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[] __counted_by(nr);
  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
 244static void __init aio_sysctl_init(void)
 245{
 246	register_sysctl_init("fs", aio_sysctls);
 247}
 248#else
 249#define aio_sysctl_init() do { } while (0)
 250#endif
 251
 252static struct kmem_cache	*kiocb_cachep;
 253static struct kmem_cache	*kioctx_cachep;
 254
 255static struct vfsmount *aio_mnt;
 256
 257static const struct file_operations aio_ring_fops;
 258static const struct address_space_operations aio_ctx_aops;
 259
 260static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
 261{
 
 262	struct file *file;
 
 263	struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
 264	if (IS_ERR(inode))
 265		return ERR_CAST(inode);
 266
 267	inode->i_mapping->a_ops = &aio_ctx_aops;
 268	inode->i_mapping->i_private_data = ctx;
 269	inode->i_size = PAGE_SIZE * nr_pages;
 270
 271	file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
 272				O_RDWR, &aio_ring_fops);
 273	if (IS_ERR(file))
 274		iput(inode);
 
 
 
 
 
 
 
 
 
 
 
 
 275	return file;
 276}
 277
 278static int aio_init_fs_context(struct fs_context *fc)
 
 279{
 280	if (!init_pseudo(fc, AIO_RING_MAGIC))
 281		return -ENOMEM;
 282	fc->s_iflags |= SB_I_NOEXEC;
 283	return 0;
 284}
 285
 286/* aio_setup
 287 *	Creates the slab caches used by the aio routines, panic on
 288 *	failure as this is done early during the boot sequence.
 289 */
 290static int __init aio_setup(void)
 291{
 292	static struct file_system_type aio_fs = {
 293		.name		= "aio",
 294		.init_fs_context = aio_init_fs_context,
 295		.kill_sb	= kill_anon_super,
 296	};
 297	aio_mnt = kern_mount(&aio_fs);
 298	if (IS_ERR(aio_mnt))
 299		panic("Failed to create aio fs mount.");
 300
 301	kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 302	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 303	aio_sysctl_init();
 
 
 304	return 0;
 305}
 306__initcall(aio_setup);
 307
 308static void put_aio_ring_file(struct kioctx *ctx)
 309{
 310	struct file *aio_ring_file = ctx->aio_ring_file;
 311	struct address_space *i_mapping;
 312
 313	if (aio_ring_file) {
 314		truncate_setsize(file_inode(aio_ring_file), 0);
 315
 316		/* Prevent further access to the kioctx from migratepages */
 317		i_mapping = aio_ring_file->f_mapping;
 318		spin_lock(&i_mapping->i_private_lock);
 319		i_mapping->i_private_data = NULL;
 320		ctx->aio_ring_file = NULL;
 321		spin_unlock(&i_mapping->i_private_lock);
 322
 323		fput(aio_ring_file);
 324	}
 325}
 326
 327static void aio_free_ring(struct kioctx *ctx)
 328{
 329	int i;
 330
 331	/* Disconnect the kiotx from the ring file.  This prevents future
 332	 * accesses to the kioctx from page migration.
 333	 */
 334	put_aio_ring_file(ctx);
 335
 336	for (i = 0; i < ctx->nr_pages; i++) {
 337		struct page *page;
 338		pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
 339				page_count(ctx->ring_pages[i]));
 340		page = ctx->ring_pages[i];
 341		if (!page)
 342			continue;
 343		ctx->ring_pages[i] = NULL;
 344		put_page(page);
 345	}
 346
 347	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
 348		kfree(ctx->ring_pages);
 349		ctx->ring_pages = NULL;
 350	}
 351}
 352
 353static int aio_ring_mremap(struct vm_area_struct *vma)
 354{
 355	struct file *file = vma->vm_file;
 356	struct mm_struct *mm = vma->vm_mm;
 357	struct kioctx_table *table;
 358	int i, res = -EINVAL;
 359
 360	spin_lock(&mm->ioctx_lock);
 361	rcu_read_lock();
 362	table = rcu_dereference(mm->ioctx_table);
 363	if (!table)
 364		goto out_unlock;
 365
 366	for (i = 0; i < table->nr; i++) {
 367		struct kioctx *ctx;
 368
 369		ctx = rcu_dereference(table->table[i]);
 370		if (ctx && ctx->aio_ring_file == file) {
 371			if (!atomic_read(&ctx->dead)) {
 372				ctx->user_id = ctx->mmap_base = vma->vm_start;
 373				res = 0;
 374			}
 375			break;
 376		}
 377	}
 378
 379out_unlock:
 380	rcu_read_unlock();
 381	spin_unlock(&mm->ioctx_lock);
 382	return res;
 383}
 384
 385static const struct vm_operations_struct aio_ring_vm_ops = {
 386	.mremap		= aio_ring_mremap,
 387#if IS_ENABLED(CONFIG_MMU)
 388	.fault		= filemap_fault,
 389	.map_pages	= filemap_map_pages,
 390	.page_mkwrite	= filemap_page_mkwrite,
 391#endif
 392};
 393
 394static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
 395{
 396	vm_flags_set(vma, VM_DONTEXPAND);
 397	vma->vm_ops = &aio_ring_vm_ops;
 398	return 0;
 399}
 400
 401static const struct file_operations aio_ring_fops = {
 402	.mmap = aio_ring_mmap,
 403};
 404
 405#if IS_ENABLED(CONFIG_MIGRATION)
 406static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
 407			struct folio *src, enum migrate_mode mode)
 408{
 409	struct kioctx *ctx;
 410	unsigned long flags;
 411	pgoff_t idx;
 412	int rc;
 413
 414	/*
 415	 * We cannot support the _NO_COPY case here, because copy needs to
 416	 * happen under the ctx->completion_lock. That does not work with the
 417	 * migration workflow of MIGRATE_SYNC_NO_COPY.
 418	 */
 419	if (mode == MIGRATE_SYNC_NO_COPY)
 420		return -EINVAL;
 421
 422	rc = 0;
 423
 424	/* mapping->i_private_lock here protects against the kioctx teardown.  */
 425	spin_lock(&mapping->i_private_lock);
 426	ctx = mapping->i_private_data;
 427	if (!ctx) {
 428		rc = -EINVAL;
 429		goto out;
 430	}
 431
 432	/* The ring_lock mutex.  The prevents aio_read_events() from writing
 433	 * to the ring's head, and prevents page migration from mucking in
 434	 * a partially initialized kiotx.
 435	 */
 436	if (!mutex_trylock(&ctx->ring_lock)) {
 437		rc = -EAGAIN;
 438		goto out;
 439	}
 440
 441	idx = src->index;
 442	if (idx < (pgoff_t)ctx->nr_pages) {
 443		/* Make sure the old folio hasn't already been changed */
 444		if (ctx->ring_pages[idx] != &src->page)
 445			rc = -EAGAIN;
 446	} else
 447		rc = -EINVAL;
 448
 449	if (rc != 0)
 450		goto out_unlock;
 451
 452	/* Writeback must be complete */
 453	BUG_ON(folio_test_writeback(src));
 454	folio_get(dst);
 455
 456	rc = folio_migrate_mapping(mapping, dst, src, 1);
 457	if (rc != MIGRATEPAGE_SUCCESS) {
 458		folio_put(dst);
 459		goto out_unlock;
 460	}
 461
 462	/* Take completion_lock to prevent other writes to the ring buffer
 463	 * while the old folio is copied to the new.  This prevents new
 464	 * events from being lost.
 465	 */
 466	spin_lock_irqsave(&ctx->completion_lock, flags);
 467	folio_migrate_copy(dst, src);
 468	BUG_ON(ctx->ring_pages[idx] != &src->page);
 469	ctx->ring_pages[idx] = &dst->page;
 470	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 471
 472	/* The old folio is no longer accessible. */
 473	folio_put(src);
 474
 475out_unlock:
 476	mutex_unlock(&ctx->ring_lock);
 477out:
 478	spin_unlock(&mapping->i_private_lock);
 479	return rc;
 480}
 481#else
 482#define aio_migrate_folio NULL
 483#endif
 484
 485static const struct address_space_operations aio_ctx_aops = {
 486	.dirty_folio	= noop_dirty_folio,
 487	.migrate_folio	= aio_migrate_folio,
 
 
 488};
 489
 490static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 491{
 492	struct aio_ring *ring;
 
