Initial import

1 files changed, 1732 insertions, 0 deletions

diff --git a/fs/aio.c b/fs/aio.c
new file mode 100644
index 000000000..480440f47
--- /dev/null
+++ b/fs/aio.c
@@ -0,0 +1,1732 @@
+/*
+ *	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.
+ */
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#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>
+
+#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/percpu.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 <linux/migrate.h>
+#include <linux/ramfs.h>
+#include <linux/percpu-refcount.h>
+#include <linux/mount.h>
+
+#include <asm/kmap_types.h>
+#include <asm/uaccess.h>
+
+#include "internal.h"
+
+#define AIO_RING_MAGIC			0xa10a10a1
+#define AIO_RING_COMPAT_FEATURES	1
+#define AIO_RING_INCOMPAT_FEATURES	0
+struct aio_ring {
+	unsigned	id;	/* kernel internal index number */
+	unsigned	nr;	/* number of io_events */
+	unsigned	head;	/* Written to by userland or under ring_lock
+				 * mutex by aio_read_events_ring(). */
+	unsigned	tail;
+
+	unsigned	magic;
+	unsigned	compat_features;
+	unsigned	incompat_features;
+	unsigned	header_length;	/* size of aio_ring */
+
+
+	struct io_event		io_events[0];
+}; /* 128 bytes + ring size */
+
+#define AIO_RING_PAGES	8
+
+struct kioctx_table {
+	struct rcu_head	rcu;
+	unsigned	nr;
+	struct kioctx	*table[];
+};
+
+struct kioctx_cpu {
+	unsigned		reqs_available;
+};
+
+struct ctx_rq_wait {
+	struct completion comp;
+	atomic_t count;
+};
+
+struct kioctx {
+	struct percpu_ref	users;
+	atomic_t		dead;
+
+	struct percpu_ref	reqs;
+
+	unsigned long		user_id;
+
+	struct __percpu kioctx_cpu *cpu;
+
+	/*
+	 * For percpu reqs_available, number of slots we move to/from global
+	 * counter at a time:
+	 */
+	unsigned		req_batch;
+	/*
+	 * This is what userspace passed to io_setup(), it's not used for
+	 * anything but counting against the global max_reqs quota.
+	 *
+	 * The real limit is nr_events - 1, which will be larger (see
+	 * aio_setup_ring())
+	 */
+	unsigned		max_reqs;
+
+	/* Size of ringbuffer, in units of struct io_event */
+	unsigned		nr_events;
+
+	unsigned long		mmap_base;
+	unsigned long		mmap_size;
+
+	struct page		**ring_pages;
+	long			nr_pages;
+
+	struct work_struct	free_work;
+
+	/*
+	 * signals when all in-flight requests are done
+	 */
+	struct ctx_rq_wait	*rq_wait;
+
+	struct {
+		/*
+		 * This counts the number of available slots in the ringbuffer,
+		 * so we avoid overflowing it: it's decremented (if positive)
+		 * when allocating a kiocb and incremented when the resulting
+		 * io_event is pulled off the ringbuffer.
+		 *
+		 * We batch accesses to it with a percpu version.
+		 */
+		atomic_t	reqs_available;
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		spinlock_t	ctx_lock;
+		struct list_head active_reqs;	/* used for cancellation */
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		struct mutex	ring_lock;
+		wait_queue_head_t wait;
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		unsigned	tail;
+		unsigned	completed_events;
+		spinlock_t	completion_lock;
+	} ____cacheline_aligned_in_smp;
+
+	struct page		*internal_pages[AIO_RING_PAGES];
+	struct file		*aio_ring_file;
+
+	unsigned		id;
+};
+
+/*
+ * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
+ * cancelled or completed (this makes a certain amount of sense because
+ * successful cancellation - io_cancel() - does deliver the completion to
+ * userspace).
+ *
+ * And since most things don't implement kiocb cancellation and we'd really like
+ * kiocb completion to be lockless when possible, we use ki_cancel to
+ * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED
+ * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel().
+ */
+#define KIOCB_CANCELLED		((void *) (~0ULL))
+
+struct aio_kiocb {
+	struct kiocb		common;
+
+	struct kioctx		*ki_ctx;
+	kiocb_cancel_fn		*ki_cancel;
+
+	struct iocb __user	*ki_user_iocb;	/* user's aiocb */
+	__u64			ki_user_data;	/* user's data for completion */
+
+	struct list_head	ki_list;	/* the aio core uses this
+						 * for cancellation */
+
+	/*
+	 * If the aio_resfd field of the userspace iocb is not zero,
+	 * this is the underlying eventfd context to deliver events to.
