Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1729 insertions, 0 deletions

diff --git a/fs/aio.c b/fs/aio.c
new file mode 100644
index 00000000000..d06a266769b
--- /dev/null
+++ b/fs/aio.c
@@ -0,0 +1,1729 @@
+/*
+ *	An async IO implementation for Linux
+ *	Written by Benjamin LaHaise <bcrl@kvack.org>
+ *
+ *	Implements an efficient asynchronous io interface.
+ *
+ *	Copyright 2000, 2001, 2002 Red Hat, Inc.  All Rights Reserved.
+ *
+ *	See ../COPYING for licensing terms.
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/time.h>
+#include <linux/aio_abi.h>
+#include <linux/module.h>
+#include <linux/syscalls.h>
+
+#define DEBUG 0
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <linux/aio.h>
+#include <linux/highmem.h>
+#include <linux/workqueue.h>
+#include <linux/security.h>
+
+#include <asm/kmap_types.h>
+#include <asm/uaccess.h>
+#include <asm/mmu_context.h>
+
+#if DEBUG > 1
+#define dprintk		printk
+#else
+#define dprintk(x...)	do { ; } while (0)
+#endif
+
+long aio_run = 0; /* for testing only */
+long aio_wakeups = 0; /* for testing only */
+
+/*------ sysctl variables----*/
+atomic_t aio_nr = ATOMIC_INIT(0);	/* current system wide number of aio requests */
+unsigned aio_max_nr = 0x10000;	/* system wide maximum number of aio requests */
+/*----end sysctl variables---*/
+
+static kmem_cache_t	*kiocb_cachep;
+static kmem_cache_t	*kioctx_cachep;
+
+static struct workqueue_struct *aio_wq;
+
+/* Used for rare fput completion. */
+static void aio_fput_routine(void *);
+static DECLARE_WORK(fput_work, aio_fput_routine, NULL);
+
+static DEFINE_SPINLOCK(fput_lock);
+LIST_HEAD(fput_head);
+
+static void aio_kick_handler(void *);
+
+/* aio_setup
+ *	Creates the slab caches used by the aio routines, panic on
+ *	failure as this is done early during the boot sequence.
+ */
+static int __init aio_setup(void)
+{
+	kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb),
+				0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+	kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx),
+				0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
+
+	aio_wq = create_workqueue("aio");
+
+	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
+
+	return 0;
+}
+
+static void aio_free_ring(struct kioctx *ctx)
+{
+	struct aio_ring_info *info = &ctx->ring_info;
+	long i;
+
+	for (i=0; i<info->nr_pages; i++)
+		put_page(info->ring_pages[i]);
+
+	if (info->mmap_size) {
+		down_write(&ctx->mm->mmap_sem);
+		do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
+		up_write(&ctx->mm->mmap_sem);
+	}
+
+	if (info->ring_pages && info->ring_pages != info->internal_pages)
+		kfree(info->ring_pages);
+	info->ring_pages = NULL;
+	info->nr = 0;
+}
+
+static int aio_setup_ring(struct kioctx *ctx)
+{
+	struct aio_ring *ring;
+	struct aio_ring_info *info = &ctx->ring_info;
+	unsigned nr_events = ctx->max_reqs;
+	unsigned long size;
+	int nr_pages;
+
+	/* Compensate for the ring buffer's head/tail overlap entry */
+	nr_events += 2;	/* 1 is required, 2 for good luck */
+
+	size = sizeof(struct aio_ring);
+	size += sizeof(struct io_event) * nr_events;
+	nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
+
+	if (nr_pages < 0)
+		return -EINVAL;
+
+	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
+
+	info->nr = 0;
+	info->ring_pages = info->internal_pages;
+	if (nr_pages > AIO_RING_PAGES) {
+		info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL);
+		if (!info->ring_pages)
+			return -ENOMEM;
+		memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages);
+	}
+
+	info->mmap_size = nr_pages * PAGE_SIZE;
+	dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
+	down_write(&ctx->mm->mmap_sem);
+	info->mmap_base = do_mmap(NULL, 0, info->mmap_size, 
+				  PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE,
+				  0);
+	if (IS_ERR((void *)info->mmap_base)) {
+		up_write(&ctx->mm->mmap_sem);
+		printk("mmap err: %ld\n", -info->mmap_base);
+		info->mmap_size = 0;
+		aio_free_ring(ctx);
+		return -EAGAIN;
+	}
+
+	dprintk("mmap address: 0x%08lx\n", info->mmap_base);
+	info->nr_pages = get_user_pages(current, ctx->mm,
+					info->mmap_base, nr_pages, 
+					1, 0, info->ring_pages, NULL);
+	up_write(&ctx->mm->mmap_sem);
+
+	if (unlikely(info->nr_pages != nr_pages)) {
+		aio_free_ring(ctx);
+		return -EAGAIN;
+	}
+
+	ctx->user_id = info->mmap_base;
+
+	info->nr = nr_events;		/* trusted copy */
+
+	ring = kmap_atomic(info->ring_pages[0], KM_USER0);
+	ring->nr = nr_events;	/* user copy */
+	ring->id = ctx->user_id;
+	ring->head = ring->tail = 0;
+	ring->magic = AIO_RING_MAGIC;
+	ring->compat_features = AIO_RING_COMPAT_FEATURES;
+	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
+	ring->header_length = sizeof(struct aio_ring);
+	kunmap_atomic(ring, KM_USER0);
+
+	return 0;
+}
+
+
+/* aio_ring_event: returns a pointer to the event at the given index from
+ * kmap_atomic(, km).  Release the pointer with put_aio_ring_event();
+ */
+#define AIO_EVENTS_PER_PAGE	(PAGE_SIZE / sizeof(struct io_event))
+#define AIO_EVENTS_FIRST_PAGE	((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
+#define AIO_EVENTS_OFFSET	(AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
+
+#define aio_ring_event(info, nr, km) ({					\
+	unsigned pos = (nr) + AIO_EVENTS_OFFSET;			\
+	struct io_event *__event;					\
+	__event = kmap_atomic(						\
+			(info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
+	__event += pos % AIO_EVENTS_PER_PAGE;				\
+	__event;							\
+})
+
+#define put_aio_ring_event(event, km) do {	\
+	struct io_event *__event = (event);	\
+	(void)__event;				\
+	kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
+} while(0)
+
+/* ioctx_alloc
+ *	Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
+ */
+static struct kioctx *ioctx_alloc(unsigned nr_events)
+{
+	struct mm_struct *mm;
+	struct kioctx *ctx;
+
+	/* Prevent overflows */
+	if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
+	    (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
+		pr_debug("ENOMEM: nr_events too high\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (nr_events > aio_max_nr)
+		return ERR_PTR(-EAGAIN);
+
+	ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	memset(ctx, 0, sizeof(*ctx));
+	ctx->max_reqs = nr_events;
+	mm = ctx->mm = current->mm;
+	atomic_inc(&mm->mm_count);
+
+	atomic_set(&ctx->users, 1);
+	spin_lock_init(&ctx->ctx_lock);
+	spin_lock_init(&ctx->ring_info.ring_lock);
+	init_waitqueue_head(&ctx->wait);
+
+	INIT_LIST_HEAD(&ctx->active_reqs);
+	INIT_LIST_HEAD(&ctx->run_list);
+	INIT_WORK(&ctx->wq, aio_kick_handler, ctx);
+
+	if (aio_setup_ring(ctx) < 0)
+		goto out_freectx;
+
+	/* limit the number of system wide aios */
+	atomic_add(ctx->max_reqs, &aio_nr);	/* undone by __put_ioctx */
+	if (unlikely(atomic_read(&aio_nr) > aio_max_nr))
+		goto out_cleanup;
+
+	/* now link into global list.  kludge.  FIXME */
+	write_lock(&mm->ioctx_list_lock);
+	ctx->next = mm->ioctx_list;
+	mm->ioctx_list = ctx;
+	write_unlock(&mm->ioctx_list_lock);
+
+	dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
+		ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
+	return ctx;
+
+out_cleanup:
+	atomic_sub(ctx->max_reqs, &aio_nr);
+	ctx->max_reqs = 0;	/* prevent __put_ioctx from sub'ing aio_nr */
+	__put_ioctx(ctx);
+	return ERR_PTR(-EAGAIN);
+
+out_freectx:
+	mmdrop(mm);
+	kmem_cache_free(kioctx_cachep, ctx);
+	ctx = ERR_PTR(-ENOMEM);
+
+	dprintk("aio: error allocating ioctx %p\n", ctx);
+	return ctx;
+}
+
+/* aio_cancel_all
+ *	Cancels all outstanding aio requests on an aio context.  Used 
+ *	when the processes owning a context have all exited to encourage 
+ *	the rapid destruction of the kioctx.
