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         union {
  98                 void __user             *user;
  99                 struct task_struct      *tsk;
 100         } ki_obj;
 101
 102         __u64                   ki_user_data;   /* user's data for completion */
 103         wait_queue_t            ki_wait;
 104         loff_t                  ki_pos;
 105
 106         void                    *private;
 107         /* State that we remember to be able to restart/retry  */
 108         unsigned short          ki_opcode;
 109         size_t                  ki_nbytes;      /* copy of iocb->aio_nbytes */
 110         char                    __user *ki_buf; /* remaining iocb->aio_buf */
 111         size_t                  ki_left;        /* remaining bytes */
 112         long                    ki_retried;     /* just for testing */
 113         long                    ki_kicked;      /* just for testing */
 114         long                    ki_queued;      /* just for testing */
 115
 116         struct list_head        ki_list;        /* the aio core uses this
 117                                                  * for cancellation */
 118 };
 119
 120 #define is_sync_kiocb(iocb)     ((iocb)->ki_key == KIOCB_SYNC_KEY)
 121 #define init_sync_kiocb(x, filp)                        \
 122         do {                                            \
 123                 struct task_struct *tsk = current;      \
 124                 (x)->ki_flags = 0;                      \
 125                 (x)->ki_users = 1;                      \
 126                 (x)->ki_key = KIOCB_SYNC_KEY;           \
 127                 (x)->ki_filp = (filp);                  \
 128                 (x)->ki_ctx = NULL;                     \
 129                 (x)->ki_cancel = NULL;                  \
 130                 (x)->ki_retry = NULL;                   \
 131                 (x)->ki_dtor = NULL;                    \
 132                 (x)->ki_obj.tsk = tsk;                  \
 133                 (x)->ki_user_data = 0;                  \
 134                 init_wait((&(x)->ki_wait));             \
 135         } while (0)
 136
 137 #define AIO_RING_MAGIC                  0xa10a10a1
 138 #define AIO_RING_COMPAT_FEATURES        1
 139 #define AIO_RING_INCOMPAT_FEATURES      0
 140 struct aio_ring {
 141         unsigned        id;     /* kernel internal index number */
 142         unsigned        nr;     /* number of io_events */
 143         unsigned        head;
 144         unsigned        tail;
 145
 146         unsigned        magic;
 147         unsigned        compat_features;
 148         unsigned        incompat_features;
 149         unsigned        header_length;  /* size of aio_ring */
 150
 151
 152         struct io_event         io_events[0];
 153 }; /* 128 bytes + ring size */
 154
 155 #define aio_ring_avail(info, ring)      (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr)
 156
 157 #define AIO_RING_PAGES  8
 158 struct aio_ring_info {
 159         unsigned long           mmap_base;
 160         unsigned long           mmap_size;
 161
 162         struct page             **ring_pages;
 163         spinlock_t              ring_lock;
 164         long                    nr_pages;
 165
 166         unsigned                nr, tail;
 167
 168         struct page             *internal_pages[AIO_RING_PAGES];
 169 };
 170
 171 struct kioctx {
 172         atomic_t                users;
 173         int                     dead;
 174         struct mm_struct        *mm;
 175
 176         /* This needs improving */
 177         unsigned long           user_id;
 178         struct kioctx           *next;
 179
 180         wait_queue_head_t       wait;
 181
 182         spinlock_t              ctx_lock;
 183
 184         int                     reqs_active;
 185         struct list_head        active_reqs;    /* used for cancellation */
 186         struct list_head        run_list;       /* used for kicked reqs */
 187
 188         /* sys_io_setup currently limits this to an unsigned int */
 189         unsigned                max_reqs;
 190
 191         struct aio_ring_info    ring_info;
 192
 193         struct work_struct      wq;
 194 };
 195
 196 /* prototypes */
 197 extern unsigned aio_max_size;
 198
 199 extern ssize_t FASTCALL(wait_on_sync_kiocb(struct kiocb *iocb));
 200 extern int FASTCALL(aio_put_req(struct kiocb *iocb));
 201 extern void FASTCALL(kick_iocb(struct kiocb *iocb));
 202 extern int FASTCALL(aio_complete(struct kiocb *iocb, long res, long res2));
 203 extern void FASTCALL(__put_ioctx(struct kioctx *ctx));
 204 struct mm_struct;
 205 extern void FASTCALL(exit_aio(struct mm_struct *mm));
 206 extern struct kioctx *lookup_ioctx(unsigned long ctx_id);
 207 extern int FASTCALL(io_submit_one(struct kioctx *ctx,
 208                         struct iocb __user *user_iocb, struct iocb *iocb));
 209
 210 /* semi private, but used by the 32bit emulations: */
 211 struct kioctx *lookup_ioctx(unsigned long ctx_id);
 212 int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 213                                   struct iocb *iocb));
 214
 215 #define get_ioctx(kioctx) do {                                          \
 216         BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0));           \
 217         atomic_inc(&(kioctx)->users);                                   \
 218 } while (0)
 219 #define put_ioctx(kioctx) do {                                          \
 220         BUG_ON(unlikely(atomic_read(&(kioctx)->users) <= 0));           \
 221         if (unlikely(atomic_dec_and_test(&(kioctx)->users)))            \
 222                 __put_ioctx(kioctx);                                    \
 223 } while (0)
 224
 225 #define in_aio() !is_sync_wait(current->io_wait)
 226 /* may be used for debugging */
 227 #define warn_if_async()                                                 \
 228 do {                                                                    \
 229         if (in_aio()) {                                                 \
 230                 printk(KERN_ERR "%s(%s:%d) called in async context!\n", \
 231                         __FUNCTION__, __FILE__, __LINE__);              \
 232                 dump_stack();                                           \
 233         }                                                               \
 234 } while (0)
 235
 236 #define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 237 #define is_retried_kiocb(iocb) ((iocb)->ki_retried > 1)
 238
 239 #include <linux/aio_abi.h>
 240
 241 static inline struct kiocb *list_kiocb(struct list_head *h)
 242 {
 243         return list_entry(h, struct kiocb, ki_list);
 244 }
 245
 246 /* for sysctl: */
 247 extern unsigned long aio_nr;
 248 extern unsigned long aio_max_nr;
 249
 250 #endif /* __LINUX__AIO_H */