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         /*
  18          * q_node and ioc_node link io_cq through icq_list of q and ioc
  19          * respectively.  Both fields are unused once ioc_exit_icq() is
  20          * called and shared with __rcu_icq_cache and __rcu_head which are
  21          * used for RCU free of io_cq.
  22          */
  23         union {
  24                 struct list_head        q_node;
  25                 struct kmem_cache       *__rcu_icq_cache;
  26         };
  27         union {
  28                 struct hlist_node       ioc_node;
  29                 struct rcu_head         __rcu_head;
  30         };
  31
  32         unsigned long           changed;
  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
  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  icq_tree;
  55         struct io_cq __rcu      *icq_hint;
  56         struct hlist_head       icq_list;
  57
  58         struct work_struct release_work;
  59 };
  60
  61 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  62 {
  63         /*
  64          * if ref count is zero, don't allow sharing (ioc is going away, it's
  65          * a race).
  66          */
  67         if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  68                 atomic_inc(&ioc->nr_tasks);
  69                 return ioc;
  70         }
  71
  72         return NULL;
  73 }
  74
  75 struct task_struct;
  76 #ifdef CONFIG_BLOCK
  77 void put_io_context(struct io_context *ioc, struct request_queue *locked_q);
  78 void exit_io_context(struct task_struct *task);
  79 struct io_context *get_task_io_context(struct task_struct *task,
  80                                        gfp_t gfp_flags, int node);
  81 void ioc_ioprio_changed(struct io_context *ioc, int ioprio);
  82 void ioc_cgroup_changed(struct io_context *ioc);
  83 #else
  84 struct io_context;
  85 static inline void put_io_context(struct io_context *ioc,
  86                                   struct request_queue *locked_q) { }
  87 static inline void exit_io_context(struct task_struct *task) { }
  88 #endif
  89
  90 #endif