1/*
   2 *	An async IO implementation for Linux
   3 *	Written by Benjamin LaHaise <bcrl@kvack.org>
   4 *
   5 *	Implements an efficient asynchronous io interface.
   6 *
   7 *	Copyright 2000, 2001, 2002 Red Hat, Inc.  All Rights Reserved.
   8 *	Copyright 2018 Christoph Hellwig.
   9 *
  10 *	See ../COPYING for licensing terms.
  11 */
  12#define pr_fmt(fmt) "%s: " fmt, __func__
  13
  14#include <linux/kernel.h>
  15#include <linux/init.h>
  16#include <linux/errno.h>
  17#include <linux/time.h>
  18#include <linux/aio_abi.h>
  19#include <linux/export.h>
  20#include <linux/syscalls.h>
  21#include <linux/backing-dev.h>
  22#include <linux/refcount.h>
  23#include <linux/uio.h>
  24
  25#include <linux/sched/signal.h>
  26#include <linux/fs.h>
  27#include <linux/file.h>
  28#include <linux/mm.h>
  29#include <linux/mman.h>
  30#include <linux/percpu.h>
  31#include <linux/slab.h>
  32#include <linux/timer.h>
  33#include <linux/aio.h>
  34#include <linux/highmem.h>
  35#include <linux/workqueue.h>
  36#include <linux/security.h>
  37#include <linux/eventfd.h>
  38#include <linux/blkdev.h>
  39#include <linux/compat.h>
  40#include <linux/migrate.h>
  41#include <linux/ramfs.h>
  42#include <linux/percpu-refcount.h>
  43#include <linux/mount.h>
  44#include <linux/pseudo_fs.h>
  45
  46#include <linux/uaccess.h>
  47#include <linux/nospec.h>
  48
  49#include "internal.h"
  50
  51#define KIOCB_KEY		0
  52
  53#define AIO_RING_MAGIC			0xa10a10a1
  54#define AIO_RING_COMPAT_FEATURES	1
  55#define AIO_RING_INCOMPAT_FEATURES	0
  56struct aio_ring {
  57	unsigned	id;	/* kernel internal index number */
  58	unsigned	nr;	/* number of io_events */
  59	unsigned	head;	/* Written to by userland or under ring_lock
  60				 * mutex by aio_read_events_ring(). */
  61	unsigned	tail;
  62
  63	unsigned	magic;
  64	unsigned	compat_features;
  65	unsigned	incompat_features;
  66	unsigned	header_length;	/* size of aio_ring */
  67
  68
  69	struct io_event		io_events[];
  70}; /* 128 bytes + ring size */
  71
  72/*
  73 * Plugging is meant to work with larger batches of IOs. If we don't
  74 * have more than the below, then don't bother setting up a plug.
  75 */
  76#define AIO_PLUG_THRESHOLD	2
  77
  78#define AIO_RING_PAGES	8
  79
  80struct kioctx_table {
  81	struct rcu_head		rcu;
  82	unsigned		nr;
  83	struct kioctx __rcu	*table[];
  84};
  85
  86struct kioctx_cpu {
  87	unsigned		reqs_available;
  88};
  89
  90struct ctx_rq_wait {
  91	struct completion comp;
  92	atomic_t count;
  93};
  94
  95struct kioctx {
  96	struct percpu_ref	users;
  97	atomic_t		dead;
  98
  99	struct percpu_ref	reqs;
 100
 101	unsigned long		user_id;
 102
 103	struct __percpu kioctx_cpu *cpu;
 104
 105	/*
 106	 * For percpu reqs_available, number of slots we move to/from global
 107	 * counter at a time:
 108	 */
 109	unsigned		req_batch;
 110	/*
 111	 * This is what userspace passed to io_setup(), it's not used for
 112	 * anything but counting against the global max_reqs quota.
 113	 *
 114	 * The real limit is nr_events - 1, which will be larger (see
 115	 * aio_setup_ring())
 116	 */
 117	unsigned		max_reqs;
 118
 119	/* Size of ringbuffer, in units of struct io_event */
 120	unsigned		nr_events;
 121
 122	unsigned long		mmap_base;
 123	unsigned long		mmap_size;
 124
 125	struct page		**ring_pages;
 126	long			nr_pages;
 127
 128	struct rcu_work		free_rwork;	/* see free_ioctx() */
 129
 130	/*
 131	 * signals when all in-flight requests are done
 132	 */
 133	struct ctx_rq_wait	*rq_wait;
 134
 135	struct {
 136		/*
 137		 * This counts the number of available slots in the ringbuffer,
 138		 * so we avoid overflowing it: it's decremented (if positive)
 139		 * when allocating a kiocb and incremented when the resulting
 140		 * io_event is pulled off the ringbuffer.
 141		 *
 142		 * We batch accesses to it with a percpu version.
 143		 */
 144		atomic_t	reqs_available;
 145	} ____cacheline_aligned_in_smp;
 146
 147	struct {
 148		spinlock_t	ctx_lock;
 149		struct list_head active_reqs;	/* used for cancellation */
 150	} ____cacheline_aligned_in_smp;
 151
 152	struct {
 153		struct mutex	ring_lock;
 154		wait_queue_head_t wait;
 155	} ____cacheline_aligned_in_smp;
 156
 157	struct {
 158		unsigned	tail;
 159		unsigned	completed_events;
 160		spinlock_t	completion_lock;
 161	} ____cacheline_aligned_in_smp;
 162
 163	struct page		*internal_pages[AIO_RING_PAGES];
 164	struct file		*aio_ring_file;
 165
 166	unsigned		id;
 167};
 168
 169/*
 170 * First field must be the file pointer in all the
 171 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
 172 */
 173struct fsync_iocb {
 174	struct file		*file;
 175	struct work_struct	work;
 176	bool			datasync;
 177	struct cred		*creds;
 178};
 179
 180struct poll_iocb {
 181	struct file		*file;
 182	struct wait_queue_head	*head;
 183	__poll_t		events;
 184	bool			cancelled;
 185	bool			work_scheduled;
 186	bool			work_need_resched;
 187	struct wait_queue_entry	wait;
 188	struct work_struct	work;
 189};
 190
 191/*
 192 * NOTE! Each of the iocb union members has the file pointer
 193 * as the first entry in their struct definition. So you can
 194 * access the file pointer through any of the sub-structs,
 195 * or directly as just 'ki_filp' in this struct.
 196 */
 197struct aio_kiocb {
 198	union {
 199		struct file		*ki_filp;
 200		struct kiocb		rw;
 201		struct fsync_iocb	fsync;
 202		struct poll_iocb	poll;
 203	};
 204
 205	struct kioctx		*ki_ctx;
 206	kiocb_cancel_fn		*ki_cancel;
 207
 208	struct io_event		ki_res;
 209
 210	struct list_head	ki_list;	/* the aio core uses this
 211						 * for cancellation */
 212	refcount_t		ki_refcnt;
 213
 214	/*
 215	 * If the aio_resfd field of the userspace iocb is not zero,
 216	 * this is the underlying eventfd context to deliver events to.
 217	 */
 218	struct eventfd_ctx	*ki_eventfd;
 219};
 220
 221/*------ sysctl variables----*/
 222static DEFINE_SPINLOCK(aio_nr_lock);
 223static unsigned long aio_nr;		/* current system wide number of aio requests */
 224static unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
 225/*----end sysctl variables---*/
 226#ifdef CONFIG_SYSCTL
 227static struct ctl_table aio_sysctls[] = {
 228	{
 229		.procname	= "aio-nr",
 230		.data		= &aio_nr,
 231		.maxlen		= sizeof(aio_nr),
 232		.mode		= 0444,
 233		.proc_handler	= proc_doulongvec_minmax,
 234	},
 235	{
 236		.procname	= "aio-max-nr",
 237		.data		= &aio_max_nr,
 238		.maxlen		= sizeof(aio_max_nr),
 239		.mode		= 0644,
 240		.proc_handler	= proc_doulongvec_minmax,
 241	},
 242	{}
 243};
 244
 245static void __init aio_sysctl_init(void)
 246{
 247	register_sysctl_init("fs", aio_sysctls);
 248}
 249#else
 250#define aio_sysctl_init() do { } while (0)
 251#endif
 252
 253static struct kmem_cache	*kiocb_cachep;
 254static struct kmem_cache	*kioctx_cachep;
 255
 256static struct vfsmount *aio_mnt;
 257
 258static const struct file_operations aio_ring_fops;
 259static const struct address_space_operations aio_ctx_aops;
 260
 261static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
 262{
 263	struct file *file;
 264	struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
 265	if (IS_ERR(inode))
 266		return ERR_CAST(inode);
 267
 268	inode->i_mapping->a_ops = &aio_ctx_aops;
 269	inode->i_mapping->private_data = ctx;
 270	inode->i_size = PAGE_SIZE * nr_pages;
 271
 272	file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
 273				O_RDWR, &aio_ring_fops);
 274	if (IS_ERR(file))
 275		iput(inode);
 276	return file;
 277}
 278
 279static int aio_init_fs_context(struct fs_context *fc)
 280{
 281	if (!init_pseudo(fc, AIO_RING_MAGIC))
 282		return -ENOMEM;
 283	fc->s_iflags |= SB_I_NOEXEC;
 284	return 0;
 285}
 286
 287/* aio_setup
 288 *	Creates the slab caches used by the aio routines, panic on
 289 *	failure as this is done early during the boot sequence.
 290 */
 291static int __init aio_setup(void)
 292{
 293	static struct file_system_type aio_fs = {
 294		.name		= "aio",
 295		.init_fs_context = aio_init_fs_context,
 296		.kill_sb	= kill_anon_super,
 297	};
 298	aio_mnt = kern_mount(&aio_fs);
 299	if (IS_ERR(aio_mnt))
 300		panic("Failed to create aio fs mount.");
 301
