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 19 #define DEBUG 0 20 21 #include <linux/sched.h> 22 #include <linux/fs.h> 23 #include <linux/file.h> 24 #include <linux/mm.h> 25 #include <linux/mman.h> 26 #include <linux/slab.h> 27 #include <linux/timer.h> 28 #include <linux/aio.h> 29 #include <linux/highmem.h> 30 #include <linux/workqueue.h> 31 #include <linux/security.h> 32 33 #include <asm/kmap_types.h> 34 #include <asm/uaccess.h> 35 #include <asm/mmu_context.h> 36 37 #if DEBUG > 1 38 #define dprintk printk 39 #else 40 #define dprintk(x...) do { ; } while (0) 41 #endif 42 43 /*------ sysctl variables----*/ 44 static DEFINE_SPINLOCK(aio_nr_lock); 45 unsigned long aio_nr; /* current system wide number of aio requests */ 46 unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ 47 /*----end sysctl variables---*/ 48 49 static kmem_cache_t *kiocb_cachep; 50 static kmem_cache_t *kioctx_cachep; 51 52 static struct workqueue_struct *aio_wq; 53 54 /* Used for rare fput completion. */ 55 static void aio_fput_routine(void *); 56 static DECLARE_WORK(fput_work, aio_fput_routine, NULL); 57 58 static DEFINE_SPINLOCK(fput_lock); 59 static LIST_HEAD(fput_head); 60 61 static void aio_kick_handler(void *); 62 static void aio_queue_work(struct kioctx *); 63 64 /* aio_setup 65 * Creates the slab caches used by the aio routines, panic on 66 * failure as this is done early during the boot sequence. 67 */ 68 static int __init aio_setup(void) 69 { 70 kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb), 71 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 72 kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx), 73 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 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_ANON|MAP_PRIVATE, 135 0); 136 if (IS_ERR((void *)info->mmap_base)) { 137 up_write(&ctx->mm->mmap_sem); 138 printk("mmap err: %ld\n", -info->mmap_base); 139 info->mmap_size = 0; 140 aio_free_ring(ctx); 141 return -EAGAIN; 142 } 143 144 dprintk("mmap address: 0x%08lx\n", info->mmap_base); 145 info->nr_pages = get_user_pages(current, ctx->mm, 146 info->mmap_base, nr_pages, 147 1, 0, info->ring_pages, NULL); 148 up_write(&ctx->mm->mmap_sem); 149 150 if (unlikely(info->nr_pages != nr_pages)) { 151 aio_free_ring(ctx); 152 return -EAGAIN; 153 } 154 155 ctx->user_id = info->mmap_base; 156 157 info->nr = nr_events; /* trusted copy */ 158 159 ring = kmap_atomic(info->ring_pages[0], KM_USER0); 160 ring->nr = nr_events; /* user copy */ 161 ring->id = ctx->user_id; 162 ring->head = ring->tail = 0; 163 ring->magic = AIO_RING_MAGIC; 164 ring->compat_features = AIO_RING_COMPAT_FEATURES; 165 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; 166 ring->header_length = sizeof(struct aio_ring); 167 kunmap_atomic(ring, KM_USER0); 168 169 return 0; 170 } 171 172 173 /* aio_ring_event: returns a pointer to the event at the given index from 174 * kmap_atomic(, km). Release the pointer with put_aio_ring_event(); 175 */ 176 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) 177 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) 178 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) 179 180 #define aio_ring_event(info, nr, km) ({ \ 181 unsigned pos = (nr) + AIO_EVENTS_OFFSET; \ 182 struct io_event *__event; \ 183 __event = kmap_atomic( \ 184 (info)->ring_pages[pos / AIO_EVENTS_PER_PAGE], km); \ 185 __event += pos % AIO_EVENTS_PER_PAGE; \ 186 __event; \ 187 }) 188 189 #define put_aio_ring_event(event, km) do { \ 190 struct io_event *__event = (event); \ 191 (void)__event; \ 192 kunmap_atomic((void *)((unsigned long)__event & PAGE_MASK), km); \ 193 } while(0) 194 195 /* ioctx_alloc 196 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. 197 */ 198 static struct kioctx *ioctx_alloc(unsigned nr_events) 199 { 200 struct mm_struct *mm; 201 struct kioctx *ctx; 202 203 /* Prevent overflows */ 204 if ((nr_events > (0x10000000U / sizeof(struct io_event))) || 205 (nr_events > (0x10000000U / sizeof(struct kiocb)))) { 206 pr_debug("ENOMEM: nr_events too high\n"); 207 return ERR_PTR(-EINVAL); 208 } 209 210 if ((unsigned long)nr_events > aio_max_nr) 211 return ERR_PTR(-EAGAIN); 212 213 ctx = kmem_cache_alloc(kioctx_cachep, GFP_KERNEL); 214 if (!ctx) 215 return ERR_PTR(-ENOMEM); 216 217 memset(ctx, 0, sizeof(*ctx)); 218 ctx->max_reqs = nr_events; 219 mm = ctx->mm = current->mm; 220 atomic_inc(&mm->mm_count); 221 222 atomic_set(&ctx->users, 1); 223 spin_lock_init(&ctx->ctx_lock); 224 spin_lock_init(&ctx->ring_info.ring_lock); 225 init_waitqueue_head(&ctx->wait); 226 227 INIT_LIST_HEAD(&ctx->active_reqs); 228 INIT_LIST_HEAD(&ctx->run_list); 229 INIT_WORK(&ctx->wq, aio_kick_handler, ctx); 230 231 if (aio_setup_ring(ctx) < 0) 232 goto out_freectx; 233 234 /* limit the number of system wide aios */ 235 spin_lock(&aio_nr_lock); 236 if (aio_nr + ctx->max_reqs > aio_max_nr || 237 aio_nr + ctx->max_reqs < aio_nr) 238 ctx->max_reqs = 0; 239 else 240 aio_nr += ctx->max_reqs; 241 spin_unlock(&aio_nr_lock); 242 if (ctx->max_reqs == 0) 243 goto out_cleanup; 244 245 /* now link into global list. kludge. FIXME */ 246 write_lock(&mm->ioctx_list_lock); 247 ctx->next = mm->ioctx_list; 248 mm->ioctx_list = ctx; 249 write_unlock(&mm->ioctx_list_lock); 250 251 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", 252 ctx, ctx->user_id, current->mm, ctx->ring_info.nr); 253 return ctx; 254 255 out_cleanup: 256 __put_ioctx(ctx); 257 return ERR_PTR(-EAGAIN); 258 259 out_freectx: 260 mmdrop(mm); 261 kmem_cache_free(kioctx_cachep, ctx); 262 ctx = ERR_PTR(-ENOMEM); 263 264 dprintk("aio: error allocating ioctx %p\n", ctx); 265 return ctx; 266 } 267 268 /* aio_cancel_all 269 * Cancels all outstanding aio requests on an aio context. Used 270 * when the processes owning a context have all exited to encourage 271 * the rapid destruction of the kioctx. 