Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2416 insertions, 0 deletions

diff --git a/fs/aio.c b/fs/aio.c
new file mode 100644
index 000000000..e85ba0b77
--- /dev/null
+++ b/fs/aio.c
@@ -0,0 +1,2416 @@
+/*
+ *	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.
+ *	Copyright 2018 Christoph Hellwig.
+ *
+ *	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/refcount.h>
+#include <linux/uio.h>
+
+#include <linux/sched/signal.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/mman.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 <linux/pseudo_fs.h>
+
+#include <linux/uaccess.h>
+#include <linux/nospec.h>
+
+#include "internal.h"
+
+#define KIOCB_KEY		0
+
+#define AIO_RING_MAGIC			0xa10a10a1
+#define AIO_RING_COMPAT_FEATURES	1
+#define AIO_RING_INCOMPAT_FEATURES	0
+struct aio_ring {
+	unsigned	id;	/* kernel internal index number */
+	unsigned	nr;	/* number of io_events */
+	unsigned	head;	/* 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[];
+}; /* 128 bytes + ring size */
+
+/*
+ * Plugging is meant to work with larger batches of IOs. If we don't
+ * have more than the below, then don't bother setting up a plug.
+ */
+#define AIO_PLUG_THRESHOLD	2
+
+#define AIO_RING_PAGES	8
+
+struct kioctx_table {
+	struct rcu_head		rcu;
+	unsigned		nr;
+	struct kioctx __rcu	*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 rcu_work		free_rwork;	/* see free_ioctx() */
+
+	/*
+	 * 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;
+};
+
+/*
+ * First field must be the file pointer in all the
+ * iocb unions! See also 'struct kiocb' in <linux/fs.h>
+ */
+struct fsync_iocb {
+	struct file		*file;
+	struct work_struct	work;
+	bool			datasync;
+	struct cred		*creds;
+};
+
+struct poll_iocb {
+	struct file		*file;
+	struct wait_queue_head	*head;
+	__poll_t		events;
+	bool			cancelled;
+	bool			work_scheduled;
+	bool			work_need_resched;
+	struct wait_queue_entry	wait;
+	struct work_struct	work;
+};
+
+/*
+ * NOTE! Each of the iocb union members has the file pointer
+ * as the first entry in their struct definition. So you can
+ * access the file pointer through any of the sub-structs,
+ * or directly as just 'ki_filp' in this struct.
+ */
+struct aio_kiocb {
+	union {
+		struct file		*ki_filp;
+		struct kiocb		rw;
+		struct fsync_iocb	fsync;
+		struct poll_iocb	poll;
+	};
+
+	struct kioctx		*ki_ctx;
+	kiocb_cancel_fn		*ki_cancel;
+
+	struct io_event		ki_res;
+
+	struct list_head	ki_list;	/* the aio core uses this
+						 * for cancellation */
+	refcount_t		ki_refcnt;
+
+	/*
+	 * 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);
+static unsigned long aio_nr;		/* current system wide number of aio requests */
+static unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
+/*----end sysctl variables---*/
+#ifdef CONFIG_SYSCTL
+static struct ctl_table aio_sysctls[] = {
+	{
+		.procname	= "aio-nr",
+		.data		= &aio_nr,
+		.maxlen		= sizeof(aio_nr),
+		.mode		= 0444,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{
+		.procname	= "aio-max-nr",
+		.data		= &aio_max_nr,
+		.maxlen		= sizeof(aio_max_nr),
+		.mode		= 0644,
+		.proc_handler	= proc_doulongvec_minmax,
+	},
+	{}
+};
+
+static void __init aio_sysctl_init(void)
+{
+	register_sysctl_init("fs", aio_sysctls);
+}
+#else
+#define aio_sysctl_init() do { } while (0)
+#endif
+
+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 file *file;
+	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;
+
+	file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
+				O_RDWR, &aio_ring_fops);
+	if (IS_ERR(file))
+		iput(inode);
+	return file;
+}
+
+static int aio_init_fs_context(struct fs_context *fc)
+{
+	if (!init_pseudo(fc, AIO_RING_MAGIC))
+		return -ENOMEM;
+	fc->s_iflags |= SB_I_NOEXEC;
+	return 0;
+}
+
+/* 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",
+		.init_fs_context = aio_init_fs_context,
+		.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);
+	aio_sysctl_init();
+	return 0;
+}
+__initcall(aio_setup);
+
+static void put_aio_ring_file(struct kioctx *ctx)
+{
+	struct file *aio_ring_file = ctx->aio_ring_file;
+	struct address_space *i_mapping;
+
+	if (aio_ring_file) {
+		truncate_setsize(file_inode(aio_ring_file), 0);
+
+		/* Prevent further access to the kioctx from migratepages */
+		i_mapping = aio_ring_file->f_mapping;
+		spin_lock(&i_mapping->private_lock);
+		i_mapping->private_data = NULL;
+		ctx->aio_ring_file = NULL;
+		spin_unlock(&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_mremap(struct vm_area_struct *vma)
+{
+	struct file *file = vma->vm_file;
+	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);
+	if (!table)
+		goto out_unlock;
+
+	for (i = 0; i < table->nr; i++) {
+		struct kioctx *ctx;
+
+		ctx = rcu_dereference(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;
+		}
+	}
+
+out_unlock:
+	rcu_read_unlock();
+	spin_unlock(&mm->ioctx_lock);
+	return res;
+}
+
+static const struct vm_operations_struct aio_ring_vm_ops = {
+	.mremap		= aio_ring_mremap,
+#if IS_ENABLED(CONFIG_MMU)
+	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
+	.page_mkwrite	= filemap_page_mkwrite,
+#endif
+};
+
+static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	vma->vm_flags |= VM_DONTEXPAND;
+	vma->vm_ops = &aio_ring_vm_ops;
+	return 0;
+}
+
+static const struct file_operations aio_ring_fops = {
+	.mmap = aio_ring_mmap,
+};
+
+#if IS_ENABLED(CONFIG_MIGRATION)
+static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
+			struct folio *src, enum migrate_mode mode)
+{
+	struct kioctx *ctx;
+	unsigned long flags;
+	pgoff_t idx;
+	int rc;
+
+	/*
+	 * We cannot support the _NO_COPY case here, because copy needs to
+	 * happen under the ctx->completion_lock. That does not work with the
+	 * migration workflow of MIGRATE_SYNC_NO_COPY.
