Linux Audio

Check our new training course

Loading...
v3.1
   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 *
   9 *	See ../COPYING for licensing terms.
  10 */
 
 
  11#include <linux/kernel.h>
  12#include <linux/init.h>
  13#include <linux/errno.h>
  14#include <linux/time.h>
  15#include <linux/aio_abi.h>
  16#include <linux/module.h>
  17#include <linux/syscalls.h>
  18#include <linux/backing-dev.h>
 
  19#include <linux/uio.h>
  20
  21#define DEBUG 0
  22
  23#include <linux/sched.h>
  24#include <linux/fs.h>
  25#include <linux/file.h>
  26#include <linux/mm.h>
  27#include <linux/mman.h>
  28#include <linux/mmu_context.h>
  29#include <linux/slab.h>
  30#include <linux/timer.h>
  31#include <linux/aio.h>
  32#include <linux/highmem.h>
  33#include <linux/workqueue.h>
  34#include <linux/security.h>
  35#include <linux/eventfd.h>
  36#include <linux/blkdev.h>
  37#include <linux/compat.h>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  38
  39#include <asm/kmap_types.h>
  40#include <asm/uaccess.h>
  41
  42#if DEBUG > 1
  43#define dprintk		printk
  44#else
  45#define dprintk(x...)	do { ; } while (0)
  46#endif
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  47
  48/*------ sysctl variables----*/
  49static DEFINE_SPINLOCK(aio_nr_lock);
  50unsigned long aio_nr;		/* current system wide number of aio requests */
  51unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
  52/*----end sysctl variables---*/
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  53
  54static struct kmem_cache	*kiocb_cachep;
  55static struct kmem_cache	*kioctx_cachep;
  56
  57static struct workqueue_struct *aio_wq;
  58
  59/* Used for rare fput completion. */
  60static void aio_fput_routine(struct work_struct *);
  61static DECLARE_WORK(fput_work, aio_fput_routine);
  62
  63static DEFINE_SPINLOCK(fput_lock);
  64static LIST_HEAD(fput_head);
  65
  66static void aio_kick_handler(struct work_struct *);
  67static void aio_queue_work(struct kioctx *);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  68
  69/* aio_setup
  70 *	Creates the slab caches used by the aio routines, panic on
  71 *	failure as this is done early during the boot sequence.
  72 */
  73static int __init aio_setup(void)
  74{
  75	kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 
 
 
 
 
 
 
 
 
  76	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 
 
 
 
 
 
 
 
 
  77
  78	aio_wq = alloc_workqueue("aio", 0, 1);	/* used to limit concurrency */
  79	BUG_ON(!aio_wq);
  80
  81	pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page));
 
 
 
 
 
  82
  83	return 0;
 
  84}
  85__initcall(aio_setup);
  86
  87static void aio_free_ring(struct kioctx *ctx)
  88{
  89	struct aio_ring_info *info = &ctx->ring_info;
  90	long i;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  91
  92	for (i=0; i<info->nr_pages; i++)
  93		put_page(info->ring_pages[i]);
 
  94
  95	if (info->mmap_size) {
  96		down_write(&ctx->mm->mmap_sem);
  97		do_munmap(ctx->mm, info->mmap_base, info->mmap_size);
  98		up_write(&ctx->mm->mmap_sem);
  99	}
 100
 101	if (info->ring_pages && info->ring_pages != info->internal_pages)
 102		kfree(info->ring_pages);
 103	info->ring_pages = NULL;
 104	info->nr = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 105}
 
 
 
 
 
 
 
 
 106
 107static int aio_setup_ring(struct kioctx *ctx)
 108{
 109	struct aio_ring *ring;
 110	struct aio_ring_info *info = &ctx->ring_info;
 111	unsigned nr_events = ctx->max_reqs;
 112	unsigned long size;
 113	int nr_pages;
 
 
 114
 115	/* Compensate for the ring buffer's head/tail overlap entry */
 116	nr_events += 2;	/* 1 is required, 2 for good luck */
 117
 118	size = sizeof(struct aio_ring);
 119	size += sizeof(struct io_event) * nr_events;
 120	nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT;
 121
 
 122	if (nr_pages < 0)
 123		return -EINVAL;
 124
 125	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event);
 
 
 
 
 126
 127	info->nr = 0;
 128	info->ring_pages = info->internal_pages;
 
 
 
 129	if (nr_pages > AIO_RING_PAGES) {
 130		info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
 131		if (!info->ring_pages)
 
 
 132			return -ENOMEM;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 133	}
 
 134
 135	info->mmap_size = nr_pages * PAGE_SIZE;
 136	dprintk("attempting mmap of %lu bytes\n", info->mmap_size);
 137	down_write(&ctx->mm->mmap_sem);
 138	info->mmap_base = do_mmap(NULL, 0, info->mmap_size, 
 139				  PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE,
 140				  0);
 141	if (IS_ERR((void *)info->mmap_base)) {
 142		up_write(&ctx->mm->mmap_sem);
 143		info->mmap_size = 0;
 144		aio_free_ring(ctx);
 145		return -EAGAIN;
 146	}
 147
 148	dprintk("mmap address: 0x%08lx\n", info->mmap_base);
 149	info->nr_pages = get_user_pages(current, ctx->mm,
 150					info->mmap_base, nr_pages, 
 151					1, 0, info->ring_pages, NULL);
 152	up_write(&ctx->mm->mmap_sem);
 153
 154	if (unlikely(info->nr_pages != nr_pages)) {
 
 155		aio_free_ring(ctx);
 156		return -EAGAIN;
 157	}
 158
 159	ctx->user_id = info->mmap_base;
 
 
 
 
 
 
 
 
 160
 161	info->nr = nr_events;		/* trusted copy */
 162
 163	ring = kmap_atomic(info->ring_pages[0], KM_USER0);
 
 
 
 164	ring->nr = nr_events;	/* user copy */
 165	ring->id = ctx->user_id;
 166	ring->head = ring->tail = 0;
 167	ring->magic = AIO_RING_MAGIC;
 168	ring->compat_features = AIO_RING_COMPAT_FEATURES;
 169	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
 170	ring->header_length = sizeof(struct aio_ring);
 171	kunmap_atomic(ring, KM_USER0);
 172
 173	return 0;
 174}
 175
 176
 177/* aio_ring_event: returns a pointer to the event at the given index from
 178 * kmap_atomic(, km).  Release the pointer with put_aio_ring_event();
 179 */
 180#define AIO_EVENTS_PER_PAGE	(PAGE_SIZE / sizeof(struct io_event))
 181#define AIO_EVENTS_FIRST_PAGE	((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
 182#define AIO_EVENTS_OFFSET	(AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
 183
 184#define aio_ring_event(info, nr, km) ({					\
 185	unsigned pos = (nr) + AIO_EVENTS_OFFSET;			\
 186	struct io_event *__event;					\
 187	__event = kmap_atomic(						\
 188			(info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \
 189	__event += pos % AIO_EVENTS_PER_PAGE;				\
 190	__event;							\
 191})
 192
 193#define put_aio_ring_event(event, km) do {	\
 194	struct io_event *__event = (event);	\
 195	(void)__event;				\
 196	kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \
 197} while(0)
 198
 199static void ctx_rcu_free(struct rcu_head *head)
 200{
 201	struct kioctx *ctx = container_of(head, struct kioctx, rcu_head);
 202	unsigned nr_events = ctx->max_reqs;
 
 203
 204	kmem_cache_free(kioctx_cachep, ctx);
 
 
 
 
 
 205
 206	if (nr_events) {
 207		spin_lock(&aio_nr_lock);
 208		BUG_ON(aio_nr - nr_events > aio_nr);
 209		aio_nr -= nr_events;
 210		spin_unlock(&aio_nr_lock);
 211	}
 
 
 
 
 
 212}
 
 213
 214/* __put_ioctx
 215 *	Called when the last user of an aio context has gone away,
 216 *	and the struct needs to be freed.
 217 */
 218static void __put_ioctx(struct kioctx *ctx)
 219{
 220	BUG_ON(ctx->reqs_active);
 
 
 