+	 */
+	struct eventfd_ctx	*ki_eventfd;
+};
+
+/*------ 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 vfsmount *aio_mnt;
+
+static const struct file_operations aio_ring_fops;
+static const struct address_space_operations aio_ctx_aops;
+
+static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
+{
+	struct qstr this = QSTR_INIT("[aio]", 5);
+	struct file *file;
+	struct path path;
+	struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+
+	inode->i_mapping->a_ops = &aio_ctx_aops;
+	inode->i_mapping->private_data = ctx;
+	inode->i_size = PAGE_SIZE * nr_pages;
+
+	path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this);
+	if (!path.dentry) {
+		iput(inode);
+		return ERR_PTR(-ENOMEM);
+	}
+	path.mnt = mntget(aio_mnt);
+
+	d_instantiate(path.dentry, inode);
+	file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops);
+	if (IS_ERR(file)) {
+		path_put(&path);
+		return file;
+	}
+
+	file->f_flags = O_RDWR;
+	return file;
+}
+
+static struct dentry *aio_mount(struct file_system_type *fs_type,
+				int flags, const char *dev_name, void *data)
+{
+	static const struct dentry_operations ops = {
+		.d_dname	= simple_dname,
+	};
+	return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC);
+}
+
+/* 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)
+{
+	static struct file_system_type aio_fs = {
+		.name		= "aio",
+		.mount		= aio_mount,
+		.kill_sb	= kill_anon_super,
+	};
+	aio_mnt = kern_mount(&aio_fs);
+	if (IS_ERR(aio_mnt))
+		panic("Failed to create aio fs mount.");
+
+	kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
+	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
+
+	pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
+
+	return 0;
+}
+__initcall(aio_setup);
+
+static void put_aio_ring_file(struct kioctx *ctx)
+{
+	struct file *aio_ring_file = ctx->aio_ring_file;
+	if (aio_ring_file) {
+		truncate_setsize(aio_ring_file->f_inode, 0);
+
+		/* Prevent further access to the kioctx from migratepages */
+		spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock);
+		aio_ring_file->f_inode->i_mapping->private_data = NULL;
+		ctx->aio_ring_file = NULL;
+		spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock);
+
+		fput(aio_ring_file);
+	}
+}
+
+static void aio_free_ring(struct kioctx *ctx)
+{
+	int i;
+
+	/* Disconnect the kiotx from the ring file.  This prevents future
+	 * accesses to the kioctx from page migration.
+	 */
+	put_aio_ring_file(ctx);
+
+	for (i = 0; i < ctx->nr_pages; i++) {
+		struct page *page;
+		pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
+				page_count(ctx->ring_pages[i]));
+		page = ctx->ring_pages[i];
+		if (!page)
+			continue;
+		ctx->ring_pages[i] = NULL;
+		put_page(page);
+	}
+
+	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
+		kfree(ctx->ring_pages);
+		ctx->ring_pages = NULL;
+	}
+}
+
+static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	vma->vm_flags |= VM_DONTEXPAND;
+	vma->vm_ops = &generic_file_vm_ops;
+	return 0;
+}
+
+static int aio_ring_remap(struct file *file, struct vm_area_struct *vma)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct kioctx_table *table;
+	int i, res = -EINVAL;
+
+	spin_lock(&mm->ioctx_lock);
+	rcu_read_lock();
+	table = rcu_dereference(mm->ioctx_table);
+	for (i = 0; i < table->nr; i++) {
+		struct kioctx *ctx;
+
+		ctx = table->table[i];
+		if (ctx && ctx->aio_ring_file == file) {
+			if (!atomic_read(&ctx->dead)) {
+				ctx->user_id = ctx->mmap_base = vma->vm_start;
+				res = 0;
+			}
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+	spin_unlock(&mm->ioctx_lock);
+	return res;
+}
+
+static const struct file_operations aio_ring_fops = {
+	.mmap = aio_ring_mmap,
+	.mremap = aio_ring_remap,
+};
+
+#if IS_ENABLED(CONFIG_MIGRATION)
+static int aio_migratepage(struct address_space *mapping, struct page *new,
+			struct page *old, enum migrate_mode mode)
+{
+	struct kioctx *ctx;
+	unsigned long flags;
+	pgoff_t idx;
+	int rc;
+
+	rc = 0;
+
+	/* mapping->private_lock here protects against the kioctx teardown.  */
+	spin_lock(&mapping->private_lock);
+	ctx = mapping->private_data;
+	if (!ctx) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* The ring_lock mutex.  The prevents aio_read_events() from writing
+	 * to the ring's head, and prevents page migration from mucking in
+	 * a partially initialized kiotx.
+	 */
+	if (!mutex_trylock(&ctx->ring_lock)) {
+		rc = -EAGAIN;
+		goto out;
+	}
+
+	idx = old->index;
+	if (idx < (pgoff_t)ctx->nr_pages) {
+		/* Make sure the old page hasn't already been changed */
+		if (ctx->ring_pages[idx] != old)
+			rc = -EAGAIN;
+	} else
+		rc = -EINVAL;
+
+	if (rc != 0)
+		goto out_unlock;
+
+	/* Writeback must be complete */
+	BUG_ON(PageWriteback(old));
+	get_page(new);
+
+	rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1);
+	if (rc != MIGRATEPAGE_SUCCESS) {
+		put_page(new);
+		goto out_unlock;
+	}
+
+	/* Take completion_lock to prevent other writes to the ring buffer
+	 * while the old page is copied to the new.  This prevents new
+	 * events from being lost.
