Quelle blk-cgroup.h Sprache: C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BLK_CGROUP_PRIVATE_H
#define _BLK_CGROUP_PRIVATE_H
/*
* block cgroup private header
*
* Based on ideas and code from CFQ, CFS and BFQ:
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
*
* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
*       Paolo Valente <paolo.valente@unimore.it>
*
* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
*               Nauman Rafique <nauman@google.com>
*/

#include <linux/blk-cgroup.h>
#include <linux/cgroup.h>
#include <linux/kthread.h>
#include <linux/blk-mq.h>
#include <linux/llist.h>
#include "blk.h"

struct blkcg_gq;
struct blkg_policy_data;

/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
#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 blkcg_gq         *blkg;
struct llist_node  lnode;
int    lqueued; /* queued in llist */
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];
#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;
};

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;
refcount_t   online_pin;
/* If there is block congestion on this cgroup. */
atomic_t   congestion_count;

struct radix_tree_root  blkg_tree;
struct blkcg_gq __rcu  *blkg_hint;
struct hlist_head  blkg_list;

struct blkcg_policy_data *cpd[BLKCG_MAX_POLS];

struct list_head  all_blkcgs_node;

/*
* List of updated percpu blkg_iostat_set's since the last flush.
*/
struct llist_head __percpu *lhead;

#ifdef CONFIG_BLK_CGROUP_FC_APPID
char                            fc_app_id[FC_APPID_LEN];
#endif
#ifdef CONFIG_CGROUP_WRITEBACK
struct list_head  cgwb_list;
#endif
};

static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
{
return css ? container_of(css, struct blkcg, css) : NULL;
}

/*
* A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
* request_queue (q).  This is used by blkcg policies which need to track
* information per blkcg - q pair.
*
* There can be multiple active blkcg policies and each blkg:policy pair is
* represented by a blkg_policy_data which is allocated and freed by each
* policy's pd_alloc/free_fn() methods.  A policy can allocate private data
* area by allocating larger data structure which embeds blkg_policy_data
* at the beginning.
*/
struct blkg_policy_data {
/* the blkg and policy id this per-policy data belongs to */
struct blkcg_gq   *blkg;
int    plid;
bool    online;
};

/*
* Policies that need to keep per-blkcg data which is independent from any
* request_queue associated to it should implement cpd_alloc/free_fn()
* methods.  A policy can allocate private data area by allocating larger
* data structure which embeds blkcg_policy_data at the beginning.
* cpd_init() is invoked to let each policy handle per-blkcg data.
*/
struct blkcg_policy_data {
/* the blkcg and policy id this per-policy data belongs to */
struct blkcg   *blkcg;
int    plid;
};

typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(struct gendisk *disk,
  struct blkcg *blkcg, gfp_t gfp);
typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd,
    struct seq_file *s);

struct blkcg_policy {
int    plid;
/* cgroup files for the policy */
struct cftype   *dfl_cftypes;
struct cftype   *legacy_cftypes;

/* operations */
blkcg_pol_alloc_cpd_fn  *cpd_alloc_fn;
blkcg_pol_free_cpd_fn  *cpd_free_fn;

blkcg_pol_alloc_pd_fn  *pd_alloc_fn;
blkcg_pol_init_pd_fn  *pd_init_fn;
blkcg_pol_online_pd_fn  *pd_online_fn;
blkcg_pol_offline_pd_fn  *pd_offline_fn;
blkcg_pol_free_pd_fn  *pd_free_fn;
blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
blkcg_pol_stat_pd_fn  *pd_stat_fn;
};

extern struct blkcg blkcg_root;
extern bool blkcg_debug_stats;

void blkg_init_queue(struct request_queue *q);
int blkcg_init_disk(struct gendisk *disk);
void blkcg_exit_disk(struct gendisk *disk);

