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         /*
  72          * For request batching
  73          */
  74         unsigned long last_waited; /* Time last woken after wait for request */
  75         int nr_batch_requests;     /* Number of requests left in the batch */
  76
  77         struct as_io_context *aic;
  78         struct radix_tree_root radix_root;
  79         struct hlist_head cic_list;
  80         void *ioc_data;
  81 };
  82
  83 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  84 {
  85         /*
  86          * if ref count is zero, don't allow sharing (ioc is going away, it's
  87          * a race).
  88          */
  89         if (ioc && atomic_long_inc_not_zero(&ioc->refcount)) {
  90                 atomic_inc(&ioc->nr_tasks);
  91                 return ioc;
  92         }
  93
  94         return NULL;
  95 }
  96
  97 #ifdef CONFIG_BLOCK
  98 int put_io_context(struct io_context *ioc);
  99 void exit_io_context(void);
 100 struct io_context *get_io_context(gfp_t gfp_flags, int node);
 101 struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
 102 void copy_io_context(struct io_context **pdst, struct io_context **psrc);
 103 #else
 104 static inline void exit_io_context(void)
 105 {
 106 }
 107
 108 struct io_context;
 109 static inline int put_io_context(struct io_context *ioc)
 110 {
 111         return 1;
 112 }
 113 #endif
 114
 115 #endif