+	 */
+	spin_lock_irqsave(&ctx->completion_lock, flags);
+	migrate_page_copy(new, old);
+	BUG_ON(ctx->ring_pages[idx] != old);
+	ctx->ring_pages[idx] = new;
+	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+	/* The old page is no longer accessible. */
+	put_page(old);
+
+out_unlock:
+	mutex_unlock(&ctx->ring_lock);
+out:
+	spin_unlock(&mapping->private_lock);
+	return rc;
+}
+#endif
+
+static const struct address_space_operations aio_ctx_aops = {
+	.set_page_dirty = __set_page_dirty_no_writeback,
+#if IS_ENABLED(CONFIG_MIGRATION)
+	.migratepage	= aio_migratepage,
+#endif
+};
+
+static int aio_setup_ring(struct kioctx *ctx)
+{
+	struct aio_ring *ring;
+	unsigned nr_events = ctx->max_reqs;
+	struct mm_struct *mm = current->mm;
+	unsigned long size, unused;
+	int nr_pages;
+	int i;
+	struct file *file;
+
+	/* 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 = PFN_UP(size);
+	if (nr_pages < 0)
+		return -EINVAL;
+
+	file = aio_private_file(ctx, nr_pages);
+	if (IS_ERR(file)) {
+		ctx->aio_ring_file = NULL;
+		return -ENOMEM;
+	}
+
+	ctx->aio_ring_file = file;
+	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
+			/ sizeof(struct io_event);
+
+	ctx->ring_pages = ctx->internal_pages;
+	if (nr_pages > AIO_RING_PAGES) {
+		ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
+					  GFP_KERNEL);
+		if (!ctx->ring_pages) {
+			put_aio_ring_file(ctx);
+			return -ENOMEM;
+		}
+	}
+
+	for (i = 0; i < nr_pages; i++) {
+		struct page *page;
+		page = find_or_create_page(file->f_inode->i_mapping,
+					   i, GFP_HIGHUSER | __GFP_ZERO);
+		if (!page)
+			break;
+		pr_debug("pid(%d) page[%d]->count=%d\n",
+			 current->pid, i, page_count(page));
+		SetPageUptodate(page);
+		unlock_page(page);
+
+		ctx->ring_pages[i] = page;
+	}
+	ctx->nr_pages = i;
+
+	if (unlikely(i != nr_pages)) {
+		aio_free_ring(ctx);
+		return -ENOMEM;
+	}
+
+	ctx->mmap_size = nr_pages * PAGE_SIZE;
+	pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
+
+	down_write(&mm->mmap_sem);
+	ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
+				       PROT_READ | PROT_WRITE,
+				       MAP_SHARED, 0, &unused);
+	up_write(&mm->mmap_sem);
+	if (IS_ERR((void *)ctx->mmap_base)) {
+		ctx->mmap_size = 0;
+		aio_free_ring(ctx);
+		return -ENOMEM;
+	}
+
+	pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
+
+	ctx->user_id = ctx->mmap_base;
+	ctx->nr_events = nr_events; /* trusted copy */
+
+	ring = kmap_atomic(ctx->ring_pages[0]);
+	ring->nr = nr_events;	/* user copy */
+	ring->id = ~0U;
+	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);
+	flush_dcache_page(ctx->ring_pages[0]);
+
+	return 0;
+}
+
+#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)
+
+void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
+{
+	struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common);
+	struct kioctx *ctx = req->ki_ctx;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+
+	if (!req->ki_list.next)
+		list_add(&req->ki_list, &ctx->active_reqs);
+
+	req->ki_cancel = cancel;
+
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+}
+EXPORT_SYMBOL(kiocb_set_cancel_fn);
+
+static int kiocb_cancel(struct aio_kiocb *kiocb)
+{
+	kiocb_cancel_fn *old, *cancel;
+
+	/*
+	 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it
+	 * actually has a cancel function, hence the cmpxchg()
+	 */
+
+	cancel = ACCESS_ONCE(kiocb->ki_cancel);
+	do {
+		if (!cancel || cancel == KIOCB_CANCELLED)
+			return -EINVAL;
+
+		old = cancel;
+		cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
+	} while (cancel != old);
+
+	return cancel(&kiocb->common);
+}
+
+static void free_ioctx(struct work_struct *work)
+{
+	struct kioctx *ctx = container_of(work, struct kioctx, free_work);
+
+	pr_debug("freeing %p\n", ctx);
+
+	aio_free_ring(ctx);
+	free_percpu(ctx->cpu);
+	percpu_ref_exit(&ctx->reqs);
+	percpu_ref_exit(&ctx->users);
+	kmem_cache_free(kioctx_cachep, ctx);
+}
+
+static void free_ioctx_reqs(struct percpu_ref *ref)
+{
+	struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
+
+	/* At this point we know that there are no any in-flight requests */
+	if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
+		complete(&ctx->rq_wait->comp);
+
+	INIT_WORK(&ctx->free_work, free_ioctx);
+	schedule_work(&ctx->free_work);
+}
+
+/*
+ * When this function runs, the kioctx has been removed from the "hash table"
+ * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
+ * now it's safe to cancel any that need to be.