 221
 222	cancel_delayed_work(&ctx->wq);
 223	cancel_work_sync(&ctx->wq.work);
 224	aio_free_ring(ctx);
 225	mmdrop(ctx->mm);
 226	ctx->mm = NULL;
 227	pr_debug("__put_ioctx: freeing %p\n", ctx);
 228	call_rcu(&ctx->rcu_head, ctx_rcu_free);
 229}
 230
 231static inline void get_ioctx(struct kioctx *kioctx)
 232{
 233	BUG_ON(atomic_read(&kioctx->users) <= 0);
 234	atomic_inc(&kioctx->users);
 
 
 
 
 
 
 
 235}
 236
 237static inline int try_get_ioctx(struct kioctx *kioctx)
 
 
 
 
 
 238{
 239	return atomic_inc_not_zero(&kioctx->users);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 240}
 241
 242static inline void put_ioctx(struct kioctx *kioctx)
 243{
 244	BUG_ON(atomic_read(&kioctx->users) <= 0);
 245	if (unlikely(atomic_dec_and_test(&kioctx->users)))
 246		__put_ioctx(kioctx);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 247}
 248
 249/* ioctx_alloc
 250 *	Allocates and initializes an ioctx.  Returns an ERR_PTR if it failed.
 251 */
 252static struct kioctx *ioctx_alloc(unsigned nr_events)
 253{
 254	struct mm_struct *mm;
 255	struct kioctx *ctx;
 256	int did_sync = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 257
 258	/* Prevent overflows */
 259	if ((nr_events > (0x10000000U / sizeof(struct io_event))) ||
 260	    (nr_events > (0x10000000U / sizeof(struct kiocb)))) {
 261		pr_debug("ENOMEM: nr_events too high\n");
 262		return ERR_PTR(-EINVAL);
 263	}
 264
 265	if ((unsigned long)nr_events > aio_max_nr)
 266		return ERR_PTR(-EAGAIN);
 267
 268	ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
 269	if (!ctx)
 270		return ERR_PTR(-ENOMEM);
 271
 272	ctx->max_reqs = nr_events;
 273	mm = ctx->mm = current->mm;
 274	atomic_inc(&mm->mm_count);
 275
 276	atomic_set(&ctx->users, 1);
 277	spin_lock_init(&ctx->ctx_lock);
 278	spin_lock_init(&ctx->ring_info.ring_lock);
 
 
 
 
 279	init_waitqueue_head(&ctx->wait);
 280
 281	INIT_LIST_HEAD(&ctx->active_reqs);
 282	INIT_LIST_HEAD(&ctx->run_list);
 283	INIT_DELAYED_WORK(&ctx->wq, aio_kick_handler);
 284
 285	if (aio_setup_ring(ctx) < 0)
 286		goto out_freectx;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 287
 288	/* limit the number of system wide aios */
 289	do {
 290		spin_lock_bh(&aio_nr_lock);
 291		if (aio_nr + nr_events > aio_max_nr ||
 292		    aio_nr + nr_events < aio_nr)
 293			ctx->max_reqs = 0;
 294		else
 295			aio_nr += ctx->max_reqs;
 296		spin_unlock_bh(&aio_nr_lock);
 297		if (ctx->max_reqs || did_sync)
 298			break;
 299
 300		/* wait for rcu callbacks to have completed before giving up */
 301		synchronize_rcu();
 302		did_sync = 1;
 303		ctx->max_reqs = nr_events;
 304	} while (1);
 305
 306	if (ctx->max_reqs == 0)
 307		goto out_cleanup;
 
 308
 309	/* now link into global list. */
 310	spin_lock(&mm->ioctx_lock);
 311	hlist_add_head_rcu(&ctx->list, &mm->ioctx_list);
 312	spin_unlock(&mm->ioctx_lock);
 313
 314	dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
 315		ctx, ctx->user_id, current->mm, ctx->ring_info.nr);
 316	return ctx;
 317
 318out_cleanup:
 319	__put_ioctx(ctx);
 320	return ERR_PTR(-EAGAIN);
 321
 322out_freectx:
 323	mmdrop(mm);
 
 
 
 
 
 
 324	kmem_cache_free(kioctx_cachep, ctx);
 325	ctx = ERR_PTR(-ENOMEM);
 326
 327	dprintk("aio: error allocating ioctx %p\n", ctx);
 328	return ctx;
 329}
 330
 331/* aio_cancel_all
 332 *	Cancels all outstanding aio requests on an aio context.  Used 
 333 *	when the processes owning a context have all exited to encourage 
 334 *	the rapid destruction of the kioctx.
 335 */
 336static void aio_cancel_all(struct kioctx *ctx)
 
 337{
 338	int (*cancel)(struct kiocb *, struct io_event *);
 339	struct io_event res;
 340	spin_lock_irq(&ctx->ctx_lock);
 341	ctx->dead = 1;
 342	while (!list_empty(&ctx->active_reqs)) {
 343		struct list_head *pos = ctx->active_reqs.next;
 344		struct kiocb *iocb = list_kiocb(pos);
 345		list_del_init(&iocb->ki_list);
 346		cancel = iocb->ki_cancel;
 347		kiocbSetCancelled(iocb);
 348		if (cancel) {
 349			iocb->ki_users++;
 350			spin_unlock_irq(&ctx->ctx_lock);
 351			cancel(iocb, &res);
 352			spin_lock_irq(&ctx->ctx_lock);
 353		}
 354	}
 355	spin_unlock_irq(&ctx->ctx_lock);
 356}
 357
 358static void wait_for_all_aios(struct kioctx *ctx)
 359{
 360	struct task_struct *tsk = current;
 361	DECLARE_WAITQUEUE(wait, tsk);
 362
 363	spin_lock_irq(&ctx->ctx_lock);
 364	if (!ctx->reqs_active)
 365		goto out;
 366
 367	add_wait_queue(&ctx->wait, &wait);
 368	set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 369	while (ctx->reqs_active) {
 370		spin_unlock_irq(&ctx->ctx_lock);
 371		io_schedule();
 372		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 373		spin_lock_irq(&ctx->ctx_lock);
 374	}
 375	__set_task_state(tsk, TASK_RUNNING);
 376	remove_wait_queue(&ctx->wait, &wait);
 377
 378out:
 379	spin_unlock_irq(&ctx->ctx_lock);
 380}
 381
 382/* wait_on_sync_kiocb:
 383 *	Waits on the given sync kiocb to complete.
 384 */
 385ssize_t wait_on_sync_kiocb(struct kiocb *iocb)
 386{
 387	while (iocb->ki_users) {
 388		set_current_state(TASK_UNINTERRUPTIBLE);
 389		if (!iocb->ki_users)
 390			break;
 391		io_schedule();
 392	}
 393	__set_current_state(TASK_RUNNING);
 394	return iocb->ki_user_data;
 395}
 396EXPORT_SYMBOL(wait_on_sync_kiocb);
 397
 398/* exit_aio: called when the last user of mm goes away.  At this point, 
 399 * there is no way for any new requests to be submited or any of the 
 400 * io_* syscalls to be called on the context.  However, there may be 
 401 * outstanding requests which hold references to the context; as they 
 402 * go away, they will call put_ioctx and release any pinned memory
 403 * associated with the request (held via struct page * references).
 
