block/blk-cgroup.h

   1 #ifndef _BLK_CGROUP_H
   2 #define _BLK_CGROUP_H
   3 /*
   4  * Common Block IO controller cgroup interface
   5  *
   6  * Based on ideas and code from CFQ, CFS and BFQ:
   7  * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
   8  *
   9  * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
  10  *                    Paolo Valente <paolo.valente@unimore.it>
  11  *
  12  * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
  13  *                    Nauman Rafique <nauman@google.com>
  14  */
  15
  16 #include <linux/cgroup.h>
  17 #include <linux/u64_stats_sync.h>
  18 #include <linux/seq_file.h>
  19
  20 /* Max limits for throttle policy */
  21 #define THROTL_IOPS_MAX         UINT_MAX
  22
  23 /* CFQ specific, out here for blkcg->cfq_weight */
  24 #define CFQ_WEIGHT_MIN          10
  25 #define CFQ_WEIGHT_MAX          1000
  26 #define CFQ_WEIGHT_DEFAULT      500
  27
  28 #ifdef CONFIG_BLK_CGROUP
  29
  30 enum blkg_rwstat_type {
  31         BLKG_RWSTAT_READ,
  32         BLKG_RWSTAT_WRITE,
  33         BLKG_RWSTAT_SYNC,
  34         BLKG_RWSTAT_ASYNC,
  35
  36         BLKG_RWSTAT_NR,
  37         BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
  38 };
  39
  40 struct blkio_cgroup {
  41         struct cgroup_subsys_state css;
  42         spinlock_t lock;
  43         struct hlist_head blkg_list;
  44
  45         /* for policies to test whether associated blkcg has changed */
  46         uint64_t id;
  47
  48         /* TODO: per-policy storage in blkio_cgroup */
  49         unsigned int cfq_weight;        /* belongs to cfq */
  50 };
  51
  52 struct blkg_stat {
  53         struct u64_stats_sync           syncp;
  54         uint64_t                        cnt;
  55 };
  56
  57 struct blkg_rwstat {
  58         struct u64_stats_sync           syncp;
  59         uint64_t                        cnt[BLKG_RWSTAT_NR];
  60 };
  61
  62 /* per-blkg per-policy data */
  63 struct blkg_policy_data {
  64         /* the blkg this per-policy data belongs to */
  65         struct blkio_group *blkg;
  66
  67         /* pol->pdata_size bytes of private data used by policy impl */
  68         char pdata[] __aligned(__alignof__(unsigned long long));
  69 };
  70
  71 struct blkio_group {
  72         /* Pointer to the associated request_queue */
  73         struct request_queue *q;
  74         struct list_head q_node;
  75         struct hlist_node blkcg_node;
  76         struct blkio_cgroup *blkcg;
  77         /* Store cgroup path */
  78         char path[128];
  79         /* reference count */
  80         int refcnt;
  81
  82         struct blkg_policy_data *pd[BLKCG_MAX_POLS];
  83
  84         struct rcu_head rcu_head;
  85 };
  86
  87 typedef void (blkio_init_group_fn)(struct blkio_group *blkg);
  88 typedef void (blkio_exit_group_fn)(struct blkio_group *blkg);
  89 typedef void (blkio_reset_group_stats_fn)(struct blkio_group *blkg);
  90
  91 struct blkio_policy_ops {
  92         blkio_init_group_fn *blkio_init_group_fn;
  93         blkio_exit_group_fn *blkio_exit_group_fn;
  94         blkio_reset_group_stats_fn *blkio_reset_group_stats_fn;
  95 };
  96
  97 struct blkio_policy_type {
  98         struct blkio_policy_ops ops;
  99         int plid;
 100         size_t pdata_size;              /* policy specific private data size */
 101         struct cftype *cftypes;         /* cgroup files for the policy */
 102 };
 103
 104 extern int blkcg_init_queue(struct request_queue *q);
 105 extern void blkcg_drain_queue(struct request_queue *q);
 106 extern void blkcg_exit_queue(struct request_queue *q);
 107
 108 /* Blkio controller policy registration */
 109 extern int blkio_policy_register(struct blkio_policy_type *);
 110 extern void blkio_policy_unregister(struct blkio_policy_type *);
