init android origin source code

1 files changed, 1861 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/fs/aio.c b/ANDROID_3.4.5/fs/aio.c
new file mode 100644
index 00000000..e7f2fad7
--- /dev/null
+++ b/ANDROID_3.4.5/fs/aio.c
@@ -0,0 +1,1861 @@
+/*
+ *	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/export.h>
+#include <linux/syscalls.h>
+#include <linux/backing-dev.h>
+#include <linux/uio.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/mmu_context.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 <linux/eventfd.h>
+#include <linux/blkdev.h>
+#include <linux/compat.h>
+
+#include <asm/kmap_types.h>
+#include <asm/uaccess.h>
+
+#if DEBUG > 1
+#define dprintk		printk
+#else
+#define dprintk(x...)	do { ; } while (0)
+#endif
+
+/*------ sysctl variables----*/
+static DEFINE_SPINLOCK(aio_nr_lock);
+unsigned long aio_nr;		/* current system wide number of aio requests */
+unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
+/*----end sysctl variables---*/
+
+static struct kmem_cache	*kiocb_cachep;
+static struct kmem_cache	*kioctx_cachep;
+
+static struct workqueue_struct *aio_wq;
+
+/* Used for rare fput completion. */
+static void aio_fput_routine(struct work_struct *);
+static DECLARE_WORK(fput_work, aio_fput_routine);
+
+static DEFINE_SPINLOCK(fput_lock);
+static LIST_HEAD(fput_head);
+
+static void aio_kick_handler(struct work_struct *);
+static void aio_queue_work(struct kioctx *);
+
+/* 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(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
+	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
+
+	aio_wq = alloc_workqueue("aio", 0, 1);	/* used to limit concurrency */
+	BUG_ON(!aio_wq);
+
+	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
+
+	return 0;
+}
+__initcall(aio_setup);
+
+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) {
+		BUG_ON(ctx->mm != current->mm);
+		vm_munmap(info->mmap_base, info->mmap_size);
+	}
+
+	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 = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
+		if (!info->ring_pages)
+			return -ENOMEM;
+	}
+
+	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_ANONYMOUS|MAP_PRIVATE,
+				  0);
+	if (IS_ERR((void *)info->mmap_base)) {
+		up_write(&ctx->mm->mmap_sem);
+		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]);
+	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);
+
+	return 0;
+}
+
+
+/* aio_ring_event: returns a pointer to the event at the given index from
+ * kmap_atomic().  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) ({					\
+	unsigned pos = (nr) + AIO_EVENTS_OFFSET;			\
+	struct io_event *__event;					\
+	__event = kmap_atomic(						\
+			(info)->ring_pages[pos / AIO_EVENTS_PER_PAGE]); \
+	__event += pos % AIO_EVENTS_PER_PAGE;				\
+	__event;							\
+})
+
+#define put_aio_ring_event(event) do {		\
+	struct io_event *__event = (event);	\
+	(void)__event;				\
+	kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK)); \
+} while(0)
+
+static void ctx_rcu_free(struct rcu_head *head)
+{
+	struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
+	kmem_cache_free(kioctx_cachep, ctx);
+}
+
+/* __put_ioctx
+ *	Called when the last user of an aio context has gone away,
+ *	and the struct needs to be freed.