 493	struct mm_struct *mm = current->mm;
 494	unsigned long size, unused;
 495	int nr_pages;
 496	int i;
 497	struct file *file;
 498
 499	/* Compensate for the ring buffer's head/tail overlap entry */
 500	nr_events += 2;	/* 1 is required, 2 for good luck */
 501
 502	size = sizeof(struct aio_ring);
 503	size += sizeof(struct io_event) * nr_events;
 504
 505	nr_pages = PFN_UP(size);
 506	if (nr_pages < 0)
 507		return -EINVAL;
 508
 509	file = aio_private_file(ctx, nr_pages);
 510	if (IS_ERR(file)) {
 511		ctx->aio_ring_file = NULL;
 512		return -ENOMEM;
 513	}
 514
 515	ctx->aio_ring_file = file;
 516	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
 517			/ sizeof(struct io_event);
 518
 519	ctx->ring_pages = ctx->internal_pages;
 520	if (nr_pages > AIO_RING_PAGES) {
 521		ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
 522					  GFP_KERNEL);
 523		if (!ctx->ring_pages) {
 524			put_aio_ring_file(ctx);
 525			return -ENOMEM;
 526		}
 527	}
 528
 529	for (i = 0; i < nr_pages; i++) {
 530		struct page *page;
 531		page = find_or_create_page(file->f_mapping,
 532					   i, GFP_USER | __GFP_ZERO);
 533		if (!page)
 534			break;
 535		pr_debug("pid(%d) page[%d]->count=%d\n",
 536			 current->pid, i, page_count(page));
 537		SetPageUptodate(page);
 538		unlock_page(page);
 539
 540		ctx->ring_pages[i] = page;
 541	}
 542	ctx->nr_pages = i;
 543
 544	if (unlikely(i != nr_pages)) {
 545		aio_free_ring(ctx);
 546		return -ENOMEM;
 547	}
 548
 549	ctx->mmap_size = nr_pages * PAGE_SIZE;
 550	pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
 551
 552	if (mmap_write_lock_killable(mm)) {
 553		ctx->mmap_size = 0;
 554		aio_free_ring(ctx);
 555		return -EINTR;
 556	}
 557
 558	ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
 559				 PROT_READ | PROT_WRITE,
 560				 MAP_SHARED, 0, 0, &unused, NULL);
 561	mmap_write_unlock(mm);
 562	if (IS_ERR((void *)ctx->mmap_base)) {
 563		ctx->mmap_size = 0;
 564		aio_free_ring(ctx);
 565		return -ENOMEM;
 566	}
 567
 568	pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
 569
 570	ctx->user_id = ctx->mmap_base;
 571	ctx->nr_events = nr_events; /* trusted copy */
 572
 573	ring = page_address(ctx->ring_pages[0]);
 574	ring->nr = nr_events;	/* user copy */
 575	ring->id = ~0U;
 576	ring->head = ring->tail = 0;
 577	ring->magic = AIO_RING_MAGIC;
 578	ring->compat_features = AIO_RING_COMPAT_FEATURES;
 579	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
 580	ring->header_length = sizeof(struct aio_ring);
 
 581	flush_dcache_page(ctx->ring_pages[0]);
 582
 583	return 0;
 584}
 585
 586#define AIO_EVENTS_PER_PAGE	(PAGE_SIZE / sizeof(struct io_event))
 587#define AIO_EVENTS_FIRST_PAGE	((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
 588#define AIO_EVENTS_OFFSET	(AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
 589
 590void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
 591{
 592	struct aio_kiocb *req;
 593	struct kioctx *ctx;
 594	unsigned long flags;
 595
 596	/*
 597	 * kiocb didn't come from aio or is neither a read nor a write, hence
 598	 * ignore it.
 599	 */
 600	if (!(iocb->ki_flags & IOCB_AIO_RW))
 601		return;
 602
 603	req = container_of(iocb, struct aio_kiocb, rw);
 604
 605	if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
 606		return;
 607
 608	ctx = req->ki_ctx;
 
 609
 610	spin_lock_irqsave(&ctx->ctx_lock, flags);
 611	list_add_tail(&req->ki_list, &ctx->active_reqs);
 612	req->ki_cancel = cancel;
 
 613	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
 614}
 615EXPORT_SYMBOL(kiocb_set_cancel_fn);
 616
 617/*
 618 * free_ioctx() should be RCU delayed to synchronize against the RCU
 619 * protected lookup_ioctx() and also needs process context to call
 620 * aio_free_ring().  Use rcu_work.
 621 */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 622static void free_ioctx(struct work_struct *work)
 623{
 624	struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
 625					  free_rwork);
 626	pr_debug("freeing %p\n", ctx);
 627
 628	aio_free_ring(ctx);
 629	free_percpu(ctx->cpu);
 630	percpu_ref_exit(&ctx->reqs);
 631	percpu_ref_exit(&ctx->users);
 632	kmem_cache_free(kioctx_cachep, ctx);
 633}
 634
 635static void free_ioctx_reqs(struct percpu_ref *ref)
 636{
 637	struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
 638
 639	/* At this point we know that there are no any in-flight requests */
 640	if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
 641		complete(&ctx->rq_wait->comp);
 642
 643	/* Synchronize against RCU protected table->table[] dereferences */
 644	INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
 645	queue_rcu_work(system_wq, &ctx->free_rwork);
 646}
 647
 648/*
 649 * When this function runs, the kioctx has been removed from the "hash table"
 650 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
 651 * now it's safe to cancel any that need to be.
 652 */
 653static void free_ioctx_users(struct percpu_ref *ref)
 654{
 655	struct kioctx *ctx = container_of(ref, struct kioctx, users);
 656	struct aio_kiocb *req;
 657
 658	spin_lock_irq(&ctx->ctx_lock);
 659
 660	while (!list_empty(&ctx->active_reqs)) {
 661		req = list_first_entry(&ctx->active_reqs,
 662				       struct aio_kiocb, ki_list);
 663		req->ki_cancel(&req->rw);
 664		list_del_init(&req->ki_list);
 
 665	}
 666
 667	spin_unlock_irq(&ctx->ctx_lock);
 668
 669	percpu_ref_kill(&ctx->reqs);
 670	percpu_ref_put(&ctx->reqs);
 671}
 672
 673static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
 674{
 675	unsigned i, new_nr;
 676	struct kioctx_table *table, *old;
 677	struct aio_ring *ring;
 678
 679	spin_lock(&mm->ioctx_lock);
 680	table = rcu_dereference_raw(mm->ioctx_table);
 681
 682	while (1) {
 683		if (table)
 684			for (i = 0; i < table->nr; i++)
 685				if (!rcu_access_pointer(table->table[i])) {
 686					ctx->id = i;
 687					rcu_assign_pointer(table->table[i], ctx);
 688					spin_unlock(&mm->ioctx_lock);
 689
 690					/* While kioctx setup is in progress,
 691					 * we are protected from page migration
 692					 * changes ring_pages by ->ring_lock.
 693					 */
 694					ring = page_address(ctx->ring_pages[0]);
 695					ring->id = ctx->id;
 
 696					return 0;
 697				}
 698
 699		new_nr = (table ? table->nr : 1) * 4;
 700		spin_unlock(&mm->ioctx_lock);
 701
 702		table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
 