+	 */
+	if (mode == MIGRATE_SYNC_NO_COPY)
+		return -EINVAL;
+
+	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 = src->index;
+	if (idx < (pgoff_t)ctx->nr_pages) {
+		/* Make sure the old folio hasn't already been changed */
+		if (ctx->ring_pages[idx] != &src->page)
+			rc = -EAGAIN;
+	} else
+		rc = -EINVAL;
+
+	if (rc != 0)
+		goto out_unlock;
+
+	/* Writeback must be complete */
+	BUG_ON(folio_test_writeback(src));
+	folio_get(dst);
+
+	rc = folio_migrate_mapping(mapping, dst, src, 1);
+	if (rc != MIGRATEPAGE_SUCCESS) {
+		folio_put(dst);
+		goto out_unlock;
+	}
+
+	/* Take completion_lock to prevent other writes to the ring buffer
+	 * while the old folio is copied to the new.  This prevents new
+	 * events from being lost.
+	 */
+	spin_lock_irqsave(&ctx->completion_lock, flags);
+	folio_migrate_copy(dst, src);
+	BUG_ON(ctx->ring_pages[idx] != &src->page);
+	ctx->ring_pages[idx] = &dst->page;
+	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+	/* The old folio is no longer accessible. */
+	folio_put(src);
+
+out_unlock:
+	mutex_unlock(&ctx->ring_lock);
+out:
+	spin_unlock(&mapping->private_lock);
+	return rc;
+}
+#else
+#define aio_migrate_folio NULL
+#endif
+
+static const struct address_space_operations aio_ctx_aops = {
+	.dirty_folio	= noop_dirty_folio,
+	.migrate_folio	= aio_migrate_folio,
+};
+
+static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
+{
+	struct aio_ring *ring;
+	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_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);
+
+	if (mmap_write_lock_killable(mm)) {
+		ctx->mmap_size = 0;
+		aio_free_ring(ctx);
+		return -EINTR;
+	}
+
+	ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
+				 PROT_READ | PROT_WRITE,
+				 MAP_SHARED, 0, &unused, NULL);
+	mmap_write_unlock(mm);
+	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, rw);
+	struct kioctx *ctx = req->ki_ctx;
+	unsigned long flags;
+
+	if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
+		return;
+
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+	list_add_tail(&req->ki_list, &ctx->active_reqs);
+	req->ki_cancel = cancel;
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+}
+EXPORT_SYMBOL(kiocb_set_cancel_fn);
+
+/*
+ * free_ioctx() should be RCU delayed to synchronize against the RCU
+ * protected lookup_ioctx() and also needs process context to call
+ * aio_free_ring().  Use rcu_work.
+ */
+static void free_ioctx(struct work_struct *work)
+{
+	struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
+					  free_rwork);
+	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);
+
+	/* Synchronize against RCU protected table->table[] dereferences */
+	INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
+	queue_rcu_work(system_wq, &ctx->free_rwork);
+}
+
+/*
+ * 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);
+		req->ki_cancel(&req->rw);
+		list_del_init(&req->ki_list);
+	}
+
+	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 (!rcu_access_pointer(table->table[i])) {
+					ctx->id = i;
+					rcu_assign_pointer(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(struct_size(table, table, 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;
+
+	/*
+	 * Store the original nr_events -- what userspace passed to io_setup(),
+	 * for counting against the global limit -- before it changes.
