1 /* 2 * An async IO implementation for Linux 3 * Written by Benjamin LaHaise <bcrl@kvack.org> 4 * 5 * Implements an efficient asynchronous io interface. 6 * 7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved. 8 * 9 * See ../COPYING for licensing terms. 10 */ 11 #include <linux/kernel.h> 12 #include <linux/init.h> 13 #include <linux/errno.h> 14 #include <linux/time.h> 15 #include <linux/aio_abi.h> 16 #include <linux/module.h> 17 #include <linux/syscalls.h> 18 #include <linux/uio.h> 19 20 #define DEBUG 0 21 22 #include <linux/sched.h> 23 #include <linux/fs.h> 24 #include <linux/file.h> 25 #include <linux/mm.h> 26 #include <linux/mman.h> 27 #include <linux/slab.h> 28 #include <linux/timer.h> 29 #include <linux/aio.h> 30 #include <linux/highmem.h> 31 #include <linux/workqueue.h> 32 #include <linux/security.h> 33 #include <linux/eventfd.h> 34 35 #include <asm/kmap_types.h> 36 #include <asm/uaccess.h> 37 #include <asm/mmu_context.h> 38 39 #if DEBUG > 1 40 #define dprintk printk 41 #else 42 #define dprintk(x...) do { ; } while (0) 43 #endif 44 45 /*------ sysctl variables----*/ 46 static DEFINE_SPINLOCK(aio_nr_lock); 47 unsigned long aio_nr; /* current system wide number of aio requests */ 48 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ 49 /*----end sysctl variables---*/ 50 51 static struct kmem_cache *kiocb_cachep; 52 static struct kmem_cache *kioctx_cachep; 53 54 static struct workqueue_struct *aio_wq; 55 56 /* Used for rare fput completion. */ 57 static void aio_fput_routine(struct work_struct *); 58 static DECLARE_WORK(fput_work, aio_fput_routine); 59 60 static DEFINE_SPINLOCK(fput_lock); 61 static LIST_HEAD(fput_head); 62 63 static void aio_kick_handler(struct work_struct *); 64 static void aio_queue_work(struct kioctx *); 65 66 /* aio_setup 67 * Creates the slab caches used by the aio routines, panic on 68 * failure as this is done early during the boot sequence. 69 */ 70 static int __init aio_setup(void) 71 { 72 kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); 73 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); 74 75 aio_wq = create_workqueue("aio"); 76 77 pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page)); 78 79 return 0; 80 } 81 82 static void aio_free_ring(struct kioctx *ctx) 83 { 84 struct aio_ring_info *info = &ctx->ring_info; 85 long i; 86 87 for (i=0; i<info->nr_pages; i++) 88 put_page(info->ring_pages[i]); 89 90 if (info->mmap_size) { 91 down_write(&ctx->mm->mmap_sem); 92 do_munmap(ctx->mm, info->mmap_base, info->mmap_size); 93 up_write(&ctx->mm->mmap_sem); 94 } 95 96 if (info->ring_pages && info->ring_pages != info->internal_pages) 97 kfree(info->ring_pages); 98 info->ring_pages = NULL; 99 info->nr = 0; 100 } 101 102 static int aio_setup_ring(struct kioctx *ctx) 103 { 104 struct aio_ring *ring; 105 struct aio_ring_info *info = &ctx->ring_info; 106 unsigned nr_events = ctx->max_reqs; 107 unsigned long size; 108 int nr_pages; 109 110 /* Compensate for the ring buffer's head/tail overlap entry */ 111 nr_events += 2; /* 1 is required, 2 for good luck */ 112 113 size = sizeof(struct aio_ring); 114 size += sizeof(struct io_event) * nr_events; 115 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; 116 117 if (nr_pages < 0) 118 return -EINVAL; 119 120 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); 121 122 info->nr = 0; 123 info->ring_pages = info->internal_pages; 124 if (nr_pages > AIO_RING_PAGES) { 125 info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL); 126 if (!info->ring_pages) 127 return -ENOMEM; 128 } 129 130 info->mmap_size = nr_pages * PAGE_SIZE; 131 dprintk("attempting mmap of %lu bytes\n", info->mmap_size); 132 down_write(&ctx->mm->mmap_sem); 133 info->mmap_base = do_mmap(NULL, 0, info->mmap_size, 134 PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, 135 0); 136 if (IS_ERR((void *)info->mmap_base)) { 137 up_write(&ctx->mm->mmap_sem); 138 info->mmap_size = 0; 139 aio_free_ring(ctx); 140 return -EAGAIN; 141 } 142 143 dprintk("mmap address: 0x%08lx\n", info->mmap_base); 144 info->nr_pages = get_user_pages(current, ctx->mm, 145 info->mmap_base, nr_pages, 146 1, 0, info->ring_pages, NULL); 147 up_write(&ctx->mm->mmap_sem); 148 149 if (unlikely(info->nr_pages != nr_pages)) { 150 aio_free_ring(ctx); 151 return -EAGAIN; 152 } 153 154 ctx->user_id = info->mmap_base; 155 156 info->nr = nr_events; /* trusted copy */ 157 158 ring = kmap_atomic(info->ring_pages[0], KM_USER0); 159 ring->nr = nr_events; /* user copy */ 160 ring->id = ctx->user_id; 161 ring->head = ring->tail = 0; 162 ring->magic = AIO_RING_MAGIC; 163 ring->compat_features = AIO_RING_COMPAT_FEATURES; 164 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; 165 ring->header_length = sizeof(struct aio_ring); 166 kunmap_atomic(ring, KM_USER0); 167 168 return 0; 169 } 170 171 172 /* aio_ring_event: returns a pointer to the event at the given index from 173 * kmap_atomic(, km). Release the pointer with put_aio_ring_event(); 174 */ 175 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) 176 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) 177 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) 178 179 #define aio_ring_event(info, nr, km) ({ \ 180 unsigned pos = (nr) + AIO_EVENTS_OFFSET; \ 181 struct io_event *__event; \ 182 __event = kmap_atomic( \ 183 (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \ 184 __event += pos % AIO_EVENTS_PER_PAGE; \ 185 __event; \ 186 }) 187 188 #define put_aio_ring_event(event, km) do { \ 189 struct io_event *__event = (event); \ 190 (void)__event; \ 191 kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \ 192 } while(0) 193 194 /* ioctx_alloc 195 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. 