+ */
+static void free_ioctx_users(struct percpu_ref *ref)
+{
+	struct kioctx *ctx = container_of(ref, struct kioctx, users);
+	struct aio_kiocb *req;
+
+	spin_lock_irq(&ctx->ctx_lock);
+
+	while (!list_empty(&ctx->active_reqs)) {
+		req = list_first_entry(&ctx->active_reqs,
+				       struct aio_kiocb, ki_list);
+
+		list_del_init(&req->ki_list);
+		kiocb_cancel(req);
+	}
+
+	spin_unlock_irq(&ctx->ctx_lock);
+
+	percpu_ref_kill(&ctx->reqs);
+	percpu_ref_put(&ctx->reqs);
+}
+
+static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
+{
+	unsigned i, new_nr;
+	struct kioctx_table *table, *old;
+	struct aio_ring *ring;
+
+	spin_lock(&mm->ioctx_lock);
+	table = rcu_dereference_raw(mm->ioctx_table);
+
+	while (1) {
+		if (table)
+			for (i = 0; i < table->nr; i++)
+				if (!table->table[i]) {
+					ctx->id = i;
+					table->table[i] = ctx;
+					spin_unlock(&mm->ioctx_lock);
+
+					/* While kioctx setup is in progress,
+					 * we are protected from page migration
+					 * changes ring_pages by ->ring_lock.
+					 */
+					ring = kmap_atomic(ctx->ring_pages[0]);
+					ring->id = ctx->id;
+					kunmap_atomic(ring);
+					return 0;
+				}
+
+		new_nr = (table ? table->nr : 1) * 4;
+		spin_unlock(&mm->ioctx_lock);
+
+		table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) *
+				new_nr, GFP_KERNEL);
+		if (!table)
+			return -ENOMEM;
+
+		table->nr = new_nr;
+
+		spin_lock(&mm->ioctx_lock);
+		old = rcu_dereference_raw(mm->ioctx_table);
+
+		if (!old) {
+			rcu_assign_pointer(mm->ioctx_table, table);
+		} else if (table->nr > old->nr) {
+			memcpy(table->table, old->table,
+			       old->nr * sizeof(struct kioctx *));
+
+			rcu_assign_pointer(mm->ioctx_table, table);
+			kfree_rcu(old, rcu);
+		} else {
+			kfree(table);
+			table = old;
+		}
+	}
+}
+
+static void aio_nr_sub(unsigned nr)
+{
+	spin_lock(&aio_nr_lock);
+	if (WARN_ON(aio_nr - nr > aio_nr))
+		aio_nr = 0;
+	else
+		aio_nr -= nr;
+	spin_unlock(&aio_nr_lock);
+}
+
+/* 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 = current->mm;
+	struct kioctx *ctx;
+	int err = -ENOMEM;
+
+	/*
+	 * We keep track of the number of available ringbuffer slots, to prevent
+	 * overflow (reqs_available), and we also use percpu counters for this.
+	 *
+	 * So since up to half the slots might be on other cpu's percpu counters
+	 * and unavailable, double nr_events so userspace sees what they
+	 * expected: additionally, we move req_batch slots to/from percpu
+	 * counters at a time, so make sure that isn't 0:
+	 */
+	nr_events = max(nr_events, num_possible_cpus() * 4);
+	nr_events *= 2;
+
+	/* Prevent overflows */
+	if (nr_events > (0x10000000U / sizeof(struct io_event))) {
+		pr_debug("ENOMEM: nr_events too high\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL))
+		return ERR_PTR(-EAGAIN);
+
+	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	ctx->max_reqs = nr_events;
+
+	spin_lock_init(&ctx->ctx_lock);
+	spin_lock_init(&ctx->completion_lock);
+	mutex_init(&ctx->ring_lock);
+	/* Protect against page migration throughout kiotx setup by keeping
+	 * the ring_lock mutex held until setup is complete. */
+	mutex_lock(&ctx->ring_lock);
+	init_waitqueue_head(&ctx->wait);
+
+	INIT_LIST_HEAD(&ctx->active_reqs);
+
+	if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
+		goto err;
+
+	if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
+		goto err;
+
+	ctx->cpu = alloc_percpu(struct kioctx_cpu);
+	if (!ctx->cpu)
+		goto err;
+
+	err = aio_setup_ring(ctx);
+	if (err < 0)
+		goto err;
+
+	atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
+	ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
+	if (ctx->req_batch < 1)
+		ctx->req_batch = 1;
+
+	/* limit the number of system wide aios */
+	spin_lock(&aio_nr_lock);
+	if (aio_nr + nr_events > (aio_max_nr * 2UL) ||
+	    aio_nr + nr_events < aio_nr) {
+		spin_unlock(&aio_nr_lock);
+		err = -EAGAIN;
+		goto err_ctx;
+	}
+	aio_nr += ctx->max_reqs;
+	spin_unlock(&aio_nr_lock);
+
+	percpu_ref_get(&ctx->users);	/* io_setup() will drop this ref */
+	percpu_ref_get(&ctx->reqs);	/* free_ioctx_users() will drop this */
+
+	err = ioctx_add_table(ctx, mm);
+	if (err)
+		goto err_cleanup;
+
+	/* Release the ring_lock mutex now that all setup is complete. */
+	mutex_unlock(&ctx->ring_lock);
+
+	pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
+		 ctx, ctx->user_id, mm, ctx->nr_events);
+	return ctx;
+
+err_cleanup:
+	aio_nr_sub(ctx->max_reqs);
+err_ctx:
+	atomic_set(&ctx->dead, 1);
+	if (ctx->mmap_size)
+		vm_munmap(ctx->mmap_base, ctx->mmap_size);
+	aio_free_ring(ctx);
+err:
+	mutex_unlock(&ctx->ring_lock);
+	free_percpu(ctx->cpu);
+	percpu_ref_exit(&ctx->reqs);
+	percpu_ref_exit(&ctx->users);
+	kmem_cache_free(kioctx_cachep, ctx);
+	pr_debug("error allocating ioctx %d\n", err);
+	return ERR_PTR(err);
+}
+
+/* kill_ioctx
+ *	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 int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
+		      struct ctx_rq_wait *wait)
+{
+	struct kioctx_table *table;
+
+	spin_lock(&mm->ioctx_lock);
+	if (atomic_xchg(&ctx->dead, 1)) {
+		spin_unlock(&mm->ioctx_lock);
+		return -EINVAL;
+	}
+
+	table = rcu_dereference_raw(mm->ioctx_table);
+	WARN_ON(ctx != table->table[ctx->id]);
+	table->table[ctx->id] = NULL;
+	spin_unlock(&mm->ioctx_lock);
+
+	/* percpu_ref_kill() will do the necessary call_rcu() */
+	wake_up_all(&ctx->wait);
+
+	/*
+	 * It'd be more correct to do this in free_ioctx(), after all
+	 * the outstanding kiocbs have finished - but by then io_destroy
+	 * has already returned, so io_setup() could potentially return
+	 * -EAGAIN with no ioctxs actually in use (as far as userspace
+	 *  could tell).