+ */
+static void __put_ioctx(struct kioctx *ctx)
+{
+	unsigned nr_events = ctx->max_reqs;
+	BUG_ON(ctx->reqs_active);
+
+	cancel_delayed_work_sync(&ctx->wq);
+	aio_free_ring(ctx);
+	mmdrop(ctx->mm);
+	ctx->mm = NULL;
+	if (nr_events) {
+		spin_lock(&aio_nr_lock);
+		BUG_ON(aio_nr - nr_events > aio_nr);
+		aio_nr -= nr_events;
+		spin_unlock(&aio_nr_lock);
+	}
+	pr_debug("__put_ioctx: freeing %p\n", ctx);
+	call_rcu(&ctx->rcu_head, ctx_rcu_free);
+}
+
+static inline int try_get_ioctx(struct kioctx *kioctx)
+{
+	return atomic_inc_not_zero(&kioctx->users);
+}
+
+static inline void put_ioctx(struct kioctx *kioctx)
+{
+	BUG_ON(atomic_read(&kioctx->users) <= 0);
+	if (unlikely(atomic_dec_and_test(&kioctx->users)))
+		__put_ioctx(kioctx);
+}
+
+/* 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;
+	int err = -ENOMEM;
+
+	/* 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 || (unsigned long)nr_events > aio_max_nr)
+		return ERR_PTR(-EAGAIN);
+
+	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	ctx->max_reqs = nr_events;
+	mm = ctx->mm = current->mm;
+	atomic_inc(&mm->mm_count);
+
+	atomic_set(&ctx->users, 2);
+	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_DELAYED_WORK(&ctx->wq, aio_kick_handler);
+
+	if (aio_setup_ring(ctx) < 0)
+		goto out_freectx;
+
+	/* limit the number of system wide aios */
+	spin_lock(&aio_nr_lock);
+	if (aio_nr + nr_events > aio_max_nr ||
+	    aio_nr + nr_events < aio_nr) {
+		spin_unlock(&aio_nr_lock);
+		goto out_cleanup;
+	}
+	aio_nr += ctx->max_reqs;
+	spin_unlock(&aio_nr_lock);
+
+	/* now link into global list. */
+	spin_lock(&mm->ioctx_lock);
+	hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
+	spin_unlock(&mm->ioctx_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:
+	err = -EAGAIN;
+	aio_free_ring(ctx);
+out_freectx:
+	mmdrop(mm);
+	kmem_cache_free(kioctx_cachep, ctx);
+	dprintk("aio: error allocating ioctx %d\n", err);
+	return ERR_PTR(err);
+}
+
+/* kill_ctx
+ *	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 kill_ctx(struct kioctx *ctx)
+{
+	int (*cancel)(struct kiocb *, struct io_event *);
+	struct task_struct *tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
+	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);
+		}
+	}
+
+	if (!ctx->reqs_active)
+		goto out;
+
+	add_wait_queue(&ctx->wait, &wait);
+	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+	while (ctx->reqs_active) {
+		spin_unlock_irq(&ctx->ctx_lock);
+		io_schedule();
+		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+		spin_lock_irq(&ctx->ctx_lock);
+	}
+	__set_task_state(tsk, TASK_RUNNING);
+	remove_wait_queue(&ctx->wait, &wait);
+
+out:
+	spin_unlock_irq(&ctx->ctx_lock);
+}
+
+/* wait_on_sync_kiocb:
+ *	Waits on the given sync kiocb to complete.
+ */
+ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
+{
+	while (iocb->ki_users) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (!iocb->ki_users)
+			break;
+		io_schedule();
+	}
+	__set_current_state(TASK_RUNNING);
+	return iocb->ki_user_data;
+}
+EXPORT_SYMBOL(wait_on_sync_kiocb);
+
+/* 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 exit_aio(struct mm_struct *mm)
+{
+	struct kioctx *ctx;
+
+	while (!hlist_empty(&mm->ioctx_list)) {
+		ctx = hlist_entry(mm->ioctx_list.first, struct kioctx, list);
+		hlist_del_rcu(&ctx->list);
+
+		kill_ctx(ctx);
+
+		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);
+		/*
+		 * We don't need to bother with munmap() here -
+		 * exit_mmap(mm) is coming and it'll unmap everything.
+		 * Since aio_free_ring() uses non-zero ->mmap_size
+		 * as indicator that it needs to unmap the area,
+		 * just set it to 0; aio_free_ring() is the only
+		 * place that uses ->mmap_size, so it's safe.
+		 * That way we get all munmap done to current->mm -
+		 * all other callers have ctx->mm == current->mm.