272 */ 273 static void aio_cancel_all(struct kioctx *ctx) 274 { 275 int (*cancel)(struct kiocb *, struct io_event *); 276 struct io_event res; 277 spin_lock_irq(&ctx->ctx_lock); 278 ctx->dead = 1; 279 while (!list_empty(&ctx->active_reqs)) { 280 struct list_head *pos = ctx->active_reqs.next; 281 struct kiocb *iocb = list_kiocb(pos); 282 list_del_init(&iocb->ki_list); 283 cancel = iocb->ki_cancel; 284 kiocbSetCancelled(iocb); 285 if (cancel) { 286 iocb->ki_users++; 287 spin_unlock_irq(&ctx->ctx_lock); 288 cancel(iocb, &res); 289 spin_lock_irq(&ctx->ctx_lock); 290 } 291 } 292 spin_unlock_irq(&ctx->ctx_lock); 293 } 294 295 static void wait_for_all_aios(struct kioctx *ctx) 296 { 297 struct task_struct *tsk = current; 298 DECLARE_WAITQUEUE(wait, tsk); 299 300 if (!ctx->reqs_active) 301 return; 302 303 add_wait_queue(&ctx->wait, &wait); 304 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 305 while (ctx->reqs_active) { 306 schedule(); 307 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 308 } 309 __set_task_state(tsk, TASK_RUNNING); 310 remove_wait_queue(&ctx->wait, &wait); 311 } 312 313 /* wait_on_sync_kiocb: 314 * Waits on the given sync kiocb to complete. 315 */ 316 ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb) 317 { 318 while (iocb->ki_users) { 319 set_current_state(TASK_UNINTERRUPTIBLE); 320 if (!iocb->ki_users) 321 break; 322 schedule(); 323 } 324 __set_current_state(TASK_RUNNING); 325 return iocb->ki_user_data; 326 } 327 328 /* exit_aio: called when the last user of mm goes away. At this point, 329 * there is no way for any new requests to be submited or any of the 330 * io_* syscalls to be called on the context. However, there may be 331 * outstanding requests which hold references to the context; as they 332 * go away, they will call put_ioctx and release any pinned memory 333 * associated with the request (held via struct page * references). 334 */ 335 void fastcall exit_aio(struct mm_struct *mm) 336 { 337 struct kioctx *ctx = mm->ioctx_list; 338 mm->ioctx_list = NULL; 339 while (ctx) { 340 struct kioctx *next = ctx->next; 341 ctx->next = NULL; 342 aio_cancel_all(ctx); 343 344 wait_for_all_aios(ctx); 345 /* 346 * this is an overkill, but ensures we don't leave 347 * the ctx on the aio_wq 348 */ 349 flush_workqueue(aio_wq); 350 351 if (1 != atomic_read(&ctx->users)) 352 printk(KERN_DEBUG 353 "exit_aio:ioctx still alive: %d %d %d\n", 354 atomic_read(&ctx->users), ctx->dead, 355 ctx->reqs_active); 356 put_ioctx(ctx); 357 ctx = next; 358 } 359 } 360 361 /* __put_ioctx 362 * Called when the last user of an aio context has gone away, 363 * and the struct needs to be freed. 364 */ 365 void fastcall __put_ioctx(struct kioctx *ctx) 366 { 367 unsigned nr_events = ctx->max_reqs; 368 369 if (unlikely(ctx->reqs_active)) 370 BUG(); 371 372 cancel_delayed_work(&ctx->wq); 373 flush_workqueue(aio_wq); 374 aio_free_ring(ctx); 375 mmdrop(ctx->mm); 376 ctx->mm = NULL; 377 pr_debug("__put_ioctx: freeing %p\n", ctx); 378 kmem_cache_free(kioctx_cachep, ctx); 379 380 if (nr_events) { 381 spin_lock(&aio_nr_lock); 382 BUG_ON(aio_nr - nr_events > aio_nr); 383 aio_nr -= nr_events; 384 spin_unlock(&aio_nr_lock); 385 } 386 } 387 388 /* aio_get_req 389 * Allocate a slot for an aio request. Increments the users count 390 * of the kioctx so that the kioctx stays around until all requests are 391 * complete. Returns NULL if no requests are free. 392 * 393 * Returns with kiocb->users set to 2. The io submit code path holds 394 * an extra reference while submitting the i/o. 395 * This prevents races between the aio code path referencing the 396 * req (after submitting it) and aio_complete() freeing the req. 397 */ 398 static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx)); 399 static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx) 400 { 401 struct kiocb *req = NULL; 402 struct aio_ring *ring; 403 int okay = 0; 404 405 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); 406 if (unlikely(!req)) 407 return NULL; 408 409 req->ki_flags = 0; 410 req->ki_users = 2; 411 req->ki_key = 0; 412 req->ki_ctx = ctx; 413 req->ki_cancel = NULL; 414 req->ki_retry = NULL; 415 req->ki_dtor = NULL; 416 req->private = NULL; 417 INIT_LIST_HEAD(&req->ki_run_list); 418 419 /* Check if the completion queue has enough free space to 420 * accept an event from this io. 421 */ 422 spin_lock_irq(&ctx->ctx_lock); 423 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); 424 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { 425 list_add(&req->ki_list, &ctx->active_reqs); 426 get_ioctx(ctx); 427 ctx->reqs_active++; 428 okay = 1; 429 } 430 kunmap_atomic(ring, KM_USER0); 431 spin_unlock_irq(&ctx->ctx_lock); 432 433 if (!okay) { 434 kmem_cache_free(kiocb_cachep, req); 435 req = NULL; 436 } 437 438 return req; 439 } 440 441 static inline struct kiocb *aio_get_req(struct kioctx *ctx) 442 { 443 struct kiocb *req; 444 /* Handle a potential starvation case -- should be exceedingly rare as 445 * requests will be stuck on fput_head only if the aio_fput_routine is 446 * delayed and the requests were the last user of the struct file. 447 */ 448 req = __aio_get_req(ctx); 449 if (unlikely(NULL == req)) { 450 aio_fput_routine(NULL); 451 req = __aio_get_req(ctx); 452 } 453 return req; 454 } 455 456 static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) 457 { 458 assert_spin_locked(&ctx->ctx_lock); 459 460 if (req->ki_dtor) 461 req->ki_dtor(req); 462 kmem_cache_free(kiocb_cachep, req); 463 ctx->reqs_active--; 464 465 if (unlikely(!ctx->reqs_active && ctx->dead)) 466 wake_up(&ctx->wait); 467 } 468 469 static void aio_fput_routine(void *data) 470 { 471 spin_lock_irq(&fput_lock); 472 while (likely(!list_empty(&fput_head))) { 473 struct kiocb *req = list_kiocb(fput_head.next); 474 struct kioctx *ctx = req->ki_ctx; 475 476 list_del(&req->ki_list); 477 spin_unlock_irq(&fput_lock); 478 479 /* Complete the fput */ 480 __fput(req->ki_filp); 481 482 /* Link the iocb into the context's free list */ 483 spin_lock_irq(&ctx->ctx_lock); 484 really_put_req(ctx, req); 485 spin_unlock_irq(&ctx->ctx_lock); 486 487 put_ioctx(ctx); 488 spin_lock_irq(&fput_lock); 489 } 490 spin_unlock_irq(&fput_lock); 491 } 492 493 /* __aio_put_req 494 * Returns true if this put was the last user of the request. 