include/linux/aio.h

   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
   8 #include <asm/atomic.h>
   9
  10 #define AIO_MAXSEGS             4
  11 #define AIO_KIOGRP_NR_ATOMIC    8
  12
  13 struct kioctx;
  14
  15 /* Notes on cancelling a kiocb:
  16  *      If a kiocb is cancelled, aio_complete may return 0 to indicate
  17  *      that cancel has not yet disposed of the kiocb.  All cancel
  18  *      operations *must* call aio_put_req to dispose of the kiocb
  19  *      to guard against races with the completion code.
  20  */
  21 #define KIOCB_C_CANCELLED       0x01
  22 #define KIOCB_C_COMPLETE        0x02
  23
  24 #define KIOCB_SYNC_KEY          (~0U)
  25
  26 /* ki_flags bits */
  27 /*
  28  * This may be used for cancel/retry serialization in the future, but
  29  * for now it's unused and we probably don't want modules to even
  30  * think they can use it.
  31  */
  32 /* #define KIF_LOCKED           0 */
  33 #define KIF_KICKED              1
  34 #define KIF_CANCELLED           2
  35
  36 #define kiocbTryLock(iocb)      test_and_set_bit(KIF_LOCKED, &(iocb)->ki_flags)
  37 #define kiocbTryKick(iocb)      test_and_set_bit(KIF_KICKED, &(iocb)->ki_flags)
  38
  39 #define kiocbSetLocked(iocb)    set_bit(KIF_LOCKED, &(iocb)->ki_flags)
  40 #define kiocbSetKicked(iocb)    set_bit(KIF_KICKED, &(iocb)->ki_flags)
  41 #define kiocbSetCancelled(iocb) set_bit(KIF_CANCELLED, &(iocb)->ki_flags)
  42
  43 #define kiocbClearLocked(iocb)  clear_bit(KIF_LOCKED, &(iocb)->ki_flags)
  44 #define kiocbClearKicked(iocb)  clear_bit(KIF_KICKED, &(iocb)->ki_flags)
  45 #define kiocbClearCancelled(iocb)       clear_bit(KIF_CANCELLED, &(iocb)->ki_flags)
  46
  47 #define kiocbIsLocked(iocb)     test_bit(KIF_LOCKED, &(iocb)->ki_flags)
  48 #define kiocbIsKicked(iocb)     test_bit(KIF_KICKED, &(iocb)->ki_flags)
  49 #define kiocbIsCancelled(iocb)  test_bit(KIF_CANCELLED, &(iocb)->ki_flags)
  50
  51 /* is there a better place to document function pointer methods? */
  52 /**
  53  * ki_retry     -       iocb forward progress callback
  54  * @kiocb:      The kiocb struct to advance by performing an operation.
  55  *
  56  * This callback is called when the AIO core wants a given AIO operation
  57  * to make forward progress.  The kiocb argument describes the operation
  58  * that is to be performed.  As the operation proceeds, perhaps partially,
  59  * ki_retry is expected to update the kiocb with progress made.  Typically
  60  * ki_retry is set in the AIO core and it itself calls file_operations
  61  * helpers.
  62  *
  63  * ki_retry's return value determines when the AIO operation is completed
  64  * and an event is generated in the AIO event ring.  Except the special
  65  * return values described below, the value that is returned from ki_retry
  66  * is transferred directly into the completion ring as the operation's
  67  * resulting status.  Once this has happened ki_retry *MUST NOT* reference
  68  * the kiocb pointer again.
  69  *
  70  * If ki_retry returns -EIOCBQUEUED it has made a promise that aio_complete()
  71  * will be called on the kiocb pointer in the future.  The AIO core will
  72  * not ask the method again -- ki_retry must ensure forward progress.
  73  * aio_complete() must be called once and only once in the future, multiple
  74  * calls may result in undefined behaviour.
  75  *
  76  * If ki_retry returns -EIOCBRETRY it has made a promise that kick_iocb()
  77  * will be called on the kiocb pointer in the future.  This may happen
  78  * through generic helpers that associate kiocb->ki_wait with a wait
  79  * queue head that ki_retry uses via current->io_wait.  It can also happen
  80  * with custom tracking and manual calls to kick_iocb(), though that is
  81  * discouraged.  In either case, kick_iocb() must be called once and only
  82  * once.  ki_retry must ensure forward progress, the AIO core will wait
  83  * indefinitely for kick_iocb() to be called.