+		 */
+		ctx->ring_info.mmap_size = 0;
+		put_ioctx(ctx);
+	}
+}
+
+/* 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 *__aio_get_req(struct kioctx *ctx)
+{
+	struct kiocb *req = NULL;
+
+	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
+	if (unlikely(!req))
+		return NULL;
+
+	req->ki_flags = 0;
+	req->ki_users = 2;
+	req->ki_key = 0;
+	req->ki_ctx = ctx;
+	req->ki_cancel = NULL;
+	req->ki_retry = NULL;
+	req->ki_dtor = NULL;
+	req->private = NULL;
+	req->ki_iovec = NULL;
+	INIT_LIST_HEAD(&req->ki_run_list);
+	req->ki_eventfd = NULL;
+
+	return req;
+}
+
+/*
+ * struct kiocb's are allocated in batches to reduce the number of
+ * times the ctx lock is acquired and released.
+ */
+#define KIOCB_BATCH_SIZE	32L
+struct kiocb_batch {
+	struct list_head head;
+	long count; /* number of requests left to allocate */
+};
+
+static void kiocb_batch_init(struct kiocb_batch *batch, long total)
+{
+	INIT_LIST_HEAD(&batch->head);
+	batch->count = total;
+}
+
+static void kiocb_batch_free(struct kioctx *ctx, struct kiocb_batch *batch)
+{
+	struct kiocb *req, *n;
+
+	if (list_empty(&batch->head))
+		return;
+
+	spin_lock_irq(&ctx->ctx_lock);
+	list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
+		list_del(&req->ki_batch);
+		list_del(&req->ki_list);
+		kmem_cache_free(kiocb_cachep, req);
+		ctx->reqs_active--;
+	}
+	if (unlikely(!ctx->reqs_active && ctx->dead))
+		wake_up_all(&ctx->wait);
+	spin_unlock_irq(&ctx->ctx_lock);
+}
+
+/*
+ * Allocate a batch of kiocbs.  This avoids taking and dropping the
+ * context lock a lot during setup.
+ */
+static int kiocb_batch_refill(struct kioctx *ctx, struct kiocb_batch *batch)
+{
+	unsigned short allocated, to_alloc;
+	long avail;
+	bool called_fput = false;
+	struct kiocb *req, *n;
+	struct aio_ring *ring;
+
+	to_alloc = min(batch->count, KIOCB_BATCH_SIZE);
+	for (allocated = 0; allocated < to_alloc; allocated++) {
+		req = __aio_get_req(ctx);
+		if (!req)
+			/* allocation failed, go with what we've got */
+			break;
+		list_add(&req->ki_batch, &batch->head);
+	}
+
+	if (allocated == 0)
+		goto out;
+
+retry:
+	spin_lock_irq(&ctx->ctx_lock);
+	ring = kmap_atomic(ctx->ring_info.ring_pages[0]);
+
+	avail = aio_ring_avail(&ctx->ring_info, ring) - ctx->reqs_active;
+	BUG_ON(avail < 0);
+	if (avail == 0 && !called_fput) {
+		/*
+		 * Handle a potential starvation case.  It is possible that
+		 * we hold the last reference on a struct file, causing us
+		 * to delay the final fput to non-irq context.  In this case,
+		 * ctx->reqs_active is artificially high.  Calling the fput
+		 * routine here may free up a slot in the event completion
+		 * ring, allowing this allocation to succeed.