+ */
+static void aio_cancel_all(struct kioctx *ctx)
+{
+	int (*cancel)(struct kiocb *, struct io_event *);
+	struct io_event res;
+	spin_lock_irq(&ctx->ctx_lock);
+	ctx->dead = 1;
+	while (!list_empty(&ctx->active_reqs)) {
+		struct list_head *pos = ctx->active_reqs.next;
+		struct kiocb *iocb = list_kiocb(pos);
+		list_del_init(&iocb->ki_list);
+		cancel = iocb->ki_cancel;
+		kiocbSetCancelled(iocb);
+		if (cancel) {
+			iocb->ki_users++;
+			spin_unlock_irq(&ctx->ctx_lock);
+			cancel(iocb, &res);
+			spin_lock_irq(&ctx->ctx_lock);
+		}
+	}
+	spin_unlock_irq(&ctx->ctx_lock);
+}
+
+void wait_for_all_aios(struct kioctx *ctx)
+{
+	struct task_struct *tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
+
+	if (!ctx->reqs_active)
+		return;
+
+	add_wait_queue(&ctx->wait, &wait);
+	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+	while (ctx->reqs_active) {
+		schedule();
+		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+	}
+	__set_task_state(tsk, TASK_RUNNING);
+	remove_wait_queue(&ctx->wait, &wait);
+}
+
+/* wait_on_sync_kiocb:
+ *	Waits on the given sync kiocb to complete.
+ */
+ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb)
+{
+	while (iocb->ki_users) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (!iocb->ki_users)
+			break;
+		schedule();
+	}
+	__set_current_state(TASK_RUNNING);
+	return iocb->ki_user_data;
+}
+
+/* exit_aio: called when the last user of mm goes away.  At this point, 
+ * there is no way for any new requests to be submited or any of the 
+ * io_* syscalls to be called on the context.  However, there may be 
+ * outstanding requests which hold references to the context; as they 
+ * go away, they will call put_ioctx and release any pinned memory
+ * associated with the request (held via struct page * references).
+ */
+void fastcall exit_aio(struct mm_struct *mm)
+{
+	struct kioctx *ctx = mm->ioctx_list;
+	mm->ioctx_list = NULL;
+	while (ctx) {
+		struct kioctx *next = ctx->next;
+		ctx->next = NULL;
+		aio_cancel_all(ctx);
+
+		wait_for_all_aios(ctx);
+		/*
+		 * this is an overkill, but ensures we don't leave
+		 * the ctx on the aio_wq
+		 */
+		flush_workqueue(aio_wq);
+
+		if (1 != atomic_read(&ctx->users))
+			printk(KERN_DEBUG
+				"exit_aio:ioctx still alive: %d %d %d\n",
+				atomic_read(&ctx->users), ctx->dead,
+				ctx->reqs_active);
+		put_ioctx(ctx);
+		ctx = next;
+	}
+}
+
+/* __put_ioctx
+ *	Called when the last user of an aio context has gone away,
+ *	and the struct needs to be freed.
+ */
+void fastcall __put_ioctx(struct kioctx *ctx)
+{
+	unsigned nr_events = ctx->max_reqs;
+
+	if (unlikely(ctx->reqs_active))
+		BUG();
+
+	cancel_delayed_work(&ctx->wq);
+	flush_workqueue(aio_wq);
+	aio_free_ring(ctx);
+	mmdrop(ctx->mm);
+	ctx->mm = NULL;
+	pr_debug("__put_ioctx: freeing %p\n", ctx);
+	kmem_cache_free(kioctx_cachep, ctx);
+
+	atomic_sub(nr_events, &aio_nr);
+}
+
+/* aio_get_req
+ *	Allocate a slot for an aio request.  Increments the users count
+ * of the kioctx so that the kioctx stays around until all requests are
+ * complete.  Returns NULL if no requests are free.
+ *
+ * Returns with kiocb->users set to 2.  The io submit code path holds
+ * an extra reference while submitting the i/o.
+ * This prevents races between the aio code path referencing the
+ * req (after submitting it) and aio_complete() freeing the req.
+ */
+static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx));
+static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx)
+{
+	struct kiocb *req = NULL;
+	struct aio_ring *ring;
+	int okay = 0;
+
+	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
+	if (unlikely(!req))
+		return NULL;
+
+	req->ki_flags = 1 << KIF_LOCKED;
+	req->ki_users = 2;
+	req->ki_key = 0;
+	req->ki_ctx = ctx;
+	req->ki_cancel = NULL;
+	req->ki_retry = NULL;
+	req->ki_obj.user = NULL;
+	req->ki_dtor = NULL;
+	req->private = NULL;
+	INIT_LIST_HEAD(&req->ki_run_list);
+
+	/* Check if the completion queue has enough free space to
+	 * accept an event from this io.
+	 */
+	spin_lock_irq(&ctx->ctx_lock);
+	ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
+	if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
+		list_add(&req->ki_list, &ctx->active_reqs);
+		get_ioctx(ctx);
+		ctx->reqs_active++;
+		okay = 1;
+	}
+	kunmap_atomic(ring, KM_USER0);
+	spin_unlock_irq(&ctx->ctx_lock);
+
+	if (!okay) {
+		kmem_cache_free(kiocb_cachep, req);
+		req = NULL;
+	}
+
+	return req;
+}
+
+static inline struct kiocb *aio_get_req(struct kioctx *ctx)
+{
+	struct kiocb *req;
+	/* Handle a potential starvation case -- should be exceedingly rare as 
+	 * requests will be stuck on fput_head only if the aio_fput_routine is 
+	 * delayed and the requests were the last user of the struct file.