 703		if (!table)
 704			return -ENOMEM;
 705
 706		table->nr = new_nr;
 707
 708		spin_lock(&mm->ioctx_lock);
 709		old = rcu_dereference_raw(mm->ioctx_table);
 710
 711		if (!old) {
 712			rcu_assign_pointer(mm->ioctx_table, table);
 713		} else if (table->nr > old->nr) {
 714			memcpy(table->table, old->table,
 715			       old->nr * sizeof(struct kioctx *));
 716
 717			rcu_assign_pointer(mm->ioctx_table, table);
 718			kfree_rcu(old, rcu);
 719		} else {
 720			kfree(table);
 721			table = old;
 722		}
 723	}
 724}
 725
 726static void aio_nr_sub(unsigned nr)
 727{
 728	spin_lock(&aio_nr_lock);
 729	if (WARN_ON(aio_nr - nr > aio_nr))
 730		aio_nr = 0;
 731	else
 732		aio_nr -= nr;
 733	spin_unlock(&aio_nr_lock);
 734}
 735
 736/* ioctx_alloc
 737 *	Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
 738 */
 739static struct kioctx *ioctx_alloc(unsigned nr_events)
 740{
 741	struct mm_struct *mm = current->mm;
 742	struct kioctx *ctx;
 743	int err = -ENOMEM;
 744
 745	/*
 746	 * Store the original nr_events -- what userspace passed to io_setup(),
 747	 * for counting against the global limit -- before it changes.
 748	 */
 749	unsigned int max_reqs = nr_events;
 750
 751	/*
 752	 * We keep track of the number of available ringbuffer slots, to prevent
 753	 * overflow (reqs_available), and we also use percpu counters for this.
 754	 *
 755	 * So since up to half the slots might be on other cpu's percpu counters
 756	 * and unavailable, double nr_events so userspace sees what they
 757	 * expected: additionally, we move req_batch slots to/from percpu
 758	 * counters at a time, so make sure that isn't 0:
 759	 */
 760	nr_events = max(nr_events, num_possible_cpus() * 4);
 761	nr_events *= 2;
 762
 763	/* Prevent overflows */
 764	if (nr_events > (0x10000000U / sizeof(struct io_event))) {
 765		pr_debug("ENOMEM: nr_events too high\n");
 766		return ERR_PTR(-EINVAL);
 767	}
 768
 769	if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
 770		return ERR_PTR(-EAGAIN);
 771
 772	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
 773	if (!ctx)
 774		return ERR_PTR(-ENOMEM);
 775
 776	ctx->max_reqs = max_reqs;
 777
 778	spin_lock_init(&ctx->ctx_lock);
 779	spin_lock_init(&ctx->completion_lock);
 780	mutex_init(&ctx->ring_lock);
 781	/* Protect against page migration throughout kiotx setup by keeping
 782	 * the ring_lock mutex held until setup is complete. */
 783	mutex_lock(&ctx->ring_lock);
 784	init_waitqueue_head(&ctx->wait);
 785
 786	INIT_LIST_HEAD(&ctx->active_reqs);
 787
 788	if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
 789		goto err;
 790
 791	if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
 792		goto err;
 793
 794	ctx->cpu = alloc_percpu(struct kioctx_cpu);
 795	if (!ctx->cpu)
 796		goto err;
 797
 798	err = aio_setup_ring(ctx, nr_events);
 799	if (err < 0)
 800		goto err;
 801
 802	atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
 803	ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
 804	if (ctx->req_batch < 1)
 805		ctx->req_batch = 1;
 806
 807	/* limit the number of system wide aios */
 808	spin_lock(&aio_nr_lock);
 809	if (aio_nr + ctx->max_reqs > aio_max_nr ||
 810	    aio_nr + ctx->max_reqs < aio_nr) {
 811		spin_unlock(&aio_nr_lock);
 812		err = -EAGAIN;
 813		goto err_ctx;
 814	}
 815	aio_nr += ctx->max_reqs;
 816	spin_unlock(&aio_nr_lock);
 817
 818	percpu_ref_get(&ctx->users);	/* io_setup() will drop this ref */
 819	percpu_ref_get(&ctx->reqs);	/* free_ioctx_users() will drop this */
 820
 821	err = ioctx_add_table(ctx, mm);
 822	if (err)
 823		goto err_cleanup;
 824
 825	/* Release the ring_lock mutex now that all setup is complete. */
 826	mutex_unlock(&ctx->ring_lock);
 827
 828	pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
 829		 ctx, ctx->user_id, mm, ctx->nr_events);
 830	return ctx;
 831
 832err_cleanup:
 833	aio_nr_sub(ctx->max_reqs);
 834err_ctx:
 835	atomic_set(&ctx->dead, 1);
 836	if (ctx->mmap_size)
 837		vm_munmap(ctx->mmap_base, ctx->mmap_size);
 838	aio_free_ring(ctx);
 839err:
 840	mutex_unlock(&ctx->ring_lock);
 841	free_percpu(ctx->cpu);
 842	percpu_ref_exit(&ctx->reqs);
 843	percpu_ref_exit(&ctx->users);
 844	kmem_cache_free(kioctx_cachep, ctx);
 845	pr_debug("error allocating ioctx %d\n", err);
 846	return ERR_PTR(err);
 847}
 848
 849/* kill_ioctx
 850 *	Cancels all outstanding aio requests on an aio context.  Used
 851 *	when the processes owning a context have all exited to encourage
 852 *	the rapid destruction of the kioctx.
 853 */
 854static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
 855		      struct ctx_rq_wait *wait)
 856{
 857	struct kioctx_table *table;
 858
 859	spin_lock(&mm->ioctx_lock);
 860	if (atomic_xchg(&ctx->dead, 1)) {
 861		spin_unlock(&mm->ioctx_lock);
 862		return -EINVAL;
 863	}
 864
 865	table = rcu_dereference_raw(mm->ioctx_table);
 866	WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
 867	RCU_INIT_POINTER(table->table[ctx->id], NULL);
 868	spin_unlock(&mm->ioctx_lock);
 869
 870	/* free_ioctx_reqs() will do the necessary RCU synchronization */
 871	wake_up_all(&ctx->wait);
 872
 873	/*
 874	 * It'd be more correct to do this in free_ioctx(), after all
 875	 * the outstanding kiocbs have finished - but by then io_destroy
 876	 * has already returned, so io_setup() could potentially return
 877	 * -EAGAIN with no ioctxs actually in use (as far as userspace
 878	 *  could tell).
 879	 */
 880	aio_nr_sub(ctx->max_reqs);
 881
 882	if (ctx->mmap_size)
 883		vm_munmap(ctx->mmap_base, ctx->mmap_size);
 884
 885	ctx->rq_wait = wait;
 886	percpu_ref_kill(&ctx->users);
 887	return 0;
 888}
 889
 890/*
 891 * exit_aio: called when the last user of mm goes away.  At this point, there is
 892 * no way for any new requests to be submited or any of the io_* syscalls to be
 893 * called on the context.
 894 *
 895 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
 896 * them.
 897 */
 898void exit_aio(struct mm_struct *mm)
 899{
 900	struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
 901	struct ctx_rq_wait wait;
 902	int i, skipped;
 903
 904	if (!table)
 905		return;
 906
 907	atomic_set(&wait.count, table->nr);
 908	init_completion(&wait.comp);
 909
 910	skipped = 0;
 911	for (i = 0; i < table->nr; ++i) {
 912		struct kioctx *ctx =
 913			rcu_dereference_protected(table->table[i], true);
 914
 915		if (!ctx) {
 916			skipped++;
 917			continue;
 918		}
 919
 920		/*
 921		 * We don't need to bother with munmap() here - exit_mmap(mm)
 922		 * is coming and it'll unmap everything. And we simply can't,
 923		 * this is not necessarily our ->mm.
 924		 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
 925		 * that it needs to unmap the area, just set it to 0.
 926		 */
 927		ctx->mmap_size = 0;
 928		kill_ioctx(mm, ctx, &wait);
 929	}
 930
 931	if (!atomic_sub_and_test(skipped, &wait.count)) {
 932		/* Wait until all IO for the context are done. */
 933		wait_for_completion(&wait.comp);
 934	}
 935
 936	RCU_INIT_POINTER(mm->ioctx_table, NULL);
 937	kfree(table);
 938}
 939
 940static void put_reqs_available(struct kioctx *ctx, unsigned nr)
 941{
 942	struct kioctx_cpu *kcpu;
 943	unsigned long flags;
 944
 945	local_irq_save(flags);
 946	kcpu = this_cpu_ptr(ctx->cpu);
 947	kcpu->reqs_available += nr;
 948
 949	while (kcpu->reqs_available >= ctx->req_batch * 2) {
 950		kcpu->reqs_available -= ctx->req_batch;
 951		atomic_add(ctx->req_batch, &ctx->reqs_available);
 952	}
 953
 954	local_irq_restore(flags);
 955}
 956
 957static bool __get_reqs_available(struct kioctx *ctx)
 958{
 959	struct kioctx_cpu *kcpu;
 960	bool ret = false;
 961	unsigned long flags;
 962
 963	local_irq_save(flags);
 964	kcpu = this_cpu_ptr(ctx->cpu);
 965	if (!kcpu->reqs_available) {
 966		int avail = atomic_read(&ctx->reqs_available);
 967
 968		do {
 969			if (avail < ctx->req_batch)
 970				goto out;
 971		} while (!atomic_try_cmpxchg(&ctx->reqs_available,
 972					     &avail, avail - ctx->req_batch));
 
 
 
 973
 974		kcpu->reqs_available += ctx->req_batch;
 975	}
 976
 977	ret = true;
 978	kcpu->reqs_available--;
 979out:
 980	local_irq_restore(flags);
 981	return ret;
 982}
 983
 984/* refill_reqs_available
 985 *	Updates the reqs_available reference counts used for tracking the
 986 *	number of free slots in the completion ring.  This can be called
 987 *	from aio_complete() (to optimistically update reqs_available) or
 988 *	from aio_get_req() (the we're out of events case).  It must be
 989 *	called holding ctx->completion_lock.
 990 */
 991static void refill_reqs_available(struct kioctx *ctx, unsigned head,
 992                                  unsigned tail)
 993{
 994	unsigned events_in_ring, completed;
 995
 996	/* Clamp head since userland can write to it. */
 997	head %= ctx->nr_events;
 998	if (head <= tail)
 999		events_in_ring = tail - head;
1000	else
1001		events_in_ring = ctx->nr_events - (head - tail);
1002
1003	completed = ctx->completed_events;
1004	if (events_in_ring < completed)
1005		completed -= events_in_ring;
1006	else
1007		completed = 0;
1008
1009	if (!completed)
1010		return;
1011
1012	ctx->completed_events -= completed;
1013	put_reqs_available(ctx, completed);
1014}
1015
1016/* user_refill_reqs_available
1017 *	Called to refill reqs_available when aio_get_req() encounters an
1018 *	out of space in the completion ring.
1019 */
1020static void user_refill_reqs_available(struct kioctx *ctx)
1021{
1022	spin_lock_irq(&ctx->completion_lock);
1023	if (ctx->completed_events) {
1024		struct aio_ring *ring;
1025		unsigned head;
1026
1027		/* Access of ring->head may race with aio_read_events_ring()
1028		 * here, but that's okay since whether we read the old version
1029		 * or the new version, and either will be valid.  The important
1030		 * part is that head cannot pass tail since we prevent
1031		 * aio_complete() from updating tail by holding
1032		 * ctx->completion_lock.  Even if head is invalid, the check
1033		 * against ctx->completed_events below will make sure we do the
1034		 * safe/right thing.
1035		 */
1036		ring = page_address(ctx->ring_pages[0]);
1037		head = ring->head;
 
