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 52struct 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 70struct kioctx_table { 71 struct rcu_head rcu; 72 unsigned nr; 73 struct kioctx *table[]; 74}; 75 76struct kioctx_cpu { 77 unsigned reqs_available; 78}; 79 80struct ctx_rq_wait { 81 struct completion comp; 82 atomic_t count; 83}; 84 85struct kioctx { 86 struct percpu_ref users; 87 atomic_t dead; 88 89 struct percpu_ref reqs; 90 91 unsigned long user_id; 92 93 struct __percpu kioctx_cpu *cpu; 94 95 /* 96 * For percpu reqs_available, number of slots we move to/from global 97 * counter at a time: 98 */ 99 unsigned req_batch; 100 /* 101 * This is what userspace passed to io_setup(), it's not used for 102 * anything but counting against the global max_reqs quota. 103 * 104 * The real limit is nr_events - 1, which will be larger (see 105 * aio_setup_ring()) 106 */ 107 unsigned max_reqs; 108 109 /* Size of ringbuffer, in units of struct io_event */ 110 unsigned nr_events; 111 112 unsigned long mmap_base; 113 unsigned long mmap_size; 114 115 struct page **ring_pages; 116 long nr_pages; 117 118 struct work_struct free_work; 119 120 /* 121 * signals when all in-flight requests are done 122 */ 123 struct ctx_rq_wait *rq_wait; 124 125 struct { 126 /* 127 * This counts the number of available slots in the ringbuffer, 128 * so we avoid overflowing it: it's decremented (if positive) 129 * when allocating a kiocb and incremented when the resulting 130 * io_event is pulled off the ringbuffer. 131 * 132 * We batch accesses to it with a percpu version. 133 */ 134 atomic_t reqs_available; 135 } ____cacheline_aligned_in_smp; 136 137 struct { 138 spinlock_t ctx_lock; 139 struct list_head active_reqs; /* used for cancellation */ 140 } ____cacheline_aligned_in_smp; 141 142 struct { 143 struct mutex ring_lock; 144 wait_queue_head_t wait; 145 } ____cacheline_aligned_in_smp; 146 147 struct { 148 unsigned tail; 149 unsigned completed_events; 150 spinlock_t completion_lock; 151 } ____cacheline_aligned_in_smp; 152 153 struct page *internal_pages[AIO_RING_PAGES]; 154 struct file *aio_ring_file; 155 156 unsigned id; 157}; 158 159/* 160 * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either 161 * cancelled or completed (this makes a certain amount of sense because 162 * successful cancellation - io_cancel() - does deliver the completion to 163 * userspace). 164 * 165 * And since most things don't implement kiocb cancellation and we'd really like 166 * kiocb completion to be lockless when possible, we use ki_cancel to 167 * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED 168 * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel(). 169 */ 170#define KIOCB_CANCELLED ((void *) (~0ULL)) 171 172struct aio_kiocb { 173 struct kiocb common; 174 175 struct kioctx *ki_ctx; 176 kiocb_cancel_fn *ki_cancel; 177 178 struct iocb __user *ki_user_iocb; /* user's aiocb */ 179 __u64 ki_user_data; /* user's data for completion */ 180 181 struct list_head ki_list; /* the aio core uses this 182 * for cancellation */ 183 184 /* 185 * If the aio_resfd field of the userspace iocb is not zero, 186 * this is the underlying eventfd context to deliver events to. 187 */ 188 struct eventfd_ctx *ki_eventfd; 189}; 190 191/*------ sysctl variables----*/ 192static DEFINE_SPINLOCK(aio_nr_lock); 193unsigned long aio_nr; /* current system wide number of aio requests */ 194unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ 195/*----end sysctl variables---*/ 196 197static struct kmem_cache *kiocb_cachep; 198static struct kmem_cache *kioctx_cachep; 199 200static struct vfsmount *aio_mnt; 201 202static const struct file_operations aio_ring_fops; 203static const struct address_space_operations aio_ctx_aops; 204 205static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages) 206{ 207 struct qstr this = QSTR_INIT("[aio]", 5); 208 struct file *file; 209 struct path path; 210 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb); 211 if (IS_ERR(inode)) 212 return ERR_CAST(inode); 213 214 inode->i_mapping->a_ops = &aio_ctx_aops; 215 inode->i_mapping->private_data = ctx; 216 inode->i_size = PAGE_SIZE * nr_pages; 217 218 path.dentry = d_alloc_pseudo(aio_mnt->mnt_sb, &this); 219 if (!path.dentry) { 220 iput(inode); 221 return ERR_PTR(-ENOMEM); 222 } 223 path.mnt = mntget(aio_mnt); 224 225 d_instantiate(path.dentry, inode); 226 file = alloc_file(&path, FMODE_READ | FMODE_WRITE, &aio_ring_fops); 227 if (IS_ERR(file)) { 228 path_put(&path); 229 return file; 230 } 231 232 file->f_flags = O_RDWR; 233 return file; 234} 235 236static struct dentry *aio_mount(struct file_system_type *fs_type, 237 int flags, const char *dev_name, void *data) 238{ 239 static const struct dentry_operations ops = { 240 .d_dname = simple_dname, 241 }; 242 return mount_pseudo(fs_type, "aio:", NULL, &ops, AIO_RING_MAGIC); 243} 244 245/* aio_setup 246 * Creates the slab caches used by the aio routines, panic on 247 * failure as this is done early during the boot sequence. 248 */ 249static int __init aio_setup(void) 250{ 251 static struct file_system_type aio_fs = { 252 .name = "aio", 253 .mount = aio_mount, 254 .kill_sb = kill_anon_super, 255 }; 256 aio_mnt = kern_mount(&aio_fs); 257 if (IS_ERR(aio_mnt)) 258 panic("Failed to create aio fs mount."); 259 260 kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); 261 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); 262 263 pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page)); 264 265 return 0; 266} 267__initcall(aio_setup); 268 269static void put_aio_ring_file(struct kioctx *ctx) 270{ 271 struct file *aio_ring_file = ctx->aio_ring_file; 272 if (aio_ring_file) { 273 truncate_setsize(aio_ring_file->f_inode, 0); 274 275 /* Prevent further access to the kioctx from migratepages */ 276 spin_lock(&aio_ring_file->f_inode->i_mapping->private_lock); 277 aio_ring_file->f_inode->i_mapping->private_data = NULL; 278 ctx->aio_ring_file = NULL; 279 spin_unlock(&aio_ring_file->f_inode->i_mapping->private_lock); 280 281 fput(aio_ring_file); 282 } 283} 284 285static void aio_free_ring(struct kioctx *ctx) 286{ 287 int i; 288 289 /* Disconnect the kiotx from the ring file. This prevents future 290 * accesses to the kioctx from page migration. 