 404 */
 405void exit_aio(struct mm_struct *mm)
 406{
 407	struct kioctx *ctx;
 
 
 
 
 
 408
 409	while (!hlist_empty(&mm->ioctx_list)) {
 410		ctx = hlist_entry(mm->ioctx_list.first, struct kioctx, list);
 411		hlist_del_rcu(&ctx->list);
 412
 413		aio_cancel_all(ctx);
 
 
 
 
 
 
 
 
 414
 415		wait_for_all_aios(ctx);
 416		/*
 417		 * Ensure we don't leave the ctx on the aio_wq
 
 
 
 
 418		 */
 419		cancel_work_sync(&ctx->wq.work);
 420
 421		if (1 != atomic_read(&ctx->users))
 422			printk(KERN_DEBUG
 423				"exit_aio:ioctx still alive: %d %d %d\n",
 424				atomic_read(&ctx->users), ctx->dead,
 425				ctx->reqs_active);
 426		put_ioctx(ctx);
 427	}
 428}
 429
 430/* aio_get_req
 431 *	Allocate a slot for an aio request.  Increments the users count
 432 * of the kioctx so that the kioctx stays around until all requests are
 433 * complete.  Returns NULL if no requests are free.
 434 *
 435 * Returns with kiocb->users set to 2.  The io submit code path holds
 436 * an extra reference while submitting the i/o.
 437 * This prevents races between the aio code path referencing the
 438 * req (after submitting it) and aio_complete() freeing the req.
 439 */
 440static struct kiocb *__aio_get_req(struct kioctx *ctx)
 441{
 442	struct kiocb *req = NULL;
 443	struct aio_ring *ring;
 444	int okay = 0;
 445
 446	req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
 447	if (unlikely(!req))
 448		return NULL;
 449
 450	req->ki_flags = 0;
 451	req->ki_users = 2;
 452	req->ki_key = 0;
 453	req->ki_ctx = ctx;
 454	req->ki_cancel = NULL;
 455	req->ki_retry = NULL;
 456	req->ki_dtor = NULL;
 457	req->private = NULL;
 458	req->ki_iovec = NULL;
 459	INIT_LIST_HEAD(&req->ki_run_list);
 460	req->ki_eventfd = NULL;
 461
 462	/* Check if the completion queue has enough free space to
 463	 * accept an event from this io.
 464	 */
 465	spin_lock_irq(&ctx->ctx_lock);
 466	ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0);
 467	if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) {
 468		list_add(&req->ki_list, &ctx->active_reqs);
 469		ctx->reqs_active++;
 470		okay = 1;
 471	}
 472	kunmap_atomic(ring, KM_USER0);
 473	spin_unlock_irq(&ctx->ctx_lock);
 474
 475	if (!okay) {
 476		kmem_cache_free(kiocb_cachep, req);
 477		req = NULL;
 478	}
 479
 480	return req;
 
 481}
 482
 483static inline struct kiocb *aio_get_req(struct kioctx *ctx)
 484{
 485	struct kiocb *req;
 486	/* Handle a potential starvation case -- should be exceedingly rare as 
 487	 * requests will be stuck on fput_head only if the aio_fput_routine is 
 488	 * delayed and the requests were the last user of the struct file.
 489	 */
 490	req = __aio_get_req(ctx);
 491	if (unlikely(NULL == req)) {
 492		aio_fput_routine(NULL);
 493		req = __aio_get_req(ctx);
 494	}
 495	return req;
 496}
 497
 498static inline void really_put_req(struct kioctx *ctx, struct kiocb *req)
 499{
 500	assert_spin_locked(&ctx->ctx_lock);
 501
 502	if (req->ki_eventfd != NULL)
 503		eventfd_ctx_put(req->ki_eventfd);
 504	if (req->ki_dtor)
 505		req->ki_dtor(req);
 506	if (req->ki_iovec != &req->ki_inline_vec)
 507		kfree(req->ki_iovec);
 508	kmem_cache_free(kiocb_cachep, req);
 509	ctx->reqs_active--;
 510
 511	if (unlikely(!ctx->reqs_active && ctx->dead))
 512		wake_up_all(&ctx->wait);
 513}
 514
 515static void aio_fput_routine(struct work_struct *data)
 516{
 517	spin_lock_irq(&fput_lock);
 518	while (likely(!list_empty(&fput_head))) {
 519		struct kiocb *req = list_kiocb(fput_head.next);
 520		struct kioctx *ctx = req->ki_ctx;
 521
 522		list_del(&req->ki_list);
 523		spin_unlock_irq(&fput_lock);
 524
 525		/* Complete the fput(s) */
 526		if (req->ki_filp != NULL)
 527			fput(req->ki_filp);
 
 528
 529		/* Link the iocb into the context's free list */
 530		spin_lock_irq(&ctx->ctx_lock);
 531		really_put_req(ctx, req);
 532		spin_unlock_irq(&ctx->ctx_lock);
 
 533
 534		put_ioctx(ctx);
 535		spin_lock_irq(&fput_lock);
 536	}
 537	spin_unlock_irq(&fput_lock);
 538}
 539
 540/* __aio_put_req
 541 *	Returns true if this put was the last user of the request.
 542 */
 543static int __aio_put_req(struct kioctx *ctx, struct kiocb *req)
 544{
 545	dprintk(KERN_DEBUG "aio_put(%p): f_count=%ld\n",
 546		req, atomic_long_read(&req->ki_filp->f_count));
 547
 548	assert_spin_locked(&ctx->ctx_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 549
 550	req->ki_users--;
 551	BUG_ON(req->ki_users < 0);
 552	if (likely(req->ki_users))
 553		return 0;
 554	list_del(&req->ki_list);		/* remove from active_reqs */
 555	req->ki_cancel = NULL;
 556	req->ki_retry = NULL;
 557
 558	/*
 559	 * Try to optimize the aio and eventfd file* puts, by avoiding to
 560	 * schedule work in case it is not final fput() time. In normal cases,
 561	 * we would not be holding the last reference to the file*, so
 562	 * this function will be executed w/out any aio kthread wakeup.
 563	 */
 564	if (unlikely(!fput_atomic(req->ki_filp))) {
 565		get_ioctx(ctx);
 566		spin_lock(&fput_lock);
 567		list_add(&req->ki_list, &fput_head);
 568		spin_unlock(&fput_lock);
 569		schedule_work(&fput_work);
 570	} else {
 571		req->ki_filp = NULL;
 572		really_put_req(ctx, req);
 573	}
 574	return 1;
 575}
 576
 577/* aio_put_req
 578 *	Returns true if this put was the last user of the kiocb,
 579 *	false if the request is still in use.
 580 */
 581int aio_put_req(struct kiocb *req)
 582{
 583	struct kioctx *ctx = req->ki_ctx;
 584	int ret;
 585	spin_lock_irq(&ctx->ctx_lock);
 586	ret = __aio_put_req(ctx, req);
 587	spin_unlock_irq(&ctx->ctx_lock);
 588	return ret;
 589}
 590EXPORT_SYMBOL(aio_put_req);
 591
 592static struct kioctx *lookup_ioctx(unsigned long ctx_id)
 593{
 594	struct mm_struct *mm = current->mm;
 595	struct kioctx *ctx, *ret = NULL;
 596	struct hlist_node *n;
 597
 598	rcu_read_lock();
 599
 600	hlist_for_each_entry_rcu(ctx, n, &mm->ioctx_list, list) {
 601		/*
 602		 * RCU protects us against accessing freed memory but
 603		 * we have to be careful not to get a reference when the
 604		 * reference count already dropped to 0 (ctx->dead test
 605		 * is unreliable because of races).
 
 
 
 
 
 606		 */
 607		if (ctx->user_id == ctx_id && !ctx->dead && try_get_ioctx(ctx)){
 608			ret = ctx;
 609			break;
 610		}
 611	}
 612
 613	rcu_read_unlock();
 614	return ret;
 615}
 616
 617/*
 618 * Queue up a kiocb to be retried. Assumes that the kiocb
 619 * has already been marked as kicked, and places it on
 620 * the retry run list for the corresponding ioctx, if it
 621 * isn't already queued. Returns 1 if it actually queued
 622 * the kiocb (to tell the caller to activate the work
 623 * queue to process it), or 0, if it found that it was
 624 * already queued.
 625 */
 626static inline int __queue_kicked_iocb(struct kiocb *iocb)
 627{
 628	struct kioctx *ctx = iocb->ki_ctx;
 629
 630	assert_spin_locked(&ctx->ctx_lock);
 631
 632	if (list_empty(&iocb->ki_run_list)) {
 633		list_add_tail(&iocb->ki_run_list,
 634			&ctx->run_list);
 635		return 1;
 636	}
 637	return 0;
 638}
 639
 640/* aio_run_iocb
 641 *	This is the core aio execution routine. It is
 642 *	invoked both for initial i/o submission and
 643 *	subsequent retries via the aio_kick_handler.
 644 *	Expects to be invoked with iocb->ki_ctx->lock
 645 *	already held. The lock is released and reacquired
 646 *	as needed during processing.
 647 *
 648 * Calls the iocb retry method (already setup for the
 649 * iocb on initial submission) for operation specific
 650 * handling, but takes care of most of common retry
 651 * execution details for a given iocb. The retry method
 652 * needs to be non-blocking as far as possible, to avoid
 653 * holding up other iocbs waiting to be serviced by the
 654 * retry kernel thread.
 655 *
 656 * The trickier parts in this code have to do with
 657 * ensuring that only one retry instance is in progress
 658 * for a given iocb at any time. Providing that guarantee
 659 * simplifies the coding of individual aio operations as
 660 * it avoids various potential races.
 661 */
 662static ssize_t aio_run_iocb(struct kiocb *iocb)
 663{
 664	struct kioctx	*ctx = iocb->ki_ctx;
 665	ssize_t (*retry)(struct kiocb *);
 666	ssize_t ret;
 667
 668	if (!(retry = iocb->ki_retry)) {
 669		printk("aio_run_iocb: iocb->ki_retry = NULL\n");
 670		return 0;
 
