include/linux/iocontext.h

   1 #ifndef IOCONTEXT_H
   2 #define IOCONTEXT_H
   3
   4 /*
   5  * This is the per-process anticipatory I/O scheduler state.
   6  */
   7 struct as_io_context {
   8         spinlock_t lock;
   9
  10         void (*dtor)(struct as_io_context *aic); /* destructor */
  11         void (*exit)(struct as_io_context *aic); /* called on task exit */
  12
  13         unsigned long state;
  14         atomic_t nr_queued; /* queued reads & sync writes */
  15         atomic_t nr_dispatched; /* number of requests gone to the drivers */
  16
  17         /* IO History tracking */
  18         /* Thinktime */
  19         unsigned long last_end_request;
  20         unsigned long ttime_total;
  21         unsigned long ttime_samples;
  22         unsigned long ttime_mean;
  23         /* Layout pattern */
  24         unsigned int seek_samples;
  25         sector_t last_request_pos;
  26         u64 seek_total;
  27         sector_t seek_mean;
  28 };
  29
  30 struct cfq_queue;
  31 struct cfq_io_context {
  32         struct rb_node rb_node;
  33         void *key;
  34
  35         struct cfq_queue *cfqq[2];
  36
  37         struct io_context *ioc;
  38
  39         unsigned long last_end_request;
  40         sector_t last_request_pos;
  41
  42         unsigned long ttime_total;
  43         unsigned long ttime_samples;
  44         unsigned long ttime_mean;
  45
  46         unsigned int seek_samples;
  47         u64 seek_total;
  48         sector_t seek_mean;
  49
  50         struct list_head queue_list;
  51
  52         void (*dtor)(struct io_context *); /* destructor */
  53         void (*exit)(struct io_context *); /* called on task exit */
  54 };
  55
  56 /*
  57  * I/O subsystem state of the associated processes.  It is refcounted
  58  * and kmalloc'ed. These could be shared between processes.
  59  */
  60 struct io_context {
  61         atomic_t refcount;
  62         atomic_t nr_tasks;
  63
  64         /* all the fields below are protected by this lock */
  65         spinlock_t lock;
  66
  67         unsigned short ioprio;
  68         unsigned short ioprio_changed;
  69
  70         /*
  71          * For request batching
  72          */
  73         unsigned long last_waited; /* Time last woken after wait for request */
  74         int nr_batch_requests;     /* Number of requests left in the batch */
  75
  76         struct as_io_context *aic;
  77         struct rb_root cic_root;
  78         void *ioc_data;
  79 };
  80
  81 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  82 {
  83         /*
  84          * if ref count is zero, don't allow sharing (ioc is going away, it's
  85          * a race).
  86          */
  87         if (ioc && atomic_inc_not_zero(&ioc->refcount))
  88                 return ioc;
  89
  90         return NULL;
  91 }
  92
  93 #endif