 111 extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);
 112 extern void update_root_blkg_pd(struct request_queue *q,
 113                                 const struct blkio_policy_type *pol);
 114
 115 void blkcg_print_blkgs(struct seq_file *sf, struct blkio_cgroup *blkcg,
 116                        u64 (*prfill)(struct seq_file *, void *, int),
 117                        const struct blkio_policy_type *pol, int data,
 118                        bool show_total);
 119 u64 __blkg_prfill_u64(struct seq_file *sf, void *pdata, u64 v);
 120 u64 __blkg_prfill_rwstat(struct seq_file *sf, void *pdata,
 121                          const struct blkg_rwstat *rwstat);
 122 u64 blkg_prfill_stat(struct seq_file *sf, void *pdata, int off);
 123 u64 blkg_prfill_rwstat(struct seq_file *sf, void *pdata, int off);
 124
 125 struct blkg_conf_ctx {
 126         struct gendisk          *disk;
 127         struct blkio_group      *blkg;
 128         u64                     v;
 129 };
 130
 131 int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input,
 132                    struct blkg_conf_ctx *ctx);
 133 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 134
 135
 136 /**
 137  * blkg_to_pdata - get policy private data
 138  * @blkg: blkg of interest
 139  * @pol: policy of interest
 140  *
 141  * Return pointer to private data associated with the @blkg-@pol pair.
 142  */
 143 static inline void *blkg_to_pdata(struct blkio_group *blkg,
 144                               struct blkio_policy_type *pol)
 145 {
 146         return blkg ? blkg->pd[pol->plid]->pdata : NULL;
 147 }
 148
 149 /**
 150  * pdata_to_blkg - get blkg associated with policy private data
 151  * @pdata: policy private data of interest
 152  *
 153  * @pdata is policy private data.  Determine the blkg it's associated with.
 154  */
 155 static inline struct blkio_group *pdata_to_blkg(void *pdata)
 156 {
 157         if (pdata) {
 158                 struct blkg_policy_data *pd =
 159                         container_of(pdata, struct blkg_policy_data, pdata);
 160                 return pd->blkg;
 161         }
 162         return NULL;
 163 }
 164
 165 static inline char *blkg_path(struct blkio_group *blkg)
 166 {
 167         return blkg->path;
 168 }
 169
 170 /**
 171  * blkg_get - get a blkg reference
 172  * @blkg: blkg to get
 173  *
 174  * The caller should be holding queue_lock and an existing reference.
 175  */
 176 static inline void blkg_get(struct blkio_group *blkg)
 177 {
 178         lockdep_assert_held(blkg->q->queue_lock);
 179         WARN_ON_ONCE(!blkg->refcnt);
 180         blkg->refcnt++;
 181 }
 182
 183 void __blkg_release(struct blkio_group *blkg);
 184
 185 /**
 186  * blkg_put - put a blkg reference
 187  * @blkg: blkg to put
 188  *
 189  * The caller should be holding queue_lock.
 190  */
 191 static inline void blkg_put(struct blkio_group *blkg)
 192 {
 193         lockdep_assert_held(blkg->q->queue_lock);
 194         WARN_ON_ONCE(blkg->refcnt <= 0);
 195         if (!--blkg->refcnt)
 196                 __blkg_release(blkg);
 197 }
 198
 199 /**
 200  * blkg_stat_add - add a value to a blkg_stat
 201  * @stat: target blkg_stat
 202  * @val: value to add
 203  *
 204  * Add @val to @stat.  The caller is responsible for synchronizing calls to
 205  * this function.
 206  */
 207 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 208 {
 209         u64_stats_update_begin(&stat->syncp);
 210         stat->cnt += val;
 211         u64_stats_update_end(&stat->syncp);
 212 }
 213
 214 /**
 215  * blkg_stat_read - read the current value of a blkg_stat
 216  * @stat: blkg_stat to read
 217  *
 218  * Read the current value of @stat.  This function can be called without
 219  * synchroniztion and takes care of u64 atomicity.