495 */ 496 static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) 497 { 498 dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n", 499 req, atomic_read(&req->ki_filp->f_count)); 500 501 assert_spin_locked(&ctx->ctx_lock); 502 503 req->ki_users --; 504 if (unlikely(req->ki_users < 0)) 505 BUG(); 506 if (likely(req->ki_users)) 507 return 0; 508 list_del(&req->ki_list); /* remove from active_reqs */ 509 req->ki_cancel = NULL; 510 req->ki_retry = NULL; 511 512 /* Must be done under the lock to serialise against cancellation. 513 * Call this aio_fput as it duplicates fput via the fput_work. 514 */ 515 if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) { 516 get_ioctx(ctx); 517 spin_lock(&fput_lock); 518 list_add(&req->ki_list, &fput_head); 519 spin_unlock(&fput_lock); 520 queue_work(aio_wq, &fput_work); 521 } else 522 really_put_req(ctx, req); 523 return 1; 524 } 525 526 /* aio_put_req 527 * Returns true if this put was the last user of the kiocb, 528 * false if the request is still in use. 529 */ 530 int fastcall aio_put_req(struct kiocb *req) 531 { 532 struct kioctx *ctx = req->ki_ctx; 533 int ret; 534 spin_lock_irq(&ctx->ctx_lock); 535 ret = __aio_put_req(ctx, req); 536 spin_unlock_irq(&ctx->ctx_lock); 537 if (ret) 538 put_ioctx(ctx); 539 return ret; 540 } 541 542 /* Lookup an ioctx id. ioctx_list is lockless for reads. 543 * FIXME: this is O(n) and is only suitable for development. 544 */ 545 struct kioctx *lookup_ioctx(unsigned long ctx_id) 546 { 547 struct kioctx *ioctx; 548 struct mm_struct *mm; 549 550 mm = current->mm; 551 read_lock(&mm->ioctx_list_lock); 552 for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next) 553 if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) { 554 get_ioctx(ioctx); 555 break; 556 } 557 read_unlock(&mm->ioctx_list_lock); 558 559 return ioctx; 560 } 561 562 /* 563 * use_mm 564 * Makes the calling kernel thread take on the specified 565 * mm context. 566 * Called by the retry thread execute retries within the 567 * iocb issuer's mm context, so that copy_from/to_user 568 * operations work seamlessly for aio. 569 * (Note: this routine is intended to be called only 570 * from a kernel thread context) 571 */ 572 static void use_mm(struct mm_struct *mm) 573 { 574 struct mm_struct *active_mm; 575 struct task_struct *tsk = current; 576 577 task_lock(tsk); 578 tsk->flags |= PF_BORROWED_MM; 579 active_mm = tsk->active_mm; 580 atomic_inc(&mm->mm_count); 581 tsk->mm = mm; 582 tsk->active_mm = mm; 583 /* 584 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise 585 * it won't work. Update it accordingly if you change it here 586 */ 587 activate_mm(active_mm, mm); 588 task_unlock(tsk); 589 590 mmdrop(active_mm); 591 } 592 593 /* 594 * unuse_mm 595 * Reverses the effect of use_mm, i.e. releases the 596 * specified mm context which was earlier taken on 597 * by the calling kernel thread 598 * (Note: this routine is intended to be called only 599 * from a kernel thread context) 600 * 601 * Comments: Called with ctx->ctx_lock held. This nests 602 * task_lock instead ctx_lock. 603 */ 604 static void unuse_mm(struct mm_struct *mm) 605 { 606 struct task_struct *tsk = current; 607 608 task_lock(tsk); 609 tsk->flags &= ~PF_BORROWED_MM; 610 tsk->mm = NULL; 611 /* active_mm is still 'mm' */ 612 enter_lazy_tlb(mm, tsk); 613 task_unlock(tsk); 614 } 615 616 /* 617 * Queue up a kiocb to be retried. Assumes that the kiocb 618 * has already been marked as kicked, and places it on 619 * the retry run list for the corresponding ioctx, if it 620 * isn't already queued. Returns 1 if it actually queued 621 * the kiocb (to tell the caller to activate the work 622 * queue to process it), or 0, if it found that it was 623 * already queued. 624 */ 625 static inline int __queue_kicked_iocb(struct kiocb *iocb) 626 { 627 struct kioctx *ctx = iocb->ki_ctx; 628 629 assert_spin_locked(&ctx->ctx_lock); 630 631 if (list_empty(&iocb->ki_run_list)) { 632 list_add_tail(&iocb->ki_run_list, 633 &ctx->run_list); 634 return 1; 635 } 636 return 0; 637 } 638 639 /* aio_run_iocb 640 * This is the core aio execution routine. It is 641 * invoked both for initial i/o submission and 642 * subsequent retries via the aio_kick_handler. 643 * Expects to be invoked with iocb->ki_ctx->lock 644 * already held. The lock is released and reaquired 645 * as needed during processing. 646 * 647 * Calls the iocb retry method (already setup for the 648 * iocb on initial submission) for operation specific 649 * handling, but takes care of most of common retry 650 * execution details for a given iocb. The retry method 651 * needs to be non-blocking as far as possible, to avoid 652 * holding up other iocbs waiting to be serviced by the 653 * retry kernel thread. 654 * 655 * The trickier parts in this code have to do with 656 * ensuring that only one retry instance is in progress 657 * for a given iocb at any time. Providing that guarantee 658 * simplifies the coding of individual aio operations as 659 * it avoids various potential races. 660 */ 661 static ssize_t aio_run_iocb(struct kiocb *iocb) 662 { 663 struct kioctx *ctx = iocb->ki_ctx; 664 ssize_t (*retry)(struct kiocb *); 665 ssize_t ret; 666 667 if (iocb->ki_retried++ > 1024*1024) { 668 printk("Maximal retry count. Bytes done %Zd\n", 669 iocb->ki_nbytes - iocb->ki_left); 670 return -EAGAIN; 671 } 672 673 if (!(iocb->ki_retried & 0xff)) { 674 pr_debug("%ld retry: %d of %d\n", iocb->ki_retried, 675 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); 676 } 677 678 if (!