 302	kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 303	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 304	aio_sysctl_init();
 305	return 0;
 306}
 307__initcall(aio_setup);
 308
 309static void put_aio_ring_file(struct kioctx *ctx)
 310{
 311	struct file *aio_ring_file = ctx->aio_ring_file;
 312	struct address_space *i_mapping;
 313
 314	if (aio_ring_file) {
 315		truncate_setsize(file_inode(aio_ring_file), 0);
 316
 317		/* Prevent further access to the kioctx from migratepages */
 318		i_mapping = aio_ring_file->f_mapping;
 319		spin_lock(&i_mapping->private_lock);
 320		i_mapping->private_data = NULL;
 321		ctx->aio_ring_file = NULL;
 322		spin_unlock(&i_mapping->private_lock);
 323
 324		fput(aio_ring_file);
 325	}
 326}
 327
 328static void aio_free_ring(struct kioctx *ctx)
 329{
 330	int i;
 331
 332	/* Disconnect the kiotx from the ring file.  This prevents future
 333	 * accesses to the kioctx from page migration.
 334	 */
 335	put_aio_ring_file(ctx);
 336
 337	for (i = 0; i < ctx->nr_pages; i++) {
 338		struct page *page;
 339		pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
 340				page_count(ctx->ring_pages[i]));
 341		page = ctx->ring_pages[i];
 342		if (!page)
 343			continue;
 344		ctx->ring_pages[i] = NULL;
 345		put_page(page);
 346	}
 347
 348	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
 349		kfree(ctx->ring_pages);
 350		ctx->ring_pages = NULL;
 351	}
 352}
 353
 354static int aio_ring_mremap(struct vm_area_struct *vma)
 355{
 356	struct file *file = vma->vm_file;
 357	struct mm_struct *mm = vma->vm_mm;
 358	struct kioctx_table *table;
 359	int i, res = -EINVAL;
 360
 361	spin_lock(&mm->ioctx_lock);
 362	rcu_read_lock();
 363	table = rcu_dereference(mm->ioctx_table);
 364	if (!table)
 365		goto out_unlock;
 366
 367	for (i = 0; i < table->nr; i++) {
 368		struct kioctx *ctx;
 369
 370		ctx = rcu_dereference(table->table[i]);
 371		if (ctx && ctx->aio_ring_file == file) {
 372			if (!atomic_read(&ctx->dead)) {
 373				ctx->user_id = ctx->mmap_base = vma->vm_start;
 374				res = 0;
 375			}
 376			break;
 377		}
 378	}
 379
 380out_unlock:
 381	rcu_read_unlock();
 382	spin_unlock(&mm->ioctx_lock);
 383	return res;
 384}
 385
 386static const struct vm_operations_struct aio_ring_vm_ops = {
 387	.mremap		= aio_ring_mremap,
 388#if IS_ENABLED(CONFIG_MMU)
 389	.fault		= filemap_fault,
 390	.map_pages	= filemap_map_pages,
 391	.page_mkwrite	= filemap_page_mkwrite,
 392#endif
 393};
 394
 395static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
 396{
 397	vma->vm_flags |= VM_DONTEXPAND;
 398	vma->vm_ops = &aio_ring_vm_ops;
 399	return 0;
 400}
 401
 402static const struct file_operations aio_ring_fops = {
 403	.mmap = aio_ring_mmap,
 404};
 405
 406#if IS_ENABLED(CONFIG_MIGRATION)
 407static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
 408			struct folio *src, enum migrate_mode mode)
 409{
 410	struct kioctx *ctx;
 411	unsigned long flags;
 412	pgoff_t idx;
 413	int rc;
 414
 415	/*
 416	 * We cannot support the _NO_COPY case here, because copy needs to
 417	 * happen under the ctx->completion_lock. That does not work with the
 418	 * migration workflow of MIGRATE_SYNC_NO_COPY.
 419	 */
 420	if (mode == MIGRATE_SYNC_NO_COPY)
 421		return -EINVAL;
 422
 423	rc = 0;
 424
 425	/* mapping->private_lock here protects against the kioctx teardown.  */
 426	spin_lock(&mapping->private_lock);
 427	ctx = mapping->private_data;
 428	if (!ctx) {
 429		rc = -EINVAL;
 430		goto out;
 431	}
 432
 433	/* The ring_lock mutex.  The prevents aio_read_events() from writing
 434	 * to the ring's head, and prevents page migration from mucking in
 435	 * a partially initialized kiotx.
 436	 */
 437	if (!mutex_trylock(&ctx->ring_lock)) {
 438		rc = -EAGAIN;
 439		goto out;
 440	}
 441
 442	idx = src->index;
 443	if (idx < (pgoff_t)ctx->nr_pages) {
 444		/* Make sure the old folio hasn't already been changed */
 445		if (ctx->ring_pages[idx] != &src->page)
 446			rc = -EAGAIN;
 447	} else
 448		rc = -EINVAL;
 449
 450	if (rc != 0)
 451		goto out_unlock;
 452
 453	/* Writeback must be complete */
 454	BUG_ON(folio_test_writeback(src));
 455	folio_get(dst);
 456
 457	rc = folio_migrate_mapping(mapping, dst, src, 1);
 458	if (rc != MIGRATEPAGE_SUCCESS) {
 459		folio_put(dst);
 460		goto out_unlock;
 461	}
 462
 463	/* Take completion_lock to prevent other writes to the ring buffer
 464	 * while the old folio is copied to the new.  This prevents new
 465	 * events from being lost.
 466	 */
 467	spin_lock_irqsave(&ctx->completion_lock, flags);
 468	folio_migrate_copy(dst, src);
 469	BUG_ON(ctx->ring_pages[idx] != &src->page);
 470	ctx->ring_pages[idx] = &dst->page;
 471	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 472
 473	/* The old folio is no longer accessible. */
 474	folio_put(src);
 475
 476out_unlock:
 477	mutex_unlock(&ctx->ring_lock);
 478out:
 479	spin_unlock(&mapping->private_lock);
 480	return rc;
 481}
 482#else
 483#define aio_migrate_folio NULL
 484#endif
 485
 486static const struct address_space_operations aio_ctx_aops = {
 487	.dirty_folio	= noop_dirty_folio,
 488	.migrate_folio	= aio_migrate_folio,
 489};
 490
 491static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 492{
 493	struct aio_ring *ring;
 494	struct mm_struct *mm = current->mm;
 495	unsigned long size, unused;
 496	int nr_pages;
 497	int i;
 498	struct file *file;
 499
 500	/* Compensate for the ring buffer's head/tail overlap entry */
 501	nr_events += 2;	/* 1 is required, 2 for good luck */
 502
 503	size = sizeof(struct aio_ring);
 504	size += sizeof(struct io_event) * nr_events;
 505
 506	nr_pages = PFN_UP(size);
 507	if (nr_pages < 0)
 508		return -EINVAL;
 509
 510	file = aio_private_file(ctx, nr_pages);
 511	if (IS_ERR(file)) {
 512		ctx->aio_ring_file = NULL;
 513		return -ENOMEM;
 514	}
 515
 516	ctx->aio_ring_file = file;
 517	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
 518			/ sizeof(struct io_event);
 519
 520	ctx->ring_pages = ctx->internal_pages;
 521	if (nr_pages > AIO_RING_PAGES) {
 522		ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
 523					  GFP_KERNEL);
 524		if (!ctx->ring_pages) {
 525			put_aio_ring_file(ctx);
 526			return -ENOMEM;
 527		}
 528	}
 529
 530	for (i = 0; i < nr_pages; i++) {
 531		struct page *page;
 532		page = find_or_create_page(file->f_mapping,
 533					   i, GFP_HIGHUSER | __GFP_ZERO);
 534		if (!page)
 535			break;
 536		pr_debug("pid(%d) page[%d]->count=%d\n",
 537			 current->pid, i, page_count(page));
 538		SetPageUptodate(page);
 539		unlock_page(page);
 540
 541		ctx->ring_pages[i] = page;
 542	}
 543	ctx->nr_pages = i;
 544
 545	if (unlikely(i != nr_pages)) {
 546		aio_free_ring(ctx);
 547		return -ENOMEM;
 548	}
 549
 550	ctx->mmap_size = nr_pages * PAGE_SIZE;
 551	pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
 552
 553	if (mmap_write_lock_killable(mm)) {
 554		ctx->mmap_size = 0;
 555		aio_free_ring(ctx);
 556		return -EINTR;
 557	}
 558
 559	ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
 560				 PROT_READ | PROT_WRITE,
 561				 MAP_SHARED, 0, &unused, NULL);
 562	mmap_write_unlock(mm);
 563	if (IS_ERR((void *)ctx->mmap_base)) {
 564		ctx->mmap_size = 0;
 565		aio_free_ring(ctx);
 566		return -ENOMEM;
 567	}
 568
 569	pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
 570
 571	ctx->user_id = ctx->mmap_base;
 572	ctx->nr_events = nr_events; /* trusted copy */
 573
 574	ring = kmap_atomic(ctx->ring_pages[0]);
 575	ring->nr = nr_events;	/* user copy */
 576	ring->id = ~0U;
 577	ring->head = ring->tail = 0;
 578	ring->magic = AIO_RING_MAGIC;
 579	ring->compat_features = AIO_RING_COMPAT_FEATURES;
 580	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
 581	ring->header_length = sizeof(struct aio_ring);
 582	kunmap_atomic(ring);
 583	flush_dcache_page(ctx->ring_pages[0]);
 584
 585	return 0;
 586}
 587
 588#define AIO_EVENTS_PER_PAGE	(PAGE_SIZE / sizeof(struct io_event))
 589#define AIO_EVENTS_FIRST_PAGE	((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
 590#define AIO_EVENTS_OFFSET	(AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
 591
 592void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
 593{
 594	struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
 595	struct kioctx *ctx = req->ki_ctx;
 596	unsigned long flags;
 597
 
