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 atomic_t aio_nr = ATOMIC_INIT(0); /* current system wide number of aio requests */ 45 unsigned aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ 46 /*----end sysctl variables---*/ 47 48 static kmem_cache_t *kiocb_cachep; 49 static kmem_cache_t *kioctx_cachep; 50 51 static struct workqueue_struct *aio_wq; 52 53 /* Used for rare fput completion. */ 54 static void aio_fput_routine(void *); 55 static DECLARE_WORK(fput_work, aio_fput_routine, NULL); 56 57 static DEFINE_SPINLOCK(fput_lock); 58 static LIST_HEAD(fput_head); 59 60 static void aio_kick_handler(void *); 61 static void aio_queue_work(struct kioctx *); 62 63 /* aio_setup 64 * Creates the slab caches used by the aio routines, panic on 65 * failure as this is done early during the boot sequence. 66 */ 67 static int __init aio_setup(void) 68 { 69 kiocb_cachep = kmem_cache_create("kiocb", sizeof(struct kiocb), 70 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 71 kioctx_cachep = kmem_cache_create("kioctx", sizeof(struct kioctx), 72 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); 73 74 aio_wq = create_workqueue("aio"); 75 76 pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page)); 77 78 return 0; 79 } 80 81 static void aio_free_ring(struct kioctx *ctx) 82 { 83 struct aio_ring_info *info = &ctx->ring_info; 84 long i; 85 86 for (i=0; i<info->nr_pages; i++) 87 put_page(info->ring_pages[i]); 88 89 if (info->mmap_size) { 90 down_write(&ctx->mm->mmap_sem); 91 do_munmap(ctx->mm, info->mmap_base, info->mmap_size); 92 up_write(&ctx->mm->mmap_sem); 93 } 94 95 if (info->ring_pages && info->ring_pages != info->internal_pages) 96 kfree(info->ring_pages); 97 info->ring_pages = NULL; 98 info->nr = 0; 99 } 100 101 static int aio_setup_ring(struct kioctx *ctx) 102 { 103 struct aio_ring *ring; 104 struct aio_ring_info *info = &ctx->ring_info; 105 unsigned nr_events = ctx->max_reqs; 106 unsigned long size; 107 int nr_pages; 108 109 /* Compensate for the ring buffer's head/tail overlap entry */ 110 nr_events += 2; /* 1 is required, 2 for good luck */ 111 112 size = sizeof(struct aio_ring); 113 size += sizeof(struct io_event) * nr_events; 114 nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; 115 116 if (nr_pages < 0) 117 return -EINVAL; 118 119 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); 120 121 info->nr = 0; 122 info->ring_pages = info->internal_pages; 123 if (nr_pages > AIO_RING_PAGES) { 124 info->ring_pages = kmalloc(sizeof(struct page *) * nr_pages, GFP_KERNEL); 125 if (!info->ring_pages) 126 return -ENOMEM; 127 memset(info->ring_pages, 0, sizeof(struct page *) * nr_pages); 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 (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 atomic_add(ctx->max_reqs, &aio_nr); /* undone by __put_ioctx */ 236 if (unlikely(atomic_read(&aio_nr) > aio_max_nr)) 237 goto out_cleanup; 238 239 /* now link into global list. kludge. FIXME */ 240 write_lock(&mm->ioctx_list_lock); 241 ctx->next = mm->ioctx_list; 242 mm->ioctx_list = ctx; 243 write_unlock(&mm->ioctx_list_lock); 244 245 dprintk("aio: allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", 246 ctx, ctx->user_id, current->mm, ctx->ring_info.nr); 247 return ctx; 248 249 out_cleanup: 250 atomic_sub(ctx->max_reqs, &aio_nr); 251 