+	 */
+	unsigned int max_reqs = nr_events;
+
+	/*
+	 * 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)max_reqs > aio_max_nr)
+		return ERR_PTR(-EAGAIN);
+
+	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
+	if (!ctx)
+		return ERR_PTR(-ENOMEM);
+
+	ctx->max_reqs = max_reqs;
+
+	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, nr_events);
+	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 + ctx->max_reqs > aio_max_nr ||
+	    aio_nr + ctx->max_reqs < 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 != rcu_access_pointer(table->table[ctx->id]));
+	RCU_INIT_POINTER(table->table[ctx->id], NULL);
+	spin_unlock(&mm->ioctx_lock);
+
+	/* free_ioctx_reqs() will do the necessary RCU synchronization */
+	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 =
+			rcu_dereference_protected(table->table[i], true);
+
+		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 avail = atomic_read(&ctx->reqs_available);
+
+		do {
+			if (avail < ctx->req_batch)
+				goto out;
+		} while (!atomic_try_cmpxchg(&ctx->reqs_available,
+					     &avail, avail - ctx->req_batch));
+
+		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);
+}
+
+static bool get_reqs_available(struct kioctx *ctx)
+{
+	if (__get_reqs_available(ctx))
+		return true;
+	user_refill_reqs_available(ctx);
+	return __get_reqs_available(ctx);
+}
+
+/* aio_get_req
+ *	Allocate a slot for an aio request.
+ * Returns NULL if no requests are free.
+ *
+ * The refcount is initialized to 2 - one for the async op completion,
+ * one for the synchronous code that does this.
+ */
+static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
+{
+	struct aio_kiocb *req;
+
+	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
+	if (unlikely(!req))
+		return NULL;
+
+	if (unlikely(!get_reqs_available(ctx))) {
+		kmem_cache_free(kiocb_cachep, req);
+		return NULL;
+	}
+
+	percpu_ref_get(&ctx->reqs);
+	req->ki_ctx = ctx;
+	INIT_LIST_HEAD(&req->ki_list);
+	refcount_set(&req->ki_refcnt, 2);
+	req->ki_eventfd = NULL;
+	return 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;
+
+	id = array_index_nospec(id, table->nr);
+	ctx = rcu_dereference(table->table[id]);
+	if (ctx && ctx->user_id == ctx_id) {
+		if (percpu_ref_tryget_live(&ctx->users))
+			ret = ctx;
+	}
+out:
+	rcu_read_unlock();
+	return ret;
+}
+
+static inline void iocb_destroy(struct aio_kiocb *iocb)
+{
+	if (iocb->ki_eventfd)
+		eventfd_ctx_put(iocb->ki_eventfd);
+	if (iocb->ki_filp)
+		fput(iocb->ki_filp);
+	percpu_ref_put(&iocb->ki_ctx->reqs);
+	kmem_cache_free(kiocb_cachep, iocb);
+}
+
+/* aio_complete
+ *	Called when the io request on the given iocb is complete.
+ */
+static void aio_complete(struct aio_kiocb *iocb)
+{
+	struct kioctx	*ctx = iocb->ki_ctx;
+	struct aio_ring	*ring;
+	struct io_event	*ev_page, *event;
+	unsigned tail, pos, head;
+	unsigned long	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 = iocb->ki_res;
+
+	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,
+		 (void __user *)(unsigned long)iocb->ki_res.obj,
+		 iocb->ki_res.data, iocb->ki_res.res, iocb->ki_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)
+		eventfd_signal(iocb->ki_eventfd, 1);
+
+	/*
+	 * 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);
+}
+
+static inline void iocb_put(struct aio_kiocb *iocb)
+{
+	if (refcount_dec_and_test(&iocb->ki_refcnt)) {
+		aio_complete(iocb);
+		iocb_destroy(iocb);
+	}
+}
+
+/* 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;
+
+		pos = head + AIO_EVENTS_OFFSET;
+		page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
+		pos %= AIO_EVENTS_PER_PAGE;
+
+		avail = min(avail, nr - ret);
+		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
+
+		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,
+			ktime_t until)
+{
+	long ret = 0;
+
+	/*
+	 * 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 == 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);
+	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;
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
+{
+	struct kioctx *ioctx = NULL;
+	unsigned long ctx;
+	long ret;
+
+	ret = get_user(ctx, ctx32p);
+	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)) {
+		/* truncating is ok because it's a user address */
+		ret = put_user((u32)ioctx->user_id, ctx32p);
+		if (ret)
+			kill_ioctx(current->mm, ioctx, NULL);
+		percpu_ref_put(&ioctx->users);
+	}
+
+out:
+	return ret;
+}
+#endif
+
+/* 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;
+}
+
+static void aio_remove_iocb(struct aio_kiocb *iocb)
+{
+	struct kioctx *ctx = iocb->ki_ctx;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+	list_del(&iocb->ki_list);
+	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+}
+
+static void aio_complete_rw(struct kiocb *kiocb, long res)
+{
+	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
+
+	if (!list_empty_careful(&iocb->ki_list))
+		aio_remove_iocb(iocb);
+
+	if (kiocb->ki_flags & IOCB_WRITE) {
+		struct inode *inode = file_inode(kiocb->ki_filp);
+
+		/*
+		 * Tell lockdep we inherited freeze protection from submission
+		 * thread.
