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-rw-r--r--include/linux/aio.h240
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diff --git a/include/linux/aio.h b/include/linux/aio.h
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+++ b/include/linux/aio.h
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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
+#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 */
+ 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;
+};
+
+#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; \
+ (x)->private = NULL; \
+ } 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 */