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/migrate.h> 40 #include <linux/ramfs.h> 41 #include <linux/percpu-refcount.h> 42 #include <linux/mount.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; /* Written to by userland or under ring_lock 56 * mutex by aio_read_events_ring(). */ 57 unsigned tail; 58 59 unsigned magic; 60 unsigned compat_features; 61 unsigned incompat_features; 62 unsigned header_length; /* size of aio_ring */ 63 64 65 struct io_event io_events[0]; 66 }; /* 128 bytes + ring size */ 67 68 #define AIO_RING_PAGES 8 69 70 struct kioctx_table { 71 struct rcu_head rcu; 72 unsigned nr; 73 struct kioctx *table[]; 74 }; 75 76 struct kioctx_cpu { 77 unsigned reqs_available; 78 }; 79 80 struct kioctx { 81 struct percpu_ref users; 82 atomic_t dead; 83 84 struct percpu_ref reqs; 85 86 unsigned long user_id; 87 88 struct __percpu kioctx_cpu *cpu; 89 90 /* 91 * For percpu reqs_available, number of slots we move to/from global 92 * counter at a time: 93 */ 94 unsigned req_batch; 95 /* 96 * This is what userspace passed to io_setup(), it's not used for 97 * anything but counting against the global max_reqs quota. 98 * 99 * The real limit is nr_events - 1, which will be larger (see 100 * aio_setup_ring()) 101 */ 102 unsigned max_reqs; 103 104 /* Size of ringbuffer, in units of struct io_event */ 105 unsigned nr_events; 106 107 unsigned long mmap_base; 108 unsigned long mmap_size; 109 110 struct page **ring_pages; 111 long nr_pages; 112 113 struct work_struct free_work; 114 115 /* 116 * signals when all in-flight requests are done 117 */ 118 struct completion *requests_done; 119 120 struct { 121 /* 122 * This counts the number of available slots in the ringbuffer, 123 * so we avoid overflowing it: it's decremented (if positive) 124 * when allocating a kiocb and incremented when the resulting 125 * io_event is pulled off the ringbuffer. 126 * 127 * We batch accesses to it with a percpu version. 128 */ 129 atomic_t reqs_available; 130 } ____cacheline_aligned_in_smp; 131 132 struct { 133 spinlock_t ctx_lock; 134 struct list_head active_reqs; /* used for cancellation */ 135 } ____cacheline_aligned_in_smp; 136 137 struct { 138 struct mutex ring_lock; 139 wait_queue_head_t wait; 140 } ____cacheline_aligned_in_smp; 141 142 struct { 143 unsigned tail; 144 unsigned completed_events; 145 spinlock_t completion_lock; 146 } ____cacheline_aligned_in_smp; 147 148 struct page *internal_pages[AIO_RING_PAGES]; 149 struct file *aio_ring_file; 150 151 unsigned id; 152 }; 153 154 /*------ sysctl variables----*/ 155 static DEFINE_SPINLOCK(aio_nr_lock); 156 unsigned long aio_nr; /* current system wide number of aio requests */ 157 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ 158 /*----end sysctl variables---*/ 159 160 static struct kmem_cache *kiocb_cachep; 161 static struct kmem_cache *kioctx_cachep; 162 163 static struct vfsmount *aio_mnt; 164 165 static const struct file_operations aio_ring_fops; 166 static const struct address_space_operations aio_ctx_aops; 167 168 /* Backing dev info for aio fs. 169 * -no dirty page accounting or writeback happens 170 */ 171 static struct backing_dev_info aio_fs_backing_dev_info = { 172 .name = "aiofs", 173 .state = 0, 174 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_MAP_COPY, 175 }; 176 177 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages) 178 { 179 struct qstr this = QSTR_INIT("[aio]", 5); 180 struct file *file; 181 struct path path; 182 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb); 183 if (IS_ERR(inode)) 184 return ERR_CAST(inode); 185 186 inode->i_mapping->a_ops = &aio_ctx_aops; 187 inode->i_mapping->private_data = ctx; 188 inode->i_mapping->backing_dev_info = &aio_fs_backing_dev_info; 189 inode->i_size = PAGE_SIZE * nr_pages; 190 191 path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this); 192 if (!path.dentry) { 193 iput(inode); 194 return ERR_PTR(-ENOMEM); 195 } 196 path.mnt = mntget(aio_mnt); 197 198 d_instantiate(path.dentry, inode); 199 file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops); 200 if (IS_ERR(file)) { 201 path_put(&path); 202 return file; 203 } 204 205 file->f_flags = O_RDWR; 206 return file; 207 } 208 209 static struct dentry *aio_mount(struct file_system_type *fs_type, 210 int flags, const char *dev_name, void *data) 211 { 212 static const struct dentry_operations ops = { 213 .d_dname = simple_dname, 214 }; 215 return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC); 216 } 217 218 /* aio_setup 219 * Creates the slab caches used by the aio routines, panic on 220 * failure as this is done early during the boot sequence. 221 */ 222 static int __init aio_setup(void) 223 { 224 static struct file_system_type aio_fs = { 225 .name = "aio", 226 .mount = aio_mount, 227 .kill_sb = kill_anon_super, 228 }; 229 aio_mnt = kern_mount(&aio_fs); 230 if (IS_ERR(aio_mnt)) 231 panic("Failed to create aio fs mount."); 232 233 if (bdi_init(&aio_fs_backing_dev_info)) 234 panic("Failed to init aio fs backing dev info."); 235 236 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); 237 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); 238 239 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page)); 240 241 return 0; 242 } 243 __initcall(aio_setup); 244 245 static void put_aio_ring_file(struct kioctx *ctx) 246 { 247 struct file *aio_ring_file = ctx->aio_ring_file; 248 if (aio_ring_file) { 249 truncate_setsize(aio_ring_file->f_inode, 0); 250 251 /* Prevent further access to the kioctx from migratepages */ 252 spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock); 253 aio_ring_file->f_inode->i_mapping->private_data = NULL; 254 ctx->aio_ring_file = NULL; 255 spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock); 256 257 fput(aio_ring_file); 258 } 259 } 260 261 static void aio_free_ring(struct kioctx *ctx) 262 { 263 int i; 264 265 /* Disconnect the kiotx from the ring file. This prevents future 266 * accesses to the kioctx from page migration. 