 
 
 
 
 
 
 
 
 598	if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
 599		return;
 600
 
 
 601	spin_lock_irqsave(&ctx->ctx_lock, flags);
 602	list_add_tail(&req->ki_list, &ctx->active_reqs);
 603	req->ki_cancel = cancel;
 604	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
 605}
 606EXPORT_SYMBOL(kiocb_set_cancel_fn);
 607
 608/*
 609 * free_ioctx() should be RCU delayed to synchronize against the RCU
 610 * protected lookup_ioctx() and also needs process context to call
 611 * aio_free_ring().  Use rcu_work.
 612 */
 613static void free_ioctx(struct work_struct *work)
 614{
 615	struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
 616					  free_rwork);
 617	pr_debug("freeing %p\n", ctx);
 618
 619	aio_free_ring(ctx);
 620	free_percpu(ctx->cpu);
 621	percpu_ref_exit(&ctx->reqs);
 622	percpu_ref_exit(&ctx->users);
 623	kmem_cache_free(kioctx_cachep, ctx);
 624}
 625
 626static void free_ioctx_reqs(struct percpu_ref *ref)
 627{
 628	struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
 629
 630	/* At this point we know that there are no any in-flight requests */
 631	if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
 632		complete(&ctx->rq_wait->comp);
 633
 634	/* Synchronize against RCU protected table->table[] dereferences */
 635	INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
 636	queue_rcu_work(system_wq, &ctx->free_rwork);
 637}
 638
 639/*
 640 * When this function runs, the kioctx has been removed from the "hash table"
 641 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
 642 * now it's safe to cancel any that need to be.
 643 */
 644static void free_ioctx_users(struct percpu_ref *ref)
 645{
 646	struct kioctx *ctx = container_of(ref, struct kioctx, users);
 647	struct aio_kiocb *req;
 648
 649	spin_lock_irq(&ctx->ctx_lock);
 650
 651	while (!list_empty(&ctx->active_reqs)) {
 652		req = list_first_entry(&ctx->active_reqs,
 653				       struct aio_kiocb, ki_list);
 654		req->ki_cancel(&req->rw);
 655		list_del_init(&req->ki_list);
 656	}
 657
 658	spin_unlock_irq(&ctx->ctx_lock);
 659
 660	percpu_ref_kill(&ctx->reqs);
 661	percpu_ref_put(&ctx->reqs);
 662}
 663
 664static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
 665{
 666	unsigned i, new_nr;
 667	struct kioctx_table *table, *old;
 668	struct aio_ring *ring;
 669
 670	spin_lock(&mm->ioctx_lock);
 671	table = rcu_dereference_raw(mm->ioctx_table);
 672
 673	while (1) {
 674		if (table)
 675			for (i = 0; i < table->nr; i++)
 676				if (!rcu_access_pointer(table->table[i])) {
 677					ctx->id = i;
 678					rcu_assign_pointer(table->table[i], ctx);
 679					spin_unlock(&mm->ioctx_lock);
 680
 681					/* While kioctx setup is in progress,
 682					 * we are protected from page migration
 683					 * changes ring_pages by ->ring_lock.
 684					 */
 685					ring = kmap_atomic(ctx->ring_pages[0]);
 686					ring->id = ctx->id;
 687					kunmap_atomic(ring);
 688					return 0;
 689				}
 690
 691		new_nr = (table ? table->nr : 1) * 4;
 692		spin_unlock(&mm->ioctx_lock);
 693
 694		table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
 695		if (!table)
 696			return -ENOMEM;
 697
 698		table->nr = new_nr;
 699
 700		spin_lock(&mm->ioctx_lock);
 701		old = rcu_dereference_raw(mm->ioctx_table);
 702
 703		if (!old) {
 704			rcu_assign_pointer(mm->ioctx_table, table);
 705		} else if (table->nr > old->nr) {
 706			memcpy(table->table, old->table,
 707			       old->nr * sizeof(struct kioctx *));
 708
 709			rcu_assign_pointer(mm->ioctx_table, table);
 710			kfree_rcu(old, rcu);
 711		} else {
 712			kfree(table);
 713			table = old;
 714		}
 715	}
 716}
 717
 718static void aio_nr_sub(unsigned nr)
 719{
 720	spin_lock(&aio_nr_lock);
 721	if (WARN_ON(aio_nr - nr > aio_nr))
 722		aio_nr = 0;
 723	else
 724		aio_nr -= nr;
 725	spin_unlock(&aio_nr_lock);
 726}
 727
 728/* ioctx_alloc
 729 *	Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
 730 */
 731static struct kioctx *ioctx_alloc(unsigned nr_events)
 732{
 733	struct mm_struct *mm = current->mm;
 734	struct kioctx *ctx;
 735	int err = -ENOMEM;
 736
 737	/*
 738	 * Store the original nr_events -- what userspace passed to io_setup(),
 739	 * for counting against the global limit -- before it changes.
 740	 */
 741	unsigned int max_reqs = nr_events;
 742
 743	/*
 744	 * We keep track of the number of available ringbuffer slots, to prevent
 745	 * overflow (reqs_available), and we also use percpu counters for this.
 746	 *
 747	 * So since up to half the slots might be on other cpu's percpu counters
 748	 * and unavailable, double nr_events so userspace sees what they
 749	 * expected: additionally, we move req_batch slots to/from percpu
 750	 * counters at a time, so make sure that isn't 0:
 751	 */
 752	nr_events = max(nr_events, num_possible_cpus() * 4);
 753	nr_events *= 2;
 754
 755	/* Prevent overflows */
 756	if (nr_events > (0x10000000U / sizeof(struct io_event))) {
 757		pr_debug("ENOMEM: nr_events too high\n");
 758		return ERR_PTR(-EINVAL);
 759	}
 760
 761	if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
 762		return ERR_PTR(-EAGAIN);
 763
 764	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
 765	if (!ctx)
 766		return ERR_PTR(-ENOMEM);
 767
 768	ctx->max_reqs = max_reqs;
 769
 770	spin_lock_init(&ctx->ctx_lock);
 771	spin_lock_init(&ctx->completion_lock);
 772	mutex_init(&ctx->ring_lock);
 773	/* Protect against page migration throughout kiotx setup by keeping
 774	 * the ring_lock mutex held until setup is complete. */
 775	mutex_lock(&ctx->ring_lock);
 776	init_waitqueue_head(&ctx->wait);
 777
 778	INIT_LIST_HEAD(&ctx->active_reqs);
 779
 780	if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
 781		goto err;
 782
 783	if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
 784		goto err;
 785
 786	ctx->cpu = alloc_percpu(struct kioctx_cpu);
 787	if (!ctx->cpu)
 788		goto err;
 789
 790	err = aio_setup_ring(ctx, nr_events);
 791	if (err < 0)
 792		goto err;
 793
 794	atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
 795	ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
 796	if (ctx->req_batch < 1)
 797		ctx->req_batch = 1;
 798
 799	/* limit the number of system wide aios */
 800	spin_lock(&aio_nr_lock);
 801	if (aio_nr + ctx->max_reqs > aio_max_nr ||
 802	    aio_nr + ctx->max_reqs < aio_nr) {
 803		spin_unlock(&aio_nr_lock);
 804		err = -EAGAIN;
 805		goto err_ctx;
 806	}
 807	aio_nr += ctx->max_reqs;
 808	spin_unlock(&aio_nr_lock);
 809
 810	percpu_ref_get(&ctx->users);	/* io_setup() will drop this ref */
 811	percpu_ref_get(&ctx->reqs);	/* free_ioctx_users() will drop this */
 812
 813	err = ioctx_add_table(ctx, mm);
 814	if (err)
 815		goto err_cleanup;
 816
 817	/* Release the ring_lock mutex now that all setup is complete. */
 818	mutex_unlock(&ctx->ring_lock);
 819
 820	pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
 821		 ctx, ctx->user_id, mm, ctx->nr_events);
 822	return ctx;
 823
 824err_cleanup:
 825	aio_nr_sub(ctx->max_reqs);
 826err_ctx:
 827	atomic_set(&ctx->dead, 1);
 828	if (ctx->mmap_size)
 829		vm_munmap(ctx->mmap_base, ctx->mmap_size);
 830	aio_free_ring(ctx);
 831err:
 832	mutex_unlock(&ctx->ring_lock);
 833	free_percpu(ctx->cpu);
 834	percpu_ref_exit(&ctx->reqs);
 835	percpu_ref_exit(&ctx->users);
 836	kmem_cache_free(kioctx_cachep, ctx);
 837	pr_debug("error allocating ioctx %d\n", err);
 838	return ERR_PTR(err);
 839}
 840
 841/* kill_ioctx
 842 *	Cancels all outstanding aio requests on an aio context.  Used
 843 *	when the processes owning a context have all exited to encourage
 844 *	the rapid destruction of the kioctx.
 845 */
 846static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
 847		      struct ctx_rq_wait *wait)
 848{
 849	struct kioctx_table *table;
 850
 851	spin_lock(&mm->ioctx_lock);
 852	if (atomic_xchg(&ctx->dead, 1)) {
 853		spin_unlock(&mm->ioctx_lock);
 854		return -EINVAL;
 855	}
 856
 857	table = rcu_dereference_raw(mm->ioctx_table);
 858	WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
 859	RCU_INIT_POINTER(table->table[ctx->id], NULL);
 860	spin_unlock(&mm->ioctx_lock);
 861
 862	/* free_ioctx_reqs() will do the necessary RCU synchronization */
 863	wake_up_all(&ctx->wait);
 864
 865	/*
 866	 * It'd be more correct to do this in free_ioctx(), after all
 867	 * the outstanding kiocbs have finished - but by then io_destroy
 868	 * has already returned, so io_setup() could potentially return
 869	 * -EAGAIN with no ioctxs actually in use (as far as userspace
 870	 *  could tell).
 871	 */
 872	aio_nr_sub(ctx->max_reqs);
 873
 874	if (ctx->mmap_size)
 875		vm_munmap(ctx->mmap_base, ctx->mmap_size);
 876
 877	ctx->rq_wait = wait;
 878	percpu_ref_kill(&ctx->users);
 879	return 0;
 880}
 881
 882/*
 883 * exit_aio: called when the last user of mm goes away.  At this point, there is
 884 * no way for any new requests to be submited or any of the io_* syscalls to be
 885 * called on the context.
 886 *
 887 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
 888 * them.
 889 */
 890void exit_aio(struct mm_struct *mm)
 891{
 892	struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
 893	struct ctx_rq_wait wait;
 894	int i, skipped;
 895
 896	if (!table)
 897		return;
 898
 899	atomic_set(&wait.count, table->nr);
 900	init_completion(&wait.comp);
 901
 902	skipped = 0;
 903	for (i = 0; i < table->nr; ++i) {
 904		struct kioctx *ctx =
 905			rcu_dereference_protected(table->table[i], true);
 906
 907		if (!ctx) {
 908			skipped++;
 909			continue;
 910		}
 911
 912		/*
 913		 * We don't need to bother with munmap() here - exit_mmap(mm)
 914		 * is coming and it'll unmap everything. And we simply can't,
 915		 * this is not necessarily our ->mm.
 916		 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
 917		 * that it needs to unmap the area, just set it to 0.
 918		 */
 919		ctx->mmap_size = 0;
 920		kill_ioctx(mm, ctx, &wait);
 921	}
 922
 923	if (!atomic_sub_and_test(skipped, &wait.count)) {
 924		/* Wait until all IO for the context are done. */
 925		wait_for_completion(&wait.comp);
 926	}
 927
 928	RCU_INIT_POINTER(mm->ioctx_table, NULL);
 929	kfree(table);
 930}
 931
 932static void put_reqs_available(struct kioctx *ctx, unsigned nr)
 933{
 934	struct kioctx_cpu *kcpu;
 935	unsigned long flags;
 936
 937	local_irq_save(flags);
 938	kcpu = this_cpu_ptr(ctx->cpu);
 939	kcpu->reqs_available += nr;
 940
 941	while (kcpu->reqs_available >= ctx->req_batch * 2) {
 942		kcpu->reqs_available -= ctx->req_batch;
 943		atomic_add(ctx->req_batch, &ctx->reqs_available);
 944	}
 945
 946	local_irq_restore(flags);
 947}
 948
 949static bool __get_reqs_available(struct kioctx *ctx)
 950{
 951	struct kioctx_cpu *kcpu;
 952	bool ret = false;
 953	unsigned long flags;
 954
 955	local_irq_save(flags);
 956	kcpu = this_cpu_ptr(ctx->cpu);
 957	if (!kcpu->reqs_available) {
 958		int avail = atomic_read(&ctx->reqs_available);
 959
 960		do {
 961			if (avail < ctx->req_batch)
 962				goto out;
 963		} while (!atomic_try_cmpxchg(&ctx->reqs_available,
 964					     &avail, avail - ctx->req_batch));
 965
 966		kcpu->reqs_available += ctx->req_batch;
 967	}
 968
 969	ret = true;
 970	kcpu->reqs_available--;
 971out:
 972	local_irq_restore(flags);
 973	return ret;
 974}
 975
 976/* refill_reqs_available
 977 *	Updates the reqs_available reference counts used for tracking the
 978 *	number of free slots in the completion ring.  This can be called
 979 *	from aio_complete() (to optimistically update reqs_available) or
 980 *	from aio_get_req() (the we're out of events case).  It must be
 981 *	called holding ctx->completion_lock.
 982 */
 983static void refill_reqs_available(struct kioctx *ctx, unsigned head,
 984                                  unsigned tail)
 985{
 986	unsigned events_in_ring, completed;
 987
 988	/* Clamp head since userland can write to it. */
 989	head %= ctx->nr_events;
 990	if (head <= tail)
 991		events_in_ring = tail - head;
 992	else
 993		events_in_ring = ctx->nr_events - (head - tail);
 994
 995	completed = ctx->completed_events;
 996	if (events_in_ring < completed)
 997		completed -= events_in_ring;
 998	else
 999		completed = 0;
1000
1001	if (!completed)
1002		return;
1003
1004	ctx->completed_events -= completed;
1005	put_reqs_available(ctx, completed);
1006}
1007
1008/* user_refill_reqs_available
1009 *	Called to refill reqs_available when aio_get_req() encounters an
1010 *	out of space in the completion ring.
1011 */
1012static void user_refill_reqs_available(struct kioctx *ctx)
1013{
1014	spin_lock_irq(&ctx->completion_lock);
1015	if (ctx->completed_events) {
1016		struct aio_ring *ring;
1017		unsigned head;
1018
1019		/* Access of ring->head may race with aio_read_events_ring()
1020		 * here, but that's okay since whether we read the old version
1021		 * or the new version, and either will be valid.  The important
1022		 * part is that head cannot pass tail since we prevent
1023		 * aio_complete() from updating tail by holding
1024		 * ctx->completion_lock.  Even if head is invalid, the check
1025		 * against ctx->completed_events below will make sure we do the
1026		 * safe/right thing.
1027		 */
1028		ring = kmap_atomic(ctx->ring_pages[0]);
1029		head = ring->head;
1030		kunmap_atomic(ring);
1031
1032		refill_reqs_available(ctx, head, ctx->tail);
1033	}
1034
1035	spin_unlock_irq(&ctx->completion_lock);
1036}
1037
1038static bool get_reqs_available(struct kioctx *ctx)
1039{
1040	if (__get_reqs_available(ctx))
1041		return true;
1042	user_refill_reqs_available(ctx);
1043	return __get_reqs_available(ctx);
1044}
1045
1046/* aio_get_req
1047 *	Allocate a slot for an aio request.
1048 * Returns NULL if no requests are free.
1049 *
1050 * The refcount is initialized to 2 - one for the async op completion,
1051 * one for the synchronous code that does this.
1052 */
1053static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1054{
1055	struct aio_kiocb *req;
1056
1057	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
1058	if (unlikely(!req))
1059		return NULL;
1060
1061	if (unlikely(!get_reqs_available(ctx))) {
1062		kmem_cache_free(kiocb_cachep, req);
1063		return NULL;
1064	}
1065
1066	percpu_ref_get(&ctx->reqs);
1067	req->ki_ctx = ctx;
1068	INIT_LIST_HEAD(&req->ki_list);
1069	refcount_set(&req->ki_refcnt, 2);
1070	req->ki_eventfd = NULL;
1071	return req;
1072}
1073
1074static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1075{
1076	struct aio_ring __user *ring  = (void __user *)ctx_id;
1077	struct mm_struct *mm = current->mm;
1078	struct kioctx *ctx, *ret = NULL;
1079	struct kioctx_table *table;
1080	unsigned id;
1081
1082	if (get_user(id, &ring->id))
1083		return NULL;
1084
1085	rcu_read_lock();
1086	table = rcu_dereference(mm->ioctx_table);
1087
1088	if (!table || id >= table->nr)
1089		goto out;
1090
1091	id = array_index_nospec(id, table->nr);
1092	ctx = rcu_dereference(table->table[id]);
1093	if (ctx && ctx->user_id == ctx_id) {
1094		if (percpu_ref_tryget_live(&ctx->users))
1095			ret = ctx;
1096	}
1097out:
1098	rcu_read_unlock();
1099	return ret;
1100}
1101
1102static inline void iocb_destroy(struct aio_kiocb *iocb)
1103{
1104	if (iocb->ki_eventfd)
1105		eventfd_ctx_put(iocb->ki_eventfd);
1106	if (iocb->ki_filp)
1107		fput(iocb->ki_filp);
1108	percpu_ref_put(&iocb->ki_ctx->reqs);
1109	kmem_cache_free(kiocb_cachep, iocb);
1110}
1111
 