196 */ 197 static struct kioctx *ioctx_alloc(unsigned nr_events) 198 { 199 struct mm_struct *mm; 200 struct kioctx *ctx; 201 202 /* Prevent overflows */ 203 if ((nr_events > (0x10000000U / sizeof(struct io_event))) || 204 (nr_events > (0x10000000U / sizeof(struct kiocb)))) { 205 pr_debug("ENOMEM: nr_events too high\n"); 206 return ERR_PTR(-EINVAL); 207 } 208 209 if ((unsigned long)nr_events > aio_max_nr) 210 return ERR_PTR(-EAGAIN); 211 212 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); 213 if (!ctx) 214 return ERR_PTR(-ENOMEM); 215 216 ctx->max_reqs = nr_events; 217 mm = ctx->mm = current->mm; 218 atomic_inc(&mm->mm_count); 219 220 atomic_set(&ctx->users, 1); 221 spin_lock_init(&ctx->ctx_lock); 222 spin_lock_init(&ctx->ring_info.ring_lock); 223 init_waitqueue_head(&ctx->wait); 224 225 INIT_LIST_HEAD(&ctx->active_reqs); 226 INIT_LIST_HEAD(&ctx->run_list); 227 INIT_DELAYED_WORK(&ctx->wq, aio_kick_handler); 228 229 if (aio_setup_ring(ctx) < 0) 230 goto out_freectx; 231 232 /* limit the number of system wide aios */ 233 spin_lock(&aio_nr_lock); 234 if (aio_nr + ctx->max_reqs > aio_max_nr || 235 aio_nr + ctx->max_reqs < aio_nr) 236 ctx->max_reqs = 0; 237 else 238 aio_nr += ctx->max_reqs; 239 spin_unlock(&aio_nr_lock); 240 if (ctx->max_reqs == 0) 241 goto out_cleanup; 242 243 /* now link into global list. kludge. FIXME */ 244 write_lock(&mm->ioctx_list_lock); 245 ctx->next = mm->ioctx_list; 246 mm->ioctx_list = ctx; 247 write_unlock(&mm->ioctx_list_lock); 248 249 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", 250 ctx, ctx->user_id, current->mm, ctx->ring_info.nr); 251 return ctx; 252 253 out_cleanup: 254 __put_ioctx(ctx); 255 return ERR_PTR(-EAGAIN); 256 257 out_freectx: 258 mmdrop(mm); 259 kmem_cache_free(kioctx_cachep, ctx); 260 ctx = ERR_PTR(-ENOMEM); 261 262 dprintk("aio: error allocating ioctx %p\n", ctx); 263 return ctx; 264 } 265 266 /* aio_cancel_all 267 * Cancels all outstanding aio requests on an aio context. Used 268 * when the processes owning a context have all exited to encourage 269 * the rapid destruction of the kioctx. 270 */ 271 static void aio_cancel_all(struct kioctx *ctx) 272 { 273 int (*cancel)(struct kiocb *, struct io_event *); 274 struct io_event res; 275 spin_lock_irq(&ctx->ctx_lock); 276 ctx->dead = 1; 277 while (!list_empty(&ctx->active_reqs)) { 278 struct list_head *pos = ctx->active_reqs.next; 279 struct kiocb *iocb = list_kiocb(pos); 280 list_del_init(&iocb->ki_list); 281 cancel = iocb->ki_cancel; 282 kiocbSetCancelled(iocb); 283 if (cancel) { 284 iocb->ki_users++; 285 spin_unlock_irq(&ctx->ctx_lock); 286 cancel(iocb, &res); 287 spin_lock_irq(&ctx->ctx_lock); 288 } 289 } 290 spin_unlock_irq(&ctx->ctx_lock); 291 } 292 293 static void wait_for_all_aios(struct kioctx *ctx) 294 { 295 struct task_struct *tsk = current; 296 DECLARE_WAITQUEUE(wait, tsk); 297 298 spin_lock_irq(&ctx->ctx_lock); 299 if (!ctx->reqs_active) 300 goto out; 301 302 add_wait_queue(&ctx->wait, &wait); 303 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 304 while (ctx->reqs_active) { 305 spin_unlock_irq(&ctx->ctx_lock); 306 io_schedule(); 307 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 308 spin_lock_irq(&ctx->ctx_lock); 309 } 310 __set_task_state(tsk, TASK_RUNNING); 311 remove_wait_queue(&ctx->wait, &wait); 312 313 out: 314 spin_unlock_irq(&ctx->ctx_lock); 315 } 316 317 /* wait_on_sync_kiocb: 318 * Waits on the given sync kiocb to complete. 319 */ 320 ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb) 321 { 322 while (iocb->ki_users) { 323 set_current_state(TASK_UNINTERRUPTIBLE); 324 if (!iocb->ki_users) 325 break; 326 io_schedule(); 327 } 328 __set_current_state(TASK_RUNNING); 329 return iocb->ki_user_data; 330 } 331 332 /* exit_aio: called when the last user of mm goes away. At this point, 333 * there is no way for any new requests to be submited or any of the 334 * io_* syscalls to be called on the context. However, there may be 335 * outstanding requests which hold references to the context; as they 336 * go away, they will call put_ioctx and release any pinned memory 337 * associated with the request (held via struct page * references). 338 */ 339 void fastcall exit_aio(struct mm_struct *mm) 340 { 341 struct kioctx *ctx = mm->ioctx_list; 342 mm->ioctx_list = NULL; 343 while (ctx) { 344 struct kioctx *next = ctx->next; 345 ctx->next = NULL; 346 aio_cancel_all(ctx); 347 348 wait_for_all_aios(ctx); 349 /* 350 * Ensure we don't leave the ctx on the aio_wq 351 */ 352 cancel_work_sync(&ctx->wq.work); 353 354 if (1 != atomic_read(&ctx->users)) 355 printk(KERN_DEBUG 356 "exit_aio:ioctx still alive: %d %d %d\n", 357 atomic_read(&ctx->users), ctx->dead, 358 ctx->reqs_active); 359 put_ioctx(ctx); 360 ctx = next; 361 } 362 } 363 364 /* __put_ioctx 365 * Called when the last user of an aio context has gone away, 366 * and the struct needs to be freed. 367 */ 368 void fastcall __put_ioctx(struct kioctx *ctx) 369 { 370 unsigned nr_events = ctx->max_reqs; 371 372 BUG_ON(ctx->reqs_active); 373 374 cancel_delayed_work(&ctx->wq); 375 cancel_work_sync(&ctx->wq.work); 376 aio_free_ring(ctx); 377 mmdrop(ctx->mm); 378 ctx->mm = NULL; 379 pr_debug("__put_ioctx: freeing %p\n", ctx); 380 kmem_cache_free(kioctx_cachep, ctx); 381 382 if (nr_events) { 383 spin_lock(&aio_nr_lock); 384 BUG_ON(aio_nr - nr_events > aio_nr); 385 aio_nr -= nr_events; 386 spin_unlock(&aio_nr_lock); 387 } 388 } 389 390 /* aio_get_req 391 * Allocate a slot for an aio request. Increments the users count 392 * of the kioctx so that the kioctx stays around until all requests are 393 * complete. Returns NULL if no requests are free. 394 * 395 * Returns with kiocb->users set to 2. The io submit code path holds 396 * an extra reference while submitting the i/o. 397 * This prevents races between the aio code path referencing the 398 * req (after submitting it) and aio_complete() freeing the req. 399 */ 400 static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx)); 401 static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx) 402 { 403 struct kiocb *req = NULL; 404 struct aio_ring *ring; 405 int okay = 0; 406 407 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); 408 if (unlikely(!req)) 409 return NULL; 410 411 req->ki_flags = 0; 412 req->ki_users = 2; 413 req->ki_key = 0; 414 req->ki_ctx = ctx; 415 req->ki_cancel = NULL; 416 req->ki_retry = NULL; 417 req->ki_dtor = NULL; 418 req->private = NULL; 419 req->ki_iovec = NULL; 420 INIT_LIST_HEAD(&req->ki_run_list); 421 req->ki_eventfd = ERR_PTR(-EINVAL); 422 423 /* Check if the completion queue has enough free space to 424 * accept an event from this io. 425 */ 426 spin_lock_irq(&ctx->ctx_lock); 427 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); 428 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { 429 list_add(&req->ki_list, &ctx->active_reqs); 430 ctx->reqs_active++; 431 okay = 1; 432 } 433 kunmap_atomic(ring, KM_USER0); 434 spin_unlock_irq(&ctx->ctx_lock); 435 436 if (!okay) { 437 kmem_cache_free(kiocb_cachep, req); 438 req = NULL; 439 } 440 441 return req; 442 } 443 444 static inline struct kiocb *aio_get_req(struct kioctx *ctx) 