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 #include <linux/uio.h>
   8
   9 #include <asm/atomic.h>
  10
  11 #define AIO_MAXSEGS             4
  12 #define AIO_KIOGRP_NR_ATOMIC    8
  13
  14 struct kioctx;
  15
  16 /* Notes on cancelling a kiocb:
  17  *      If a kiocb is cancelled, aio_complete may return 0 to indicate
  18  *      that cancel has not yet disposed of the kiocb.  All cancel
  19  *      operations *must* call aio_put_req to dispose of the kiocb
  20  *      to guard against races with the completion code.
  21  */
  22 #define KIOCB_C_CANCELLED       0x01
  23 #define KIOCB_C_COMPLETE        0x02
  24
  25 #define KIOCB_SYNC_KEY          (~0U)
  26
  27 /* ki_flags bits */
  28 /*
  29  * This may be used for cancel/retry serialization in the future, but
  30  * for now it's unused and we probably don't want modules to even
  31  * think they can use it.
  32  */
  33 /* #define KIF_LOCKED           0 */
  34 #define KIF_KICKED              1
  35 #define KIF_CANCELLED           2
  36
  37 #define kiocbTryLock(iocb)      test_and_set_bit(KIF_LOCKED, &(iocb)->ki_flags)
  38 #define kiocbTryKick(iocb)      test_and_set_bit(KIF_KICKED, &(iocb)->ki_flags)
  39
  40 #define kiocbSetLocked(iocb)    set_bit(KIF_LOCKED, &(iocb)->ki_flags)
  41 #define kiocbSetKicked(iocb)    set_bit(KIF_KICKED, &(iocb)->ki_flags)
  42 #define kiocbSetCancelled(iocb) set_bit(KIF_CANCELLED, &(iocb)->ki_flags)
  43
  44 #define kiocbClearLocked(iocb)  clear_bit(KIF_LOCKED, &(iocb)->ki_flags)
  45 #define kiocbClearKicked(iocb)  clear_bit(KIF_KICKED, &(iocb)->ki_flags)
  46 #define kiocbClearCancelled(iocb)       clear_bit(KIF_CANCELLED, &(iocb)->ki_flags)
  47
  48 #define kiocbIsLocked(iocb)     test_bit(KIF_LOCKED, &(iocb)->ki_flags)
  49 #define kiocbIsKicked(iocb)     test_bit(KIF_KICKED, &(iocb)->ki_flags)
  50 #define kiocbIsCancelled(iocb)  test_bit(KIF_CANCELLED, &(iocb)->ki_flags)
  51
  52 /* is there a better place to document function pointer methods? */
  53 /**
  54  * ki_retry     -       iocb forward progress callback
  55  * @kiocb:      The kiocb struct to advance by performing an operation.
  56  *
  57  * This callback is called when the AIO core wants a given AIO operation
  58  * to make forward progress.  The kiocb argument describes the operation
  59  * that is to be performed.  As the operation proceeds, perhaps partially,
  60  * ki_retry is expected to update the kiocb with progress made.  Typically
  61  * ki_retry is set in the AIO core and it itself calls file_operations
  62  * helpers.
  63  *
  64  * ki_retry's return value determines when the AIO operation is completed
  65  * and an event is generated in the AIO event ring.  Except the special
  66  * return values described below, the value that is returned from ki_retry
  67  * is transferred directly into the completion ring as the operation's
  68  * resulting status.  Once this has happened ki_retry *MUST NOT* reference
  69  * the kiocb pointer again.
  70  *
  71  * If ki_retry returns -EIOCBQUEUED it has made a promise that aio_complete()
  72  * will be called on the kiocb pointer in the future.  The AIO core will
  73  * not ask the method again -- ki_retry must ensure forward progress.
  74  * aio_complete() must be called once and only once in the future, multiple
  75  * calls may result in undefined behaviour.
  76  *
  77  * If ki_retry returns -EIOCBRETRY it has made a promise that kick_iocb()
  78  * will be called on the kiocb pointer in the future.  This may happen
  79  * through generic helpers that associate kiocb->ki_wait with a wait
  80  * queue head that ki_retry uses via current->io_wait.  It can also happen
  81  * with custom tracking and manual calls to kick_iocb(), though that is
  82  * discouraged.  In either case, kick_iocb() must be called once and only
  83  * once.  ki_retry must ensure forward progress, the AIO core will wait
  84  * indefinitely for kick_iocb() to be called.