/* Blkio controller policy registration */
int blkcg_policy_register(struct blkcg_policy *pol);
void blkcg_policy_unregister(struct blkcg_policy *pol);
int blkcg_activate_policy(struct gendisk *disk, const struct blkcg_policy *pol);
void blkcg_deactivate_policy(struct gendisk *disk,
        const struct blkcg_policy *pol);

const char *blkg_dev_name(struct blkcg_gq *blkg);
void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
         u64 (*prfill)(struct seq_file *,
         struct blkg_policy_data *, int),
         const struct blkcg_policy *pol, int data,
         bool show_total);
u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);

struct blkg_conf_ctx {
char    *input;
char    *body;
struct block_device  *bdev;
struct blkcg_gq   *blkg;
};

void blkg_conf_init(struct blkg_conf_ctx *ctx, char *input);
int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx);
unsigned long blkg_conf_open_bdev_frozen(struct blkg_conf_ctx *ctx);
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
     struct blkg_conf_ctx *ctx);
void blkg_conf_exit(struct blkg_conf_ctx *ctx);
void blkg_conf_exit_frozen(struct blkg_conf_ctx *ctx, unsigned long memflags);

/**
* bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
* @bio: the target &bio
*
* Return: true if this bio needs to be submitted with the root blkg context.
*
* 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_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)
{
return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
}

/**
* blkg_lookup - lookup blkg for the specified blkcg - q pair
* @blkcg: blkcg of interest
* @q: request_queue of interest
*
* Lookup blkg for the @blkcg - @q pair.
*
* Must be called in a RCU critical section.
*/
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
        struct request_queue *q)
{
struct blkcg_gq *blkg;

if (blkcg == &blkcg_root)
  return q->root_blkg;

blkg = rcu_dereference_check(blkcg->blkg_hint,
   lockdep_is_held(&q->queue_lock));
if (blkg && blkg->q == q)
  return blkg;

blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
if (blkg && blkg->q != q)
  blkg = NULL;
return blkg;
}

/**
* blkg_to_pd - get policy private data
* @blkg: blkg of interest
* @pol: policy of interest
*
* Return pointer to private data associated with the @blkg-@pol pair.
*/
static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
        struct blkcg_policy *pol)
{
return blkg ? blkg->pd[pol->plid] : NULL;
}

static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
           struct blkcg_policy *pol)
{
return blkcg ? blkcg->cpd[pol->plid] : NULL;
}

/**
* pd_to_blkg - get blkg associated with policy private data
* @pd: policy private data of interest
*
* @pd is policy private data.  Determine the blkg it's associated with.
*/
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
{
return pd ? pd->blkg : NULL;
}

static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
{
return cpd ? cpd->blkcg : NULL;
}

/**
* blkg_get - get a blkg reference
* @blkg: blkg to get
*
* The caller should be holding an existing reference.
*/
static inline void blkg_get(struct blkcg_gq *blkg)
{
percpu_ref_get(&blkg->refcnt);
}

/**
* blkg_tryget - try and get a blkg reference
* @blkg: blkg to get
*
* This is for use when doing an RCU lookup of the blkg.  We may be in the midst
* of freeing this blkg, so we can only use it if the refcnt is not zero.
*/
static inline bool blkg_tryget(struct blkcg_gq *blkg)
{
return blkg && percpu_ref_tryget(&blkg->refcnt);
}

/**
* blkg_put - put a blkg reference
* @blkg: blkg to put
*/
static inline void blkg_put(struct blkcg_gq *blkg)
{
percpu_ref_put(&blkg->refcnt);
}

/**
* blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
* @d_blkg: loop cursor pointing to the current descendant
* @pos_css: used for iteration
* @p_blkg: target blkg to walk descendants of
*
* Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
* read locked.  If called under either blkcg or queue lock, the iteration
* is guaranteed to include all and only online blkgs.  The caller may
* update @pos_css by calling css_rightmost_descendant() to skip subtree.
* @p_blkg is included in the iteration and the first node to be visited.
*/
#define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)  \
css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
  if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
         (p_blkg)->q)))