445 { 446 struct kiocb *req; 447 /* Handle a potential starvation case -- should be exceedingly rare as 448 * requests will be stuck on fput_head only if the aio_fput_routine is 449 * delayed and the requests were the last user of the struct file. 450 */ 451 req = __aio_get_req(ctx); 452 if (unlikely(NULL == req)) { 453 aio_fput_routine(NULL); 454 req = __aio_get_req(ctx); 455 } 456 return req; 457 } 458 459 static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) 460 { 461 assert_spin_locked(&ctx->ctx_lock); 462 463 if (!IS_ERR(req->ki_eventfd)) 464 fput(req->ki_eventfd); 465 if (req->ki_dtor) 466 req->ki_dtor(req); 467 if (req->ki_iovec != &req->ki_inline_vec) 468 kfree(req->ki_iovec); 469 kmem_cache_free(kiocb_cachep, req); 470 ctx->reqs_active--; 471 472 if (unlikely(!ctx->reqs_active && ctx->dead)) 473 wake_up(&ctx->wait); 474 } 475 476 static void aio_fput_routine(struct work_struct *data) 477 { 478 spin_lock_irq(&fput_lock); 479 while (likely(!list_empty(&fput_head))) { 480 struct kiocb *req = list_kiocb(fput_head.next); 481 struct kioctx *ctx = req->ki_ctx; 482 483 list_del(&req->ki_list); 484 spin_unlock_irq(&fput_lock); 485 486 /* Complete the fput */ 487 __fput(req->ki_filp); 488 489 /* Link the iocb into the context's free list */ 490 spin_lock_irq(&ctx->ctx_lock); 491 really_put_req(ctx, req); 492 spin_unlock_irq(&ctx->ctx_lock); 493 494 put_ioctx(ctx); 495 spin_lock_irq(&fput_lock); 496 } 497 spin_unlock_irq(&fput_lock); 498 } 499 500 /* __aio_put_req 501 * Returns true if this put was the last user of the request. 502 */ 503 static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) 504 { 505 dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n", 506 req, atomic_read(&req->ki_filp->f_count)); 507 508 assert_spin_locked(&ctx->ctx_lock); 509 510 req->ki_users --; 511 BUG_ON(req->ki_users < 0); 512 if (likely(req->ki_users)) 513 return 0; 514 list_del(&req->ki_list); /* remove from active_reqs */ 515 req->ki_cancel = NULL; 516 req->ki_retry = NULL; 517 518 /* Must be done under the lock to serialise against cancellation. 519 * Call this aio_fput as it duplicates fput via the fput_work. 520 */ 521 if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) { 522 get_ioctx(ctx); 523 spin_lock(&fput_lock); 524 list_add(&req->ki_list, &fput_head); 525 spin_unlock(&fput_lock); 526 queue_work(aio_wq, &fput_work); 527 } else 528 really_put_req(ctx, req); 529 return 1; 530 } 531 532 /* aio_put_req 533 * Returns true if this put was the last user of the kiocb, 534 * false if the request is still in use. 535 */ 536 int fastcall aio_put_req(struct kiocb *req) 537 { 538 struct kioctx *ctx = req->ki_ctx; 539 int ret; 540 spin_lock_irq(&ctx->ctx_lock); 541 ret = __aio_put_req(ctx, req); 542 spin_unlock_irq(&ctx->ctx_lock); 543 return ret; 544 } 545 546 /* Lookup an ioctx id. ioctx_list is lockless for reads. 547 * FIXME: this is O(n) and is only suitable for development. 548 */ 549 struct kioctx *lookup_ioctx(unsigned long ctx_id) 550 { 551 struct kioctx *ioctx; 552 struct mm_struct *mm; 553 554 mm = current->mm; 555 read_lock(&mm->ioctx_list_lock); 556 for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next) 557 if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) { 558 get_ioctx(ioctx); 559 break; 560 } 561 read_unlock(&mm->ioctx_list_lock); 562 563 return ioctx; 564 } 565 566 /* 567 * use_mm 568 * Makes the calling kernel thread take on the specified 569 * mm context. 570 * Called by the retry thread execute retries within the 571 * iocb issuer's mm context, so that copy_from/to_user 572 * operations work seamlessly for aio. 573 * (Note: this routine is intended to be called only 574 * from a kernel thread context) 575 */ 576 static void use_mm(struct mm_struct *mm) 577 { 578 struct mm_struct *active_mm; 579 struct task_struct *tsk = current; 580 581 task_lock(tsk); 582 tsk->flags |= PF_BORROWED_MM; 583 active_mm = tsk->active_mm; 584 atomic_inc(&mm->mm_count); 585 tsk->mm = mm; 586 tsk->active_mm = mm; 587 /* 588 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise 589 * it won't work. Update it accordingly if you change it here 590 */ 591 switch_mm(active_mm, mm, tsk); 592 task_unlock(tsk); 593 594 mmdrop(active_mm); 595 } 596 597 /* 598 * unuse_mm 599 * Reverses the effect of use_mm, i.e. releases the 600 * specified mm context which was earlier taken on 601 * by the calling kernel thread 602 * (Note: this routine is intended to be called only 603 * from a kernel thread context) 604 */ 605 static void unuse_mm(struct mm_struct *mm) 606 { 607 struct task_struct *tsk = current; 608 609 task_lock(tsk); 610 tsk->flags &= ~PF_BORROWED_MM; 611 tsk->mm = NULL; 612 /* active_mm is still 'mm' */ 613 enter_lazy_tlb(mm, tsk); 614 task_unlock(tsk); 615 } 616 617 /* 618 * Queue up a kiocb to be retried. Assumes that the kiocb 619 * has already been marked as kicked, and places it on 620 * the retry run list for the corresponding ioctx, if it 621 * isn't already queued. Returns 1 if it actually queued 622 * the kiocb (to tell the caller to activate the work 623 * queue to process it), or 0, if it found that it was 624 * already queued. 625 */ 626 static inline int __queue_kicked_iocb(struct kiocb *iocb) 627 { 628 struct kioctx *ctx = iocb->ki_ctx; 629 630 assert_spin_locked(&ctx->ctx_lock); 631 632 if (list_empty(&iocb->ki_run_list)) { 633 list_add_tail(&iocb->ki_run_list, 634 &ctx->run_list); 635 return 1; 636 } 637 return 0; 638 } 639 640 /* aio_run_iocb 641 * This is the core aio execution routine. It is 642 * invoked both for initial i/o submission and 643 * subsequent retries via the aio_kick_handler. 644 * Expects to be invoked with iocb->ki_ctx->lock 645 * already held. The lock is released and reacquired 646 * as needed during processing. 647 * 648 * Calls the iocb retry method (already setup for the 649 * iocb on initial submission) for operation specific 650 * handling, but takes care of most of common retry 651 * execution details for a given iocb. The retry method 652 * needs to be non-blocking as far as possible, to avoid 653 * holding up other iocbs waiting to be serviced by the 654 * retry kernel thread. 655 * 656 * The trickier parts in this code have to do with 657 * ensuring that only one retry instance is in progress 658 * for a given iocb at any time. Providing that guarantee 659 * simplifies the coding of individual aio operations as 660 * it avoids various potential races. 