+		 */
+		if (S_ISREG(inode->i_mode))
+			__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+		file_end_write(kiocb->ki_filp);
+	}
+
+	iocb->ki_res.res = res;
+	iocb->ki_res.res2 = 0;
+	iocb_put(iocb);
+}
+
+static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
+{
+	int ret;
+
+	req->ki_complete = aio_complete_rw;
+	req->private = NULL;
+	req->ki_pos = iocb->aio_offset;
+	req->ki_flags = req->ki_filp->f_iocb_flags;
+	if (iocb->aio_flags & IOCB_FLAG_RESFD)
+		req->ki_flags |= IOCB_EVENTFD;
+	if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
+		/*
+		 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
+		 * aio_reqprio is interpreted as an I/O scheduling
+		 * class and priority.
+		 */
+		ret = ioprio_check_cap(iocb->aio_reqprio);
+		if (ret) {
+			pr_debug("aio ioprio check cap error: %d\n", ret);
+			return ret;
+		}
+
+		req->ki_ioprio = iocb->aio_reqprio;
+	} else
+		req->ki_ioprio = get_current_ioprio();
+
+	ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
+	if (unlikely(ret))
+		return ret;
+
+	req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
+	return 0;
+}
+
+static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
+		struct iovec **iovec, bool vectored, bool compat,
+		struct iov_iter *iter)
+{
+	void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
+	size_t len = iocb->aio_nbytes;
+
+	if (!vectored) {
+		ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
+		*iovec = NULL;
+		return ret;
+	}
+
+	return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
+}
+
+static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
+{
+	switch (ret) {
+	case -EIOCBQUEUED:
+		break;
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		/*
+		 * There's no easy way to restart the syscall since other AIO's
+		 * may be already running. Just fail this IO with EINTR.
+		 */
+		ret = -EINTR;
+		fallthrough;
+	default:
+		req->ki_complete(req, ret);
+	}
+}
+
+static int aio_read(struct kiocb *req, const struct iocb *iocb,
+			bool vectored, bool compat)
+{
+	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct iov_iter iter;
+	struct file *file;
+	int ret;
+
+	ret = aio_prep_rw(req, iocb);
+	if (ret)
+		return ret;
+	file = req->ki_filp;
+	if (unlikely(!(file->f_mode & FMODE_READ)))
+		return -EBADF;
+	if (unlikely(!file->f_op->read_iter))
+		return -EINVAL;
+
+	ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
+	if (ret < 0)
+		return ret;
+	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
+	if (!ret)
+		aio_rw_done(req, call_read_iter(file, req, &iter));
+	kfree(iovec);
+	return ret;
+}
+
+static int aio_write(struct kiocb *req, const struct iocb *iocb,
+			 bool vectored, bool compat)
+{
+	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct iov_iter iter;
+	struct file *file;
+	int ret;
+
+	ret = aio_prep_rw(req, iocb);
+	if (ret)
+		return ret;
+	file = req->ki_filp;
+
+	if (unlikely(!(file->f_mode & FMODE_WRITE)))
+		return -EBADF;
+	if (unlikely(!file->f_op->write_iter))
+		return -EINVAL;
+
+	ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
+	if (ret < 0)
+		return ret;
+	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
+	if (!ret) {
+		/*
+		 * Open-code file_start_write here to grab freeze protection,
+		 * which will be released by another thread in
+		 * aio_complete_rw().  Fool lockdep by telling it the lock got
+		 * released so that it doesn't complain about the held lock when
+		 * we return to userspace.
+		 */
+		if (S_ISREG(file_inode(file)->i_mode)) {
+			sb_start_write(file_inode(file)->i_sb);
+			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+		}
+		req->ki_flags |= IOCB_WRITE;
+		aio_rw_done(req, call_write_iter(file, req, &iter));
+	}
+	kfree(iovec);
+	return ret;
+}
+
+static void aio_fsync_work(struct work_struct *work)
+{
+	struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
+	const struct cred *old_cred = override_creds(iocb->fsync.creds);
+
+	iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
+	revert_creds(old_cred);
+	put_cred(iocb->fsync.creds);
+	iocb_put(iocb);
+}
+
+static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
+		     bool datasync)
+{
+	if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
+			iocb->aio_rw_flags))
+		return -EINVAL;
+
+	if (unlikely(!req->file->f_op->fsync))
+		return -EINVAL;
+
+	req->creds = prepare_creds();
+	if (!req->creds)
+		return -ENOMEM;
+
+	req->datasync = datasync;
+	INIT_WORK(&req->work, aio_fsync_work);
+	schedule_work(&req->work);
+	return 0;
+}
+
+static void aio_poll_put_work(struct work_struct *work)
+{
+	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
+	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
+
+	iocb_put(iocb);
+}
+
+/*
+ * Safely lock the waitqueue which the request is on, synchronizing with the
+ * case where the ->poll() provider decides to free its waitqueue early.
+ *
+ * Returns true on success, meaning that req->head->lock was locked, req->wait
+ * is on req->head, and an RCU read lock was taken.  Returns false if the
+ * request was already removed from its waitqueue (which might no longer exist).
