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
   7struct cfq_queue;
   8struct cfq_io_context {
   9        void *key;
  10
  11        struct cfq_queue *cfqq[2];
  12
  13        struct io_context *ioc;
  14
  15        unsigned long last_end_request;
  16
  17        unsigned long ttime_total;
  18        unsigned long ttime_samples;
  19        unsigned long ttime_mean;
  20
  21        struct list_head queue_list;
  22        struct hlist_node cic_list;
  23
  24        void (*dtor)(struct io_context *); /* destructor */
  25        void (*exit)(struct io_context *); /* called on task exit */
  26
  27        struct rcu_head rcu_head;
  28};
  29
  30/*
  31 * I/O subsystem state of the associated processes.  It is refcounted
  32 * and kmalloc'ed. These could be shared between processes.
  33 */
  34struct io_context {
  35        atomic_long_t refcount;
  36        atomic_t nr_tasks;
  37
  38        /* all the fields below are protected by this lock */
  39        spinlock_t lock;
  40
  41        unsigned short ioprio;
  42        unsigned short ioprio_changed;
  43
  44#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
  45        unsigned short cgroup_changed;
  46#endif
  47
  48        /*
  49         * For request batching
  50         */
  51        int nr_batch_requests;     /* Number of requests left in the batch */
  52        unsigned long last_waited; /* Time last woken after wait for request */
  53
  54        struct radix_tree_root radix_root;
  55        struct hlist_head cic_list;
  56        void __rcu *ioc_data;
  57};
  58
  59static inline struct io_context *ioc_task_link(struct io_context *ioc)
  60{
  61        /*
  62         * if ref count is zero, don't allow sharing (ioc is going away, it's
  63         * a race).
  64         */
  65        if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  66                atomic_inc(&ioc->nr_tasks);
  67                return ioc;
  68        }
  69
  70        return NULL;
  71}
  72
  73struct task_struct;
  74#ifdef CONFIG_BLOCK
  75int put_io_context(struct io_context *ioc);
  76void exit_io_context(struct task_struct *task);
  77struct io_context *get_io_context(gfp_t gfp_flags, int node);
  78struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
  79#else
  80static inline void exit_io_context(struct task_struct *task)
  81{
  82}
  83
  84struct io_context;
  85static inline int put_io_context(struct io_context *ioc)
  86{
  87        return 1;
  88}
  89#endif
  90
  91#endif
  92