291 */ 292 put_aio_ring_file(ctx); 293 294 for (i = 0; i < ctx->nr_pages; i++) { 295 struct page *page; 296 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i, 297 page_count(ctx->ring_pages[i])); 298 page = ctx->ring_pages[i]; 299 if (!page) 300 continue; 301 ctx->ring_pages[i] = NULL; 302 put_page(page); 303 } 304 305 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) { 306 kfree(ctx->ring_pages); 307 ctx->ring_pages = NULL; 308 } 309} 310 311static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma) 312{ 313 vma->vm_flags |= VM_DONTEXPAND; 314 vma->vm_ops = &generic_file_vm_ops; 315 return 0; 316} 317 318static int aio_ring_remap(struct file *file, struct vm_area_struct *vma) 319{ 320 struct mm_struct *mm = vma->vm_mm; 321 struct kioctx_table *table; 322 int i, res = -EINVAL; 323 324 spin_lock(&mm->ioctx_lock); 325 rcu_read_lock(); 326 table = rcu_dereference(mm->ioctx_table); 327 for (i = 0; i < table->nr; i++) { 328 struct kioctx *ctx; 329 330 ctx = table->table[i]; 331 if (ctx && ctx->aio_ring_file == file) { 332 if (!atomic_read(&ctx->dead)) { 333 ctx->user_id = ctx->mmap_base = vma->vm_start; 334 res = 0; 335 } 336 break; 337 } 338 } 339 340 rcu_read_unlock(); 341 spin_unlock(&mm->ioctx_lock); 342 return res; 343} 344 345static const struct file_operations aio_ring_fops = { 346 .mmap = aio_ring_mmap, 347 .mremap = aio_ring_remap, 348}; 349 350#if IS_ENABLED(CONFIG_MIGRATION) 351static int aio_migratepage(struct address_space *mapping, struct page *new, 352 struct page *old, enum migrate_mode mode) 353{ 354 struct kioctx *ctx; 355 unsigned long flags; 356 pgoff_t idx; 357 int rc; 358 359 rc = 0; 360 361 /* mapping->private_lock here protects against the kioctx teardown. */ 362 spin_lock(&mapping->private_lock); 363 ctx = mapping->private_data; 364 if (!ctx) { 365 rc = -EINVAL; 366 goto out; 367 } 368 369 /* The ring_lock mutex. The prevents aio_read_events() from writing 370 * to the ring's head, and prevents page migration from mucking in 371 * a partially initialized kiotx. 372 */ 373 if (!mutex_trylock(&ctx->ring_lock)) { 374 rc = -EAGAIN; 375 goto out; 376 } 377 378 idx = old->index; 379 if (idx < (pgoff_t)ctx->nr_pages) { 380 /* Make sure the old page hasn't already been changed */ 381 if (ctx->ring_pages[idx] != old) 382 rc = -EAGAIN; 383 } else 384 rc = -EINVAL; 385 386 if (rc != 0) 387 goto out_unlock; 388 389 /* Writeback must be complete */ 390 BUG_ON(PageWriteback(old)); 391 get_page(new); 392 393 rc = migrate_page_move_mapping(mapping, new, old, NULL, mode, 1); 394 if (rc != MIGRATEPAGE_SUCCESS) { 395 put_page(new); 396 goto out_unlock; 397 } 398 399 /* Take completion_lock to prevent other writes to the ring buffer 400 * while the old page is copied to the new. This prevents new 401 * events from being lost. 402 */ 403 spin_lock_irqsave(&ctx->completion_lock, flags); 404 migrate_page_copy(new, old); 405 BUG_ON(ctx->ring_pages[idx] != old); 406 ctx->ring_pages[idx] = new; 407 spin_unlock_irqrestore(&ctx->completion_lock, flags); 408 409 /* The old page is no longer accessible. */ 410 put_page(old); 411 412out_unlock: 413 mutex_unlock(&ctx->ring_lock); 414out: 415 spin_unlock(&mapping->private_lock); 416 return rc; 417} 418#endif 419 420static const struct address_space_operations aio_ctx_aops = { 421 .set_page_dirty = __set_page_dirty_no_writeback, 422#if IS_ENABLED(CONFIG_MIGRATION) 423 .migratepage = aio_migratepage, 424#endif 425}; 426 427static int aio_setup_ring(struct kioctx *ctx) 428{ 429 struct aio_ring *ring; 430 unsigned nr_events = ctx->max_reqs; 431 struct mm_struct *mm = current->mm; 432 unsigned long size, unused; 433 int nr_pages; 434 int i; 435 struct file *file; 436 437 /* Compensate for the ring buffer's head/tail overlap entry */ 438 nr_events += 2; /* 1 is required, 2 for good luck */ 439 440 size = sizeof(struct aio_ring); 441 size += sizeof(struct io_event) * nr_events; 442 443 nr_pages = PFN_UP(size); 444 if (nr_pages < 0) 445 return -EINVAL; 446 447 file = aio_private_file(ctx, nr_pages); 448 if (IS_ERR(file)) { 449 ctx->aio_ring_file = NULL; 450 return -ENOMEM; 451 } 452 453 ctx->aio_ring_file = file; 454 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) 455 / sizeof(struct io_event); 456 457 ctx->ring_pages = ctx->internal_pages; 458 if (nr_pages > AIO_RING_PAGES) { 459 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *), 460 GFP_KERNEL); 461 if (!ctx->ring_pages) { 462 put_aio_ring_file(ctx); 463 return -ENOMEM; 464 } 465 } 466 467 for (i = 0; i < nr_pages; i++) { 468 struct page *page; 469 page = find_or_create_page(file->f_inode->i_mapping, 470 i, GFP_HIGHUSER | __GFP_ZERO); 471 if (!page) 472 break; 473 pr_debug("pid(%d) page[%d]->count=%d\n", 474 current->pid, i, page_count(page)); 475 SetPageUptodate(page); 476 unlock_page(page); 477 478 ctx->ring_pages[i] = page; 479 } 480 ctx->nr_pages = i; 481 482 if (unlikely(i != nr_pages)) { 483 aio_free_ring(ctx); 484 return -ENOMEM; 485 } 486 487 ctx->mmap_size = nr_pages * PAGE_SIZE; 488 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size); 489 490 down_write(&mm->mmap_sem); 491 ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size, 492 PROT_READ | PROT_WRITE, 493 MAP_SHARED, 0, &unused); 494 up_write(&mm->mmap_sem); 495 if (IS_ERR((void *)ctx->mmap_base)) { 496 ctx->mmap_size = 0; 497 aio_free_ring(ctx); 498 return -ENOMEM; 499 } 500 501 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base); 