 
 
 
 
1112/* aio_complete
1113 *	Called when the io request on the given iocb is complete.
1114 */
1115static void aio_complete(struct aio_kiocb *iocb)
1116{
1117	struct kioctx	*ctx = iocb->ki_ctx;
1118	struct aio_ring	*ring;
1119	struct io_event	*ev_page, *event;
1120	unsigned tail, pos, head;
1121	unsigned long	flags;
1122
1123	/*
1124	 * Add a completion event to the ring buffer. Must be done holding
1125	 * ctx->completion_lock to prevent other code from messing with the tail
1126	 * pointer since we might be called from irq context.
1127	 */
1128	spin_lock_irqsave(&ctx->completion_lock, flags);
1129
1130	tail = ctx->tail;
1131	pos = tail + AIO_EVENTS_OFFSET;
1132
1133	if (++tail >= ctx->nr_events)
1134		tail = 0;
1135
1136	ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1137	event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1138
1139	*event = iocb->ki_res;
1140
1141	kunmap_atomic(ev_page);
1142	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1143
1144	pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1145		 (void __user *)(unsigned long)iocb->ki_res.obj,
1146		 iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1147
1148	/* after flagging the request as done, we
1149	 * must never even look at it again
1150	 */
1151	smp_wmb();	/* make event visible before updating tail */
1152
1153	ctx->tail = tail;
1154
1155	ring = kmap_atomic(ctx->ring_pages[0]);
1156	head = ring->head;
1157	ring->tail = tail;
1158	kunmap_atomic(ring);
1159	flush_dcache_page(ctx->ring_pages[0]);
1160
1161	ctx->completed_events++;
1162	if (ctx->completed_events > 1)
1163		refill_reqs_available(ctx, head, tail);
 
 
 
 
1164	spin_unlock_irqrestore(&ctx->completion_lock, flags);
1165
1166	pr_debug("added to ring %p at [%u]\n", iocb, tail);
1167
1168	/*
1169	 * Check if the user asked us to deliver the result through an
1170	 * eventfd. The eventfd_signal() function is safe to be called
1171	 * from IRQ context.
1172	 */
1173	if (iocb->ki_eventfd)
1174		eventfd_signal(iocb->ki_eventfd, 1);
1175
1176	/*
1177	 * We have to order our ring_info tail store above and test
1178	 * of the wait list below outside the wait lock.  This is
1179	 * like in wake_up_bit() where clearing a bit has to be
1180	 * ordered with the unlocked test.
1181	 */
1182	smp_mb();
1183
1184	if (waitqueue_active(&ctx->wait))
1185		wake_up(&ctx->wait);
 
 
 
