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
  11#define AIO_MAXSEGS             4
  12#define AIO_KIOGRP_NR_ATOMIC    8
  13
  14struct 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 */
  86struct kiocb {
  87        struct list_head        ki_run_list;
  88        unsigned 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        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 file* to deliver event to.
 124         */
 125        struct file             *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                init_wait((&(x)->ki_wait));             \
 143        } while (0)
 144
 145#define AIO_RING_MAGIC                  0xa10a10a1
 146#define AIO_RING_COMPAT_FEATURES        1
 147#define AIO_RING_INCOMPAT_FEATURES      0
 148struct aio_ring {
 149        unsigned        id;     /* kernel internal index number */
 150        unsigned        nr;     /* number of io_events */
 151        unsigned        head;
 152        unsigned        tail;
 153
 154        unsigned        magic;
 155        unsigned        compat_features;
 156        unsigned        incompat_features;
 157        unsigned        header_length;  /* size of aio_ring */
 158
 159
 160        struct io_event         io_events[0];
 161}; /* 128 bytes + ring size */
 162
 163#define aio_ring_avail(info, ring)      (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr)
 164
 165#define AIO_RING_PAGES  8
 166struct aio_ring_info {
 167        unsigned long           mmap_base;
 168        unsigned long           mmap_size;
 169
 170        struct page             **ring_pages;
 171        spinlock_t              ring_lock;
 172        long                    nr_pages;
 173
 174        unsigned                nr, tail;
 175
 176        struct page             *internal_pages[AIO_RING_PAGES];
 177};
 178
 179struct kioctx {
 180        atomic_t                users;
 181        int                     dead;
 182        struct mm_struct        *mm;
 183
 184        /* This needs improving */
 185        unsigned long           user_id;
 186        struct kioctx           *next;
 187
 188        wait_queue_head_t       wait;
 189
 190        spinlock_t              ctx_lock;
 191
 192        int                     reqs_active;
 193        struct list_head        active_reqs;    /* used for cancellation */
 194        struct list_head        run_list;       /* used for kicked reqs */
 195
 196        /* sys_io_setup currently limits this to an unsigned int */
 197        unsigned                max_reqs;
 198
 199        struct aio_ring_info    ring_info;
 200
 201        struct delayed_work     wq;
 202};
 203
 204/* prototypes */
 205extern unsigned aio_max_size;
 206
 207#ifdef CONFIG_AIO
 208extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
 209extern int aio_put_req(struct kiocb *iocb);
 210extern void kick_iocb(struct kiocb *iocb);
 211extern int aio_complete(struct kiocb *iocb, long res, long res2);
 212struct mm_struct;
 213extern void exit_aio(struct mm_struct *mm);
 214#else
 215static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
 216static inline int aio_put_req(struct kiocb *iocb) { return 0; }
 217static inline void kick_iocb(struct kiocb *iocb) { }
 218static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
 219struct mm_struct;
 220static inline void exit_aio(struct mm_struct *mm) { }
 221#endif /* CONFIG_AIO */
 222
 223#define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 224
 225#include <linux/aio_abi.h>
 226
 227static inline struct kiocb *list_kiocb(struct list_head *h)
 228{
 229        return list_entry(h, struct kiocb, ki_list);
 230}
 231
 232/* for sysctl: */
 233extern unsigned long aio_nr;
 234extern unsigned long aio_max_nr;
 235
 236#endif /* __LINUX__AIO_H */
 237