+	 */
+	aio_nr_sub(ctx->max_reqs);
+
+	if (ctx->mmap_size)
+		vm_munmap(ctx->mmap_base, ctx->mmap_size);
+
+	ctx->rq_wait = wait;
+	percpu_ref_kill(&ctx->users);
+	return 0;
+}
+
+/*
+ * 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.
+ *
+ * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
+ * them.
+ */
+void exit_aio(struct mm_struct *mm)
+{
+	struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
+	struct ctx_rq_wait wait;
+	int i, skipped;
+
+	if (!table)
+		return;
+
+	atomic_set(&wait.count, table->nr);
+	init_completion(&wait.comp);
+
+	skipped = 0;
+	for (i = 0; i < table->nr; ++i) {
+		struct kioctx *ctx = table->table[i];
+
+		if (!ctx) {
+			skipped++;
+			continue;
+		}
+
+		/*
+		 * We don't need to bother with munmap() here - exit_mmap(mm)
+		 * is coming and it'll unmap everything. And we simply can't,
+		 * this is not necessarily our ->mm.
+		 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
+		 * that it needs to unmap the area, just set it to 0.
+		 */
+		ctx->mmap_size = 0;
+		kill_ioctx(mm, ctx, &wait);
+	}
+
+	if (!atomic_sub_and_test(skipped, &wait.count)) {
+		/* Wait until all IO for the context are done. */
+		wait_for_completion(&wait.comp);
+	}
+
+	RCU_INIT_POINTER(mm->ioctx_table, NULL);
+	kfree(table);
+}
+
+static void put_reqs_available(struct kioctx *ctx, unsigned nr)
+{
+	struct kioctx_cpu *kcpu;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	kcpu = this_cpu_ptr(ctx->cpu);
+	kcpu->reqs_available += nr;
+
+	while (kcpu->reqs_available >= ctx->req_batch * 2) {
+		kcpu->reqs_available -= ctx->req_batch;
+		atomic_add(ctx->req_batch, &ctx->reqs_available);
+	}
+
+	local_irq_restore(flags);
+}
+
+static bool get_reqs_available(struct kioctx *ctx)
+{
+	struct kioctx_cpu *kcpu;
+	bool ret = false;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	kcpu = this_cpu_ptr(ctx->cpu);
+	if (!kcpu->reqs_available) {
+		int old, avail = atomic_read(&ctx->reqs_available);
+
+		do {
+			if (avail < ctx->req_batch)
+				goto out;
+
+			old = avail;
+			avail = atomic_cmpxchg(&ctx->reqs_available,
+					       avail, avail - ctx->req_batch);
+		} while (avail != old);
+
+		kcpu->reqs_available += ctx->req_batch;
+	}
+
+	ret = true;
+	kcpu->reqs_available--;
+out:
+	local_irq_restore(flags);
+	return ret;
+}
+
+/* refill_reqs_available
+ *	Updates the reqs_available reference counts used for tracking the
+ *	number of free slots in the completion ring.  This can be called
+ *	from aio_complete() (to optimistically update reqs_available) or
+ *	from aio_get_req() (the we're out of events case).  It must be
+ *	called holding ctx->completion_lock.
+ */
+static void refill_reqs_available(struct kioctx *ctx, unsigned head,
+                                  unsigned tail)
+{
+	unsigned events_in_ring, completed;
+
+	/* Clamp head since userland can write to it. */
+	head %= ctx->nr_events;
+	if (head <= tail)
+		events_in_ring = tail - head;
+	else
+		events_in_ring = ctx->nr_events - (head - tail);
+
+	completed = ctx->completed_events;
+	if (events_in_ring < completed)
+		completed -= events_in_ring;
+	else
+		completed = 0;
+
+	if (!completed)
+		return;
+
+	ctx->completed_events -= completed;
+	put_reqs_available(ctx, completed);
+}
+
+/* user_refill_reqs_available
+ *	Called to refill reqs_available when aio_get_req() encounters an
+ *	out of space in the completion ring.