(retry = iocb->ki_retry)) { 679 printk("aio_run_iocb: iocb->ki_retry = NULL\n"); 680 return 0; 681 } 682 683 /* 684 * We don't want the next retry iteration for this 685 * operation to start until this one has returned and 686 * updated the iocb state. However, wait_queue functions 687 * can trigger a kick_iocb from interrupt context in the 688 * meantime, indicating that data is available for the next 689 * iteration. We want to remember that and enable the 690 * next retry iteration _after_ we are through with 691 * this one. 692 * 693 * So, in order to be able to register a "kick", but 694 * prevent it from being queued now, we clear the kick 695 * flag, but make the kick code *think* that the iocb is 696 * still on the run list until we are actually done. 697 * When we are done with this iteration, we check if 698 * the iocb was kicked in the meantime and if so, queue 699 * it up afresh. 700 */ 701 702 kiocbClearKicked(iocb); 703 704 /* 705 * This is so that aio_complete knows it doesn't need to 706 * pull the iocb off the run list (We can't just call 707 * INIT_LIST_HEAD because we don't want a kick_iocb to 708 * queue this on the run list yet) 709 */ 710 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; 711 spin_unlock_irq(&ctx->ctx_lock); 712 713 /* Quit retrying if the i/o has been cancelled */ 714 if (kiocbIsCancelled(iocb)) { 715 ret = -EINTR; 716 aio_complete(iocb, ret, 0); 717 /* must not access the iocb after this */ 718 goto out; 719 } 720 721 /* 722 * Now we are all set to call the retry method in async 723 * context. By setting this thread's io_wait context 724 * to point to the wait queue entry inside the currently 725 * running iocb for the duration of the retry, we ensure 726 * that async notification wakeups are queued by the 727 * operation instead of blocking waits, and when notified, 728 * cause the iocb to be kicked for continuation (through 729 * the aio_wake_function callback). 730 */ 731 BUG_ON(current->io_wait != NULL); 732 current->io_wait = &iocb->ki_wait; 733 ret = retry(iocb); 734 current->io_wait = NULL; 735 736 if (ret != -EIOCBRETRY && ret != -EIOCBQUEUED) { 737 BUG_ON(!list_empty(&iocb->ki_wait.task_list)); 738 aio_complete(iocb, ret, 0); 739 } 740 out: 741 spin_lock_irq(&ctx->ctx_lock); 742 743 if (-EIOCBRETRY == ret) { 744 /* 745 * OK, now that we are done with this iteration 746 * and know that there is more left to go, 747 * this is where we let go so that a subsequent 748 * "kick" can start the next iteration 749 */ 750 751 /* will make __queue_kicked_iocb succeed from here on */ 752 INIT_LIST_HEAD(&iocb->ki_run_list); 753 /* we must queue the next iteration ourselves, if it 754 * has already been kicked */ 755 if (kiocbIsKicked(iocb)) { 756 __queue_kicked_iocb(iocb); 757 758 /* 759 * __queue_kicked_iocb will always return 1 here, because 760 * iocb->ki_run_list is empty at this point so it should 761 * be safe to unconditionally queue the context into the 762 * work queue. 763 */ 764 aio_queue_work(ctx); 765 } 766 } 767 return ret; 768 } 769 770 /* 771 * __aio_run_iocbs: 772 * Process all pending retries queued on the ioctx 773 * run list. 774 * Assumes it is operating within the aio issuer's mm 775 * context. 776 */ 777 static int __aio_run_iocbs(struct kioctx *ctx) 778 { 779 struct kiocb *iocb; 780 LIST_HEAD(run_list); 781 782 assert_spin_locked(&ctx->ctx_lock); 783 784 list_splice_init(&ctx->run_list, &run_list); 785 while (!list_empty(&run_list)) { 786 iocb = list_entry(run_list.next, struct kiocb, 787 ki_run_list); 788 list_del(&iocb->ki_run_list); 789 /* 790 * Hold an extra reference while retrying i/o. 791 */ 792 iocb->ki_users++; /* grab extra reference */ 793 aio_run_iocb(iocb); 794 if (__aio_put_req(ctx, iocb)) /* drop extra ref */ 795 put_ioctx(ctx); 796 } 797 if (!list_empty(&ctx->run_list)) 798 return 1; 799 return 0; 800 } 801 802 static void aio_queue_work(struct kioctx * ctx) 803 { 804 unsigned long timeout; 805 /* 806 * if someone is waiting, get the work started right 807 * away, otherwise, use a longer delay 808 */ 809 smp_mb(); 810 if (waitqueue_active(&ctx->wait)) 811 timeout = 1; 812 else 813 timeout = HZ/10; 814 queue_delayed_work(aio_wq, &ctx->wq, timeout); 815 } 816 817 818 /* 819 * aio_run_iocbs: 820 * Process all pending retries queued on the ioctx 821 * run list. 822 * Assumes it is operating within the aio issuer's mm 823 * context. 824 */ 825 static inline void aio_run_iocbs(struct kioctx *ctx) 826 { 827 int requeue; 828 829 spin_lock_irq(&ctx->ctx_lock); 830 831 requeue = __aio_run_iocbs(ctx); 832 spin_unlock_irq(&ctx->ctx_lock); 833 if (requeue) 834 aio_queue_work(ctx); 835 } 836 837 /* 838 * just like aio_run_iocbs, but keeps running them until 839 * the list stays empty 840 */ 841 static inline void aio_run_all_iocbs(struct kioctx *ctx) 842 { 843 spin_lock_irq(&ctx->ctx_lock); 844 while (__aio_run_iocbs(ctx)) 845 ; 846 spin_unlock_irq(&ctx->ctx_lock); 847 } 848 849 /* 850 * aio_kick_handler: 851 * Work queue handler triggered to process pending 852 * retries on an ioctx. Takes on the aio issuer's 853 * mm context before running the iocbs, so that 854 * copy_xxx_user operates on the issuer's address 855 * space. 856 * Run on aiod's context. 857 */ 858 static void aio_kick_handler(void *data) 859 { 860 struct kioctx *ctx = data; 861 mm_segment_t oldfs = get_fs(); 862 int requeue; 863 864 set_fs(USER_DS); 865 use_mm(ctx->mm); 866 spin_lock_irq(&ctx->ctx_lock); 867 requeue =__aio_run_iocbs(ctx); 868 unuse_mm(ctx->mm); 869 spin_unlock_irq(&ctx->ctx_lock); 870 set_fs(oldfs); 871 /* 872 * we're in a worker thread already, don't use queue_delayed_work, 873 */ 874 if (requeue) 875 queue_work(aio_wq, &ctx->wq); 876 } 877 878 879 /* 880 * Called by kick_iocb to queue the kiocb for retry 881 * and if required activate the aio work queue to process 882 * it 883 */ 884 static void try_queue_kicked_iocb(struct kiocb *iocb) 885 { 886 struct kioctx *ctx = iocb->ki_ctx; 887 unsigned long flags; 888 int run = 0; 889 890 /* We're supposed to be the only path putting the iocb back on the run 891 * list. If we find that the iocb is *back* on a wait queue already 892 * than retry has happened before we could queue the iocb. This also 893 * means that the retry could have completed and freed our iocb, no 894 * good. */ 895 BUG_ON((!list_empty(&iocb->ki_wait.task_list))); 896 897 spin_lock_irqsave(&ctx->ctx_lock, flags); 898 /* set this inside the lock so that we can't race with aio_run_iocb() 899 * testing it and putting the iocb on the run list under the lock */ 900 if (!kiocbTryKick(iocb)) 901 run = __queue_kicked_iocb(iocb); 902 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 903 if (run) 904 aio_queue_work(ctx); 905 } 906 907 /* 908 * kick_iocb: 909 * Called typically from a wait queue callback context 910 * (aio_wake_function) to trigger a retry of the iocb. 911 * The retry is usually executed by aio workqueue 912 * threads (See aio_kick_handler). 