+ */
+static bool poll_iocb_lock_wq(struct poll_iocb *req)
+{
+	wait_queue_head_t *head;
+
+	/*
+	 * While we hold the waitqueue lock and the waitqueue is nonempty,
+	 * wake_up_pollfree() will wait for us.  However, taking the waitqueue
+	 * lock in the first place can race with the waitqueue being freed.
+	 *
+	 * We solve this as eventpoll does: by taking advantage of the fact that
+	 * all users of wake_up_pollfree() will RCU-delay the actual free.  If
+	 * we enter rcu_read_lock() and see that the pointer to the queue is
+	 * non-NULL, we can then lock it without the memory being freed out from
+	 * under us, then check whether the request is still on the queue.
+	 *
+	 * Keep holding rcu_read_lock() as long as we hold the queue lock, in
+	 * case the caller deletes the entry from the queue, leaving it empty.
+	 * In that case, only RCU prevents the queue memory from being freed.
+	 */
+	rcu_read_lock();
+	head = smp_load_acquire(&req->head);
+	if (head) {
+		spin_lock(&head->lock);
+		if (!list_empty(&req->wait.entry))
+			return true;
+		spin_unlock(&head->lock);
+	}
+	rcu_read_unlock();
+	return false;
+}
+
+static void poll_iocb_unlock_wq(struct poll_iocb *req)
+{
+	spin_unlock(&req->head->lock);
+	rcu_read_unlock();
+}
+
+static void aio_poll_complete_work(struct work_struct *work)
+{
+	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
+	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
+	struct poll_table_struct pt = { ._key = req->events };
+	struct kioctx *ctx = iocb->ki_ctx;
+	__poll_t mask = 0;
+
+	if (!READ_ONCE(req->cancelled))
+		mask = vfs_poll(req->file, &pt) & req->events;
+
+	/*
+	 * Note that ->ki_cancel callers also delete iocb from active_reqs after
+	 * calling ->ki_cancel.  We need the ctx_lock roundtrip here to
+	 * synchronize with them.  In the cancellation case the list_del_init
+	 * itself is not actually needed, but harmless so we keep it in to
+	 * avoid further branches in the fast path.
+	 */
+	spin_lock_irq(&ctx->ctx_lock);
+	if (poll_iocb_lock_wq(req)) {
+		if (!mask && !READ_ONCE(req->cancelled)) {
+			/*
+			 * The request isn't actually ready to be completed yet.
+			 * Reschedule completion if another wakeup came in.
+			 */
+			if (req->work_need_resched) {
+				schedule_work(&req->work);
+				req->work_need_resched = false;
+			} else {
+				req->work_scheduled = false;
+			}
+			poll_iocb_unlock_wq(req);
+			spin_unlock_irq(&ctx->ctx_lock);
+			return;
+		}
+		list_del_init(&req->wait.entry);
+		poll_iocb_unlock_wq(req);
+	} /* else, POLLFREE has freed the waitqueue, so we must complete */
+	list_del_init(&iocb->ki_list);
+	iocb->ki_res.res = mangle_poll(mask);
+	spin_unlock_irq(&ctx->ctx_lock);
+
+	iocb_put(iocb);
+}
+
+/* assumes we are called with irqs disabled */
+static int aio_poll_cancel(struct kiocb *iocb)
+{
+	struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
+	struct poll_iocb *req = &aiocb->poll;
+
+	if (poll_iocb_lock_wq(req)) {
+		WRITE_ONCE(req->cancelled, true);
+		if (!req->work_scheduled) {
+			schedule_work(&aiocb->poll.work);
+			req->work_scheduled = true;
+		}
+		poll_iocb_unlock_wq(req);
+	} /* else, the request was force-cancelled by POLLFREE already */
+
+	return 0;
+}
+
+static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
+		void *key)
+{
+	struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
+	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
+	__poll_t mask = key_to_poll(key);
+	unsigned long flags;
+
+	/* for instances that support it check for an event match first: */
+	if (mask && !(mask & req->events))
+		return 0;
+
+	/*
+	 * Complete the request inline if possible.  This requires that three
+	 * conditions be met:
+	 *   1. An event mask must have been passed.  If a plain wakeup was done
+	 *	instead, then mask == 0 and we have to call vfs_poll() to get
+	 *	the events, so inline completion isn't possible.
+	 *   2. The completion work must not have already been scheduled.
+	 *   3. ctx_lock must not be busy.  We have to use trylock because we
+	 *	already hold the waitqueue lock, so this inverts the normal
+	 *	locking order.  Use irqsave/irqrestore because not all
+	 *	filesystems (e.g. fuse) call this function with IRQs disabled,
+	 *	yet IRQs have to be disabled before ctx_lock is obtained.
+	 */
+	if (mask && !req->work_scheduled &&
+	    spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
+		struct kioctx *ctx = iocb->ki_ctx;
+
+		list_del_init(&req->wait.entry);
+		list_del(&iocb->ki_list);
+		iocb->ki_res.res = mangle_poll(mask);
+		if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
+			iocb = NULL;
+			INIT_WORK(&req->work, aio_poll_put_work);
+			schedule_work(&req->work);
+		}
+		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
+		if (iocb)
+			iocb_put(iocb);
+	} else {
+		/*
+		 * Schedule the completion work if needed.  If it was already
+		 * scheduled, record that another wakeup came in.