267 */ 268 put_aio_ring_file(ctx); 269 270 for (i = 0; i < ctx->nr_pages; i++) { 271 struct page *page; 272 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i, 273 page_count(ctx->ring_pages[i])); 274 page = ctx->ring_pages[i]; 275 if (!page) 276 continue; 277 ctx->ring_pages[i] = NULL; 278 put_page(page); 279 } 280 281 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) { 282 kfree(ctx->ring_pages); 283 ctx->ring_pages = NULL; 284 } 285 } 286 287 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma) 288 { 289 vma->vm_flags |= VM_DONTEXPAND; 290 vma->vm_ops = &generic_file_vm_ops; 291 return 0; 292 } 293 294 static void aio_ring_remap(struct file *file, struct vm_area_struct *vma) 295 { 296 struct mm_struct *mm = vma->vm_mm; 297 struct kioctx_table *table; 298 int i; 299 300 spin_lock(&mm->ioctx_lock); 301 rcu_read_lock(); 302 table = rcu_dereference(mm->ioctx_table); 303 for (i = 0; i < table->nr; i++) { 304 struct kioctx *ctx; 305 306 ctx = table->table[i]; 307 if (ctx && ctx->aio_ring_file == file) { 308 ctx->user_id = ctx->mmap_base = vma->vm_start; 309 break; 310 } 311 } 312 313 rcu_read_unlock(); 314 spin_unlock(&mm->ioctx_lock); 315 } 316 317 static const struct file_operations aio_ring_fops = { 318 .mmap = aio_ring_mmap, 319 .mremap = aio_ring_remap, 320 }; 321 322 #if IS_ENABLED(CONFIG_MIGRATION) 323 static int aio_migratepage(struct address_space *mapping, struct page *new, 324 struct page *old, enum migrate_mode mode) 325 { 326 struct kioctx *ctx; 327 unsigned long flags; 328 pgoff_t idx; 329 int rc; 330 331 rc = 0; 332 333 /* mapping->private_lock here protects against the kioctx teardown. */ 334 spin_lock(&mapping->private_lock); 335 ctx = mapping->private_data; 336 if (!ctx) { 337 rc = -EINVAL; 338 goto out; 339 } 340 341 /* The ring_lock mutex. The prevents aio_read_events() from writing 342 * to the ring's head, and prevents page migration from mucking in 343 * a partially initialized kiotx. 344 */ 345 if (!mutex_trylock(&ctx->ring_lock)) { 346 rc = -EAGAIN; 347 goto out; 348 } 349 350 idx = old->index; 351 if (idx < (pgoff_t)ctx->nr_pages) { 352 /* Make sure the old page hasn't already been changed */ 353 if (ctx->ring_pages[idx] != old) 354 rc = -EAGAIN; 355 } else 356 rc = -EINVAL; 357 358 if (rc != 0) 359 goto out_unlock; 360 361 /* Writeback must be complete */ 362 BUG_ON(PageWriteback(old)); 363 get_page(new); 364 365 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1); 366 if (rc != MIGRATEPAGE_SUCCESS) { 367 put_page(new); 368 goto out_unlock; 369 } 370 371 /* Take completion_lock to prevent other writes to the ring buffer 372 * while the old page is copied to the new. This prevents new 373 * events from being lost. 374 */ 375 spin_lock_irqsave(&ctx->completion_lock, flags); 376 migrate_page_copy(new, old); 377 BUG_ON(ctx->ring_pages[idx] != old); 378 ctx->ring_pages[idx] = new; 379 spin_unlock_irqrestore(&ctx->completion_lock, flags); 380 381 /* The old page is no longer accessible. */ 382 put_page(old); 383 384 out_unlock: 385 mutex_unlock(&ctx->ring_lock); 386 out: 387 spin_unlock(&mapping->private_lock); 388 return rc; 389 } 390 #endif 391 392 static const struct address_space_operations aio_ctx_aops = { 393 .set_page_dirty = __set_page_dirty_no_writeback, 394 #if IS_ENABLED(CONFIG_MIGRATION) 395 .migratepage = aio_migratepage, 396 #endif 397 }; 398 399 static int aio_setup_ring(struct kioctx *ctx) 400 { 401 struct aio_ring *ring; 402 unsigned nr_events = ctx->max_reqs; 403 struct mm_struct *mm = current->mm; 404 unsigned long size, unused; 405 int nr_pages; 406 int i; 407 struct file *file; 408 409 /* Compensate for the ring buffer's head/tail overlap entry */ 410 nr_events += 2; /* 1 is required, 2 for good luck */ 411 412 size = sizeof(struct aio_ring); 413 size += sizeof(struct io_event) * nr_events; 414 415 nr_pages = PFN_UP(size); 416 if (nr_pages < 0) 417 return -EINVAL; 418 419 file = aio_private_file(ctx, nr_pages); 420 if (IS_ERR(file)) { 421 ctx->aio_ring_file = NULL; 422 return -ENOMEM; 423 } 424 425 ctx->aio_ring_file = file; 426 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) 427 / sizeof(struct io_event); 428 429 ctx->ring_pages = ctx->internal_pages; 430 if (nr_pages > AIO_RING_PAGES) { 431 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *), 432 GFP_KERNEL); 433 if (!ctx->ring_pages) { 434 put_aio_ring_file(ctx); 435 return -ENOMEM; 436 } 437 } 438 439 for (i = 0; i < nr_pages; i++) { 440 struct page *page; 441 page = find_or_create_page(file->f_inode->i_mapping, 442 i, GFP_HIGHUSER | __GFP_ZERO); 443 if (!page) 444 break; 445 pr_debug("pid(%d) page[%d]->count=%d\n", 446 current->pid, i, page_count(page)); 447 SetPageUptodate(page); 448 unlock_page(page); 449 450 ctx->ring_pages[i] = page; 451 } 452 ctx->nr_pages = i; 453 454 if (unlikely(i != nr_pages)) { 455 aio_free_ring(ctx); 456 return -ENOMEM; 457 } 458 459 ctx->mmap_size = nr_pages * PAGE_SIZE; 460 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size); 461 462 down_write(&mm->mmap_sem); 463 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size, 464 PROT_READ | PROT_WRITE, 465 MAP_SHARED, 0, &unused); 466 up_write(&mm->mmap_sem); 467 if (IS_ERR((void *)ctx->mmap_base)) { 468 ctx->mmap_size = 0; 469 aio_free_ring(ctx); 470 return -ENOMEM; 471 } 472 473 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base); 474 475 ctx->user_id = ctx->mmap_base; 476 ctx->nr_events = nr_events; /* trusted copy */ 477 478 ring = kmap_atomic(ctx->ring_pages[0]); 479 ring->nr = nr_events; /* user copy */ 480 ring->id = ~0U; 481 ring->head = ring->tail = 0; 482 ring->magic = AIO_RING_MAGIC; 483 ring->compat_features = AIO_RING_COMPAT_FEATURES; 484 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; 485 ring->header_length = sizeof(struct aio_ring); 486 kunmap_atomic(ring); 487 flush_dcache_page(ctx->ring_pages[0]); 488 489 return 0; 490 } 491 492 