238 lines
7.4 KiB
C
238 lines
7.4 KiB
C
#ifndef __LINUX__AIO_H
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#define __LINUX__AIO_H
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#include <linux/list.h>
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#include <linux/workqueue.h>
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#include <linux/aio_abi.h>
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#include <linux/uio.h>
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#include <linux/rcupdate.h>
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#include <asm/atomic.h>
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#define AIO_MAXSEGS 4
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#define AIO_KIOGRP_NR_ATOMIC 8
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struct kioctx;
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/* Notes on cancelling a kiocb:
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* If a kiocb is cancelled, aio_complete may return 0 to indicate
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* that cancel has not yet disposed of the kiocb. All cancel
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* operations *must* call aio_put_req to dispose of the kiocb
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* to guard against races with the completion code.
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*/
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#define KIOCB_C_CANCELLED 0x01
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#define KIOCB_C_COMPLETE 0x02
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#define KIOCB_SYNC_KEY (~0U)
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/* ki_flags bits */
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/*
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* This may be used for cancel/retry serialization in the future, but
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* for now it's unused and we probably don't want modules to even
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* think they can use it.
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*/
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/* #define KIF_LOCKED 0 */
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#define KIF_KICKED 1
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#define KIF_CANCELLED 2
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#define kiocbTryLock(iocb) test_and_set_bit(KIF_LOCKED, &(iocb)->ki_flags)
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#define kiocbTryKick(iocb) test_and_set_bit(KIF_KICKED, &(iocb)->ki_flags)
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#define kiocbSetLocked(iocb) set_bit(KIF_LOCKED, &(iocb)->ki_flags)
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#define kiocbSetKicked(iocb) set_bit(KIF_KICKED, &(iocb)->ki_flags)
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#define kiocbSetCancelled(iocb) set_bit(KIF_CANCELLED, &(iocb)->ki_flags)
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#define kiocbClearLocked(iocb) clear_bit(KIF_LOCKED, &(iocb)->ki_flags)
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#define kiocbClearKicked(iocb) clear_bit(KIF_KICKED, &(iocb)->ki_flags)
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#define kiocbClearCancelled(iocb) clear_bit(KIF_CANCELLED, &(iocb)->ki_flags)
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#define kiocbIsLocked(iocb) test_bit(KIF_LOCKED, &(iocb)->ki_flags)
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#define kiocbIsKicked(iocb) test_bit(KIF_KICKED, &(iocb)->ki_flags)
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#define kiocbIsCancelled(iocb) test_bit(KIF_CANCELLED, &(iocb)->ki_flags)
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/* is there a better place to document function pointer methods? */
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/**
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* ki_retry - iocb forward progress callback
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* @kiocb: The kiocb struct to advance by performing an operation.
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*
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* This callback is called when the AIO core wants a given AIO operation
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* to make forward progress. The kiocb argument describes the operation
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* that is to be performed. As the operation proceeds, perhaps partially,
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* ki_retry is expected to update the kiocb with progress made. Typically
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* ki_retry is set in the AIO core and it itself calls file_operations
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* helpers.
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*
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* ki_retry's return value determines when the AIO operation is completed
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* and an event is generated in the AIO event ring. Except the special
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* return values described below, the value that is returned from ki_retry
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* is transferred directly into the completion ring as the operation's
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* resulting status. Once this has happened ki_retry *MUST NOT* reference
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* the kiocb pointer again.
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*
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* If ki_retry returns -EIOCBQUEUED it has made a promise that aio_complete()
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* will be called on the kiocb pointer in the future. The AIO core will
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* not ask the method again -- ki_retry must ensure forward progress.
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* aio_complete() must be called once and only once in the future, multiple
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* calls may result in undefined behaviour.
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*
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* If ki_retry returns -EIOCBRETRY it has made a promise that kick_iocb()
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* will be called on the kiocb pointer in the future. This may happen
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* through generic helpers that associate kiocb->ki_wait with a wait
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* queue head that ki_retry uses via current->io_wait. It can also happen
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* with custom tracking and manual calls to kick_iocb(), though that is
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* discouraged. In either case, kick_iocb() must be called once and only
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* once. ki_retry must ensure forward progress, the AIO core will wait
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* indefinitely for kick_iocb() to be called.
