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