+	 */
+	req = __aio_get_req(ctx);
+	if (unlikely(NULL == req)) {
+		aio_fput_routine(NULL);
+		req = __aio_get_req(ctx);
+	}
+	return req;
+}
+
+static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
+{
+	if (req->ki_dtor)
+		req->ki_dtor(req);
+	req->ki_ctx = NULL;
+	req->ki_filp = NULL;
+	req->ki_obj.user = NULL;
+	req->ki_dtor = NULL;
+	req->private = NULL;
+	kmem_cache_free(kiocb_cachep, req);
+	ctx->reqs_active--;
+
+	if (unlikely(!ctx->reqs_active && ctx->dead))
+		wake_up(&ctx->wait);
+}
+
+static void aio_fput_routine(void *data)
+{
+	spin_lock_irq(&fput_lock);
+	while (likely(!list_empty(&fput_head))) {
+		struct kiocb *req = list_kiocb(fput_head.next);
+		struct kioctx *ctx = req->ki_ctx;
+
+		list_del(&req->ki_list);
+		spin_unlock_irq(&fput_lock);
+
+		/* Complete the fput */
+		__fput(req->ki_filp);
+
+		/* Link the iocb into the context's free list */
+		spin_lock_irq(&ctx->ctx_lock);
+		really_put_req(ctx, req);
+		spin_unlock_irq(&ctx->ctx_lock);
+
+		put_ioctx(ctx);
+		spin_lock_irq(&fput_lock);
+	}
+	spin_unlock_irq(&fput_lock);
+}
+
+/* __aio_put_req
+ *	Returns true if this put was the last user of the request.
+ */
+static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
+{
+	dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n",
+		req, atomic_read(&req->ki_filp->f_count));
+
+	req->ki_users --;
+	if (unlikely(req->ki_users < 0))
+		BUG();
+	if (likely(req->ki_users))
+		return 0;
+	list_del(&req->ki_list);		/* remove from active_reqs */
+	req->ki_cancel = NULL;
+	req->ki_retry = NULL;
+
+	/* Must be done under the lock to serialise against cancellation.
+	 * Call this aio_fput as it duplicates fput via the fput_work.
+	 */
+	if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) {
+		get_ioctx(ctx);
+		spin_lock(&fput_lock);
+		list_add(&req->ki_list, &fput_head);
+		spin_unlock(&fput_lock);
+		queue_work(aio_wq, &fput_work);
+	} else
+		really_put_req(ctx, req);
+	return 1;
+}
+
+/* aio_put_req
+ *	Returns true if this put was the last user of the kiocb,
+ *	false if the request is still in use.
+ */
+int fastcall aio_put_req(struct kiocb *req)
+{
+	struct kioctx *ctx = req->ki_ctx;
+	int ret;
+	spin_lock_irq(&ctx->ctx_lock);
+	ret = __aio_put_req(ctx, req);
+	spin_unlock_irq(&ctx->ctx_lock);
+	if (ret)
+		put_ioctx(ctx);
+	return ret;
+}
+
+/*	Lookup an ioctx id.  ioctx_list is lockless for reads.
+ *	FIXME: this is O(n) and is only suitable for development.
+ */
+struct kioctx *lookup_ioctx(unsigned long ctx_id)
+{
+	struct kioctx *ioctx;
+	struct mm_struct *mm;
+
+	mm = current->mm;
+	read_lock(&mm->ioctx_list_lock);
+	for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next)
+		if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) {
+			get_ioctx(ioctx);
+			break;
+		}
+	read_unlock(&mm->ioctx_list_lock);
+
+	return ioctx;
+}
+
+/*
+ * use_mm
+ *	Makes the calling kernel thread take on the specified
+ *	mm context.
+ *	Called by the retry thread execute retries within the
+ *	iocb issuer's mm context, so that copy_from/to_user
+ *	operations work seamlessly for aio.
+ *	(Note: this routine is intended to be called only
+ *	from a kernel thread context)
+ */
+static void use_mm(struct mm_struct *mm)
+{
+	struct mm_struct *active_mm;
+	struct task_struct *tsk = current;
+
+	task_lock(tsk);
+	tsk->flags |= PF_BORROWED_MM;
+	active_mm = tsk->active_mm;
+	atomic_inc(&mm->mm_count);
+	tsk->mm = mm;
+	tsk->active_mm = mm;
+	activate_mm(active_mm, mm);
+	task_unlock(tsk);
+
+	mmdrop(active_mm);
+}
+
+/*
+ * unuse_mm
+ *	Reverses the effect of use_mm, i.e. releases the
+ *	specified mm context which was earlier taken on
+ *	by the calling kernel thread
+ *	(Note: this routine is intended to be called only
+ *	from a kernel thread context)
+ *
+ * Comments: Called with ctx->ctx_lock held. This nests
+ * task_lock instead ctx_lock.
+ */
+void unuse_mm(struct mm_struct *mm)
+{
+	struct task_struct *tsk = current;
+
+	task_lock(tsk);
+	tsk->flags &= ~PF_BORROWED_MM;
+	tsk->mm = NULL;
+	/* active_mm is still 'mm' */
+	enter_lazy_tlb(mm, tsk);
+	task_unlock(tsk);
+}
+
+/*
+ * Queue up a kiocb to be retried. Assumes that the kiocb
+ * has already been marked as kicked, and places it on
+ * the retry run list for the corresponding ioctx, if it
+ * isn't already queued. Returns 1 if it actually queued
+ * the kiocb (to tell the caller to activate the work
+ * queue to process it), or 0, if it found that it was
+ * already queued.
+ *
+ * Should be called with the spin lock iocb->ki_ctx->ctx_lock
+ * held
+ */
+static inline int __queue_kicked_iocb(struct kiocb *iocb)
+{
+	struct kioctx *ctx = iocb->ki_ctx;
+
+	if (list_empty(&iocb->ki_run_list)) {
+		list_add_tail(&iocb->ki_run_list,
+			&ctx->run_list);
+		iocb->ki_queued++;
+		return 1;
+	}
+	return 0;
+}
+
+/* aio_run_iocb
+ *	This is the core aio execution routine. It is
+ *	invoked both for initial i/o submission and
+ *	subsequent retries via the aio_kick_handler.
+ *	Expects to be invoked with iocb->ki_ctx->lock
+ *	already held. The lock is released and reaquired
+ *	as needed during processing.
+ *
+ * Calls the iocb retry method (already setup for the
+ * iocb on initial submission) for operation specific
+ * handling, but takes care of most of common retry
+ * execution details for a given iocb. The retry method
+ * needs to be non-blocking as far as possible, to avoid
+ * holding up other iocbs waiting to be serviced by the
+ * retry kernel thread.
