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1 : #ifndef __LINUX__AIO_H
2 : #define __LINUX__AIO_H
3 :
4 : #include <linux/list.h>
5 : #include <linux/workqueue.h>
6 : #include <linux/aio_abi.h>
7 : #include <linux/uio.h>
8 : #include <linux/rcupdate.h>
9 :
10 : #include <asm/atomic.h>
11 :
12 : #define AIO_MAXSEGS 4
13 : #define AIO_KIOGRP_NR_ATOMIC 8
14 :
15 : struct kioctx;
16 :
17 : /* Notes on cancelling a kiocb:
18 : * If a kiocb is cancelled, aio_complete may return 0 to indicate
19 : * that cancel has not yet disposed of the kiocb. All cancel
20 : * operations *must* call aio_put_req to dispose of the kiocb
21 : * to guard against races with the completion code.
22 : */
23 : #define KIOCB_C_CANCELLED 0x01
24 : #define KIOCB_C_COMPLETE 0x02
25 :
26 : #define KIOCB_SYNC_KEY (~0U)
27 :
28 : /* ki_flags bits */
29 : /*
30 : * This may be used for cancel/retry serialization in the future, but
31 : * for now it's unused and we probably don't want modules to even
32 : * think they can use it.
33 : */
34 : /* #define KIF_LOCKED 0 */
35 : #define KIF_KICKED 1
36 : #define KIF_CANCELLED 2
37 :
38 : #define kiocbTryLock(iocb) test_and_set_bit(KIF_LOCKED, &(iocb)->ki_flags)
39 : #define kiocbTryKick(iocb) test_and_set_bit(KIF_KICKED, &(iocb)->ki_flags)
40 :
41 : #define kiocbSetLocked(iocb) set_bit(KIF_LOCKED, &(iocb)->ki_flags)
42 : #define kiocbSetKicked(iocb) set_bit(KIF_KICKED, &(iocb)->ki_flags)
43 : #define kiocbSetCancelled(iocb) set_bit(KIF_CANCELLED, &(iocb)->ki_flags)
44 :
45 : #define kiocbClearLocked(iocb) clear_bit(KIF_LOCKED, &(iocb)->ki_flags)
46 : #define kiocbClearKicked(iocb) clear_bit(KIF_KICKED, &(iocb)->ki_flags)
47 : #define kiocbClearCancelled(iocb) clear_bit(KIF_CANCELLED, &(iocb)->ki_flags)
48 :
49 : #define kiocbIsLocked(iocb) test_bit(KIF_LOCKED, &(iocb)->ki_flags)
50 : #define kiocbIsKicked(iocb) test_bit(KIF_KICKED, &(iocb)->ki_flags)
51 : #define kiocbIsCancelled(iocb) test_bit(KIF_CANCELLED, &(iocb)->ki_flags)
52 :
53 : /* is there a better place to document function pointer methods? */
54 : /**
55 : * ki_retry - iocb forward progress callback
56 : * @kiocb: The kiocb struct to advance by performing an operation.
57 : *
58 : * This callback is called when the AIO core wants a given AIO operation
59 : * to make forward progress. The kiocb argument describes the operation
60 : * that is to be performed. As the operation proceeds, perhaps partially,
61 : * ki_retry is expected to update the kiocb with progress made. Typically
62 : * ki_retry is set in the AIO core and it itself calls file_operations
63 : * helpers.
64 : *
65 : * ki_retry's return value determines when the AIO operation is completed
66 : * and an event is generated in the AIO event ring. Except the special
67 : * return values described below, the value that is returned from ki_retry
68 : * is transferred directly into the completion ring as the operation's
69 : * resulting status. Once this has happened ki_retry *MUST NOT* reference
70 : * the kiocb pointer again.
71 : *
72 : * If ki_retry returns -EIOCBQUEUED it has made a promise that aio_complete()
73 : * will be called on the kiocb pointer in the future. The AIO core will
74 : * not ask the method again -- ki_retry must ensure forward progress.
75 : * aio_complete() must be called once and only once in the future, multiple
76 : * calls may result in undefined behaviour.
77 : *
78 : * If ki_retry returns -EIOCBRETRY it has made a promise that kick_iocb()
79 : * will be called on the kiocb pointer in the future. This may happen
80 : * through generic helpers that associate kiocb->ki_wait with a wait
81 : * queue head that ki_retry uses via current->io_wait. It can also happen
82 : * with custom tracking and manual calls to kick_iocb(), though that is
83 : * discouraged. In either case, kick_iocb() must be called once and only
84 : * once. ki_retry must ensure forward progress, the AIO core will wait
85 : * indefinitely for kick_iocb() to be called.