+ */
+static void user_refill_reqs_available(struct kioctx *ctx)
+{
+	spin_lock_irq(&ctx->completion_lock);
+	if (ctx->completed_events) {
+		struct aio_ring *ring;
+		unsigned head;
+
+		/* Access of ring->head may race with aio_read_events_ring()
+		 * here, but that's okay since whether we read the old version
+		 * or the new version, and either will be valid.  The important
+		 * part is that head cannot pass tail since we prevent
+		 * aio_complete() from updating tail by holding
+		 * ctx->completion_lock.  Even if head is invalid, the check
+		 * against ctx->completed_events below will make sure we do the
+		 * safe/right thing.
+		 */
+		ring = kmap_atomic(ctx->ring_pages[0]);
+		head = ring->head;
+		kunmap_atomic(ring);
+
+		refill_reqs_available(ctx, head, ctx->tail);
+	}
+
+	spin_unlock_irq(&ctx->completion_lock);
+}
+
+/* aio_get_req
+ *	Allocate a slot for an aio request.
+ * Returns NULL if no requests are free.
+ */
+static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
+{
+	struct aio_kiocb *req;
+
+	if (!get_reqs_available(ctx)) {
+		user_refill_reqs_available(ctx);
+		if (!get_reqs_available(ctx))
+			return NULL;
+	}
+
+	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO);
+	if (unlikely(!req))
+		goto out_put;
+
+	percpu_ref_get(&ctx->reqs);
+
+	req->ki_ctx = ctx;
+	return req;
+out_put:
+	put_reqs_available(ctx, 1);
+	return NULL;
+}
+
+static void kiocb_free(struct aio_kiocb *req)
+{
+	if (req->common.ki_filp)
+		fput(req->common.ki_filp);
+	if (req->ki_eventfd != NULL)
+		eventfd_ctx_put(req->ki_eventfd);
+	kmem_cache_free(kiocb_cachep, req);
+}
+
+static struct kioctx *lookup_ioctx(unsigned long ctx_id)
+{
+	struct aio_ring __user *ring  = (void __user *)ctx_id;
+	struct mm_struct *mm = current->mm;
+	struct kioctx *ctx, *ret = NULL;
+	struct kioctx_table *table;
+	unsigned id;
+
+	if (get_user(id, &ring->id))
+		return NULL;
+
+	rcu_read_lock();
+	table = rcu_dereference(mm->ioctx_table);
+
+	if (!table || id >= table->nr)
+		goto out;
+
+	ctx = table->table[id];
+	if (ctx && ctx->user_id == ctx_id) {
+		percpu_ref_get(&ctx->users);
+		ret = ctx;
+	}
+out:
+	rcu_read_unlock();
+	return ret;
+}
+
+/* aio_complete
+ *	Called when the io request on the given iocb is complete.
+ */
+static void aio_complete(struct kiocb *kiocb, long res, long res2)
+{
+	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
+	struct kioctx	*ctx = iocb->ki_ctx;
+	struct aio_ring	*ring;
+	struct io_event	*ev_page, *event;
+	unsigned tail, pos, head;
+	unsigned long	flags;
+
+	/*
+	 * 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
+	 */
+	BUG_ON(is_sync_kiocb(kiocb));
+
+	if (iocb->ki_list.next) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&ctx->ctx_lock, flags);
+		list_del(&iocb->ki_list);
+		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+	}
+
+	/*
+	 * Add a completion event to the ring buffer. Must be done holding
+	 * ctx->completion_lock to prevent other code from messing with the tail
+	 * pointer since we might be called from irq context.
+	 */
+	spin_lock_irqsave(&ctx->completion_lock, flags);
+
+	tail = ctx->tail;
+	pos = tail + AIO_EVENTS_OFFSET;
+
+	if (++tail >= ctx->nr_events)
+		tail = 0;
+
+	ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+	event = ev_page + pos % AIO_EVENTS_PER_PAGE;
+
+	event->obj = (u64)(unsigned long)iocb->ki_user_iocb;
+	event->data = iocb->ki_user_data;
+	event->res = res;
+	event->res2 = res2;
+
+	kunmap_atomic(ev_page);
+	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+
+	pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
+		 ctx, tail, iocb, iocb->ki_user_iocb, 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 */
+
+	ctx->tail = tail;
+
+	ring = kmap_atomic(ctx->ring_pages[0]);
+	head = ring->head;
+	ring->tail = tail;
+	kunmap_atomic(ring);
+	flush_dcache_page(ctx->ring_pages[0]);
+
+	ctx->completed_events++;
+	if (ctx->completed_events > 1)
+		refill_reqs_available(ctx, head, tail);
+	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+	pr_debug("added to ring %p at [%u]\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);
+
+	/* everything turned out well, dispose of the aiocb. */
+	kiocb_free(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);
+
+	percpu_ref_put(&ctx->reqs);
+}
+
+/* aio_read_events_ring
+ *	Pull an event off of the ioctx's event ring.  Returns the number of
+ *	events fetched
+ */
+static long aio_read_events_ring(struct kioctx *ctx,
+				 struct io_event __user *event, long nr)
+{
+	struct aio_ring *ring;
+	unsigned head, tail, pos;
+	long ret = 0;
+	int copy_ret;
+
+	/*
+	 * The mutex can block and wake us up and that will cause
+	 * wait_event_interruptible_hrtimeout() to schedule without sleeping
+	 * and repeat. This should be rare enough that it doesn't cause
+	 * peformance issues. See the comment in read_events() for more detail.
