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 enum {
  17         CIC_IOPRIO_CHANGED,
  18         CIC_CGROUP_CHANGED,
  19 };
  20
  21 struct cfq_io_context {
  22         void *key;
  23         struct request_queue *q;
  24
  25         struct cfq_queue *cfqq[2];
  26
  27         struct io_context *ioc;
  28
  29         struct cfq_ttime ttime;
  30
  31         struct list_head queue_list;
  32         struct hlist_node cic_list;
  33
  34         unsigned long changed;
  35
  36         void (*dtor)(struct io_context *); /* destructor */
  37         void (*exit)(struct io_context *); /* called on task exit */
  38
  39         struct rcu_head rcu_head;
  40 };
  41
  42 /*
  43  * I/O subsystem state of the associated processes.  It is refcounted
  44  * and kmalloc'ed. These could be shared between processes.
  45  */
  46 struct io_context {
  47         atomic_long_t refcount;
  48         atomic_t nr_tasks;
  49
  50         /* all the fields below are protected by this lock */
  51         spinlock_t lock;
  52
  53         unsigned short ioprio;
  54
  55         /*
  56          * For request batching
  57          */
  58         int nr_batch_requests;     /* Number of requests left in the batch */
  59         unsigned long last_waited; /* Time last woken after wait for request */
  60
  61         struct radix_tree_root radix_root;
  62         struct hlist_head cic_list;
  63         void __rcu *ioc_data;
  64 };
  65
  66 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  67 {
  68         /*
  69          * if ref count is zero, don't allow sharing (ioc is going away, it's
  70          * a race).
  71          */
  72         if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  73                 atomic_inc(&ioc->nr_tasks);
  74                 return ioc;
  75         }
  76
  77         return NULL;
  78 }
  79
  80 struct task_struct;
  81 #ifdef CONFIG_BLOCK
  82 void put_io_context(struct io_context *ioc);
  83 void exit_io_context(struct task_struct *task);
  84 struct io_context *get_task_io_context(struct task_struct *task,
  85                                        gfp_t gfp_flags, int node);
  86 void ioc_ioprio_changed(struct io_context *ioc, int ioprio);
  87 void ioc_cgroup_changed(struct io_context *ioc);
  88 #else
  89 struct io_context;
  90 static inline void put_io_context(struct io_context *ioc) { }
  91 static inline void exit_io_context(struct task_struct *task) { }
  92 #endif
  93
  94 #endif