913 */ 914 void fastcall kick_iocb(struct kiocb *iocb) 915 { 916 /* sync iocbs are easy: they can only ever be executing from a 917 * single context. */ 918 if (is_sync_kiocb(iocb)) { 919 kiocbSetKicked(iocb); 920 wake_up_process(iocb->ki_obj.tsk); 921 return; 922 } 923 924 try_queue_kicked_iocb(iocb); 925 } 926 EXPORT_SYMBOL(kick_iocb); 927 928 /* aio_complete 929 * Called when the io request on the given iocb is complete. 930 * Returns true if this is the last user of the request. The 931 * only other user of the request can be the cancellation code. 932 */ 933 int fastcall aio_complete(struct kiocb *iocb, long res, long res2) 934 { 935 struct kioctx *ctx = iocb->ki_ctx; 936 struct aio_ring_info *info; 937 struct aio_ring *ring; 938 struct io_event *event; 939 unsigned long flags; 940 unsigned long tail; 941 int ret; 942 943 /* 944 * Special case handling for sync iocbs: 945 * - events go directly into the iocb for fast handling 946 * - the sync task with the iocb in its stack holds the single iocb 947 * ref, no other paths have a way to get another ref 948 * - the sync task helpfully left a reference to itself in the iocb 949 */ 950 if (is_sync_kiocb(iocb)) { 951 BUG_ON(iocb->ki_users != 1); 952 iocb->ki_user_data = res; 953 iocb->ki_users = 0; 954 wake_up_process(iocb->ki_obj.tsk); 955 return 1; 956 } 957 958 info = &ctx->ring_info; 959 960 /* add a completion event to the ring buffer. 961 * must be done holding ctx->ctx_lock to prevent 962 * other code from messing with the tail 963 * pointer since we might be called from irq 964 * context. 965 */ 966 spin_lock_irqsave(&ctx->ctx_lock, flags); 967 968 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) 969 list_del_init(&iocb->ki_run_list); 970 971 /* 972 * cancelled requests don't get events, userland was given one 973 * when the event got cancelled. 974 */ 975 if (kiocbIsCancelled(iocb)) 976 goto put_rq; 977 978 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); 979 980 tail = info->tail; 981 event = aio_ring_event(info, tail, KM_IRQ0); 982 if (++tail >= info->nr) 983 tail = 0; 984 985 event->obj = (u64)(unsigned long)iocb->ki_obj.user; 986 event->data = iocb->ki_user_data; 987 event->res = res; 988 event->res2 = res2; 989 990 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", 991 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, 992 res, res2); 993 994 /* after flagging the request as done, we 995 * must never even look at it again 996 */ 997 smp_wmb(); /* make event visible before updating tail */ 998 999 info->tail = tail; 1000 ring->tail = tail; 1001 1002 put_aio_ring_event(event, KM_IRQ0); 1003 kunmap_atomic(ring, KM_IRQ1); 1004 1005 pr_debug("added to ring %p at [%lu]\n", iocb, tail); 1006 1007 pr_debug("%ld retries: %d of %d\n", iocb->ki_retried, 1008 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); 1009 put_rq: 1010 /* everything turned out well, dispose of the aiocb. */ 1011 ret = __aio_put_req(ctx, iocb); 1012 1013 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 1014 1015 if (waitqueue_active(&ctx->wait)) 1016 wake_up(&ctx->wait); 1017 1018 if (ret) 1019 put_ioctx(ctx); 1020 1021 return ret; 1022 } 1023 1024 /* aio_read_evt 1025 * Pull an event off of the ioctx's event ring. Returns the number of 1026 * events fetched (0 or 1 ;-) 1027 * FIXME: make this use cmpxchg. 1028 * TODO: make the ringbuffer user mmap()able (requires FIXME). 1029 */ 1030 static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) 1031 { 1032 struct aio_ring_info *info = &ioctx->ring_info; 1033 struct aio_ring *ring; 1034 unsigned long head; 1035 int ret = 0; 1036 1037 ring = kmap_atomic(info->ring_pages[0], KM_USER0); 1038 dprintk("in aio_read_evt h%lu t%lu m%lu\n", 1039 (unsigned long)ring->head, (unsigned long)ring->tail, 1040 (unsigned long)ring->nr); 1041 1042 if (ring->head == ring->tail) 1043 goto out; 1044 1045 spin_lock(&info->ring_lock); 1046 1047 head = ring->head % info->nr; 1048 if (head != ring->tail) { 1049 struct io_event *evp = aio_ring_event(info, head, KM_USER1); 1050 *ent = *evp; 1051 head = (head + 1) % info->nr; 1052 smp_mb(); /* finish reading the event before updatng the head */ 1053 ring->head = head; 1054 ret = 1; 1055 put_aio_ring_event(evp, KM_USER1); 1056 } 1057 spin_unlock(&info->ring_lock); 1058 1059 out: 1060 kunmap_atomic(ring, KM_USER0); 1061 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, 1062 (unsigned long)ring->head, (unsigned long)ring->tail); 1063 return ret; 1064 } 1065 1066 struct aio_timeout { 1067 struct timer_list timer; 1068 int timed_out; 1069 struct task_struct *p; 1070 }; 1071 1072 static void timeout_func(unsigned long data) 1073 { 1074 struct aio_timeout *to = (struct aio_timeout *)data; 1075 1076 to->timed_out = 1; 1077 wake_up_process(to->p); 1078 } 1079 1080 static inline void init_timeout(struct aio_timeout *to) 1081 { 1082 init_timer(&to->timer); 1083 to->timer.data = (unsigned long)to; 1084 to->timer.function = timeout_func; 1085 to->timed_out = 0; 1086 to->p = current; 1087 } 1088 1089 static inline void set_timeout(long start_jiffies, struct aio_timeout *to, 1090 const struct timespec *ts) 1091 { 1092 to->timer.expires = start_jiffies + timespec_to_jiffies(ts); 1093 if (time_after(to->timer.expires, jiffies)) 1094 