+ *
+ * The trickier parts in this code have to do with
+ * ensuring that only one retry instance is in progress
+ * for a given iocb at any time. Providing that guarantee
+ * simplifies the coding of individual aio operations as
+ * it avoids various potential races.
+ */
+static ssize_t aio_run_iocb(struct kiocb *iocb)
+{
+	struct kioctx	*ctx = iocb->ki_ctx;
+	ssize_t (*retry)(struct kiocb *);
+	ssize_t ret;
+
+	if (iocb->ki_retried++ > 1024*1024) {
+		printk("Maximal retry count.  Bytes done %Zd\n",
+			iocb->ki_nbytes - iocb->ki_left);
+		return -EAGAIN;
+	}
+
+	if (!(iocb->ki_retried & 0xff)) {
+		pr_debug("%ld retry: %d of %d (kick %ld, Q %ld run %ld, wake %ld)\n",
+			iocb->ki_retried,
+			iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes,
+			iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups);
+	}
+
+	if (!(retry = iocb->ki_retry)) {
+		printk("aio_run_iocb: iocb->ki_retry = NULL\n");
+		return 0;
+	}
+
+	/*
+	 * We don't want the next retry iteration for this
+	 * operation to start until this one has returned and
+	 * updated the iocb state. However, wait_queue functions
+	 * can trigger a kick_iocb from interrupt context in the
+	 * meantime, indicating that data is available for the next
+	 * iteration. We want to remember that and enable the
+	 * next retry iteration _after_ we are through with
+	 * this one.
+	 *
+	 * So, in order to be able to register a "kick", but
+	 * prevent it from being queued now, we clear the kick
+	 * flag, but make the kick code *think* that the iocb is
+	 * still on the run list until we are actually done.
+	 * When we are done with this iteration, we check if
+	 * the iocb was kicked in the meantime and if so, queue
+	 * it up afresh.
+	 */
+
+	kiocbClearKicked(iocb);
+
+	/*
+	 * This is so that aio_complete knows it doesn't need to
+	 * pull the iocb off the run list (We can't just call
+	 * INIT_LIST_HEAD because we don't want a kick_iocb to
+	 * queue this on the run list yet)
+	 */
+	iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
+	spin_unlock_irq(&ctx->ctx_lock);
+
+	/* Quit retrying if the i/o has been cancelled */
+	if (kiocbIsCancelled(iocb)) {
+		ret = -EINTR;
+		aio_complete(iocb, ret, 0);
+		/* must not access the iocb after this */
+		goto out;
+	}
+
+	/*
+	 * Now we are all set to call the retry method in async
+	 * context. By setting this thread's io_wait context
+	 * to point to the wait queue entry inside the currently
+	 * running iocb for the duration of the retry, we ensure
+	 * that async notification wakeups are queued by the
+	 * operation instead of blocking waits, and when notified,
+	 * cause the iocb to be kicked for continuation (through
+	 * the aio_wake_function callback).
+	 */
+	BUG_ON(current->io_wait != NULL);
+	current->io_wait = &iocb->ki_wait;
+	ret = retry(iocb);
+	current->io_wait = NULL;
+
+	if (-EIOCBRETRY != ret) {
+ 		if (-EIOCBQUEUED != ret) {
+			BUG_ON(!list_empty(&iocb->ki_wait.task_list));
+			aio_complete(iocb, ret, 0);
+			/* must not access the iocb after this */
+		}
+	} else {
+		/*
+		 * Issue an additional retry to avoid waiting forever if
+		 * no waits were queued (e.g. in case of a short read).
+		 */
+		if (list_empty(&iocb->ki_wait.task_list))
+			kiocbSetKicked(iocb);
+	}
+out:
+	spin_lock_irq(&ctx->ctx_lock);
+
+	if (-EIOCBRETRY == ret) {
+		/*
+		 * OK, now that we are done with this iteration
+		 * and know that there is more left to go,
+		 * this is where we let go so that a subsequent
+		 * "kick" can start the next iteration
+		 */
+
+		/* will make __queue_kicked_iocb succeed from here on */
+		INIT_LIST_HEAD(&iocb->ki_run_list);
+		/* we must queue the next iteration ourselves, if it
+		 * has already been kicked */
+		if (kiocbIsKicked(iocb)) {
+			__queue_kicked_iocb(iocb);
+		}
+	}
+	return ret;
+}
+
+/*
+ * __aio_run_iocbs:
+ * 	Process all pending retries queued on the ioctx
+ * 	run list.
+ * Assumes it is operating within the aio issuer's mm
+ * context. Expects to be called with ctx->ctx_lock held
+ */
+static int __aio_run_iocbs(struct kioctx *ctx)
+{
+	struct kiocb *iocb;
+	int count = 0;
+	LIST_HEAD(run_list);
+
+	list_splice_init(&ctx->run_list, &run_list);
+	while (!list_empty(&run_list)) {
+		iocb = list_entry(run_list.next, struct kiocb,
+			ki_run_list);
+		list_del(&iocb->ki_run_list);
+		/*
+		 * Hold an extra reference while retrying i/o.
+		 */
+		iocb->ki_users++;       /* grab extra reference */
+		aio_run_iocb(iocb);
+		if (__aio_put_req(ctx, iocb))  /* drop extra ref */
+			put_ioctx(ctx);
+		count++;
+ 	}
+	aio_run++;
+	if (!list_empty(&ctx->run_list))
+		return 1;
+	return 0;
+}
+
+static void aio_queue_work(struct kioctx * ctx)
+{
+	unsigned long timeout;
+	/*
+	 * if someone is waiting, get the work started right
+	 * away, otherwise, use a longer delay
+	 */
+	smp_mb();
+	if (waitqueue_active(&ctx->wait))
+		timeout = 1;
+	else
+		timeout = HZ/10;
+	queue_delayed_work(aio_wq, &ctx->wq, timeout);
+}
+
+
+/*
+ * aio_run_iocbs:
+ * 	Process all pending retries queued on the ioctx
+ * 	run list.
+ * Assumes it is operating within the aio issuer's mm
+ * context.
+ */
+static inline void aio_run_iocbs(struct kioctx *ctx)
+{
+	int requeue;
+
+	spin_lock_irq(&ctx->ctx_lock);
+
+	requeue = __aio_run_iocbs(ctx);
+	spin_unlock_irq(&ctx->ctx_lock);
+	if (requeue)
+		aio_queue_work(ctx);
+}
+
+/*
+ * just like aio_run_iocbs, but keeps running them until
+ * the list stays empty
+ */
+static inline void aio_run_all_iocbs(struct kioctx *ctx)
+{
+	spin_lock_irq(&ctx->ctx_lock);
+	while (__aio_run_iocbs(ctx))
+		;
+	spin_unlock_irq(&ctx->ctx_lock);
+}
+
+/*
+ * aio_kick_handler:
+ * 	Work queue handler triggered to process pending
+ * 	retries on an ioctx. Takes on the aio issuer's
+ *	mm context before running the iocbs, so that
+ *	copy_xxx_user operates on the issuer's address
+ *      space.