1038
1039		refill_reqs_available(ctx, head, ctx->tail);
1040	}
1041
1042	spin_unlock_irq(&ctx->completion_lock);
1043}
1044
1045static bool get_reqs_available(struct kioctx *ctx)
1046{
1047	if (__get_reqs_available(ctx))
1048		return true;
1049	user_refill_reqs_available(ctx);
1050	return __get_reqs_available(ctx);
1051}
1052
1053/* aio_get_req
1054 *	Allocate a slot for an aio request.
1055 * Returns NULL if no requests are free.
1056 *
1057 * The refcount is initialized to 2 - one for the async op completion,
1058 * one for the synchronous code that does this.
1059 */
1060static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1061{
1062	struct aio_kiocb *req;
1063
1064	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
1065	if (unlikely(!req))
1066		return NULL;
1067
1068	if (unlikely(!get_reqs_available(ctx))) {
1069		kmem_cache_free(kiocb_cachep, req);
1070		return NULL;
1071	}
1072
 
 
 
 
1073	percpu_ref_get(&ctx->reqs);
 
1074	req->ki_ctx = ctx;
1075	INIT_LIST_HEAD(&req->ki_list);
1076	refcount_set(&req->ki_refcnt, 2);
1077	req->ki_eventfd = NULL;
1078	return req;
 
 
 
 
 
 
 
 
 
 
 
 
1079}
1080
1081static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1082{
1083	struct aio_ring __user *ring  = (void __user *)ctx_id;
1084	struct mm_struct *mm = current->mm;
1085	struct kioctx *ctx, *ret = NULL;
1086	struct kioctx_table *table;
1087	unsigned id;
1088
1089	if (get_user(id, &ring->id))
1090		return NULL;
1091
1092	rcu_read_lock();
1093	table = rcu_dereference(mm->ioctx_table);
1094
1095	if (!table || id >= table->nr)
1096		goto out;
1097
1098	id = array_index_nospec(id, table->nr);
1099	ctx = rcu_dereference(table->table[id]);
1100	if (ctx && ctx->user_id == ctx_id) {
1101		if (percpu_ref_tryget_live(&ctx->users))
1102			ret = ctx;
1103	}
1104out:
1105	rcu_read_unlock();
1106	return ret;
1107}
1108
1109static inline void iocb_destroy(struct aio_kiocb *iocb)
1110{
1111	if (iocb->ki_eventfd)
1112		eventfd_ctx_put(iocb->ki_eventfd);
1113	if (iocb->ki_filp)
1114		fput(iocb->ki_filp);
1115	percpu_ref_put(&iocb->ki_ctx->reqs);
1116	kmem_cache_free(kiocb_cachep, iocb);
1117}
1118
1119struct aio_waiter {
1120	struct wait_queue_entry	w;
1121	size_t			min_nr;
1122};
1123
1124/* aio_complete
1125 *	Called when the io request on the given iocb is complete.
1126 */
1127static void aio_complete(struct aio_kiocb *iocb)
1128{
 
1129	struct kioctx	*ctx = iocb->ki_ctx;
1130	struct aio_ring	*ring;
1131	struct io_event	*ev_page, *event;
1132	unsigned tail, pos, head, avail;
1133	unsigned long	flags;
1134
1135	/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1136	 * Add a completion event to the ring buffer. Must be done holding
1137	 * ctx->completion_lock to prevent other code from messing with the tail
1138	 * pointer since we might be called from irq context.
1139	 */
1140	spin_lock_irqsave(&ctx->completion_lock, flags);
1141
1142	tail = ctx->tail;
1143	pos = tail + AIO_EVENTS_OFFSET;
1144
1145	if (++tail >= ctx->nr_events)
1146		tail = 0;
1147
1148	ev_page = page_address(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1149	event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1150
1151	*event = iocb->ki_res;
 
 
 
1152
 
1153	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1154
1155	pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1156		 (void __user *)(unsigned long)iocb->ki_res.obj,
1157		 iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1158
1159	/* after flagging the request as done, we
1160	 * must never even look at it again
1161	 */
1162	smp_wmb();	/* make event visible before updating tail */
1163
1164	ctx->tail = tail;
1165
1166	ring = page_address(ctx->ring_pages[0]);
1167	head = ring->head;
1168	ring->tail = tail;
 
1169	flush_dcache_page(ctx->ring_pages[0]);
1170
1171	ctx->completed_events++;
1172	if (ctx->completed_events > 1)
1173		refill_reqs_available(ctx, head, tail);
1174
1175	avail = tail > head
1176		? tail - head
1177		: tail + ctx->nr_events - head;
1178	spin_unlock_irqrestore(&ctx->completion_lock, flags);
1179
1180	pr_debug("added to ring %p at [%u]\n", iocb, tail);
1181
1182	/*
1183	 * Check if the user asked us to deliver the result through an
1184	 * eventfd. The eventfd_signal() function is safe to be called
1185	 * from IRQ context.
1186	 */
1187	if (iocb->ki_eventfd)
1188		eventfd_signal(iocb->ki_eventfd);
 
 
 
1189
1190	/*
1191	 * We have to order our ring_info tail store above and test
1192	 * of the wait list below outside the wait lock.  This is
1193	 * like in wake_up_bit() where clearing a bit has to be
1194	 * ordered with the unlocked test.
1195	 */
1196	smp_mb();
1197
1198	if (waitqueue_active(&ctx->wait)) {
1199		struct aio_waiter *curr, *next;
1200		unsigned long flags;
1201
1202		spin_lock_irqsave(&ctx->wait.lock, flags);
1203		list_for_each_entry_safe(curr, next, &ctx->wait.head, w.entry)
1204			if (avail >= curr->min_nr) {
1205				list_del_init_careful(&curr->w.entry);
1206				wake_up_process(curr->w.private);
1207			}
1208		spin_unlock_irqrestore(&ctx->wait.lock, flags);
1209	}
1210}
1211
1212static inline void iocb_put(struct aio_kiocb *iocb)
1213{
1214	if (refcount_dec_and_test(&iocb->ki_refcnt)) {
1215		aio_complete(iocb);
1216		iocb_destroy(iocb);
1217	}
1218}
1219
1220/* aio_read_events_ring
1221 *	Pull an event off of the ioctx's event ring.  Returns the number of
1222 *	events fetched
1223 */
1224static long aio_read_events_ring(struct kioctx *ctx,
1225				 struct io_event __user *event, long nr)
1226{
1227	struct aio_ring *ring;
1228	unsigned head, tail, pos;
1229	long ret = 0;
1230	int copy_ret;
1231
1232	/*
1233	 * The mutex can block and wake us up and that will cause
1234	 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1235	 * and repeat. This should be rare enough that it doesn't cause
1236	 * peformance issues. See the comment in read_events() for more detail.
1237	 */
1238	sched_annotate_sleep();
1239	mutex_lock(&ctx->ring_lock);
1240
1241	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
1242	ring = page_address(ctx->ring_pages[0]);
1243	head = ring->head;
1244	tail = ring->tail;
 
1245
1246	/*
1247	 * Ensure that once we've read the current tail pointer, that
1248	 * we also see the events that were stored up to the tail.
1249	 */
1250	smp_rmb();
1251
1252	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1253
1254	if (head == tail)
1255		goto out;
1256
1257	head %= ctx->nr_events;
1258	tail %= ctx->nr_events;
1259
1260	while (ret < nr) {
1261		long avail;
1262		struct io_event *ev;
1263		struct page *page;
1264
1265		avail = (head <= tail ?  tail : ctx->nr_events) - head;
1266		if (head == tail)
1267			break;
1268
 
 
 
 
1269		pos = head + AIO_EVENTS_OFFSET;
1270		page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1271		pos %= AIO_EVENTS_PER_PAGE;
1272
1273		avail = min(avail, nr - ret);
1274		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1275
1276		ev = page_address(page);
1277		copy_ret = copy_to_user(event + ret, ev + pos,
1278					sizeof(*ev) * avail);
 
1279
1280		if (unlikely(copy_ret)) {
1281			ret = -EFAULT;
1282			goto out;
1283		}
1284
1285		ret += avail;
1286		head += avail;
1287		head %= ctx->nr_events;
1288	}
1289
1290	ring = page_address(ctx->ring_pages[0]);
1291	ring->head = head;
 
1292	flush_dcache_page(ctx->ring_pages[0]);
1293
1294	pr_debug("%li  h%u t%u\n", ret, head, tail);
1295out:
1296	mutex_unlock(&ctx->ring_lock);
1297
1298	return ret;
1299}
1300
1301static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1302			    struct io_event __user *event, long *i)
1303{
1304	long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1305
1306	if (ret > 0)
1307		*i += ret;
1308
1309	if (unlikely(atomic_read(&ctx->dead)))
1310		ret = -EINVAL;
1311
1312	if (!*i)
1313		*i = ret;
1314
1315	return ret < 0 || *i >= min_nr;
1316}
1317
1318static long read_events(struct kioctx *ctx, long min_nr, long nr,
1319			struct io_event __user *event,
1320			ktime_t until)
1321{
1322	struct hrtimer_sleeper	t;
1323	struct aio_waiter	w;
1324	long ret = 0, ret2 = 0;
 