 
 
 
 
 
 
 
1186}
1187
1188static inline void iocb_put(struct aio_kiocb *iocb)
1189{
1190	if (refcount_dec_and_test(&iocb->ki_refcnt)) {
1191		aio_complete(iocb);
1192		iocb_destroy(iocb);
1193	}
1194}
1195
1196/* aio_read_events_ring
1197 *	Pull an event off of the ioctx's event ring.  Returns the number of
1198 *	events fetched
1199 */
1200static long aio_read_events_ring(struct kioctx *ctx,
1201				 struct io_event __user *event, long nr)
1202{
1203	struct aio_ring *ring;
1204	unsigned head, tail, pos;
1205	long ret = 0;
1206	int copy_ret;
1207
1208	/*
1209	 * The mutex can block and wake us up and that will cause
1210	 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1211	 * and repeat. This should be rare enough that it doesn't cause
1212	 * peformance issues. See the comment in read_events() for more detail.
1213	 */
1214	sched_annotate_sleep();
1215	mutex_lock(&ctx->ring_lock);
1216
1217	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
1218	ring = kmap_atomic(ctx->ring_pages[0]);
1219	head = ring->head;
1220	tail = ring->tail;
1221	kunmap_atomic(ring);
1222
1223	/*
1224	 * Ensure that once we've read the current tail pointer, that
1225	 * we also see the events that were stored up to the tail.
1226	 */
1227	smp_rmb();
1228
1229	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1230
1231	if (head == tail)
1232		goto out;
1233
1234	head %= ctx->nr_events;
1235	tail %= ctx->nr_events;
1236
1237	while (ret < nr) {
1238		long avail;
1239		struct io_event *ev;
1240		struct page *page;
1241
1242		avail = (head <= tail ?  tail : ctx->nr_events) - head;
1243		if (head == tail)
1244			break;
1245
1246		pos = head + AIO_EVENTS_OFFSET;
1247		page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1248		pos %= AIO_EVENTS_PER_PAGE;
1249
1250		avail = min(avail, nr - ret);
1251		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1252
1253		ev = kmap(page);
1254		copy_ret = copy_to_user(event + ret, ev + pos,
1255					sizeof(*ev) * avail);
1256		kunmap(page);
1257
1258		if (unlikely(copy_ret)) {
1259			ret = -EFAULT;
1260			goto out;
1261		}
1262
1263		ret += avail;
1264		head += avail;
1265		head %= ctx->nr_events;
1266	}
1267
1268	ring = kmap_atomic(ctx->ring_pages[0]);
1269	ring->head = head;
1270	kunmap_atomic(ring);
1271	flush_dcache_page(ctx->ring_pages[0]);
1272
1273	pr_debug("%li  h%u t%u\n", ret, head, tail);
1274out:
1275	mutex_unlock(&ctx->ring_lock);
1276
1277	return ret;
1278}
1279
1280static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1281			    struct io_event __user *event, long *i)
1282{
1283	long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1284
1285	if (ret > 0)
1286		*i += ret;
1287
1288	if (unlikely(atomic_read(&ctx->dead)))
1289		ret = -EINVAL;
1290
1291	if (!*i)
1292		*i = ret;
1293
1294	return ret < 0 || *i >= min_nr;
1295}
1296
1297static long read_events(struct kioctx *ctx, long min_nr, long nr,
1298			struct io_event __user *event,
1299			ktime_t until)
1300{
1301	long ret = 0;
 
