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 #define pr_fmt(fmt) "%s: " fmt, __func__ 12 13 #include <linux/kernel.h> 14 #include <linux/init.h> 15 #include <linux/errno.h> 16 #include <linux/time.h> 17 #include <linux/aio_abi.h> 18 #include <linux/export.h> 19 #include <linux/syscalls.h> 20 #include <linux/backing-dev.h> 21 #include <linux/uio.h> 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/percpu.h> 30 #include <linux/slab.h> 31 #include <linux/timer.h> 32 #include <linux/aio.h> 33 #include <linux/highmem.h> 34 #include <linux/workqueue.h> 35 #include <linux/security.h> 36 #include <linux/eventfd.h> 37 #include <linux/blkdev.h> 38 #include <linux/compat.h> 39 #include <linux/anon_inodes.h> 40 #include <linux/migrate.h> 41 #include <linux/ramfs.h> 42 #include <linux/percpu-refcount.h> 43 44 #include <asm/kmap_types.h> 45 #include <asm/uaccess.h> 46 47 #include "internal.h" 48 49 #define AIO_RING_MAGIC 0xa10a10a1 50 #define AIO_RING_COMPAT_FEATURES 1 51 #define AIO_RING_INCOMPAT_FEATURES 0 52 struct aio_ring { 53 unsigned id; /* kernel internal index number */ 54 unsigned nr; /* number of io_events */ 55 unsigned head; 56 unsigned tail; 57 58 unsigned magic; 59 unsigned compat_features; 60 unsigned incompat_features; 61 unsigned header_length; /* size of aio_ring */ 62 63 64 struct io_event io_events[0]; 65 }; /* 128 bytes + ring size */ 66 67 #define AIO_RING_PAGES 8 68 69 struct kioctx_table { 70 struct rcu_head rcu; 71 unsigned nr; 72 struct kioctx *table[]; 73 }; 74 75 struct kioctx_cpu { 76 unsigned reqs_available; 77 }; 78 79 struct kioctx { 80 struct percpu_ref users; 81 atomic_t dead; 82 83 unsigned long user_id; 84 85 struct __percpu kioctx_cpu *cpu; 86 87 /* 88 * For percpu reqs_available, number of slots we move to/from global 89 * counter at a time: 90 */ 91 unsigned req_batch; 92 /* 93 * This is what userspace passed to io_setup(), it's not used for 94 * anything but counting against the global max_reqs quota. 95 * 96 * The real limit is nr_events - 1, which will be larger (see 97 * aio_setup_ring()) 98 */ 99 unsigned max_reqs; 100 101 /* Size of ringbuffer, in units of struct io_event */ 102 unsigned nr_events; 103 104 unsigned long mmap_base; 105 unsigned long mmap_size; 106 107 struct page **ring_pages; 108 long nr_pages; 109 110 struct rcu_head rcu_head; 111 struct work_struct free_work; 112 113 struct { 114 /* 115 * This counts the number of available slots in the ringbuffer, 116 * so we avoid overflowing it: it's decremented (if positive) 117 * when allocating a kiocb and incremented when the resulting 118 * io_event is pulled off the ringbuffer. 119 * 120 * We batch accesses to it with a percpu version. 121 */ 122 atomic_t reqs_available; 123 } ____cacheline_aligned_in_smp; 124 125 struct { 126 spinlock_t ctx_lock; 127 struct list_head active_reqs; /* used for cancellation */ 128 } ____cacheline_aligned_in_smp; 129 130 struct { 131 struct mutex ring_lock; 132 wait_queue_head_t wait; 133 } ____cacheline_aligned_in_smp; 134 135 struct { 136 unsigned tail; 137 spinlock_t completion_lock; 138 } ____cacheline_aligned_in_smp; 139 140 struct page *internal_pages[AIO_RING_PAGES]; 141 struct file *aio_ring_file; 142 143 unsigned id; 144 }; 145 146 /*------ sysctl variables----*/ 147 static DEFINE_SPINLOCK(aio_nr_lock); 148 unsigned long aio_nr; /* current system wide number of aio requests */ 149 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ 150 /*----end sysctl variables---*/ 151 152 static struct kmem_cache *kiocb_cachep; 153 static struct kmem_cache *kioctx_cachep; 154 155 /* aio_setup 156 * Creates the slab caches used by the aio routines, panic on 157 * failure as this is done early during the boot sequence. 158 */ 159 static int __init aio_setup(void) 160 { 161 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); 162 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); 163 164 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page)); 165 166 return 0; 167 } 168 __initcall(aio_setup); 169 170 static void aio_free_ring(struct kioctx *ctx) 171 { 172 int i; 173 struct file *aio_ring_file = ctx->aio_ring_file; 174 175 for (i = 0; i < ctx->nr_pages; i++) { 176 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i, 177 page_count(ctx->ring_pages[i])); 178 put_page(ctx->ring_pages[i]); 179 } 180 181 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) 182 kfree(ctx->ring_pages); 183 184 if (aio_ring_file) { 185 truncate_setsize(aio_ring_file->f_inode, 0); 186 pr_debug("pid(%d) i_nlink=%u d_count=%d d_unhashed=%d i_count=%d\n", 187 current->pid, aio_ring_file->f_inode->i_nlink, 188 aio_ring_file->f_path.dentry->d_count, 189 d_unhashed(aio_ring_file->f_path.dentry), 190 atomic_read(&aio_ring_file->f_inode->i_count)); 191 fput(aio_ring_file); 192 ctx->aio_ring_file = NULL; 193 } 194 } 195 196 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma) 197 { 198 vma->vm_ops = &generic_file_vm_ops; 199 return 0; 200 } 201 202 static const struct file_operations aio_ring_fops = { 203 .mmap = aio_ring_mmap, 204 }; 205 206 static int aio_set_page_dirty(struct page *page) 207 { 208 return 0; 209 } 210 211 #if IS_ENABLED(CONFIG_MIGRATION) 212 static int aio_migratepage(struct address_space *mapping, struct page *new, 213 struct page *old, enum migrate_mode mode) 214 { 215 struct kioctx *ctx = mapping->private_data; 216 unsigned long flags; 217 unsigned idx = old->index; 218 int rc; 219 220 /* Writeback must be complete */ 221 BUG_ON(PageWriteback(old)); 222 put_page(old); 223 224 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode); 225 if (rc != MIGRATEPAGE_SUCCESS) { 226 get_page(old); 227 return rc; 228 } 229 230 get_page(new); 231 232 spin_lock_irqsave(&ctx->completion_lock, flags); 233 migrate_page_copy(new, old); 234 ctx->ring_pages[idx] = new; 235 spin_unlock_irqrestore(&ctx->completion_lock, flags); 236 237 return rc; 238 } 239 #endif 240 241 static const struct address_space_operations aio_ctx_aops = { 242 .set_page_dirty = aio_set_page_dirty, 243 #if IS_ENABLED(CONFIG_MIGRATION) 244 .migratepage = aio_migratepage, 245 #endif 246 }; 247 248 static int aio_setup_ring(struct kioctx *ctx) 249 { 250 struct aio_ring *ring; 251 unsigned nr_events = ctx->max_reqs; 252 struct mm_struct *mm = current->mm; 253 unsigned long size, populate; 254 int nr_pages; 255 int i; 256 struct file *file; 257 258 /* Compensate for the ring buffer's head/tail overlap entry */ 259 nr_events += 2; /* 1 is required, 2 for good luck */ 260 261 size = sizeof(struct aio_ring); 262 size += sizeof(struct io_event) * nr_events; 263 264 nr_pages = PFN_UP(size); 265 if (nr_pages < 0) 266 return -EINVAL; 267 268 file = anon_inode_getfile_private("[aio]", &aio_ring_fops, ctx, O_RDWR); 269 if (IS_ERR(file)) { 270 ctx->aio_ring_file = NULL; 271 return -EAGAIN; 272 } 273 274 file->f_inode->i_mapping->a_ops = &aio_ctx_aops; 275 file->f_inode->i_mapping->private_data = ctx; 276 file->f_inode->i_size = PAGE_SIZE * (loff_t)nr_pages; 277 278 for (i = 0; i < nr_pages; i++) { 279 struct page *page; 280 page = find_or_create_page(file->f_inode->i_mapping, 281 i, GFP_HIGHUSER | __GFP_ZERO); 282 if (!page) 283 break; 284 pr_debug("pid(%d) page[%d]->count=%d\n", 285 current->pid, i, page_count(page)); 286 SetPageUptodate(page); 287 SetPageDirty(page); 288 unlock_page(page); 289 } 290 ctx->aio_ring_file = file; 291 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) 292 / sizeof(struct io_event); 293 294 ctx->ring_pages = ctx->internal_pages; 295 if (nr_pages > AIO_RING_PAGES) { 296 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *), 297 GFP_KERNEL); 298 if (!ctx->ring_pages) 299 return -ENOMEM; 300 } 301 302 ctx->mmap_size = nr_pages * PAGE_SIZE; 303 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size); 304 305 down_write(&mm->mmap_sem); 306 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size, 307 PROT_READ | PROT_WRITE, 308 MAP_SHARED | MAP_POPULATE, 0, &populate); 309 if (IS_ERR((void *)ctx->mmap_base)) { 310 up_write(&mm->mmap_sem); 311 ctx->mmap_size = 0; 312 aio_free_ring(ctx); 313 return -EAGAIN; 314 } 315 up_write(&mm->mmap_sem); 316 317 mm_populate(ctx->mmap_base, populate); 318 319 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base); 320 ctx->nr_pages = get_user_pages(current, mm, ctx->mmap_base, nr_pages, 321 1, 0, ctx->ring_pages, NULL); 322 for (i = 0; i < ctx->nr_pages; i++) 323 put_page(ctx->ring_pages[i]); 324 325 if (unlikely(ctx->nr_pages != nr_pages)) { 326 aio_free_ring(ctx); 327 return -EAGAIN; 328 } 329 330 ctx->user_id = ctx->mmap_base; 331 ctx->nr_events = nr_events; /* trusted copy */ 332 333 ring = kmap_atomic(ctx->ring_pages[0]); 334 ring->nr = nr_events; /* user copy */ 335 ring->id = ~0U; 336 ring->head = ring->tail = 0; 337 ring->magic = AIO_RING_MAGIC; 338 ring->compat_features = AIO_RING_COMPAT_FEATURES; 339 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; 340 ring->header_length = sizeof(struct aio_ring); 341 kunmap_atomic(ring); 342 flush_dcache_page(ctx->ring_pages[0]); 343 344 return 0; 345 } 346 347 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) 348 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) 349 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) 350 351 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) 352 { 353 struct kioctx *ctx = req->ki_ctx; 354 unsigned long flags; 355 356 spin_lock_irqsave(&ctx->ctx_lock, flags); 357 358 if (!req->ki_list.next) 359 list_add(&req->ki_list, &ctx->active_reqs); 360 361 req->ki_cancel = cancel; 362 363 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 364 } 365 EXPORT_SYMBOL(kiocb_set_cancel_fn); 366 367 static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb) 368 { 369 kiocb_cancel_fn *old, *cancel; 370 371 /* 372 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it 373 * actually has a cancel function, hence the cmpxchg() 374 */ 375 376 cancel = ACCESS_ONCE(kiocb->ki_cancel); 377 do { 378 if (!cancel || cancel == KIOCB_CANCELLED) 379 return -EINVAL; 380 381 old = cancel; 382 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED); 383 } while (cancel != old); 384 385 return cancel(kiocb); 386 } 387 388 static void free_ioctx_rcu(struct rcu_head *head) 389 { 390 struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); 391 392 free_percpu(ctx->cpu); 393 kmem_cache_free(kioctx_cachep, ctx); 394 } 395 396 /* 397 * When this function runs, the kioctx has been removed from the "hash table" 398 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted - 399 * now it's safe to cancel any that need to be. 400 */ 401 static void free_ioctx(struct work_struct *work) 402 { 403 struct kioctx *ctx = container_of(work, struct kioctx, free_work); 404 struct aio_ring *ring; 405 struct kiocb *req; 406 unsigned cpu, avail; 407 DEFINE_WAIT(wait); 408 409 spin_lock_irq(&ctx->ctx_lock); 410 411 while (!list_empty(&ctx->active_reqs)) { 412 req = list_first_entry(&ctx->active_reqs, 413 struct kiocb, ki_list); 414 415 list_del_init(&req->ki_list); 416 kiocb_cancel(ctx, req); 417 } 418 419 spin_unlock_irq(&ctx->ctx_lock); 420 421 for_each_possible_cpu(cpu) { 422 struct kioctx_cpu *kcpu = per_cpu_ptr(ctx->cpu, cpu); 423 424 atomic_add(kcpu->reqs_available, &ctx->reqs_available); 425 kcpu->reqs_available = 0; 426 } 427 428 while (1) { 429 prepare_to_wait(&ctx->wait, &wait, TASK_UNINTERRUPTIBLE); 430 431 ring = kmap_atomic(ctx->ring_pages[0]); 432 avail = (ring->head <= ring->tail) 433 ? ring->tail - ring->head 434 : ctx->nr_events - ring->head + ring->tail; 435 436 atomic_add(avail, &ctx->reqs_available); 437 ring->head = ring->tail; 438 kunmap_atomic(ring); 439 440 if (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1) 441 break; 442 443 schedule(); 444 } 445 finish_wait(&ctx->wait, &wait); 446 447 WARN_ON(atomic_read(&ctx->reqs_available) > ctx->nr_events - 1); 448 449 aio_free_ring(ctx); 450 451 pr_debug("freeing %p\n", ctx); 452 453 /* 454 * Here the call_rcu() is between the wait_event() for reqs_active to 455 * hit 0, and freeing the ioctx. 456 * 457 * aio_complete() decrements reqs_active, but it has to touch the ioctx 458 * after to issue a wakeup so we use rcu. 459 */ 460 call_rcu(&ctx->rcu_head, free_ioctx_rcu); 461 } 462 463 static void free_ioctx_ref(struct percpu_ref *ref) 464 { 465 struct kioctx *ctx = container_of(ref, struct kioctx, users); 466 467 INIT_WORK(&ctx->free_work, free_ioctx); 468 schedule_work(&ctx->free_work); 469 } 470 471 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) 472 { 473 unsigned i, new_nr; 474 struct kioctx_table *table, *old; 475 struct aio_ring *ring; 476 477 spin_lock(&mm->ioctx_lock); 478 table = rcu_dereference(mm->ioctx_table); 479 480 while (1) { 481 if (table) 482 for (i = 0; i < table->nr; i++) 483 if (!table->table[i]) { 484 ctx->id = i; 485 table->table[i] = ctx; 486 spin_unlock(&mm->ioctx_lock); 487 488 ring = kmap_atomic(ctx->ring_pages[0]); 489 ring->id = ctx->id; 490 kunmap_atomic(ring); 491 return 0; 492 } 493 494 new_nr = (table ? table->nr : 1) * 4; 495 496 spin_unlock(&mm->ioctx_lock); 497 498 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) * 499 new_nr, GFP_KERNEL); 500 if (!table) 501 return -ENOMEM; 502 503 table->nr = new_nr; 504 505 spin_lock(&mm->ioctx_lock); 506 old = rcu_dereference(mm->ioctx_table); 507 508 if (!old) { 509 rcu_assign_pointer(mm->ioctx_table, table); 510 } else if (table->nr > old->nr) { 511 memcpy(table->table, old->table, 512 old->nr * sizeof(struct kioctx *)); 513 514 rcu_assign_pointer(mm->ioctx_table, table); 515 kfree_rcu(old, rcu); 516 } else { 517 kfree(table); 518 table = old; 519 } 520 } 521 } 522 523 /* ioctx_alloc 524 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. 525 */ 526 static struct kioctx *ioctx_alloc(unsigned nr_events) 527 { 528 struct mm_struct *mm = current->mm; 529 struct kioctx *ctx; 530 int err = -ENOMEM; 531 532 /* 533 * We keep track of the number of available ringbuffer slots, to prevent 534 * overflow (reqs_available), and we also use percpu counters for this. 535 * 536 * So since up to half the slots might be on other cpu's percpu counters 537 * and unavailable, double nr_events so userspace sees what they 538 * expected: additionally, we move req_batch slots to/from percpu 539 * counters at a time, so make sure that isn't 0: 540 */ 541 nr_events = max(nr_events, num_possible_cpus() * 4); 542 nr_events *= 2; 543 544 /* Prevent overflows */ 545 if ((nr_events > (0x10000000U / sizeof(struct io_event))) || 546 (nr_events > (0x10000000U / sizeof(struct kiocb)))) { 547 pr_debug("ENOMEM: nr_events too high\n"); 548 return ERR_PTR(-EINVAL); 549 } 550 551 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL)) 552 return ERR_PTR(-EAGAIN); 553 554 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); 555 if (!ctx) 556 return ERR_PTR(-ENOMEM); 557 558 ctx->max_reqs = nr_events; 559 560 if (percpu_ref_init(&ctx->users, free_ioctx_ref)) 561 goto out_freectx; 562 563 spin_lock_init(&ctx->ctx_lock); 564 spin_lock_init(&ctx->completion_lock); 565 mutex_init(&ctx->ring_lock); 566 init_waitqueue_head(&ctx->wait); 567 568 INIT_LIST_HEAD(&ctx->active_reqs); 569 570 ctx->cpu = alloc_percpu(struct kioctx_cpu); 571 if (!ctx->cpu) 572 goto out_freeref; 573 574 if (aio_setup_ring(ctx) < 0) 575 goto out_freepcpu; 576 577 atomic_set(&ctx->reqs_available, ctx->nr_events - 1); 578 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4); 579 BUG_ON(!ctx->req_batch); 580 581 err = ioctx_add_table(ctx, mm); 582 if (err) 583 goto out_cleanup_noerr; 584 585 /* limit the number of system wide aios */ 586 spin_lock(&aio_nr_lock); 587 if (aio_nr + nr_events > (aio_max_nr * 2UL) || 588 aio_nr + nr_events < aio_nr) { 589 spin_unlock(&aio_nr_lock); 590 goto out_cleanup; 591 } 592 aio_nr += ctx->max_reqs; 593 spin_unlock(&aio_nr_lock); 594 595 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */ 596 597 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", 598 ctx, ctx->user_id, mm, ctx->nr_events); 599 return ctx; 600 601 out_cleanup: 602 err = -EAGAIN; 603 out_cleanup_noerr: 604 aio_free_ring(ctx); 605 out_freepcpu: 606 free_percpu(ctx->cpu); 607 out_freeref: 608 free_percpu(ctx->users.pcpu_count); 609 out_freectx: 610 if (ctx->aio_ring_file) 611 fput(ctx->aio_ring_file); 612 kmem_cache_free(kioctx_cachep, ctx); 613 pr_debug("error allocating ioctx %d\n", err); 614 return ERR_PTR(err); 615 } 616 617 /* kill_ioctx 618 * Cancels all outstanding aio requests on an aio context. Used 619 * when the processes owning a context have all exited to encourage 620 * the rapid destruction of the kioctx. 621 */ 622 static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx) 623 { 624 if (!atomic_xchg(&ctx->dead, 1)) { 625 struct kioctx_table *table; 626 627 spin_lock(&mm->ioctx_lock); 628 table = rcu_dereference(mm->ioctx_table); 629 630 WARN_ON(ctx != table->table[ctx->id]); 631 table->table[ctx->id] = NULL; 632 spin_unlock(&mm->ioctx_lock); 633 634 /* percpu_ref_kill() will do the necessary call_rcu() */ 635 wake_up_all(&ctx->wait); 636 637 /* 638 * It'd be more correct to do this in free_ioctx(), after all 639 * the outstanding kiocbs have finished - but by then io_destroy 640 * has already returned, so io_setup() could potentially return 641 * -EAGAIN with no ioctxs actually in use (as far as userspace 642 * could tell). 643 */ 644 spin_lock(&aio_nr_lock); 645 BUG_ON(aio_nr - ctx->max_reqs > aio_nr); 646 aio_nr -= ctx->max_reqs; 647 spin_unlock(&aio_nr_lock); 648 649 if (ctx->mmap_size) 650 vm_munmap(ctx->mmap_base, ctx->mmap_size); 651 652 percpu_ref_kill(&ctx->users); 653 } 654 } 655 656 /* wait_on_sync_kiocb: 657 * Waits on the given sync kiocb to complete. 658 */ 659 ssize_t wait_on_sync_kiocb(struct kiocb *req) 660 { 661 while (!req->ki_ctx) { 662 set_current_state(TASK_UNINTERRUPTIBLE); 663 if (req->ki_ctx) 664 break; 665 io_schedule(); 666 } 667 __set_current_state(TASK_RUNNING); 668 return req->ki_user_data; 669 } 670 EXPORT_SYMBOL(wait_on_sync_kiocb); 671 672 /* 673 * exit_aio: called when the last user of mm goes away. At this point, there is 674 * no way for any new requests to be submited or any of the io_* syscalls to be 675 * called on the context. 676 * 677 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on 678 * them. 679 */ 680 void exit_aio(struct mm_struct *mm) 681 { 682 struct kioctx_table *table; 683 struct kioctx *ctx; 684 unsigned i = 0; 685 686 while (1) { 687 rcu_read_lock(); 688 table = rcu_dereference(mm->ioctx_table); 689 690 do { 691 if (!table || i >= table->nr) { 692 rcu_read_unlock(); 693 rcu_assign_pointer(mm->ioctx_table, NULL); 694 if (table) 695 kfree(table); 696 return; 697 } 698 699 ctx = table->table[i++]; 700 } while (!ctx); 701 702 rcu_read_unlock(); 703 704 /* 705 * We don't need to bother with munmap() here - 706 * exit_mmap(mm) is coming and it'll unmap everything. 707 * Since aio_free_ring() uses non-zero ->mmap_size 708 * as indicator that it needs to unmap the area, 709 * just set it to 0; aio_free_ring() is the only 710 * place that uses ->mmap_size, so it's safe. 711 */ 712 ctx->mmap_size = 0; 713 714 kill_ioctx(mm, ctx); 715 } 716 } 717 718 static void put_reqs_available(struct kioctx *ctx, unsigned nr) 719 { 720 struct kioctx_cpu *kcpu; 721 722 preempt_disable(); 723 kcpu = this_cpu_ptr(ctx->cpu); 724 725 kcpu->reqs_available += nr; 726 while (kcpu->reqs_available >= ctx->req_batch * 2) { 727 kcpu->reqs_available -= ctx->req_batch; 728 atomic_add(ctx->req_batch, &ctx->reqs_available); 729 } 730 731 preempt_enable(); 732 } 733 734 static bool get_reqs_available(struct kioctx *ctx) 735 { 736 struct kioctx_cpu *kcpu; 737 bool ret = false; 738 739 preempt_disable(); 740 kcpu = this_cpu_ptr(ctx->cpu); 741 742 if (!kcpu->reqs_available) { 743 int old, avail = atomic_read(&ctx->reqs_available); 744 745 do { 746 if (avail < ctx->req_batch) 747 goto out; 748 749 old = avail; 750 avail = atomic_cmpxchg(&ctx->reqs_available, 751 avail, avail - ctx->req_batch); 752 } while (avail != old); 753 754 kcpu->reqs_available += ctx->req_batch; 755 } 756 757 ret = true; 758 kcpu->reqs_available--; 759 out: 760 preempt_enable(); 761 return ret; 762 } 763 764 /* aio_get_req 765 * Allocate a slot for an aio request. 