add_timer(&to->timer); 1095 else 1096 to->timed_out = 1; 1097 } 1098 1099 static inline void clear_timeout(struct aio_timeout *to) 1100 { 1101 del_singleshot_timer_sync(&to->timer); 1102 } 1103 1104 static int read_events(struct kioctx *ctx, 1105 long min_nr, long nr, 1106 struct io_event __user *event, 1107 struct timespec __user *timeout) 1108 { 1109 long start_jiffies = jiffies; 1110 struct task_struct *tsk = current; 1111 DECLARE_WAITQUEUE(wait, tsk); 1112 int ret; 1113 int i = 0; 1114 struct io_event ent; 1115 struct aio_timeout to; 1116 int retry = 0; 1117 1118 /* needed to zero any padding within an entry (there shouldn't be 1119 * any, but C is fun! 1120 */ 1121 memset(&ent, 0, sizeof(ent)); 1122 retry: 1123 ret = 0; 1124 while (likely(i < nr)) { 1125 ret = aio_read_evt(ctx, &ent); 1126 if (unlikely(ret <= 0)) 1127 break; 1128 1129 dprintk("read event: %Lx %Lx %Lx %Lx\n", 1130 ent.data, ent.obj, ent.res, ent.res2); 1131 1132 /* Could we split the check in two? */ 1133 ret = -EFAULT; 1134 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1135 dprintk("aio: lost an event due to EFAULT.\n"); 1136 break; 1137 } 1138 ret = 0; 1139 1140 /* Good, event copied to userland, update counts. */ 1141 event ++; 1142 i ++; 1143 } 1144 1145 if (min_nr <= i) 1146 return i; 1147 if (ret) 1148 return ret; 1149 1150 /* End fast path */ 1151 1152 /* racey check, but it gets redone */ 1153 if (!retry && unlikely(!list_empty(&ctx->run_list))) { 1154 retry = 1; 1155 aio_run_all_iocbs(ctx); 1156 goto retry; 1157 } 1158 1159 init_timeout(&to); 1160 if (timeout) { 1161 struct timespec ts; 1162 ret = -EFAULT; 1163 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) 1164 goto out; 1165 1166 set_timeout(start_jiffies, &to, &ts); 1167 } 1168 1169 while (likely(i < nr)) { 1170 add_wait_queue_exclusive(&ctx->wait, &wait); 1171 do { 1172 set_task_state(tsk, TASK_INTERRUPTIBLE); 1173 ret = aio_read_evt(ctx, &ent); 1174 if (ret) 1175 break; 1176 if (min_nr <= i) 1177 break; 1178 ret = 0; 1179 if (to.timed_out) /* Only check after read evt */ 1180 break; 1181 schedule(); 1182 if (signal_pending(tsk)) { 1183 ret = -EINTR; 1184 break; 1185 } 1186 /*ret = aio_read_evt(ctx, &ent);*/ 1187 } while (1) ; 1188 1189 set_task_state(tsk, TASK_RUNNING); 1190 remove_wait_queue(&ctx->wait, &wait); 1191 1192 if (unlikely(ret <= 0)) 1193 break; 1194 1195 ret = -EFAULT; 1196 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1197 dprintk("aio: lost an event due to EFAULT.\n"); 1198 break; 1199 } 1200 1201 /* Good, event copied to userland, update counts. */ 1202 event ++; 1203 i ++; 1204 } 1205 1206 if (timeout) 1207 clear_timeout(&to); 1208 out: 1209 return i ? i : ret; 1210 } 1211 1212 /* Take an ioctx and remove it from the list of ioctx's. Protects 1213 * against races with itself via ->dead. 1214 */ 1215 static void io_destroy(struct kioctx *ioctx) 1216 { 1217 struct mm_struct *mm = current->mm; 1218 struct kioctx **tmp; 1219 int was_dead; 1220 1221 /* delete the entry from the list is someone else hasn't already */ 1222 write_lock(&mm->ioctx_list_lock); 1223 was_dead = ioctx->dead; 1224 ioctx->dead = 1; 1225 for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx; 1226 tmp = &(*tmp)->next) 1227 ; 1228 if (*tmp) 1229 *tmp = ioctx->next; 1230 write_unlock(&mm->ioctx_list_lock); 1231 1232 dprintk("aio_release(%p)\n", ioctx); 1233 if (likely(!was_dead)) 1234 put_ioctx(ioctx); /* twice for the list */ 1235 1236 aio_cancel_all(ioctx); 1237 wait_for_all_aios(ioctx); 1238 put_ioctx(ioctx); /* once for the lookup */ 1239 } 1240 1241 /* sys_io_setup: 1242 * Create an aio_context capable of receiving at least nr_events. 1243 * ctxp must not point to an aio_context that already exists, and 1244 * must be initialized to 0 prior to the call. On successful 1245 * creation of the aio_context, *ctxp is filled in with the resulting 1246 * handle. May fail with -EINVAL if *ctxp is not initialized, 1247 * if the specified nr_events exceeds internal limits. May fail 1248 * with -EAGAIN if the specified nr_events exceeds the user's limit 1249 * of available events. May fail with -ENOMEM if insufficient kernel 1250 * resources are available. May fail with -EFAULT if an invalid 1251 * pointer is passed for ctxp. Will fail with -ENOSYS if not 1252 * implemented. 1253 */ 1254 asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp) 1255 { 1256 struct kioctx *ioctx = NULL; 1257 unsigned long ctx; 1258 long ret; 1259 1260 ret = get_user(ctx, ctxp); 1261 if (unlikely(ret)) 1262 goto out; 1263 1264 ret = -EINVAL; 1265 if (unlikely(ctx || nr_events == 0)) { 1266 pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n", 1267 ctx, nr_events); 1268 goto out; 1269 } 1270 1271 ioctx = ioctx_alloc(nr_events); 1272 ret = PTR_ERR(ioctx); 1273 if (!IS_ERR(ioctx)) { 1274 ret = put_user(ioctx->user_id, ctxp); 1275 if (!ret) 1276 return 0; 1277 1278 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ 1279 io_destroy(ioctx); 1280 } 1281 1282 out: 1283 return ret; 1284 } 1285 1286 /* sys_io_destroy: 1287 * Destroy the aio_context specified. May cancel any outstanding 1288 * AIOs and block on completion. Will fail with -ENOSYS if not 1289 * implemented. May fail with -EFAULT if the context pointed to 1290 * is invalid. 1291 */ 1292 asmlinkage long sys_io_destroy(aio_context_t ctx) 1293 { 1294 struct kioctx *ioctx = lookup_ioctx(ctx); 1295 if (likely(NULL != ioctx)) { 1296 io_destroy(ioctx); 1297 return 0; 1298 } 1299 pr_debug("EINVAL: io_destroy: invalid context id\n"); 1300 return -EINVAL; 1301 } 1302 1303 /* 1304 * aio_p{read,write} are the default ki_retry methods for 1305 * IO_CMD_P{READ,WRITE}. They maintains kiocb retry state around potentially 1306 * multiple calls to f_op->aio_read(). They loop around partial progress 1307 * instead of returning -EIOCBRETRY because they don't have the means to call 1308 * kick_iocb(). 