+		 *
+		 * Don't remove the request from the waitqueue here, as it might
+		 * not actually be complete yet (we won't know until vfs_poll()
+		 * is called), and we must not miss any wakeups.  POLLFREE is an
+		 * exception to this; see below.
+		 */
+		if (req->work_scheduled) {
+			req->work_need_resched = true;
+		} else {
+			schedule_work(&req->work);
+			req->work_scheduled = true;
+		}
+
+		/*
+		 * If the waitqueue is being freed early but we can't complete
+		 * the request inline, we have to tear down the request as best
+		 * we can.  That means immediately removing the request from its
+		 * waitqueue and preventing all further accesses to the
+		 * waitqueue via the request.  We also need to schedule the
+		 * completion work (done above).  Also mark the request as
+		 * cancelled, to potentially skip an unneeded call to ->poll().
+		 */
+		if (mask & POLLFREE) {
+			WRITE_ONCE(req->cancelled, true);
+			list_del_init(&req->wait.entry);
+
+			/*
+			 * Careful: this *must* be the last step, since as soon
+			 * as req->head is NULL'ed out, the request can be
+			 * completed and freed, since aio_poll_complete_work()
+			 * will no longer need to take the waitqueue lock.
+			 */
+			smp_store_release(&req->head, NULL);
+		}
+	}
+	return 1;
+}
+
+struct aio_poll_table {
+	struct poll_table_struct	pt;
+	struct aio_kiocb		*iocb;
+	bool				queued;
+	int				error;
+};
+
+static void
+aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
+		struct poll_table_struct *p)
+{
+	struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
+
+	/* multiple wait queues per file are not supported */
+	if (unlikely(pt->queued)) {
+		pt->error = -EINVAL;
+		return;
+	}
+
+	pt->queued = true;
+	pt->error = 0;
+	pt->iocb->poll.head = head;
+	add_wait_queue(head, &pt->iocb->poll.wait);
+}
+
+static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
+{
+	struct kioctx *ctx = aiocb->ki_ctx;
+	struct poll_iocb *req = &aiocb->poll;
+	struct aio_poll_table apt;
+	bool cancel = false;
+	__poll_t mask;
+
+	/* reject any unknown events outside the normal event mask. */
+	if ((u16)iocb->aio_buf != iocb->aio_buf)
+		return -EINVAL;
+	/* reject fields that are not defined for poll */
+	if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
+		return -EINVAL;
+
+	INIT_WORK(&req->work, aio_poll_complete_work);
+	req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
+
+	req->head = NULL;
+	req->cancelled = false;
+	req->work_scheduled = false;
+	req->work_need_resched = false;
+
+	apt.pt._qproc = aio_poll_queue_proc;
+	apt.pt._key = req->events;
+	apt.iocb = aiocb;
+	apt.queued = false;
+	apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
+
+	/* initialized the list so that we can do list_empty checks */
+	INIT_LIST_HEAD(&req->wait.entry);
+	init_waitqueue_func_entry(&req->wait, aio_poll_wake);
+
+	mask = vfs_poll(req->file, &apt.pt) & req->events;
+	spin_lock_irq(&ctx->ctx_lock);
+	if (likely(apt.queued)) {
+		bool on_queue = poll_iocb_lock_wq(req);
+
+		if (!on_queue || req->work_scheduled) {
+			/*
+			 * aio_poll_wake() already either scheduled the async
+			 * completion work, or completed the request inline.
+			 */
+			if (apt.error) /* unsupported case: multiple queues */
+				cancel = true;
+			apt.error = 0;
+			mask = 0;
+		}
+		if (mask || apt.error) {
+			/* Steal to complete synchronously. */
+			list_del_init(&req->wait.entry);
+		} else if (cancel) {
+			/* Cancel if possible (may be too late though). */
+			WRITE_ONCE(req->cancelled, true);
+		} else if (on_queue) {
+			/*
+			 * Actually waiting for an event, so add the request to
+			 * active_reqs so that it can be cancelled if needed.
+			 */
+			list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
+			aiocb->ki_cancel = aio_poll_cancel;
+		}
+		if (on_queue)
+			poll_iocb_unlock_wq(req);
+	}
+	if (mask) { /* no async, we'd stolen it */
+		aiocb->ki_res.res = mangle_poll(mask);
+		apt.error = 0;
+	}
+	spin_unlock_irq(&ctx->ctx_lock);
+	if (mask)
+		iocb_put(aiocb);
+	return apt.error;
+}
+
+static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
+			   struct iocb __user *user_iocb, struct aio_kiocb *req,
+			   bool compat)
+{
+	req->ki_filp = fget(iocb->aio_fildes);
+	if (unlikely(!req->ki_filp))
+		return -EBADF;
+
+	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
+		struct eventfd_ctx *eventfd;
+		/*
+		 * 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.