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) 493 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) 494 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) 495 496 void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) 497 { 498 struct kioctx *ctx = req->ki_ctx; 499 unsigned long flags; 500 501 spin_lock_irqsave(&ctx->ctx_lock, flags); 502 503 if (!req->ki_list.next) 504 list_add(&req->ki_list, &ctx->active_reqs); 505 506 req->ki_cancel = cancel; 507 508 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 509 } 510 EXPORT_SYMBOL(kiocb_set_cancel_fn); 511 512 static int kiocb_cancel(struct kiocb *kiocb) 513 { 514 kiocb_cancel_fn *old, *cancel; 515 516 /* 517 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it 518 * actually has a cancel function, hence the cmpxchg() 519 */ 520 521 cancel = ACCESS_ONCE(kiocb->ki_cancel); 522 do { 523 if (!cancel || cancel == KIOCB_CANCELLED) 524 return -EINVAL; 525 526 old = cancel; 527 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED); 528 } while (cancel != old); 529 530 return cancel(kiocb); 531 } 532 533 static void free_ioctx(struct work_struct *work) 534 { 535 struct kioctx *ctx = container_of(work, struct kioctx, free_work); 536 537 pr_debug("freeing %p\n", ctx); 538 539 aio_free_ring(ctx); 540 free_percpu(ctx->cpu); 541 percpu_ref_exit(&ctx->reqs); 542 percpu_ref_exit(&ctx->users); 543 kmem_cache_free(kioctx_cachep, ctx); 544 } 545 546 static void free_ioctx_reqs(struct percpu_ref *ref) 547 { 548 struct kioctx *ctx = container_of(ref, struct kioctx, reqs); 549 550 /* At this point we know that there are no any in-flight requests */ 551 if (ctx->requests_done) 552 complete(ctx->requests_done); 553 554 INIT_WORK(&ctx->free_work, free_ioctx); 555 schedule_work(&ctx->free_work); 556 } 557 558 /* 559 * When this function runs, the kioctx has been removed from the "hash table" 560 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted - 561 * now it's safe to cancel any that need to be. 562 */ 563 static void free_ioctx_users(struct percpu_ref *ref) 564 { 565 struct kioctx *ctx = container_of(ref, struct kioctx, users); 566 struct kiocb *req; 567 568 spin_lock_irq(&ctx->ctx_lock); 569 570 while (!list_empty(&ctx->active_reqs)) { 571 req = list_first_entry(&ctx->active_reqs, 572 struct kiocb, ki_list); 573 574 list_del_init(&req->ki_list); 575 kiocb_cancel(req); 576 } 577 578 spin_unlock_irq(&ctx->ctx_lock); 579 580 percpu_ref_kill(&ctx->reqs); 581 percpu_ref_put(&ctx->reqs); 582 } 583 584 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) 585 { 586 unsigned i, new_nr; 587 struct kioctx_table *table, *old; 588 struct aio_ring *ring; 589 590 spin_lock(&mm->ioctx_lock); 591 table = rcu_dereference_raw(mm->ioctx_table); 592 593 while (1) { 594 if (table) 595 for (i = 0; i < table->nr; i++) 596 if (!table->table[i]) { 597 ctx->id = i; 598 table->table[i] = ctx; 599 spin_unlock(&mm->ioctx_lock); 600 601 /* While kioctx setup is in progress, 602 * we are protected from page migration 603 * changes ring_pages by ->ring_lock. 604 */ 605 ring = kmap_atomic(ctx->ring_pages[0]); 606 ring->id = ctx->id; 607 kunmap_atomic(ring); 608 return 0; 609 } 610 611 new_nr = (table ? table->nr : 1) * 4; 612 spin_unlock(&mm->ioctx_lock); 613 614 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) * 615 new_nr, GFP_KERNEL); 616 if (!table) 617 return -ENOMEM; 618 619 table->nr = new_nr; 620 621 spin_lock(&mm->ioctx_lock); 622 old = rcu_dereference_raw(mm->ioctx_table); 623 624 if (!old) { 625 rcu_assign_pointer(mm->ioctx_table, table); 626 } else if (table->nr > old->nr) { 627 memcpy(table->table, old->table, 628 old->nr * sizeof(struct kioctx *)); 629 630 rcu_assign_pointer(mm->ioctx_table, table); 631 kfree_rcu(old, rcu); 632 } else { 633 kfree(table); 634 table = old; 635 } 636 } 637 } 638 639 static void aio_nr_sub(unsigned nr) 640 { 641 spin_lock(&aio_nr_lock); 642 if (WARN_ON(aio_nr - nr > aio_nr)) 643 aio_nr = 0; 644 else 645 aio_nr -= nr; 646 spin_unlock(&aio_nr_lock); 647 } 648 649 /* ioctx_alloc 650 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. 651 */ 652 static struct kioctx *ioctx_alloc(unsigned nr_events) 653 { 654 struct mm_struct *mm = current->mm; 655 struct kioctx *ctx; 656 int err = -ENOMEM; 657 658 /* 659 * We keep track of the number of available ringbuffer slots, to prevent 660 * overflow (reqs_available), and we also use percpu counters for this. 661 * 662 * So since up to half the slots might be on other cpu's percpu counters 663 * and unavailable, double nr_events so userspace sees what they 664 * expected: additionally, we move req_batch slots to/from percpu 665 * counters at a time, so make sure that isn't 0: 666 */ 667 nr_events = max(nr_events, num_possible_cpus() * 4); 668 nr_events *= 2; 669 670 /* Prevent overflows */ 671 if ((nr_events > (0x10000000U / sizeof(struct io_event))) || 672 (nr_events > (0x10000000U / sizeof(struct kiocb)))) { 673 pr_debug("ENOMEM: nr_events too high\n"); 674 return ERR_PTR(-EINVAL); 675 } 676 677 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL)) 678 return ERR_PTR(-EAGAIN); 679 680 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); 681 if (!ctx) 682 return ERR_PTR(-ENOMEM); 683 684 ctx->max_reqs = nr_events; 685 686 spin_lock_init(&ctx->ctx_lock); 687 spin_lock_init(&ctx->completion_lock); 688 mutex_init(&ctx->ring_lock); 689 /* Protect against page migration throughout kiotx setup by keeping 690 * the ring_lock mutex held until setup is complete. */ 691 mutex_lock(&ctx->ring_lock); 692 init_waitqueue_head(&ctx->wait); 693 694 INIT_LIST_HEAD(&ctx->active_reqs); 695 696 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL)) 697 goto err; 698 699 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL)) 700 goto err; 701 702 ctx->cpu = alloc_percpu(struct kioctx_cpu); 703 if (!ctx->cpu) 704 goto err; 705 706 err = aio_setup_ring(ctx); 707 if (err < 0) 708 goto err; 709 710 atomic_set(&ctx->reqs_available, ctx->nr_events - 1); 711 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4); 712 if (ctx->req_batch < 1) 713 ctx->req_batch = 1; 714 715 /* limit the number of system wide aios */ 716 spin_lock(&aio_nr_lock); 717 if (aio_nr + nr_events > (aio_max_nr * 2UL) || 718 aio_nr + nr_events < aio_nr) { 719 spin_unlock(&aio_nr_lock); 720 err = -EAGAIN; 721 goto err_ctx; 722 } 723 aio_nr += ctx->max_reqs; 724 spin_unlock(&aio_nr_lock); 725 726 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */ 727 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */ 728 729 err = ioctx_add_table(ctx, mm); 730 if (err) 731 goto err_cleanup; 732 733 /* Release the ring_lock mutex now that all setup is complete. */ 734 mutex_unlock(&ctx->ring_lock); 735 736 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", 737 ctx, ctx->user_id, mm, ctx->nr_events); 738 return ctx; 739 740 err_cleanup: 741 aio_nr_sub(ctx->max_reqs); 742 err_ctx: 743 aio_free_ring(ctx); 744 err: 745 mutex_unlock(&ctx->ring_lock); 746 free_percpu(ctx->cpu); 747 percpu_ref_exit(&ctx->reqs); 748 percpu_ref_exit(&ctx->users); 749 kmem_cache_free(kioctx_cachep, ctx); 750 pr_debug("error allocating ioctx %d\n", err); 751 return ERR_PTR(err); 752 } 753 754 /* kill_ioctx 755 * Cancels all outstanding aio requests on an aio context. Used 756 * when the processes owning a context have all exited to encourage 757 * the rapid destruction of the kioctx. 758 */ 759 static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx, 760 struct completion *requests_done) 761 { 762 struct kioctx_table *table; 763 764 if (atomic_xchg(&ctx->dead, 1)) 765 return -EINVAL; 766 767 768 spin_lock(&mm->ioctx_lock); 769 table = rcu_dereference_raw(mm->ioctx_table); 770 WARN_ON(ctx != table->table[ctx->id]); 771 table->table[ctx->id] = NULL; 772 spin_unlock(&mm->ioctx_lock); 773 774 /* percpu_ref_kill() will do the necessary call_rcu() */ 775 wake_up_all(&ctx->wait); 776 777 /* 778 * It'd be more correct to do this in free_ioctx(), after all 779 * the outstanding kiocbs have finished - but by then io_destroy 780 * has already returned, so io_setup() could potentially return 781 * -EAGAIN with no ioctxs actually in use (as far as userspace 782 * could tell). 783 */ 784 aio_nr_sub(ctx->max_reqs); 785 786 if (ctx->mmap_size) 787 vm_munmap(ctx->mmap_base, ctx->mmap_size); 788 789 ctx->requests_done = requests_done; 790 percpu_ref_kill(&ctx->users); 791 return 0; 792 } 793 794 /* wait_on_sync_kiocb: 795 * Waits on the given sync kiocb to complete. 796 */ 797 ssize_t wait_on_sync_kiocb(struct kiocb *req) 798 { 799 while (!req->ki_ctx) { 800 set_current_state(TASK_UNINTERRUPTIBLE); 801 if (req->ki_ctx) 802 break; 803 io_schedule(); 804 } 805 __set_current_state(TASK_RUNNING); 806 return req->ki_user_data; 807 } 808 EXPORT_SYMBOL(wait_on_sync_kiocb); 809 810 /* 811 * exit_aio: called when the last user of mm goes away. At this point, there is 812 * no way for any new requests to be submited or any of the io_* syscalls to be 813 * called on the context. 814 * 815 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on 816 * them. 817 */ 818 void exit_aio(struct mm_struct *mm) 819 { 820 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table); 821 int i; 822 823 if (!table) 824 return; 825 826 for (i = 0; i < table->nr; ++i) { 827 struct kioctx *ctx = table->table[i]; 828 struct completion requests_done = 829 COMPLETION_INITIALIZER_ONSTACK(requests_done); 830 831 if (!ctx) 832 continue; 833 /* 834 * We don't need to bother with munmap() here - exit_mmap(mm) 835 * is coming and it'll unmap everything. And we simply can't, 836 * this is not necessarily our ->mm. 837 * Since kill_ioctx() uses non-zero ->mmap_size as indicator 838 * that it needs to unmap the area, just set it to 0. 839 */ 840 ctx->mmap_size = 0; 841 kill_ioctx(mm, ctx, &requests_done); 842 843 /* Wait until all IO for the context are done. */ 844 wait_for_completion(&requests_done); 845 } 846 847 RCU_INIT_POINTER(mm->ioctx_table, NULL); 848 kfree(table); 849 } 850 851 static void put_reqs_available(struct kioctx *ctx, unsigned nr) 852 { 853 struct kioctx_cpu *kcpu; 854 unsigned long flags; 855 856 local_irq_save(flags); 857 kcpu = this_cpu_ptr(ctx->cpu); 858 kcpu->reqs_available += nr; 859 860 while (kcpu->reqs_available >= ctx->req_batch * 2) { 861 kcpu->reqs_available -= ctx->req_batch; 862 atomic_add(ctx->req_batch, &ctx->reqs_available); 863 } 864 865 local_irq_restore(flags); 866 } 867 868 static bool get_reqs_available(struct kioctx *ctx) 869 { 870 struct kioctx_cpu *kcpu; 871 bool ret = false; 872 unsigned long flags; 873 874 local_irq_save(flags); 875 kcpu = this_cpu_ptr(ctx->cpu); 876 if (!kcpu->reqs_available) { 877 int old, avail = atomic_read(&ctx->reqs_available); 878 879 do { 880 if (avail < ctx->req_batch) 881 goto out; 882 883 old = avail; 884 avail = atomic_cmpxchg(&ctx->reqs_available, 885 avail, avail - ctx->req_batch); 886 } while (avail != old); 887 888 kcpu->reqs_available += ctx->req_batch; 889 } 890 891 ret = true; 892 kcpu->reqs_available--; 893 out: 894 local_irq_restore(flags); 895 return ret; 896 } 897 898 /* refill_reqs_available 899 * Updates the reqs_available reference counts used for tracking the 900 * number of free slots in the completion ring. This can be called 901 * from aio_complete() (to optimistically update reqs_available) or 902 * from aio_get_req() (the we're out of events case). It must be 903 * called holding ctx->completion_lock. 904 */ 905 static void refill_reqs_available(struct kioctx *ctx, unsigned head, 906 unsigned tail) 907 { 908 unsigned events_in_ring, completed; 909 910 /* Clamp head since userland can write to it. */ 911 head %= ctx->nr_events; 912 if (head <= tail) 913 events_in_ring = tail - head; 914 else 915 events_in_ring = ctx->nr_events - (head - tail); 916 917 completed = ctx->completed_events; 918 if (events_in_ring < completed) 919 completed -= events_in_ring; 920 else 921 completed = 0; 922 923 if (!completed) 924 return; 925 926 ctx->completed_events -= completed; 927 put_reqs_available(ctx, completed); 928 } 929 930 /* user_refill_reqs_available 931 * Called to refill reqs_available when aio_get_req() encounters an 932 * out of space in the completion ring. 933 */ 934 static void user_refill_reqs_available(struct kioctx *ctx) 935 { 936 spin_lock_irq(&ctx->completion_lock); 937 if (ctx->completed_events) { 938 struct aio_ring *ring; 939 unsigned head; 940 941 /* Access of ring->head may race with aio_read_events_ring() 942 * here, but that's okay since whether we read the old version 943 * or the new version, and either will be valid. The important 944 * part is that head cannot pass tail since we prevent 945 * aio_complete() from updating tail by holding 946 * ctx->completion_lock. Even if head is invalid, the check 947 * against ctx->completed_events below will make sure we do the 948 * safe/right thing. 949 */ 950 ring = kmap_atomic(ctx->ring_pages[0]); 951 head = ring->head; 952 kunmap_atomic(ring); 953 954 refill_reqs_available(ctx, head, ctx->tail); 955 } 956 957 spin_unlock_irq(&ctx->completion_lock); 958 } 959 960 /* aio_get_req 961 * Allocate a slot for an aio request. 962 * Returns NULL if no requests are free. 963 */ 964 static inline struct kiocb *aio_get_req(struct kioctx *ctx) 965 { 966 struct kiocb *req; 967 968 if (!get_reqs_available(ctx)) { 969 user_refill_reqs_available(ctx); 970 if (!get_reqs_available(ctx)) 971 return NULL; 972 } 973 974 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO); 975 if (unlikely(!req)) 976 goto out_put; 977 978 percpu_ref_get(&ctx->reqs); 979 980 req->ki_ctx = ctx; 981 return req; 982 out_put: 983 put_reqs_available(ctx, 1); 984 return NULL; 985 } 986 987 static void kiocb_free(struct kiocb *req) 988 { 989 if (req->ki_filp) 990 fput(req->ki_filp); 991 if (req->ki_eventfd != NULL) 992 eventfd_ctx_put(req->ki_eventfd); 993 kmem_cache_free(kiocb_cachep, req); 994 } 995 996 static struct kioctx *lookup_ioctx(unsigned long ctx_id) 997 { 998 struct aio_ring __user *ring = (void __user *)ctx_id; 999 struct mm_struct *mm = current->mm; 1000 struct kioctx *ctx, *ret = NULL; 1001 struct kioctx_table *table; 1002 unsigned id; 1003 1004 if (get_user(id, &ring->id)) 1005 return NULL; 1006 1007 rcu_read_lock(); 1008 table = rcu_dereference(mm->ioctx_table); 1009 1010 if (!table || id >= table->nr) 1011 goto out; 1012 1013 ctx = table->table[id]; 1014 if (ctx && ctx->user_id == ctx_id) { 1015 percpu_ref_get(&ctx->users); 1016 ret = ctx; 1017 } 1018 out: 1019 rcu_read_unlock(); 1020 return ret; 1021 } 1022 1023 /* aio_complete 1024 * Called when the io request on the given iocb is complete. 1025 */ 1026 void aio_complete(struct kiocb *iocb, long res, long res2) 1027 { 1028 struct kioctx *ctx = iocb->ki_ctx; 1029 struct aio_ring *ring; 1030 struct io_event *ev_page, *event; 1031 unsigned tail, pos, head; 1032 unsigned long flags; 1033 1034 /* 1035 * Special case handling for sync iocbs: 1036 * - events go directly into the iocb for fast handling 1037 * - the sync task with the iocb in its stack holds the single iocb 1038 * ref, no other paths have a way to get another ref 1039 * - the sync task helpfully left a reference to itself in the iocb 1040 */ 1041 if (is_sync_kiocb(iocb)) { 1042 iocb->ki_user_data = res; 1043 smp_wmb(); 1044 iocb->ki_ctx = ERR_PTR(-EXDEV); 1045 wake_up_process(iocb->ki_obj.tsk); 1046 return; 1047 } 1048 1049 if (iocb->ki_list.next) { 1050 unsigned long flags; 1051 1052 spin_lock_irqsave(&ctx->ctx_lock, flags); 1053 list_del(&iocb->ki_list); 1054 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 1055 } 1056 1057 /* 1058 * Add a completion event to the ring buffer. Must be done holding 1059 * ctx->completion_lock to prevent other code from messing with the tail 1060 * pointer since we might be called from irq context. 1061 */ 1062 spin_lock_irqsave(&ctx->completion_lock, flags); 1063 1064 tail = ctx->tail; 1065 pos = tail + AIO_EVENTS_OFFSET; 1066 1067 if (++tail >= ctx->nr_events) 1068 tail = 0; 1069 1070 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); 1071 event = ev_page + pos % AIO_EVENTS_PER_PAGE; 1072 1073 event->obj = (u64)(unsigned long)iocb->ki_obj.user; 1074 event->data = iocb->ki_user_data; 1075 event->res = res; 1076 event->res2 = res2; 1077 1078 kunmap_atomic(ev_page); 1079 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); 1080 1081 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n", 1082 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, 1083 res, res2); 1084 1085 /* after flagging the request as done, we 1086 * must never even look at it again 1087 */ 1088 smp_wmb(); /* make event visible before updating tail */ 1089 1090 ctx->tail = tail; 1091 1092 ring = kmap_atomic(ctx->ring_pages[0]); 1093 head = ring->head; 1094 ring->tail = tail; 1095 kunmap_atomic(ring); 1096 flush_dcache_page(ctx->ring_pages[0]); 1097 1098 ctx->completed_events++; 1099 if (ctx->completed_events > 1) 1100 refill_reqs_available(ctx, head, tail); 1101 spin_unlock_irqrestore(&ctx->completion_lock, flags); 1102 1103 pr_debug("added to ring %p at [%u]\n", iocb, tail); 1104 1105 /* 1106 * Check if the user asked us to deliver the result through an 1107 * eventfd. The eventfd_signal() function is safe to be called 1108 * from IRQ context. 