1309 */ 1310 static ssize_t aio_pread(struct kiocb *iocb) 1311 { 1312 struct file *file = iocb->ki_filp; 1313 struct address_space *mapping = file->f_mapping; 1314 struct inode *inode = mapping->host; 1315 ssize_t ret = 0; 1316 1317 do { 1318 ret = file->f_op->aio_read(iocb, iocb->ki_buf, 1319 iocb->ki_left, iocb->ki_pos); 1320 /* 1321 * Can't just depend on iocb->ki_left to determine 1322 * whether we are done. This may have been a short read. 1323 */ 1324 if (ret > 0) { 1325 iocb->ki_buf += ret; 1326 iocb->ki_left -= ret; 1327 } 1328 1329 /* 1330 * For pipes and sockets we return once we have some data; for 1331 * regular files we retry till we complete the entire read or 1332 * find that we can't read any more data (e.g short reads). 1333 */ 1334 } while (ret > 0 && iocb->ki_left > 0 && 1335 !S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)); 1336 1337 /* This means we must have transferred all that we could */ 1338 /* No need to retry anymore */ 1339 if ((ret == 0) || (iocb->ki_left == 0)) 1340 ret = iocb->ki_nbytes - iocb->ki_left; 1341 1342 return ret; 1343 } 1344 1345 /* see aio_pread() */ 1346 static ssize_t aio_pwrite(struct kiocb *iocb) 1347 { 1348 struct file *file = iocb->ki_filp; 1349 ssize_t ret = 0; 1350 1351 do { 1352 ret = file->f_op->aio_write(iocb, iocb->ki_buf, 1353 iocb->ki_left, iocb->ki_pos); 1354 if (ret > 0) { 1355 iocb->ki_buf += ret; 1356 iocb->ki_left -= ret; 1357 } 1358 } while (ret > 0 && iocb->ki_left > 0); 1359 1360 if ((ret == 0) || (iocb->ki_left == 0)) 1361 ret = iocb->ki_nbytes - iocb->ki_left; 1362 1363 return ret; 1364 } 1365 1366 static ssize_t aio_fdsync(struct kiocb *iocb) 1367 { 1368 struct file *file = iocb->ki_filp; 1369 ssize_t ret = -EINVAL; 1370 1371 if (file->f_op->aio_fsync) 1372 ret = file->f_op->aio_fsync(iocb, 1); 1373 return ret; 1374 } 1375 1376 static ssize_t aio_fsync(struct kiocb *iocb) 1377 { 1378 struct file *file = iocb->ki_filp; 1379 ssize_t ret = -EINVAL; 1380 1381 if (file->f_op->aio_fsync) 1382 ret = file->f_op->aio_fsync(iocb, 0); 1383 return ret; 1384 } 1385 1386 /* 1387 * aio_setup_iocb: 1388 * Performs the initial checks and aio retry method 1389 * setup for the kiocb at the time of io submission. 1390 */ 1391 static ssize_t aio_setup_iocb(struct kiocb *kiocb) 1392 { 1393 struct file *file = kiocb->ki_filp; 1394 ssize_t ret = 0; 1395 1396 switch (kiocb->ki_opcode) { 1397 case IOCB_CMD_PREAD: 1398 ret = -EBADF; 1399 if (unlikely(!(file->f_mode & FMODE_READ))) 1400 break; 1401 ret = -EFAULT; 1402 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, 1403 kiocb->ki_left))) 1404 break; 1405 ret = security_file_permission(file, MAY_READ); 1406 if (unlikely(ret)) 1407 break; 1408 ret = -EINVAL; 1409 if (file->f_op->aio_read) 1410 kiocb->ki_retry = aio_pread; 1411 break; 1412 case IOCB_CMD_PWRITE: 1413 ret = -EBADF; 1414 if (unlikely(!(file->f_mode & FMODE_WRITE))) 1415 break; 1416 ret = -EFAULT; 1417 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, 1418 kiocb->ki_left))) 1419 break; 1420 ret = security_file_permission(file, MAY_WRITE); 1421 if (unlikely(ret)) 1422 break; 1423 ret = -EINVAL; 1424 if (file->f_op->aio_write) 1425 kiocb->ki_retry = aio_pwrite; 1426 break; 1427 case IOCB_CMD_FDSYNC: 1428 ret = -EINVAL; 1429 if (file->f_op->aio_fsync) 1430 kiocb->ki_retry = aio_fdsync; 1431 break; 1432 case IOCB_CMD_FSYNC: 1433 ret = -EINVAL; 1434 if (file->f_op->aio_fsync) 1435 kiocb->ki_retry = aio_fsync; 1436 break; 1437 default: 1438 dprintk("EINVAL: io_submit: no operation provided\n"); 1439 ret = -EINVAL; 1440 } 1441 1442 if (!kiocb->ki_retry) 1443 return ret; 1444 1445 return 0; 1446 } 1447 1448 /* 1449 * aio_wake_function: 1450 * wait queue callback function for aio notification, 1451 * Simply triggers a retry of the operation via kick_iocb. 1452 * 1453 * This callback is specified in the wait queue entry in 1454 * a kiocb (current->io_wait points to this wait queue 1455 * entry when an aio operation executes; it is used 1456 * instead of a synchronous wait when an i/o blocking 1457 * condition is encountered during aio). 1458 * 1459 * Note: 1460 * This routine is executed with the wait queue lock held. 1461 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests 1462 * the ioctx lock inside the wait queue lock. This is safe 1463 * because this callback isn't used for wait queues which 1464 * are nested inside ioctx lock (i.e. ctx->wait) 1465 */ 1466 static int aio_wake_function(wait_queue_t *wait, unsigned mode, 1467 int sync, void *key) 1468 { 1469 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); 1470 1471 list_del_init(&wait->task_list); 1472 kick_iocb(iocb); 1473 return 1; 1474 } 1475 1476 int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1477 struct iocb *iocb) 1478 { 1479 struct kiocb *req; 1480 struct file *file; 1481 ssize_t ret; 1482 1483 /* enforce forwards compatibility on users */ 1484 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || 1485 iocb->aio_reserved3)) { 1486 pr_debug("EINVAL: io_submit: reserve field set\n"); 1487 return -EINVAL; 1488 } 1489 1490 /* prevent overflows */ 1491 if (unlikely( 1492 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1493 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1494 ((ssize_t)iocb->aio_nbytes < 0) 1495 )) { 1496 pr_debug("EINVAL: io_submit: overflow check\n"); 1497 return -EINVAL; 1498 } 1499 1500 file = fget(iocb->aio_fildes); 1501 if (unlikely(!file)) 1502 return -EBADF; 1503 1504 req = aio_get_req(ctx); /* returns with 2 references to req */ 1505 if (unlikely(!req)) { 1506 fput(file); 1507 return -EAGAIN; 1508 } 1509 1510 req->ki_filp = file; 1511 ret = put_user(req->ki_key, &user_iocb->aio_key); 1512 if (unlikely(ret)) { 1513 dprintk("EFAULT: aio_key\n"); 1514 goto out_put_req; 1515 } 1516 1517 req->ki_obj.user = user_iocb; 1518 req->ki_user_data = iocb->aio_data; 1519 req->ki_pos = iocb->aio_offset; 1520 1521 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; 1522 req->ki_left = req->ki_nbytes = iocb->aio_nbytes; 1523 req->ki_opcode = iocb->aio_lio_opcode; 1524 