 
 
 
 671	}
 672
 673	/*
 674	 * We don't want the next retry iteration for this
 675	 * operation to start until this one has returned and
 676	 * updated the iocb state. However, wait_queue functions
 677	 * can trigger a kick_iocb from interrupt context in the
 678	 * meantime, indicating that data is available for the next
 679	 * iteration. We want to remember that and enable the
 680	 * next retry iteration _after_ we are through with
 681	 * this one.
 682	 *
 683	 * So, in order to be able to register a "kick", but
 684	 * prevent it from being queued now, we clear the kick
 685	 * flag, but make the kick code *think* that the iocb is
 686	 * still on the run list until we are actually done.
 687	 * When we are done with this iteration, we check if
 688	 * the iocb was kicked in the meantime and if so, queue
 689	 * it up afresh.
 690	 */
 691
 692	kiocbClearKicked(iocb);
 
 
 
 
 
 
 693
 694	/*
 695	 * This is so that aio_complete knows it doesn't need to
 696	 * pull the iocb off the run list (We can't just call
 697	 * INIT_LIST_HEAD because we don't want a kick_iocb to
 698	 * queue this on the run list yet)
 699	 */
 700	iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL;
 701	spin_unlock_irq(&ctx->ctx_lock);
 702
 703	/* Quit retrying if the i/o has been cancelled */
 704	if (kiocbIsCancelled(iocb)) {
 705		ret = -EINTR;
 706		aio_complete(iocb, ret, 0);
 707		/* must not access the iocb after this */
 708		goto out;
 709	}
 710
 711	/*
 712	 * Now we are all set to call the retry method in async
 713	 * context.
 714	 */
 715	ret = retry(iocb);
 716
 717	if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) {
 718		/*
 719		 * There's no easy way to restart the syscall since other AIO's
 720		 * may be already running. Just fail this IO with EINTR.
 721		 */
 722		if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR ||
 723			     ret == -ERESTARTNOHAND || ret == -ERESTART_RESTARTBLOCK))
 724			ret = -EINTR;
 725		aio_complete(iocb, ret, 0);
 726	}
 727out:
 728	spin_lock_irq(&ctx->ctx_lock);
 729
 730	if (-EIOCBRETRY == ret) {
 731		/*
 732		 * OK, now that we are done with this iteration
 733		 * and know that there is more left to go,
 734		 * this is where we let go so that a subsequent
 735		 * "kick" can start the next iteration
 736		 */
 737
 738		/* will make __queue_kicked_iocb succeed from here on */
 739		INIT_LIST_HEAD(&iocb->ki_run_list);
 740		/* we must queue the next iteration ourselves, if it
 741		 * has already been kicked */
 742		if (kiocbIsKicked(iocb)) {
 743			__queue_kicked_iocb(iocb);
 744
 745			/*
 746			 * __queue_kicked_iocb will always return 1 here, because
 747			 * iocb->ki_run_list is empty at this point so it should
 748			 * be safe to unconditionally queue the context into the
 749			 * work queue.
 750			 */
 751			aio_queue_work(ctx);
 752		}
 753	}
 754	return ret;
 755}
 756
 757/*
 758 * __aio_run_iocbs:
 759 * 	Process all pending retries queued on the ioctx
 760 * 	run list.
 761 * Assumes it is operating within the aio issuer's mm
 762 * context.
 763 */
 764static int __aio_run_iocbs(struct kioctx *ctx)
 765{
 766	struct kiocb *iocb;
 767	struct list_head run_list;
 768
 769	assert_spin_locked(&ctx->ctx_lock);
 770
 771	list_replace_init(&ctx->run_list, &run_list);
 772	while (!list_empty(&run_list)) {
 773		iocb = list_entry(run_list.next, struct kiocb,
 774			ki_run_list);
 775		list_del(&iocb->ki_run_list);
 776		/*
 777		 * Hold an extra reference while retrying i/o.
 778		 */
 779		iocb->ki_users++;       /* grab extra reference */
 780		aio_run_iocb(iocb);
 781		__aio_put_req(ctx, iocb);
 782 	}
 783	if (!list_empty(&ctx->run_list))
 784		return 1;
 785	return 0;
 786}
 787
 788static void aio_queue_work(struct kioctx * ctx)
 789{
 790	unsigned long timeout;
 791	/*
 792	 * if someone is waiting, get the work started right
 793	 * away, otherwise, use a longer delay
 794	 */
 795	smp_mb();
 796	if (waitqueue_active(&ctx->wait))
 797		timeout = 1;
 798	else
 799		timeout = HZ/10;
 800	queue_delayed_work(aio_wq, &ctx->wq, timeout);
 801}
 802
 803/*
 804 * aio_run_all_iocbs:
 805 *	Process all pending retries queued on the ioctx
 806 *	run list, and keep running them until the list
 807 *	stays empty.
 808 * Assumes it is operating within the aio issuer's mm context.
 809 */
 810static inline void aio_run_all_iocbs(struct kioctx *ctx)
 811{
 812	spin_lock_irq(&ctx->ctx_lock);
 813	while (__aio_run_iocbs(ctx))
 814		;
 815	spin_unlock_irq(&ctx->ctx_lock);
 816}
 817
 818/*
 819 * aio_kick_handler:
 820 * 	Work queue handler triggered to process pending
 821 * 	retries on an ioctx. Takes on the aio issuer's
 822 *	mm context before running the iocbs, so that
 823 *	copy_xxx_user operates on the issuer's address
 824 *      space.
 825 * Run on aiod's context.
 826 */
 827static void aio_kick_handler(struct work_struct *work)
 828{
 829	struct kioctx *ctx = container_of(work, struct kioctx, wq.work);
 830	mm_segment_t oldfs = get_fs();
 831	struct mm_struct *mm;
 832	int requeue;
 833
 834	set_fs(USER_DS);
 835	use_mm(ctx->mm);
 836	spin_lock_irq(&ctx->ctx_lock);
 837	requeue =__aio_run_iocbs(ctx);
 838	mm = ctx->mm;
 839	spin_unlock_irq(&ctx->ctx_lock);
 840 	unuse_mm(mm);
 841	set_fs(oldfs);
 842	/*
 843	 * we're in a worker thread already, don't use queue_delayed_work,
 844	 */
 845	if (requeue)
 846		queue_delayed_work(aio_wq, &ctx->wq, 0);
 847}
 848
 849
 850/*
 851 * Called by kick_iocb to queue the kiocb for retry
 852 * and if required activate the aio work queue to process
 853 * it
 854 */
 855static void try_queue_kicked_iocb(struct kiocb *iocb)
 856{
 857 	struct kioctx	*ctx = iocb->ki_ctx;
 858	unsigned long flags;
 859	int run = 0;
 860
 861	spin_lock_irqsave(&ctx->ctx_lock, flags);
 862	/* set this inside the lock so that we can't race with aio_run_iocb()
 863	 * testing it and putting the iocb on the run list under the lock */
 864	if (!kiocbTryKick(iocb))
 865		run = __queue_kicked_iocb(iocb);
 866	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
 867	if (run)
 868		aio_queue_work(ctx);
 869}
 870
 871/*
 872 * kick_iocb:
 873 *      Called typically from a wait queue callback context
 874 *      to trigger a retry of the iocb.
 875 *      The retry is usually executed by aio workqueue
 876 *      threads (See aio_kick_handler).
 877 */
 878void kick_iocb(struct kiocb *iocb)
 879{
 880	/* sync iocbs are easy: they can only ever be executing from a 
 881	 * single context. */
 882	if (is_sync_kiocb(iocb)) {
 883		kiocbSetKicked(iocb);
 884	        wake_up_process(iocb->ki_obj.tsk);
 885		return;
 886	}
 887
 888	try_queue_kicked_iocb(iocb);
 889}
 890EXPORT_SYMBOL(kick_iocb);
 891
 892/* aio_complete
 893 *	Called when the io request on the given iocb is complete.
 894 *	Returns true if this is the last user of the request.  The 
 895 *	only other user of the request can be the cancellation code.
 896 */
 897int aio_complete(struct kiocb *iocb, long res, long res2)
 898{
 899	struct kioctx	*ctx = iocb->ki_ctx;
 900	struct aio_ring_info	*info;
 901	struct aio_ring	*ring;
 902	struct io_event	*event;
 
