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 enum blkio_policy_id {
  21         BLKIO_POLICY_PROP = 0,          /* Proportional Bandwidth division */
  22         BLKIO_POLICY_THROTL,            /* Throttling */
  23
  24         BLKIO_NR_POLICIES,
  25 };
  26
  27 /* Max limits for throttle policy */
  28 #define THROTL_IOPS_MAX         UINT_MAX
  29
  30 #ifdef CONFIG_BLK_CGROUP
  31
  32 /* CFQ specific, out here for blkcg->cfq_weight */
  33 #define CFQ_WEIGHT_MIN          10
  34 #define CFQ_WEIGHT_MAX          1000
  35 #define CFQ_WEIGHT_DEFAULT      500
  36
  37 /* cft->private [un]packing for stat printing */
  38 #define BLKCG_STAT_PRIV(pol, off)       (((unsigned)(pol) << 16) | (off))
  39 #define BLKCG_STAT_POL(prv)             ((unsigned)(prv) >> 16)
  40 #define BLKCG_STAT_OFF(prv)             ((unsigned)(prv) & 0xffff)
  41
  42 enum blkg_rwstat_type {
  43         BLKG_RWSTAT_READ,
  44         BLKG_RWSTAT_WRITE,
  45         BLKG_RWSTAT_SYNC,
  46         BLKG_RWSTAT_ASYNC,
  47
  48         BLKG_RWSTAT_NR,
  49         BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
  50 };
  51
  52 struct blkio_cgroup {
  53         struct cgroup_subsys_state css;
  54         spinlock_t lock;
  55         struct hlist_head blkg_list;
  56
  57         /* for policies to test whether associated blkcg has changed */
  58         uint64_t id;
  59
  60         /* TODO: per-policy storage in blkio_cgroup */
  61         unsigned int cfq_weight;        /* belongs to cfq */
  62 };
  63
  64 struct blkg_stat {
  65         struct u64_stats_sync           syncp;
  66         uint64_t                        cnt;
  67 };
  68
  69 struct blkg_rwstat {
  70         struct u64_stats_sync           syncp;
  71         uint64_t                        cnt[BLKG_RWSTAT_NR];
  72 };
  73
  74 /* per-blkg per-policy data */
  75 struct blkg_policy_data {
  76         /* the blkg this per-policy data belongs to */
  77         struct blkio_group *blkg;
  78
  79         /* pol->pdata_size bytes of private data used by policy impl */
  80         char pdata[] __aligned(__alignof__(unsigned long long));
  81 };
  82
  83 struct blkio_group {
  84         /* Pointer to the associated request_queue */
  85         struct request_queue *q;
  86         struct list_head q_node;
  87         struct hlist_node blkcg_node;
  88         struct blkio_cgroup *blkcg;
  89         /* Store cgroup path */
  90         char path[128];
  91         /* reference count */
  92         int refcnt;
  93
  94         struct blkg_policy_data *pd[BLKIO_NR_POLICIES];
  95
  96         struct rcu_head rcu_head;
  97 };
  98
  99 typedef void (blkio_init_group_fn)(struct blkio_group *blkg);
 100 typedef void (blkio_exit_group_fn)(struct blkio_group *blkg);
 101 typedef void (blkio_reset_group_stats_fn)(struct blkio_group *blkg);
 102
 103 struct blkio_policy_ops {
 104         blkio_init_group_fn *blkio_init_group_fn;
 105         blkio_exit_group_fn *blkio_exit_group_fn;
 106         blkio_reset_group_stats_fn *blkio_reset_group_stats_fn;
 107 };
 108
 109 struct blkio_policy_type {
 110         struct list_head list;
 111         struct blkio_policy_ops ops;
 112         enum blkio_policy_id plid;
 113         size_t pdata_size;              /* policy specific private data size */
 114         struct cftype *cftypes;         /* cgroup files for the policy */
 115 };
 116
 117 extern int blkcg_init_queue(struct request_queue *q);
 118 extern void blkcg_drain_queue(struct request_queue *q);
 119 extern void blkcg_exit_queue(struct request_queue *q);
 120
 121 /* Blkio controller policy registration */
 122 extern void blkio_policy_register(struct blkio_policy_type *);
 123 extern void blkio_policy_unregister(struct blkio_policy_type *);
