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#ifndef __LINUX__AIO_H
#define __LINUX__AIO_H
#include <linux/list.h>
#include <linux/workqueue.h>
#include <linux/aio_abi.h>
#include <linux/uio.h>
#include <linux/rcupdate.h>
#include <linux/atomic.h>
#define AIO_MAXSEGS 4
struct kioctx;
/* Notes on cancelling a kiocb:
* If a kiocb is cancelled, aio_complete may return 0 to indicate
* that cancel has not yet disposed of the kiocb. All cancel
* operations *must* call aio_put_req to dispose of the kiocb
* to guard against races with the completion code.
#define KIOCB_C_CANCELLED 0x01
#define KIOCB_C_COMPLETE 0x02
#define KIOCB_SYNC_KEY (~0U)
/* ki_flags bits */
* This may be used for cancel/retry serialization in the future, but
* for now it's unused and we probably don't want modules to even
* think they can use it.
/* #define KIF_LOCKED 0 */
#define KIF_KICKED 1
#define kiocbTryLock(iocb) test_and_set_bit(KIF_LOCKED, &(iocb)->ki_flags)
#define kiocbTryKick(iocb) test_and_set_bit(KIF_KICKED, &(iocb)->ki_flags)
#define kiocbSetLocked(iocb) set_bit(KIF_LOCKED, &(iocb)->ki_flags)
#define kiocbSetKicked(iocb) set_bit(KIF_KICKED, &(iocb)->ki_flags)
#define kiocbSetCancelled(iocb) set_bit(KIF_CANCELLED, &(iocb)->ki_flags)
#define kiocbClearLocked(iocb) clear_bit(KIF_LOCKED, &(iocb)->ki_flags)
#define kiocbClearKicked(iocb) clear_bit(KIF_KICKED, &(iocb)->ki_flags)
#define kiocbClearCancelled(iocb) clear_bit(KIF_CANCELLED, &(iocb)->ki_flags)
#define kiocbIsLocked(iocb) test_bit(KIF_LOCKED, &(iocb)->ki_flags)
#define kiocbIsKicked(iocb) test_bit(KIF_KICKED, &(iocb)->ki_flags)
#define kiocbIsCancelled(iocb) test_bit(KIF_CANCELLED, &(iocb)->ki_flags)
/* is there a better place to document function pointer methods? */
* ki_retry - iocb forward progress callback
* @kiocb: The kiocb struct to advance by performing an operation.
* This callback is called when the AIO core wants a given AIO operation
* to make forward progress. The kiocb argument describes the operation
* that is to be performed. As the operation proceeds, perhaps partially,
* ki_retry is expected to update the kiocb with progress made. Typically
* ki_retry is set in the AIO core and it itself calls file_operations
* helpers.
* ki_retry's return value determines when the AIO operation is completed
* and an event is generated in the AIO event ring. Except the special
* return values described below, the value that is returned from ki_retry
* is transferred directly into the completion ring as the operation's
* resulting status. Once this has happened ki_retry *MUST NOT* reference
* the kiocb pointer again.
* If ki_retry returns -EIOCBQUEUED it has made a promise that aio_complete()
* will be called on the kiocb pointer in the future. The AIO core will
* not ask the method again -- ki_retry must ensure forward progress.
* aio_complete() must be called once and only once in the future, multiple
* calls may result in undefined behaviour.
* If ki_retry returns -EIOCBRETRY it has made a promise that kick_iocb()
* will be called on the kiocb pointer in the future. This may happen
* through generic helpers that associate kiocb->ki_wait with a wait
* queue head that ki_retry uses via current->io_wait. It can also happen
* with custom tracking and manual calls to kick_iocb(), though that is
* discouraged. In either case, kick_iocb() must be called once and only
* once. ki_retry must ensure forward progress, the AIO core will wait
* indefinitely for kick_iocb() to be called.
