Guard all the code to punt bios to a per-cgroup submission helper by a
new CONFIG_BLK_CGROUP_PUNT_BIO symbol that is selected by btrfs.
This way non-btrfs kernel builds don't need to have this code.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/Kconfig | 3 ++
block/blk-cgroup.c | 77 +++++++++++++++++++++++++---------------------
block/blk-cgroup.h | 3 +-
fs/btrfs/Kconfig | 1 +
4 files changed, 48 insertions(+), 36 deletions(-)
diff --git a/block/Kconfig b/block/Kconfig
index 941b2dca70db73..69ccf7457ae110 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -41,6 +41,9 @@ config BLK_RQ_ALLOC_TIME
config BLK_CGROUP_RWSTAT
bool
+config BLK_CGROUP_PUNT_BIO
+ bool
+
config BLK_DEV_BSG_COMMON
tristate
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index c524ecab440b8f..18c922579719b5 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -56,7 +56,6 @@ static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
bool blkcg_debug_stats = false;
-static struct workqueue_struct *blkcg_punt_bio_wq;
#define BLKG_DESTROY_BATCH_SIZE 64
@@ -166,7 +165,9 @@ static void __blkg_release(struct rcu_head *rcu)
{
struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head);
+#ifdef CONFIG_BLK_CGROUP_PUNT_BIO
WARN_ON(!bio_list_empty(&blkg->async_bios));
+#endif
/* release the blkcg and parent blkg refs this blkg has been holding */
css_put(&blkg->blkcg->css);
@@ -188,6 +189,9 @@ static void blkg_release(struct percpu_ref *ref)
call_rcu(&blkg->rcu_head, __blkg_release);
}
+#ifdef CONFIG_BLK_CGROUP_PUNT_BIO
+static struct workqueue_struct *blkcg_punt_bio_wq;
+
static void blkg_async_bio_workfn(struct work_struct *work)
{
struct blkcg_gq *blkg = container_of(work, struct blkcg_gq,
@@ -214,6 +218,40 @@ static void blkg_async_bio_workfn(struct work_struct *work)
blk_finish_plug(&plug);
}
+/*
+ * When a shared kthread issues a bio for a cgroup, doing so synchronously can
+ * lead to priority inversions as the kthread can be trapped waiting for that
+ * cgroup. Use this helper instead of submit_bio to punt the actual issuing to
+ * a dedicated per-blkcg work item to avoid such priority inversions.
+ */
+void blkcg_punt_bio_submit(struct bio *bio)
+{
+ struct blkcg_gq *blkg = bio->bi_blkg;
+
+ if (blkg->parent) {
+ spin_lock(&blkg->async_bio_lock);
+ bio_list_add(&blkg->async_bios, bio);
+ spin_unlock(&blkg->async_bio_lock);
+ queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work);
+ } else {
+ /* never bounce for the root cgroup */
+ submit_bio(bio);
+ }
+}
+EXPORT_SYMBOL_GPL(blkcg_punt_bio_submit);
+
+static int __init blkcg_punt_bio_init(void)
+{
+ blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio",
+ WQ_MEM_RECLAIM | WQ_FREEZABLE |
+ WQ_UNBOUND | WQ_SYSFS, 0);
+ if (!blkcg_punt_bio_wq)
+ return -ENOMEM;
+ return 0;
+}
+subsys_initcall(blkcg_punt_bio_init);
+#endif /* CONFIG_BLK_CGROUP_PUNT_BIO */
+
/**
* bio_blkcg_css - return the blkcg CSS associated with a bio
* @bio: target bio
@@ -269,10 +307,12 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk,
blkg->q = disk->queue;
INIT_LIST_HEAD(&blkg->q_node);
+ blkg->blkcg = blkcg;
+#ifdef CONFIG_BLK_CGROUP_PUNT_BIO
spin_lock_init(&blkg->async_bio_lock);
bio_list_init(&blkg->async_bios);
INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn);
- blkg->blkcg = blkcg;
+#endif
u64_stats_init(&blkg->iostat.sync);
for_each_possible_cpu(cpu) {
@@ -1688,28 +1728,6 @@ void blkcg_policy_unregister(struct blkcg_policy *pol)
}
EXPORT_SYMBOL_GPL(blkcg_policy_unregister);
-/*
- * When a shared kthread issues a bio for a cgroup, doing so synchronously can
- * lead to priority inversions as the kthread can be trapped waiting for that
- * cgroup. Use this helper instead of submit_bio to punt the actual issuing to
- * a dedicated per-blkcg work item to avoid such priority inversions.
- */
-void blkcg_punt_bio_submit(struct bio *bio)
-{
- struct blkcg_gq *blkg = bio->bi_blkg;
-
- if (blkg->parent) {
- spin_lock(&blkg->async_bio_lock);
- bio_list_add(&blkg->async_bios, bio);
- spin_unlock(&blkg->async_bio_lock);
- queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work);
- } else {
- /* never bounce for the root cgroup */
- submit_bio(bio);
- }
-}
-EXPORT_SYMBOL_GPL(blkcg_punt_bio_submit);
-
/*
* Scale the accumulated delay based on how long it has been since we updated
* the delay. We only call this when we are adding delay, in case it's been a
@@ -2088,16 +2106,5 @@ bool blk_cgroup_congested(void)
return ret;
}
-static int __init blkcg_init(void)
-{
- blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio",
- WQ_MEM_RECLAIM | WQ_FREEZABLE |
- WQ_UNBOUND | WQ_SYSFS, 0);
- if (!blkcg_punt_bio_wq)
- return -ENOMEM;
- return 0;
-}
-subsys_initcall(blkcg_init);
-
module_param(blkcg_debug_stats, bool, 0644);
MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not");
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 64758ab9f1f134..e98d2c1be35415 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -72,9 +72,10 @@ struct blkcg_gq {
struct blkg_iostat_set iostat;
struct blkg_policy_data *pd[BLKCG_MAX_POLS];
-
+#ifdef CONFIG_BLK_CGROUP_PUNT_BIO
spinlock_t async_bio_lock;
struct bio_list async_bios;
+#endif
union {
struct work_struct async_bio_work;
struct work_struct free_work;
diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 37b6bab90c835e..66fa9ab2c04629 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -2,6 +2,7 @@
config BTRFS_FS
tristate "Btrfs filesystem support"
+ select BLK_CGROUP_PUNT_BIO
select CRYPTO
select CRYPTO_CRC32C
select LIBCRC32C
--
2.39.2