 903	unsigned long	flags;
 904	unsigned long	tail;
 905	int		ret;
 906
 907	/*
 908	 * Special case handling for sync iocbs:
 909	 *  - events go directly into the iocb for fast handling
 910	 *  - the sync task with the iocb in its stack holds the single iocb
 911	 *    ref, no other paths have a way to get another ref
 912	 *  - the sync task helpfully left a reference to itself in the iocb
 913	 */
 914	if (is_sync_kiocb(iocb)) {
 915		BUG_ON(iocb->ki_users != 1);
 916		iocb->ki_user_data = res;
 917		iocb->ki_users = 0;
 918		wake_up_process(iocb->ki_obj.tsk);
 919		return 1;
 920	}
 921
 922	info = &ctx->ring_info;
 923
 924	/* add a completion event to the ring buffer.
 925	 * must be done holding ctx->ctx_lock to prevent
 926	 * other code from messing with the tail
 927	 * pointer since we might be called from irq
 928	 * context.
 929	 */
 930	spin_lock_irqsave(&ctx->ctx_lock, flags);
 931
 932	if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
 933		list_del_init(&iocb->ki_run_list);
 934
 935	/*
 936	 * cancelled requests don't get events, userland was given one
 937	 * when the event got cancelled.
 938	 */
 939	if (kiocbIsCancelled(iocb))
 940		goto put_rq;
 941
 942	ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
 
 943
 944	tail = info->tail;
 945	event = aio_ring_event(info, tail, KM_IRQ0);
 946	if (++tail >= info->nr)
 947		tail = 0;
 948
 949	event->obj = (u64)(unsigned long)iocb->ki_obj.user;
 950	event->data = iocb->ki_user_data;
 951	event->res = res;
 952	event->res2 = res2;
 953
 954	dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n",
 955		ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data,
 956		res, res2);
 957
 958	/* after flagging the request as done, we
 959	 * must never even look at it again
 960	 */
 961	smp_wmb();	/* make event visible before updating tail */
 962
 963	info->tail = tail;
 
 
 
 964	ring->tail = tail;
 
 965
 966	put_aio_ring_event(event, KM_IRQ0);
 967	kunmap_atomic(ring, KM_IRQ1);
 
 
 
 
 
 
 968
 969	pr_debug("added to ring %p at [%lu]\n", iocb, tail);
 970
 971	/*
 972	 * Check if the user asked us to deliver the result through an
 973	 * eventfd. The eventfd_signal() function is safe to be called
 974	 * from IRQ context.
 975	 */
 976	if (iocb->ki_eventfd != NULL)
 977		eventfd_signal(iocb->ki_eventfd, 1);
 978
 979put_rq:
 980	/* everything turned out well, dispose of the aiocb. */
 981	ret = __aio_put_req(ctx, iocb);
 982
 983	/*
 984	 * We have to order our ring_info tail store above and test
 985	 * of the wait list below outside the wait lock.  This is
 986	 * like in wake_up_bit() where clearing a bit has to be
 987	 * ordered with the unlocked test.
 988	 */
 989	smp_mb();
 990
 991	if (waitqueue_active(&ctx->wait))
 992		wake_up(&ctx->wait);
 
 
 
 
 
 
 
 
 
 
 
 993
 994	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
 995	return ret;
 
 
 
 
 996}
 997EXPORT_SYMBOL(aio_complete);
 998
 999/* aio_read_evt
1000 *	Pull an event off of the ioctx's event ring.  Returns the number of 
1001 *	events fetched (0 or 1 ;-)
1002 *	FIXME: make this use cmpxchg.
1003 *	TODO: make the ringbuffer user mmap()able (requires FIXME).
1004 */
1005static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent)
 
1006{
1007	struct aio_ring_info *info = &ioctx->ring_info;
1008	struct aio_ring *ring;
1009	unsigned long head;
1010	int ret = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1011
1012	ring = kmap_atomic(info->ring_pages[0], KM_USER0);
1013	dprintk("in aio_read_evt h%lu t%lu m%lu\n",
1014		 (unsigned long)ring->head, (unsigned long)ring->tail,
1015		 (unsigned long)ring->nr);
1016
1017	if (ring->head == ring->tail)
1018		goto out;
1019
1020	spin_lock(&info->ring_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1021
1022	head = ring->head % info->nr;
1023	if (head != ring->tail) {
1024		struct io_event *evp = aio_ring_event(info, head, KM_USER1);
1025		*ent = *evp;
1026		head = (head + 1) % info->nr;
1027		smp_mb(); /* finish reading the event before updatng the head */
1028		ring->head = head;
1029		ret = 1;
1030		put_aio_ring_event(evp, KM_USER1);
1031	}
1032	spin_unlock(&info->ring_lock);
1033
 
 
 
 
 
1034out:
1035	kunmap_atomic(ring, KM_USER0);
1036	dprintk("leaving aio_read_evt: %d  h%lu t%lu\n", ret,
1037		 (unsigned long)ring->head, (unsigned long)ring->tail);
1038	return ret;
1039}
1040
1041struct aio_timeout {
1042	struct timer_list	timer;
1043	int			timed_out;
1044	struct task_struct	*p;
1045};
1046
1047static void timeout_func(unsigned long data)
1048{
1049	struct aio_timeout *to = (struct aio_timeout *)data;
1050
1051	to->timed_out = 1;
1052	wake_up_process(to->p);
1053}
1054
1055static inline void init_timeout(struct aio_timeout *to)
1056{
1057	setup_timer_on_stack(&to->timer, timeout_func, (unsigned long) to);
1058	to->timed_out = 0;
1059	to->p = current;
1060}
1061
1062static inline void set_timeout(long start_jiffies, struct aio_timeout *to,
1063			       const struct timespec *ts)
1064{
1065	to->timer.expires = start_jiffies + timespec_to_jiffies(ts);
1066	if (time_after(to->timer.expires, jiffies))
1067		add_timer(&to->timer);
1068	else
1069		to->timed_out = 1;
1070}
1071
1072static inline void clear_timeout(struct aio_timeout *to)
1073{
1074	del_singleshot_timer_sync(&to->timer);
1075}
1076
1077static int read_events(struct kioctx *ctx,
1078			long min_nr, long nr,
1079			struct io_event __user *event,
1080			struct timespec __user *timeout)
1081{
1082	long			start_jiffies = jiffies;
1083	struct task_struct	*tsk = current;
1084	DECLARE_WAITQUEUE(wait, tsk);
1085	int			ret;
1086	int			i = 0;
1087	struct io_event		ent;
1088	struct aio_timeout	to;
1089	int			retry = 0;
1090
1091	/* needed to zero any padding within an entry (there shouldn't be 
1092	 * any, but C is fun!
1093	 */
1094	memset(&ent, 0, sizeof(ent));
1095retry:
1096	ret = 0;
1097	while (likely(i < nr)) {
1098		ret = aio_read_evt(ctx, &ent);
1099		if (unlikely(ret <= 0))
1100			break;
1101
1102		dprintk("read event: %Lx %Lx %Lx %Lx\n",
1103			ent.data, ent.obj, ent.res, ent.res2);
1104
1105		/* Could we split the check in two? */
1106		ret = -EFAULT;
1107		if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1108			dprintk("aio: lost an event due to EFAULT.\n");
1109			break;
1110		}
1111		ret = 0;
1112
1113		/* Good, event copied to userland, update counts. */
1114		event ++;
1115		i ++;
1116	}
1117
1118	if (min_nr <= i)
1119		return i;
1120	if (ret)
 