502 503 ctx->user_id = ctx->mmap_base; 504 ctx->nr_events = nr_events; /* trusted copy */ 505 506 ring = kmap_atomic(ctx->ring_pages[0]); 507 ring->nr = nr_events; /* user copy */ 508 ring->id = ~0U; 509 ring->head = ring->tail = 0; 510 ring->magic = AIO_RING_MAGIC; 511 ring->compat_features = AIO_RING_COMPAT_FEATURES; 512 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; 513 ring->header_length = sizeof(struct aio_ring); 514 kunmap_atomic(ring); 515 flush_dcache_page(ctx->ring_pages[0]); 516 517 return 0; 518} 519 520#define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) 521#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) 522#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) 523 524void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) 525{ 526 struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common); 527 struct kioctx *ctx = req->ki_ctx; 528 unsigned long flags; 529 530 spin_lock_irqsave(&ctx->ctx_lock, flags); 531 532 if (!req->ki_list.next) 533 list_add(&req->ki_list, &ctx->active_reqs); 534 535 req->ki_cancel = cancel; 536 537 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 538} 539EXPORT_SYMBOL(kiocb_set_cancel_fn); 540 541static int kiocb_cancel(struct aio_kiocb *kiocb) 542{ 543 kiocb_cancel_fn *old, *cancel; 544 545 /* 546 * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it 547 * actually has a cancel function, hence the cmpxchg() 548 */ 549 550 cancel = ACCESS_ONCE(kiocb->ki_cancel); 551 do { 552 if (!cancel || cancel == KIOCB_CANCELLED) 553 return -EINVAL; 554 555 old = cancel; 556 cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED); 557 } while (cancel != old); 558 559 return cancel(&kiocb->common); 560} 561 562static void free_ioctx(struct work_struct *work) 563{ 564 struct kioctx *ctx = container_of(work, struct kioctx, free_work); 565 566 pr_debug("freeing %p\n", ctx); 567 568 aio_free_ring(ctx); 569 free_percpu(ctx->cpu); 570 percpu_ref_exit(&ctx->reqs); 571 percpu_ref_exit(&ctx->users); 572 kmem_cache_free(kioctx_cachep, ctx); 573} 574 575static void free_ioctx_reqs(struct percpu_ref *ref) 576{ 577 struct kioctx *ctx = container_of(ref, struct kioctx, reqs); 578 579 /* At this point we know that there are no any in-flight requests */ 580 if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count)) 581 complete(&ctx->rq_wait->comp); 582 583 INIT_WORK(&ctx->free_work, free_ioctx); 584 schedule_work(&ctx->free_work); 585} 586 587/* 588 * When this function runs, the kioctx has been removed from the "hash table" 589 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted - 590 * now it's safe to cancel any that need to be. 591 */ 592static void free_ioctx_users(struct percpu_ref *ref) 593{ 594 struct kioctx *ctx = container_of(ref, struct kioctx, users); 595 struct aio_kiocb *req; 596 597 spin_lock_irq(&ctx->ctx_lock); 598 599 while (!list_empty(&ctx->active_reqs)) { 600 req = list_first_entry(&ctx->active_reqs, 601 struct aio_kiocb, ki_list); 602 603 list_del_init(&req->ki_list); 604 kiocb_cancel(req); 605 } 606 607 spin_unlock_irq(&ctx->ctx_lock); 608 609 percpu_ref_kill(&ctx->reqs); 610 percpu_ref_put(&ctx->reqs); 611} 612 613static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) 614{ 615 unsigned i, new_nr; 616 struct kioctx_table *table, *old; 617 struct aio_ring *ring; 618 619 spin_lock(&mm->ioctx_lock); 620 table = rcu_dereference_raw(mm->ioctx_table); 621 622 while (1) { 623 if (table) 624 for (i = 0; i < table->nr; i++) 625 if (!table->table[i]) { 626 ctx->id = i; 627 table->table[i] = ctx; 628 spin_unlock(&mm->ioctx_lock); 629 630 /* While kioctx setup is in progress, 631 * we are protected from page migration 632 * changes ring_pages by ->ring_lock. 633 */ 634 ring = kmap_atomic(ctx->ring_pages[0]); 635 ring->id = ctx->id; 636 kunmap_atomic(ring); 637 return 0; 638 } 639 640 new_nr = (table ? table->nr : 1) * 4; 641 spin_unlock(&mm->ioctx_lock); 642 643 table = kzalloc(sizeof(*table) + sizeof(struct kioctx *) * 644 new_nr, GFP_KERNEL); 645 if (!table) 646 return -ENOMEM; 647 648 table->nr = new_nr; 649 650 spin_lock(&mm->ioctx_lock); 651 old = rcu_dereference_raw(mm->ioctx_table); 652 653 if (!old) { 654 rcu_assign_pointer(mm->ioctx_table, table); 655 } else if (table->nr > old->nr) { 656 memcpy(table->table, old->table, 657 old->nr * sizeof(struct kioctx *)); 658 659 rcu_assign_pointer(mm->ioctx_table, table); 660 kfree_rcu(old, rcu); 661 } else { 662 kfree(table); 663 table = old; 664 } 665 } 666} 667 668static void aio_nr_sub(unsigned nr) 669{ 670 spin_lock(&aio_nr_lock); 671 if (WARN_ON(aio_nr - nr > aio_nr)) 672 aio_nr = 0; 673 else 674 aio_nr -= nr; 675 spin_unlock(&aio_nr_lock); 676} 677 678/* ioctx_alloc 679 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. 680 */ 681static struct kioctx *ioctx_alloc(unsigned nr_events) 682{ 683 struct mm_struct *mm = current->mm; 684 struct kioctx *ctx; 685 int err = -ENOMEM; 686 687 /* 688 * We keep track of the number of available ringbuffer slots, to prevent 689 * overflow (reqs_available), and we also use percpu counters for this. 690 * 691 * So since up to half the slots might be on other cpu's percpu counters 692 * and unavailable, double nr_events so userspace sees what they 693 * expected: additionally, we move req_batch slots to/from percpu 694 * counters at a time, so make sure that isn't 0: 695 */ 696 nr_events = max(nr_events, num_possible_cpus() * 4); 697 nr_events *= 2; 698 699 /* Prevent overflows */ 700 if (nr_events > (0x10000000U / sizeof(struct io_event))) { 701 pr_debug("ENOMEM: nr_events too high\n"); 702 return ERR_PTR(-EINVAL); 703 } 704 705 if (!nr_events || (unsigned long)nr_events > (aio_max_nr * 2UL)) 706 return ERR_PTR(-EAGAIN); 707 708 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); 709 if (!ctx) 710 return