+		 */
+		eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
+		if (IS_ERR(eventfd))
+			return PTR_ERR(eventfd);
+
+		req->ki_eventfd = eventfd;
+	}
+
+	if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
+		pr_debug("EFAULT: aio_key\n");
+		return -EFAULT;
+	}
+
+	req->ki_res.obj = (u64)(unsigned long)user_iocb;
+	req->ki_res.data = iocb->aio_data;
+	req->ki_res.res = 0;
+	req->ki_res.res2 = 0;
+
+	switch (iocb->aio_lio_opcode) {
+	case IOCB_CMD_PREAD:
+		return aio_read(&req->rw, iocb, false, compat);
+	case IOCB_CMD_PWRITE:
+		return aio_write(&req->rw, iocb, false, compat);
+	case IOCB_CMD_PREADV:
+		return aio_read(&req->rw, iocb, true, compat);
+	case IOCB_CMD_PWRITEV:
+		return aio_write(&req->rw, iocb, true, compat);
+	case IOCB_CMD_FSYNC:
+		return aio_fsync(&req->fsync, iocb, false);
+	case IOCB_CMD_FDSYNC:
+		return aio_fsync(&req->fsync, iocb, true);
+	case IOCB_CMD_POLL:
+		return aio_poll(req, iocb);
+	default:
+		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
+		return -EINVAL;
+	}
+}
+
+static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
+			 bool compat)
+{
+	struct aio_kiocb *req;
+	struct iocb iocb;
+	int err;
+
+	if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
+		return -EFAULT;
+
+	/* enforce forwards compatibility on users */
+	if (unlikely(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;
+
+	err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
+
+	/* Done with the synchronous reference */
+	iocb_put(req);
+
+	/*
+	 * If err is 0, we'd either done aio_complete() ourselves or have
+	 * arranged for that to be done asynchronously.  Anything non-zero
+	 * means that we need to destroy req ourselves.
+	 */
+	if (unlikely(err)) {
+		iocb_destroy(req);
+		put_reqs_available(ctx, 1);
+	}
+	return err;
+}
+
+/* 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)
+{
+	struct kioctx *ctx;
+	long ret = 0;
+	int i = 0;
+	struct blk_plug plug;
+
+	if (unlikely(nr < 0))
+		return -EINVAL;
+
+	ctx = lookup_ioctx(ctx_id);
+	if (unlikely(!ctx)) {
+		pr_debug("EINVAL: invalid context id\n");
+		return -EINVAL;
+	}
+
+	if (nr > ctx->nr_events)
+		nr = ctx->nr_events;
+
+	if (nr > AIO_PLUG_THRESHOLD)
+		blk_start_plug(&plug);
+	for (i = 0; i < nr; i++) {
+		struct iocb __user *user_iocb;
+
+		if (unlikely(get_user(user_iocb, iocbpp + i))) {
+			ret = -EFAULT;
+			break;
+		}
+
+		ret = io_submit_one(ctx, user_iocb, false);
+		if (ret)
+			break;
+	}
+	if (nr > AIO_PLUG_THRESHOLD)
+		blk_finish_plug(&plug);
+
+	percpu_ref_put(&ctx->users);
+	return i ? i : ret;
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
+		       int, nr, compat_uptr_t __user *, iocbpp)
+{
+	struct kioctx *ctx;
+	long ret = 0;
+	int i = 0;
+	struct blk_plug plug;
+
+	if (unlikely(nr < 0))
+		return -EINVAL;
+
+	ctx = lookup_ioctx(ctx_id);
+	if (unlikely(!ctx)) {
+		pr_debug("EINVAL: invalid context id\n");
+		return -EINVAL;
+	}
+
+	if (nr > ctx->nr_events)
+		nr = ctx->nr_events;
+
+	if (nr > AIO_PLUG_THRESHOLD)
+		blk_start_plug(&plug);
+	for (i = 0; i < nr; i++) {
+		compat_uptr_t user_iocb;
+
+		if (unlikely(get_user(user_iocb, iocbpp + i))) {
+			ret = -EFAULT;
+			break;
+		}
+
+		ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
+		if (ret)
+			break;
+	}
+	if (nr > AIO_PLUG_THRESHOLD)
+		blk_finish_plug(&plug);
+
+	percpu_ref_put(&ctx->users);
+	return i ? i : ret;
+}
+#endif
+
+/* 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;
+	int ret = -EINVAL;
+	u32 key;
+	u64 obj = (u64)(unsigned long)iocb;
+
+	if (unlikely(get_user(key, &iocb->aio_key)))
+		return -EFAULT;
+	if (unlikely(key != KIOCB_KEY))
+		return -EINVAL;
+
+	ctx = lookup_ioctx(ctx_id);
+	if (unlikely(!ctx))
+		return -EINVAL;
+
+	spin_lock_irq(&ctx->ctx_lock);
+	/* TODO: use a hash or array, this sucks. */
+	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
+		if (kiocb->ki_res.obj == obj) {
+			ret = kiocb->ki_cancel(&kiocb->rw);
+			list_del_init(&kiocb->ki_list);
+			break;
+		}
+	}
+	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;
+}
+
+static long do_io_getevents(aio_context_t ctx_id,
+		long min_nr,
+		long nr,
+		struct io_event __user *events,
+		struct timespec64 *ts)
+{
+	ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
+	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, until);
+		percpu_ref_put(&ioctx->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.