  84  */
  85 struct kiocb {
  86         struct list_head        ki_run_list;
  87         long                    ki_flags;
  88         int                     ki_users;
  89         unsigned                ki_key;         /* id of this request */
  90
  91         struct file             *ki_filp;
  92         struct kioctx           *ki_ctx;        /* may be NULL for sync ops */
  93         int                     (*ki_cancel)(struct kiocb *, struct io_event *);
  94         ssize_t                 (*ki_retry)(struct kiocb *);
  95         void                    (*ki_dtor)(struct kiocb *);
  96
  97         struct list_head        ki_list;        /* the aio core uses this
  98                                                  * for cancellation */
  99
 100         union {
 101                 void __user             *user;
 102                 struct task_struct      *tsk;
 103         } ki_obj;
 104         __u64                   ki_user_data;   /* user's data for completion */
 105         loff_t                  ki_pos;
 106         /* State that we remember to be able to restart/retry  */
 107         unsigned short          ki_opcode;
 108         size_t                  ki_nbytes;      /* copy of iocb->aio_nbytes */
 109         char                    __user *ki_buf; /* remaining iocb->aio_buf */
 110         size_t                  ki_left;        /* remaining bytes */
 111         wait_queue_t            ki_wait;
 112         long                    ki_retried;     /* just for testing */
 113         long                    ki_kicked;      /* just for testing */
 114         long                    ki_queued;      /* just for testing */
 115
 116         void                    *private;
 117 };
 118
 119 #define is_sync_kiocb(iocb)     ((iocb)->ki_key == KIOCB_SYNC_KEY)
 120 #define init_sync_kiocb(x, filp)                        \
 121         do {                                            \
 122                 struct task_struct *tsk = current;      \
 123                 (x)->ki_flags = 0;                      \
 124                 (x)->ki_users = 1;                      \
 125                 (x)->ki_key = KIOCB_SYNC_KEY;           \
 126                 (x)->ki_filp = (filp);                  \
 127                 (x)->ki_ctx = NULL;                     \
 128                 (x)->ki_cancel = NULL;                  \
 129                 (x)->ki_dtor = NULL;                    \
 130                 (x)->ki_obj.tsk = tsk;                  \
 131                 (x)->ki_user_data = 0;                  \
 132                 init_wait((&(x)->ki_wait));             \
 133         } while (0)
 134
 135 #define AIO_RING_MAGIC                  0xa10a10a1
 136 #define AIO_RING_COMPAT_FEATURES        1
 137 #define AIO_RING_INCOMPAT_FEATURES      0
 138 struct aio_ring {
 139         unsigned        id;     /* kernel internal index number */
 140         unsigned        nr;     /* number of io_events */
 141         unsigned        head;
 142         unsigned        tail;
 143
 144         unsigned        magic;
 145         unsigned        compat_features;
 146         unsigned        incompat_features;
 147         unsigned        header_length;  /* size of aio_ring */
 148
 149
 150         struct io_event         io_events[0];
 151 }; /* 128 bytes + ring size */
 152
 153 #define aio_ring_avail(info, ring)      (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr)
 154
 155 #define AIO_RING_PAGES  8
 156 struct aio_ring_info {
 157         unsigned long           mmap_base;
 158         unsigned long           mmap_size;
 159
 160         struct page             **ring_pages;
 161         spinlock_t              ring_lock;
 162         long                    nr_pages;
 163
 164         unsigned                nr, tail;
 165
 166         struct page             *internal_pages[AIO_RING_PAGES];
 167 };
 168
 169 struct kioctx {
 170         atomic_t                users;
 171         int                     dead;
 172         struct mm_struct        *mm;
 173
 174         /* This needs improving */
 175         unsigned long           user_id;
 176         struct kioctx           *next;
 177
 178         wait_queue_head_t       wait;
 179
 180         spinlock_t              ctx_lock;
 181
 182         int                     reqs_active;
 183         struct list_head        active_reqs;    /* used for cancellation */
 184         struct list_head        run_list;       /* used for kicked reqs */
 185
 186         /* sys_io_setup currently limits this to an unsigned int */
 187         unsigned                max_reqs;
 188
 189         struct aio_ring_info    ring_info;
 190
 191         struct work_struct      wq;
 192 };
 193
 194 /* prototypes */
 195 extern unsigned aio_max_size;
 196
 197 extern ssize_t FASTCALL(wait_on_sync_kiocb(struct kiocb *iocb));
 198 extern int FASTCALL(aio_put_req(struct kiocb *iocb));
 199 extern void FASTCALL(kick_iocb(struct kiocb *iocb));
 200 extern int FASTCALL(aio_complete(struct kiocb *iocb, long res, long res2));
 201 extern void FASTCALL(__put_ioctx(struct kioctx *ctx));
 202 struct mm_struct;
 203 extern void FASTCALL(exit_aio(struct mm_struct *mm));
 204 extern struct kioctx *lookup_ioctx(unsigned long ctx_id);
 205 extern int FASTCALL(io_submit_one(struct kioctx *ctx,
 206                         struct iocb __user *user_iocb, struct iocb *iocb));
 207
 208 /* semi private, but used by the 32bit emulations: */
 209 struct kioctx *lookup_ioctx(unsigned long ctx_id);
 210 int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 211                                   struct iocb *iocb));
 212
 213 #define get_ioctx(kioctx) do {                                          \
 214         BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0));           \
 215         atomic_inc(&(kioctx)->users);                                   \
 216 } while (0)
 217 #define put_ioctx(kioctx) do {                                          \
 218         BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0));           \
 219         if (unlikely(atomic_dec_and_test(&(kioctx)->users)))            \
 220                 __put_ioctx(kioctx);                                    \
 221 } while (0)
 222
 223 #define in_aio() !is_sync_wait(current->io_wait)
 224 /* may be used for debugging */
 225 #define warn_if_async()                                                 \
 226 do {                                                                    \
 227         if (in_aio()) {                                                 \
 228                 printk(KERN_ERR "%s(%s:%d) called in async context!\n", \
 229                         __FUNCTION__, __FILE__, __LINE__);              \
 230                 dump_stack();                                           \
 231         }                                                               \
 232 } while (0)
 233
 234 #define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 235 #define is_retried_kiocb(iocb) ((iocb)->ki_retried > 1)
 236
 237 #include <linux/aio_abi.h>
 238
 239 static inline struct kiocb *list_kiocb(struct list_head *h)
 240 {
 241         return list_entry(h, struct kiocb, ki_list);
 242 }
 243
 244 /* for sysctl: */
 245 extern unsigned long aio_nr;
 246 extern unsigned long aio_max_nr;
 247
 248 #endif /* __LINUX__AIO_H */