->blkg.dev) - return; - - /* - * Fill in device details for a group which might not have been - * filled at group creation time as queue was being instantiated - * and driver had not attached a device yet - */ - if (bdi->dev && dev_name(bdi->dev)) { - sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); - tg->blkg.dev = MKDEV(major, minor); - } -} - -/* - * Should be called with without queue lock held. Here queue lock will be - * taken rarely. It will be taken only once during life time of a group - * if need be - */ -static void -throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg) -{ - if (!tg || tg->blkg.dev) - return; - - spin_lock_irq(td->queue->queue_lock); - __throtl_tg_fill_dev_details(td, tg); - spin_unlock_irq(td->queue->queue_lock); -} - static void throtl_link_blkio_group(struct request_queue *q, struct blkio_group *blkg) { struct throtl_data *td = q->td; struct throtl_grp *tg = tg_of_blkg(blkg); - __throtl_tg_fill_dev_details(td, tg); - hlist_add_head(&tg->tg_node, &td->tg_list); td->nr_undestroyed_grps++; } @@ -263,20 +225,14 @@ static void throtl_link_blkio_group(struct request_queue *q, static struct throtl_grp *throtl_lookup_tg(struct throtl_data *td, struct blkio_cgroup *blkcg) { - struct throtl_grp *tg = NULL; - /* * This is the common case when there are no blkio cgroups. * Avoid lookup in this case */ if (blkcg == &blkio_root_cgroup) - tg = td->root_tg; - else - tg = tg_of_blkg(blkg_lookup(blkcg, td->queue, - BLKIO_POLICY_THROTL)); + return td->root_tg; - __throtl_tg_fill_dev_details(td, tg); - return tg; + return tg_of_blkg(blkg_lookup(blkcg, td->queue, BLKIO_POLICY_THROTL)); } static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td, @@ -303,7 +259,6 @@ static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td, tg = td->root_tg; } - __throtl_tg_fill_dev_details(td, tg); return tg; } @@ -1090,8 +1045,6 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) blkcg = task_blkio_cgroup(current); tg = throtl_lookup_tg(td, blkcg); if (tg) { - throtl_tg_fill_dev_details(td, tg); - if (tg_no_rule_group(tg, rw)) { blkiocg_update_dispatch_stats(&tg->blkg, bio->bi_size, rw, rw_is_sync(bio->bi_rw)); |