+		 */
+		kunmap_atomic(ring);
+		spin_unlock_irq(&ctx->ctx_lock);
+		aio_fput_routine(NULL);
+		called_fput = true;
+		goto retry;
+	}
+
+	if (avail < allocated) {
+		/* Trim back the number of requests. */
+		list_for_each_entry_safe(req, n, &batch->head, ki_batch) {
+			list_del(&req->ki_batch);
+			kmem_cache_free(kiocb_cachep, req);
+			if (--allocated <= avail)
+				break;
+		}
+	}
+
+	batch->count -= allocated;
+	list_for_each_entry(req, &batch->head, ki_batch) {
+		list_add(&req->ki_list, &ctx->active_reqs);
+		ctx->reqs_active++;
+	}
+
+	kunmap_atomic(ring);
+	spin_unlock_irq(&ctx->ctx_lock);
+
+out:
+	return allocated;
+}
+
+static inline struct kiocb *aio_get_req(struct kioctx *ctx,
+					struct kiocb_batch *batch)
+{
+	struct kiocb *req;
+
+	if (list_empty(&batch->head))
+		if (kiocb_batch_refill(ctx, batch) == 0)
+			return NULL;
+	req = list_first_entry(&batch->head, struct kiocb, ki_batch);
+	list_del(&req->ki_batch);
+	return req;
+}
+
+static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
+{
+	assert_spin_locked(&ctx->ctx_lock);
+
+	if (req->ki_eventfd != NULL)
+		eventfd_ctx_put(req->ki_eventfd);
+	if (req->ki_dtor)
+		req->ki_dtor(req);
+	if (req->ki_iovec != &req->ki_inline_vec)
+		kfree(req->ki_iovec);
+	kmem_cache_free(kiocb_cachep, req);
+	ctx->reqs_active--;
+
+	if (unlikely(!ctx->reqs_active && ctx->dead))
+		wake_up_all(&ctx->wait);
+}
+
+static void aio_fput_routine(struct work_struct *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(s) */
+		if (req->ki_filp != NULL)
+			fput(req->ki_filp);
+
+		/* Link the iocb into the context's free list */
+		rcu_read_lock();
+		spin_lock_irq(&ctx->ctx_lock);
+		really_put_req(ctx, req);
+		/*
+		 * at that point ctx might've been killed, but actual
+		 * freeing is RCU'd
+		 */
+		spin_unlock_irq(&ctx->ctx_lock);
+		rcu_read_unlock();
+
+		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=%ld\n",
+		req, atomic_long_read(&req->ki_filp->f_count));
+
+	assert_spin_locked(&ctx->ctx_lock);
+
+	req->ki_users--;
+	BUG_ON(req->ki_users < 0);
+	if (likely(req->ki_users))
+		return 0;
+	list_del(&req->ki_list);		/* remove from active_reqs */
+	req->ki_cancel = NULL;
+	req->ki_retry = NULL;
+
+	/*
+	 * Try to optimize the aio and eventfd file* puts, by avoiding to
+	 * schedule work in case it is not final fput() time. In normal cases,
+	 * we would not be holding the last reference to the file*, so
+	 * this function will be executed w/out any aio kthread wakeup.
+	 */
+	if (unlikely(!fput_atomic(req->ki_filp))) {
+		spin_lock(&fput_lock);
+		list_add(&req->ki_list, &fput_head);
+		spin_unlock(&fput_lock);
+		schedule_work(&fput_work);
+	} else {
+		req->ki_filp = NULL;
+		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 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);
+	return ret;
+}
+EXPORT_SYMBOL(aio_put_req);
+
+static struct kioctx *lookup_ioctx(unsigned long ctx_id)
+{
+	struct mm_struct *mm = current->mm;
+	struct kioctx *ctx, *ret = NULL;
+	struct hlist_node *n;
+
+	rcu_read_lock();
+
+	hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
+		/*
+		 * RCU protects us against accessing freed memory but
+		 * we have to be careful not to get a reference when the
+		 * reference count already dropped to 0 (ctx->dead test
+		 * is unreliable because of races).
+		 */
+		if (ctx->user_id == ctx_id && !ctx->dead && try_get_ioctx(ctx)){
+			ret = ctx;
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * 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.
+ */
+static inline int __queue_kicked_iocb(struct kiocb *iocb)
+{
+	struct kioctx *ctx = iocb->ki_ctx;
+
+	assert_spin_locked(&ctx->ctx_lock);
+
+	if (list_empty(&iocb->ki_run_list)) {
+		list_add_tail(&iocb->ki_run_list,
+			&ctx->run_list);
+		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 reacquired
+ *	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 (!(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.
+	 */
+	ret = retry(iocb);
+
+	if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
+		/*
+		 * There's no easy way to restart the syscall since other AIO's
+		 * may be already running. Just fail this IO with EINTR.