 124 extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);
 125 extern void update_root_blkg_pd(struct request_queue *q,
 126                                 enum blkio_policy_id plid);
 127
 128 void blkcg_print_blkgs(struct seq_file *sf, struct blkio_cgroup *blkcg,
 129                        u64 (*prfill)(struct seq_file *, void *, int),
 130                        int pol, int data, bool show_total);
 131 u64 __blkg_prfill_u64(struct seq_file *sf, void *pdata, u64 v);
 132 u64 __blkg_prfill_rwstat(struct seq_file *sf, void *pdata,
 133                          const struct blkg_rwstat *rwstat);
 134 int blkcg_print_stat(struct cgroup *cgrp, struct cftype *cft,
 135                      struct seq_file *sf);
 136 int blkcg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
 137                        struct seq_file *sf);
 138
 139 struct blkg_conf_ctx {
 140         struct gendisk          *disk;
 141         struct blkio_group      *blkg;
 142         u64                     v;
 143 };
 144
 145 int blkg_conf_prep(struct blkio_cgroup *blkcg, const char *input,
 146                    struct blkg_conf_ctx *ctx);
 147 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 148
 149
 150 /**
 151  * blkg_to_pdata - get policy private data
 152  * @blkg: blkg of interest
 153  * @pol: policy of interest
 154  *
 155  * Return pointer to private data associated with the @blkg-@pol pair.
 156  */
 157 static inline void *blkg_to_pdata(struct blkio_group *blkg,
 158                               struct blkio_policy_type *pol)
 159 {
 160         return blkg ? blkg->pd[pol->plid]->pdata : NULL;
 161 }
 162
 163 /**
 164  * pdata_to_blkg - get blkg associated with policy private data
 165  * @pdata: policy private data of interest
 166  *
 167  * @pdata is policy private data.  Determine the blkg it's associated with.
 168  */
 169 static inline struct blkio_group *pdata_to_blkg(void *pdata)
 170 {
 171         if (pdata) {
 172                 struct blkg_policy_data *pd =
 173                         container_of(pdata, struct blkg_policy_data, pdata);
 174                 return pd->blkg;
 175         }
 176         return NULL;
 177 }
 178
 179 static inline char *blkg_path(struct blkio_group *blkg)
 180 {
 181         return blkg->path;
 182 }
 183
 184 /**
 185  * blkg_get - get a blkg reference
 186  * @blkg: blkg to get
 187  *
 188  * The caller should be holding queue_lock and an existing reference.
 189  */
 190 static inline void blkg_get(struct blkio_group *blkg)
 191 {
 192         lockdep_assert_held(blkg->q->queue_lock);
 193         WARN_ON_ONCE(!blkg->refcnt);
 194         blkg->refcnt++;
 195 }
 196
 197 void __blkg_release(struct blkio_group *blkg);
 198
 199 /**
 200  * blkg_put - put a blkg reference
 201  * @blkg: blkg to put
 202  *
 203  * The caller should be holding queue_lock.
 204  */
 205 static inline void blkg_put(struct blkio_group *blkg)
 206 {
 207         lockdep_assert_held(blkg->q->queue_lock);
 208         WARN_ON_ONCE(blkg->refcnt <= 0);
 209         if (!--blkg->refcnt)
 210                 __blkg_release(blkg);
 211 }
 212
 213 /**
 214  * blkg_stat_add - add a value to a blkg_stat
 215  * @stat: target blkg_stat
 216  * @val: value to add
 217  *
 218  * Add @val to @stat.  The caller is responsible for synchronizing calls to
 219  * this function.
 220  */
 221 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 222 {
 223         u64_stats_update_begin(&stat->syncp);
 224         stat->cnt += val;
 225         u64_stats_update_end(&stat->syncp);
 226 }
 227
 228 /**
 229  * blkg_stat_read - read the current value of a blkg_stat
 230  * @stat: blkg_stat to read
 231  *
 232  * Read the current value of @stat.  This function can be called without
 233  * synchroniztion and takes care of u64 atomicity.