1109 */ 1110 if (iocb->ki_eventfd != NULL) 1111 eventfd_signal(iocb->ki_eventfd, 1); 1112 1113 /* everything turned out well, dispose of the aiocb. */ 1114 kiocb_free(iocb); 1115 1116 /* 1117 * We have to order our ring_info tail store above and test 1118 * of the wait list below outside the wait lock. This is 1119 * like in wake_up_bit() where clearing a bit has to be 1120 * ordered with the unlocked test. 1121 */ 1122 smp_mb(); 1123 1124 if (waitqueue_active(&ctx->wait)) 1125 wake_up(&ctx->wait); 1126 1127 percpu_ref_put(&ctx->reqs); 1128 } 1129 EXPORT_SYMBOL(aio_complete); 1130 1131 /* aio_read_events_ring 1132 * Pull an event off of the ioctx's event ring. Returns the number of 1133 * events fetched 1134 */ 1135 static long aio_read_events_ring(struct kioctx *ctx, 1136 struct io_event __user *event, long nr) 1137 { 1138 struct aio_ring *ring; 1139 unsigned head, tail, pos; 1140 long ret = 0; 1141 int copy_ret; 1142 1143 /* 1144 * The mutex can block and wake us up and that will cause 1145 * wait_event_interruptible_hrtimeout() to schedule without sleeping 1146 * and repeat. This should be rare enough that it doesn't cause 1147 * peformance issues. See the comment in read_events() for more detail. 1148 */ 1149 sched_annotate_sleep(); 1150 mutex_lock(&ctx->ring_lock); 1151 1152 /* Access to ->ring_pages here is protected by ctx->ring_lock. */ 1153 ring = kmap_atomic(ctx->ring_pages[0]); 1154 head = ring->head; 1155 tail = ring->tail; 1156 kunmap_atomic(ring); 1157 1158 /* 1159 * Ensure that once we've read the current tail pointer, that 1160 * we also see the events that were stored up to the tail. 1161 */ 1162 smp_rmb(); 1163 1164 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events); 1165 1166 if (head == tail) 1167 goto out; 1168 1169 head %= ctx->nr_events; 1170 tail %= ctx->nr_events; 1171 1172 while (ret < nr) { 1173 long avail; 1174 struct io_event *ev; 1175 struct page *page; 1176 1177 avail = (head <= tail ? tail : ctx->nr_events) - head; 1178 if (head == tail) 1179 break; 1180 1181 avail = min(avail, nr - ret); 1182 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - 1183 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE)); 1184 1185 pos = head + AIO_EVENTS_OFFSET; 1186 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]; 1187 pos %= AIO_EVENTS_PER_PAGE; 1188 1189 ev = kmap(page); 1190 copy_ret = copy_to_user(event + ret, ev + pos, 1191 sizeof(*ev) * avail); 1192 kunmap(page); 1193 1194 if (unlikely(copy_ret)) { 1195 ret = -EFAULT; 1196 goto out; 1197 } 1198 1199 ret += avail; 1200 head += avail; 1201 head %= ctx->nr_events; 1202 } 1203 1204 ring = kmap_atomic(ctx->ring_pages[0]); 1205 ring->head = head; 1206 kunmap_atomic(ring); 1207 flush_dcache_page(ctx->ring_pages[0]); 1208 1209 pr_debug("%li h%u t%u\n", ret, head, tail); 1210 out: 1211 mutex_unlock(&ctx->ring_lock); 1212 1213 return ret; 1214 } 1215 1216 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr, 1217 struct io_event __user *event, long *i) 1218 { 1219 long ret = aio_read_events_ring(ctx, event + *i, nr - *i); 1220 1221 if (ret > 0) 1222 *i += ret; 1223 1224 if (unlikely(atomic_read(&ctx->dead))) 1225 ret = -EINVAL; 1226 1227 if (!*i) 1228 *i = ret; 1229 1230 return ret < 0 || *i >= min_nr; 1231 } 1232 1233 static long read_events(struct kioctx *ctx, long min_nr, long nr, 1234 struct io_event __user *event, 1235 struct timespec __user *timeout) 1236 { 1237 ktime_t until = { .tv64 = KTIME_MAX }; 1238 long ret = 0; 1239 1240 if (timeout) { 1241 struct timespec ts; 1242 1243 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) 1244 return -EFAULT; 1245 1246 until = timespec_to_ktime(ts); 1247 } 1248 1249 /* 1250 * Note that aio_read_events() is being called as the conditional - i.e. 1251 * we're calling it after prepare_to_wait() has set task state to 1252 * TASK_INTERRUPTIBLE. 1253 * 1254 * But aio_read_events() can block, and if it blocks it's going to flip 1255 * the task state back to TASK_RUNNING. 1256 * 1257 * This should be ok, provided it doesn't flip the state back to 1258 * TASK_RUNNING and return 0 too much - that causes us to spin. That 1259 * will only happen if the mutex_lock() call blocks, and we then find 1260 * the ringbuffer empty. So in practice we should be ok, but it's 1261 * something to be aware of when touching this code. 1262 */ 1263 if (until.tv64 == 0) 1264 aio_read_events(ctx, min_nr, nr, event, &ret); 1265 else 1266 wait_event_interruptible_hrtimeout(ctx->wait, 1267 aio_read_events(ctx, min_nr, nr, event, &ret), 1268 until); 1269 1270 if (!ret && signal_pending(current)) 1271 ret = -EINTR; 1272 1273 return ret; 1274 } 1275 1276 /* sys_io_setup: 1277 * Create an aio_context capable of receiving at least nr_events. 1278 * ctxp must not point to an aio_context that already exists, and 1279 * must be initialized to 0 prior to the call. On successful 1280 * creation of the aio_context, *ctxp is filled in with the resulting 1281 * handle. May fail with -EINVAL if *ctxp is not initialized, 1282 * if the specified nr_events exceeds internal limits. May fail 1283 * with -EAGAIN if the specified nr_events exceeds the user's limit 1284 * of available events. May fail with -ENOMEM if insufficient kernel 1285 * resources are available. May fail with -EFAULT if an invalid 1286 * pointer is passed for ctxp. Will fail with -ENOSYS if not 1287 * implemented. 1288 */ 1289 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp) 1290 { 1291 struct kioctx *ioctx = NULL; 1292 unsigned long ctx; 1293 long ret; 1294 1295 ret = get_user(ctx, ctxp); 1296 if (unlikely(ret)) 1297 goto out; 1298 1299 ret = -EINVAL; 1300 if (unlikely(ctx || nr_events == 0)) { 1301 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n", 1302 ctx, nr_events); 1303 goto out; 1304 } 1305 1306 ioctx = ioctx_alloc(nr_events); 1307 ret = PTR_ERR(ioctx); 1308 if (!IS_ERR(ioctx)) { 1309 ret = put_user(ioctx->user_id, ctxp); 1310 if (ret) 1311 kill_ioctx(current->mm, ioctx, NULL); 1312 percpu_ref_put(&ioctx->users); 1313 } 1314 1315 out: 1316 return ret; 1317 } 1318 1319 /* sys_io_destroy: 1320 * Destroy the aio_context specified. May cancel any outstanding 1321 * AIOs and block on completion. Will fail with -ENOSYS if not 1322 * implemented. May fail with -EINVAL if the context pointed to 1323 * is invalid. 1324 */ 1325 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx) 1326 { 1327 struct kioctx *ioctx = lookup_ioctx(ctx); 1328 if (likely(NULL != ioctx)) { 1329 struct completion requests_done = 1330 COMPLETION_INITIALIZER_ONSTACK(requests_done); 1331 int ret; 1332 1333 /* Pass requests_done to kill_ioctx() where it can be set 1334 * in a thread-safe way. If we try to set it here then we have 1335 * a race condition if two io_destroy() called simultaneously. 