661 */ 662 static ssize_t aio_run_iocb(struct kiocb *iocb) 663 { 664 struct kioctx *ctx = iocb->ki_ctx; 665 ssize_t (*retry)(struct kiocb *); 666 ssize_t ret; 667 668 if (!(retry = iocb->ki_retry)) { 669 printk("aio_run_iocb: iocb->ki_retry = NULL\n"); 670 return 0; 671 } 672 673 /* 674 * We don't want the next retry iteration for this 675 * operation to start until this one has returned and 676 * updated the iocb state. However, wait_queue functions 677 * can trigger a kick_iocb from interrupt context in the 678 * meantime, indicating that data is available for the next 679 * iteration. We want to remember that and enable the 680 * next retry iteration _after_ we are through with 681 * this one. 682 * 683 * So, in order to be able to register a "kick", but 684 * prevent it from being queued now, we clear the kick 685 * flag, but make the kick code *think* that the iocb is 686 * still on the run list until we are actually done. 687 * When we are done with this iteration, we check if 688 * the iocb was kicked in the meantime and if so, queue 689 * it up afresh. 690 */ 691 692 kiocbClearKicked(iocb); 693 694 /* 695 * This is so that aio_complete knows it doesn't need to 696 * pull the iocb off the run list (We can't just call 697 * INIT_LIST_HEAD because we don't want a kick_iocb to 698 * queue this on the run list yet) 699 */ 700 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; 701 spin_unlock_irq(&ctx->ctx_lock); 702 703 /* Quit retrying if the i/o has been cancelled */ 704 if (kiocbIsCancelled(iocb)) { 705 ret = -EINTR; 706 aio_complete(iocb, ret, 0); 707 /* must not access the iocb after this */ 708 goto out; 709 } 710 711 /* 712 * Now we are all set to call the retry method in async 713 * context. 714 */ 715 ret = retry(iocb); 716 717 if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) { 718 BUG_ON(!list_empty(&iocb->ki_wait.task_list)); 719 aio_complete(iocb, ret, 0); 720 } 721 out: 722 spin_lock_irq(&ctx->ctx_lock); 723 724 if (-EIOCBRETRY == ret) { 725 /* 726 * OK, now that we are done with this iteration 727 * and know that there is more left to go, 728 * this is where we let go so that a subsequent 729 * "kick" can start the next iteration 730 */ 731 732 /* will make __queue_kicked_iocb succeed from here on */ 733 INIT_LIST_HEAD(&iocb->ki_run_list); 734 /* we must queue the next iteration ourselves, if it 735 * has already been kicked */ 736 if (kiocbIsKicked(iocb)) { 737 __queue_kicked_iocb(iocb); 738 739 /* 740 * __queue_kicked_iocb will always return 1 here, because 741 * iocb->ki_run_list is empty at this point so it should 742 * be safe to unconditionally queue the context into the 743 * work queue. 744 */ 745 aio_queue_work(ctx); 746 } 747 } 748 return ret; 749 } 750 751 /* 752 * __aio_run_iocbs: 753 * Process all pending retries queued on the ioctx 754 * run list. 755 * Assumes it is operating within the aio issuer's mm 756 * context. 757 */ 758 static int __aio_run_iocbs(struct kioctx *ctx) 759 { 760 struct kiocb *iocb; 761 struct list_head run_list; 762 763 assert_spin_locked(&ctx->ctx_lock); 764 765 list_replace_init(&ctx->run_list, &run_list); 766 while (!list_empty(&run_list)) { 767 iocb = list_entry(run_list.next, struct kiocb, 768 ki_run_list); 769 list_del(&iocb->ki_run_list); 770 /* 771 * Hold an extra reference while retrying i/o. 772 */ 773 iocb->ki_users++; /* grab extra reference */ 774 aio_run_iocb(iocb); 775 __aio_put_req(ctx, iocb); 776 } 777 if (!list_empty(&ctx->run_list)) 778 return 1; 779 return 0; 780 } 781 782 static void aio_queue_work(struct kioctx * ctx) 783 { 784 unsigned long timeout; 785 /* 786 * if someone is waiting, get the work started right 787 * away, otherwise, use a longer delay 788 */ 789 smp_mb(); 790 if (waitqueue_active(&ctx->wait)) 791 timeout = 1; 792 else 793 timeout = HZ/10; 794 queue_delayed_work(aio_wq, &ctx->wq, timeout); 795 } 796 797 798 /* 799 * aio_run_iocbs: 800 * Process all pending retries queued on the ioctx 801 * run list. 802 * Assumes it is operating within the aio issuer's mm 803 * context. 804 */ 805 static inline void aio_run_iocbs(struct kioctx *ctx) 806 { 807 int requeue; 808 809 spin_lock_irq(&ctx->ctx_lock); 810 811 requeue = __aio_run_iocbs(ctx); 812 spin_unlock_irq(&ctx->ctx_lock); 813 if (requeue) 814 aio_queue_work(ctx); 815 } 816 817 /* 818 * just like aio_run_iocbs, but keeps running them until 819 * the list stays empty 820 */ 821 static inline void aio_run_all_iocbs(struct kioctx *ctx) 822 { 823 spin_lock_irq(&ctx->ctx_lock); 824 while (__aio_run_iocbs(ctx)) 825 ; 826 spin_unlock_irq(&ctx->ctx_lock); 827 } 828 829 /* 830 * aio_kick_handler: 831 * Work queue handler triggered to process pending 832 * retries on an ioctx. Takes on the aio issuer's 833 * mm context before running the iocbs, so that 834 * copy_xxx_user operates on the issuer's address 835 * space. 836 * Run on aiod's context. 837 */ 838 static void aio_kick_handler(struct work_struct *work) 839 { 840 struct kioctx *ctx = container_of(work, struct kioctx, wq.work); 841 mm_segment_t oldfs = get_fs(); 842 struct mm_struct *mm; 843 int requeue; 844 845 set_fs(USER_DS); 846 use_mm(ctx->mm); 847 spin_lock_irq(&ctx->ctx_lock); 848 requeue =__aio_run_iocbs(ctx); 849 mm = ctx->mm; 850 spin_unlock_irq(&ctx->ctx_lock); 851 unuse_mm(mm); 852 set_fs(oldfs); 853 /* 854 * we're in a worker thread already, don't use queue_delayed_work, 855 */ 856 if (requeue) 857 queue_delayed_work(aio_wq, &ctx->wq, 0); 858 } 859 860 861 /* 862 * Called by kick_iocb to queue the kiocb for retry 863 * and if required activate the aio work queue to process 864 * it 865 */ 866 static void try_queue_kicked_iocb(struct kiocb *iocb) 867 { 868 struct kioctx *ctx = iocb->ki_ctx; 869 unsigned long flags; 870 int run = 0; 871 872 /* We're supposed to be the only path putting the iocb back on the run 873 * list. If we find that the iocb is *back* on a wait queue already 874 * than retry has happened before we could queue the iocb. This also 875 * means that the retry could have completed and freed our iocb, no 876 * good. */ 877 BUG_ON((!list_empty(&iocb->ki_wait.task_list))); 878 879 spin_lock_irqsave(&ctx->ctx_lock, flags); 880 /* set this inside the lock so that we can't race with aio_run_iocb() 881 * testing it and putting the iocb on the run list under the lock */ 882 if (!kiocbTryKick(iocb)) 883 run = __queue_kicked_iocb(iocb); 884 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 885 if (run) 886 aio_queue_work(ctx); 887 } 888 889 /* 890 * kick_iocb: 891 * Called typically from a wait queue callback context 892 * (aio_wake_function) to trigger a retry of the iocb. 893 * The retry is usually executed by aio workqueue 894 * threads (See aio_kick_handler). 