1
2
3
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/init.h>
7#include <linux/bio.h>
8#include <linux/blkdev.h>
9#include <linux/bootmem.h>
10
11#include "blk.h"
12
13
14
15
16static struct kmem_cache *iocontext_cachep;
17
18static void cfq_dtor(struct io_context *ioc)
19{
20 if (!hlist_empty(&ioc->cic_list)) {
21 struct cfq_io_context *cic;
22
23 cic = list_entry(ioc->cic_list.first, struct cfq_io_context,
24 cic_list);
25 cic->dtor(ioc);
26 }
27}
28
29
30
31
32
33int put_io_context(struct io_context *ioc)
34{
35 if (ioc == NULL)
36 return 1;
37
38 BUG_ON(atomic_read(&ioc->refcount) == 0);
39
40 if (atomic_dec_and_test(&ioc->refcount)) {
41 rcu_read_lock();
42 if (ioc->aic && ioc->aic->dtor)
43 ioc->aic->dtor(ioc->aic);
44 cfq_dtor(ioc);
45 rcu_read_unlock();
46
47 kmem_cache_free(iocontext_cachep, ioc);
48 return 1;
49 }
50 return 0;
51}
52EXPORT_SYMBOL(put_io_context);
53
54static void cfq_exit(struct io_context *ioc)
55{
56 rcu_read_lock();
57
58 if (!hlist_empty(&ioc->cic_list)) {
59 struct cfq_io_context *cic;
60
61 cic = list_entry(ioc->cic_list.first, struct cfq_io_context,
62 cic_list);
63 cic->exit(ioc);
64 }
65 rcu_read_unlock();
66}
67
68
69void exit_io_context(void)
70{
71 struct io_context *ioc;
72
73 task_lock(current);
74 ioc = current->io_context;
75 current->io_context = NULL;
76 task_unlock(current);
77
78 if (atomic_dec_and_test(&ioc->nr_tasks)) {
79 if (ioc->aic && ioc->aic->exit)
80 ioc->aic->exit(ioc->aic);
81 cfq_exit(ioc);
82
83 put_io_context(ioc);
84 }
85}
86
87struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
88{
89 struct io_context *ret;
90
91 ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
92 if (ret) {
93 atomic_set(&ret->refcount, 1);
94 atomic_set(&ret->nr_tasks, 1);
95 spin_lock_init(&ret->lock);
96 ret->ioprio_changed = 0;
97 ret->ioprio = 0;
98 ret->last_waited = jiffies;
99 ret->nr_batch_requests = 0;
100 ret->aic = NULL;
101 INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH);
102 INIT_HLIST_HEAD(&ret->cic_list);
103 ret->ioc_data = NULL;
104 }
105
106 return ret;
107}
108
109
110
111
112
113
114
115
116
117struct io_context *current_io_context(gfp_t gfp_flags, int node)
118{
119 struct task_struct *tsk = current;
120 struct io_context *ret;
121
122 ret = tsk->io_context;
123 if (likely(ret))
124 return ret;
125
126 ret = alloc_io_context(gfp_flags, node);
127 if (ret) {
128
129 smp_wmb();
130 tsk->io_context = ret;
131 }
132
133 return ret;
134}
135
136
137
138
139
140
141
142struct io_context *get_io_context(gfp_t gfp_flags, int node)
143{
144 struct io_context *ret = NULL;
145
146
147
148
149
150 do {
151 ret = current_io_context(gfp_flags, node);
152 if (unlikely(!ret))
153 break;
154 } while (!atomic_inc_not_zero(&ret->refcount));
155
156 return ret;
157}
158EXPORT_SYMBOL(get_io_context);
159
160void copy_io_context(struct io_context **pdst, struct io_context **psrc)
161{
162 struct io_context *src = *psrc;
163 struct io_context *dst = *pdst;
164
165 if (src) {
166 BUG_ON(atomic_read(&src->refcount) == 0);
167 atomic_inc(&src->refcount);
168 put_io_context(dst);
169 *pdst = src;
170 }
171}
172EXPORT_SYMBOL(copy_io_context);
173
174static int __init blk_ioc_init(void)
175{
176 iocontext_cachep = kmem_cache_create("blkdev_ioc",
177 sizeof(struct io_context), 0, SLAB_PANIC, NULL);
178 return 0;
179}
180subsys_initcall(blk_ioc_init);
181