  85  */
  86 struct kiocb {
  87         struct list_head        ki_run_list;
  88         long                    ki_flags;
  89         int                     ki_users;
  90         unsigned                ki_key;         /* id of this request */
  91
  92         struct file             *ki_filp;
  93         struct kioctx           *ki_ctx;        /* may be NULL for sync ops */
  94         int                     (*ki_cancel)(struct kiocb *, struct io_event *);
  95         ssize_t                 (*ki_retry)(struct kiocb *);
  96         void                    (*ki_dtor)(struct kiocb *);
  97
  98         union {
  99                 void __user             *user;
 100                 struct task_struct      *tsk;
 101         } ki_obj;
 102
 103         __u64                   ki_user_data;   /* user's data for completion */
 104         wait_queue_t            ki_wait;
 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         long                    ki_retried;     /* just for testing */
 114         long                    ki_kicked;      /* just for testing */
 115         long                    ki_queued;      /* just for testing */
 116         struct iovec            ki_inline_vec;  /* inline vector */
 117
 118         struct list_head        ki_list;        /* the aio core uses this
 119                                                  * for cancellation */
 120 };
 121
 122 #define is_sync_kiocb(iocb)     ((iocb)->ki_key == KIOCB_SYNC_KEY)
 123 #define init_sync_kiocb(x, filp)                        \
 124         do {                                            \
 125                 struct task_struct *tsk = current;      \
 126                 (x)->ki_flags = 0;                      \
 127                 (x)->ki_users = 1;                      \
 128                 (x)->ki_key = KIOCB_SYNC_KEY;           \
 129                 (x)->ki_filp = (filp);                  \
 130                 (x)->ki_ctx = NULL;                     \
 131                 (x)->ki_cancel = NULL;                  \
 132                 (x)->ki_retry = NULL;                   \
 133                 (x)->ki_dtor = NULL;                    \
 134                 (x)->ki_obj.tsk = tsk;                  \
 135                 (x)->ki_user_data = 0;                  \
 136                 init_wait((&(x)->ki_wait));             \
 137         } while (0)
 138
 139 #define AIO_RING_MAGIC                  0xa10a10a1
 140 #define AIO_RING_COMPAT_FEATURES        1
 141 #define AIO_RING_INCOMPAT_FEATURES      0
 142 struct aio_ring {
 143         unsigned        id;     /* kernel internal index number */
 144         unsigned        nr;     /* number of io_events */
 145         unsigned        head;
 146         unsigned        tail;
 147
 148         unsigned        magic;
 149         unsigned        compat_features;
 150         unsigned        incompat_features;
 151         unsigned        header_length;  /* size of aio_ring */
 152
 153
 154         struct io_event         io_events[0];
 155 }; /* 128 bytes + ring size */
 156
 157 #define aio_ring_avail(info, ring)      (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr)
 158
 159 #define AIO_RING_PAGES  8
 160 struct aio_ring_info {
 161         unsigned long           mmap_base;
 162         unsigned long           mmap_size;
 163
 164         struct page             **ring_pages;
 165         spinlock_t              ring_lock;
 166         long                    nr_pages;
 167
 168         unsigned                nr, tail;
 169
 170         struct page             *internal_pages[AIO_RING_PAGES];
 171 };
 172
 173 struct kioctx {
 174         atomic_t                users;
 175         int                     dead;
 176         struct mm_struct        *mm;
 177
 178         /* This needs improving */
 179         unsigned long           user_id;
 180         struct kioctx           *next;
 181
 182         wait_queue_head_t       wait;
 183
 184         spinlock_t              ctx_lock;
 185
 186         int                     reqs_active;
 187         struct list_head        active_reqs;    /* used for cancellation */
 188         struct list_head        run_list;       /* used for kicked reqs */
 189
 190         /* sys_io_setup currently limits this to an unsigned int */
 191         unsigned                max_reqs;
 192
 193         struct aio_ring_info    ring_info;
 194
 195         struct work_struct      wq;
 196 };
 197
 198 /* prototypes */
 199 extern unsigned aio_max_size;
 200
 201 extern ssize_t FASTCALL(wait_on_sync_kiocb(struct kiocb *iocb));
 202 extern int FASTCALL(aio_put_req(struct kiocb *iocb));
 203 extern void FASTCALL(kick_iocb(struct kiocb *iocb));
 204 extern int FASTCALL(aio_complete(struct kiocb *iocb, long res, long res2));
 205 extern void FASTCALL(__put_ioctx(struct kioctx *ctx));
 206 struct mm_struct;
 207 extern void FASTCALL(exit_aio(struct mm_struct *mm));
 208 extern struct kioctx *lookup_ioctx(unsigned long ctx_id);
 209 extern int FASTCALL(io_submit_one(struct kioctx *ctx,
 210                         struct iocb __user *user_iocb, struct iocb *iocb));
 211
 212 /* semi private, but used by the 32bit emulations: */
 213 struct kioctx *lookup_ioctx(unsigned long ctx_id);
 214 int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 215                                   struct iocb *iocb));
 216
 217 #define get_ioctx(kioctx) do {                                          \
 218         BUG_ON(atomic_read(&(kioctx)->users) <= 0);                     \
 219         atomic_inc(&(kioctx)->users);                                   \
 220 } while (0)
 221 #define put_ioctx(kioctx) do {                                          \
 222         BUG_ON(atomic_read(&(kioctx)->users) <= 0);                     \
 223         if (unlikely(atomic_dec_and_test(&(kioctx)->users)))            \
 224                 __put_ioctx(kioctx);                                    \
 225 } while (0)
 226
 227 #define in_aio() !is_sync_wait(current->io_wait)
 228 /* may be used for debugging */
 229 #define warn_if_async()                                                 \
 230 do {                                                                    \
 231         if (in_aio()) {                                                 \
 232                 printk(KERN_ERR "%s(%s:%d) called in async context!\n", \
 233                         __FUNCTION__, __FILE__, __LINE__);              \
 234                 dump_stack();                                           \
 235         }                                                               \
 236 } while (0)
 237
 238 #define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 239 #define is_retried_kiocb(iocb) ((iocb)->ki_retried > 1)
 240
 241 #include <linux/aio_abi.h>
 242
 243 static inline struct kiocb *list_kiocb(struct list_head *h)
 244 {
 245         return list_entry(h, struct kiocb, ki_list);
 246 }
 247
 248 /* for sysctl: */
 249 extern unsigned long aio_nr;
 250 extern unsigned long aio_max_nr;
 251
 252 #endif /* __LINUX__AIO_H */