766 * Returns NULL if no requests are free. 767 */ 768 static inline struct kiocb *aio_get_req(struct kioctx *ctx) 769 { 770 struct kiocb *req; 771 772 if (!get_reqs_available(ctx)) 773 return NULL; 774 775 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO); 776 if (unlikely(!req)) 777 goto out_put; 778 779 req->ki_ctx = ctx; 780 return req; 781 out_put: 782 put_reqs_available(ctx, 1); 783 return NULL; 784 } 785 786 static void kiocb_free(struct kiocb *req) 787 { 788 if (req->ki_filp) 789 fput(req->ki_filp); 790 if (req->ki_eventfd != NULL) 791 eventfd_ctx_put(req->ki_eventfd); 792 kmem_cache_free(kiocb_cachep, req); 793 } 794 795 static struct kioctx *lookup_ioctx(unsigned long ctx_id) 796 { 797 struct aio_ring __user *ring = (void __user *)ctx_id; 798 struct mm_struct *mm = current->mm; 799 struct kioctx *ctx, *ret = NULL; 800 struct kioctx_table *table; 801 unsigned id; 802 803 if (get_user(id, &ring->id)) 804 return NULL; 805 806 rcu_read_lock(); 807 table = rcu_dereference(mm->ioctx_table); 808 809 if (!table || id >= table->nr) 810 goto out; 811 812 ctx = table->table[id]; 813 if (ctx->user_id == ctx_id) { 814 percpu_ref_get(&ctx->users); 815 ret = ctx; 816 } 817 out: 818 rcu_read_unlock(); 819 return ret; 820 } 821 822 /* aio_complete 823 * Called when the io request on the given iocb is complete. 824 */ 825 void aio_complete(struct kiocb *iocb, long res, long res2) 826 { 827 struct kioctx *ctx = iocb->ki_ctx; 828 struct aio_ring *ring; 829 struct io_event *ev_page, *event; 830 unsigned long flags; 831 unsigned tail, pos; 832 833 /* 834 * Special case handling for sync iocbs: 835 * - events go directly into the iocb for fast handling 836 * - the sync task with the iocb in its stack holds the single iocb 837 * ref, no other paths have a way to get another ref 838 * - the sync task helpfully left a reference to itself in the iocb 839 */ 840 if (is_sync_kiocb(iocb)) { 841 iocb->ki_user_data = res; 842 smp_wmb(); 843 iocb->ki_ctx = ERR_PTR(-EXDEV); 844 wake_up_process(iocb->ki_obj.tsk); 845 return; 846 } 847 848 /* 849 * Take rcu_read_lock() in case the kioctx is being destroyed, as we 850 * need to issue a wakeup after incrementing reqs_available. 851 */ 852 rcu_read_lock(); 853 854 if (iocb->ki_list.next) { 855 unsigned long flags; 856 857 spin_lock_irqsave(&ctx->ctx_lock, flags); 858 list_del(&iocb->ki_list); 859 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 860 } 861 862 /* 863 * Add a completion event to the ring buffer. Must be done holding 864 * ctx->completion_lock to prevent other code from messing with the tail 865 * pointer since we might be called from irq context. 866 */ 867 spin_lock_irqsave(&ctx->completion_lock, flags); 868 869 tail = ctx->tail; 870 pos = tail + AIO_EVENTS_OFFSET; 871 872 if (++tail >= ctx->nr_events) 873 tail = 0; 874 875 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); 876 event = ev_page + pos % AIO_EVENTS_PER_PAGE; 877 878 event->obj = (u64)(unsigned long)iocb->ki_obj.user; 879 event->data = iocb->ki_user_data; 880 event->res = res; 881 event->res2 = res2; 882 883 kunmap_atomic(ev_page); 884 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); 885 886 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n", 887 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, 888 res, res2); 889 890 /* after flagging the request as done, we 891 * must never even look at it again 892 */ 893 smp_wmb(); /* make event visible before updating tail */ 894 895 ctx->tail = tail; 896 897 ring = kmap_atomic(ctx->ring_pages[0]); 898 ring->tail = tail; 899 kunmap_atomic(ring); 900 flush_dcache_page(ctx->ring_pages[0]); 901 902 spin_unlock_irqrestore(&ctx->completion_lock, flags); 903 904 pr_debug("added to ring %p at [%u]\n", iocb, tail); 905 906 /* 907 * Check if the user asked us to deliver the result through an 908 * eventfd. The eventfd_signal() function is safe to be called 909 * from IRQ context. 910 */ 911 if (iocb->ki_eventfd != NULL) 912 eventfd_signal(iocb->ki_eventfd, 1); 913 914 /* everything turned out well, dispose of the aiocb. */ 915 kiocb_free(iocb); 916 917 /* 918 * We have to order our ring_info tail store above and test 919 * of the wait list below outside the wait lock. This is 920 * like in wake_up_bit() where clearing a bit has to be 921 * ordered with the unlocked test. 922 */ 923 smp_mb(); 924 925 if (waitqueue_active(&ctx->wait)) 926 wake_up(&ctx->wait); 927 928 rcu_read_unlock(); 929 } 930 EXPORT_SYMBOL(aio_complete); 931 932 /* aio_read_events 933 * Pull an event off of the ioctx's event ring. Returns the number of 934 * events fetched 935 */ 936 static long aio_read_events_ring(struct kioctx *ctx, 937 struct io_event __user *event, long nr) 938 { 939 struct aio_ring *ring; 940 unsigned head, tail, pos; 941 long ret = 0; 942 int copy_ret; 943 944 mutex_lock(&ctx->ring_lock); 945 946 ring = kmap_atomic(ctx->ring_pages[0]); 947 head = ring->head; 948 tail = ring->tail; 949 kunmap_atomic(ring); 950 951 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events); 952 953 if (head == tail) 954 goto out; 955 956 while (ret < nr) { 957 long avail; 958 struct io_event *ev; 959 struct page *page; 960 961 avail = (head <= tail ? tail : ctx->nr_events) - head; 962 if (head == tail) 963 break; 964 965 avail = min(avail, nr - ret); 966 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - 967 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE)); 968 969 pos = head + AIO_EVENTS_OFFSET; 970 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]; 971 pos %= AIO_EVENTS_PER_PAGE; 972 973 ev = kmap(page); 974 copy_ret = copy_to_user(event + ret, ev + pos, 975 sizeof(*ev) * avail); 976 kunmap(page); 977 978 if (unlikely(copy_ret)) { 979 ret = -EFAULT; 980 goto out; 981 } 982 983 ret += avail; 984 head += avail; 985 head %= ctx->nr_events; 986 } 987 988 ring = kmap_atomic(ctx->ring_pages[0]); 989 ring->head = head; 990 kunmap_atomic(ring); 991 flush_dcache_page(ctx->ring_pages[0]); 992 993 pr_debug("%li h%u t%u\n", ret, head, tail); 994 995 put_reqs_available(ctx, ret); 996 out: 997 mutex_unlock(&ctx->ring_lock); 998 999 return ret; 1000 } 1001 1002 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr, 1003 struct io_event __user *event, long *i) 1004 { 1005 long ret = aio_read_events_ring(ctx, event + *i, nr - *i); 1006 1007 if (ret > 0) 1008 *i += ret; 1009 1010 if (unlikely(atomic_read(&ctx->dead))) 1011 ret = -EINVAL; 1012 1013 if (!*i) 1014 *i = ret; 1015 1016 return ret < 0 || *i >= min_nr; 1017 } 1018 1019 static long read_events(struct kioctx *ctx, long min_nr, long nr, 1020 struct io_event __user *event, 1021 struct timespec __user *timeout) 1022 { 1023 ktime_t until = { .tv64 = KTIME_MAX }; 1024 long ret = 0; 1025 1026 if (timeout) { 1027 struct timespec ts; 1028 1029 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) 1030 return -EFAULT; 1031 1032 until = timespec_to_ktime(ts); 1033 } 1034 1035 /* 1036 * Note that aio_read_events() is being called as the conditional - i.e. 1037 * we're calling it after prepare_to_wait() has set task state to 1038 * TASK_INTERRUPTIBLE. 1039 * 1040 * But aio_read_events() can block, and if it blocks it's going to flip 1041 * the task state back to TASK_RUNNING. 1042 * 1043 * This should be ok, provided it doesn't flip the state back to 1044 * TASK_RUNNING and return 0 too much - that causes us to spin. That 1045 * will only happen if the mutex_lock() call blocks, and we then find 1046 * the ringbuffer empty. So in practice we should be ok, but it's 1047 * something to be aware of when touching this code. 1048 */ 1049 wait_event_interruptible_hrtimeout(ctx->wait, 1050 aio_read_events(ctx, min_nr, nr, event, &ret), until); 1051 1052 if (!ret && signal_pending(current)) 1053 ret = -EINTR; 1054 1055 return ret; 1056 } 1057 1058 /* sys_io_setup: 1059 * Create an aio_context capable of receiving at least nr_events. 1060 * ctxp must not point to an aio_context that already exists, and 1061 * must be initialized to 0 prior to the call. On successful 1062 * creation of the aio_context, *ctxp is filled in with the resulting 1063 * handle. May fail with -EINVAL if *ctxp is not initialized, 1064 * if the specified nr_events exceeds internal limits. May fail 1065 * with -EAGAIN if the specified nr_events exceeds the user's limit 1066 * of available events. May fail with -ENOMEM if insufficient kernel 1067 * resources are available. May fail with -EFAULT if an invalid 1068 * pointer is passed for ctxp. Will fail with -ENOSYS if not 1069 * implemented. 1070 */ 1071 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp) 1072 { 1073 struct kioctx *ioctx = NULL; 1074 unsigned long ctx; 1075 long ret; 1076 1077 ret = get_user(ctx, ctxp); 1078 if (unlikely(ret)) 1079 goto out; 1080 1081 ret = -EINVAL; 1082 if (unlikely(ctx || nr_events == 0)) { 1083 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n", 1084 ctx, nr_events); 1085 goto out; 1086 } 1087 1088 ioctx = ioctx_alloc(nr_events); 1089 ret = PTR_ERR(ioctx); 1090 if (!IS_ERR(ioctx)) { 1091 ret = put_user(ioctx->user_id, ctxp); 1092 if (ret) 1093 kill_ioctx(current->mm, ioctx); 1094 percpu_ref_put(&ioctx->users); 1095 } 1096 1097 out: 1098 return ret; 1099 } 1100 1101 /* sys_io_destroy: 1102 * Destroy the aio_context specified. May cancel any outstanding 1103 * AIOs and block on completion. Will fail with -ENOSYS if not 1104 * implemented. May fail with -EINVAL if the context pointed to 1105 * is invalid. 1106 */ 1107 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx) 1108 { 1109 struct kioctx *ioctx = lookup_ioctx(ctx); 1110 if (likely(NULL != ioctx)) { 1111 kill_ioctx(current->mm, ioctx); 1112 percpu_ref_put(&ioctx->users); 1113 return 0; 1114 } 1115 pr_debug("EINVAL: io_destroy: invalid context id\n"); 1116 return -EINVAL; 1117 } 1118 1119 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *, 1120 unsigned long, loff_t); 1121 1122 static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb, 1123 int rw, char __user *buf, 1124 unsigned long *nr_segs, 1125 struct iovec **iovec, 1126 bool compat) 1127 { 1128 ssize_t ret; 1129 1130 *nr_segs = kiocb->ki_nbytes; 1131 1132 #ifdef CONFIG_COMPAT 1133 if (compat) 1134 ret = compat_rw_copy_check_uvector(rw, 1135 (struct compat_iovec __user *)buf, 1136 *nr_segs, 1, *iovec, iovec); 1137 else 1138 #endif 1139 ret = rw_copy_check_uvector(rw, 1140 (struct iovec __user *)buf, 1141 *nr_segs, 1, *iovec, iovec); 1142 if (ret < 0) 1143 return ret; 1144 1145 /* ki_nbytes now reflect bytes instead of segs */ 1146 kiocb->ki_nbytes = ret; 1147 return 0; 1148 } 1149 1150 static ssize_t aio_setup_single_vector(struct kiocb *kiocb, 1151 int rw, char __user *buf, 1152 unsigned long *nr_segs, 1153 struct iovec *iovec) 1154 { 1155 if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes))) 1156 return -EFAULT; 1157 1158 iovec->iov_base = buf; 1159 iovec->iov_len = kiocb->ki_nbytes; 1160 *nr_segs = 1; 1161 return 0; 1162 } 1163 1164 /* 1165 * aio_setup_iocb: 1166 * Performs the initial checks and aio retry method 1167 * setup for the kiocb at the time of io submission. 