ERR_PTR(-ENOMEM); 711 712 ctx->max_reqs = nr_events; 713 714 spin_lock_init(&ctx->ctx_lock); 715 spin_lock_init(&ctx->completion_lock); 716 mutex_init(&ctx->ring_lock); 717 /* Protect against page migration throughout kiotx setup by keeping 718 * the ring_lock mutex held until setup is complete. */ 719 mutex_lock(&ctx->ring_lock); 720 init_waitqueue_head(&ctx->wait); 721 722 INIT_LIST_HEAD(&ctx->active_reqs); 723 724 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL)) 725 goto err; 726 727 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL)) 728 goto err; 729 730 ctx->cpu = alloc_percpu(struct kioctx_cpu); 731 if (!ctx->cpu) 732 goto err; 733 734 err = aio_setup_ring(ctx); 735 if (err < 0) 736 goto err; 737 738 atomic_set(&ctx->reqs_available, ctx->nr_events - 1); 739 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4); 740 if (ctx->req_batch < 1) 741 ctx->req_batch = 1; 742 743 /* limit the number of system wide aios */ 744 spin_lock(&aio_nr_lock); 745 if (aio_nr + nr_events > (aio_max_nr * 2UL) || 746 aio_nr + nr_events < aio_nr) { 747 spin_unlock(&aio_nr_lock); 748 err = -EAGAIN; 749 goto err_ctx; 750 } 751 aio_nr += ctx->max_reqs; 752 spin_unlock(&aio_nr_lock); 753 754 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */ 755 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */ 756 757 err = ioctx_add_table(ctx, mm); 758 if (err) 759 goto err_cleanup; 760 761 /* Release the ring_lock mutex now that all setup is complete. */ 762 mutex_unlock(&ctx->ring_lock); 763 764 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", 765 ctx, ctx->user_id, mm, ctx->nr_events); 766 return ctx; 767 768err_cleanup: 769 aio_nr_sub(ctx->max_reqs); 770err_ctx: 771 atomic_set(&ctx->dead, 1); 772 if (ctx->mmap_size) 773 vm_munmap(ctx->mmap_base, ctx->mmap_size); 774 aio_free_ring(ctx); 775err: 776 mutex_unlock(&ctx->ring_lock); 777 free_percpu(ctx->cpu); 778 percpu_ref_exit(&ctx->reqs); 779 percpu_ref_exit(&ctx->users); 780 kmem_cache_free(kioctx_cachep, ctx); 781 pr_debug("error allocating ioctx %d\n", err); 782 return ERR_PTR(err); 783} 784 785/* kill_ioctx 786 * Cancels all outstanding aio requests on an aio context. Used 787 * when the processes owning a context have all exited to encourage 788 * the rapid destruction of the kioctx. 789 */ 790static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx, 791 struct ctx_rq_wait *wait) 792{ 793 struct kioctx_table *table; 794 795 spin_lock(&mm->ioctx_lock); 796 if (atomic_xchg(&ctx->dead, 1)) { 797 spin_unlock(&mm->ioctx_lock); 798 return -EINVAL; 799 } 800 801 table = rcu_dereference_raw(mm->ioctx_table); 802 WARN_ON(ctx != table->table[ctx->id]); 803 table->table[ctx->id] = NULL; 804 spin_unlock(&mm->ioctx_lock); 805 806 /* percpu_ref_kill() will do the necessary call_rcu() */ 807 wake_up_all(&ctx->wait); 808 809 /* 810 * It'd be more correct to do this in free_ioctx(), after all 811 * the outstanding kiocbs have finished - but by then io_destroy 812 * has already returned, so io_setup() could potentially return 813 * -EAGAIN with no ioctxs actually in use (as far as userspace 814 * could tell). 815 */ 816 aio_nr_sub(ctx->max_reqs); 817 818 if (ctx->mmap_size) 819 vm_munmap(ctx->mmap_base, ctx->mmap_size); 820 821 ctx->rq_wait = wait; 822 percpu_ref_kill(&ctx->users); 823 return 0; 824} 825 826/* 827 * exit_aio: called when the last user of mm goes away. At this point, there is 828 * no way for any new requests to be submited or any of the io_* syscalls to be 829 * called on the context. 830 * 831 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on 832 * them. 833 */ 834void exit_aio(struct mm_struct *mm) 835{ 836 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table); 837 struct ctx_rq_wait wait; 838 int i, skipped; 839 840 if (!table) 841 return; 842 843 atomic_set(&wait.count, table->nr); 844 init_completion(&wait.comp); 845 846 skipped = 0; 847 for (i = 0; i < table->nr; ++i) { 848 struct kioctx *ctx = table->table[i]; 849 850 if (!ctx) { 851 skipped++; 852 continue; 853 } 854 855 /* 856 * We don't need to bother with munmap() here - exit_mmap(mm) 857 * is coming and it'll unmap everything. And we simply can't, 858 * this is not necessarily our ->mm. 859 * Since kill_ioctx() uses non-zero ->mmap_size as indicator 860 * that it needs to unmap the area, just set it to 0. 861 */ 862 ctx->mmap_size = 0; 863 kill_ioctx(mm, ctx, &wait); 864 } 865 866 if (!atomic_sub_and_test(skipped, &wait.count)) { 867 /* Wait until all IO for the context are done. */ 868 wait_for_completion(&wait.comp); 869 } 870 871 RCU_INIT_POINTER(mm->ioctx_table, NULL); 872 kfree(table); 873} 874 875static void put_reqs_available(struct kioctx *ctx, unsigned nr) 876{ 877 struct kioctx_cpu *kcpu; 878 unsigned long flags; 879 880 local_irq_save(flags); 881 kcpu = this_cpu_ptr(ctx->cpu); 882 kcpu->reqs_available += nr; 883 884 while (kcpu->reqs_available >= ctx->req_batch * 2) { 885 kcpu->reqs_available -= ctx->req_batch; 886 atomic_add(ctx->req_batch, &ctx->reqs_available); 887 } 888 889 local_irq_restore(flags); 890} 891 892static bool get_reqs_available(struct kioctx *ctx) 893{ 894 struct kioctx_cpu *kcpu; 895 bool ret = false; 896 unsigned long flags; 897 898 local_irq_save(flags); 899 kcpu = this_cpu_ptr(ctx->cpu); 900 if (!kcpu->reqs_available) { 901 int old, avail = atomic_read(&ctx->reqs_available); 902 903 do { 904 if (avail < ctx->req_batch) 905 goto out; 906 907 old = avail; 908 avail = atomic_cmpxchg(&ctx->reqs_available, 909 avail, avail - ctx->req_batch); 910 } while (avail != old); 911 912 kcpu->reqs_available += ctx->req_batch; 913 } 914 915 ret = true; 916 kcpu->reqs_available--; 917out: 918 local_irq_restore(flags); 919 return ret; 920} 921 922/* refill_reqs_available 923 * Updates the reqs_available reference counts used for tracking the 924 * number of free