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 #include <linux/workqueue.h>
   7
   8 enum {
   9         ICQ_IOPRIO_CHANGED,
  10         ICQ_CGROUP_CHANGED,
  11 };
  12
  13 struct io_cq {
  14         struct request_queue    *q;
  15         struct io_context       *ioc;
  16
  17         struct list_head        q_node;
  18         struct hlist_node       ioc_node;
  19
  20         unsigned long           changed;
  21         struct rcu_head         rcu_head;
  22
  23         void (*exit)(struct io_cq *);
  24         void (*release)(struct io_cq *);
  25 };
  26
  27 /*
  28  * I/O subsystem state of the associated processes.  It is refcounted
  29  * and kmalloc'ed. These could be shared between processes.
  30  */
  31 struct io_context {
  32         atomic_long_t refcount;
  33         atomic_t nr_tasks;
  34
  35         /* all the fields below are protected by this lock */
  36         spinlock_t lock;
  37
  38         unsigned short ioprio;
  39
  40         /*
  41          * For request batching
  42          */
  43         int nr_batch_requests;     /* Number of requests left in the batch */
  44         unsigned long last_waited; /* Time last woken after wait for request */
  45
  46         struct radix_tree_root  icq_tree;
  47         struct io_cq __rcu      *icq_hint;
  48         struct hlist_head       icq_list;
  49
  50         struct work_struct release_work;
  51 };
  52
  53 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  54 {
  55         /*
  56          * if ref count is zero, don't allow sharing (ioc is going away, it's
  57          * a race).
  58          */
  59         if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  60                 atomic_inc(&ioc->nr_tasks);
  61                 return ioc;
  62         }
  63
  64         return NULL;
  65 }
  66
  67 struct task_struct;
  68 #ifdef CONFIG_BLOCK
  69 void put_io_context(struct io_context *ioc, struct request_queue *locked_q);
  70 void exit_io_context(struct task_struct *task);
  71 struct io_context *get_task_io_context(struct task_struct *task,
  72                                        gfp_t gfp_flags, int node);
  73 void ioc_ioprio_changed(struct io_context *ioc, int ioprio);
  74 void ioc_cgroup_changed(struct io_context *ioc);
  75 #else
  76 struct io_context;
  77 static inline void put_io_context(struct io_context *ioc,
  78                                   struct request_queue *locked_q) { }
  79 static inline void exit_io_context(struct task_struct *task) { }
  80 #endif
  81
  82 #endif