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 /*
   8  * This is the per-process anticipatory I/O scheduler state.
   9  */
  10 struct as_io_context {
  11         spinlock_t lock;
  12
  13         void (*dtor)(struct as_io_context *aic); /* destructor */
  14         void (*exit)(struct as_io_context *aic); /* called on task exit */
  15
  16         unsigned long state;
  17         atomic_t nr_queued; /* queued reads & sync writes */
  18         atomic_t nr_dispatched; /* number of requests gone to the drivers */
  19
  20         /* IO History tracking */
  21         /* Thinktime */
  22         unsigned long last_end_request;
  23         unsigned long ttime_total;
  24         unsigned long ttime_samples;
  25         unsigned long ttime_mean;
  26         /* Layout pattern */
  27         unsigned int seek_samples;
  28         sector_t last_request_pos;
  29         u64 seek_total;
  30         sector_t seek_mean;
  31 };
  32
  33 struct cfq_queue;
  34 struct cfq_io_context {
  35         void *key;
  36         unsigned long dead_key;
  37
  38         struct cfq_queue *cfqq[2];
  39
  40         struct io_context *ioc;
  41
  42         unsigned long last_end_request;
  43
  44         unsigned long ttime_total;
  45         unsigned long ttime_samples;
  46         unsigned long ttime_mean;
  47
  48         struct list_head queue_list;
  49         struct hlist_node cic_list;
  50
  51         void (*dtor)(struct io_context *); /* destructor */
  52         void (*exit)(struct io_context *); /* called on task exit */
  53
  54         struct rcu_head rcu_head;
  55 };
  56
  57 /*
  58  * I/O subsystem state of the associated processes.  It is refcounted
  59  * and kmalloc'ed. These could be shared between processes.
  60  */
  61 struct io_context {
  62         atomic_long_t refcount;
  63         atomic_t nr_tasks;
  64
  65         /* all the fields below are protected by this lock */
  66         spinlock_t lock;
  67
  68         unsigned short ioprio;
  69         unsigned short ioprio_changed;
  70
  71 #ifdef CONFIG_BLK_CGROUP
  72         unsigned short cgroup_changed;
  73 #endif
  74
  75         /*
  76          * For request batching
  77          */
  78         unsigned long last_waited; /* Time last woken after wait for request */
  79         int nr_batch_requests;     /* Number of requests left in the batch */
  80
  81         struct as_io_context *aic;
  82         struct radix_tree_root radix_root;
  83         struct hlist_head cic_list;
  84         void *ioc_data;
  85 };
  86
  87 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  88 {
  89         /*
  90          * if ref count is zero, don't allow sharing (ioc is going away, it's
  91          * a race).
  92          */
  93         if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  94                 atomic_inc(&ioc->nr_tasks);
  95                 return ioc;
  96         }
  97
  98         return NULL;
  99 }
 100
 101 struct task_struct;
 102 #ifdef CONFIG_BLOCK
 103 int put_io_context(struct io_context *ioc);
 104 void exit_io_context(struct task_struct *task);
 105 struct io_context *get_io_context(gfp_t gfp_flags, int node);
 106 struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
 107 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 108 #else
 109 static inline void exit_io_context(struct task_struct *task)
 110 {
 111 }
 112
 113 struct io_context;
 114 static inline int put_io_context(struct io_context *ioc)
 115 {
 116         return 1;
 117 }
 118 #endif
 119
 120 #endif