slots in the completion ring. This can be called 925 * from aio_complete() (to optimistically update reqs_available) or 926 * from aio_get_req() (the we're out of events case). It must be 927 * called holding ctx->completion_lock. 928 */ 929static void refill_reqs_available(struct kioctx *ctx, unsigned head, 930 unsigned tail) 931{ 932 unsigned events_in_ring, completed; 933 934 /* Clamp head since userland can write to it. */ 935 head %= ctx->nr_events; 936 if (head <= tail) 937 events_in_ring = tail - head; 938 else 939 events_in_ring = ctx->nr_events - (head - tail); 940 941 completed = ctx->completed_events; 942 if (events_in_ring < completed) 943 completed -= events_in_ring; 944 else 945 completed = 0; 946 947 if (!completed) 948 return; 949 950 ctx->completed_events -= completed; 951 put_reqs_available(ctx, completed); 952} 953 954/* user_refill_reqs_available 955 * Called to refill reqs_available when aio_get_req() encounters an 956 * out of space in the completion ring. 957 */ 958static void user_refill_reqs_available(struct kioctx *ctx) 959{ 960 spin_lock_irq(&ctx->completion_lock); 961 if (ctx->completed_events) { 962 struct aio_ring *ring; 963 unsigned head; 964 965 /* Access of ring->head may race with aio_read_events_ring() 966 * here, but that's okay since whether we read the old version 967 * or the new version, and either will be valid. The important 968 * part is that head cannot pass tail since we prevent 969 * aio_complete() from updating tail by holding 970 * ctx->completion_lock. Even if head is invalid, the check 971 * against ctx->completed_events below will make sure we do the 972 * safe/right thing. 973 */ 974 ring = kmap_atomic(ctx->ring_pages[0]); 975 head = ring->head; 976 kunmap_atomic(ring); 977 978 refill_reqs_available(ctx, head, ctx->tail); 979 } 980 981 spin_unlock_irq(&ctx->completion_lock); 982} 983 984/* aio_get_req 985 * Allocate a slot for an aio request. 986 * Returns NULL if no requests are free. 987 */ 988static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx) 989{ 990 struct aio_kiocb *req; 991 992 if (!get_reqs_available(ctx)) { 993 user_refill_reqs_available(ctx); 994 if (!get_reqs_available(ctx)) 995 return NULL; 996 } 997 998 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO); 999 if (unlikely(!req)) 1000 goto out_put; 1001 1002 percpu_ref_get(&ctx->reqs); 1003 1004 req->ki_ctx = ctx; 1005 return req; 1006out_put: 1007 put_reqs_available(ctx, 1); 1008 return NULL; 1009} 1010 1011static void kiocb_free(struct aio_kiocb *req) 1012{ 1013 if (req->common.ki_filp) 1014 fput(req->common.ki_filp); 1015 if (req->ki_eventfd != NULL) 1016 eventfd_ctx_put(req->ki_eventfd); 1017 kmem_cache_free(kiocb_cachep, req); 1018} 1019 1020static struct kioctx *lookup_ioctx(unsigned long ctx_id) 1021{ 1022 struct aio_ring __user *ring = (void __user *)ctx_id; 1023 struct mm_struct *mm = current->mm; 1024 struct kioctx *ctx, *ret = NULL; 1025 struct kioctx_table *table; 1026 unsigned id; 1027 1028 if (get_user(id, &ring->id)) 1029 return NULL; 1030 1031 rcu_read_lock(); 1032 table = rcu_dereference(mm->ioctx_table); 1033 1034 if (!table || id >= table->nr) 1035 goto out; 1036 1037 ctx = table->table[id]; 1038 if (ctx && ctx->user_id == ctx_id) { 1039 percpu_ref_get(&ctx->users); 1040 ret = ctx; 1041 } 1042out: 1043 rcu_read_unlock(); 1044 return ret; 1045} 1046 1047/* aio_complete 1048 * Called when the io request on the given iocb is complete. 1049 */ 1050static void aio_complete(struct kiocb *kiocb, long res, long res2) 1051{ 1052 struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common); 1053 struct kioctx *ctx = iocb->ki_ctx; 1054 struct aio_ring *ring; 1055 struct io_event *ev_page, *event; 1056 unsigned tail, pos, head; 1057 unsigned long flags; 1058 1059 /* 1060 * Special case handling for sync iocbs: 1061 * - events go directly into the iocb for fast handling 1062 * - the sync task with the iocb in its stack holds the single iocb 1063 * ref, no other paths have a way to get another ref 1064 * - the sync task helpfully left a reference to itself in the iocb 1065 */ 1066 BUG_ON(is_sync_kiocb(kiocb)); 1067 1068 if (iocb->ki_list.next) { 1069 unsigned long flags; 1070 1071 spin_lock_irqsave(&ctx->ctx_lock, flags); 1072 list_del(&iocb->ki_list); 1073 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 1074 } 1075 1076 /* 1077 * Add a completion event to the ring buffer. Must be done holding 1078 * ctx->completion_lock to prevent other code from messing with the tail 1079 * pointer since we might be called from irq context. 1080 */ 1081 spin_lock_irqsave(&ctx->completion_lock, flags); 1082 1083 tail = ctx->tail; 1084 pos = tail + AIO_EVENTS_OFFSET; 1085 1086 if (++tail >= ctx->nr_events) 1087 tail = 0; 1088 1089 ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); 1090 event = ev_page + pos % AIO_EVENTS_PER_PAGE; 1091 1092 event->obj = (u64)(unsigned long)iocb->ki_user_iocb; 1093 event->data = iocb->ki_user_data; 1094 event->res = res; 1095 event->res2 = res2; 1096 1097 kunmap_atomic(ev_page); 1098 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); 1099 1100 pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n", 1101 ctx, tail, iocb, iocb->ki_user_iocb, iocb->ki_user_data, 1102 res, res2); 1103 1104 /* after flagging the request as done, we 1105 * must never even look at it again 1106 */ 1107 smp_wmb(); /* make event visible before updating tail */ 1108 1109 ctx->tail = tail; 1110 1111 ring = kmap_atomic(ctx->ring_pages[0]); 1112 head = ring->head; 1113 ring->tail = tail; 1114 kunmap_atomic(ring); 1115 flush_dcache_page(ctx->ring_pages[0]); 1116 1117 ctx->completed_events++; 1118 if (ctx->completed_events > 1) 1119 refill_reqs_available(ctx, head, tail); 1120 spin_unlock_irqrestore(&ctx->completion_lock, flags); 1121 1122 pr_debug("added to ring %p at [%u]\n", iocb, tail); 1123 1124 /* 1125 * Check if the user asked us to deliver the result through an 1126 * eventfd. The eventfd_signal() function is safe to be called 1127 * from IRQ context. 