include/linux/iocontext.h

   1 #ifndef IOCONTEXT_H
   2 #define IOCONTEXT_H
   3
   4 #include <linux/radix-tree.h>
   5
   6 /*
   7  * This is the per-process anticipatory I/O scheduler state.
   8  */
   9 struct as_io_context {
  10         spinlock_t lock;
  11
  12         void (*dtor)(struct as_io_context *aic); /* destructor */
  13         void (*exit)(struct as_io_context *aic); /* called on task exit */
  14
  15         unsigned long state;
  16         atomic_t nr_queued; /* queued reads & sync writes */
  17         atomic_t nr_dispatched; /* number of requests gone to the drivers */
  18
  19         /* IO History tracking */
  20         /* Thinktime */
  21         unsigned long last_end_request;
  22         unsigned long ttime_total;
  23         unsigned long ttime_samples;
  24         unsigned long ttime_mean;
  25         /* Layout pattern */
  26         unsigned int seek_samples;
  27         sector_t last_request_pos;
  28         u64 seek_total;
  29         sector_t seek_mean;
  30 };
  31
  32 struct cfq_queue;
  33 struct cfq_io_context {
  34         void *key;
  35         unsigned long dead_key;
  36
  37         struct cfq_queue *cfqq[2];
  38
  39         struct io_context *ioc;
  40
  41         unsigned long last_end_request;
  42         sector_t last_request_pos;
  43
  44         unsigned long ttime_total;
  45         unsigned long ttime_samples;
  46         unsigned long ttime_mean;
  47
  48         unsigned int seek_samples;
  49         u64 seek_total;
  50         sector_t seek_mean;
  51
  52         struct list_head queue_list;
  53
  54         void (*dtor)(struct io_context *); /* destructor */
  55         void (*exit)(struct io_context *); /* called on task exit */
  56 };
  57
  58 /*
  59  * I/O subsystem state of the associated processes.  It is refcounted
  60  * and kmalloc'ed. These could be shared between processes.
  61  */
  62 struct io_context {
  63         atomic_t refcount;
  64         atomic_t nr_tasks;
  65
  66         /* all the fields below are protected by this lock */
  67         spinlock_t lock;
  68
  69         unsigned short ioprio;
  70         unsigned short ioprio_changed;
  71
  72         /*
  73          * For request batching
  74          */
  75         unsigned long last_waited; /* Time last woken after wait for request */
  76         int nr_batch_requests;     /* Number of requests left in the batch */
  77
  78         struct as_io_context *aic;
  79         struct radix_tree_root radix_root;
  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_inc_not_zero(&ioc->refcount))
  90                 return ioc;
  91
  92         return NULL;
  93 }
  94
  95 #endif