 
1302
1303	/*
1304	 * Note that aio_read_events() is being called as the conditional - i.e.
1305	 * we're calling it after prepare_to_wait() has set task state to
1306	 * TASK_INTERRUPTIBLE.
1307	 *
1308	 * But aio_read_events() can block, and if it blocks it's going to flip
1309	 * the task state back to TASK_RUNNING.
1310	 *
1311	 * This should be ok, provided it doesn't flip the state back to
1312	 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1313	 * will only happen if the mutex_lock() call blocks, and we then find
1314	 * the ringbuffer empty. So in practice we should be ok, but it's
1315	 * something to be aware of when touching this code.
1316	 */
1317	if (until == 0)
1318		aio_read_events(ctx, min_nr, nr, event, &ret);
1319	else
1320		wait_event_interruptible_hrtimeout(ctx->wait,
1321				aio_read_events(ctx, min_nr, nr, event, &ret),
1322				until);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1323	return ret;
1324}
1325
1326/* sys_io_setup:
1327 *	Create an aio_context capable of receiving at least nr_events.
1328 *	ctxp must not point to an aio_context that already exists, and
1329 *	must be initialized to 0 prior to the call.  On successful
1330 *	creation of the aio_context, *ctxp is filled in with the resulting 
1331 *	handle.  May fail with -EINVAL if *ctxp is not initialized,
1332 *	if the specified nr_events exceeds internal limits.  May fail 
1333 *	with -EAGAIN if the specified nr_events exceeds the user's limit 
1334 *	of available events.  May fail with -ENOMEM if insufficient kernel
1335 *	resources are available.  May fail with -EFAULT if an invalid
1336 *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
1337 *	implemented.
1338 */
1339SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1340{
1341	struct kioctx *ioctx = NULL;
1342	unsigned long ctx;
1343	long ret;
1344
1345	ret = get_user(ctx, ctxp);
1346	if (unlikely(ret))
1347		goto out;
1348
1349	ret = -EINVAL;
1350	if (unlikely(ctx || nr_events == 0)) {
1351		pr_debug("EINVAL: ctx %lu nr_events %u\n",
1352		         ctx, nr_events);
1353		goto out;
1354	}
1355
1356	ioctx = ioctx_alloc(nr_events);
1357	ret = PTR_ERR(ioctx);
1358	if (!IS_ERR(ioctx)) {
1359		ret = put_user(ioctx->user_id, ctxp);
1360		if (ret)
1361			kill_ioctx(current->mm, ioctx, NULL);
1362		percpu_ref_put(&ioctx->users);
1363	}
1364
1365out:
1366	return ret;
1367}
1368
1369#ifdef CONFIG_COMPAT
1370COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1371{
1372	struct kioctx *ioctx = NULL;
1373	unsigned long ctx;
1374	long ret;
1375
1376	ret = get_user(ctx, ctx32p);
1377	if (unlikely(ret))
1378		goto out;
1379
1380	ret = -EINVAL;
1381	if (unlikely(ctx || nr_events == 0)) {
1382		pr_debug("EINVAL: ctx %lu nr_events %u\n",
1383		         ctx, nr_events);
1384		goto out;
1385	}
1386
1387	ioctx = ioctx_alloc(nr_events);
1388	ret = PTR_ERR(ioctx);
1389	if (!IS_ERR(ioctx)) {
1390		/* truncating is ok because it's a user address */
1391		ret = put_user((u32)ioctx->user_id, ctx32p);
1392		if (ret)
1393			kill_ioctx(current->mm, ioctx, NULL);
1394		percpu_ref_put(&ioctx->users);
1395	}
1396
1397out:
1398	return ret;
1399}
1400#endif
1401
1402/* sys_io_destroy:
1403 *	Destroy the aio_context specified.  May cancel any outstanding 
1404 *	AIOs and block on completion.  Will fail with -ENOSYS if not
1405 *	implemented.  May fail with -EINVAL if the context pointed to
1406 *	is invalid.
1407 */
1408SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1409{
1410	struct kioctx *ioctx = lookup_ioctx(ctx);
1411	if (likely(NULL != ioctx)) {
1412		struct ctx_rq_wait wait;
1413		int ret;
1414
1415		init_completion(&wait.comp);
1416		atomic_set(&wait.count, 1);
1417
1418		/* Pass requests_done to kill_ioctx() where it can be set
1419		 * in a thread-safe way. If we try to set it here then we have
1420		 * a race condition if two io_destroy() called simultaneously.
1421		 */
1422		ret = kill_ioctx(current->mm, ioctx, &wait);
1423		percpu_ref_put(&ioctx->users);
1424
1425		/* Wait until all IO for the context are done. Otherwise kernel
1426		 * keep using user-space buffers even if user thinks the context
1427		 * is destroyed.
1428		 */
1429		if (!ret)
1430			wait_for_completion(&wait.comp);
1431
1432		return ret;
1433	}
1434	pr_debug("EINVAL: invalid context id\n");
1435	return -EINVAL;
1436}
1437
1438static void aio_remove_iocb(struct aio_kiocb *iocb)
1439{
1440	struct kioctx *ctx = iocb->ki_ctx;
1441	unsigned long flags;
1442
1443	spin_lock_irqsave(&ctx->ctx_lock, flags);
1444	list_del(&iocb->ki_list);
1445	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1446}
1447
1448static void aio_complete_rw(struct kiocb *kiocb, long res)
1449{
1450	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1451
1452	if (!list_empty_careful(&iocb->ki_list))
1453		aio_remove_iocb(iocb);
1454
1455	if (kiocb->ki_flags & IOCB_WRITE) {
1456		struct inode *inode = file_inode(kiocb->ki_filp);
1457
1458		/*
1459		 * Tell lockdep we inherited freeze protection from submission
1460		 * thread.
1461		 */
1462		if (S_ISREG(inode->i_mode))
1463			__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
1464		file_end_write(kiocb->ki_filp);
1465	}
1466
1467	iocb->ki_res.res = res;
1468	iocb->ki_res.res2 = 0;
1469	iocb_put(iocb);
1470}
1471
1472static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
1473{
1474	int ret;
1475
1476	req->ki_complete = aio_complete_rw;
1477	req->private = NULL;
1478	req->ki_pos = iocb->aio_offset;
1479	req->ki_flags = req->ki_filp->f_iocb_flags;
1480	if (iocb->aio_flags & IOCB_FLAG_RESFD)
1481		req->ki_flags |= IOCB_EVENTFD;
1482	if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1483		/*
1484		 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1485		 * aio_reqprio is interpreted as an I/O scheduling
1486		 * class and priority.
1487		 */
1488		ret = ioprio_check_cap(iocb->aio_reqprio);
1489		if (ret) {
1490			pr_debug("aio ioprio check cap error: %d\n", ret);
1491			return ret;
1492		}
1493
1494		req->ki_ioprio = iocb->aio_reqprio;
1495	} else
1496		req->ki_ioprio = get_current_ioprio();
1497
1498	ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
1499	if (unlikely(ret))
1500		return ret;
1501
1502	req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1503	return 0;
1504}
1505
1506static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1507		struct iovec **iovec, bool vectored, bool compat,
1508		struct iov_iter *iter)
1509{
1510	void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1511	size_t len = iocb->aio_nbytes;
1512
1513	if (!vectored) {
1514		ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
1515		*iovec = NULL;
1516		return ret;
1517	}
1518
1519	return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
1520}
1521
1522static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1523{
1524	switch (ret) {
1525	case -EIOCBQUEUED:
1526		break;
1527	case -ERESTARTSYS:
1528	case -ERESTARTNOINTR:
1529	case -ERESTARTNOHAND:
1530	case -ERESTART_RESTARTBLOCK:
1531		/*
1532		 * There's no easy way to restart the syscall since other AIO's
1533		 * may be already running. Just fail this IO with EINTR.
1534		 */
1535		ret = -EINTR;
1536		fallthrough;
1537	default:
1538		req->ki_complete(req, ret);
1539	}
1540}
1541
1542static int aio_read(struct kiocb *req, const struct iocb *iocb,
1543			bool vectored, bool compat)
1544{
1545	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1546	struct iov_iter iter;
1547	struct file *file;
1548	int ret;
1549
1550	ret = aio_prep_rw(req, iocb);
1551	if (ret)
1552		return ret;
1553	file = req->ki_filp;
1554	if (unlikely(!(file->f_mode & FMODE_READ)))
1555		return -EBADF;
1556	if (unlikely(!file->f_op->read_iter))
1557		return -EINVAL;
1558
1559	ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
1560	if (ret < 0)
1561		return ret;
1562	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1563	if (!ret)
1564		aio_rw_done(req, call_read_iter(file, req, &iter));
1565	kfree(iovec);
1566	return ret;
1567}
1568
1569static int aio_write(struct kiocb *req, const struct iocb *iocb,
1570			 bool vectored, bool compat)
1571{
1572	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1573	struct iov_iter iter;
1574	struct file *file;
1575	int ret;
1576
1577	ret = aio_prep_rw(req, iocb);
1578	if (ret)
1579		return ret;
1580	file = req->ki_filp;
1581
1582	if (unlikely(!(file->f_mode & FMODE_WRITE)))
1583		return -EBADF;
1584	if (unlikely(!file->f_op->write_iter))
1585		return -EINVAL;
1586
1587	ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
1588	if (ret < 0)
1589		return ret;
1590	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1591	if (!ret) {
1592		/*
1593		 * Open-code file_start_write here to grab freeze protection,
1594		 * which will be released by another thread in
1595		 * aio_complete_rw().  Fool lockdep by telling it the lock got
1596		 * released so that it doesn't complain about the held lock when
1597		 * we return to userspace.
1598		 */
1599		if (S_ISREG(file_inode(file)->i_mode)) {
1600			sb_start_write(file_inode(file)->i_sb);
1601			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
1602		}
1603		req->ki_flags |= IOCB_WRITE;
1604		aio_rw_done(req, call_write_iter(file, req, &iter));
1605	}
1606	kfree(iovec);
1607	return ret;
1608}
1609
1610static void aio_fsync_work(struct work_struct *work)
1611{
1612	struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1613	const struct cred *old_cred = override_creds(iocb->fsync.creds);
1614
1615	iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
1616	revert_creds(old_cred);
1617	put_cred(iocb->fsync.creds);
1618	iocb_put(iocb);
1619}
1620
1621static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1622		     bool datasync)
1623{
1624	if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1625			iocb->aio_rw_flags))
1626		return -EINVAL;
1627
1628	if (unlikely(!req->file->f_op->fsync))
1629		return -EINVAL;
1630
1631	req->creds = prepare_creds();
1632	if (!req->creds)
1633		return -ENOMEM;
1634
1635	req->datasync = datasync;
1636	INIT_WORK(&req->work, aio_fsync_work);
1637	schedule_work(&req->work);
1638	return 0;
1639}
1640
1641static void aio_poll_put_work(struct work_struct *work)
1642{
1643	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1644	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1645
1646	iocb_put(iocb);
1647}
1648
1649/*
1650 * Safely lock the waitqueue which the request is on, synchronizing with the
1651 * case where the ->poll() provider decides to free its waitqueue early.
1652 *
1653 * Returns true on success, meaning that req->head->lock was locked, req->wait
1654 * is on req->head, and an RCU read lock was taken.  Returns false if the
1655 * request was already removed from its waitqueue (which might no longer exist).
1656 */
1657static bool poll_iocb_lock_wq(struct poll_iocb *req)
1658{
1659	wait_queue_head_t *head;
1660
1661	/*
1662	 * While we hold the waitqueue lock and the waitqueue is nonempty,
1663	 * wake_up_pollfree() will wait for us.  However, taking the waitqueue
1664	 * lock in the first place can race with the waitqueue being freed.
1665	 *
1666	 * We solve this as eventpoll does: by taking advantage of the fact that
1667	 * all users of wake_up_pollfree() will RCU-delay the actual free.  If
1668	 * we enter rcu_read_lock() and see that the pointer to the queue is
1669	 * non-NULL, we can then lock it without the memory being freed out from