1128 */ 1129 if (iocb->ki_eventfd != NULL) 1130 eventfd_signal(iocb->ki_eventfd, 1); 1131 1132 /* everything turned out well, dispose of the aiocb. */ 1133 kiocb_free(iocb); 1134 1135 /* 1136 * We have to order our ring_info tail store above and test 1137 * of the wait list below outside the wait lock. This is 1138 * like in wake_up_bit() where clearing a bit has to be 1139 * ordered with the unlocked test. 1140 */ 1141 smp_mb(); 1142 1143 if (waitqueue_active(&ctx->wait)) 1144 wake_up(&ctx->wait); 1145 1146 percpu_ref_put(&ctx->reqs); 1147} 1148 1149/* aio_read_events_ring 1150 * Pull an event off of the ioctx's event ring. Returns the number of 1151 * events fetched 1152 */ 1153static long aio_read_events_ring(struct kioctx *ctx, 1154 struct io_event __user *event, long nr) 1155{ 1156 struct aio_ring *ring; 1157 unsigned head, tail, pos; 1158 long ret = 0; 1159 int copy_ret; 1160 1161 /* 1162 * The mutex can block and wake us up and that will cause 1163 * wait_event_interruptible_hrtimeout() to schedule without sleeping 1164 * and repeat. This should be rare enough that it doesn't cause 1165 * peformance issues. See the comment in read_events() for more detail. 1166 */ 1167 sched_annotate_sleep(); 1168 mutex_lock(&ctx->ring_lock); 1169 1170 /* Access to ->ring_pages here is protected by ctx->ring_lock. */ 1171 ring = kmap_atomic(ctx->ring_pages[0]); 1172 head = ring->head; 1173 tail = ring->tail; 1174 kunmap_atomic(ring); 1175 1176 /* 1177 * Ensure that once we've read the current tail pointer, that 1178 * we also see the events that were stored up to the tail. 1179 */ 1180 smp_rmb(); 1181 1182 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events); 1183 1184 if (head == tail) 1185 goto out; 1186 1187 head %= ctx->nr_events; 1188 tail %= ctx->nr_events; 1189 1190 while (ret < nr) { 1191 long avail; 1192 struct io_event *ev; 1193 struct page *page; 1194 1195 avail = (head <= tail ? tail : ctx->nr_events) - head; 1196 if (head == tail) 1197 break; 1198 1199 avail = min(avail, nr - ret); 1200 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - 1201 ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE)); 1202 1203 pos = head + AIO_EVENTS_OFFSET; 1204 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]; 1205 pos %= AIO_EVENTS_PER_PAGE; 1206 1207 ev = kmap(page); 1208 copy_ret = copy_to_user(event + ret, ev + pos, 1209 sizeof(*ev) * avail); 1210 kunmap(page); 1211 1212 if (unlikely(copy_ret)) { 1213 ret = -EFAULT; 1214 goto out; 1215 } 1216 1217 ret += avail; 1218 head += avail; 1219 head %= ctx->nr_events; 1220 } 1221 1222 ring = kmap_atomic(ctx->ring_pages[0]); 1223 ring->head = head; 1224 kunmap_atomic(ring); 1225 flush_dcache_page(ctx->ring_pages[0]); 1226 1227 pr_debug("%li h%u t%u\n", ret, head, tail); 1228out: 1229 mutex_unlock(&ctx->ring_lock); 1230 1231 return ret; 1232} 1233 1234static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr, 1235 struct io_event __user *event, long *i) 1236{ 1237 long ret = aio_read_events_ring(ctx, event + *i, nr - *i); 1238 1239 if (ret > 0) 1240 *i += ret; 1241 1242 if (unlikely(atomic_read(&ctx->dead))) 1243 ret = -EINVAL; 1244 1245 if (!*i) 1246 *i = ret; 1247 1248 return ret < 0 || *i >= min_nr; 1249} 1250 1251static long read_events(struct kioctx *ctx, long min_nr, long nr, 1252 struct io_event __user *event, 1253 struct timespec __user *timeout) 1254{ 1255 ktime_t until = { .tv64 = KTIME_MAX }; 1256 long ret = 0; 1257 1258 if (timeout) { 1259 struct timespec ts; 1260 1261 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) 1262 return -EFAULT; 1263 1264 until = timespec_to_ktime(ts); 1265 } 1266 1267 /* 1268 * Note that aio_read_events() is being called as the conditional - i.e. 1269 * we're calling it after prepare_to_wait() has set task state to 1270 * TASK_INTERRUPTIBLE. 1271 * 1272 * But aio_read_events() can block, and if it blocks it's going to flip 1273 * the task state back to TASK_RUNNING. 1274 * 1275 * This should be ok, provided it doesn't flip the state back to 1276 * TASK_RUNNING and return 0 too much - that causes us to spin. That 1277 * will only happen if the mutex_lock() call blocks, and we then find 1278 * the ringbuffer empty. So in practice we should be ok, but it's 1279 * something to be aware of when touching this code. 1280 */ 1281 if (until.tv64 == 0) 1282 aio_read_events(ctx, min_nr, nr, event, &ret); 1283 else 1284 wait_event_interruptible_hrtimeout(ctx->wait, 1285 aio_read_events(ctx, min_nr, nr, event, &ret), 1286 until); 1287 1288 if (!ret && signal_pending(current)) 1289 ret = -EINTR; 1290 1291 return ret; 1292} 1293 1294/* sys_io_setup: 1295 * Create an aio_context capable of receiving at least nr_events. 1296 * ctxp must not point to an aio_context that already exists, and 1297 * must be initialized to 0 prior to the call. On successful 1298 * creation of the aio_context, *ctxp is filled in with the resulting 1299 * handle. May fail with -EINVAL if *ctxp is not initialized, 1300 * if the specified nr_events exceeds internal limits. May fail 1301 * with -EAGAIN if the specified nr_events exceeds the user's limit 1302 * of available events. May fail with -ENOMEM if insufficient kernel 1303 * resources are available. May fail with -EFAULT if an invalid 1304 * pointer is passed for ctxp. Will fail with -ENOSYS if not 1305 * implemented. 