1336 */ 1337 ret = kill_ioctx(current->mm, ioctx, &requests_done); 1338 percpu_ref_put(&ioctx->users); 1339 1340 /* Wait until all IO for the context are done. Otherwise kernel 1341 * keep using user-space buffers even if user thinks the context 1342 * is destroyed. 1343 */ 1344 if (!ret) 1345 wait_for_completion(&requests_done); 1346 1347 return ret; 1348 } 1349 pr_debug("EINVAL: io_destroy: invalid context id\n"); 1350 return -EINVAL; 1351 } 1352 1353 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *, 1354 unsigned long, loff_t); 1355 typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *); 1356 1357 static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb, 1358 int rw, char __user *buf, 1359 unsigned long *nr_segs, 1360 struct iovec **iovec, 1361 bool compat) 1362 { 1363 ssize_t ret; 1364 1365 *nr_segs = kiocb->ki_nbytes; 1366 1367 #ifdef CONFIG_COMPAT 1368 if (compat) 1369 ret = compat_rw_copy_check_uvector(rw, 1370 (struct compat_iovec __user *)buf, 1371 *nr_segs, UIO_FASTIOV, *iovec, iovec); 1372 else 1373 #endif 1374 ret = rw_copy_check_uvector(rw, 1375 (struct iovec __user *)buf, 1376 *nr_segs, UIO_FASTIOV, *iovec, iovec); 1377 if (ret < 0) 1378 return ret; 1379 1380 /* ki_nbytes now reflect bytes instead of segs */ 1381 kiocb->ki_nbytes = ret; 1382 return 0; 1383 } 1384 1385 static ssize_t aio_setup_single_vector(struct kiocb *kiocb, 1386 int rw, char __user *buf, 1387 unsigned long *nr_segs, 1388 struct iovec *iovec) 1389 { 1390 if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes))) 1391 return -EFAULT; 1392 1393 iovec->iov_base = buf; 1394 iovec->iov_len = kiocb->ki_nbytes; 1395 *nr_segs = 1; 1396 return 0; 1397 } 1398 1399 /* 1400 * aio_run_iocb: 1401 * Performs the initial checks and io submission. 1402 */ 1403 static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode, 1404 char __user *buf, bool compat) 1405 { 1406 struct file *file = req->ki_filp; 1407 ssize_t ret; 1408 unsigned long nr_segs; 1409 int rw; 1410 fmode_t mode; 1411 aio_rw_op *rw_op; 1412 rw_iter_op *iter_op; 1413 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; 1414 struct iov_iter iter; 1415 1416 switch (opcode) { 1417 case IOCB_CMD_PREAD: 1418 case IOCB_CMD_PREADV: 1419 mode = FMODE_READ; 1420 rw = READ; 1421 rw_op = file->f_op->aio_read; 1422 iter_op = file->f_op->read_iter; 1423 goto rw_common; 1424 1425 case IOCB_CMD_PWRITE: 1426 case IOCB_CMD_PWRITEV: 1427 mode = FMODE_WRITE; 1428 rw = WRITE; 1429 rw_op = file->f_op->aio_write; 1430 iter_op = file->f_op->write_iter; 1431 goto rw_common; 1432 rw_common: 1433 if (unlikely(!(file->f_mode & mode))) 1434 return -EBADF; 1435 1436 if (!rw_op && !iter_op) 1437 return -EINVAL; 1438 1439 ret = (opcode == IOCB_CMD_PREADV || 1440 opcode == IOCB_CMD_PWRITEV) 1441 ? aio_setup_vectored_rw(req, rw, buf, &nr_segs, 1442 &iovec, compat) 1443 : aio_setup_single_vector(req, rw, buf, &nr_segs, 1444 iovec); 1445 if (!ret) 1446 ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes); 1447 if (ret < 0) { 1448 if (iovec != inline_vecs) 1449 kfree(iovec); 1450 return ret; 1451 } 1452 1453 req->ki_nbytes = ret; 1454 1455 /* XXX: move/kill - rw_verify_area()? */ 1456 /* This matches the pread()/pwrite() logic */ 1457 if (req->ki_pos < 0) { 1458 ret = -EINVAL; 1459 break; 1460 } 1461 1462 if (rw == WRITE) 1463 file_start_write(file); 1464 1465 if (iter_op) { 1466 iov_iter_init(&iter, rw, iovec, nr_segs, req->ki_nbytes); 1467 ret = iter_op(req, &iter); 1468 } else { 1469 ret = rw_op(req, iovec, nr_segs, req->ki_pos); 1470 } 1471 1472 if (rw == WRITE) 1473 file_end_write(file); 1474 break; 1475 1476 case IOCB_CMD_FDSYNC: 1477 if (!file->f_op->aio_fsync) 1478 return -EINVAL; 1479 1480 ret = file->f_op->aio_fsync(req, 1); 1481 break; 1482 1483 case IOCB_CMD_FSYNC: 1484 if (!file->f_op->aio_fsync) 1485 return -EINVAL; 1486 1487 ret = file->f_op->aio_fsync(req, 0); 1488 break; 1489 1490 default: 1491 pr_debug("EINVAL: no operation provided\n"); 1492 return -EINVAL; 1493 } 1494 1495 if (iovec != inline_vecs) 1496 kfree(iovec); 1497 1498 if (ret != -EIOCBQUEUED) { 1499 /* 1500 * There's no easy way to restart the syscall since other AIO's 1501 * may be already running. Just fail this IO with EINTR. 1502 */ 1503 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR || 1504 ret == -ERESTARTNOHAND || 1505 ret == -ERESTART_RESTARTBLOCK)) 1506 ret = -EINTR; 1507 aio_complete(req, ret, 0); 1508 } 1509 1510 return 0; 1511 } 1512 1513 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1514 struct iocb *iocb, bool compat) 1515 { 1516 struct kiocb *req; 1517 ssize_t ret; 1518 1519 /* enforce forwards compatibility on users */ 1520 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) { 1521 pr_debug("EINVAL: reserve field set\n"); 1522 return -EINVAL; 1523 } 1524 1525 /* prevent overflows */ 1526 if (unlikely( 1527 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1528 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1529 ((ssize_t)iocb->aio_nbytes < 0) 1530 )) { 1531 pr_debug("EINVAL: io_submit: overflow check\n"); 1532 return -EINVAL; 1533 } 1534 1535 req = aio_get_req(ctx); 1536 if (unlikely(!req)) 1537 return -EAGAIN; 1538 1539 req->ki_filp = fget(iocb->aio_fildes); 1540 if (unlikely(!req->ki_filp)) { 1541 ret = -EBADF; 1542 goto out_put_req; 1543 } 1544 1545 if (iocb->aio_flags & IOCB_FLAG_RESFD) { 1546 /* 1547 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an 1548 * instance of the file* now. The file descriptor must be 1549 * an eventfd() fd, and will be signaled for each completed 1550 * event using the eventfd_signal() function. 