86 : */
87 : struct kiocb {
88 : struct list_head ki_run_list;
89 : unsigned long ki_flags;
90 : int ki_users;
91 : unsigned ki_key; /* id of this request */
92 :
93 : struct file *ki_filp;
94 : struct kioctx *ki_ctx; /* may be NULL for sync ops */
95 : int (*ki_cancel)(struct kiocb *, struct io_event *);
96 : ssize_t (*ki_retry)(struct kiocb *);
97 : void (*ki_dtor)(struct kiocb *);
98 :
99 : union {
100 : void __user *user;
101 : struct task_struct *tsk;
102 : } ki_obj;
103 :
104 : __u64 ki_user_data; /* user's data for completion */
105 : loff_t ki_pos;
106 :
107 : void *private;
108 : /* State that we remember to be able to restart/retry */
109 : unsigned short ki_opcode;
110 : size_t ki_nbytes; /* copy of iocb->aio_nbytes */
111 : char __user *ki_buf; /* remaining iocb->aio_buf */
112 : size_t ki_left; /* remaining bytes */
113 : struct iovec ki_inline_vec; /* inline vector */
114 : struct iovec *ki_iovec;
115 : unsigned long ki_nr_segs;
116 : unsigned long ki_cur_seg;
117 :
118 : struct list_head ki_list; /* the aio core uses this
119 : * for cancellation */
120 :
121 : /*
122 : * If the aio_resfd field of the userspace iocb is not zero,
123 : * this is the underlying eventfd context to deliver events to.
124 : */
125 : struct eventfd_ctx *ki_eventfd;
126 : };
127 :
128 : #define is_sync_kiocb(iocb) ((iocb)->ki_key == KIOCB_SYNC_KEY)
129 : #define init_sync_kiocb(x, filp) \
130 : do { \
131 : struct task_struct *tsk = current; \
132 : (x)->ki_flags = 0; \
133 : (x)->ki_users = 1; \
134 : (x)->ki_key = KIOCB_SYNC_KEY; \
135 : (x)->ki_filp = (filp); \
136 : (x)->ki_ctx = NULL; \
137 : (x)->ki_cancel = NULL; \
138 : (x)->ki_retry = NULL; \
139 : (x)->ki_dtor = NULL; \
140 : (x)->ki_obj.tsk = tsk; \
141 : (x)->ki_user_data = 0; \
142 : } while (0)
143 :
144 : #define AIO_RING_MAGIC 0xa10a10a1
145 : #define AIO_RING_COMPAT_FEATURES 1
146 : #define AIO_RING_INCOMPAT_FEATURES 0
147 : struct aio_ring {
148 : unsigned id; /* kernel internal index number */
149 : unsigned nr; /* number of io_events */
150 : unsigned head;
151 : unsigned tail;
152 :
153 : unsigned magic;
154 : unsigned compat_features;
155 : unsigned incompat_features;
156 : unsigned header_length; /* size of aio_ring */
157 :
158 :
159 : struct io_event io_events[0];
160 : }; /* 128 bytes + ring size */
161 1 :
162 : #define aio_ring_avail(info, ring) (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr)
163 :
164 : #define AIO_RING_PAGES 8
165 : struct aio_ring_info {
166 : unsigned long mmap_base;
167 : unsigned long mmap_size;
168 :
169 : struct page **ring_pages;
170 : spinlock_t ring_lock;
171 : long nr_pages;
172 :
173 : unsigned nr, tail;
174 :
175 : struct page *internal_pages[AIO_RING_PAGES];
176 : };
177 1 :
178 : struct kioctx {
179 : atomic_t users;
180 : int dead;
181 : struct mm_struct *mm;
182 :
183 : /* This needs improving */
184 : unsigned long user_id;
185 : struct hlist_node list;
186 :
187 : wait_queue_head_t wait;
188 :
189 : spinlock_t ctx_lock;
190 :
191 : int reqs_active;
192 : struct list_head active_reqs; /* used for cancellation */
193 : struct list_head run_list; /* used for kicked reqs */
194 :
195 : /* sys_io_setup currently limits this to an unsigned int */
196 : unsigned max_reqs;
197 :
198 : struct aio_ring_info ring_info;
199 :
200 : struct delayed_work wq;
201 :
202 : struct rcu_head rcu_head;
203 : };
204 :
205 : /* prototypes */
206 : extern unsigned aio_max_size;
207 :
208 : #ifdef CONFIG_AIO
209 : extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
210 : extern int aio_put_req(struct kiocb *iocb);
211 : extern void kick_iocb(struct kiocb *iocb);
212 : extern int aio_complete(struct kiocb *iocb, long res, long res2);
213 : struct mm_struct;
214 : extern void exit_aio(struct mm_struct *mm);
215 : #else
216 : static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
217 : static inline int aio_put_req(struct kiocb *iocb) { return 0; }
218 : static inline void kick_iocb(struct kiocb *iocb) { }
219 : static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
220 : struct mm_struct;
221 : static inline void exit_aio(struct mm_struct *mm) { }
222 : #endif /* CONFIG_AIO */
223 :
224 : static inline struct kiocb *list_kiocb(struct list_head *h)
225 : {
226 : return list_entry(h, struct kiocb, ki_list);
227 : }
228 :
229 : /* for sysctl: */
230 : extern unsigned long aio_nr;
231 : extern unsigned long aio_max_nr;
232 :
233 : #endif /* __LINUX__AIO_H */
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