1306 */ 1307SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp) 1308{ 1309 struct kioctx *ioctx = NULL; 1310 unsigned long ctx; 1311 long ret; 1312 1313 ret = get_user(ctx, ctxp); 1314 if (unlikely(ret)) 1315 goto out; 1316 1317 ret = -EINVAL; 1318 if (unlikely(ctx || nr_events == 0)) { 1319 pr_debug("EINVAL: ctx %lu nr_events %u\n", 1320 ctx, nr_events); 1321 goto out; 1322 } 1323 1324 ioctx = ioctx_alloc(nr_events); 1325 ret = PTR_ERR(ioctx); 1326 if (!IS_ERR(ioctx)) { 1327 ret = put_user(ioctx->user_id, ctxp); 1328 if (ret) 1329 kill_ioctx(current->mm, ioctx, NULL); 1330 percpu_ref_put(&ioctx->users); 1331 } 1332 1333out: 1334 return ret; 1335} 1336 1337/* sys_io_destroy: 1338 * Destroy the aio_context specified. May cancel any outstanding 1339 * AIOs and block on completion. Will fail with -ENOSYS if not 1340 * implemented. May fail with -EINVAL if the context pointed to 1341 * is invalid. 1342 */ 1343SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx) 1344{ 1345 struct kioctx *ioctx = lookup_ioctx(ctx); 1346 if (likely(NULL != ioctx)) { 1347 struct ctx_rq_wait wait; 1348 int ret; 1349 1350 init_completion(&wait.comp); 1351 atomic_set(&wait.count, 1); 1352 1353 /* Pass requests_done to kill_ioctx() where it can be set 1354 * in a thread-safe way. If we try to set it here then we have 1355 * a race condition if two io_destroy() called simultaneously. 1356 */ 1357 ret = kill_ioctx(current->mm, ioctx, &wait); 1358 percpu_ref_put(&ioctx->users); 1359 1360 /* Wait until all IO for the context are done. Otherwise kernel 1361 * keep using user-space buffers even if user thinks the context 1362 * is destroyed. 1363 */ 1364 if (!ret) 1365 wait_for_completion(&wait.comp); 1366 1367 return ret; 1368 } 1369 pr_debug("EINVAL: invalid context id\n"); 1370 return -EINVAL; 1371} 1372 1373typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *); 1374 1375static int aio_setup_vectored_rw(int rw, char __user *buf, size_t len, 1376 struct iovec **iovec, 1377 bool compat, 1378 struct iov_iter *iter) 1379{ 1380#ifdef CONFIG_COMPAT 1381 if (compat) 1382 return compat_import_iovec(rw, 1383 (struct compat_iovec __user *)buf, 1384 len, UIO_FASTIOV, iovec, iter); 1385#endif 1386 return import_iovec(rw, (struct iovec __user *)buf, 1387 len, UIO_FASTIOV, iovec, iter); 1388} 1389 1390/* 1391 * aio_run_iocb: 1392 * Performs the initial checks and io submission. 1393 */ 1394static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode, 1395 char __user *buf, size_t len, bool compat) 1396{ 1397 struct file *file = req->ki_filp; 1398 ssize_t ret; 1399 int rw; 1400 fmode_t mode; 1401 rw_iter_op *iter_op; 1402 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; 1403 struct iov_iter iter; 1404 1405 switch (opcode) { 1406 case IOCB_CMD_PREAD: 1407 case IOCB_CMD_PREADV: 1408 mode = FMODE_READ; 1409 rw = READ; 1410 iter_op = file->f_op->read_iter; 1411 goto rw_common; 1412 1413 case IOCB_CMD_PWRITE: 1414 case IOCB_CMD_PWRITEV: 1415 mode = FMODE_WRITE; 1416 rw = WRITE; 1417 iter_op = file->f_op->write_iter; 1418 goto rw_common; 1419rw_common: 1420 if (unlikely(!(file->f_mode & mode))) 1421 return -EBADF; 1422 1423 if (!iter_op) 1424 return -EINVAL; 1425 1426 if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV) 1427 ret = aio_setup_vectored_rw(rw, buf, len, 1428 &iovec, compat, &iter); 1429 else { 1430 ret = import_single_range(rw, buf, len, iovec, &iter); 1431 iovec = NULL; 1432 } 1433 if (!ret) 1434 ret = rw_verify_area(rw, file, &req->ki_pos, 1435 iov_iter_count(&iter)); 1436 if (ret < 0) { 1437 kfree(iovec); 1438 return ret; 1439 } 1440 1441 len = ret; 1442 1443 if (rw == WRITE) 1444 file_start_write(file); 1445 1446 ret = iter_op(req, &iter); 1447 1448 if (rw == WRITE) 1449 file_end_write(file); 1450 kfree(iovec); 1451 break; 1452 1453 case IOCB_CMD_FDSYNC: 1454 if (!file->f_op->aio_fsync) 1455 return -EINVAL; 1456 1457 ret = file->f_op->aio_fsync(req, 1); 1458 break; 1459 1460 case IOCB_CMD_FSYNC: 1461 if (!file->f_op->aio_fsync) 1462 return -EINVAL; 1463 1464 ret = file->f_op->aio_fsync(req, 0); 1465 break; 1466 1467 default: 1468 pr_debug("EINVAL: no operation provided\n"); 1469 return -EINVAL; 1470 } 1471 1472 if (ret != -EIOCBQUEUED) { 1473 /* 1474 * There's no easy way to restart the syscall since other AIO's 1475 * may be already running. Just fail this IO with EINTR. 1476 */ 1477 if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR || 1478 ret == -ERESTARTNOHAND || 1479 ret == -ERESTART_RESTARTBLOCK)) 1480 ret = -EINTR; 1481 aio_complete(req, ret, 0); 1482 } 1483 1484 return 0; 1485} 1486 1487static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1488 struct iocb *iocb, bool compat) 1489{ 1490 struct aio_kiocb *req; 1491 ssize_t ret; 1492 1493 /* enforce forwards compatibility on users */ 1494 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) { 1495 pr_debug("EINVAL: reserve field set\n"); 1496 return -EINVAL; 1497 } 1498 1499 /* prevent overflows */ 1500 if (unlikely( 1501 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1502 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1503 ((ssize_t)iocb->aio_nbytes < 0) 1504 )) { 1505 pr_debug("EINVAL: overflow check\n"); 1506 return -EINVAL; 1507 } 1508 1509 req = aio_get_req(ctx); 1510 if (unlikely(!req)) 1511 return -EAGAIN; 1512 1513 req->common.ki_filp = fget(iocb->aio_fildes); 1514 if (unlikely(!req->common.ki_filp)) { 1515 ret = -EBADF; 1516 goto out_put_req; 1517 } 1518 req->common.ki_pos = iocb->aio_offset; 1519 req->common.ki_complete = aio_complete; 1520 req->common.ki_flags = iocb_flags(req->common.ki_filp); 1521 1522 if (iocb->aio_flags & IOCB_FLAG_RESFD) { 1523 /* 1524 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an 1525 * instance of the file* now. The file descriptor must be 1526 * an eventfd() fd, and will be signaled for each completed 1527 * event using the eventfd_signal() function. 