 234  */
 235 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 236 {
 237         unsigned int start;
 238         uint64_t v;
 239
 240         do {
 241                 start = u64_stats_fetch_begin(&stat->syncp);
 242                 v = stat->cnt;
 243         } while (u64_stats_fetch_retry(&stat->syncp, start));
 244
 245         return v;
 246 }
 247
 248 /**
 249  * blkg_stat_reset - reset a blkg_stat
 250  * @stat: blkg_stat to reset
 251  */
 252 static inline void blkg_stat_reset(struct blkg_stat *stat)
 253 {
 254         stat->cnt = 0;
 255 }
 256
 257 /**
 258  * blkg_rwstat_add - add a value to a blkg_rwstat
 259  * @rwstat: target blkg_rwstat
 260  * @rw: mask of REQ_{WRITE|SYNC}
 261  * @val: value to add
 262  *
 263  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 264  * caller is responsible for synchronizing calls to this function.
 265  */
 266 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 267                                    int rw, uint64_t val)
 268 {
 269         u64_stats_update_begin(&rwstat->syncp);
 270
 271         if (rw & REQ_WRITE)
 272                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 273         else
 274                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 275         if (rw & REQ_SYNC)
 276                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 277         else
 278                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 279
 280         u64_stats_update_end(&rwstat->syncp);
 281 }
 282
 283 /**
 284  * blkg_rwstat_read - read the current values of a blkg_rwstat
 285  * @rwstat: blkg_rwstat to read
 286  *
 287  * Read the current snapshot of @rwstat and return it as the return value.
 288  * This function can be called without synchronization and takes care of
 289  * u64 atomicity.
 290  */
 291 static struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 292 {
 293         unsigned int start;
 294         struct blkg_rwstat tmp;
 295
 296         do {
 297                 start = u64_stats_fetch_begin(&rwstat->syncp);
 298                 tmp = *rwstat;
 299         } while (u64_stats_fetch_retry(&rwstat->syncp, start));
 300
 301         return tmp;
 302 }
 303
 304 /**
 305  * blkg_rwstat_sum - read the total count of a blkg_rwstat
 306  * @rwstat: blkg_rwstat to read
 307  *
 308  * Return the total count of @rwstat regardless of the IO direction.  This
 309  * function can be called without synchronization and takes care of u64
 310  * atomicity.
 311  */
 312 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
 313 {
 314         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 315
 316         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 317 }
 318
 319 /**
 320  * blkg_rwstat_reset - reset a blkg_rwstat
 321  * @rwstat: blkg_rwstat to reset
 322  */
 323 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 324 {
 325         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 326 }
 327
 328 #else
 329
 330 struct blkio_group {
 331 };
 332
 333 struct blkio_policy_type {
 334 };
 335
 336 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 337 static inline void blkcg_drain_queue(struct request_queue *q) { }
 338 static inline void blkcg_exit_queue(struct request_queue *q) { }
 339 static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }
 340 static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
 341 static inline void blkg_destroy_all(struct request_queue *q,
 342                                     bool destory_root) { }
 343 static inline void update_root_blkg_pd(struct request_queue *q,
 344                                        enum blkio_policy_id plid) { }
 345
 346 static inline void *blkg_to_pdata(struct blkio_group *blkg,
 347                                 struct blkio_policy_type *pol) { return NULL; }
 348 static inline struct blkio_group *pdata_to_blkg(void *pdata,
 349                                 struct blkio_policy_type *pol) { return NULL; }
 350 static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
 351 static inline void blkg_get(struct blkio_group *blkg) { }
 352 static inline void blkg_put(struct blkio_group *blkg) { }
 353
 354 #endif
 355
 356 #ifdef CONFIG_BLK_CGROUP
 357 extern struct blkio_cgroup blkio_root_cgroup;
 358 extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
 359 extern struct blkio_cgroup *bio_blkio_cgroup(struct bio *bio);
 360 extern struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
 361                                        struct request_queue *q);
 362 struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg,
 363                                        struct request_queue *q,
 364                                        bool for_root);
 365 #else
 366 struct cgroup;
 367 static inline struct blkio_cgroup *
 368 cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
 369 static inline struct blkio_cgroup *
 370 bio_blkio_cgroup(struct bio *bio) { return NULL; }
 371
 372 static inline struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
 373                                               void *key) { return NULL; }
 374 #endif
 375 #endif /* _BLK_CGROUP_H */