 
 
 
 
 
 
 
1325
1326	/*
1327	 * Note that aio_read_events() is being called as the conditional - i.e.
1328	 * we're calling it after prepare_to_wait() has set task state to
1329	 * TASK_INTERRUPTIBLE.
1330	 *
1331	 * But aio_read_events() can block, and if it blocks it's going to flip
1332	 * the task state back to TASK_RUNNING.
1333	 *
1334	 * This should be ok, provided it doesn't flip the state back to
1335	 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1336	 * will only happen if the mutex_lock() call blocks, and we then find
1337	 * the ringbuffer empty. So in practice we should be ok, but it's
1338	 * something to be aware of when touching this code.
1339	 */
1340	aio_read_events(ctx, min_nr, nr, event, &ret);
1341	if (until == 0 || ret < 0 || ret >= min_nr)
1342		return ret;
1343
1344	hrtimer_init_sleeper_on_stack(&t, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1345	if (until != KTIME_MAX) {
1346		hrtimer_set_expires_range_ns(&t.timer, until, current->timer_slack_ns);
1347		hrtimer_sleeper_start_expires(&t, HRTIMER_MODE_REL);
1348	}
1349
1350	init_wait(&w.w);
1351
1352	while (1) {
1353		unsigned long nr_got = ret;
1354
1355		w.min_nr = min_nr - ret;
1356
1357		ret2 = prepare_to_wait_event(&ctx->wait, &w.w, TASK_INTERRUPTIBLE);
1358		if (!ret2 && !t.task)
1359			ret2 = -ETIME;
1360
1361		if (aio_read_events(ctx, min_nr, nr, event, &ret) || ret2)
1362			break;
1363
1364		if (nr_got == ret)
1365			schedule();
1366	}
1367
1368	finish_wait(&ctx->wait, &w.w);
1369	hrtimer_cancel(&t.timer);
1370	destroy_hrtimer_on_stack(&t.timer);
1371
1372	return ret;
1373}
1374
1375/* sys_io_setup:
1376 *	Create an aio_context capable of receiving at least nr_events.
1377 *	ctxp must not point to an aio_context that already exists, and
1378 *	must be initialized to 0 prior to the call.  On successful
1379 *	creation of the aio_context, *ctxp is filled in with the resulting 
1380 *	handle.  May fail with -EINVAL if *ctxp is not initialized,
1381 *	if the specified nr_events exceeds internal limits.  May fail 
1382 *	with -EAGAIN if the specified nr_events exceeds the user's limit 
1383 *	of available events.  May fail with -ENOMEM if insufficient kernel
1384 *	resources are available.  May fail with -EFAULT if an invalid
1385 *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
1386 *	implemented.
1387 */
1388SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1389{
1390	struct kioctx *ioctx = NULL;
1391	unsigned long ctx;
1392	long ret;
1393
1394	ret = get_user(ctx, ctxp);
1395	if (unlikely(ret))
1396		goto out;
1397
1398	ret = -EINVAL;
1399	if (unlikely(ctx || nr_events == 0)) {
1400		pr_debug("EINVAL: ctx %lu nr_events %u\n",
1401		         ctx, nr_events);
1402		goto out;
1403	}
1404
1405	ioctx = ioctx_alloc(nr_events);
1406	ret = PTR_ERR(ioctx);
1407	if (!IS_ERR(ioctx)) {
1408		ret = put_user(ioctx->user_id, ctxp);
1409		if (ret)
1410			kill_ioctx(current->mm, ioctx, NULL);
1411		percpu_ref_put(&ioctx->users);
1412	}
1413
1414out:
1415	return ret;
1416}
1417
1418#ifdef CONFIG_COMPAT
1419COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1420{
1421	struct kioctx *ioctx = NULL;
1422	unsigned long ctx;
1423	long ret;
1424
1425	ret = get_user(ctx, ctx32p);
1426	if (unlikely(ret))
1427		goto out;
1428
1429	ret = -EINVAL;
1430	if (unlikely(ctx || nr_events == 0)) {
1431		pr_debug("EINVAL: ctx %lu nr_events %u\n",
1432		         ctx, nr_events);
1433		goto out;
1434	}
1435
1436	ioctx = ioctx_alloc(nr_events);
1437	ret = PTR_ERR(ioctx);
1438	if (!IS_ERR(ioctx)) {
1439		/* truncating is ok because it's a user address */
1440		ret = put_user((u32)ioctx->user_id, ctx32p);
1441		if (ret)
1442			kill_ioctx(current->mm, ioctx, NULL);
1443		percpu_ref_put(&ioctx->users);
1444	}
1445
1446out:
1447	return ret;
1448}
1449#endif
1450
1451/* sys_io_destroy:
1452 *	Destroy the aio_context specified.  May cancel any outstanding 
1453 *	AIOs and block on completion.  Will fail with -ENOSYS if not
1454 *	implemented.  May fail with -EINVAL if the context pointed to
1455 *	is invalid.
1456 */
1457SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1458{
1459	struct kioctx *ioctx = lookup_ioctx(ctx);
1460	if (likely(NULL != ioctx)) {
1461		struct ctx_rq_wait wait;
1462		int ret;
1463
1464		init_completion(&wait.comp);
1465		atomic_set(&wait.count, 1);
1466
1467		/* Pass requests_done to kill_ioctx() where it can be set
1468		 * in a thread-safe way. If we try to set it here then we have
1469		 * a race condition if two io_destroy() called simultaneously.
1470		 */
1471		ret = kill_ioctx(current->mm, ioctx, &wait);
1472		percpu_ref_put(&ioctx->users);
1473
1474		/* Wait until all IO for the context are done. Otherwise kernel
1475		 * keep using user-space buffers even if user thinks the context
1476		 * is destroyed.
1477		 */
1478		if (!ret)
1479			wait_for_completion(&wait.comp);
1480
1481		return ret;
1482	}
1483	pr_debug("EINVAL: invalid context id\n");
1484	return -EINVAL;
1485}
1486
1487static void aio_remove_iocb(struct aio_kiocb *iocb)
1488{
1489	struct kioctx *ctx = iocb->ki_ctx;
1490	unsigned long flags;
1491
1492	spin_lock_irqsave(&ctx->ctx_lock, flags);
1493	list_del(&iocb->ki_list);
1494	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1495}
1496
1497static void aio_complete_rw(struct kiocb *kiocb, long res)
1498{
1499	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1500
1501	if (!list_empty_careful(&iocb->ki_list))
1502		aio_remove_iocb(iocb);
1503
1504	if (kiocb->ki_flags & IOCB_WRITE) {
1505		struct inode *inode = file_inode(kiocb->ki_filp);
1506
1507		if (S_ISREG(inode->i_mode))
1508			kiocb_end_write(kiocb);
1509	}
1510
1511	iocb->ki_res.res = res;
1512	iocb->ki_res.res2 = 0;
1513	iocb_put(iocb);
1514}
1515
1516static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
1517{
1518	int ret;
1519
1520	req->ki_complete = aio_complete_rw;
1521	req->private = NULL;
1522	req->ki_pos = iocb->aio_offset;
1523	req->ki_flags = req->ki_filp->f_iocb_flags | IOCB_AIO_RW;
1524	if (iocb->aio_flags & IOCB_FLAG_RESFD)
1525		req->ki_flags |= IOCB_EVENTFD;
1526	if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1527		/*
1528		 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1529		 * aio_reqprio is interpreted as an I/O scheduling
1530		 * class and priority.
1531		 */
1532		ret = ioprio_check_cap(iocb->aio_reqprio);
1533		if (ret) {
1534			pr_debug("aio ioprio check cap error: %d\n", ret);
1535			return ret;
1536		}
1537
1538		req->ki_ioprio = iocb->aio_reqprio;
1539	} else
1540		req->ki_ioprio = get_current_ioprio();
1541
1542	ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
1543	if (unlikely(ret))
1544		return ret;
1545
1546	req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1547	return 0;
1548}
1549
1550static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1551		struct iovec **iovec, bool vectored, bool compat,
1552		struct iov_iter *iter)
1553{
1554	void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1555	size_t len = iocb->aio_nbytes;
1556
1557	if (!vectored) {
1558		ssize_t ret = import_ubuf(rw, buf, len, iter);
1559		*iovec = NULL;
1560		return ret;
1561	}
1562
1563	return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
1564}
1565
1566static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1567{
1568	switch (ret) {
1569	case -EIOCBQUEUED:
1570		break;
1571	case -ERESTARTSYS:
1572	case -ERESTARTNOINTR:
1573	case -ERESTARTNOHAND:
1574	case -ERESTART_RESTARTBLOCK:
1575		/*
1576		 * There's no easy way to restart the syscall since other AIO's
1577		 * may be already running. Just fail this IO with EINTR.
1578		 */
1579		ret = -EINTR;
1580		fallthrough;
1581	default:
1582		req->ki_complete(req, ret);
1583	}
1584}
1585
1586static int aio_read(struct kiocb *req, const struct iocb *iocb,
1587			bool vectored, bool compat)
1588{
1589	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1590	struct iov_iter iter;
1591	struct file *file;
1592	int ret;
1593
1594	ret = aio_prep_rw(req, iocb);
1595	if (ret)
1596		return ret;
1597	file = req->ki_filp;
1598	if (unlikely(!(file->f_mode & FMODE_READ)))
1599		return -EBADF;
1600	if (unlikely(!file->f_op->read_iter))
1601		return -EINVAL;
1602
1603	ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
1604	if (ret < 0)
1605		return ret;
1606	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1607	if (!ret)
1608		aio_rw_done(req, call_read_iter(file, req, &iter));
1609	kfree(iovec);
1610	return ret;
1611}
1612
1613static int aio_write(struct kiocb *req, const struct iocb *iocb,
1614			 bool vectored, bool compat)
1615{
1616	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1617	struct iov_iter iter;
1618	struct file *file;
1619	int ret;
1620
1621	ret = aio_prep_rw(req, iocb);
1622	if (ret)
1623		return ret;
1624	file = req->ki_filp;
1625
1626	if (unlikely(!(file->f_mode & FMODE_WRITE)))
1627		return -EBADF;
1628	if (unlikely(!file->f_op->write_iter))
1629		return -EINVAL;
1630
1631	ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
1632	if (ret < 0)
1633		return ret;
1634	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1635	if (!ret) {
1636		if (S_ISREG(file_inode(file)->i_mode))
1637			kiocb_start_write(req);
1638		req->ki_flags |= IOCB_WRITE;
1639		aio_rw_done(req, call_write_iter(file, req, &iter));
1640	}
1641	kfree(iovec);
1642	return ret;
1643}
1644
1645static void aio_fsync_work(struct work_struct *work)
1646{
1647	struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1648	const struct cred *old_cred = override_creds(iocb->fsync.creds);
1649
1650	iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
1651	revert_creds(old_cred);
1652	put_cred(iocb->fsync.creds);
1653	iocb_put(iocb);
1654}
1655
1656static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1657		     bool datasync)
1658{
1659	if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1660			iocb->aio_rw_flags))
1661		return -EINVAL;
1662
1663	if (unlikely(!req->file->f_op->fsync))
1664		return -EINVAL;
1665
1666	req->creds = prepare_creds();
1667	if (!req->creds)
1668		return -ENOMEM;
1669
1670	req->datasync = datasync;
1671	INIT_WORK(&req->work, aio_fsync_work);
1672	schedule_work(&req->work);
1673	return 0;
1674}
1675
1676static void aio_poll_put_work(struct work_struct *work)
 