 
 
 
 
 
 
 
 
 
 
 
 
1121		return ret;
1122
1123	/* End fast path */
1124
1125	/* racey check, but it gets redone */
1126	if (!retry && unlikely(!list_empty(&ctx->run_list))) {
1127		retry = 1;
1128		aio_run_all_iocbs(ctx);
1129		goto retry;
1130	}
1131
1132	init_timeout(&to);
1133	if (timeout) {
1134		struct timespec	ts;
1135		ret = -EFAULT;
1136		if (unlikely(copy_from_user(&ts, timeout, sizeof(ts))))
1137			goto out;
1138
1139		set_timeout(start_jiffies, &to, &ts);
1140	}
1141
1142	while (likely(i < nr)) {
1143		add_wait_queue_exclusive(&ctx->wait, &wait);
1144		do {
1145			set_task_state(tsk, TASK_INTERRUPTIBLE);
1146			ret = aio_read_evt(ctx, &ent);
1147			if (ret)
1148				break;
1149			if (min_nr <= i)
1150				break;
1151			if (unlikely(ctx->dead)) {
1152				ret = -EINVAL;
1153				break;
1154			}
1155			if (to.timed_out)	/* Only check after read evt */
1156				break;
1157			/* Try to only show up in io wait if there are ops
1158			 *  in flight */
1159			if (ctx->reqs_active)
1160				io_schedule();
1161			else
1162				schedule();
1163			if (signal_pending(tsk)) {
1164				ret = -EINTR;
1165				break;
1166			}
1167			/*ret = aio_read_evt(ctx, &ent);*/
1168		} while (1) ;
1169
1170		set_task_state(tsk, TASK_RUNNING);
1171		remove_wait_queue(&ctx->wait, &wait);
 
1172
1173		if (unlikely(ret <= 0))
1174			break;
1175
1176		ret = -EFAULT;
1177		if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) {
1178			dprintk("aio: lost an event due to EFAULT.\n");
1179			break;
1180		}
1181
1182		/* Good, event copied to userland, update counts. */
1183		event ++;
1184		i ++;
1185	}
1186
1187	if (timeout)
1188		clear_timeout(&to);
1189out:
1190	destroy_timer_on_stack(&to.timer);
1191	return i ? i : ret;
1192}
1193
1194/* Take an ioctx and remove it from the list of ioctx's.  Protects 
1195 * against races with itself via ->dead.
1196 */
1197static void io_destroy(struct kioctx *ioctx)
1198{
1199	struct mm_struct *mm = current->mm;
1200	int was_dead;
1201
1202	/* delete the entry from the list is someone else hasn't already */
1203	spin_lock(&mm->ioctx_lock);
1204	was_dead = ioctx->dead;
1205	ioctx->dead = 1;
1206	hlist_del_rcu(&ioctx->list);
1207	spin_unlock(&mm->ioctx_lock);
1208
1209	dprintk("aio_release(%p)\n", ioctx);
1210	if (likely(!was_dead))
1211		put_ioctx(ioctx);	/* twice for the list */
1212
1213	aio_cancel_all(ioctx);
1214	wait_for_all_aios(ioctx);
1215
1216	/*
1217	 * Wake up any waiters.  The setting of ctx->dead must be seen
1218	 * by other CPUs at this point.  Right now, we rely on the
1219	 * locking done by the above calls to ensure this consistency.
1220	 */
1221	wake_up_all(&ioctx->wait);
1222	put_ioctx(ioctx);	/* once for the lookup */
1223}
1224
1225/* sys_io_setup:
1226 *	Create an aio_context capable of receiving at least nr_events.
1227 *	ctxp must not point to an aio_context that already exists, and
1228 *	must be initialized to 0 prior to the call.  On successful
1229 *	creation of the aio_context, *ctxp is filled in with the resulting 
1230 *	handle.  May fail with -EINVAL if *ctxp is not initialized,
1231 *	if the specified nr_events exceeds internal limits.  May fail 
1232 *	with -EAGAIN if the specified nr_events exceeds the user's limit 
1233 *	of available events.  May fail with -ENOMEM if insufficient kernel
1234 *	resources are available.  May fail with -EFAULT if an invalid
1235 *	pointer is passed for ctxp.  Will fail with -ENOSYS if not
1236 *	implemented.
1237 */
1238SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1239{
1240	struct kioctx *ioctx = NULL;
1241	unsigned long ctx;
1242	long ret;
1243
1244	ret = get_user(ctx, ctxp);
1245	if (unlikely(ret))
1246		goto out;
1247
1248	ret = -EINVAL;
1249	if (unlikely(ctx || nr_events == 0)) {
1250		pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n",
1251		         ctx, nr_events);
1252		goto out;
1253	}
1254
1255	ioctx = ioctx_alloc(nr_events);
1256	ret = PTR_ERR(ioctx);
1257	if (!IS_ERR(ioctx)) {
1258		ret = put_user(ioctx->user_id, ctxp);
1259		if (!ret)
1260			return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1261
1262		get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */
1263		io_destroy(ioctx);
 
 
 
 
 
 
1264	}
1265
1266out:
1267	return ret;
1268}
 
1269
1270/* sys_io_destroy:
1271 *	Destroy the aio_context specified.  May cancel any outstanding 
1272 *	AIOs and block on completion.  Will fail with -ENOSYS if not
1273 *	implemented.  May fail with -EINVAL if the context pointed to
1274 *	is invalid.
1275 */
1276SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1277{
1278	struct kioctx *ioctx = lookup_ioctx(ctx);
1279	if (likely(NULL != ioctx)) {
1280		io_destroy(ioctx);
1281		return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1282	}
1283	pr_debug("EINVAL: io_destroy: invalid context id\n");
1284	return -EINVAL;
1285}
1286
1287static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret)
 
 
 
 
 
 
 
 
 
 
1288{
1289	struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg];
 
 
 
1290
1291	BUG_ON(ret <= 0);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1292
1293	while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) {
1294		ssize_t this = min((ssize_t)iov->iov_len, ret);
1295		iov->iov_base += this;
1296		iov->iov_len -= this;
1297		iocb->ki_left -= this;
1298		ret -= this;
1299		if (iov->iov_len == 0) {
1300			iocb->ki_cur_seg++;
1301			iov++;
 
 
 
 
 
 
 
1302		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1303	}
1304
1305	/* the caller should not have done more io than what fit in
1306	 * the remaining iovecs */
1307	BUG_ON(ret > 0 && iocb->ki_left == 0);
1308}
1309
1310static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
1311{
1312	struct file *file = iocb->ki_filp;
1313	struct address_space *mapping = file->f_mapping;
1314	struct inode *inode = mapping->host;
1315	ssize_t (*rw_op)(struct kiocb *, const struct iovec *,
1316			 unsigned long, loff_t);
1317	ssize_t ret = 0;
1318	unsigned short opcode;
1319
1320	if ((iocb->ki_opcode == IOCB_CMD_PREADV) ||
1321		(iocb->ki_opcode == IOCB_CMD_PREAD)) {
1322		rw_op = file->f_op->aio_read;
1323		opcode = IOCB_CMD_PREADV;
1324	} else {
1325		rw_op = file->f_op->aio_write;
1326		opcode = IOCB_CMD_PWRITEV;
1327	}
 
1328
1329	/* This matches the pread()/pwrite() logic */
1330	if (iocb->ki_pos < 0)
1331		return -EINVAL;
 
 
 
 
1332
1333	do {
1334		ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg],
1335			    iocb->ki_nr_segs - iocb->ki_cur_seg,
1336			    iocb->ki_pos);
1337		if (ret > 0)
1338			aio_advance_iovec(iocb, ret);
1339
1340	/* retry all partial writes.  retry partial reads as long as its a
1341	 * regular file. */
1342	} while (ret > 0 && iocb->ki_left > 0 &&
1343		 (opcode == IOCB_CMD_PWRITEV ||
1344		  (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode))));
1345
1346	/* This means we must have transferred all that we could */
1347	/* No need to retry anymore */
1348	if ((ret == 0) || (iocb->ki_left == 0))
1349		ret = iocb->ki_nbytes - iocb->ki_left;
1350
1351	/* If we managed to write some out we return that, rather than
1352	 * the eventual error. */
1353	if (opcode == IOCB_CMD_PWRITEV
1354	    && ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY
1355	    && iocb->ki_nbytes - iocb->ki_left)
1356		ret = iocb->ki_nbytes - iocb->ki_left;
1357
 