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); 1525 INIT_LIST_HEAD(&req->ki_wait.task_list); 1526 req->ki_retried = 0; 1527 1528 ret = aio_setup_iocb(req); 1529 1530 if (ret) 1531 goto out_put_req; 1532 1533 spin_lock_irq(&ctx->ctx_lock); 1534 aio_run_iocb(req); 1535 if (!list_empty(&ctx->run_list)) { 1536 /* drain the run list */ 1537 while (__aio_run_iocbs(ctx)) 1538 ; 1539 } 1540 spin_unlock_irq(&ctx->ctx_lock); 1541 aio_put_req(req); /* drop extra ref to req */ 1542 return 0; 1543 1544 out_put_req: 1545 aio_put_req(req); /* drop extra ref to req */ 1546 aio_put_req(req); /* drop i/o ref to req */ 1547 return ret; 1548 } 1549 1550 /* sys_io_submit: 1551 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1552 * the number of iocbs queued. May return -EINVAL if the aio_context 1553 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1554 * *iocbpp[0] is not properly initialized, if the operation specified 1555 * is invalid for the file descriptor in the iocb. May fail with 1556 * -EFAULT if any of the data structures point to invalid data. May 1557 * fail with -EBADF if the file descriptor specified in the first 1558 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1559 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1560 * fail with -ENOSYS if not implemented. 1561 */ 1562 asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, 1563 struct iocb __user * __user *iocbpp) 1564 { 1565 struct kioctx *ctx; 1566 long ret = 0; 1567 int i; 1568 1569 if (unlikely(nr < 0)) 1570 return -EINVAL; 1571 1572 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1573 return -EFAULT; 1574 1575 ctx = lookup_ioctx(ctx_id); 1576 if (unlikely(!ctx)) { 1577 pr_debug("EINVAL: io_submit: invalid context id\n"); 1578 return -EINVAL; 1579 } 1580 1581 /* 1582 * AKPM: should this return a partial result if some of the IOs were 1583 * successfully submitted? 1584 */ 1585 for (i=0; i<nr; i++) { 1586 struct iocb __user *user_iocb; 1587 struct iocb tmp; 1588 1589 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1590 ret = -EFAULT; 1591 break; 1592 } 1593 1594 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1595 ret = -EFAULT; 1596 break; 1597 } 1598 1599 ret = io_submit_one(ctx, user_iocb, &tmp); 1600 if (ret) 1601 break; 1602 } 1603 1604 put_ioctx(ctx); 1605 return i ? i : ret; 1606 } 1607 1608 /* lookup_kiocb 1609 * Finds a given iocb for cancellation. 1610 */ 1611 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 1612 u32 key) 1613 { 1614 struct list_head *pos; 1615 1616 assert_spin_locked(&ctx->ctx_lock); 1617 1618 /* TODO: use a hash or array, this sucks. */ 1619 list_for_each(pos, &ctx->active_reqs) { 1620 struct kiocb *kiocb = list_kiocb(pos); 1621 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) 1622 return kiocb; 1623 } 1624 return NULL; 1625 } 1626 1627 /* sys_io_cancel: 1628 * Attempts to cancel an iocb previously passed to io_submit. If 1629 * the operation is successfully cancelled, the resulting event is 1630 * copied into the memory pointed to by result without being placed 1631 * into the completion queue and 0 is returned. May fail with 1632 * -EFAULT if any of the data structures pointed to are invalid. 1633 * May fail with -EINVAL if aio_context specified by ctx_id is 1634 * invalid. May fail with -EAGAIN if the iocb specified was not 1635 * cancelled. Will fail with -ENOSYS if not implemented. 1636 */ 1637 asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, 1638 struct io_event __user *result) 1639 { 1640 int (*cancel)(struct kiocb *iocb, struct io_event *res); 1641 struct kioctx *ctx; 1642 struct kiocb *kiocb; 1643 u32 key; 1644 int ret; 1645 1646 ret = get_user(key, &iocb->aio_key); 1647 if (unlikely(ret)) 1648 return -EFAULT; 1649 1650 ctx = lookup_ioctx(ctx_id); 1651 if (unlikely(!ctx)) 1652 return -EINVAL; 1653 1654 spin_lock_irq(&ctx->ctx_lock); 1655 ret = -EAGAIN; 1656 kiocb = lookup_kiocb(ctx, iocb, key); 1657 if (kiocb && kiocb->ki_cancel) { 1658 cancel = kiocb->ki_cancel; 1659 kiocb->ki_users ++; 1660 kiocbSetCancelled(kiocb); 1661 } else 1662 cancel = NULL; 1663 spin_unlock_irq(&ctx->ctx_lock); 1664 1665 if (NULL != cancel) { 1666 struct io_event tmp; 1667 pr_debug("calling cancel\n"); 1668 memset(&tmp, 0, sizeof(tmp)); 1669 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; 1670 tmp.data = kiocb->ki_user_data; 1671 ret = cancel(kiocb, &tmp); 1672 if (!ret) { 1673 /* Cancellation succeeded -- copy the result 1674 * into the user's buffer. 1675 */ 1676 if (copy_to_user(result, &tmp, sizeof(tmp))) 1677 ret = -EFAULT; 1678 } 1679 } else 1680 ret = -EINVAL; 1681 1682 put_ioctx(ctx); 1683 1684 return ret; 1685 } 1686 1687 /* io_getevents: 1688 * Attempts to read at least min_nr events and up to nr events from 1689 * the completion queue for the aio_context specified by ctx_id. May 1690 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, 1691 * if nr is out of range, if when is out of range. May fail with 1692 * -EFAULT if any of the memory specified to is invalid. May return 1693 * 0 or < min_nr if no events are available and the timeout specified 1694 * by when has elapsed, where when == NULL specifies an infinite 1695 * timeout. Note that the timeout pointed to by when is relative and 1696 * will be updated if not NULL and the operation blocks. Will fail 1697 * with -ENOSYS if not implemented. 1698 */ 1699 asmlinkage long sys_io_getevents(aio_context_t ctx_id, 1700 long min_nr, 1701 long nr, 1702 struct io_event __user *events, 1703 struct timespec __user *timeout) 1704 { 1705 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1706 long ret = -EINVAL; 1707 1708 if (likely(ioctx)) { 1709 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) 1710 ret = read_events(ioctx, min_nr, nr, events, timeout); 1711 put_ioctx(ioctx); 1712 } 1713 1714 return ret; 1715 } 1716 1717 __initcall(aio_setup); 1718 1719 EXPORT_SYMBOL(aio_complete); 1720 EXPORT_SYMBOL(aio_put_req); 1721 EXPORT_SYMBOL(wait_on_sync_kiocb); 1722