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*/
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struct kiocb {
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struct list_head ki_run_list;
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unsigned long ki_flags;
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int ki_users;
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unsigned ki_key; /* id of this request */
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struct file *ki_filp;
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struct kioctx *ki_ctx; /* may be NULL for sync ops */
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int (*ki_cancel)(struct kiocb *, struct io_event *);
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ssize_t (*ki_retry)(struct kiocb *);
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void (*ki_dtor)(struct kiocb *);
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union {
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void __user *user;
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struct task_struct *tsk;
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} ki_obj;
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__u64 ki_user_data; /* user's data for completion */
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wait_queue_t ki_wait;
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loff_t ki_pos;
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void *private;
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/* State that we remember to be able to restart/retry */
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unsigned short ki_opcode;
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size_t ki_nbytes; /* copy of iocb->aio_nbytes */
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char __user *ki_buf; /* remaining iocb->aio_buf */
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size_t ki_left; /* remaining bytes */
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struct iovec ki_inline_vec; /* inline vector */
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struct iovec *ki_iovec;
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unsigned long ki_nr_segs;
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unsigned long ki_cur_seg;
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struct list_head ki_list; /* the aio core uses this
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* for cancellation */
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/*
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* If the aio_resfd field of the userspace iocb is not zero,
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* this is the underlying eventfd context to deliver events to.
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*/
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struct eventfd_ctx *ki_eventfd;
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};
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#define is_sync_kiocb(iocb) ((iocb)->ki_key == KIOCB_SYNC_KEY)
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#define init_sync_kiocb(x, filp) \
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do { \
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struct task_struct *tsk = current; \
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(x)->ki_flags = 0; \
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(x)->ki_users = 1; \
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(x)->ki_key = KIOCB_SYNC_KEY; \
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(x)->ki_filp = (filp); \
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(x)->ki_ctx = NULL; \
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(x)->ki_cancel = NULL; \
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(x)->ki_retry = NULL; \
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(x)->ki_dtor = NULL; \
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(x)->ki_obj.tsk = tsk; \
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(x)->ki_user_data = 0; \
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init_wait((&(x)->ki_wait)); \
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} while (0)
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#define AIO_RING_MAGIC 0xa10a10a1
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#define AIO_RING_COMPAT_FEATURES 1
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#define AIO_RING_INCOMPAT_FEATURES 0
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struct aio_ring {
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unsigned id; /* kernel internal index number */
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unsigned nr; /* number of io_events */
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unsigned head;
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unsigned tail;
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unsigned magic;
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unsigned compat_features;
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unsigned incompat_features;
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unsigned header_length; /* size of aio_ring */
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struct io_event io_events[0];
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}; /* 128 bytes + ring size */
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#define aio_ring_avail(info, ring) (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr)
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#define AIO_RING_PAGES 8
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struct aio_ring_info {
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unsigned long mmap_base;
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unsigned long mmap_size;
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struct page **ring_pages;
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spinlock_t ring_lock;
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long nr_pages;
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unsigned nr, tail;
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struct page *internal_pages[AIO_RING_PAGES];
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};
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struct kioctx {
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atomic_t users;
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int dead;
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struct mm_struct *mm;
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/* This needs improving */
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unsigned long user_id;
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struct hlist_node list;
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wait_queue_head_t wait;
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spinlock_t ctx_lock;
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int reqs_active;
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struct list_head active_reqs; /* used for cancellation */
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struct list_head run_list; /* used for kicked reqs */
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/* sys_io_setup currently limits this to an unsigned int */
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unsigned max_reqs;
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struct aio_ring_info ring_info;
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struct delayed_work wq;
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struct rcu_head rcu_head;
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};
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/* prototypes */
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extern unsigned aio_max_size;
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#ifdef CONFIG_AIO
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extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
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extern int aio_put_req(struct kiocb *iocb);
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extern void kick_iocb(struct kiocb *iocb);
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extern int aio_complete(struct kiocb *iocb, long res, long res2);
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struct mm_struct;
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extern void exit_aio(struct mm_struct *mm);
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#else
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static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
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static inline int aio_put_req(struct kiocb *iocb) { return 0; }
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static inline void kick_iocb(struct kiocb *iocb) { }
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static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
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struct mm_struct;
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static inline void exit_aio(struct mm_struct *mm) { }
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#endif /* CONFIG_AIO */
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#define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
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static inline struct kiocb *list_kiocb(struct list_head *h)
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{
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return list_entry(h, struct kiocb, ki_list);
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}
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/* for sysctl: */
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extern unsigned long aio_nr;
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extern unsigned long aio_max_nr;
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#endif /* __LINUX__AIO_H */
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