+	 */
+	sched_annotate_sleep();
+	mutex_lock(&ctx->ring_lock);
+
+	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
+	ring = kmap_atomic(ctx->ring_pages[0]);
+	head = ring->head;
+	tail = ring->tail;
+	kunmap_atomic(ring);
+
+	/*
+	 * Ensure that once we've read the current tail pointer, that
+	 * we also see the events that were stored up to the tail.
+	 */
+	smp_rmb();
+
+	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
+
+	if (head == tail)
+		goto out;
+
+	head %= ctx->nr_events;
+	tail %= ctx->nr_events;
+
+	while (ret < nr) {
+		long avail;
+		struct io_event *ev;
+		struct page *page;
+
+		avail = (head <= tail ?  tail : ctx->nr_events) - head;
+		if (head == tail)
+			break;
+
+		avail = min(avail, nr - ret);
+		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE -
+			    ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE));
+
+		pos = head + AIO_EVENTS_OFFSET;
+		page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
+		pos %= AIO_EVENTS_PER_PAGE;
+
+		ev = kmap(page);
+		copy_ret = copy_to_user(event + ret, ev + pos,
+					sizeof(*ev) * avail);
+		kunmap(page);
+
+		if (unlikely(copy_ret)) {
+			ret = -EFAULT;
+			goto out;
+		}
+
+		ret += avail;
+		head += avail;
+		head %= ctx->nr_events;
+	}
+
+	ring = kmap_atomic(ctx->ring_pages[0]);
+	ring->head = head;
+	kunmap_atomic(ring);
+	flush_dcache_page(ctx->ring_pages[0]);
+
+	pr_debug("%li  h%u t%u\n", ret, head, tail);
+out:
+	mutex_unlock(&ctx->ring_lock);
+
+	return ret;
+}
+
+static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
+			    struct io_event __user *event, long *i)
+{
+	long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
+
+	if (ret > 0)
+		*i += ret;
+
+	if (unlikely(atomic_read(&ctx->dead)))
+		ret = -EINVAL;
+
+	if (!*i)
+		*i = ret;
+
+	return ret < 0 || *i >= min_nr;
+}
+
+static long read_events(struct kioctx *ctx, long min_nr, long nr,
+			struct io_event __user *event,
+			struct timespec __user *timeout)
+{
+	ktime_t until = { .tv64 = KTIME_MAX };
+	long ret = 0;
+
+	if (timeout) {
+		struct timespec	ts;
+
+		if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
+			return -EFAULT;
+
+		until = timespec_to_ktime(ts);
+	}
+
+	/*
+	 * Note that aio_read_events() is being called as the conditional - i.e.
+	 * we're calling it after prepare_to_wait() has set task state to
+	 * TASK_INTERRUPTIBLE.
+	 *
+	 * But aio_read_events() can block, and if it blocks it's going to flip
+	 * the task state back to TASK_RUNNING.
+	 *
+	 * This should be ok, provided it doesn't flip the state back to
+	 * TASK_RUNNING and return 0 too much - that causes us to spin. That
+	 * will only happen if the mutex_lock() call blocks, and we then find
+	 * the ringbuffer empty. So in practice we should be ok, but it's
+	 * something to be aware of when touching this code.
+	 */
+	if (until.tv64 == 0)
+		aio_read_events(ctx, min_nr, nr, event, &ret);
+	else
+		wait_event_interruptible_hrtimeout(ctx->wait,
+				aio_read_events(ctx, min_nr, nr, event, &ret),
+				until);
+
+	if (!ret && signal_pending(current))
+		ret = -EINTR;
+
+	return ret;
+}
+
+/* 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: 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)
+			kill_ioctx(current->mm, ioctx, NULL);
+		percpu_ref_put(&ioctx->users);
+	}
+
+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)) {
+		struct ctx_rq_wait wait;
+		int ret;
+
+		init_completion(&wait.comp);
+		atomic_set(&wait.count, 1);
+
+		/* Pass requests_done to kill_ioctx() where it can be set
+		 * in a thread-safe way. If we try to set it here then we have
+		 * a race condition if two io_destroy() called simultaneously.
+		 */
+		ret = kill_ioctx(current->mm, ioctx, &wait);
+		percpu_ref_put(&ioctx->users);
+
+		/* Wait until all IO for the context are done. Otherwise kernel
+		 * keep using user-space buffers even if user thinks the context
+		 * is destroyed.
+		 */
+		if (!ret)
+			wait_for_completion(&wait.comp);
+
+		return ret;
+	}
+	pr_debug("EINVAL: invalid context id\n");
+	return -EINVAL;
+}
+
+typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *);
+
+static int aio_setup_vectored_rw(int rw, char __user *buf, size_t len,
+				 struct iovec **iovec,
+				 bool compat,
+				 struct iov_iter *iter)
+{
+#ifdef CONFIG_COMPAT
+	if (compat)
+		return compat_import_iovec(rw,
+				(struct compat_iovec __user *)buf,
+				len, UIO_FASTIOV, iovec, iter);
+#endif
+	return import_iovec(rw, (struct iovec __user *)buf,
+				len, UIO_FASTIOV, iovec, iter);
+}
+
+/*
+ * aio_run_iocb:
+ *	Performs the initial checks and io submission.
