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
  19         struct cfq_queue *cfqq[2];
  20
  21         struct io_context *ioc;
  22
  23         struct cfq_ttime ttime;
  24
  25         struct list_head queue_list;
  26         struct hlist_node cic_list;
  27
  28         void (*dtor)(struct io_context *); /* destructor */
  29         void (*exit)(struct io_context *); /* called on task exit */
  30
  31         struct rcu_head rcu_head;
  32 };
  33
  34 /*
  35  * I/O subsystem state of the associated processes.  It is refcounted
  36  * and kmalloc'ed. These could be shared between processes.
  37  */
  38 struct io_context {
  39         atomic_long_t refcount;
  40         atomic_t nr_tasks;
  41
  42         /* all the fields below are protected by this lock */
  43         spinlock_t lock;
  44
  45         unsigned short ioprio;
  46         unsigned short ioprio_changed;
  47
  48 #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
  49         unsigned short cgroup_changed;
  50 #endif
  51
  52         /*
  53          * For request batching
  54          */
  55         int nr_batch_requests;     /* Number of requests left in the batch */
  56         unsigned long last_waited; /* Time last woken after wait for request */
  57
  58         struct radix_tree_root radix_root;
  59         struct hlist_head cic_list;
  60         void __rcu *ioc_data;
  61 };
  62
  63 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  64 {
  65         /*
  66          * if ref count is zero, don't allow sharing (ioc is going away, it's
  67          * a race).
  68          */
  69         if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  70                 atomic_inc(&ioc->nr_tasks);
  71                 return ioc;
  72         }
  73
  74         return NULL;
  75 }
  76
  77 struct task_struct;
  78 #ifdef CONFIG_BLOCK
  79 int put_io_context(struct io_context *ioc);
  80 void exit_io_context(struct task_struct *task);
  81 struct io_context *get_io_context(gfp_t gfp_flags, int node);
  82 struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
  83 #else
  84 static inline void exit_io_context(struct task_struct *task)
  85 {
  86 }
  87
  88 struct io_context;
  89 static inline int put_io_context(struct io_context *ioc)
  90 {
  91         return 1;
  92 }
  93 #endif
  94
  95 #endif