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