LXR linux/include/linux/iocontext.h

   1#ifndef IOCONTEXT_H
   2#define IOCONTEXT_H
   3
   4#include <linux/radix-tree.h>
   5#include <linux/rcupdate.h>
   6
   7/*
   8 * This is the per-process anticipatory I/O scheduler state.
   9 */
  10struct as_io_context {
  11        spinlock_t lock;
  12
  13        void (*dtor)(struct as_io_context *aic); /* destructor */
  14        void (*exit)(struct as_io_context *aic); /* called on task exit */
  15
  16        unsigned long state;
  17        atomic_t nr_queued; /* queued reads & sync writes */
  18        atomic_t nr_dispatched; /* number of requests gone to the drivers */
  19
  20        /* IO History tracking */
  21        /* Thinktime */
  22        unsigned long last_end_request;
  23        unsigned long ttime_total;
  24        unsigned long ttime_samples;
  25        unsigned long ttime_mean;
  26        /* Layout pattern */
  27        unsigned int seek_samples;
  28        sector_t last_request_pos;
  29        u64 seek_total;
  30        sector_t seek_mean;
  31};
  32
  33struct cfq_queue;
  34struct cfq_io_context {
  35        void *key;
  36        unsigned long dead_key;
  37
  38        struct cfq_queue *cfqq[2];
  39
  40        struct io_context *ioc;
  41
  42        unsigned long last_end_request;
  43        sector_t last_request_pos;
  44
  45        unsigned long ttime_total;
  46        unsigned long ttime_samples;
  47        unsigned long ttime_mean;
  48
  49        unsigned int seek_samples;
  50        u64 seek_total;
  51        sector_t seek_mean;
  52
  53        struct list_head queue_list;
  54        struct hlist_node cic_list;
  55
  56        void (*dtor)(struct io_context *); /* destructor */
  57        void (*exit)(struct io_context *); /* called on task exit */
  58
  59        struct rcu_head rcu_head;
  60};
  61
  62/*
  63 * I/O subsystem state of the associated processes.  It is refcounted
  64 * and kmalloc'ed. These could be shared between processes.
  65 */
  66struct io_context {
  67        atomic_long_t refcount;
  68        atomic_t nr_tasks;
  69
  70        /* all the fields below are protected by this lock */
  71        spinlock_t lock;
  72
  73        unsigned short ioprio;
  74        unsigned short ioprio_changed;
  75
  76        /*
  77         * For request batching
  78         */
  79        unsigned long last_waited; /* Time last woken after wait for request */
  80        int nr_batch_requests;     /* Number of requests left in the batch */
  81
  82        struct as_io_context *aic;
  83        struct radix_tree_root radix_root;
  84        struct hlist_head cic_list;
  85        void *ioc_data;
  86};
  87
  88static inline struct io_context *ioc_task_link(struct io_context *ioc)
  89{
  90        /*
  91         * if ref count is zero, don't allow sharing (ioc is going away, it's
  92         * a race).
  93         */
  94        if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  95                atomic_inc(&ioc->nr_tasks);
  96                return ioc;
  97        }
  98
  99        return NULL;
 100}
 101
 102#ifdef CONFIG_BLOCK
 103int put_io_context(struct io_context *ioc);
 104void exit_io_context(void);
 105struct io_context *get_io_context(gfp_t gfp_flags, int node);
 106struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
 107void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 108#else
 109static inline void exit_io_context(void)
 110{
 111}
 112
 113struct io_context;
 114static inline int put_io_context(struct io_context *ioc)
 115{
 116        return 1;
 117}
 118#endif
 119
 120#endif
 121