+ */
+#ifdef CONFIG_64BIT
+
+SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
+		long, min_nr,
+		long, nr,
+		struct io_event __user *, events,
+		struct __kernel_timespec __user *, timeout)
+{
+	struct timespec64	ts;
+	int			ret;
+
+	if (timeout && unlikely(get_timespec64(&ts, timeout)))
+		return -EFAULT;
+
+	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+	if (!ret && signal_pending(current))
+		ret = -EINTR;
+	return ret;
+}
+
+#endif
+
+struct __aio_sigset {
+	const sigset_t __user	*sigmask;
+	size_t		sigsetsize;
+};
+
+SYSCALL_DEFINE6(io_pgetevents,
+		aio_context_t, ctx_id,
+		long, min_nr,
+		long, nr,
+		struct io_event __user *, events,
+		struct __kernel_timespec __user *, timeout,
+		const struct __aio_sigset __user *, usig)
+{
+	struct __aio_sigset	ksig = { NULL, };
+	struct timespec64	ts;
+	bool interrupted;
+	int ret;
+
+	if (timeout && unlikely(get_timespec64(&ts, timeout)))
+		return -EFAULT;
+
+	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+		return -EFAULT;
+
+	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
+	if (ret)
+		return ret;
+
+	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+
+	interrupted = signal_pending(current);
+	restore_saved_sigmask_unless(interrupted);
+	if (interrupted && !ret)
+		ret = -ERESTARTNOHAND;
+
+	return ret;
+}
+
+#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
+
+SYSCALL_DEFINE6(io_pgetevents_time32,
+		aio_context_t, ctx_id,
+		long, min_nr,
+		long, nr,
+		struct io_event __user *, events,
+		struct old_timespec32 __user *, timeout,
+		const struct __aio_sigset __user *, usig)
+{
+	struct __aio_sigset	ksig = { NULL, };
+	struct timespec64	ts;
+	bool interrupted;
+	int ret;
+
+	if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
+		return -EFAULT;
+
+	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+		return -EFAULT;
+
+
+	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
+	if (ret)
+		return ret;
+
+	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+
+	interrupted = signal_pending(current);
+	restore_saved_sigmask_unless(interrupted);
+	if (interrupted && !ret)
+		ret = -ERESTARTNOHAND;
+
+	return ret;
+}
+
+#endif
+
+#if defined(CONFIG_COMPAT_32BIT_TIME)
+
+SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
+		__s32, min_nr,
+		__s32, nr,
+		struct io_event __user *, events,
+		struct old_timespec32 __user *, timeout)
+{
+	struct timespec64 t;
+	int ret;
+
+	if (timeout && get_old_timespec32(&t, timeout))
+		return -EFAULT;
+
+	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+	if (!ret && signal_pending(current))
+		ret = -EINTR;
+	return ret;
+}
+
+#endif
+
+#ifdef CONFIG_COMPAT
+
+struct __compat_aio_sigset {
+	compat_uptr_t		sigmask;
+	compat_size_t		sigsetsize;
+};
+
+#if defined(CONFIG_COMPAT_32BIT_TIME)
+
+COMPAT_SYSCALL_DEFINE6(io_pgetevents,
+		compat_aio_context_t, ctx_id,
+		compat_long_t, min_nr,
+		compat_long_t, nr,
+		struct io_event __user *, events,
+		struct old_timespec32 __user *, timeout,
+		const struct __compat_aio_sigset __user *, usig)
+{
+	struct __compat_aio_sigset ksig = { 0, };
+	struct timespec64 t;
+	bool interrupted;
+	int ret;
+
+	if (timeout && get_old_timespec32(&t, timeout))
+		return -EFAULT;
+
+	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+		return -EFAULT;
+
+	ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
+	if (ret)
+		return ret;
+
+	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+
+	interrupted = signal_pending(current);
+	restore_saved_sigmask_unless(interrupted);
+	if (interrupted && !ret)
+		ret = -ERESTARTNOHAND;
+
+	return ret;
+}
+
+#endif
+
+COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
+		compat_aio_context_t, ctx_id,
+		compat_long_t, min_nr,
+		compat_long_t, nr,
+		struct io_event __user *, events,
+		struct __kernel_timespec __user *, timeout,
+		const struct __compat_aio_sigset __user *, usig)
+{
+	struct __compat_aio_sigset ksig = { 0, };
+	struct timespec64 t;
+	bool interrupted;
+	int ret;
+
+	if (timeout && get_timespec64(&t, timeout))
+		return -EFAULT;
+
+	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+		return -EFAULT;
+
+	ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
+	if (ret)
+		return ret;
+
+	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+
+	interrupted = signal_pending(current);
+	restore_saved_sigmask_unless(interrupted);
+	if (interrupted && !ret)
+		ret = -ERESTARTNOHAND;
+
+	return ret;
+}
+#endif