+		 */
+		if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
+			     ret == -ERESTARTNOHAND || ret == -ERESTART_RESTARTBLOCK))
+			ret = -EINTR;
+		aio_complete(iocb, ret, 0);
+	}
+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);
+
+			/*
+			 * __queue_kicked_iocb will always return 1 here, because
+			 * iocb->ki_run_list is empty at this point so it should
+			 * be safe to unconditionally queue the context into the
+			 * work queue.
+			 */
+			aio_queue_work(ctx);
+		}
+	}
+	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.
+ */
+static int __aio_run_iocbs(struct kioctx *ctx)
+{
+	struct kiocb *iocb;
+	struct list_head run_list;
+
+	assert_spin_locked(&ctx->ctx_lock);
+
+	list_replace_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);
+		__aio_put_req(ctx, iocb);
+ 	}
+	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_all_iocbs:
+ *	Process all pending retries queued on the ioctx
+ *	run list, and keep running them until the list
+ *	stays empty.
+ * Assumes it is operating within the aio issuer's mm context.
+ */
+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(struct work_struct *work)
+{
+	struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
+	mm_segment_t oldfs = get_fs();
+	struct mm_struct *mm;
+	int requeue;
+
+	set_fs(USER_DS);
+	use_mm(ctx->mm);
+	spin_lock_irq(&ctx->ctx_lock);
+	requeue =__aio_run_iocbs(ctx);
+	mm = ctx->mm;
+	spin_unlock_irq(&ctx->ctx_lock);
+ 	unuse_mm(mm);
+	set_fs(oldfs);
+	/*
+	 * we're in a worker thread already; no point using non-zero delay
+	 */
+	if (requeue)
+		queue_delayed_work(aio_wq, &ctx->wq, 0);
+}
+
+
+/*
+ * Called by kick_iocb to queue the kiocb for retry
+ * and if required activate the aio work queue to process
+ * it
+ */
+static void try_queue_kicked_iocb(struct kiocb *iocb)
+{
+ 	struct kioctx	*ctx = iocb->ki_ctx;
+	unsigned long flags;
+	int run = 0;
+
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+	/* set this inside the lock so that we can't race with aio_run_iocb()
+	 * testing it and putting the iocb on the run list under the lock */
+	if (!kiocbTryKick(iocb))
+		run = __queue_kicked_iocb(iocb);
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+	if (run)
+		aio_queue_work(ctx);
+}
+
+/*
+ * kick_iocb:
+ *      Called typically from a wait queue callback context
+ *      to trigger a retry of the iocb.
+ *      The retry is usually executed by aio workqueue
+ *      threads (See aio_kick_handler).
+ */
+void 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;
+	}
+
+	try_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 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
+	 *  - the sync task with the iocb in its stack holds the single iocb
+	 *    ref, no other paths have a way to get another ref
+	 *  - the sync task helpfully left a reference to itself in the iocb
+	 */
+	if (is_sync_kiocb(iocb)) {
+		BUG_ON(iocb->ki_users != 1);
+		iocb->ki_user_data = res;
+		iocb->ki_users = 0;
+		wake_up_process(iocb->ki_obj.tsk);
+		return 1;
+	}
+
+	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]);
+
+	tail = info->tail;
+	event = aio_ring_event(info, tail);
+	if (++tail >= info->nr)
+		tail = 0;
+
+	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);
+	kunmap_atomic(ring);
+
+	pr_debug("added to ring %p at [%lu]\n", iocb, tail);
+
+	/*
+	 * Check if the user asked us to deliver the result through an
+	 * eventfd. The eventfd_signal() function is safe to be called
+	 * from IRQ context.
+	 */
+	if (iocb->ki_eventfd != NULL)
+		eventfd_signal(iocb->ki_eventfd, 1);
+
+put_rq:
+	/* everything turned out well, dispose of the aiocb. */
+	ret = __aio_put_req(ctx, iocb);
+
+	/*
+	 * We have to order our ring_info tail store above and test
+	 * of the wait list below outside the wait lock.  This is
+	 * like in wake_up_bit() where clearing a bit has to be
+	 * ordered with the unlocked test.
