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