blk-cgroup: replace bio_blkcg with bio_blkcg_css
authorChristoph Hellwig <hch@lst.de>
Wed, 20 Apr 2022 04:27:17 +0000 (06:27 +0200)
committerJens Axboe <axboe@kernel.dk>
Mon, 2 May 2022 20:06:20 +0000 (14:06 -0600)
All callers of bio_blkcg actually want the CSS, so replace it with an
interface that does return the CSS.  This now allows to move
struct blkcg_gq to block/blk-cgroup.h instead of exposing it in a
public header.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220420042723.1010598-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block/blk-cgroup.c
block/blk-cgroup.h
drivers/block/loop.c
include/linux/blk-cgroup.h
kernel/trace/blktrace.c

index bb52797..8e32cc4 100644 (file)
@@ -155,6 +155,22 @@ static void blkg_async_bio_workfn(struct work_struct *work)
                blk_finish_plug(&plug);
 }
 
+/**
+ * bio_blkcg_css - return the blkcg CSS associated with a bio
+ * @bio: target bio
+ *
+ * This returns the CSS for the blkcg associated with a bio, or %NULL if not
+ * associated. Callers are expected to either handle %NULL or know association
+ * has been done prior to calling this.
+ */
+struct cgroup_subsys_state *bio_blkcg_css(struct bio *bio)
+{
+       if (!bio || !bio->bi_blkg)
+               return NULL;
+       return &bio->bi_blkg->blkcg->css;
+}
+EXPORT_SYMBOL_GPL(bio_blkcg_css);
+
 /**
  * blkcg_parent - get the parent of a blkcg
  * @blkcg: blkcg of interest
@@ -1938,7 +1954,7 @@ void bio_associate_blkg(struct bio *bio)
        rcu_read_lock();
 
        if (bio->bi_blkg)
-               css = &bio_blkcg(bio)->css;
+               css = bio_blkcg_css(bio);
        else
                css = blkcg_css();
 
index b00fb11..03405dd 100644 (file)
@@ -25,6 +25,64 @@ struct blkg_policy_data;
 #define BLKG_STAT_CPU_BATCH    (INT_MAX / 2)
 
 #ifdef CONFIG_BLK_CGROUP
+
+enum blkg_iostat_type {
+       BLKG_IOSTAT_READ,
+       BLKG_IOSTAT_WRITE,
+       BLKG_IOSTAT_DISCARD,
+
+       BLKG_IOSTAT_NR,
+};
+
+struct blkg_iostat {
+       u64                             bytes[BLKG_IOSTAT_NR];
+       u64                             ios[BLKG_IOSTAT_NR];
+};
+
+struct blkg_iostat_set {
+       struct u64_stats_sync           sync;
+       struct blkg_iostat              cur;
+       struct blkg_iostat              last;
+};
+
+/* association between a blk cgroup and a request queue */
+struct blkcg_gq {
+       /* Pointer to the associated request_queue */
+       struct request_queue            *q;
+       struct list_head                q_node;
+       struct hlist_node               blkcg_node;
+       struct blkcg                    *blkcg;
+
+       /* all non-root blkcg_gq's are guaranteed to have access to parent */
+       struct blkcg_gq                 *parent;
+
+       /* reference count */
+       struct percpu_ref               refcnt;
+
+       /* is this blkg online? protected by both blkcg and q locks */
+       bool                            online;
+
+       struct blkg_iostat_set __percpu *iostat_cpu;
+       struct blkg_iostat_set          iostat;
+
+       struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
+
+       spinlock_t                      async_bio_lock;
+       struct bio_list                 async_bios;
+       union {
+               struct work_struct      async_bio_work;
+               struct work_struct      free_work;
+       };
+
+       atomic_t                        use_delay;
+       atomic64_t                      delay_nsec;
+       atomic64_t                      delay_start;
+       u64                             last_delay;
+       int                             last_use;
+
+       struct rcu_head                 rcu_head;
+};
+
 struct blkcg {
        struct cgroup_subsys_state      css;
        spinlock_t                      lock;
@@ -173,9 +231,9 @@ static inline struct cgroup_subsys_state *blkcg_css(void)
  *
  * In order to avoid priority inversions we sometimes need to issue a bio as if
  * it were attached to the root blkg, and then backcharge to the actual owning
- * blkg.  The idea is we do bio_blkcg() to look up the actual context for the
- * bio and attach the appropriate blkg to the bio.  Then we call this helper and
- * if it is true run with the root blkg for that queue and then do any
+ * blkg.  The idea is we do bio_blkcg_css() to look up the actual context for
+ * the bio and attach the appropriate blkg to the bio.  Then we call this helper
+ * and if it is true run with the root blkg for that queue and then do any
  * backcharging to the originating cgroup once the io is complete.
  */
 static inline bool bio_issue_as_root_blkg(struct bio *bio)
@@ -464,6 +522,9 @@ struct blkcg_policy_data {
 struct blkcg_policy {
 };
 
