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         unsigned long dead_key;
  11
  12         struct cfq_queue *cfqq[2];
  13
  14         struct io_context *ioc;
  15
  16         unsigned long last_end_request;
  17
  18         unsigned long ttime_total;
  19         unsigned long ttime_samples;
  20         unsigned long ttime_mean;
  21
  22         struct list_head queue_list;
  23         struct hlist_node cic_list;
  24
  25         void (*dtor)(struct io_context *); /* destructor */
  26         void (*exit)(struct io_context *); /* called on task exit */
  27
  28         struct rcu_head rcu_head;
  29 };
  30
  31 /*
  32  * I/O subsystem state of the associated processes.  It is refcounted
  33  * and kmalloc'ed. These could be shared between processes.
  34  */
  35 struct io_context {
  36         atomic_long_t refcount;
  37         atomic_t nr_tasks;
  38
  39         /* all the fields below are protected by this lock */
  40         spinlock_t lock;
  41
  42         unsigned short ioprio;
  43         unsigned short ioprio_changed;
  44
  45 #ifdef CONFIG_BLK_CGROUP
  46         unsigned short cgroup_changed;
  47 #endif
  48
  49         /*
  50          * For request batching
  51          */
  52         unsigned long last_waited; /* Time last woken after wait for request */
  53         int nr_batch_requests;     /* Number of requests left in the batch */
  54
  55         struct radix_tree_root radix_root;
  56         struct hlist_head cic_list;
  57         void *ioc_data;
  58 };
  59
  60 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  61 {
  62         /*
  63          * if ref count is zero, don't allow sharing (ioc is going away, it's
  64          * a race).
  65          */
  66         if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  67                 atomic_inc(&ioc->nr_tasks);
  68                 return ioc;
  69         }
  70
  71         return NULL;
  72 }
  73
  74 struct task_struct;
  75 #ifdef CONFIG_BLOCK
  76 int put_io_context(struct io_context *ioc);
  77 void exit_io_context(struct task_struct *task);
  78 struct io_context *get_io_context(gfp_t gfp_flags, int node);
  79 struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
  80 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
  81 #else
  82 static inline void exit_io_context(struct task_struct *task)
  83 {
  84 }
  85
  86 struct io_context;
  87 static inline int put_io_context(struct io_context *ioc)
  88 {
  89         return 1;
  90 }
  91 #endif
  92
  93 #endif