1168 */ 1169 static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode, 1170 char __user *buf, bool compat) 1171 { 1172 struct file *file = req->ki_filp; 1173 ssize_t ret; 1174 unsigned long nr_segs; 1175 int rw; 1176 fmode_t mode; 1177 aio_rw_op *rw_op; 1178 struct iovec inline_vec, *iovec = &inline_vec; 1179 1180 switch (opcode) { 1181 case IOCB_CMD_PREAD: 1182 case IOCB_CMD_PREADV: 1183 mode = FMODE_READ; 1184 rw = READ; 1185 rw_op = file->f_op->aio_read; 1186 goto rw_common; 1187 1188 case IOCB_CMD_PWRITE: 1189 case IOCB_CMD_PWRITEV: 1190 mode = FMODE_WRITE; 1191 rw = WRITE; 1192 rw_op = file->f_op->aio_write; 1193 goto rw_common; 1194 rw_common: 1195 if (unlikely(!(file->f_mode & mode))) 1196 return -EBADF; 1197 1198 if (!rw_op) 1199 return -EINVAL; 1200 1201 ret = (opcode == IOCB_CMD_PREADV || 1202 opcode == IOCB_CMD_PWRITEV) 1203 ? aio_setup_vectored_rw(req, rw, buf, &nr_segs, 1204 &iovec, compat) 1205 : aio_setup_single_vector(req, rw, buf, &nr_segs, 1206 iovec); 1207 if (ret) 1208 return ret; 1209 1210 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes); 1211 if (ret < 0) { 1212 if (iovec != &inline_vec) 1213 kfree(iovec); 1214 return ret; 1215 } 1216 1217 req->ki_nbytes = ret; 1218 1219 /* XXX: move/kill - rw_verify_area()? */ 1220 /* This matches the pread()/pwrite() logic */ 1221 if (req->ki_pos < 0) { 1222 ret = -EINVAL; 1223 break; 1224 } 1225 1226 if (rw == WRITE) 1227 file_start_write(file); 1228 1229 ret = rw_op(req, iovec, nr_segs, req->ki_pos); 1230 1231 if (rw == WRITE) 1232 file_end_write(file); 1233 break; 1234 1235 case IOCB_CMD_FDSYNC: 1236 if (!file->f_op->aio_fsync) 1237 return -EINVAL; 1238 1239 ret = file->f_op->aio_fsync(req, 1); 1240 break; 1241 1242 case IOCB_CMD_FSYNC: 1243 if (!file->f_op->aio_fsync) 1244 return -EINVAL; 1245 1246 ret = file->f_op->aio_fsync(req, 0); 1247 break; 1248 1249 default: 1250 pr_debug("EINVAL: no operation provided\n"); 1251 return -EINVAL; 1252 } 1253 1254 if (iovec != &inline_vec) 1255 kfree(iovec); 1256 1257 if (ret != -EIOCBQUEUED) { 1258 /* 1259 * There's no easy way to restart the syscall since other AIO's 1260 * may be already running. Just fail this IO with EINTR. 1261 */ 1262 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR || 1263 ret == -ERESTARTNOHAND || 1264 ret == -ERESTART_RESTARTBLOCK)) 1265 ret = -EINTR; 1266 aio_complete(req, ret, 0); 1267 } 1268 1269 return 0; 1270 } 1271 1272 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1273 struct iocb *iocb, bool compat) 1274 { 1275 struct kiocb *req; 1276 ssize_t ret; 1277 1278 /* enforce forwards compatibility on users */ 1279 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) { 1280 pr_debug("EINVAL: reserve field set\n"); 1281 return -EINVAL; 1282 } 1283 1284 /* prevent overflows */ 1285 if (unlikely( 1286 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1287 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1288 ((ssize_t)iocb->aio_nbytes < 0) 1289 )) { 1290 pr_debug("EINVAL: io_submit: overflow check\n"); 1291 return -EINVAL; 1292 } 1293 1294 req = aio_get_req(ctx); 1295 if (unlikely(!req)) 1296 return -EAGAIN; 1297 1298 req->ki_filp = fget(iocb->aio_fildes); 1299 if (unlikely(!req->ki_filp)) { 1300 ret = -EBADF; 1301 goto out_put_req; 1302 } 1303 1304 if (iocb->aio_flags & IOCB_FLAG_RESFD) { 1305 /* 1306 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an 1307 * instance of the file* now. The file descriptor must be 1308 * an eventfd() fd, and will be signaled for each completed 1309 * event using the eventfd_signal() function. 1310 */ 1311 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd); 1312 if (IS_ERR(req->ki_eventfd)) { 1313 ret = PTR_ERR(req->ki_eventfd); 1314 req->ki_eventfd = NULL; 1315 goto out_put_req; 1316 } 1317 } 1318 1319 ret = put_user(KIOCB_KEY, &user_iocb->aio_key); 1320 if (unlikely(ret)) { 1321 pr_debug("EFAULT: aio_key\n"); 1322 goto out_put_req; 1323 } 1324 1325 req->ki_obj.user = user_iocb; 1326 req->ki_user_data = iocb->aio_data; 1327 req->ki_pos = iocb->aio_offset; 1328 req->ki_nbytes = iocb->aio_nbytes; 1329 1330 ret = aio_run_iocb(req, iocb->aio_lio_opcode, 1331 (char __user *)(unsigned long)iocb->aio_buf, 1332 compat); 1333 if (ret) 1334 goto out_put_req; 1335 1336 return 0; 1337 out_put_req: 1338 put_reqs_available(ctx, 1); 1339 kiocb_free(req); 1340 return ret; 1341 } 1342 1343 long do_io_submit(aio_context_t ctx_id, long nr, 1344 struct iocb __user *__user *iocbpp, bool compat) 1345 { 1346 struct kioctx *ctx; 1347 long ret = 0; 1348 int i = 0; 1349 struct blk_plug plug; 1350 1351 if (unlikely(nr < 0)) 1352 return -EINVAL; 1353 1354 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp))) 1355 nr = LONG_MAX/sizeof(*iocbpp); 1356 1357 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1358 return -EFAULT; 1359 1360 ctx = lookup_ioctx(ctx_id); 1361 if (unlikely(!ctx)) { 1362 pr_debug("EINVAL: invalid context id\n"); 1363 return -EINVAL; 1364 } 1365 1366 blk_start_plug(&plug); 1367 1368 /* 1369 * AKPM: should this return a partial result if some of the IOs were 1370 * successfully submitted? 