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 000000000000..d06a266769bc
--- /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);