+ * Run on aiod's context.
+ */
+static void aio_kick_handler(void *data)
+{
+	struct kioctx *ctx = data;
+	mm_segment_t oldfs = get_fs();
+	int requeue;
+
+	set_fs(USER_DS);
+	use_mm(ctx->mm);
+	spin_lock_irq(&ctx->ctx_lock);
+	requeue =__aio_run_iocbs(ctx);
+ 	unuse_mm(ctx->mm);
+	spin_unlock_irq(&ctx->ctx_lock);
+	set_fs(oldfs);
+	/*
+	 * we're in a worker thread already, don't use queue_delayed_work,
+	 */
+	if (requeue)
+		queue_work(aio_wq, &ctx->wq);
+}
+
+
+/*
+ * Called by kick_iocb to queue the kiocb for retry
+ * and if required activate the aio work queue to process
+ * it
+ */
+void queue_kicked_iocb(struct kiocb *iocb)
+{
+ 	struct kioctx	*ctx = iocb->ki_ctx;
+	unsigned long flags;
+	int run = 0;
+
+	WARN_ON((!list_empty(&iocb->ki_wait.task_list)));
+
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+	run = __queue_kicked_iocb(iocb);
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+	if (run) {
+		aio_queue_work(ctx);
+		aio_wakeups++;
+	}
+}
+
+/*
+ * kick_iocb:
+ *      Called typically from a wait queue callback context
+ *      (aio_wake_function) to trigger a retry of the iocb.
+ *      The retry is usually executed by aio workqueue
+ *      threads (See aio_kick_handler).
+ */
+void fastcall kick_iocb(struct kiocb *iocb)
+{
+	/* sync iocbs are easy: they can only ever be executing from a 
+	 * single context. */
+	if (is_sync_kiocb(iocb)) {
+		kiocbSetKicked(iocb);
+	        wake_up_process(iocb->ki_obj.tsk);
+		return;
+	}
+
+	iocb->ki_kicked++;
+	/* If its already kicked we shouldn't queue it again */
+	if (!kiocbTryKick(iocb)) {
+		queue_kicked_iocb(iocb);
+	}
+}
+EXPORT_SYMBOL(kick_iocb);
+
+/* aio_complete
+ *	Called when the io request on the given iocb is complete.
+ *	Returns true if this is the last user of the request.  The 
+ *	only other user of the request can be the cancellation code.
+ */
+int fastcall aio_complete(struct kiocb *iocb, long res, long res2)
+{
+	struct kioctx	*ctx = iocb->ki_ctx;
+	struct aio_ring_info	*info;
+	struct aio_ring	*ring;
+	struct io_event	*event;
+	unsigned long	flags;
+	unsigned long	tail;
+	int		ret;
+
+	/* Special case handling for sync iocbs: events go directly
+	 * into the iocb for fast handling.  Note that this will not 
+	 * work if we allow sync kiocbs to be cancelled. in which
+	 * case the usage count checks will have to move under ctx_lock
+	 * for all cases.
+	 */
+	if (is_sync_kiocb(iocb)) {
+		int ret;
+
+		iocb->ki_user_data = res;
+		if (iocb->ki_users == 1) {
+			iocb->ki_users = 0;
+			ret = 1;
+		} else {
+			spin_lock_irq(&ctx->ctx_lock);
+			iocb->ki_users--;
+			ret = (0 == iocb->ki_users);
+			spin_unlock_irq(&ctx->ctx_lock);
+		}
+		/* sync iocbs put the task here for us */
+		wake_up_process(iocb->ki_obj.tsk);
+		return ret;
+	}
+
+	info = &ctx->ring_info;
+
+	/* add a completion event to the ring buffer.
+	 * must be done holding ctx->ctx_lock to prevent
+	 * other code from messing with the tail
+	 * pointer since we might be called from irq
+	 * context.
+	 */
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+
+	if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
+		list_del_init(&iocb->ki_run_list);
+
+	/*
+	 * cancelled requests don't get events, userland was given one
+	 * when the event got cancelled.
+	 */
+	if (kiocbIsCancelled(iocb))
+		goto put_rq;
+
+	ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
+
+	tail = info->tail;
+	event = aio_ring_event(info, tail, KM_IRQ0);
+	tail = (tail + 1) % info->nr;
+
+	event->obj = (u64)(unsigned long)iocb->ki_obj.user;
+	event->data = iocb->ki_user_data;
+	event->res = res;
+	event->res2 = res2;
+
+	dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
+		ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
+		res, res2);
+
+	/* after flagging the request as done, we
+	 * must never even look at it again
+	 */
+	smp_wmb();	/* make event visible before updating tail */
+
+	info->tail = tail;
+	ring->tail = tail;
+
+	put_aio_ring_event(event, KM_IRQ0);
+	kunmap_atomic(ring, KM_IRQ1);
+
+	pr_debug("added to ring %p at [%lu]\n", iocb, tail);
+
+	pr_debug("%ld retries: %d of %d (kicked %ld, Q %ld run %ld wake %ld)\n",
+		iocb->ki_retried,
+		iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes,
+		iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups);
+put_rq:
+	/* everything turned out well, dispose of the aiocb. */
+	ret = __aio_put_req(ctx, iocb);
+
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+
+	if (waitqueue_active(&ctx->wait))
+		wake_up(&ctx->wait);
+
+	if (ret)
+		put_ioctx(ctx);
+
+	return ret;
+}
+
+/* aio_read_evt
+ *	Pull an event off of the ioctx's event ring.  Returns the number of 
+ *	events fetched (0 or 1 ;-)
+ *	FIXME: make this use cmpxchg.
+ *	TODO: make the ringbuffer user mmap()able (requires FIXME).