 
 
1677{
1678	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1679	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1680
1681	iocb_put(iocb);
 
 
 
 
1682}
1683
1684/*
1685 * Safely lock the waitqueue which the request is on, synchronizing with the
1686 * case where the ->poll() provider decides to free its waitqueue early.
1687 *
1688 * Returns true on success, meaning that req->head->lock was locked, req->wait
1689 * is on req->head, and an RCU read lock was taken.  Returns false if the
1690 * request was already removed from its waitqueue (which might no longer exist).
1691 */
1692static bool poll_iocb_lock_wq(struct poll_iocb *req)
1693{
1694	wait_queue_head_t *head;
1695
1696	/*
1697	 * While we hold the waitqueue lock and the waitqueue is nonempty,
1698	 * wake_up_pollfree() will wait for us.  However, taking the waitqueue
1699	 * lock in the first place can race with the waitqueue being freed.
1700	 *
1701	 * We solve this as eventpoll does: by taking advantage of the fact that
1702	 * all users of wake_up_pollfree() will RCU-delay the actual free.  If
1703	 * we enter rcu_read_lock() and see that the pointer to the queue is
1704	 * non-NULL, we can then lock it without the memory being freed out from
1705	 * under us, then check whether the request is still on the queue.
1706	 *
1707	 * Keep holding rcu_read_lock() as long as we hold the queue lock, in
1708	 * case the caller deletes the entry from the queue, leaving it empty.
1709	 * In that case, only RCU prevents the queue memory from being freed.
1710	 */
1711	rcu_read_lock();
1712	head = smp_load_acquire(&req->head);
1713	if (head) {
1714		spin_lock(&head->lock);
1715		if (!list_empty(&req->wait.entry))
1716			return true;
1717		spin_unlock(&head->lock);
1718	}
1719	rcu_read_unlock();
1720	return false;
1721}
1722
1723static void poll_iocb_unlock_wq(struct poll_iocb *req)
1724{
1725	spin_unlock(&req->head->lock);
1726	rcu_read_unlock();
1727}
1728
1729static void aio_poll_complete_work(struct work_struct *work)
1730{
1731	struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1732	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1733	struct poll_table_struct pt = { ._key = req->events };
1734	struct kioctx *ctx = iocb->ki_ctx;
1735	__poll_t mask = 0;
 
 
1736
1737	if (!READ_ONCE(req->cancelled))
1738		mask = vfs_poll(req->file, &pt) & req->events;
 
 
 
 
 