1371 */ 1372 for (i=0; i<nr; i++) { 1373 struct iocb __user *user_iocb; 1374 struct iocb tmp; 1375 1376 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1377 ret = -EFAULT; 1378 break; 1379 } 1380 1381 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1382 ret = -EFAULT; 1383 break; 1384 } 1385 1386 ret = io_submit_one(ctx, user_iocb, &tmp, compat); 1387 if (ret) 1388 break; 1389 } 1390 blk_finish_plug(&plug); 1391 1392 percpu_ref_put(&ctx->users); 1393 return i ? i : ret; 1394 } 1395 1396 /* sys_io_submit: 1397 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1398 * the number of iocbs queued. May return -EINVAL if the aio_context 1399 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1400 * *iocbpp[0] is not properly initialized, if the operation specified 1401 * is invalid for the file descriptor in the iocb. May fail with 1402 * -EFAULT if any of the data structures point to invalid data. May 1403 * fail with -EBADF if the file descriptor specified in the first 1404 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1405 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1406 * fail with -ENOSYS if not implemented. 1407 */ 1408 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, 1409 struct iocb __user * __user *, iocbpp) 1410 { 1411 return do_io_submit(ctx_id, nr, iocbpp, 0); 1412 } 1413 1414 /* lookup_kiocb 1415 * Finds a given iocb for cancellation. 1416 */ 1417 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 1418 u32 key) 1419 { 1420 struct list_head *pos; 1421 1422 assert_spin_locked(&ctx->ctx_lock); 1423 1424 if (key != KIOCB_KEY) 1425 return NULL; 1426 1427 /* TODO: use a hash or array, this sucks. */ 1428 list_for_each(pos, &ctx->active_reqs) { 1429 struct kiocb *kiocb = list_kiocb(pos); 1430 if (kiocb->ki_obj.user == iocb) 1431 return kiocb; 1432 } 1433 return NULL; 1434 } 1435 1436 /* sys_io_cancel: 1437 * Attempts to cancel an iocb previously passed to io_submit. If 1438 * the operation is successfully cancelled, the resulting event is 1439 * copied into the memory pointed to by result without being placed 1440 * into the completion queue and 0 is returned. May fail with 1441 * -EFAULT if any of the data structures pointed to are invalid. 1442 * May fail with -EINVAL if aio_context specified by ctx_id is 1443 * invalid. May fail with -EAGAIN if the iocb specified was not 1444 * cancelled. Will fail with -ENOSYS if not implemented. 1445 */ 1446 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, 1447 struct io_event __user *, result) 1448 { 1449 struct kioctx *ctx; 1450 struct kiocb *kiocb; 1451 u32 key; 1452 int ret; 1453 1454 ret = get_user(key, &iocb->aio_key); 1455 if (unlikely(ret)) 1456 return -EFAULT; 1457 1458 ctx = lookup_ioctx(ctx_id); 1459 if (unlikely(!ctx)) 1460 return -EINVAL; 1461 1462 spin_lock_irq(&ctx->ctx_lock); 1463 1464 kiocb = lookup_kiocb(ctx, iocb, key); 1465 if (kiocb) 1466 ret = kiocb_cancel(ctx, kiocb); 1467 else 1468 ret = -EINVAL; 1469 1470 spin_unlock_irq(&ctx->ctx_lock); 1471 1472 if (!ret) { 1473 /* 1474 * The result argument is no longer used - the io_event is 1475 * always delivered via the ring buffer. -EINPROGRESS indicates 1476 * cancellation is progress: 1477 */ 1478 ret = -EINPROGRESS; 1479 } 1480 1481 percpu_ref_put(&ctx->users); 1482 1483 return ret; 1484 } 1485 1486 /* io_getevents: 1487 * Attempts to read at least min_nr events and up to nr events from 1488 * the completion queue for the aio_context specified by ctx_id. If 1489 * it succeeds, the number of read events is returned. May fail with 1490 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is 1491 * out of range, if timeout is out of range. May fail with -EFAULT 1492 * if any of the memory specified is invalid. May return 0 or 1493 * < min_nr if the timeout specified by timeout has elapsed 1494 * before sufficient events are available, where timeout == NULL 1495 * specifies an infinite timeout. Note that the timeout pointed to by 1496 * timeout is relative. Will fail with -ENOSYS if not implemented. 1497 */ 1498 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, 1499 long, min_nr, 1500 long, nr, 1501 struct io_event __user *, events, 1502 struct timespec __user *, timeout) 1503 { 1504 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1505 long ret = -EINVAL; 1506 1507 if (likely(ioctx)) { 1508 if (likely(min_nr <= nr && min_nr >= 0)) 1509 ret = read_events(ioctx, min_nr, nr, events, timeout); 1510 percpu_ref_put(&ioctx->users); 1511 } 1512 return ret; 1513 } 1514