+ */
+static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
+{
+	struct aio_ring_info *info = &ioctx->ring_info;
+	struct aio_ring *ring;
+	unsigned long head;
+	int ret = 0;
+
+	ring = kmap_atomic(info->ring_pages[0], KM_USER0);
+	dprintk("in aio_read_evt h%lu t%lu m%lu\n",
+		 (unsigned long)ring->head, (unsigned long)ring->tail,
+		 (unsigned long)ring->nr);
+
+	if (ring->head == ring->tail)
+		goto out;
+
+	spin_lock(&info->ring_lock);
+
+	head = ring->head % info->nr;
+	if (head != ring->tail) {
+		struct io_event *evp = aio_ring_event(info, head, KM_USER1);
+		*ent = *evp;
+		head = (head + 1) % info->nr;
+		smp_mb(); /* finish reading the event before updatng the head */
+		ring->head = head;
+		ret = 1;
+		put_aio_ring_event(evp, KM_USER1);
+	}
+	spin_unlock(&info->ring_lock);
+
+out:
+	kunmap_atomic(ring, KM_USER0);
+	dprintk("leaving aio_read_evt: %d  h%lu t%lu\n", ret,
+		 (unsigned long)ring->head, (unsigned long)ring->tail);
+	return ret;
+}
+
+struct aio_timeout {
+	struct timer_list	timer;
+	int			timed_out;
+	struct task_struct	*p;
+};
+
+static void timeout_func(unsigned long data)
+{
+	struct aio_timeout *to = (struct aio_timeout *)data;
+
+	to->timed_out = 1;
+	wake_up_process(to->p);
+}
+
+static inline void init_timeout(struct aio_timeout *to)
+{
+	init_timer(&to->timer);
+	to->timer.data = (unsigned long)to;
+	to->timer.function = timeout_func;
+	to->timed_out = 0;
+	to->p = current;
+}
+
+static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
+			       const struct timespec *ts)
+{
+	to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
+	if (time_after(to->timer.expires, jiffies))
+		add_timer(&to->timer);
+	else
+		to->timed_out = 1;
+}
+
+static inline void clear_timeout(struct aio_timeout *to)
+{
+	del_singleshot_timer_sync(&to->timer);
+}
+
+static int read_events(struct kioctx *ctx,
+			long min_nr, long nr,
+			struct io_event __user *event,
+			struct timespec __user *timeout)
+{
+	long			start_jiffies = jiffies;
+	struct task_struct	*tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
+	int			ret;
+	int			i = 0;
+	struct io_event		ent;
+	struct aio_timeout	to;
+	int 			event_loop = 0; /* testing only */
+	int			retry = 0;
+
+	/* needed to zero any padding within an entry (there shouldn't be 
+	 * any, but C is fun!
+	 */
+	memset(&ent, 0, sizeof(ent));
+retry:
+	ret = 0;
+	while (likely(i < nr)) {
+		ret = aio_read_evt(ctx, &ent);
+		if (unlikely(ret <= 0))
+			break;
+
+		dprintk("read event: %Lx %Lx %Lx %Lx\n",
+			ent.data, ent.obj, ent.res, ent.res2);
+
+		/* Could we split the check in two? */
+		ret = -EFAULT;
+		if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
+			dprintk("aio: lost an event due to EFAULT.\n");
+			break;
+		}
+		ret = 0;
+
+		/* Good, event copied to userland, update counts. */
+		event ++;
+		i ++;
+	}
+
+	if (min_nr <= i)
+		return i;
+	if (ret)
+		return ret;
+
+	/* End fast path */
+
+	/* racey check, but it gets redone */
+	if (!retry && unlikely(!list_empty(&ctx->run_list))) {
+		retry = 1;
+		aio_run_all_iocbs(ctx);
+		goto retry;
+	}
+
+	init_timeout(&to);
+	if (timeout) {
+		struct timespec	ts;
+		ret = -EFAULT;
+		if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
+			goto out;
+
+		set_timeout(start_jiffies, &to, &ts);
+	}
+
+	while (likely(i < nr)) {
+		add_wait_queue_exclusive(&ctx->wait, &wait);
+		do {
+			set_task_state(tsk, TASK_INTERRUPTIBLE);
+			ret = aio_read_evt(ctx, &ent);
+			if (ret)
+				break;
+			if (min_nr <= i)
+				break;
+			ret = 0;
+			if (to.timed_out)	/* Only check after read evt */
+				break;
+			schedule();
+			event_loop++;
+			if (signal_pending(tsk)) {
+				ret = -EINTR;
+				break;
+			}
+			/*ret = aio_read_evt(ctx, &ent);*/
+		} while (1) ;
+
+		set_task_state(tsk, TASK_RUNNING);
+		remove_wait_queue(&ctx->wait, &wait);
+
+		if (unlikely(ret <= 0))
+			break;
+
+		ret = -EFAULT;
+		if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
+			dprintk("aio: lost an event due to EFAULT.\n");
+			break;
+		}
+
+		/* Good, event copied to userland, update counts. */
+		event ++;
+		i ++;
+	}
+
+	if (timeout)
+		clear_timeout(&to);
+out:
+	pr_debug("event loop executed %d times\n", event_loop);
+	pr_debug("aio_run %ld\n", aio_run);
+	pr_debug("aio_wakeups %ld\n", aio_wakeups);
+	return i ? i : ret;
+}
+
+/* Take an ioctx and remove it from the list of ioctx's.  Protects 
+ * against races with itself via ->dead.
+ */
+static void io_destroy(struct kioctx *ioctx)
+{
+	struct mm_struct *mm = current->mm;
+	struct kioctx **tmp;
+	int was_dead;
+
+	/* delete the entry from the list is someone else hasn't already */
+	write_lock(&mm->ioctx_list_lock);
+	was_dead = ioctx->dead;
+	ioctx->dead = 1;
+	for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx;
+	     tmp = &(*tmp)->next)
+		;
+	if (*tmp)
+		*tmp = ioctx->next;
+	write_unlock(&mm->ioctx_list_lock);
+
+	dprintk("aio_release(%p)\n", ioctx);
+	if (likely(!was_dead))
+		put_ioctx(ioctx);	/* twice for the list */
+
+	aio_cancel_all(ioctx);
+	wait_for_all_aios(ioctx);
+	put_ioctx(ioctx);	/* once for the lookup */
+}
+
+/* sys_io_setup:
+ *	Create an aio_context capable of receiving at least nr_events.
+ *	ctxp must not point to an aio_context that already exists, and
+ *	must be initialized to 0 prior to the call.  On successful
+ *	creation of the aio_context, *ctxp is filled in with the resulting 
+ *	handle.  May fail with -EINVAL if *ctxp is not initialized,
+ *	if the specified nr_events exceeds internal limits.  May fail 
+ *	with -EAGAIN if the specified nr_events exceeds the user's limit 
+ *	of available events.  May fail with -ENOMEM if insufficient kernel
+ *	resources are available.  May fail with -EFAULT if an invalid
+ *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
+ *	implemented.
+ */
+asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp)
+{
+	struct kioctx *ioctx = NULL;
+	unsigned long ctx;
+	long ret;
+
+	ret = get_user(ctx, ctxp);
+	if (unlikely(ret))
+		goto out;
+
+	ret = -EINVAL;
+	if (unlikely(ctx || (int)nr_events <= 0)) {
+		pr_debug("EINVAL: io_setup: ctx or nr_events > max\n");
+		goto out;
+	}
+
+	ioctx = ioctx_alloc(nr_events);
+	ret = PTR_ERR(ioctx);
+	if (!IS_ERR(ioctx)) {
+		ret = put_user(ioctx->user_id, ctxp);
+		if (!ret)
+			return 0;
+
+		get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
+		io_destroy(ioctx);
+	}
+
+out:
+	return ret;
+}
+
+/* sys_io_destroy:
+ *	Destroy the aio_context specified.  May cancel any outstanding 
+ *	AIOs and block on completion.  Will fail with -ENOSYS if not
+ *	implemented.  May fail with -EFAULT if the context pointed to
+ *	is invalid.