895 */ 896 void fastcall kick_iocb(struct kiocb *iocb) 897 { 898 /* sync iocbs are easy: they can only ever be executing from a 899 * single context. */ 900 if (is_sync_kiocb(iocb)) { 901 kiocbSetKicked(iocb); 902 wake_up_process(iocb->ki_obj.tsk); 903 return; 904 } 905 906 try_queue_kicked_iocb(iocb); 907 } 908 EXPORT_SYMBOL(kick_iocb); 909 910 /* aio_complete 911 * Called when the io request on the given iocb is complete. 912 * Returns true if this is the last user of the request. The 913 * only other user of the request can be the cancellation code. 914 */ 915 int fastcall aio_complete(struct kiocb *iocb, long res, long res2) 916 { 917 struct kioctx *ctx = iocb->ki_ctx; 918 struct aio_ring_info *info; 919 struct aio_ring *ring; 920 struct io_event *event; 921 unsigned long flags; 922 unsigned long tail; 923 int ret; 924 925 /* 926 * Special case handling for sync iocbs: 927 * - events go directly into the iocb for fast handling 928 * - the sync task with the iocb in its stack holds the single iocb 929 * ref, no other paths have a way to get another ref 930 * - the sync task helpfully left a reference to itself in the iocb 931 */ 932 if (is_sync_kiocb(iocb)) { 933 BUG_ON(iocb->ki_users != 1); 934 iocb->ki_user_data = res; 935 iocb->ki_users = 0; 936 wake_up_process(iocb->ki_obj.tsk); 937 return 1; 938 } 939 940 /* 941 * Check if the user asked us to deliver the result through an 942 * eventfd. The eventfd_signal() function is safe to be called 943 * from IRQ context. 944 */ 945 if (!IS_ERR(iocb->ki_eventfd)) 946 eventfd_signal(iocb->ki_eventfd, 1); 947 948 info = &ctx->ring_info; 949 950 /* add a completion event to the ring buffer. 951 * must be done holding ctx->ctx_lock to prevent 952 * other code from messing with the tail 953 * pointer since we might be called from irq 954 * context. 955 */ 956 spin_lock_irqsave(&ctx->ctx_lock, flags); 957 958 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) 959 list_del_init(&iocb->ki_run_list); 960 961 /* 962 * cancelled requests don't get events, userland was given one 963 * when the event got cancelled. 964 */ 965 if (kiocbIsCancelled(iocb)) 966 goto put_rq; 967 968 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); 969 970 tail = info->tail; 971 event = aio_ring_event(info, tail, KM_IRQ0); 972 if (++tail >= info->nr) 973 tail = 0; 974 975 event->obj = (u64)(unsigned long)iocb->ki_obj.user; 976 event->data = iocb->ki_user_data; 977 event->res = res; 978 event->res2 = res2; 979 980 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", 981 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, 982 res, res2); 983 984 /* after flagging the request as done, we 985 * must never even look at it again 986 */ 987 smp_wmb(); /* make event visible before updating tail */ 988 989 info->tail = tail; 990 ring->tail = tail; 991 992 put_aio_ring_event(event, KM_IRQ0); 993 kunmap_atomic(ring, KM_IRQ1); 994 995 pr_debug("added to ring %p at [%lu]\n", iocb, tail); 996 put_rq: 997 /* everything turned out well, dispose of the aiocb. */ 998 ret = __aio_put_req(ctx, iocb); 999 1000 if (waitqueue_active(&ctx->wait)) 1001 wake_up(&ctx->wait); 1002 1003 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 1004 return ret; 1005 } 1006 1007 /* aio_read_evt 1008 * Pull an event off of the ioctx's event ring. Returns the number of 1009 * events fetched (0 or 1 ;-) 1010 * FIXME: make this use cmpxchg. 1011 * TODO: make the ringbuffer user mmap()able (requires FIXME). 1012 */ 1013 static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) 1014 { 1015 struct aio_ring_info *info = &ioctx->ring_info; 1016 struct aio_ring *ring; 1017 unsigned long head; 1018 int ret = 0; 1019 1020 ring = kmap_atomic(info->ring_pages[0], KM_USER0); 1021 dprintk("in aio_read_evt h%lu t%lu m%lu\n", 1022 (unsigned long)ring->head, (unsigned long)ring->tail, 1023 (unsigned long)ring->nr); 1024 1025 if (ring->head == ring->tail) 1026 goto out; 1027 1028 spin_lock(&info->ring_lock); 1029 1030 head = ring->head % info->nr; 1031 if (head != ring->tail) { 1032 struct io_event *evp = aio_ring_event(info, head, KM_USER1); 1033 *ent = *evp; 1034 head = (head + 1) % info->nr; 1035 smp_mb(); /* finish reading the event before updatng the head */ 1036 ring->head = head; 1037 ret = 1; 1038 put_aio_ring_event(evp, KM_USER1); 1039 } 1040 spin_unlock(&info->ring_lock); 1041 1042 out: 1043 kunmap_atomic(ring, KM_USER0); 1044 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, 1045 (unsigned long)ring->head, (unsigned long)ring->tail); 1046 return ret; 1047 } 1048 1049 struct aio_timeout { 1050 struct timer_list timer; 1051 int timed_out; 1052 struct task_struct *p; 1053 }; 1054 1055 static void timeout_func(unsigned long data) 1056 { 1057 struct aio_timeout *to = (struct aio_timeout *)data; 1058 1059 to->timed_out = 1; 1060 wake_up_process(to->p); 1061 } 1062 1063 static inline void init_timeout(struct aio_timeout *to) 1064 { 1065 init_timer(&to->timer); 1066 to->timer.data = (unsigned long)to; 1067 to->timer.function = timeout_func; 1068 to->timed_out = 0; 1069 to->p = current; 1070 } 1071 1072 static inline void set_timeout(long start_jiffies, struct aio_timeout *to, 1073 const struct timespec *ts) 1074 { 1075 to->timer.expires = start_jiffies + timespec_to_jiffies(ts); 1076 if (time_after(to->timer.expires, jiffies)) 1077 add_timer(&to->timer); 1078 else 1079 to->timed_out = 1; 1080 } 1081 1082 static inline void clear_timeout(struct aio_timeout *to) 1083 { 1084 del_singleshot_timer_sync(&to->timer); 1085 } 1086 1087 static int read_events(struct kioctx *ctx, 1088 long min_nr, long nr, 1089 struct io_event __user *event, 1090 struct timespec __user *timeout) 1091 { 1092 long start_jiffies = jiffies; 1093 struct task_struct *tsk = current; 1094 DECLARE_WAITQUEUE(wait, tsk); 1095 int ret; 1096 int i = 0; 1097 struct io_event ent; 1098 struct aio_timeout to; 1099 int retry = 0; 1100 1101 /* needed to zero any padding within an entry (there shouldn't be 1102 * any, but C is fun! 1103 */ 1104 memset(&ent, 0, sizeof(ent)); 1105 retry: 1106 ret = 0; 1107 while (likely(i < nr)) { 1108 ret = aio_read_evt(ctx, &ent); 1109 if (unlikely(ret <= 0)) 1110 break; 1111 1112 dprintk("read event: %Lx %Lx %Lx %Lx\n", 1113 ent.data, ent.obj, ent.res, ent.res2); 1114 1115 /* Could we split the check in two? */ 1116 ret = -EFAULT; 1117 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1118 dprintk("aio: lost an event due to EFAULT.