1528 */ 1529 req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd); 1530 if (IS_ERR(req->ki_eventfd)) { 1531 ret = PTR_ERR(req->ki_eventfd); 1532 req->ki_eventfd = NULL; 1533 goto out_put_req; 1534 } 1535 1536 req->common.ki_flags |= IOCB_EVENTFD; 1537 } 1538 1539 ret = put_user(KIOCB_KEY, &user_iocb->aio_key); 1540 if (unlikely(ret)) { 1541 pr_debug("EFAULT: aio_key\n"); 1542 goto out_put_req; 1543 } 1544 1545 req->ki_user_iocb = user_iocb; 1546 req->ki_user_data = iocb->aio_data; 1547 1548 ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode, 1549 (char __user *)(unsigned long)iocb->aio_buf, 1550 iocb->aio_nbytes, 1551 compat); 1552 if (ret) 1553 goto out_put_req; 1554 1555 return 0; 1556out_put_req: 1557 put_reqs_available(ctx, 1); 1558 percpu_ref_put(&ctx->reqs); 1559 kiocb_free(req); 1560 return ret; 1561} 1562 1563long do_io_submit(aio_context_t ctx_id, long nr, 1564 struct iocb __user *__user *iocbpp, bool compat) 1565{ 1566 struct kioctx *ctx; 1567 long ret = 0; 1568 int i = 0; 1569 struct blk_plug plug; 1570 1571 if (unlikely(nr < 0)) 1572 return -EINVAL; 1573 1574 if (unlikely(nr > LONG_MAX/sizeof(*iocbpp))) 1575 nr = LONG_MAX/sizeof(*iocbpp); 1576 1577 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1578 return -EFAULT; 1579 1580 ctx = lookup_ioctx(ctx_id); 1581 if (unlikely(!ctx)) { 1582 pr_debug("EINVAL: invalid context id\n"); 1583 return -EINVAL; 1584 } 1585 1586 blk_start_plug(&plug); 1587 1588 /* 1589 * AKPM: should this return a partial result if some of the IOs were 1590 * successfully submitted? 1591 */ 1592 for (i=0; i<nr; i++) { 1593 struct iocb __user *user_iocb; 1594 struct iocb tmp; 1595 1596 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1597 ret = -EFAULT; 1598 break; 1599 } 1600 1601 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1602 ret = -EFAULT; 1603 break; 1604 } 1605 1606 ret = io_submit_one(ctx, user_iocb, &tmp, compat); 1607 if (ret) 1608 break; 1609 } 1610 blk_finish_plug(&plug); 1611 1612 percpu_ref_put(&ctx->users); 1613 return i ? i : ret; 1614} 1615 1616/* sys_io_submit: 1617 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1618 * the number of iocbs queued. May return -EINVAL if the aio_context 1619 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1620 * *iocbpp[0] is not properly initialized, if the operation specified 1621 * is invalid for the file descriptor in the iocb. May fail with 1622 * -EFAULT if any of the data structures point to invalid data. May 1623 * fail with -EBADF if the file descriptor specified in the first 1624 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1625 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1626 * fail with -ENOSYS if not implemented. 1627 */ 1628SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, 1629 struct iocb __user * __user *, iocbpp) 1630{ 1631 return do_io_submit(ctx_id, nr, iocbpp, 0); 1632} 1633 1634/* lookup_kiocb 1635 * Finds a given iocb for cancellation. 1636 */ 1637static struct aio_kiocb * 1638lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key) 1639{ 1640 struct aio_kiocb *kiocb; 1641 1642 assert_spin_locked(&ctx->ctx_lock); 1643 1644 if (key != KIOCB_KEY) 1645 return NULL; 1646 1647 /* TODO: use a hash or array, this sucks. */ 1648 list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) { 1649 if (kiocb->ki_user_iocb == iocb) 1650 return kiocb; 1651 } 1652 return NULL; 1653} 1654 1655/* sys_io_cancel: 1656 * Attempts to cancel an iocb previously passed to io_submit. If 1657 * the operation is successfully cancelled, the resulting event is 1658 * copied into the memory pointed to by result without being placed 1659 * into the completion queue and 0 is returned. May fail with 1660 * -EFAULT if any of the data structures pointed to are invalid. 1661 * May fail with -EINVAL if aio_context specified by ctx_id is 1662 * invalid. May fail with -EAGAIN if the iocb specified was not 1663 * cancelled. Will fail with -ENOSYS if not implemented. 1664 */ 1665SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, 1666 struct io_event __user *, result) 1667{ 1668 struct kioctx *ctx; 1669 struct aio_kiocb *kiocb; 1670 u32 key; 1671 int ret; 1672 1673 ret = get_user(key, &iocb->aio_key); 1674 if (unlikely(ret)) 1675 return -EFAULT; 1676 1677 ctx = lookup_ioctx(ctx_id); 1678 if (unlikely(!ctx)) 1679 return -EINVAL; 1680 1681 spin_lock_irq(&ctx->ctx_lock); 1682 1683 kiocb = lookup_kiocb(ctx, iocb, key); 1684 if (kiocb) 1685 ret = kiocb_cancel(kiocb); 1686 else 1687 ret = -EINVAL; 1688 1689 spin_unlock_irq(&ctx->ctx_lock); 1690 1691 if (!ret) { 1692 /* 1693 * The result argument is no longer used - the io_event is 1694 * always delivered via the ring buffer. -EINPROGRESS indicates 1695 * cancellation is progress: 1696 */ 1697 ret = -EINPROGRESS; 1698 } 1699 1700 percpu_ref_put(&ctx->users); 1701 1702 return ret; 1703} 1704 1705/* io_getevents: 1706 * Attempts to read at least min_nr events and up to nr events from 1707 * the completion queue for the aio_context specified by ctx_id. If 1708 * it succeeds, the number of read events is returned. May fail with 1709 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is 1710 * out of range, if timeout is out of range. May fail with -EFAULT 1711 * if any of the memory specified is invalid. May return 0 or 1712 * < min_nr if the timeout specified by timeout has elapsed 1713 * before sufficient events are available, where timeout == NULL 1714 * specifies an infinite timeout. Note that the timeout pointed to by 1715 * timeout is relative. Will fail with -ENOSYS if not implemented. 1716 */ 1717SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, 1718 long, min_nr, 1719 long, nr, 1720 struct io_event __user *, events, 1721 struct timespec __user *, timeout) 1722{ 1723 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1724 long ret = -EINVAL; 1725 1726 if (likely(ioctx)) { 1727 if (likely(min_nr <= nr && min_nr >= 0)) 1728 ret = read_events(ioctx, min_nr, nr, events, timeout); 1729 percpu_ref_put(&ioctx->users); 1730 } 1731 return ret; 1732} 1733