1551 */ 1552 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd); 1553 if (IS_ERR(req->ki_eventfd)) { 1554 ret = PTR_ERR(req->ki_eventfd); 1555 req->ki_eventfd = NULL; 1556 goto out_put_req; 1557 } 1558 } 1559 1560 ret = put_user(KIOCB_KEY, &user_iocb->aio_key); 1561 if (unlikely(ret)) { 1562 pr_debug("EFAULT: aio_key\n"); 1563 goto out_put_req; 1564 } 1565 1566 req->ki_obj.user = user_iocb; 1567 req->ki_user_data = iocb->aio_data; 1568 req->ki_pos = iocb->aio_offset; 1569 req->ki_nbytes = iocb->aio_nbytes; 1570 1571 ret = aio_run_iocb(req, iocb->aio_lio_opcode, 1572 (char __user *)(unsigned long)iocb->aio_buf, 1573 compat); 1574 if (ret) 1575 goto out_put_req; 1576 1577 return 0; 1578 out_put_req: 1579 put_reqs_available(ctx, 1); 1580 percpu_ref_put(&ctx->reqs); 1581 kiocb_free(req); 1582 return ret; 1583 } 1584 1585 long do_io_submit(aio_context_t ctx_id, long nr, 1586 struct iocb __user *__user *iocbpp, bool compat) 1587 { 1588 struct kioctx *ctx; 1589 long ret = 0; 1590 int i = 0; 1591 struct blk_plug plug; 1592 1593 if (unlikely(nr < 0)) 1594 return -EINVAL; 1595 1596 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp))) 1597 nr = LONG_MAX/sizeof(*iocbpp); 1598 1599 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1600 return -EFAULT; 1601 1602 ctx = lookup_ioctx(ctx_id); 1603 if (unlikely(!ctx)) { 1604 pr_debug("EINVAL: invalid context id\n"); 1605 return -EINVAL; 1606 } 1607 1608 blk_start_plug(&plug); 1609 1610 /* 1611 * AKPM: should this return a partial result if some of the IOs were 1612 * successfully submitted? 1613 */ 1614 for (i=0; i<nr; i++) { 1615 struct iocb __user *user_iocb; 1616 struct iocb tmp; 1617 1618 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1619 ret = -EFAULT; 1620 break; 1621 } 1622 1623 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1624 ret = -EFAULT; 1625 break; 1626 } 1627 1628 ret = io_submit_one(ctx, user_iocb, &tmp, compat); 1629 if (ret) 1630 break; 1631 } 1632 blk_finish_plug(&plug); 1633 1634 percpu_ref_put(&ctx->users); 1635 return i ? i : ret; 1636 } 1637 1638 /* sys_io_submit: 1639 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1640 * the number of iocbs queued. May return -EINVAL if the aio_context 1641 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1642 * *iocbpp[0] is not properly initialized, if the operation specified 1643 * is invalid for the file descriptor in the iocb. May fail with 1644 * -EFAULT if any of the data structures point to invalid data. May 1645 * fail with -EBADF if the file descriptor specified in the first 1646 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1647 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1648 * fail with -ENOSYS if not implemented. 1649 */ 1650 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, 1651 struct iocb __user * __user *, iocbpp) 1652 { 1653 return do_io_submit(ctx_id, nr, iocbpp, 0); 1654 } 1655 1656 /* lookup_kiocb 1657 * Finds a given iocb for cancellation. 1658 */ 1659 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 1660 u32 key) 1661 { 1662 struct list_head *pos; 1663 1664 assert_spin_locked(&ctx->ctx_lock); 1665 1666 if (key != KIOCB_KEY) 1667 return NULL; 1668 1669 /* TODO: use a hash or array, this sucks. */ 1670 list_for_each(pos, &ctx->active_reqs) { 1671 struct kiocb *kiocb = list_kiocb(pos); 1672 if (kiocb->ki_obj.user == iocb) 1673 return kiocb; 1674 } 1675 return NULL; 1676 } 1677 1678 /* sys_io_cancel: 1679 * Attempts to cancel an iocb previously passed to io_submit. If 1680 * the operation is successfully cancelled, the resulting event is 1681 * copied into the memory pointed to by result without being placed 1682 * into the completion queue and 0 is returned. May fail with 1683 * -EFAULT if any of the data structures pointed to are invalid. 1684 * May fail with -EINVAL if aio_context specified by ctx_id is 1685 * invalid. May fail with -EAGAIN if the iocb specified was not 1686 * cancelled. Will fail with -ENOSYS if not implemented. 1687 */ 1688 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, 1689 struct io_event __user *, result) 1690 { 1691 struct kioctx *ctx; 1692 struct kiocb *kiocb; 1693 u32 key; 1694 int ret; 1695 1696 ret = get_user(key, &iocb->aio_key); 1697 if (unlikely(ret)) 1698 return -EFAULT; 1699 1700 ctx = lookup_ioctx(ctx_id); 1701 if (unlikely(!ctx)) 1702 return -EINVAL; 1703 1704 spin_lock_irq(&ctx->ctx_lock); 1705 1706 kiocb = lookup_kiocb(ctx, iocb, key); 1707 if (kiocb) 1708 ret = kiocb_cancel(kiocb); 1709 else 1710 ret = -EINVAL; 1711 1712 spin_unlock_irq(&ctx->ctx_lock); 1713 1714 if (!ret) { 1715 /* 1716 * The result argument is no longer used - the io_event is 1717 * always delivered via the ring buffer. -EINPROGRESS indicates 1718 * cancellation is progress: 1719 */ 1720 ret = -EINPROGRESS; 1721 } 1722 1723 percpu_ref_put(&ctx->users); 1724 1725 return ret; 1726 } 1727 1728 /* io_getevents: 1729 * Attempts to read at least min_nr events and up to nr events from 1730 * the completion queue for the aio_context specified by ctx_id. If 1731 * it succeeds, the number of read events is returned. May fail with 1732 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is 1733 * out of range, if timeout is out of range. May fail with -EFAULT 1734 * if any of the memory specified is invalid. May return 0 or 1735 * < min_nr if the timeout specified by timeout has elapsed 1736 * before sufficient events are available, where timeout == NULL 1737 * specifies an infinite timeout. Note that the timeout pointed to by 1738 * timeout is relative. Will fail with -ENOSYS if not implemented. 1739 */ 1740 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, 1741 long, min_nr, 1742 long, nr, 1743 struct io_event __user *, events, 1744 struct timespec __user *, timeout) 1745 { 1746 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1747 long ret = -EINVAL; 1748 1749 if (likely(ioctx)) { 1750 if (likely(min_nr <= nr && min_nr >= 0)) 1751 ret = read_events(ioctx, min_nr, nr, events, timeout); 1752 percpu_ref_put(&ioctx->users); 1753 } 1754 return ret; 1755 } 1756