 220  */
 221 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 222 {
 223         unsigned int start;
 224         uint64_t v;
 225
 226         do {
 227                 start = u64_stats_fetch_begin(&stat->syncp);
 228                 v = stat->cnt;
 229         } while (u64_stats_fetch_retry(&stat->syncp, start));
 230
 231         return v;
 232 }
 233
 234 /**
 235  * blkg_stat_reset - reset a blkg_stat
 236  * @stat: blkg_stat to reset
 237  */
 238 static inline void blkg_stat_reset(struct blkg_stat *stat)
 239 {
 240         stat->cnt = 0;
 241 }
 242
 243 /**
 244  * blkg_rwstat_add - add a value to a blkg_rwstat
 245  * @rwstat: target blkg_rwstat
 246  * @rw: mask of REQ_{WRITE|SYNC}
 247  * @val: value to add
 248  *
 249  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 250  * caller is responsible for synchronizing calls to this function.
 251  */
 252 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 253                                    int rw, uint64_t val)
 254 {
 255         u64_stats_update_begin(&rwstat->syncp);
 256
 257         if (rw & REQ_WRITE)
 258                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 259         else
 260                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 261         if (rw & REQ_SYNC)
 262                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 263         else
 264                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 265
 266         u64_stats_update_end(&rwstat->syncp);
 267 }
 268
 269 /**
 270  * blkg_rwstat_read - read the current values of a blkg_rwstat
 271  * @rwstat: blkg_rwstat to read
 272  *
 273  * Read the current snapshot of @rwstat and return it as the return value.
 274  * This function can be called without synchronization and takes care of
 275  * u64 atomicity.
 276  */
 277 static struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 278 {
 279         unsigned int start;
 280         struct blkg_rwstat tmp;
 281
 282         do {
 283                 start = u64_stats_fetch_begin(&rwstat->syncp);
 284                 tmp = *rwstat;
 285         } while (u64_stats_fetch_retry(&rwstat->syncp, start));
 286
 287         return tmp;
 288 }
 289
 290 /**
 291  * blkg_rwstat_sum - read the total count of a blkg_rwstat
 292  * @rwstat: blkg_rwstat to read
 293  *
 294  * Return the total count of @rwstat regardless of the IO direction.  This
 295  * function can be called without synchronization and takes care of u64
 296  * atomicity.
 297  */
 298 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
 299 {
 300         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 301
 302         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 303 }
 304
 305 /**
 306  * blkg_rwstat_reset - reset a blkg_rwstat
 307  * @rwstat: blkg_rwstat to reset
 308  */
 309 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 310 {
 311         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 312 }
 313
 314 #else
 315
 316 struct blkio_group {
 317 };
 318
 319 struct blkio_policy_type {
 320 };
 321
 322 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 323 static inline void blkcg_drain_queue(struct request_queue *q) { }
 324 static inline void blkcg_exit_queue(struct request_queue *q) { }
 325 static inline int blkio_policy_register(struct blkio_policy_type *blkiop) { return 0; }
 326 static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
 327 static inline void blkg_destroy_all(struct request_queue *q,
 328                                     bool destory_root) { }
 329 static inline void update_root_blkg_pd(struct request_queue *q,
 330                                        const struct blkio_policy_type *pol) { }
 331
 332 static inline void *blkg_to_pdata(struct blkio_group *blkg,
 333                                 struct blkio_policy_type *pol) { return NULL; }
 334 static inline struct blkio_group *pdata_to_blkg(void *pdata,
 335                                 struct blkio_policy_type *pol) { return NULL; }
 336 static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
 337 static inline void blkg_get(struct blkio_group *blkg) { }
 338 static inline void blkg_put(struct blkio_group *blkg) { }
 339
 340 #endif
 341
 342 #ifdef CONFIG_BLK_CGROUP
 343 extern struct blkio_cgroup blkio_root_cgroup;
 344 extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
 345 extern struct blkio_cgroup *bio_blkio_cgroup(struct bio *bio);
 346 extern struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
 347                                        struct request_queue *q);
 348 struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg,
 349                                        struct request_queue *q,
 350                                        bool for_root);
 351 #else
 352 struct cgroup;
 353 static inline struct blkio_cgroup *
 354 cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
 355 static inline struct blkio_cgroup *
 356 bio_blkio_cgroup(struct bio *bio) { return NULL; }
 357
 358 static inline struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
 359                                               void *key) { return NULL; }
 360 #endif
 361 #endif /* _BLK_CGROUP_H */