\n"); 1119 break; 1120 } 1121 ret = 0; 1122 1123 /* Good, event copied to userland, update counts. */ 1124 event ++; 1125 i ++; 1126 } 1127 1128 if (min_nr <= i) 1129 return i; 1130 if (ret) 1131 return ret; 1132 1133 /* End fast path */ 1134 1135 /* racey check, but it gets redone */ 1136 if (!retry && unlikely(!list_empty(&ctx->run_list))) { 1137 retry = 1; 1138 aio_run_all_iocbs(ctx); 1139 goto retry; 1140 } 1141 1142 init_timeout(&to); 1143 if (timeout) { 1144 struct timespec ts; 1145 ret = -EFAULT; 1146 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) 1147 goto out; 1148 1149 set_timeout(start_jiffies, &to, &ts); 1150 } 1151 1152 while (likely(i < nr)) { 1153 add_wait_queue_exclusive(&ctx->wait, &wait); 1154 do { 1155 set_task_state(tsk, TASK_INTERRUPTIBLE); 1156 ret = aio_read_evt(ctx, &ent); 1157 if (ret) 1158 break; 1159 if (min_nr <= i) 1160 break; 1161 ret = 0; 1162 if (to.timed_out) /* Only check after read evt */ 1163 break; 1164 /* Try to only show up in io wait if there are ops 1165 * in flight */ 1166 if (ctx->reqs_active) 1167 io_schedule(); 1168 else 1169 schedule(); 1170 if (signal_pending(tsk)) { 1171 ret = -EINTR; 1172 break; 1173 } 1174 /*ret = aio_read_evt(ctx, &ent);*/ 1175 } while (1) ; 1176 1177 set_task_state(tsk, TASK_RUNNING); 1178 remove_wait_queue(&ctx->wait, &wait); 1179 1180 if (unlikely(ret <= 0)) 1181 break; 1182 1183 ret = -EFAULT; 1184 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1185 dprintk("aio: lost an event due to EFAULT.\n"); 1186 break; 1187 } 1188 1189 /* Good, event copied to userland, update counts. */ 1190 event ++; 1191 i ++; 1192 } 1193 1194 if (timeout) 1195 clear_timeout(&to); 1196 out: 1197 return i ? i : ret; 1198 } 1199 1200 /* Take an ioctx and remove it from the list of ioctx's. Protects 1201 * against races with itself via ->dead. 1202 */ 1203 static void io_destroy(struct kioctx *ioctx) 1204 { 1205 struct mm_struct *mm = current->mm; 1206 struct kioctx **tmp; 1207 int was_dead; 1208 1209 /* delete the entry from the list is someone else hasn't already */ 1210 write_lock(&mm->ioctx_list_lock); 1211 was_dead = ioctx->dead; 1212 ioctx->dead = 1; 1213 for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx; 1214 tmp = &(*tmp)->next) 1215 ; 1216 if (*tmp) 1217 *tmp = ioctx->next; 1218 write_unlock(&mm->ioctx_list_lock); 1219 1220 dprintk("aio_release(%p)\n", ioctx); 1221 if (likely(!was_dead)) 1222 put_ioctx(ioctx); /* twice for the list */ 1223 1224 aio_cancel_all(ioctx); 1225 wait_for_all_aios(ioctx); 1226 put_ioctx(ioctx); /* once for the lookup */ 1227 } 1228 1229 /* sys_io_setup: 1230 * Create an aio_context capable of receiving at least nr_events. 1231 * ctxp must not point to an aio_context that already exists, and 1232 * must be initialized to 0 prior to the call. On successful 1233 * creation of the aio_context, *ctxp is filled in with the resulting 1234 * handle. May fail with -EINVAL if *ctxp is not initialized, 1235 * if the specified nr_events exceeds internal limits. May fail 1236 * with -EAGAIN if the specified nr_events exceeds the user's limit 1237 * of available events. May fail with -ENOMEM if insufficient kernel 1238 * resources are available. May fail with -EFAULT if an invalid 1239 * pointer is passed for ctxp. Will fail with -ENOSYS if not 1240 * implemented. 1241 */ 1242 asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp) 1243 { 1244 struct kioctx *ioctx = NULL; 1245 unsigned long ctx; 1246 long ret; 1247 1248 ret = get_user(ctx, ctxp); 1249 if (unlikely(ret)) 1250 goto out; 1251 1252 ret = -EINVAL; 1253 if (unlikely(ctx || nr_events == 0)) { 1254 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n", 1255 ctx, nr_events); 1256 goto out; 1257 } 1258 1259 ioctx = ioctx_alloc(nr_events); 1260 ret = PTR_ERR(ioctx); 1261 if (!IS_ERR(ioctx)) { 1262 ret = put_user(ioctx->user_id, ctxp); 1263 if (!ret) 1264 return 0; 1265 1266 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ 1267 io_destroy(ioctx); 1268 } 1269 1270 out: 1271 return ret; 1272 } 1273 1274 /* sys_io_destroy: 1275 * Destroy the aio_context specified. May cancel any outstanding 1276 * AIOs and block on completion. Will fail with -ENOSYS if not 1277 * implemented. May fail with -EFAULT if the context pointed to 1278 * is invalid. 1279 */ 1280 asmlinkage long sys_io_destroy(aio_context_t ctx) 1281 { 1282 struct kioctx *ioctx = lookup_ioctx(ctx); 1283 if (likely(NULL != ioctx)) { 1284 io_destroy(ioctx); 1285 return 0; 1286 } 1287 pr_debug("EINVAL: io_destroy: invalid context id\n"); 1288 return -EINVAL; 1289 } 1290 1291 static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret) 1292 { 1293 struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg]; 1294 1295 BUG_ON(ret <= 0); 1296 1297 while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) { 1298 ssize_t this = min((ssize_t)iov->iov_len, ret); 1299 iov->iov_base += this; 1300 iov->iov_len -= this; 1301 iocb->ki_left -= this; 1302 ret -= this; 1303 if (iov->iov_len == 0) { 1304 iocb->ki_cur_seg++; 1305 iov++; 1306 } 1307 } 1308 1309 /* the caller should not have done more io than what fit in 1310 * the remaining iovecs */ 1311 BUG_ON(ret > 0 && iocb->ki_left == 0); 1312 } 1313 1314 static ssize_t aio_rw_vect_retry(struct kiocb *iocb) 1315 { 1316 struct file *file = iocb->ki_filp; 1317 struct address_space *mapping = file->f_mapping; 1318 struct inode *inode = mapping->host; 1319 ssize_t (*rw_op)(struct kiocb *, const struct iovec *, 1320 unsigned long, loff_t); 1321 ssize_t ret = 0; 1322 unsigned short opcode; 1323 1324 if ((iocb->ki_opcode == IOCB_CMD_PREADV) || 1325 (iocb->ki_opcode == IOCB_CMD_PREAD)) { 1326 rw_op = file->f_op->aio_read; 1327 opcode = IOCB_CMD_PREADV; 1328 } else { 1329 rw_op = file->f_op->aio_write; 1330 opcode = IOCB_CMD_PWRITEV; 1331 } 1332 1333 do { 1334 ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg], 1335 iocb->ki_nr_segs - iocb->ki_cur_seg, 1336 iocb->ki_pos); 1337 if (ret > 0) 1338 aio_advance_iovec(iocb, ret); 1339 1340 /* retry all partial writes. retry partial