+	 */
+	smp_mb();
+
+	if (waitqueue_active(&ctx->wait))
+		wake_up(&ctx->wait);
+
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(aio_complete);
+
+/* 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]);
+	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);
+		*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);
+	}
+	spin_unlock(&info->ring_lock);
+
+out:
+	kunmap_atomic(ring);
+	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)
+{
+	setup_timer_on_stack(&to->timer, timeout_func, (unsigned long) to);
+	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			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;
+			if (unlikely(ctx->dead)) {
+				ret = -EINVAL;
+				break;
+			}
+			if (to.timed_out)	/* Only check after read evt */
+				break;
+			/* Try to only show up in io wait if there are ops
+			 *  in flight */
+			if (ctx->reqs_active)
+				io_schedule();
+			else
+				schedule();
+			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:
+	destroy_timer_on_stack(&to.timer);
+	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;
+	int was_dead;
+
+	/* delete the entry from the list is someone else hasn't already */
+	spin_lock(&mm->ioctx_lock);
+	was_dead = ioctx->dead;
+	ioctx->dead = 1;
+	hlist_del_rcu(&ioctx->list);
+	spin_unlock(&mm->ioctx_lock);
+
+	dprintk("aio_release(%p)\n", ioctx);
+	if (likely(!was_dead))
+		put_ioctx(ioctx);	/* twice for the list */
+
+	kill_ctx(ioctx);
+
+	/*
+	 * Wake up any waiters.  The setting of ctx->dead must be seen
+	 * by other CPUs at this point.  Right now, we rely on the
+	 * locking done by the above calls to ensure this consistency.
+	 */
+	wake_up_all(&ioctx->wait);
+}
+
+/* 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.
+ */
+SYSCALL_DEFINE2(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 || nr_events == 0)) {
+		pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
+		         ctx, nr_events);
+		goto out;
+	}
+
+	ioctx = ioctx_alloc(nr_events);
+	ret = PTR_ERR(ioctx);
+	if (!IS_ERR(ioctx)) {
+		ret = put_user(ioctx->user_id, ctxp);
+		if (ret)
+			io_destroy(ioctx);
+		put_ioctx(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 -EINVAL if the context pointed to
+ *	is invalid.
+ */
+SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
+{
+	struct kioctx *ioctx = lookup_ioctx(ctx);
+	if (likely(NULL != ioctx)) {
+		io_destroy(ioctx);
+		put_ioctx(ioctx);
+		return 0;
+	}
+	pr_debug("EINVAL: io_destroy: invalid context id\n");
+	return -EINVAL;
+}
+
+static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
+{
+	struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
+
+	BUG_ON(ret <= 0);
+
+	while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
+		ssize_t this = min((ssize_t)iov->iov_len, ret);
+		iov->iov_base += this;
+		iov->iov_len -= this;
+		iocb->ki_left -= this;
+		ret -= this;
+		if (iov->iov_len == 0) {
+			iocb->ki_cur_seg++;
+			iov++;
+		}
+	}
+
+	/* the caller should not have done more io than what fit in
+	 * the remaining iovecs */
+	BUG_ON(ret > 0 && iocb->ki_left == 0);
+}
+
+static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
+{
+	struct file *file = iocb->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
+			 unsigned long, loff_t);
+	ssize_t ret = 0;
+	unsigned short opcode;
+
+	if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
+		(iocb->ki_opcode == IOCB_CMD_PREAD)) {
+		rw_op = file->f_op->aio_read;
+		opcode = IOCB_CMD_PREADV;
+	} else {
+		rw_op = file->f_op->aio_write;
+		opcode = IOCB_CMD_PWRITEV;
+	}
+
+	/* This matches the pread()/pwrite() logic */
+	if (iocb->ki_pos < 0)
+		return -EINVAL;
+
+	do {
+		ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
+			    iocb->ki_nr_segs - iocb->ki_cur_seg,
+			    iocb->ki_pos);
+		if (ret > 0)
+			aio_advance_iovec(iocb, ret);
+