+ */
+asmlinkage long sys_io_destroy(aio_context_t ctx)
+{
+	struct kioctx *ioctx = lookup_ioctx(ctx);
+	if (likely(NULL != ioctx)) {
+		io_destroy(ioctx);
+		return 0;
+	}
+	pr_debug("EINVAL: io_destroy: invalid context id\n");
+	return -EINVAL;
+}
+
+/*
+ * Default retry method for aio_read (also used for first time submit)
+ * Responsible for updating iocb state as retries progress
+ */
+static ssize_t aio_pread(struct kiocb *iocb)
+{
+	struct file *file = iocb->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	ssize_t ret = 0;
+
+	ret = file->f_op->aio_read(iocb, iocb->ki_buf,
+		iocb->ki_left, iocb->ki_pos);
+
+	/*
+	 * Can't just depend on iocb->ki_left to determine
+	 * whether we are done. This may have been a short read.
+	 */
+	if (ret > 0) {
+		iocb->ki_buf += ret;
+		iocb->ki_left -= ret;
+		/*
+		 * For pipes and sockets we return once we have
+		 * some data; for regular files we retry till we
+		 * complete the entire read or find that we can't
+		 * read any more data (e.g short reads).
+		 */
+		if (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))
+			ret = -EIOCBRETRY;
+	}
+
+	/* This means we must have transferred all that we could */
+	/* No need to retry anymore */
+	if ((ret == 0) || (iocb->ki_left == 0))
+		ret = iocb->ki_nbytes - iocb->ki_left;
+
+	return ret;
+}
+
+/*
+ * Default retry method for aio_write (also used for first time submit)
+ * Responsible for updating iocb state as retries progress
+ */
+static ssize_t aio_pwrite(struct kiocb *iocb)
+{
+	struct file *file = iocb->ki_filp;
+	ssize_t ret = 0;
+
+	ret = file->f_op->aio_write(iocb, iocb->ki_buf,
+		iocb->ki_left, iocb->ki_pos);
+
+	if (ret > 0) {
+		iocb->ki_buf += ret;
+		iocb->ki_left -= ret;
+
+		ret = -EIOCBRETRY;
+	}
+
+	/* This means we must have transferred all that we could */
+	/* No need to retry anymore */
+	if ((ret == 0) || (iocb->ki_left == 0))
+		ret = iocb->ki_nbytes - iocb->ki_left;
+
+	return ret;
+}
+
+static ssize_t aio_fdsync(struct kiocb *iocb)
+{
+	struct file *file = iocb->ki_filp;
+	ssize_t ret = -EINVAL;
+
+	if (file->f_op->aio_fsync)
+		ret = file->f_op->aio_fsync(iocb, 1);
+	return ret;
+}
+
+static ssize_t aio_fsync(struct kiocb *iocb)
+{
+	struct file *file = iocb->ki_filp;
+	ssize_t ret = -EINVAL;
+
+	if (file->f_op->aio_fsync)
+		ret = file->f_op->aio_fsync(iocb, 0);
+	return ret;
+}
+
+/*
+ * aio_setup_iocb:
+ *	Performs the initial checks and aio retry method
+ *	setup for the kiocb at the time of io submission.
+ */
+ssize_t aio_setup_iocb(struct kiocb *kiocb)
+{
+	struct file *file = kiocb->ki_filp;
+	ssize_t ret = 0;
+
+	switch (kiocb->ki_opcode) {
+	case IOCB_CMD_PREAD:
+		ret = -EBADF;
+		if (unlikely(!(file->f_mode & FMODE_READ)))
+			break;
+		ret = -EFAULT;
+		if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
+			kiocb->ki_left)))
+			break;
+		ret = -EINVAL;
+		if (file->f_op->aio_read)
+			kiocb->ki_retry = aio_pread;
+		break;
+	case IOCB_CMD_PWRITE:
+		ret = -EBADF;
+		if (unlikely(!(file->f_mode & FMODE_WRITE)))
+			break;
+		ret = -EFAULT;
+		if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
+			kiocb->ki_left)))
+			break;
+		ret = -EINVAL;
+		if (file->f_op->aio_write)
+			kiocb->ki_retry = aio_pwrite;
+		break;
+	case IOCB_CMD_FDSYNC:
+		ret = -EINVAL;
+		if (file->f_op->aio_fsync)
+			kiocb->ki_retry = aio_fdsync;
+		break;
+	case IOCB_CMD_FSYNC:
+		ret = -EINVAL;
+		if (file->f_op->aio_fsync)
+			kiocb->ki_retry = aio_fsync;
+		break;
+	default:
+		dprintk("EINVAL: io_submit: no operation provided\n");
+		ret = -EINVAL;
+	}
+
+	if (!kiocb->ki_retry)
+		return ret;
+
+	return 0;
+}
+
+/*
+ * aio_wake_function:
+ * 	wait queue callback function for aio notification,
+ * 	Simply triggers a retry of the operation via kick_iocb.
+ *
+ * 	This callback is specified in the wait queue entry in
+ *	a kiocb	(current->io_wait points to this wait queue
+ *	entry when an aio operation executes; it is used
+ * 	instead of a synchronous wait when an i/o blocking
+ *	condition is encountered during aio).
+ *
+ * Note:
+ * This routine is executed with the wait queue lock held.
+ * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests
+ * the ioctx lock inside the wait queue lock. This is safe
+ * because this callback isn't used for wait queues which
+ * are nested inside ioctx lock (i.e. ctx->wait)
+ */
+int aio_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+	struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait);
+
+	list_del_init(&wait->task_list);
+	kick_iocb(iocb);
+	return 1;
+}
+
+int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
+			 struct iocb *iocb)
+{
+	struct kiocb *req;
+	struct file *file;
+	ssize_t ret;
+
+	/* enforce forwards compatibility on users */
+	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 ||
+		     iocb->aio_reserved3)) {
+		pr_debug("EINVAL: io_submit: reserve field set\n");
+		return -EINVAL;
+	}
+
+	/* prevent overflows */
+	if (unlikely(
+	    (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
+	    (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
+	    ((ssize_t)iocb->aio_nbytes < 0)
+	   )) {
+		pr_debug("EINVAL: io_submit: overflow check\n");
+		return -EINVAL;
+	}
+
+	file = fget(iocb->aio_fildes);
+	if (unlikely(!file))
+		return -EBADF;
+
+	req = aio_get_req(ctx);		/* returns with 2 references to req */
+	if (unlikely(!req)) {
+		fput(file);
+		return -EAGAIN;
+	}
+
+	req->ki_filp = file;
+	iocb->aio_key = req->ki_key;
+	ret = put_user(iocb->aio_key, &user_iocb->aio_key);
+	if (unlikely(ret)) {
+		dprintk("EFAULT: aio_key\n");
+		goto out_put_req;
+	}
+
+	req->ki_obj.user = user_iocb;
+	req->ki_user_data = iocb->aio_data;
+	req->ki_pos = iocb->aio_offset;
+
+	req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
+	req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
+	req->ki_opcode = iocb->aio_lio_opcode;
+	init_waitqueue_func_entry(&req->ki_wait, aio_wake_function);
+	INIT_LIST_HEAD(&req->ki_wait.task_list);
+	req->ki_run_list.next = req->ki_run_list.prev = NULL;
+	req->ki_retry = NULL;
+	req->ki_retried = 0;
+	req->ki_kicked = 0;
+	req->ki_queued = 0;
+	aio_run = 0;
+	aio_wakeups = 0;
+
+	ret = aio_setup_iocb(req);
+
+	if (ret)
+		goto out_put_req;
+
+	spin_lock_irq(&ctx->ctx_lock);
+	list_add_tail(&req->ki_run_list, &ctx->run_list);
+	/* drain the run list */
+	while (__aio_run_iocbs(ctx))
+		;
+	spin_unlock_irq(&ctx->ctx_lock);
+	aio_put_req(req);	/* drop extra ref to req */
+	return 0;
+
+out_put_req:
+	aio_put_req(req);	/* drop extra ref to req */
+	aio_put_req(req);	/* drop i/o ref to req */
+	return ret;
+}
+
+/* sys_io_submit:
+ *	Queue the nr iocbs pointed to by iocbpp for processing.  Returns
+ *	the number of iocbs queued.  May return -EINVAL if the aio_context
+ *	specified by ctx_id is invalid, if nr is < 0, if the iocb at
+ *	*iocbpp[0] is not properly initialized, if the operation specified
+ *	is invalid for the file descriptor in the iocb.  May fail with
+ *	-EFAULT if any of the data structures point to invalid data.  May
+ *	fail with -EBADF if the file descriptor specified in the first
+ *	iocb is invalid.  May fail with -EAGAIN if insufficient resources
+ *	are available to queue any iocbs.  Will return 0 if nr is 0.  Will
+ *	fail with -ENOSYS if not implemented.
+ */
+asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr,
+			      struct iocb __user * __user *iocbpp)
+{
+	struct kioctx *ctx;
+	long ret = 0;
+	int i;
+
+	if (unlikely(nr < 0))
+		return -EINVAL;
+
+	if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
+		return -EFAULT;
+
+	ctx = lookup_ioctx(ctx_id);
+	if (unlikely(!ctx)) {
+		pr_debug("EINVAL: io_submit: invalid context id\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * AKPM: should this return a partial result if some of the IOs were
+	 * successfully submitted?
+	 */
+	for (i=0; i<nr; i++) {
+		struct iocb __user *user_iocb;
+		struct iocb tmp;
+
+		if (unlikely(__get_user(user_iocb, iocbpp + i))) {
+			ret = -EFAULT;
+			break;
+		}
+
+		if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
+			ret = -EFAULT;
+			break;
+		}
+
+		ret = io_submit_one(ctx, user_iocb, &tmp);
+		if (ret)
+			break;
+	}
+
+	put_ioctx(ctx);
+	return i ? i : ret;
+}
+
+/* lookup_kiocb
+ *	Finds a given iocb for cancellation.
+ *	MUST be called with ctx->ctx_lock held.
+ */
+struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
+{
+	struct list_head *pos;
+	/* TODO: use a hash or array, this sucks. */
+	list_for_each(pos, &ctx->active_reqs) {
+		struct kiocb *kiocb = list_kiocb(pos);
+		if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
+			return kiocb;
+	}
+	return NULL;
+}
+
+/* sys_io_cancel:
+ *	Attempts to cancel an iocb previously passed to io_submit.  If
+ *	the operation is successfully cancelled, the resulting event is
+ *	copied into the memory pointed to by result without being placed
+ *	into the completion queue and 0 is returned.  May fail with
+ *	-EFAULT if any of the data structures pointed to are invalid.
+ *	May fail with -EINVAL if aio_context specified by ctx_id is
+ *	invalid.  May fail with -EAGAIN if the iocb specified was not
+ *	cancelled.  Will fail with -ENOSYS if not implemented.
+ */
+asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
+			      struct io_event __user *result)
+{
+	int (*cancel)(struct kiocb *iocb, struct io_event *res);
+	struct kioctx *ctx;
+	struct kiocb *kiocb;
+	u32 key;
+	int ret;
+
+	ret = get_user(key, &iocb->aio_key);
+	if (unlikely(ret))
+		return -EFAULT;
+
+	ctx = lookup_ioctx(ctx_id);
+	if (unlikely(!ctx))
+		return -EINVAL;
+
+	spin_lock_irq(&ctx->ctx_lock);
+	ret = -EAGAIN;
+	kiocb = lookup_kiocb(ctx, iocb, key);
+	if (kiocb && kiocb->ki_cancel) {
+		cancel = kiocb->ki_cancel;
+		kiocb->ki_users ++;
+		kiocbSetCancelled(kiocb);
+	} else
+		cancel = NULL;
+	spin_unlock_irq(&ctx->ctx_lock);
+
+	if (NULL != cancel) {
+		struct io_event tmp;
+		pr_debug("calling cancel\n");
+		memset(&tmp, 0, sizeof(tmp));
+		tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
+		tmp.data = kiocb->ki_user_data;
+		ret = cancel(kiocb, &tmp);
+		if (!ret) {
+			/* Cancellation succeeded -- copy the result
+			 * into the user's buffer.
+			 */
+			if (copy_to_user(result, &tmp, sizeof(tmp)))
+				ret = -EFAULT;
+		}
+	} else
+		printk(KERN_DEBUG "iocb has no cancel operation\n");
+
+	put_ioctx(ctx);
+
+	return ret;
+}
+
+/* io_getevents:
+ *	Attempts to read at least min_nr events and up to nr events from
+ *	the completion queue for the aio_context specified by ctx_id.  May
+ *	fail with -EINVAL if ctx_id is invalid, if min_nr is out of range,
+ *	if nr is out of range, if when is out of range.  May fail with
+ *	-EFAULT if any of the memory specified to is invalid.  May return
+ *	0 or < min_nr if no events are available and the timeout specified
+ *	by when	has elapsed, where when == NULL specifies an infinite
+ *	timeout.  Note that the timeout pointed to by when is relative and
+ *	will be updated if not NULL and the operation blocks.  Will fail
+ *	with -ENOSYS if not implemented.
+ */
+asmlinkage long sys_io_getevents(aio_context_t ctx_id,
+				 long min_nr,
+				 long nr,
+				 struct io_event __user *events,
+				 struct timespec __user *timeout)
+{
+	struct kioctx *ioctx = lookup_ioctx(ctx_id);
+	long ret = -EINVAL;
+
+	if (likely(ioctx)) {
+		if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0))
+			ret = read_events(ioctx, min_nr, nr, events, timeout);
+		put_ioctx(ioctx);
+	}
+
+	return ret;
+}
+
+__initcall(aio_setup);
+
+EXPORT_SYMBOL(aio_complete);
+EXPORT_SYMBOL(aio_put_req);
+EXPORT_SYMBOL(wait_on_sync_kiocb);