LXR linux/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#include <linux/uio.h>
  11
  12#define AIO_MAXSEGS             4
  13#define AIO_KIOGRP_NR_ATOMIC    8
  14
  15struct 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 */
  87struct kiocb {
  88        struct list_head        ki_run_list;
  89        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        wait_queue_t            ki_wait;
 106        loff_t                  ki_pos;
 107
 108        atomic_t                ki_bio_count;   /* num bio used for this iocb */
 109        void                    *private;
 110        /* State that we remember to be able to restart/retry  */
 111        unsigned short          ki_opcode;
 112        size_t                  ki_nbytes;      /* copy of iocb->aio_nbytes */
 113        char                    __user *ki_buf; /* remaining iocb->aio_buf */
 114        size_t                  ki_left;        /* remaining bytes */
 115        struct iovec            ki_inline_vec;  /* inline vector */
 116        struct iovec            *ki_iovec;
 117        unsigned long           ki_nr_segs;
 118        unsigned long           ki_cur_seg;
 119
 120        struct list_head        ki_list;        /* the aio core uses this
 121                                                 * for cancellation */
 122
 123        /*
 124         * If the aio_resfd field of the userspace iocb is not zero,
 125         * this is the underlying file* to deliver event to.
 126         */
 127        struct file             *ki_eventfd;
 128};
 129
 130#define is_sync_kiocb(iocb)     ((iocb)->ki_key == KIOCB_SYNC_KEY)
 131#define init_sync_kiocb(x, filp)                        \
 132        do {                                            \
 133                struct task_struct *tsk = current;      \
 134                (x)->ki_flags = 0;                      \
 135                (x)->ki_users = 1;                      \
 136                (x)->ki_key = KIOCB_SYNC_KEY;           \
 137                (x)->ki_filp = (filp);                  \
 138                (x)->ki_ctx = NULL;                     \
 139                (x)->ki_cancel = NULL;                  \
 140                (x)->ki_retry = NULL;                   \
 141                (x)->ki_dtor = NULL;                    \
 142                (x)->ki_obj.tsk = tsk;                  \
 143                (x)->ki_user_data = 0;                  \
 144                init_wait((&(x)->ki_wait));             \
 145        } while (0)
 146
 147#define AIO_RING_MAGIC                  0xa10a10a1
 148#define AIO_RING_COMPAT_FEATURES        1
 149#define AIO_RING_INCOMPAT_FEATURES      0
 150struct aio_ring {
 151        unsigned        id;     /* kernel internal index number */
 152        unsigned        nr;     /* number of io_events */
 153        unsigned        head;
 154        unsigned        tail;
 155
 156        unsigned        magic;
 157        unsigned        compat_features;
 158        unsigned        incompat_features;
 159        unsigned        header_length;  /* size of aio_ring */
 160
 161
 162        struct io_event         io_events[0];
 163}; /* 128 bytes + ring size */
 164
 165#define aio_ring_avail(info, ring)      (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr)
 166
 167#define AIO_RING_PAGES  8
 168struct aio_ring_info {
 169        unsigned long           mmap_base;
 170        unsigned long           mmap_size;
 171
 172        struct page             **ring_pages;
 173        spinlock_t              ring_lock;
 174        long                    nr_pages;
 175
 176        unsigned                nr, tail;
 177
 178        struct page             *internal_pages[AIO_RING_PAGES];
 179};
 180
 181struct kioctx {
 182        atomic_t                users;
 183        int                     dead;
 184        struct mm_struct        *mm;
 185
 186        /* This needs improving */
 187        unsigned long           user_id;
 188        struct kioctx           *next;
 189
 190        wait_queue_head_t       wait;
 191
 192        spinlock_t              ctx_lock;
 193
 194        int                     reqs_active;
 195        struct list_head        active_reqs;    /* used for cancellation */
 196        struct list_head        run_list;       /* used for kicked reqs */
 197
 198        /* sys_io_setup currently limits this to an unsigned int */
 199        unsigned                max_reqs;
 200
 201        struct aio_ring_info    ring_info;
 202
 203        struct delayed_work     wq;
 204};
 205
 206/* prototypes */
 207extern unsigned aio_max_size;
 208
 209extern ssize_t FASTCALL(wait_on_sync_kiocb(struct kiocb *iocb));
 210extern int FASTCALL(aio_put_req(struct kiocb *iocb));
 211extern void FASTCALL(kick_iocb(struct kiocb *iocb));
 212extern int FASTCALL(aio_complete(struct kiocb *iocb, long res, long res2));
 213extern void FASTCALL(__put_ioctx(struct kioctx *ctx));
 214struct mm_struct;
 215extern void FASTCALL(exit_aio(struct mm_struct *mm));
 216extern struct kioctx *lookup_ioctx(unsigned long ctx_id);
 217extern int FASTCALL(io_submit_one(struct kioctx *ctx,
 218                        struct iocb __user *user_iocb, struct iocb *iocb));
 219
 220/* semi private, but used by the 32bit emulations: */
 221struct kioctx *lookup_ioctx(unsigned long ctx_id);
 222int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 223                                  struct iocb *iocb));
 224
 225#define get_ioctx(kioctx) do {                                          \
 226        BUG_ON(atomic_read(&(kioctx)->users) <= 0);                     \
 227        atomic_inc(&(kioctx)->users);                                   \
 228} while (0)
 229#define put_ioctx(kioctx) do {                                          \
 230        BUG_ON(atomic_read(&(kioctx)->users) <= 0);                     \
 231        if (unlikely(atomic_dec_and_test(&(kioctx)->users)))            \
 232                __put_ioctx(kioctx);                                    \
 233} while (0)
 234
 235#define in_aio() (unlikely(!is_sync_wait(current->io_wait)))
 236
 237/* may be used for debugging */
 238#define warn_if_async()                                                 \
 239do {                                                                    \
 240        if (in_aio()) {                                                 \
 241                printk(KERN_ERR "%s(%s:%d) called in async context!\n", \
 242                        __FUNCTION__, __FILE__, __LINE__);              \
 243                dump_stack();                                           \
 244        }                                                               \
 245} while (0)
 246
 247#define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 248
 249#include <linux/aio_abi.h>
 250
 251static inline struct kiocb *list_kiocb(struct list_head *h)
 252{
 253        return list_entry(h, struct kiocb, ki_list);
 254}
 255
 256/* for sysctl: */
 257extern unsigned long aio_nr;
 258extern unsigned long aio_max_nr;
 259
 260#endif /* __LINUX__AIO_H */
 261