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_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  */
  34 struct 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
  59 static 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
  73 struct task_struct;
  74 #ifdef CONFIG_BLOCK
  75 int put_io_context(struct io_context *ioc);
  76 void exit_io_context(struct task_struct *task);
  77 struct io_context *get_io_context(gfp_t gfp_flags, int node);
  78 struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
  79 #else
  80 static inline void exit_io_context(struct task_struct *task)
  81 {
  82 }
  83
  84 struct io_context;
  85 static inline int put_io_context(struct io_context *ioc)
  86 {
  87         return 1;
  88 }
  89 #endif
  90
  91 #endif