diff options
| author | Tejun Heo <tj@kernel.org> | 2019-06-13 15:30:39 -0700 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-06-15 10:39:39 -0600 |
| commit | ef069b97feec11c2399bbc5f6f347b35482105dc (patch) | |
| tree | 72014b442cbeacfac5af39651a51f33e28fcb2b9 | |
| parent | f539da82f2158916e154d206054e0efd5df7ab61 (diff) | |
blkcg: perpcu_ref init/exit should be done from blkg_alloc/free()
blkg alloc is performed as a separate step from the rest of blkg
creation so that GFP_KERNEL allocations can be used when creating
blkgs from configuration file writes because otherwise user actions
may fail due to failures of opportunistic GFP_NOWAIT allocations.
While making blkgs use percpu_ref, 7fcf2b033b84 ("blkcg: change blkg
reference counting to use percpu_ref") incorrectly added unconditional
opportunistic percpu_ref_init() to blkg_create() breaking this
guarantee.
This patch moves percpu_ref_init() to blkg_alloc() so makes it use
@gfp_mask that blkg_alloc() is called with. Also, percpu_ref_exit()
is moved to blkg_free() for consistency.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 7fcf2b033b84 ("blkcg: change blkg reference counting to use percpu_ref")
Cc: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-cgroup.c | 13 |
1 files changed, 4 insertions, 9 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index e4715b35d42c..04d286934c5e 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -79,6 +79,7 @@ static void blkg_free(struct blkcg_gq *blkg) blkg_rwstat_exit(&blkg->stat_ios); blkg_rwstat_exit(&blkg->stat_bytes); + percpu_ref_exit(&blkg->refcnt); kfree(blkg); } @@ -86,8 +87,6 @@ static void __blkg_release(struct rcu_head *rcu) { struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head); - percpu_ref_exit(&blkg->refcnt); - /* release the blkcg and parent blkg refs this blkg has been holding */ css_put(&blkg->blkcg->css); if (blkg->parent) @@ -132,6 +131,9 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, if (!blkg) return NULL; + if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) + goto err_free; + if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) || blkg_rwstat_init(&blkg->stat_ios, gfp_mask)) goto err_free; @@ -244,11 +246,6 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, blkg_get(blkg->parent); } - ret = percpu_ref_init(&blkg->refcnt, blkg_release, 0, - GFP_NOWAIT | __GFP_NOWARN); - if (ret) - goto err_cancel_ref; - /* invoke per-policy init */ for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkcg_policy *pol = blkcg_policy[i]; @@ -281,8 +278,6 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, blkg_put(blkg); return ERR_PTR(ret); -err_cancel_ref: - percpu_ref_exit(&blkg->refcnt); err_put_congested: wb_congested_put(wb_congested); err_put_css: |