 
 
 
 
 
 
1358	return ret;
1359}
1360
1361static ssize_t aio_fdsync(struct kiocb *iocb)
 
1362{
1363	struct file *file = iocb->ki_filp;
1364	ssize_t ret = -EINVAL;
 
 
1365
1366	if (file->f_op->aio_fsync)
1367		ret = file->f_op->aio_fsync(iocb, 1);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1368	return ret;
1369}
1370
1371static ssize_t aio_fsync(struct kiocb *iocb)
1372{
1373	struct file *file = iocb->ki_filp;
1374	ssize_t ret = -EINVAL;
1375
1376	if (file->f_op->aio_fsync)
1377		ret = file->f_op->aio_fsync(iocb, 0);
1378	return ret;
 
1379}
1380
1381static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
 
1382{
1383	ssize_t ret;
1384
1385#ifdef CONFIG_COMPAT
1386	if (compat)
1387		ret = compat_rw_copy_check_uvector(type,
1388				(struct compat_iovec __user *)kiocb->ki_buf,
1389				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
1390				&kiocb->ki_iovec);
1391	else
1392#endif
1393		ret = rw_copy_check_uvector(type,
1394				(struct iovec __user *)kiocb->ki_buf,
1395				kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
1396				&kiocb->ki_iovec);
1397	if (ret < 0)
1398		goto out;
1399
1400	kiocb->ki_nr_segs = kiocb->ki_nbytes;
1401	kiocb->ki_cur_seg = 0;
1402	/* ki_nbytes/left now reflect bytes instead of segs */
1403	kiocb->ki_nbytes = ret;
1404	kiocb->ki_left = ret;
1405
1406	ret = 0;
1407out:
1408	return ret;
 
 
 
 
 
1409}
1410
1411static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
1412{
1413	kiocb->ki_iovec = &kiocb->ki_inline_vec;
1414	kiocb->ki_iovec->iov_base = kiocb->ki_buf;
1415	kiocb->ki_iovec->iov_len = kiocb->ki_left;
1416	kiocb->ki_nr_segs = 1;
1417	kiocb->ki_cur_seg = 0;
1418	return 0;
1419}
1420
1421/*
1422 * aio_setup_iocb:
1423 *	Performs the initial checks and aio retry method
1424 *	setup for the kiocb at the time of io submission.
 
 
 
1425 */
1426static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
1427{
1428	struct file *file = kiocb->ki_filp;
1429	ssize_t ret = 0;
1430
1431	switch (kiocb->ki_opcode) {
1432	case IOCB_CMD_PREAD:
1433		ret = -EBADF;
1434		if (unlikely(!(file->f_mode & FMODE_READ)))
1435			break;
1436		ret = -EFAULT;
1437		if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf,
1438			kiocb->ki_left)))
1439			break;
1440		ret = security_file_permission(file, MAY_READ);
1441		if (unlikely(ret))
1442			break;
1443		ret = aio_setup_single_vector(kiocb);
1444		if (ret)
1445			break;
1446		ret = -EINVAL;
1447		if (file->f_op->aio_read)
1448			kiocb->ki_retry = aio_rw_vect_retry;
1449		break;
1450	case IOCB_CMD_PWRITE:
1451		ret = -EBADF;
1452		if (unlikely(!(file->f_mode & FMODE_WRITE)))
1453			break;
1454		ret = -EFAULT;
1455		if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf,
1456			kiocb->ki_left)))
1457			break;
1458		ret = security_file_permission(file, MAY_WRITE);
1459		if (unlikely(ret))
1460			break;
1461		ret = aio_setup_single_vector(kiocb);
1462		if (ret)
1463			break;
1464		ret = -EINVAL;
1465		if (file->f_op->aio_write)
1466			kiocb->ki_retry = aio_rw_vect_retry;
1467		break;
1468	case IOCB_CMD_PREADV:
1469		ret = -EBADF;
1470		if (unlikely(!(file->f_mode & FMODE_READ)))
1471			break;
1472		ret = security_file_permission(file, MAY_READ);
1473		if (unlikely(ret))
1474			break;
1475		ret = aio_setup_vectored_rw(READ, kiocb, compat);
1476		if (ret)
1477			break;
1478		ret = -EINVAL;
1479		if (file->f_op->aio_read)
1480			kiocb->ki_retry = aio_rw_vect_retry;
1481		break;
1482	case IOCB_CMD_PWRITEV:
1483		ret = -EBADF;
1484		if (unlikely(!(file->f_mode & FMODE_WRITE)))
1485			break;
1486		ret = security_file_permission(file, MAY_WRITE);
1487		if (unlikely(ret))
1488			break;
1489		ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
1490		if (ret)
1491			break;
1492		ret = -EINVAL;
1493		if (file->f_op->aio_write)
1494			kiocb->ki_retry = aio_rw_vect_retry;
1495		break;
1496	case IOCB_CMD_FDSYNC:
1497		ret = -EINVAL;
1498		if (file->f_op->aio_fsync)
1499			kiocb->ki_retry = aio_fdsync;
1500		break;
1501	case IOCB_CMD_FSYNC:
1502		ret = -EINVAL;
1503		if (file->f_op->aio_fsync)
1504			kiocb->ki_retry = aio_fsync;
1505		break;
1506	default:
1507		dprintk("EINVAL: io_submit: no operation provided\n");
1508		ret = -EINVAL;
1509	}
 
 
 
1510
1511	if (!kiocb->ki_retry)
1512		return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1513
1514	return 0;
1515}
1516
1517static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1518			 struct iocb *iocb, bool compat)
1519{
1520	struct kiocb *req;
1521	struct file *file;
1522	ssize_t ret;
 
1523
1524	/* enforce forwards compatibility on users */
1525	if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
1526		pr_debug("EINVAL: io_submit: reserve field set\n");
1527		return -EINVAL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1528	}
 
 
1529
1530	/* prevent overflows */
1531	if (unlikely(
1532	    (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
1533	    (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
1534	    ((ssize_t)iocb->aio_nbytes < 0)
1535	   )) {
1536		pr_debug("EINVAL: io_submit: overflow check\n");
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1537		return -EINVAL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1538	}
 
 
 
 
 
 
 
 
 
1539
1540	file = fget(iocb->aio_fildes);
1541	if (unlikely(!file))
 
 
 
 
1542		return -EBADF;
1543
1544	req = aio_get_req(ctx);		/* returns with 2 references to req */
1545	if (unlikely(!req)) {
1546		fput(file);
1547		return -EAGAIN;
1548	}
1549	req->ki_filp = file;
1550	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
 
1551		/*
1552		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1553		 * instance of the file* now. The file descriptor must be
1554		 * an eventfd() fd, and will be signaled for each completed
1555		 * event using the eventfd_signal() function.
1556		 */
1557		req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
1558		if (IS_ERR(req->ki_eventfd)) {
1559			ret = PTR_ERR(req->ki_eventfd);
1560			req->ki_eventfd = NULL;
1561			goto out_put_req;
1562		}
1563	}
1564
1565	ret = put_user(req->ki_key, &user_iocb->aio_key);
1566	if (unlikely(ret)) {
1567		dprintk("EFAULT: aio_key\n");
1568		goto out_put_req;
1569	}
1570
1571	req->ki_obj.user = user_iocb;
1572	req->ki_user_data = iocb->aio_data;
1573	req->ki_pos = iocb->aio_offset;
 
1574
1575	req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
1576	req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
1577	req->ki_opcode = iocb->aio_lio_opcode;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1578
1579	ret = aio_setup_iocb(req, compat);
 
 
 
 
 