reads as long as its a 1341 * regular file. */ 1342 } while (ret > 0 && iocb->ki_left > 0 && 1343 (opcode == IOCB_CMD_PWRITEV || 1344 (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)))); 1345 1346 /* This means we must have transferred all that we could */ 1347 /* No need to retry anymore */ 1348 if ((ret == 0) || (iocb->ki_left == 0)) 1349 ret = iocb->ki_nbytes - iocb->ki_left; 1350 1351 return ret; 1352 } 1353 1354 static ssize_t aio_fdsync(struct kiocb *iocb) 1355 { 1356 struct file *file = iocb->ki_filp; 1357 ssize_t ret = -EINVAL; 1358 1359 if (file->f_op->aio_fsync) 1360 ret = file->f_op->aio_fsync(iocb, 1); 1361 return ret; 1362 } 1363 1364 static ssize_t aio_fsync(struct kiocb *iocb) 1365 { 1366 struct file *file = iocb->ki_filp; 1367 ssize_t ret = -EINVAL; 1368 1369 if (file->f_op->aio_fsync) 1370 ret = file->f_op->aio_fsync(iocb, 0); 1371 return ret; 1372 } 1373 1374 static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb) 1375 { 1376 ssize_t ret; 1377 1378 ret = rw_copy_check_uvector(type, (struct iovec __user *)kiocb->ki_buf, 1379 kiocb->ki_nbytes, 1, 1380 &kiocb->ki_inline_vec, &kiocb->ki_iovec); 1381 if (ret < 0) 1382 goto out; 1383 1384 kiocb->ki_nr_segs = kiocb->ki_nbytes; 1385 kiocb->ki_cur_seg = 0; 1386 /* ki_nbytes/left now reflect bytes instead of segs */ 1387 kiocb->ki_nbytes = ret; 1388 kiocb->ki_left = ret; 1389 1390 ret = 0; 1391 out: 1392 return ret; 1393 } 1394 1395 static ssize_t aio_setup_single_vector(struct kiocb *kiocb) 1396 { 1397 kiocb->ki_iovec = &kiocb->ki_inline_vec; 1398 kiocb->ki_iovec->iov_base = kiocb->ki_buf; 1399 kiocb->ki_iovec->iov_len = kiocb->ki_left; 1400 kiocb->ki_nr_segs = 1; 1401 kiocb->ki_cur_seg = 0; 1402 return 0; 1403 } 1404 1405 /* 1406 * aio_setup_iocb: 1407 * Performs the initial checks and aio retry method 1408 * setup for the kiocb at the time of io submission. 1409 */ 1410 static ssize_t aio_setup_iocb(struct kiocb *kiocb) 1411 { 1412 struct file *file = kiocb->ki_filp; 1413 ssize_t ret = 0; 1414 1415 switch (kiocb->ki_opcode) { 1416 case IOCB_CMD_PREAD: 1417 ret = -EBADF; 1418 if (unlikely(!(file->f_mode & FMODE_READ))) 1419 break; 1420 ret = -EFAULT; 1421 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, 1422 kiocb->ki_left))) 1423 break; 1424 ret = security_file_permission(file, MAY_READ); 1425 if (unlikely(ret)) 1426 break; 1427 ret = aio_setup_single_vector(kiocb); 1428 if (ret) 1429 break; 1430 ret = -EINVAL; 1431 if (file->f_op->aio_read) 1432 kiocb->ki_retry = aio_rw_vect_retry; 1433 break; 1434 case IOCB_CMD_PWRITE: 1435 ret = -EBADF; 1436 if (unlikely(!(file->f_mode & FMODE_WRITE))) 1437 break; 1438 ret = -EFAULT; 1439 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, 1440 kiocb->ki_left))) 1441 break; 1442 ret = security_file_permission(file, MAY_WRITE); 1443 if (unlikely(ret)) 1444 break; 1445 ret = aio_setup_single_vector(kiocb); 1446 if (ret) 1447 break; 1448 ret = -EINVAL; 1449 if (file->f_op->aio_write) 1450 kiocb->ki_retry = aio_rw_vect_retry; 1451 break; 1452 case IOCB_CMD_PREADV: 1453 ret = -EBADF; 1454 if (unlikely(!(file->f_mode & FMODE_READ))) 1455 break; 1456 ret = security_file_permission(file, MAY_READ); 1457 if (unlikely(ret)) 1458 break; 1459 ret = aio_setup_vectored_rw(READ, kiocb); 1460 if (ret) 1461 break; 1462 ret = -EINVAL; 1463 if (file->f_op->aio_read) 1464 kiocb->ki_retry = aio_rw_vect_retry; 1465 break; 1466 case IOCB_CMD_PWRITEV: 1467 ret = -EBADF; 1468 if (unlikely(!(file->f_mode & FMODE_WRITE))) 1469 break; 1470 ret = security_file_permission(file, MAY_WRITE); 1471 if (unlikely(ret)) 1472 break; 1473 ret = aio_setup_vectored_rw(WRITE, kiocb); 1474 if (ret) 1475 break; 1476 ret = -EINVAL; 1477 if (file->f_op->aio_write) 1478 kiocb->ki_retry = aio_rw_vect_retry; 1479 break; 1480 case IOCB_CMD_FDSYNC: 1481 ret = -EINVAL; 1482 if (file->f_op->aio_fsync) 1483 kiocb->ki_retry = aio_fdsync; 1484 break; 1485 case IOCB_CMD_FSYNC: 1486 ret = -EINVAL; 1487 if (file->f_op->aio_fsync) 1488 kiocb->ki_retry = aio_fsync; 1489 break; 1490 default: 1491 dprintk("EINVAL: io_submit: no operation provided\n"); 1492 ret = -EINVAL; 1493 } 1494 1495 if (!kiocb->ki_retry) 1496 return ret; 1497 1498 return 0; 1499 } 1500 1501 /* 1502 * aio_wake_function: 1503 * wait queue callback function for aio notification, 1504 * Simply triggers a retry of the operation via kick_iocb. 1505 * 1506 * This callback is specified in the wait queue entry in 1507 * a kiocb. 1508 * 1509 * Note: 1510 * This routine is executed with the wait queue lock held. 1511 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests 1512 * the ioctx lock inside the wait queue lock. This is safe 1513 * because this callback isn't used for wait queues which 1514 * are nested inside ioctx lock (i.e. ctx->wait) 1515 */ 1516 static int aio_wake_function(wait_queue_t *wait, unsigned mode, 1517 int sync, void *key) 1518 { 1519 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); 1520 1521 list_del_init(&wait->task_list); 1522 kick_iocb(iocb); 1523 return 1; 1524 } 1525 1526 int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1527 struct iocb *iocb) 1528 { 1529 struct kiocb *req; 1530 struct file *file; 1531 ssize_t ret; 1532 1533 /* enforce forwards compatibility on users */ 1534 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) { 1535 pr_debug("EINVAL: io_submit: reserve field set\n"); 1536 return -EINVAL; 1537 } 1538 1539 /* prevent overflows */ 1540 if (unlikely( 1541 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1542 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1543 ((ssize_t)iocb->aio_nbytes < 0) 1544 )) { 1545 pr_debug("EINVAL: io_submit: overflow check\n"); 1546 return -EINVAL; 1547 } 1548 1549 file = fget(iocb->aio_fildes); 1550 if (unlikely(!file)) 1551 return -EBADF; 1552 1553 req = aio_get_req(ctx); /* returns with 2 references to req */ 1554 if (unlikely(!req)) { 1555 fput(file); 1556 return -EAGAIN; 1557 } 1558 req->ki_filp = file; 1559 if (iocb->aio_flags & IOCB_FLAG_RESFD) { 1560 /* 1561 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an 1562 * instance of the file* now. The file descriptor must be 1563 * an eventfd() fd, and will be signaled for each completed 1564 * event using the eventfd_signal() function. 