struct kiocb {
struct list_head ki_run_list;
unsigned long ki_flags;
int ki_users;
unsigned ki_key; /* id of this request */
struct file *ki_filp;
struct kioctx *ki_ctx; /* may be NULL for sync ops */
int (*ki_cancel)(struct kiocb *, struct io_event *);
ssize_t (*ki_retry)(struct kiocb *);
void (*ki_dtor)(struct kiocb *);
union {
void __user *user;
struct task_struct *tsk;
} ki_obj;
__u64 ki_user_data; /* user's data for completion */
loff_t ki_pos;
void *private;
/* State that we remember to be able to restart/retry */
unsigned short ki_opcode;
size_t ki_nbytes; /* copy of iocb->aio_nbytes */
char __user *ki_buf; /* remaining iocb->aio_buf */
size_t ki_left; /* remaining bytes */
struct iovec ki_inline_vec; /* inline vector */
struct iovec *ki_iovec;
unsigned long ki_nr_segs;
unsigned long ki_cur_seg;
struct list_head ki_list; /* the aio core uses this
* for cancellation */
struct list_head ki_batch; /* batch allocation */
* If the aio_resfd field of the userspace iocb is not zero,
* this is the underlying eventfd context to deliver events to.
struct eventfd_ctx *ki_eventfd;
static inline bool is_sync_kiocb(struct kiocb *kiocb)
return kiocb->ki_key == KIOCB_SYNC_KEY;
static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
*kiocb = (struct kiocb) {
.ki_users = 1,
.ki_key = KIOCB_SYNC_KEY,
.ki_filp = filp,
.ki_obj.tsk = current,
#define AIO_RING_MAGIC 0xa10a10a1
struct aio_ring {
unsigned id; /* kernel internal index number */
unsigned nr; /* number of io_events */
unsigned head;
unsigned tail;
unsigned magic;
unsigned compat_features;
unsigned incompat_features;
unsigned header_length; /* size of aio_ring */
struct io_event io_events[0];
}; /* 128 bytes + ring size */
#define AIO_RING_PAGES 8
struct aio_ring_info {
unsigned long mmap_base;
unsigned long mmap_size;
struct page **ring_pages;
spinlock_t ring_lock;
long nr_pages;
unsigned nr, tail;
struct page *internal_pages[AIO_RING_PAGES];
static inline unsigned aio_ring_avail(struct aio_ring_info *info,
struct aio_ring *ring)
return (ring->head + info->nr - 1 - ring->tail) % info->nr;
struct kioctx {
atomic_t users;
int dead;
struct mm_struct *mm;
/* This needs improving */
unsigned long user_id;
struct hlist_node list;
wait_queue_head_t wait;
spinlock_t ctx_lock;
int reqs_active;
struct list_head active_reqs; /* used for cancellation */
struct list_head run_list; /* used for kicked reqs */
/* sys_io_setup currently limits this to an unsigned int */
unsigned max_reqs;
struct aio_ring_info ring_info;
struct delayed_work wq;
struct rcu_head rcu_head;
/* prototypes */
extern unsigned aio_max_size;
extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
extern int aio_put_req(struct kiocb *iocb);
extern void kick_iocb(struct kiocb *iocb);
extern int aio_complete(struct kiocb *iocb, long res, long res2);
struct mm_struct;
extern void exit_aio(struct mm_struct *mm);
extern long do_io_submit(aio_context_t ctx_id, long nr,
struct iocb __user *__user *iocbpp, bool compat);
static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
static inline int aio_put_req(struct kiocb *iocb) { return 0; }
static inline void kick_iocb(struct kiocb *iocb) { }
static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
struct mm_struct;
static inline void exit_aio(struct mm_struct *mm) { }
static inline long do_io_submit(aio_context_t ctx_id, long nr,
struct iocb __user * __user *iocbpp,
bool compat) { return 0; }
#endif /* CONFIG_AIO */
static inline struct kiocb *list_kiocb(struct list_head *h)
return list_entry(h, struct kiocb, ki_list);
/* for sysctl: */
extern unsigned long aio_nr;
extern unsigned long aio_max_nr;
#endif /* __LINUX__AIO_H */