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Diffstat (limited to 'include/linux/aio.h')
| -rw-r--r-- | include/linux/aio.h | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/include/linux/aio.h b/include/linux/aio.h new file mode 100644 index 00000000..7a8db415 --- /dev/null +++ b/include/linux/aio.h @@ -0,0 +1,238 @@ +#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 <asm/atomic.h> + +#define AIO_MAXSEGS 4 +#define AIO_KIOGRP_NR_ATOMIC 8 + +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 KIF_CANCELLED 2 + +#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 */ + + /* + * 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; +}; + +#define is_sync_kiocb(iocb) ((iocb)->ki_key == KIOCB_SYNC_KEY) +#define init_sync_kiocb(x, filp) \ + do { \ + struct task_struct *tsk = current; \ + (x)->ki_flags = 0; \ + (x)->ki_users = 1; \ + (x)->ki_key = KIOCB_SYNC_KEY; \ + (x)->ki_filp = (filp); \ + (x)->ki_ctx = NULL; \ + (x)->ki_cancel = NULL; \ + (x)->ki_retry = NULL; \ + (x)->ki_dtor = NULL; \ + (x)->ki_obj.tsk = tsk; \ + (x)->ki_user_data = 0; \ + } while (0) + +#define AIO_RING_MAGIC 0xa10a10a1 +#define AIO_RING_COMPAT_FEATURES 1 +#define AIO_RING_INCOMPAT_FEATURES 0 +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_avail(info, ring) (((ring)->head + (info)->nr - 1 - (ring)->tail) % (info)->nr) + +#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]; +}; + +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; + +#ifdef CONFIG_AIO +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); +#else +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 */ |