1565 */ 1566 req->ki_eventfd = eventfd_fget((int) iocb->aio_resfd); 1567 if (unlikely(IS_ERR(req->ki_eventfd))) { 1568 ret = PTR_ERR(req->ki_eventfd); 1569 goto out_put_req; 1570 } 1571 } 1572 1573 ret = put_user(req->ki_key, &user_iocb->aio_key); 1574 if (unlikely(ret)) { 1575 dprintk("EFAULT: aio_key\n"); 1576 goto out_put_req; 1577 } 1578 1579 req->ki_obj.user = user_iocb; 1580 req->ki_user_data = iocb->aio_data; 1581 req->ki_pos = iocb->aio_offset; 1582 1583 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; 1584 req->ki_left = req->ki_nbytes = iocb->aio_nbytes; 1585 req->ki_opcode = iocb->aio_lio_opcode; 1586 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); 1587 INIT_LIST_HEAD(&req->ki_wait.task_list); 1588 1589 ret = aio_setup_iocb(req); 1590 1591 if (ret) 1592 goto out_put_req; 1593 1594 spin_lock_irq(&ctx->ctx_lock); 1595 aio_run_iocb(req); 1596 if (!list_empty(&ctx->run_list)) { 1597 /* drain the run list */ 1598 while (__aio_run_iocbs(ctx)) 1599 ; 1600 } 1601 spin_unlock_irq(&ctx->ctx_lock); 1602 aio_put_req(req); /* drop extra ref to req */ 1603 return 0; 1604 1605 out_put_req: 1606 aio_put_req(req); /* drop extra ref to req */ 1607 aio_put_req(req); /* drop i/o ref to req */ 1608 return ret; 1609 } 1610 1611 /* sys_io_submit: 1612 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1613 * the number of iocbs queued. May return -EINVAL if the aio_context 1614 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1615 * *iocbpp[0] is not properly initialized, if the operation specified 1616 * is invalid for the file descriptor in the iocb. May fail with 1617 * -EFAULT if any of the data structures point to invalid data. May 1618 * fail with -EBADF if the file descriptor specified in the first 1619 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1620 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1621 * fail with -ENOSYS if not implemented. 1622 */ 1623 asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, 1624 struct iocb __user * __user *iocbpp) 1625 { 1626 struct kioctx *ctx; 1627 long ret = 0; 1628 int i; 1629 1630 if (unlikely(nr < 0)) 1631 return -EINVAL; 1632 1633 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1634 return -EFAULT; 1635 1636 ctx = lookup_ioctx(ctx_id); 1637 if (unlikely(!ctx)) { 1638 pr_debug("EINVAL: io_submit: invalid context id\n"); 1639 return -EINVAL; 1640 } 1641 1642 /* 1643 * AKPM: should this return a partial result if some of the IOs were 1644 * successfully submitted? 1645 */ 1646 for (i=0; i<nr; i++) { 1647 struct iocb __user *user_iocb; 1648 struct iocb tmp; 1649 1650 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1651 ret = -EFAULT; 1652 break; 1653 } 1654 1655 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1656 ret = -EFAULT; 1657 break; 1658 } 1659 1660 ret = io_submit_one(ctx, user_iocb, &tmp); 1661 if (ret) 1662 break; 1663 } 1664 1665 put_ioctx(ctx); 1666 return i ? i : ret; 1667 } 1668 1669 /* lookup_kiocb 1670 * Finds a given iocb for cancellation. 1671 */ 1672 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 1673 u32 key) 1674 { 1675 struct list_head *pos; 1676 1677 assert_spin_locked(&ctx->ctx_lock); 1678 1679 /* TODO: use a hash or array, this sucks. */ 1680 list_for_each(pos, &ctx->active_reqs) { 1681 struct kiocb *kiocb = list_kiocb(pos); 1682 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) 1683 return kiocb; 1684 } 1685 return NULL; 1686 } 1687 1688 /* sys_io_cancel: 1689 * Attempts to cancel an iocb previously passed to io_submit. If 1690 * the operation is successfully cancelled, the resulting event is 1691 * copied into the memory pointed to by result without being placed 1692 * into the completion queue and 0 is returned. May fail with 1693 * -EFAULT if any of the data structures pointed to are invalid. 1694 * May fail with -EINVAL if aio_context specified by ctx_id is 1695 * invalid. May fail with -EAGAIN if the iocb specified was not 1696 * cancelled. Will fail with -ENOSYS if not implemented. 1697 */ 1698 asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, 1699 struct io_event __user *result) 1700 { 1701 int (*cancel)(struct kiocb *iocb, struct io_event *res); 1702 struct kioctx *ctx; 1703 struct kiocb *kiocb; 1704 u32 key; 1705 int ret; 1706 1707 ret = get_user(key, &iocb->aio_key); 1708 if (unlikely(ret)) 1709 return -EFAULT; 1710 1711 ctx = lookup_ioctx(ctx_id); 1712 if (unlikely(!ctx)) 1713 return -EINVAL; 1714 1715 spin_lock_irq(&ctx->ctx_lock); 1716 ret = -EAGAIN; 1717 kiocb = lookup_kiocb(ctx, iocb, key); 1718 if (kiocb && kiocb->ki_cancel) { 1719 cancel = kiocb->ki_cancel; 1720 kiocb->ki_users ++; 1721 kiocbSetCancelled(kiocb); 1722 } else 1723 cancel = NULL; 1724 spin_unlock_irq(&ctx->ctx_lock); 1725 1726 if (NULL != cancel) { 1727 struct io_event tmp; 1728 pr_debug("calling cancel\n"); 1729 memset(&tmp, 0, sizeof(tmp)); 1730 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; 1731 tmp.data = kiocb->ki_user_data; 1732 ret = cancel(kiocb, &tmp); 1733 if (!ret) { 1734 /* Cancellation succeeded -- copy the result 1735 * into the user's buffer. 1736 */ 1737 if (copy_to_user(result, &tmp, sizeof(tmp))) 1738 ret = -EFAULT; 1739 } 1740 } else 1741 ret = -EINVAL; 1742 1743 put_ioctx(ctx); 1744 1745 return ret; 1746 } 1747 1748 /* io_getevents: 1749 * Attempts to read at least min_nr events and up to nr events from 1750 * the completion queue for the aio_context specified by ctx_id. May 1751 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, 1752 * if nr is out of range, if when is out of range. May fail with 1753 * -EFAULT if any of the memory specified to is invalid. May return 1754 * 0 or < min_nr if no events are available and the timeout specified 1755 * by when has elapsed, where when == NULL specifies an infinite 1756 * timeout. Note that the timeout pointed to by when is relative and 1757 * will be updated if not NULL and the operation blocks. Will fail 1758 * with -ENOSYS if not implemented. 1759 */ 1760 asmlinkage long sys_io_getevents(aio_context_t ctx_id, 1761 long min_nr, 1762 long nr, 1763 struct io_event __user *events, 1764 struct timespec __user *timeout) 1765 { 1766 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1767 long ret = -EINVAL; 1768 1769 if (likely(ioctx)) { 1770 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) 1771 ret = read_events(ioctx, min_nr, nr, events, timeout); 1772 put_ioctx(ioctx); 1773 } 1774 1775 return ret; 1776 } 1777 1778 __initcall(aio_setup); 1779 1780 EXPORT_SYMBOL(aio_complete); 1781 EXPORT_SYMBOL(aio_put_req); 1782 EXPORT_SYMBOL(wait_on_sync_kiocb); 1783