1739
1740	/*
1741	 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1742	 * calling ->ki_cancel.  We need the ctx_lock roundtrip here to
1743	 * synchronize with them.  In the cancellation case the list_del_init
1744	 * itself is not actually needed, but harmless so we keep it in to
1745	 * avoid further branches in the fast path.
1746	 */
1747	spin_lock_irq(&ctx->ctx_lock);
1748	if (poll_iocb_lock_wq(req)) {
1749		if (!mask && !READ_ONCE(req->cancelled)) {
1750			/*
1751			 * The request isn't actually ready to be completed yet.
1752			 * Reschedule completion if another wakeup came in.
1753			 */
1754			if (req->work_need_resched) {
1755				schedule_work(&req->work);
1756				req->work_need_resched = false;
1757			} else {
1758				req->work_scheduled = false;
1759			}
1760			poll_iocb_unlock_wq(req);
1761			spin_unlock_irq(&ctx->ctx_lock);
1762			return;
1763		}
1764		list_del_init(&req->wait.entry);
1765		poll_iocb_unlock_wq(req);
1766	} /* else, POLLFREE has freed the waitqueue, so we must complete */
1767	list_del_init(&iocb->ki_list);
1768	iocb->ki_res.res = mangle_poll(mask);
1769	spin_unlock_irq(&ctx->ctx_lock);
1770
1771	iocb_put(iocb);
1772}
1773
1774/* assumes we are called with irqs disabled */
1775static int aio_poll_cancel(struct kiocb *iocb)
1776{
1777	struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1778	struct poll_iocb *req = &aiocb->poll;
1779
1780	if (poll_iocb_lock_wq(req)) {
1781		WRITE_ONCE(req->cancelled, true);
1782		if (!req->work_scheduled) {
1783			schedule_work(&aiocb->poll.work);
1784			req->work_scheduled = true;
1785		}
1786		poll_iocb_unlock_wq(req);
1787	} /* else, the request was force-cancelled by POLLFREE already */
1788
1789	return 0;
1790}
1791
1792static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1793		void *key)
1794{
1795	struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1796	struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1797	__poll_t mask = key_to_poll(key);
1798	unsigned long flags;
1799
1800	/* for instances that support it check for an event match first: */
1801	if (mask && !(mask & req->events))
1802		return 0;
1803
1804	/*
1805	 * Complete the request inline if possible.  This requires that three
1806	 * conditions be met:
1807	 *   1. An event mask must have been passed.  If a plain wakeup was done
1808	 *	instead, then mask == 0 and we have to call vfs_poll() to get
1809	 *	the events, so inline completion isn't possible.
1810	 *   2. The completion work must not have already been scheduled.
1811	 *   3. ctx_lock must not be busy.  We have to use trylock because we
1812	 *	already hold the waitqueue lock, so this inverts the normal
1813	 *	locking order.  Use irqsave/irqrestore because not all
1814	 *	filesystems (e.g. fuse) call this function with IRQs disabled,
1815	 *	yet IRQs have to be disabled before ctx_lock is obtained.
1816	 */
1817	if (mask && !req->work_scheduled &&
1818	    spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1819		struct kioctx *ctx = iocb->ki_ctx;
1820
1821		list_del_init(&req->wait.entry);
1822		list_del(&iocb->ki_list);
1823		iocb->ki_res.res = mangle_poll(mask);
1824		if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1825			iocb = NULL;
1826			INIT_WORK(&req->work, aio_poll_put_work);
1827			schedule_work(&req->work);
1828		}
1829		spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1830		if (iocb)
1831			iocb_put(iocb);
1832	} else {
1833		/*
1834		 * Schedule the completion work if needed.  If it was already
1835		 * scheduled, record that another wakeup came in.
1836		 *
1837		 * Don't remove the request from the waitqueue here, as it might
1838		 * not actually be complete yet (we won't know until vfs_poll()
1839		 * is called), and we must not miss any wakeups.  POLLFREE is an
1840		 * exception to this; see below.
1841		 */
1842		if (req->work_scheduled) {
1843			req->work_need_resched = true;
1844		} else {
1845			schedule_work(&req->work);
1846			req->work_scheduled = true;
1847		}
1848
1849		/*
1850		 * If the waitqueue is being freed early but we can't complete
1851		 * the request inline, we have to tear down the request as best
1852		 * we can.  That means immediately removing the request from its
1853		 * waitqueue and preventing all further accesses to the
1854		 * waitqueue via the request.  We also need to schedule the
1855		 * completion work (done above).  Also mark the request as
1856		 * cancelled, to potentially skip an unneeded call to ->poll().
1857		 */
1858		if (mask & POLLFREE) {
1859			WRITE_ONCE(req->cancelled, true);
1860			list_del_init(&req->wait.entry);
1861
1862			/*
1863			 * Careful: this *must* be the last step, since as soon
1864			 * as req->head is NULL'ed out, the request can be
1865			 * completed and freed, since aio_poll_complete_work()
1866			 * will no longer need to take the waitqueue lock.
1867			 */
1868			smp_store_release(&req->head, NULL);
1869		}
1870	}
1871	return 1;
1872}
1873
1874struct aio_poll_table {
1875	struct poll_table_struct	pt;
1876	struct aio_kiocb		*iocb;
1877	bool				queued;
1878	int				error;
1879};
1880
1881static void
1882aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1883		struct poll_table_struct *p)
1884{
1885	struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1886
1887	/* multiple wait queues per file are not supported */
1888	if (unlikely(pt->queued)) {
1889		pt->error = -EINVAL;
1890		return;
1891	}
1892
1893	pt->queued = true;
1894	pt->error = 0;
1895	pt->iocb->poll.head = head;
1896	add_wait_queue(head, &pt->iocb->poll.wait);
1897}
1898
1899static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1900{
1901	struct kioctx *ctx = aiocb->ki_ctx;
1902	struct poll_iocb *req = &aiocb->poll;
1903	struct aio_poll_table apt;
1904	bool cancel = false;
1905	__poll_t mask;
1906
1907	/* reject any unknown events outside the normal event mask. */
1908	if ((u16)iocb->aio_buf != iocb->aio_buf)
1909		return -EINVAL;
1910	/* reject fields that are not defined for poll */
1911	if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1912		return -EINVAL;
1913
1914	INIT_WORK(&req->work, aio_poll_complete_work);
1915	req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1916
1917	req->head = NULL;
1918	req->cancelled = false;
1919	req->work_scheduled = false;
1920	req->work_need_resched = false;
1921
1922	apt.pt._qproc = aio_poll_queue_proc;
1923	apt.pt._key = req->events;
1924	apt.iocb = aiocb;
1925	apt.queued = false;
1926	apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1927
1928	/* initialized the list so that we can do list_empty checks */
1929	INIT_LIST_HEAD(&req->wait.entry);
1930	init_waitqueue_func_entry(&req->wait, aio_poll_wake);
1931
1932	mask = vfs_poll(req->file, &apt.pt) & req->events;
1933	spin_lock_irq(&ctx->ctx_lock);
1934	if (likely(apt.queued)) {
1935		bool on_queue = poll_iocb_lock_wq(req);
1936
1937		if (!on_queue || req->work_scheduled) {
1938			/*
1939			 * aio_poll_wake() already either scheduled the async
1940			 * completion work, or completed the request inline.
1941			 */
1942			if (apt.error) /* unsupported case: multiple queues */
1943				cancel = true;
1944			apt.error = 0;
1945			mask = 0;
1946		}
1947		if (mask || apt.error) {
1948			/* Steal to complete synchronously. */
1949			list_del_init(&req->wait.entry);
1950		} else if (cancel) {
1951			/* Cancel if possible (may be too late though). */
1952			WRITE_ONCE(req->cancelled, true);
1953		} else if (on_queue) {
1954			/*
1955			 * Actually waiting for an event, so add the request to
1956			 * active_reqs so that it can be cancelled if needed.
1957			 */
1958			list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
1959			aiocb->ki_cancel = aio_poll_cancel;
1960		}
1961		if (on_queue)
1962			poll_iocb_unlock_wq(req);
1963	}
1964	if (mask) { /* no async, we'd stolen it */
1965		aiocb->ki_res.res = mangle_poll(mask);
1966		apt.error = 0;
1967	}
1968	spin_unlock_irq(&ctx->ctx_lock);
1969	if (mask)
1970		iocb_put(aiocb);
1971	return apt.error;
1972}
1973
1974static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1975			   struct iocb __user *user_iocb, struct aio_kiocb *req,
1976			   bool compat)
1977{
1978	req->ki_filp = fget(iocb->aio_fildes);
1979	if (unlikely(!req->ki_filp))
1980		return -EBADF;
1981
1982	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1983		struct eventfd_ctx *eventfd;
1984		/*
1985		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1986		 * instance of the file* now. The file descriptor must be
1987		 * an eventfd() fd, and will be signaled for each completed
1988		 * event using the eventfd_signal() function.
1989		 */
1990		eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
1991		if (IS_ERR(eventfd))
1992			return PTR_ERR(eventfd);
1993
1994		req->ki_eventfd = eventfd;
1995	}
1996
1997	if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1998		pr_debug("EFAULT: aio_key\n");
1999		return -EFAULT;
2000	}
2001
2002	req->ki_res.obj = (u64)(unsigned long)user_iocb;
2003	req->ki_res.data = iocb->aio_data;
2004	req->ki_res.res = 0;
2005	req->ki_res.res2 = 0;
2006
2007	switch (iocb->aio_lio_opcode) {
2008	case IOCB_CMD_PREAD:
2009		return aio_read(&req->rw, iocb, false, compat);
2010	case IOCB_CMD_PWRITE:
2011		return aio_write(&req->rw, iocb, false, compat);
2012	case IOCB_CMD_PREADV:
2013		return aio_read(&req->rw, iocb, true, compat);
2014	case IOCB_CMD_PWRITEV:
2015		return aio_write(&req->rw, iocb, true, compat);
2016	case IOCB_CMD_FSYNC:
2017		return aio_fsync(&req->fsync, iocb, false);
2018	case IOCB_CMD_FDSYNC:
2019		return aio_fsync(&req->fsync, iocb, true);
2020	case IOCB_CMD_POLL:
2021		return aio_poll(req, iocb);
2022	default:
2023		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
2024		return -EINVAL;
2025	}
2026}
2027
2028static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
2029			 bool compat)
2030{
2031	struct aio_kiocb *req;
2032	struct iocb iocb;
2033	int err;
2034
2035	if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
2036		return -EFAULT;
2037
2038	/* enforce forwards compatibility on users */
2039	if (unlikely(iocb.aio_reserved2)) {
2040		pr_debug("EINVAL: reserve field set\n");
2041		return -EINVAL;
2042	}
2043
2044	/* prevent overflows */
2045	if (unlikely(
2046	    (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
2047	    (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
2048	    ((ssize_t)iocb.aio_nbytes < 0)
2049	   )) {
2050		pr_debug("EINVAL: overflow check\n");
2051		return -EINVAL;
2052	}
2053
2054	req = aio_get_req(ctx);
2055	if (unlikely(!req))
2056		return -EAGAIN;
2057
2058	err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2059
2060	/* Done with the synchronous reference */
2061	iocb_put(req);
2062
2063	/*
2064	 * If err is 0, we'd either done aio_complete() ourselves or have
2065	 * arranged for that to be done asynchronously.  Anything non-zero
2066	 * means that we need to destroy req ourselves.
2067	 */
2068	if (unlikely(err)) {
2069		iocb_destroy(req);
2070		put_reqs_available(ctx, 1);
2071	}
2072	return err;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2073}
2074
2075/* sys_io_submit:
2076 *	Queue the nr iocbs pointed to by iocbpp for processing.  Returns
2077 *	the number of iocbs queued.  May return -EINVAL if the aio_context
2078 *	specified by ctx_id is invalid, if nr is < 0, if the iocb at
2079 *	*iocbpp[0] is not properly initialized, if the operation specified
2080 *	is invalid for the file descriptor in the iocb.  May fail with
2081 *	-EFAULT if any of the data structures point to invalid data.  May
2082 *	fail with -EBADF if the file descriptor specified in the first
2083 *	iocb is invalid.  May fail with -EAGAIN if insufficient resources
2084 *	are available to queue any iocbs.  Will return 0 if nr is 0.  Will
2085 *	fail with -ENOSYS if not implemented.
2086 */
2087SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2088		struct iocb __user * __user *, iocbpp)
2089{
2090	struct kioctx *ctx;
2091	long ret = 0;
2092	int i = 0;
2093	struct blk_plug plug;
2094
2095	if (unlikely(nr < 0))
2096		return -EINVAL;
2097
 
 
 
 
 
 
2098	ctx = lookup_ioctx(ctx_id);
2099	if (unlikely(!ctx)) {
2100		pr_debug("EINVAL: invalid context id\n");
2101		return -EINVAL;
2102	}
2103
2104	if (nr > ctx->nr_events)
2105		nr = ctx->nr_events;
2106
2107	if (nr > AIO_PLUG_THRESHOLD)
2108		blk_start_plug(&plug);
2109	for (i = 0; i < nr; i++) {
 
 
2110		struct iocb __user *user_iocb;
 
 
 
 
 