1670	 * under us, then check whether the request is still on the queue.
1671	 *
1672	 * Keep holding rcu_read_lock() as long as we hold the queue lock, in
1673	 * case the caller deletes the entry from the queue, leaving it empty.
1674	 * In that case, only RCU prevents the queue memory from being freed.
1675	 */
1676	rcu_read_lock();
1677	head = smp_load_acquire(&req->head);
1678	if (head) {
1679		spin_lock(&head->lock);
1680		if (!list_empty(&req->wait.entry))
1681			return true;
1682		spin_unlock(&head->lock);
1683	}
1684	rcu_read_unlock();
1685	return false;
1686}
1687
1688static void poll_iocb_unlock_wq(struct poll_iocb *req)
1689{
1690	spin_unlock(&req->head->lock);
1691	rcu_read_unlock();
1692}
1693
1694static void aio_poll_complete_work(struct work_struct *work)
1695{
1696	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1697	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1698	struct poll_table_struct pt = { ._key = req->events };
1699	struct kioctx *ctx = iocb->ki_ctx;
1700	__poll_t mask = 0;
1701
1702	if (!READ_ONCE(req->cancelled))
1703		mask = vfs_poll(req->file, &pt) & req->events;
1704
1705	/*
1706	 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1707	 * calling ->ki_cancel.  We need the ctx_lock roundtrip here to
1708	 * synchronize with them.  In the cancellation case the list_del_init
1709	 * itself is not actually needed, but harmless so we keep it in to
1710	 * avoid further branches in the fast path.
1711	 */
1712	spin_lock_irq(&ctx->ctx_lock);
1713	if (poll_iocb_lock_wq(req)) {
1714		if (!mask && !READ_ONCE(req->cancelled)) {
1715			/*
1716			 * The request isn't actually ready to be completed yet.
1717			 * Reschedule completion if another wakeup came in.
1718			 */
1719			if (req->work_need_resched) {
1720				schedule_work(&req->work);
1721				req->work_need_resched = false;
1722			} else {
1723				req->work_scheduled = false;
1724			}
1725			poll_iocb_unlock_wq(req);
1726			spin_unlock_irq(&ctx->ctx_lock);
1727			return;
1728		}
1729		list_del_init(&req->wait.entry);
1730		poll_iocb_unlock_wq(req);
1731	} /* else, POLLFREE has freed the waitqueue, so we must complete */
1732	list_del_init(&iocb->ki_list);
1733	iocb->ki_res.res = mangle_poll(mask);
1734	spin_unlock_irq(&ctx->ctx_lock);
1735
1736	iocb_put(iocb);
1737}
1738
1739/* assumes we are called with irqs disabled */
1740static int aio_poll_cancel(struct kiocb *iocb)
1741{
1742	struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1743	struct poll_iocb *req = &aiocb->poll;
1744
1745	if (poll_iocb_lock_wq(req)) {
1746		WRITE_ONCE(req->cancelled, true);
1747		if (!req->work_scheduled) {
1748			schedule_work(&aiocb->poll.work);
1749			req->work_scheduled = true;
1750		}
1751		poll_iocb_unlock_wq(req);
1752	} /* else, the request was force-cancelled by POLLFREE already */
1753
1754	return 0;
1755}
1756
1757static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1758		void *key)
1759{
1760	struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1761	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1762	__poll_t mask = key_to_poll(key);
1763	unsigned long flags;
1764
1765	/* for instances that support it check for an event match first: */
1766	if (mask && !(mask & req->events))
1767		return 0;
1768
1769	/*
1770	 * Complete the request inline if possible.  This requires that three
1771	 * conditions be met:
1772	 *   1. An event mask must have been passed.  If a plain wakeup was done
1773	 *	instead, then mask == 0 and we have to call vfs_poll() to get
1774	 *	the events, so inline completion isn't possible.
1775	 *   2. The completion work must not have already been scheduled.
1776	 *   3. ctx_lock must not be busy.  We have to use trylock because we
1777	 *	already hold the waitqueue lock, so this inverts the normal
1778	 *	locking order.  Use irqsave/irqrestore because not all
1779	 *	filesystems (e.g. fuse) call this function with IRQs disabled,
1780	 *	yet IRQs have to be disabled before ctx_lock is obtained.
1781	 */
1782	if (mask && !req->work_scheduled &&
1783	    spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1784		struct kioctx *ctx = iocb->ki_ctx;
1785
1786		list_del_init(&req->wait.entry);
1787		list_del(&iocb->ki_list);
1788		iocb->ki_res.res = mangle_poll(mask);
1789		if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1790			iocb = NULL;
1791			INIT_WORK(&req->work, aio_poll_put_work);
1792			schedule_work(&req->work);
1793		}
1794		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1795		if (iocb)
1796			iocb_put(iocb);
1797	} else {
1798		/*
1799		 * Schedule the completion work if needed.  If it was already
1800		 * scheduled, record that another wakeup came in.
1801		 *
1802		 * Don't remove the request from the waitqueue here, as it might
1803		 * not actually be complete yet (we won't know until vfs_poll()
1804		 * is called), and we must not miss any wakeups.  POLLFREE is an
1805		 * exception to this; see below.
1806		 */
1807		if (req->work_scheduled) {
1808			req->work_need_resched = true;
1809		} else {
1810			schedule_work(&req->work);
1811			req->work_scheduled = true;
1812		}
1813
1814		/*
1815		 * If the waitqueue is being freed early but we can't complete
1816		 * the request inline, we have to tear down the request as best
1817		 * we can.  That means immediately removing the request from its
1818		 * waitqueue and preventing all further accesses to the
1819		 * waitqueue via the request.  We also need to schedule the
1820		 * completion work (done above).  Also mark the request as
1821		 * cancelled, to potentially skip an unneeded call to ->poll().
1822		 */
1823		if (mask & POLLFREE) {
1824			WRITE_ONCE(req->cancelled, true);
1825			list_del_init(&req->wait.entry);
1826
1827			/*
1828			 * Careful: this *must* be the last step, since as soon
1829			 * as req->head is NULL'ed out, the request can be
1830			 * completed and freed, since aio_poll_complete_work()
1831			 * will no longer need to take the waitqueue lock.
1832			 */
1833			smp_store_release(&req->head, NULL);
1834		}
1835	}
1836	return 1;
1837}
1838
1839struct aio_poll_table {
1840	struct poll_table_struct	pt;
1841	struct aio_kiocb		*iocb;
1842	bool				queued;
1843	int				error;
1844};
1845
1846static void
1847aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1848		struct poll_table_struct *p)
1849{
1850	struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1851
1852	/* multiple wait queues per file are not supported */
1853	if (unlikely(pt->queued)) {
1854		pt->error = -EINVAL;
1855		return;
1856	}
1857
1858	pt->queued = true;
1859	pt->error = 0;
1860	pt->iocb->poll.head = head;
1861	add_wait_queue(head, &pt->iocb->poll.wait);
1862}
1863
1864static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1865{
1866	struct kioctx *ctx = aiocb->ki_ctx;
1867	struct poll_iocb *req = &aiocb->poll;
1868	struct aio_poll_table apt;
1869	bool cancel = false;
1870	__poll_t mask;
1871
1872	/* reject any unknown events outside the normal event mask. */
1873	if ((u16)iocb->aio_buf != iocb->aio_buf)
1874		return -EINVAL;
1875	/* reject fields that are not defined for poll */
1876	if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1877		return -EINVAL;
1878
1879	INIT_WORK(&req->work, aio_poll_complete_work);
1880	req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1881
1882	req->head = NULL;
1883	req->cancelled = false;
1884	req->work_scheduled = false;
1885	req->work_need_resched = false;
1886
1887	apt.pt._qproc = aio_poll_queue_proc;
1888	apt.pt._key = req->events;
1889	apt.iocb = aiocb;
1890	apt.queued = false;
1891	apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1892
1893	/* initialized the list so that we can do list_empty checks */
1894	INIT_LIST_HEAD(&req->wait.entry);
1895	init_waitqueue_func_entry(&req->wait, aio_poll_wake);
1896
1897	mask = vfs_poll(req->file, &apt.pt) & req->events;
1898	spin_lock_irq(&ctx->ctx_lock);
1899	if (likely(apt.queued)) {
1900		bool on_queue = poll_iocb_lock_wq(req);
1901
1902		if (!on_queue || req->work_scheduled) {
1903			/*
1904			 * aio_poll_wake() already either scheduled the async
1905			 * completion work, or completed the request inline.
1906			 */
1907			if (apt.error) /* unsupported case: multiple queues */
1908				cancel = true;
1909			apt.error = 0;
1910			mask = 0;
1911		}
1912		if (mask || apt.error) {
1913			/* Steal to complete synchronously. */
1914			list_del_init(&req->wait.entry);
1915		} else if (cancel) {
1916			/* Cancel if possible (may be too late though). */
1917			WRITE_ONCE(req->cancelled, true);
1918		} else if (on_queue) {
1919			/*
1920			 * Actually waiting for an event, so add the request to
1921			 * active_reqs so that it can be cancelled if needed.
1922			 */
1923			list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
1924			aiocb->ki_cancel = aio_poll_cancel;
1925		}
1926		if (on_queue)
1927			poll_iocb_unlock_wq(req);
1928	}
1929	if (mask) { /* no async, we'd stolen it */
1930		aiocb->ki_res.res = mangle_poll(mask);
1931		apt.error = 0;
1932	}
1933	spin_unlock_irq(&ctx->ctx_lock);
1934	if (mask)
1935		iocb_put(aiocb);
1936	return apt.error;
1937}
1938
1939static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1940			   struct iocb __user *user_iocb, struct aio_kiocb *req,
1941			   bool compat)
1942{
1943	req->ki_filp = fget(iocb->aio_fildes);
1944	if (unlikely(!req->ki_filp))
1945		return -EBADF;
1946
1947	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1948		struct eventfd_ctx *eventfd;
1949		/*
1950		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1951		 * instance of the file* now. The file descriptor must be
1952		 * an eventfd() fd, and will be signaled for each completed
1953		 * event using the eventfd_signal() function.
1954		 */
1955		eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
1956		if (IS_ERR(eventfd))
1957			return PTR_ERR(eventfd);
1958
1959		req->ki_eventfd = eventfd;
1960	}
1961
1962	if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1963		pr_debug("EFAULT: aio_key\n");
1964		return -EFAULT;
1965	}
1966
1967	req->ki_res.obj = (u64)(unsigned long)user_iocb;
1968	req->ki_res.data = iocb->aio_data;
1969	req->ki_res.res = 0;
1970	req->ki_res.res2 = 0;
1971
1972	switch (iocb->aio_lio_opcode) {
1973	case IOCB_CMD_PREAD:
1974		return aio_read(&req->rw, iocb, false, compat);
1975	case IOCB_CMD_PWRITE:
1976		return aio_write(&req->rw, iocb, false, compat);
1977	case IOCB_CMD_PREADV:
1978		return aio_read(&req->rw, iocb, true, compat);
1979	case IOCB_CMD_PWRITEV:
1980		return aio_write(&req->rw, iocb, true, compat);
1981	case IOCB_CMD_FSYNC:
1982		return aio_fsync(&req->fsync, iocb, false);
1983	case IOCB_CMD_FDSYNC:
1984		return aio_fsync(&req->fsync, iocb, true);
1985	case IOCB_CMD_POLL:
1986		return aio_poll(req, iocb);
1987	default:
1988		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
1989		return -EINVAL;
1990	}
1991}
1992
1993static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1994			 bool compat)
1995{
1996	struct aio_kiocb *req;
1997	struct iocb iocb;
1998	int err;
1999
2000	if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
2001		return -EFAULT;
2002
2003	/* enforce forwards compatibility on users */
2004	if (unlikely(iocb.aio_reserved2)) {
2005		pr_debug("EINVAL: reserve field set\n");
2006		return -EINVAL;
2007	}
2008
2009	/* prevent overflows */
2010	if (unlikely(