+ */
+static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
+			    char __user *buf, size_t len, bool compat)
+{
+	struct file *file = req->ki_filp;
+	ssize_t ret;
+	int rw;
+	fmode_t mode;
+	rw_iter_op *iter_op;
+	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct iov_iter iter;
+
+	switch (opcode) {
+	case IOCB_CMD_PREAD:
+	case IOCB_CMD_PREADV:
+		mode	= FMODE_READ;
+		rw	= READ;
+		iter_op	= file->f_op->read_iter;
+		goto rw_common;
+
+	case IOCB_CMD_PWRITE:
+	case IOCB_CMD_PWRITEV:
+		mode	= FMODE_WRITE;
+		rw	= WRITE;
+		iter_op	= file->f_op->write_iter;
+		goto rw_common;
+rw_common:
+		if (unlikely(!(file->f_mode & mode)))
+			return -EBADF;
+
+		if (!iter_op)
+			return -EINVAL;
+
+		if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV)
+			ret = aio_setup_vectored_rw(rw, buf, len,
+						&iovec, compat, &iter);
+		else {
+			ret = import_single_range(rw, buf, len, iovec, &iter);
+			iovec = NULL;
+		}
+		if (!ret)
+			ret = rw_verify_area(rw, file, &req->ki_pos,
+					     iov_iter_count(&iter));
+		if (ret < 0) {
+			kfree(iovec);
+			return ret;
+		}
+
+		len = ret;
+
+		if (rw == WRITE)
+			file_start_write(file);
+
+		ret = iter_op(req, &iter);
+
+		if (rw == WRITE)
+			file_end_write(file);
+		kfree(iovec);
+		break;
+
+	case IOCB_CMD_FDSYNC:
+		if (!file->f_op->aio_fsync)
+			return -EINVAL;
+
+		ret = file->f_op->aio_fsync(req, 1);
+		break;
+
+	case IOCB_CMD_FSYNC:
+		if (!file->f_op->aio_fsync)
+			return -EINVAL;
+
+		ret = file->f_op->aio_fsync(req, 0);
+		break;
+
+	default:
+		pr_debug("EINVAL: no operation provided\n");
+		return -EINVAL;
+	}
+
+	if (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(req, ret, 0);
+	}
+
+	return 0;
+}
+
+static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
+			 struct iocb *iocb, bool compat)
+{
+	struct aio_kiocb *req;
+	ssize_t ret;
+
+	/* enforce forwards compatibility on users */
+	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
+		pr_debug("EINVAL: 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: overflow check\n");
+		return -EINVAL;
+	}
+
+	req = aio_get_req(ctx);
+	if (unlikely(!req))
+		return -EAGAIN;
+
+	req->common.ki_filp = fget(iocb->aio_fildes);
+	if (unlikely(!req->common.ki_filp)) {
+		ret = -EBADF;
+		goto out_put_req;
+	}
+	req->common.ki_pos = iocb->aio_offset;
+	req->common.ki_complete = aio_complete;
+	req->common.ki_flags = iocb_flags(req->common.ki_filp);
+
+	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;
+		}
+
+		req->common.ki_flags |= IOCB_EVENTFD;
+	}
+
+	ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
+	if (unlikely(ret)) {
+		pr_debug("EFAULT: aio_key\n");
+		goto out_put_req;
+	}
+
+	req->ki_user_iocb = user_iocb;
+	req->ki_user_data = iocb->aio_data;
+
+	ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode,
+			   (char __user *)(unsigned long)iocb->aio_buf,
+			   iocb->aio_nbytes,
+			   compat);
+	if (ret)
+		goto out_put_req;
+
+	return 0;
+out_put_req:
+	put_reqs_available(ctx, 1);
+	percpu_ref_put(&ctx->reqs);
+	kiocb_free(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;
+
+	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: invalid context id\n");
+		return -EINVAL;
+	}
+
+	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, compat);
+		if (ret)
+			break;
+	}
+	blk_finish_plug(&plug);
+
+	percpu_ref_put(&ctx->users);
+	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 aio_kiocb *
+lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key)
+{
+	struct aio_kiocb *kiocb;
+
+	assert_spin_locked(&ctx->ctx_lock);
+
+	if (key != KIOCB_KEY)
+		return NULL;
+
+	/* TODO: use a hash or array, this sucks. */
+	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
+		if (kiocb->ki_user_iocb == iocb)
+			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)
+{
+	struct kioctx *ctx;
+	struct aio_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);
+
+	kiocb = lookup_kiocb(ctx, iocb, key);
+	if (kiocb)
+		ret = kiocb_cancel(kiocb);
+	else
+		ret = -EINVAL;
+
+	spin_unlock_irq(&ctx->ctx_lock);
+
+	if (!ret) {
+		/*
+		 * The result argument is no longer used - the io_event is
+		 * always delivered via the ring buffer. -EINPROGRESS indicates
+		 * cancellation is progress:
+		 */
+		ret = -EINPROGRESS;
+	}
+
+	percpu_ref_put(&ctx->users);
+
+	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.  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);
+		percpu_ref_put(&ioctx->users);
+	}
+	return ret;
+}