+struct blkcg {
+};
+
 #ifdef CONFIG_BLOCK
 
 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
index 976cf98..fabcf64 100644 (file)
@@ -1829,12 +1829,14 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
        cmd->blkcg_css = NULL;
        cmd->memcg_css = NULL;
 #ifdef CONFIG_BLK_CGROUP
-       if (rq->bio && rq->bio->bi_blkg) {
-               cmd->blkcg_css = &bio_blkcg(rq->bio)->css;
+       if (rq->bio) {
+               cmd->blkcg_css = bio_blkcg_css(rq->bio);
 #ifdef CONFIG_MEMCG
-               cmd->memcg_css =
-                       cgroup_get_e_css(cmd->blkcg_css->cgroup,
-                                       &memory_cgrp_subsys);
+               if (cmd->blkcg_css) {
+                       cmd->memcg_css =
+                               cgroup_get_e_css(cmd->blkcg_css->cgroup,
+                                               &memory_cgrp_subsys);
+               }
 #endif
        }
 #endif
index d7b1880..97c7968 100644 (file)
 #define FC_APPID_LEN              129
 
 #ifdef CONFIG_BLK_CGROUP
-
-enum blkg_iostat_type {
-       BLKG_IOSTAT_READ,
-       BLKG_IOSTAT_WRITE,
-       BLKG_IOSTAT_DISCARD,
-
-       BLKG_IOSTAT_NR,
-};
-
-struct blkg_iostat {
-       u64                             bytes[BLKG_IOSTAT_NR];
-       u64                             ios[BLKG_IOSTAT_NR];
-};
-
-struct blkg_iostat_set {
-       struct u64_stats_sync           sync;
-       struct blkg_iostat              cur;
-       struct blkg_iostat              last;
-};
-
-/* association between a blk cgroup and a request queue */
-struct blkcg_gq {
-       /* Pointer to the associated request_queue */
-       struct request_queue            *q;
-       struct list_head                q_node;
-       struct hlist_node               blkcg_node;
-       struct blkcg                    *blkcg;
-
-       /* all non-root blkcg_gq's are guaranteed to have access to parent */
-       struct blkcg_gq                 *parent;
-
-       /* reference count */
-       struct percpu_ref               refcnt;
-
-       /* is this blkg online? protected by both blkcg and q locks */
-       bool                            online;
-
-       struct blkg_iostat_set __percpu *iostat_cpu;
-       struct blkg_iostat_set          iostat;
-
-       struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
-
-       spinlock_t                      async_bio_lock;
-       struct bio_list                 async_bios;
-       union {
-               struct work_struct      async_bio_work;
-               struct work_struct      free_work;
-       };
-
-       atomic_t                        use_delay;
-       atomic64_t                      delay_nsec;
-       atomic64_t                      delay_start;
-       u64                             last_delay;
-       int                             last_use;
-
-       struct rcu_head                 rcu_head;
-};
-
 extern struct cgroup_subsys_state * const blkcg_root_css;
 
 void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay);
 void blkcg_maybe_throttle_current(void);
-
-/**
- * bio_blkcg - grab the blkcg associated with a bio
- * @bio: target bio
- *
- * This returns the blkcg associated with a bio, %NULL if not associated.
- * Callers are expected to either handle %NULL or know association has been
- * done prior to calling this.
- */
-static inline struct blkcg *bio_blkcg(struct bio *bio)
-{
-       if (bio && bio->bi_blkg)
-               return bio->bi_blkg->blkcg;
-       return NULL;
-}
-
 bool blk_cgroup_congested(void);
 void blkcg_pin_online(struct cgroup_subsys_state *blkcg_css);
 void blkcg_unpin_online(struct cgroup_subsys_state *blkcg_css);
 struct list_head *blkcg_get_cgwb_list(struct cgroup_subsys_state *css);
+struct cgroup_subsys_state *bio_blkcg_css(struct bio *bio);
 
 #else  /* CONFIG_BLK_CGROUP */
 
-struct blkcg_gq {
-};
-
 #define blkcg_root_css ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
 
 static inline void blkcg_maybe_throttle_current(void) { }
@@ -123,7 +47,10 @@ static inline bool blk_cgroup_congested(void) { return false; }
 
 #ifdef CONFIG_BLOCK
 static inline void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) { }
-static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
+static inline struct cgroup_subsys_state *bio_blkcg_css(struct bio *bio)
+{
+       return NULL;
+}
 #endif /* CONFIG_BLOCK */
 
 #endif /* CONFIG_BLK_CGROUP */
index 9ef349a..10a32b0 100644 (file)
@@ -783,6 +783,7 @@ void blk_trace_shutdown(struct request_queue *q)
 #ifdef CONFIG_BLK_CGROUP
 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
 {
+       struct cgroup_subsys_state *blkcg_css;
        struct blk_trace *bt;
 
        /* We don't use the 'bt' value here except as an optimization... */
@@ -790,9 +791,10 @@ static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)
        if (!bt || !(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
                return 0;
 
-       if (!bio->bi_blkg)
+       blkcg_css = bio_blkcg_css(bio);
+       if (!blkcg_css)
                return 0;
-       return cgroup_id(bio_blkcg(bio)->css.cgroup);
+       return cgroup_id(blkcg_css->cgroup);
 }
 #else
 static u64 blk_trace_bio_get_cgid(struct request_queue *q, struct bio *bio)