+	/* retry all partial writes.  retry partial reads as long as its a
+	 * regular file. */
+	} while (ret > 0 && iocb->ki_left > 0 &&
+		 (opcode == IOCB_CMD_PWRITEV ||
+		  (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
+
+	/* 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;
+
+	/* If we managed to write some out we return that, rather than
+	 * the eventual error. */
+	if (opcode == IOCB_CMD_PWRITEV
+	    && ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY
+	    && iocb->ki_nbytes - iocb->ki_left)
+		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;
+}
+
+static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
+{
+	ssize_t ret;
+
+#ifdef CONFIG_COMPAT
+	if (compat)
+		ret = compat_rw_copy_check_uvector(type,
+				(struct compat_iovec __user *)kiocb->ki_buf,
+				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
+				&kiocb->ki_iovec, 1);
+	else
+#endif
+		ret = rw_copy_check_uvector(type,
+				(struct iovec __user *)kiocb->ki_buf,
+				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
+				&kiocb->ki_iovec, 1);
+	if (ret < 0)
+		goto out;
+
+	ret = rw_verify_area(type, kiocb->ki_filp, &kiocb->ki_pos, ret);
+	if (ret < 0)
+		goto out;
+
+	kiocb->ki_nr_segs = kiocb->ki_nbytes;
+	kiocb->ki_cur_seg = 0;
+	/* ki_nbytes/left now reflect bytes instead of segs */
+	kiocb->ki_nbytes = ret;
+	kiocb->ki_left = ret;
+
+	ret = 0;
+out:
+	return ret;
+}
+
+static ssize_t aio_setup_single_vector(int type, struct file * file, struct kiocb *kiocb)
+{
+	int bytes;
+
+	bytes = rw_verify_area(type, file, &kiocb->ki_pos, kiocb->ki_left);
+	if (bytes < 0)
+		return bytes;
+
+	kiocb->ki_iovec = &kiocb->ki_inline_vec;
+	kiocb->ki_iovec->iov_base = kiocb->ki_buf;
+	kiocb->ki_iovec->iov_len = bytes;
+	kiocb->ki_nr_segs = 1;
+	kiocb->ki_cur_seg = 0;
+	return 0;
+}
+
+/*
+ * aio_setup_iocb:
+ *	Performs the initial checks and aio retry method
+ *	setup for the kiocb at the time of io submission.
+ */
+static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
+{
+	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 = aio_setup_single_vector(READ, file, kiocb);
+		if (ret)
+			break;
+		ret = -EINVAL;
+		if (file->f_op->aio_read)
+			kiocb->ki_retry = aio_rw_vect_retry;
+		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 = aio_setup_single_vector(WRITE, file, kiocb);
+		if (ret)
+			break;
+		ret = -EINVAL;
+		if (file->f_op->aio_write)
+			kiocb->ki_retry = aio_rw_vect_retry;
+		break;
+	case IOCB_CMD_PREADV:
+		ret = -EBADF;
+		if (unlikely(!(file->f_mode & FMODE_READ)))
+			break;
+		ret = aio_setup_vectored_rw(READ, kiocb, compat);
+		if (ret)
+			break;
+		ret = -EINVAL;
+		if (file->f_op->aio_read)
+			kiocb->ki_retry = aio_rw_vect_retry;
+		break;
+	case IOCB_CMD_PWRITEV:
+		ret = -EBADF;
+		if (unlikely(!(file->f_mode & FMODE_WRITE)))
+			break;
+		ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
+		if (ret)
+			break;
+		ret = -EINVAL;
+		if (file->f_op->aio_write)
+			kiocb->ki_retry = aio_rw_vect_retry;
+		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;
+}
+
+static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
+			 struct iocb *iocb, struct kiocb_batch *batch,
+			 bool compat)
+{
+	struct kiocb *req;
+	struct file *file;
+	ssize_t ret;
+
+	/* enforce forwards compatibility on users */
+	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
+		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, batch);  /* returns with 2 references to req */
+	if (unlikely(!req)) {
+		fput(file);
+		return -EAGAIN;
+	}
+	req->ki_filp = file;
+	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
+		/*
+		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
+		 * instance of the file* now. The file descriptor must be
+		 * an eventfd() fd, and will be signaled for each completed
+		 * event using the eventfd_signal() function.