1580
1581	if (ret)
1582		goto out_put_req;
1583
1584	spin_lock_irq(&ctx->ctx_lock);
1585	/*
1586	 * We could have raced with io_destroy() and are currently holding a
1587	 * reference to ctx which should be destroyed. We cannot submit IO
1588	 * since ctx gets freed as soon as io_submit() puts its reference.  The
1589	 * check here is reliable: io_destroy() sets ctx->dead before waiting
1590	 * for outstanding IO and the barrier between these two is realized by
1591	 * unlock of mm->ioctx_lock and lock of ctx->ctx_lock.  Analogously we
1592	 * increment ctx->reqs_active before checking for ctx->dead and the
1593	 * barrier is realized by unlock and lock of ctx->ctx_lock. Thus if we
1594	 * don't see ctx->dead set here, io_destroy() waits for our IO to
1595	 * finish.
1596	 */
1597	if (ctx->dead) {
1598		spin_unlock_irq(&ctx->ctx_lock);
1599		ret = -EINVAL;
1600		goto out_put_req;
1601	}
1602	aio_run_iocb(req);
1603	if (!list_empty(&ctx->run_list)) {
1604		/* drain the run list */
1605		while (__aio_run_iocbs(ctx))
1606			;
 
 
 
 
1607	}
1608	spin_unlock_irq(&ctx->ctx_lock);
1609
1610	aio_put_req(req);	/* drop extra ref to req */
1611	return 0;
 
1612
1613out_put_req:
1614	aio_put_req(req);	/* drop extra ref to req */
1615	aio_put_req(req);	/* drop i/o ref to req */
1616	return ret;
 
 
 
 
 
 
 
 
 
 
 
1617}
1618
1619long do_io_submit(aio_context_t ctx_id, long nr,
1620		  struct iocb __user *__user *iocbpp, bool compat)
 
 
 
 
 
 
 
 
 
 
 
 
1621{
1622	struct kioctx *ctx;
1623	long ret = 0;
1624	int i;
1625	struct blk_plug plug;
1626
1627	if (unlikely(nr < 0))
1628		return -EINVAL;
1629
1630	if (unlikely(nr > LONG_MAX/sizeof(*iocbpp)))
1631		nr = LONG_MAX/sizeof(*iocbpp);
1632
1633	if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
1634		return -EFAULT;
1635
1636	ctx = lookup_ioctx(ctx_id);
1637	if (unlikely(!ctx)) {
1638		pr_debug("EINVAL: io_submit: invalid context id\n");
1639		return -EINVAL;
1640	}
1641
1642	blk_start_plug(&plug);
 
1643
1644	/*
1645	 * AKPM: should this return a partial result if some of the IOs were
1646	 * successfully submitted?
1647	 */
1648	for (i=0; i<nr; i++) {
1649		struct iocb __user *user_iocb;
1650		struct iocb tmp;
1651
1652		if (unlikely(__get_user(user_iocb, iocbpp + i))) {
1653			ret = -EFAULT;
1654			break;
1655		}
1656
1657		if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
1658			ret = -EFAULT;
1659			break;
1660		}
1661
1662		ret = io_submit_one(ctx, user_iocb, &tmp, compat);
1663		if (ret)
1664			break;
1665	}
1666	blk_finish_plug(&plug);
 
1667
1668	put_ioctx(ctx);
1669	return i ? i : ret;
1670}
1671
1672/* sys_io_submit:
1673 *	Queue the nr iocbs pointed to by iocbpp for processing.  Returns
1674 *	the number of iocbs queued.  May return -EINVAL if the aio_context
1675 *	specified by ctx_id is invalid, if nr is < 0, if the iocb at
1676 *	*iocbpp[0] is not properly initialized, if the operation specified
1677 *	is invalid for the file descriptor in the iocb.  May fail with
1678 *	-EFAULT if any of the data structures point to invalid data.  May
1679 *	fail with -EBADF if the file descriptor specified in the first
1680 *	iocb is invalid.  May fail with -EAGAIN if insufficient resources
1681 *	are available to queue any iocbs.  Will return 0 if nr is 0.  Will
1682 *	fail with -ENOSYS if not implemented.
1683 */
1684SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
1685		struct iocb __user * __user *, iocbpp)
1686{
1687	return do_io_submit(ctx_id, nr, iocbpp, 0);
1688}
 
 
1689
1690/* lookup_kiocb
1691 *	Finds a given iocb for cancellation.
1692 */
1693static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb,
1694				  u32 key)
1695{
1696	struct list_head *pos;
1697
1698	assert_spin_locked(&ctx->ctx_lock);
 
 
 
 
1699
1700	/* TODO: use a hash or array, this sucks. */
1701	list_for_each(pos, &ctx->active_reqs) {
1702		struct kiocb *kiocb = list_kiocb(pos);
1703		if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key)
1704			return kiocb;
 
 
 
 
 
 
 
 
 
 
 
1705	}
1706	return NULL;
 
 
 
 
1707}
 
1708
1709/* sys_io_cancel:
1710 *	Attempts to cancel an iocb previously passed to io_submit.  If
1711 *	the operation is successfully cancelled, the resulting event is
1712 *	copied into the memory pointed to by result without being placed
1713 *	into the completion queue and 0 is returned.  May fail with
1714 *	-EFAULT if any of the data structures pointed to are invalid.
1715 *	May fail with -EINVAL if aio_context specified by ctx_id is
1716 *	invalid.  May fail with -EAGAIN if the iocb specified was not
1717 *	cancelled.  Will fail with -ENOSYS if not implemented.
1718 */
1719SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
1720		struct io_event __user *, result)
1721{
1722	int (*cancel)(struct kiocb *iocb, struct io_event *res);
1723	struct kioctx *ctx;
1724	struct kiocb *kiocb;
 
1725	u32 key;
1726	int ret;
1727
1728	ret = get_user(key, &iocb->aio_key);
1729	if (unlikely(ret))
1730		return -EFAULT;
 
 
1731
1732	ctx = lookup_ioctx(ctx_id);
1733	if (unlikely(!ctx))
1734		return -EINVAL;
1735
1736	spin_lock_irq(&ctx->ctx_lock);
1737	ret = -EAGAIN;
1738	kiocb = lookup_kiocb(ctx, iocb, key);
1739	if (kiocb && kiocb->ki_cancel) {
1740		cancel = kiocb->ki_cancel;
1741		kiocb->ki_users ++;
1742		kiocbSetCancelled(kiocb);
1743	} else
1744		cancel = NULL;
1745	spin_unlock_irq(&ctx->ctx_lock);
1746
1747	if (NULL != cancel) {
1748		struct io_event tmp;
1749		pr_debug("calling cancel\n");
1750		memset(&tmp, 0, sizeof(tmp));
1751		tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user;
1752		tmp.data = kiocb->ki_user_data;
1753		ret = cancel(kiocb, &tmp);
1754		if (!ret) {
1755			/* Cancellation succeeded -- copy the result
1756			 * into the user's buffer.
1757			 */
1758			if (copy_to_user(result, &tmp, sizeof(tmp)))
1759				ret = -EFAULT;
1760		}
1761	} else
1762		ret = -EINVAL;
1763
1764	put_ioctx(ctx);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1765
1766	return ret;
1767}
1768
1769/* io_getevents:
1770 *	Attempts to read at least min_nr events and up to nr events from
1771 *	the completion queue for the aio_context specified by ctx_id. If
1772 *	it succeeds, the number of read events is returned. May fail with
1773 *	-EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
1774 *	out of range, if timeout is out of range.  May fail with -EFAULT
1775 *	if any of the memory specified is invalid.  May return 0 or
1776 *	< min_nr if the timeout specified by timeout has elapsed
1777 *	before sufficient events are available, where timeout == NULL
1778 *	specifies an infinite timeout. Note that the timeout pointed to by
1779 *	timeout is relative and will be updated if not NULL and the
1780 *	operation blocks. Will fail with -ENOSYS if not implemented.
1781 */
 
 
1782SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
1783		long, min_nr,
1784		long, nr,
1785		struct io_event __user *, events,
1786		struct timespec __user *, timeout)
1787{
1788	struct kioctx *ioctx = lookup_ioctx(ctx_id);
1789	long ret = -EINVAL;
1790
1791	if (likely(ioctx)) {
1792		if (likely(min_nr <= nr && min_nr >= 0))
1793			ret = read_events(ioctx, min_nr, nr, events, timeout);
1794		put_ioctx(ioctx);
1795	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1796
1797	asmlinkage_protect(5, ret, ctx_id, min_nr, nr, events, timeout);
 
 
1798	return ret;
1799}
v6.8
   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