2011	    (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
2012	    (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
2013	    ((ssize_t)iocb.aio_nbytes < 0)
2014	   )) {
2015		pr_debug("EINVAL: overflow check\n");
2016		return -EINVAL;
2017	}
2018
2019	req = aio_get_req(ctx);
2020	if (unlikely(!req))
2021		return -EAGAIN;
2022
2023	err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
2024
2025	/* Done with the synchronous reference */
2026	iocb_put(req);
2027
2028	/*
2029	 * If err is 0, we'd either done aio_complete() ourselves or have
2030	 * arranged for that to be done asynchronously.  Anything non-zero
2031	 * means that we need to destroy req ourselves.
2032	 */
2033	if (unlikely(err)) {
2034		iocb_destroy(req);
2035		put_reqs_available(ctx, 1);
2036	}
2037	return err;
2038}
2039
2040/* sys_io_submit:
2041 *	Queue the nr iocbs pointed to by iocbpp for processing.  Returns
2042 *	the number of iocbs queued.  May return -EINVAL if the aio_context
2043 *	specified by ctx_id is invalid, if nr is < 0, if the iocb at
2044 *	*iocbpp[0] is not properly initialized, if the operation specified
2045 *	is invalid for the file descriptor in the iocb.  May fail with
2046 *	-EFAULT if any of the data structures point to invalid data.  May
2047 *	fail with -EBADF if the file descriptor specified in the first
2048 *	iocb is invalid.  May fail with -EAGAIN if insufficient resources
2049 *	are available to queue any iocbs.  Will return 0 if nr is 0.  Will
2050 *	fail with -ENOSYS if not implemented.
2051 */
2052SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2053		struct iocb __user * __user *, iocbpp)
2054{
2055	struct kioctx *ctx;
2056	long ret = 0;
2057	int i = 0;
2058	struct blk_plug plug;
2059
2060	if (unlikely(nr < 0))
2061		return -EINVAL;
2062
2063	ctx = lookup_ioctx(ctx_id);
2064	if (unlikely(!ctx)) {
2065		pr_debug("EINVAL: invalid context id\n");
2066		return -EINVAL;
2067	}
2068
2069	if (nr > ctx->nr_events)
2070		nr = ctx->nr_events;
2071
2072	if (nr > AIO_PLUG_THRESHOLD)
2073		blk_start_plug(&plug);
2074	for (i = 0; i < nr; i++) {
2075		struct iocb __user *user_iocb;
2076
2077		if (unlikely(get_user(user_iocb, iocbpp + i))) {
2078			ret = -EFAULT;
2079			break;
2080		}
2081
2082		ret = io_submit_one(ctx, user_iocb, false);
2083		if (ret)
2084			break;
2085	}
2086	if (nr > AIO_PLUG_THRESHOLD)
2087		blk_finish_plug(&plug);
2088
2089	percpu_ref_put(&ctx->users);
2090	return i ? i : ret;
2091}
2092
2093#ifdef CONFIG_COMPAT
2094COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2095		       int, nr, compat_uptr_t __user *, iocbpp)
2096{
2097	struct kioctx *ctx;
2098	long ret = 0;
2099	int i = 0;
2100	struct blk_plug plug;
2101
2102	if (unlikely(nr < 0))
2103		return -EINVAL;
2104
2105	ctx = lookup_ioctx(ctx_id);
2106	if (unlikely(!ctx)) {
2107		pr_debug("EINVAL: invalid context id\n");
2108		return -EINVAL;
2109	}
2110
2111	if (nr > ctx->nr_events)
2112		nr = ctx->nr_events;
2113
2114	if (nr > AIO_PLUG_THRESHOLD)
2115		blk_start_plug(&plug);
2116	for (i = 0; i < nr; i++) {
2117		compat_uptr_t user_iocb;
2118
2119		if (unlikely(get_user(user_iocb, iocbpp + i))) {
2120			ret = -EFAULT;
2121			break;
2122		}
2123
2124		ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
2125		if (ret)
2126			break;
2127	}
2128	if (nr > AIO_PLUG_THRESHOLD)
2129		blk_finish_plug(&plug);
2130
2131	percpu_ref_put(&ctx->users);
2132	return i ? i : ret;
2133}
2134#endif
2135
2136/* sys_io_cancel:
2137 *	Attempts to cancel an iocb previously passed to io_submit.  If
2138 *	the operation is successfully cancelled, the resulting event is
2139 *	copied into the memory pointed to by result without being placed
2140 *	into the completion queue and 0 is returned.  May fail with
2141 *	-EFAULT if any of the data structures pointed to are invalid.
2142 *	May fail with -EINVAL if aio_context specified by ctx_id is
2143 *	invalid.  May fail with -EAGAIN if the iocb specified was not
2144 *	cancelled.  Will fail with -ENOSYS if not implemented.
2145 */
2146SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2147		struct io_event __user *, result)
2148{
2149	struct kioctx *ctx;
2150	struct aio_kiocb *kiocb;
2151	int ret = -EINVAL;
2152	u32 key;
2153	u64 obj = (u64)(unsigned long)iocb;
2154
2155	if (unlikely(get_user(key, &iocb->aio_key)))
2156		return -EFAULT;
2157	if (unlikely(key != KIOCB_KEY))
2158		return -EINVAL;
2159
2160	ctx = lookup_ioctx(ctx_id);
2161	if (unlikely(!ctx))
2162		return -EINVAL;
2163
2164	spin_lock_irq(&ctx->ctx_lock);
2165	/* TODO: use a hash or array, this sucks. */
2166	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2167		if (kiocb->ki_res.obj == obj) {
2168			ret = kiocb->ki_cancel(&kiocb->rw);
2169			list_del_init(&kiocb->ki_list);
2170			break;
2171		}
2172	}
2173	spin_unlock_irq(&ctx->ctx_lock);
2174
2175	if (!ret) {
2176		/*
2177		 * The result argument is no longer used - the io_event is
2178		 * always delivered via the ring buffer. -EINPROGRESS indicates
2179		 * cancellation is progress:
2180		 */
2181		ret = -EINPROGRESS;
2182	}
2183
2184	percpu_ref_put(&ctx->users);
2185
2186	return ret;
2187}
2188
2189static long do_io_getevents(aio_context_t ctx_id,
2190		long min_nr,
2191		long nr,
2192		struct io_event __user *events,
2193		struct timespec64 *ts)
2194{
2195	ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
2196	struct kioctx *ioctx = lookup_ioctx(ctx_id);
2197	long ret = -EINVAL;
2198
2199	if (likely(ioctx)) {
2200		if (likely(min_nr <= nr && min_nr >= 0))
2201			ret = read_events(ioctx, min_nr, nr, events, until);
2202		percpu_ref_put(&ioctx->users);
2203	}
2204
2205	return ret;
2206}
2207
2208/* io_getevents:
2209 *	Attempts to read at least min_nr events and up to nr events from
2210 *	the completion queue for the aio_context specified by ctx_id. If
2211 *	it succeeds, the number of read events is returned. May fail with
2212 *	-EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2213 *	out of range, if timeout is out of range.  May fail with -EFAULT
2214 *	if any of the memory specified is invalid.  May return 0 or
2215 *	< min_nr if the timeout specified by timeout has elapsed
2216 *	before sufficient events are available, where timeout == NULL
2217 *	specifies an infinite timeout. Note that the timeout pointed to by
2218 *	timeout is relative.  Will fail with -ENOSYS if not implemented.
2219 */
2220#ifdef CONFIG_64BIT
2221
2222SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2223		long, min_nr,
2224		long, nr,
2225		struct io_event __user *, events,
2226		struct __kernel_timespec __user *, timeout)
2227{
2228	struct timespec64	ts;
2229	int			ret;
2230
2231	if (timeout && unlikely(get_timespec64(&ts, timeout)))
2232		return -EFAULT;
2233
2234	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2235	if (!ret && signal_pending(current))
2236		ret = -EINTR;
2237	return ret;
2238}
2239
2240#endif
2241
2242struct __aio_sigset {
2243	const sigset_t __user	*sigmask;
2244	size_t		sigsetsize;
2245};
2246
2247SYSCALL_DEFINE6(io_pgetevents,
2248		aio_context_t, ctx_id,
2249		long, min_nr,
2250		long, nr,
2251		struct io_event __user *, events,
2252		struct __kernel_timespec __user *, timeout,
2253		const struct __aio_sigset __user *, usig)
2254{
2255	struct __aio_sigset	ksig = { NULL, };
2256	struct timespec64	ts;
2257	bool interrupted;
2258	int ret;
2259
2260	if (timeout && unlikely(get_timespec64(&ts, timeout)))
2261		return -EFAULT;
2262
2263	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2264		return -EFAULT;
2265
2266	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2267	if (ret)
2268		return ret;
2269
2270	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2271
2272	interrupted = signal_pending(current);
2273	restore_saved_sigmask_unless(interrupted);
2274	if (interrupted && !ret)
2275		ret = -ERESTARTNOHAND;
2276
2277	return ret;
2278}
2279
2280#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2281
2282SYSCALL_DEFINE6(io_pgetevents_time32,
2283		aio_context_t, ctx_id,
2284		long, min_nr,
2285		long, nr,
2286		struct io_event __user *, events,
2287		struct old_timespec32 __user *, timeout,
2288		const struct __aio_sigset __user *, usig)
2289{
2290	struct __aio_sigset	ksig = { NULL, };
2291	struct timespec64	ts;
2292	bool interrupted;
2293	int ret;
2294
2295	if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2296		return -EFAULT;
2297
2298	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2299		return -EFAULT;
2300
2301
2302	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2303	if (ret)
2304		return ret;
2305
2306	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2307
2308	interrupted = signal_pending(current);
2309	restore_saved_sigmask_unless(interrupted);
2310	if (interrupted && !ret)
2311		ret = -ERESTARTNOHAND;
2312
2313	return ret;
2314}
2315
2316#endif
2317
2318#if defined(CONFIG_COMPAT_32BIT_TIME)
2319
2320SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2321		__s32, min_nr,
2322		__s32, nr,
2323		struct io_event __user *, events,
2324		struct old_timespec32 __user *, timeout)
2325{
2326	struct timespec64 t;
2327	int ret;
2328
2329	if (timeout && get_old_timespec32(&t, timeout))
2330		return -EFAULT;
2331
2332	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2333	if (!ret && signal_pending(current))
2334		ret = -EINTR;
2335	return ret;
2336}
2337
2338#endif
2339
2340#ifdef CONFIG_COMPAT
2341
2342struct __compat_aio_sigset {
2343	compat_uptr_t		sigmask;
2344	compat_size_t		sigsetsize;
2345};
2346
2347#if defined(CONFIG_COMPAT_32BIT_TIME)
2348
2349COMPAT_SYSCALL_DEFINE6(io_pgetevents,
2350		compat_aio_context_t, ctx_id,
2351		compat_long_t, min_nr,
2352		compat_long_t, nr,
2353		struct io_event __user *, events,
2354		struct old_timespec32 __user *, timeout,
2355		const struct __compat_aio_sigset __user *, usig)
2356{
2357	struct __compat_aio_sigset ksig = { 0, };
2358	struct timespec64 t;
2359	bool interrupted;
2360	int ret;
2361
2362	if (timeout && get_old_timespec32(&t, timeout))
2363		return -EFAULT;
2364
2365	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2366		return -EFAULT;
2367
2368	ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2369	if (ret)
2370		return ret;
2371
2372	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2373
2374	interrupted = signal_pending(current);
2375	restore_saved_sigmask_unless(interrupted);
2376	if (interrupted && !ret)
2377		ret = -ERESTARTNOHAND;
2378
2379	return ret;
2380}
2381
2382#endif
2383
2384COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2385		compat_aio_context_t, ctx_id,
2386		compat_long_t, min_nr,
2387		compat_long_t, nr,
2388		struct io_event __user *, events,
2389		struct __kernel_timespec __user *, timeout,
2390		const struct __compat_aio_sigset __user *, usig)
2391{
2392	struct __compat_aio_sigset ksig = { 0, };
2393	struct timespec64 t;
2394	bool interrupted;
2395	int ret;
2396
2397	if (timeout && get_timespec64(&t, timeout))
2398		return -EFAULT;
2399
2400	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2401		return -EFAULT;
2402
2403	ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2404	if (ret)
2405		return ret;
2406
2407	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2408
2409	interrupted = signal_pending(current);
2410	restore_saved_sigmask_unless(interrupted);
2411	if (interrupted && !ret)
2412		ret = -ERESTARTNOHAND;
2413
2414	return ret;
2415}
2416#endif