+		 */
+		req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
+		if (IS_ERR(req->ki_eventfd)) {
+			ret = PTR_ERR(req->ki_eventfd);
+			req->ki_eventfd = NULL;
+			goto out_put_req;
+		}
+	}
+
+	ret = put_user(req->ki_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;
+
+	ret = aio_setup_iocb(req, compat);
+
+	if (ret)
+		goto out_put_req;
+
+	spin_lock_irq(&ctx->ctx_lock);
+	/*
+	 * We could have raced with io_destroy() and are currently holding a
+	 * reference to ctx which should be destroyed. We cannot submit IO
+	 * since ctx gets freed as soon as io_submit() puts its reference.  The
+	 * check here is reliable: io_destroy() sets ctx->dead before waiting
+	 * for outstanding IO and the barrier between these two is realized by
+	 * unlock of mm->ioctx_lock and lock of ctx->ctx_lock.  Analogously we
+	 * increment ctx->reqs_active before checking for ctx->dead and the
+	 * barrier is realized by unlock and lock of ctx->ctx_lock. Thus if we
+	 * don't see ctx->dead set here, io_destroy() waits for our IO to
+	 * finish.
+	 */
+	if (ctx->dead) {
+		spin_unlock_irq(&ctx->ctx_lock);
+		ret = -EINVAL;
+		goto out_put_req;
+	}
+	aio_run_iocb(req);
+	if (!list_empty(&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;
+}
+
+long do_io_submit(aio_context_t ctx_id, long nr,
+		  struct iocb __user *__user *iocbpp, bool compat)
+{
+	struct kioctx *ctx;
+	long ret = 0;
+	int i = 0;
+	struct blk_plug plug;
+	struct kiocb_batch batch;
+
+	if (unlikely(nr < 0))
+		return -EINVAL;
+
+	if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
+		nr = LONG_MAX/sizeof(*iocbpp);
+
+	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;
+	}
+
+	kiocb_batch_init(&batch, nr);
+
+	blk_start_plug(&plug);
+
+	/*
+	 * 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, &batch, compat);
+		if (ret)
+			break;
+	}
+	blk_finish_plug(&plug);
+
+	kiocb_batch_free(ctx, &batch);
+	put_ioctx(ctx);
+	return i ? i : 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.
+ */
+SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
+		struct iocb __user * __user *, iocbpp)
+{
+	return do_io_submit(ctx_id, nr, iocbpp, 0);
+}
+
+/* lookup_kiocb
+ *	Finds a given iocb for cancellation.
+ */
+static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
+				  u32 key)
+{
+	struct list_head *pos;
+
+	assert_spin_locked(&ctx->ctx_lock);
+
+	/* 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.
+ */
+SYSCALL_DEFINE3(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
+		ret = -EINVAL;
+
+	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. If
+ *	it succeeds, the number of read events is returned. May fail with
+ *	-EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
+ *	out of range, if timeout is out of range.  May fail with -EFAULT
+ *	if any of the memory specified is invalid.  May return 0 or
+ *	< min_nr if the timeout specified by timeout has elapsed
+ *	before sufficient events are available, where timeout == NULL
+ *	specifies an infinite timeout. Note that the timeout pointed to by
+ *	timeout is relative and will be updated if not NULL and the
+ *	operation blocks. Will fail with -ENOSYS if not implemented.
+ */
+SYSCALL_DEFINE5(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))
+			ret = read_events(ioctx, min_nr, nr, events, timeout);
+		put_ioctx(ioctx);
+	}
+
+	asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout);
+	return ret;
+}