 
2111
2112		if (unlikely(get_user(user_iocb, iocbpp + i))) {
2113			ret = -EFAULT;
2114			break;
2115		}
2116
2117		ret = io_submit_one(ctx, user_iocb, false);
2118		if (ret)
2119			break;
2120	}
2121	if (nr > AIO_PLUG_THRESHOLD)
2122		blk_finish_plug(&plug);
2123
2124	percpu_ref_put(&ctx->users);
2125	return i ? i : ret;
2126}
2127
2128#ifdef CONFIG_COMPAT
2129COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2130		       int, nr, compat_uptr_t __user *, iocbpp)
 
 
 
 
 
 
 
 
 
 
 
2131{
2132	struct kioctx *ctx;
2133	long ret = 0;
2134	int i = 0;
2135	struct blk_plug plug;
2136
2137	if (unlikely(nr < 0))
2138		return -EINVAL;
2139
2140	ctx = lookup_ioctx(ctx_id);
2141	if (unlikely(!ctx)) {
2142		pr_debug("EINVAL: invalid context id\n");
2143		return -EINVAL;
2144	}
2145
2146	if (nr > ctx->nr_events)
2147		nr = ctx->nr_events;
 
 
 
 
 
2148
2149	if (nr > AIO_PLUG_THRESHOLD)
2150		blk_start_plug(&plug);
2151	for (i = 0; i < nr; i++) {
2152		compat_uptr_t user_iocb;
2153
2154		if (unlikely(get_user(user_iocb, iocbpp + i))) {
2155			ret = -EFAULT;
2156			break;
2157		}
2158
2159		ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
2160		if (ret)
2161			break;
 
2162	}
2163	if (nr > AIO_PLUG_THRESHOLD)
2164		blk_finish_plug(&plug);
2165
2166	percpu_ref_put(&ctx->users);
2167	return i ? i : ret;
2168}
2169#endif
2170
2171/* sys_io_cancel:
2172 *	Attempts to cancel an iocb previously passed to io_submit.  If
2173 *	the operation is successfully cancelled, the resulting event is
2174 *	copied into the memory pointed to by result without being placed
2175 *	into the completion queue and 0 is returned.  May fail with
2176 *	-EFAULT if any of the data structures pointed to are invalid.
2177 *	May fail with -EINVAL if aio_context specified by ctx_id is
2178 *	invalid.  May fail with -EAGAIN if the iocb specified was not
2179 *	cancelled.  Will fail with -ENOSYS if not implemented.
2180 */
2181SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2182		struct io_event __user *, result)
2183{
2184	struct kioctx *ctx;
2185	struct aio_kiocb *kiocb;
2186	int ret = -EINVAL;
2187	u32 key;
2188	u64 obj = (u64)(unsigned long)iocb;
2189
2190	if (unlikely(get_user(key, &iocb->aio_key)))
 
2191		return -EFAULT;
2192	if (unlikely(key != KIOCB_KEY))
2193		return -EINVAL;
2194
2195	ctx = lookup_ioctx(ctx_id);
2196	if (unlikely(!ctx))
2197		return -EINVAL;
2198
2199	spin_lock_irq(&ctx->ctx_lock);
2200	/* TODO: use a hash or array, this sucks. */
2201	list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2202		if (kiocb->ki_res.obj == obj) {
2203			ret = kiocb->ki_cancel(&kiocb->rw);
2204			list_del_init(&kiocb->ki_list);
2205			break;
2206		}
2207	}
2208	spin_unlock_irq(&ctx->ctx_lock);
2209
2210	if (!ret) {
2211		/*
2212		 * The result argument is no longer used - the io_event is
2213		 * always delivered via the ring buffer. -EINPROGRESS indicates
2214		 * cancellation is progress:
2215		 */
2216		ret = -EINPROGRESS;
2217	}
2218
2219	percpu_ref_put(&ctx->users);
2220
2221	return ret;
2222}
2223
2224static long do_io_getevents(aio_context_t ctx_id,
2225		long min_nr,
2226		long nr,
2227		struct io_event __user *events,
2228		struct timespec64 *ts)
2229{
2230	ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
2231	struct kioctx *ioctx = lookup_ioctx(ctx_id);
2232	long ret = -EINVAL;
2233
2234	if (likely(ioctx)) {
2235		if (likely(min_nr <= nr && min_nr >= 0))
2236			ret = read_events(ioctx, min_nr, nr, events, until);
2237		percpu_ref_put(&ioctx->users);
2238	}
2239
2240	return ret;
2241}
2242
2243/* io_getevents:
2244 *	Attempts to read at least min_nr events and up to nr events from
2245 *	the completion queue for the aio_context specified by ctx_id. If
2246 *	it succeeds, the number of read events is returned. May fail with
2247 *	-EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2248 *	out of range, if timeout is out of range.  May fail with -EFAULT
2249 *	if any of the memory specified is invalid.  May return 0 or
2250 *	< min_nr if the timeout specified by timeout has elapsed
2251 *	before sufficient events are available, where timeout == NULL
2252 *	specifies an infinite timeout. Note that the timeout pointed to by
2253 *	timeout is relative.  Will fail with -ENOSYS if not implemented.
2254 */
2255#ifdef CONFIG_64BIT
2256
2257SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2258		long, min_nr,
2259		long, nr,
2260		struct io_event __user *, events,
2261		struct __kernel_timespec __user *, timeout)
2262{
2263	struct timespec64	ts;
2264	int			ret;
2265
2266	if (timeout && unlikely(get_timespec64(&ts, timeout)))
2267		return -EFAULT;
2268
2269	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2270	if (!ret && signal_pending(current))
2271		ret = -EINTR;
2272	return ret;
2273}
2274
2275#endif
2276
2277struct __aio_sigset {
2278	const sigset_t __user	*sigmask;
2279	size_t		sigsetsize;
2280};
2281
2282SYSCALL_DEFINE6(io_pgetevents,
2283		aio_context_t, ctx_id,
2284		long, min_nr,
2285		long, nr,
2286		struct io_event __user *, events,
2287		struct __kernel_timespec __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_timespec64(&ts, timeout)))
2296		return -EFAULT;
2297
2298	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2299		return -EFAULT;
2300
2301	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2302	if (ret)
2303		return ret;
2304
2305	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2306
2307	interrupted = signal_pending(current);
2308	restore_saved_sigmask_unless(interrupted);
2309	if (interrupted && !ret)
2310		ret = -ERESTARTNOHAND;
2311
2312	return ret;
2313}
2314
2315#if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2316
2317SYSCALL_DEFINE6(io_pgetevents_time32,
2318		aio_context_t, ctx_id,
2319		long, min_nr,
2320		long, nr,
2321		struct io_event __user *, events,
2322		struct old_timespec32 __user *, timeout,
2323		const struct __aio_sigset __user *, usig)
2324{
2325	struct __aio_sigset	ksig = { NULL, };
2326	struct timespec64	ts;
2327	bool interrupted;
2328	int ret;
2329
2330	if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2331		return -EFAULT;
2332
2333	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2334		return -EFAULT;
2335
2336
2337	ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2338	if (ret)
2339		return ret;
2340
2341	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2342
2343	interrupted = signal_pending(current);
2344	restore_saved_sigmask_unless(interrupted);
2345	if (interrupted && !ret)
2346		ret = -ERESTARTNOHAND;
2347
2348	return ret;
2349}
2350
2351#endif
2352
2353#if defined(CONFIG_COMPAT_32BIT_TIME)
2354
2355SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2356		__s32, min_nr,
2357		__s32, nr,
2358		struct io_event __user *, events,
2359		struct old_timespec32 __user *, timeout)
2360{
2361	struct timespec64 t;
2362	int ret;
2363
2364	if (timeout && get_old_timespec32(&t, timeout))
2365		return -EFAULT;
2366
2367	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2368	if (!ret && signal_pending(current))
2369		ret = -EINTR;
2370	return ret;
2371}
2372
2373#endif
2374
2375#ifdef CONFIG_COMPAT
2376
2377struct __compat_aio_sigset {
2378	compat_uptr_t		sigmask;
2379	compat_size_t		sigsetsize;
2380};
2381
2382#if defined(CONFIG_COMPAT_32BIT_TIME)
2383
2384COMPAT_SYSCALL_DEFINE6(io_pgetevents,
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 old_timespec32 __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_old_timespec32(&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
2417#endif
2418
2419COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2420		compat_aio_context_t, ctx_id,
2421		compat_long_t, min_nr,
2422		compat_long_t, nr,
2423		struct io_event __user *, events,
2424		struct __kernel_timespec __user *, timeout,
2425		const struct __compat_aio_sigset __user *, usig)
2426{
2427	struct __compat_aio_sigset ksig = { 0, };
2428	struct timespec64 t;
2429	bool interrupted;
2430	int ret;
2431
2432	if (timeout && get_timespec64(&t, timeout))
2433		return -EFAULT;
2434
2435	if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2436		return -EFAULT;
2437
2438	ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2439	if (ret)
2440		return ret;
2441
2442	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2443
2444	interrupted = signal_pending(current);
2445	restore_saved_sigmask_unless(interrupted);
2446	if (interrupted && !ret)
2447		ret = -ERESTARTNOHAND;
2448
 
 
 
 
 
2449	return ret;
2450}
2451#endif