/**
* blkg_for_each_descendant_post - post-order walk of a blkg's descendants
* @d_blkg: loop cursor pointing to the current descendant
* @pos_css: used for iteration
* @p_blkg: target blkg to walk descendants of
*
* Similar to blkg_for_each_descendant_pre() but performs post-order
* traversal instead.  Synchronization rules are the same.  @p_blkg is
* included in the iteration and the last node to be visited.
*/
#define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)  \
css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
  if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \
         (p_blkg)->q)))

static inline void blkcg_use_delay(struct blkcg_gq *blkg)
{
if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0))
  return;
if (atomic_add_return(1, &blkg->use_delay) == 1)
  atomic_inc(&blkg->blkcg->congestion_count);
}

static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
{
int old = atomic_read(&blkg->use_delay);

if (WARN_ON_ONCE(old < 0))
  return 0;
if (old == 0)
  return 0;

/*
* We do this song and dance because we can race with somebody else
* adding or removing delay.  If we just did an atomic_dec we'd end up
* negative and we'd already be in trouble.  We need to subtract 1 and
* then check to see if we were the last delay so we can drop the
* congestion count on the cgroup.
*/
while (old && !atomic_try_cmpxchg(&blkg->use_delay, &old, old - 1))
  ;

if (old == 0)
  return 0;
if (old == 1)
  atomic_dec(&blkg->blkcg->congestion_count);
return 1;
}

/**
* blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount
* @blkg: target blkg
* @delay: delay duration in nsecs
*
* When enabled with this function, the delay is not decayed and must be
* explicitly cleared with blkcg_clear_delay(). Must not be mixed with
* blkcg_[un]use_delay() and blkcg_add_delay() usages.
*/
static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay)
{
int old = atomic_read(&blkg->use_delay);

/* We only want 1 person setting the congestion count for this blkg. */
if (!old && atomic_try_cmpxchg(&blkg->use_delay, &old, -1))
  atomic_inc(&blkg->blkcg->congestion_count);

atomic64_set(&blkg->delay_nsec, delay);
}

/**
* blkcg_clear_delay - Disable allocator delay mechanism
* @blkg: target blkg
*
* Disable use_delay mechanism. See blkcg_set_delay().
*/
static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
{
int old = atomic_read(&blkg->use_delay);

/* We only want 1 person clearing the congestion count for this blkg. */
if (old && atomic_try_cmpxchg(&blkg->use_delay, &old, 0))
  atomic_dec(&blkg->blkcg->congestion_count);
}

/**
* blk_cgroup_mergeable - Determine whether to allow or disallow merges
* @rq: request to merge into
* @bio: bio to merge
*
* @bio and @rq should belong to the same cgroup and their issue_as_root should
* match. The latter is necessary as we don't want to throttle e.g. a metadata
* update because it happens to be next to a regular IO.
*/
static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio)
{
return rq->bio->bi_blkg == bio->bi_blkg &&
  bio_issue_as_root_blkg(rq->bio) == bio_issue_as_root_blkg(bio);
}

static inline bool blkcg_policy_enabled(struct request_queue *q,
    const struct blkcg_policy *pol)
{
return pol && test_bit(pol->plid, q->blkcg_pols);
}

void blk_cgroup_bio_start(struct bio *bio);
void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
#else /* CONFIG_BLK_CGROUP */

struct blkg_policy_data {
};

struct blkcg_policy_data {
};

struct blkcg_policy {
};

struct blkcg {
};

static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
static inline void blkg_init_queue(struct request_queue *q) { }
static inline int blkcg_init_disk(struct gendisk *disk) { return 0; }
static inline void blkcg_exit_disk(struct gendisk *disk) { }
static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
static inline int blkcg_activate_policy(struct gendisk *disk,
     const struct blkcg_policy *pol) { return 0; }
static inline void blkcg_deactivate_policy(struct gendisk *disk,
        const struct blkcg_policy *pol) { }

static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
        struct blkcg_policy *pol) { return NULL; }
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
static inline void blkg_get(struct blkcg_gq *blkg) { }
static inline void blkg_put(struct blkcg_gq *blkg) { }
static inline void blk_cgroup_bio_start(struct bio *bio) { }
static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; }

#define blk_queue_for_each_rl(rl, q) \
for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)

#endif /* CONFIG_BLK_CGROUP */

#endif /* _BLK_CGROUP_PRIVATE_H */

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