ctx->max_reqs = 0; /* prevent __put_ioctx from sub'ing aio_nr */ 252 __put_ioctx(ctx); 253 return ERR_PTR(-EAGAIN); 254 255 out_freectx: 256 mmdrop(mm); 257 kmem_cache_free(kioctx_cachep, ctx); 258 ctx = ERR_PTR(-ENOMEM); 259 260 dprintk("aio: error allocating ioctx %p\n", ctx); 261 return ctx; 262 } 263 264 /* aio_cancel_all 265 * Cancels all outstanding aio requests on an aio context. Used 266 * when the processes owning a context have all exited to encourage 267 * the rapid destruction of the kioctx. 268 */ 269 static void aio_cancel_all(struct kioctx *ctx) 270 { 271 int (*cancel)(struct kiocb *, struct io_event *); 272 struct io_event res; 273 spin_lock_irq(&ctx->ctx_lock); 274 ctx->dead = 1; 275 while (!list_empty(&ctx->active_reqs)) { 276 struct list_head *pos = ctx->active_reqs.next; 277 struct kiocb *iocb = list_kiocb(pos); 278 list_del_init(&iocb->ki_list); 279 cancel = iocb->ki_cancel; 280 kiocbSetCancelled(iocb); 281 if (cancel) { 282 iocb->ki_users++; 283 spin_unlock_irq(&ctx->ctx_lock); 284 cancel(iocb, &res); 285 spin_lock_irq(&ctx->ctx_lock); 286 } 287 } 288 spin_unlock_irq(&ctx->ctx_lock); 289 } 290 291 static void wait_for_all_aios(struct kioctx *ctx) 292 { 293 struct task_struct *tsk = current; 294 DECLARE_WAITQUEUE(wait, tsk); 295 296 if (!ctx->reqs_active) 297 return; 298 299 add_wait_queue(&ctx->wait, &wait); 300 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 301 while (ctx->reqs_active) { 302 schedule(); 303 set_task_state(tsk, TASK_UNINTERRUPTIBLE); 304 } 305 __set_task_state(tsk, TASK_RUNNING); 306 remove_wait_queue(&ctx->wait, &wait); 307 } 308 309 /* wait_on_sync_kiocb: 310 * Waits on the given sync kiocb to complete. 311 */ 312 ssize_t fastcall wait_on_sync_kiocb(struct kiocb *iocb) 313 { 314 while (iocb->ki_users) { 315 set_current_state(TASK_UNINTERRUPTIBLE); 316 if (!iocb->ki_users) 317 break; 318 schedule(); 319 } 320 __set_current_state(TASK_RUNNING); 321 return iocb->ki_user_data; 322 } 323 324 /* exit_aio: called when the last user of mm goes away. At this point, 325 * there is no way for any new requests to be submited or any of the 326 * io_* syscalls to be called on the context. However, there may be 327 * outstanding requests which hold references to the context; as they 328 * go away, they will call put_ioctx and release any pinned memory 329 * associated with the request (held via struct page * references). 330 */ 331 void fastcall exit_aio(struct mm_struct *mm) 332 { 333 struct kioctx *ctx = mm->ioctx_list; 334 mm->ioctx_list = NULL; 335 while (ctx) { 336 struct kioctx *next = ctx->next; 337 ctx->next = NULL; 338 aio_cancel_all(ctx); 339 340 wait_for_all_aios(ctx); 341 /* 342 * this is an overkill, but ensures we don't leave 343 * the ctx on the aio_wq 344 */ 345 flush_workqueue(aio_wq); 346 347 if (1 != atomic_read(&ctx->users)) 348 printk(KERN_DEBUG 349 "exit_aio:ioctx still alive: %d %d %d\n", 350 atomic_read(&ctx->users), ctx->dead, 351 ctx->reqs_active); 352 put_ioctx(ctx); 353 ctx = next; 354 } 355 } 356 357 /* __put_ioctx 358 * Called when the last user of an aio context has gone away, 359 * and the struct needs to be freed. 360 */ 361 void fastcall __put_ioctx(struct kioctx *ctx) 362 { 363 unsigned nr_events = ctx->max_reqs; 364 365 if (unlikely(ctx->reqs_active)) 366 BUG(); 367 368 cancel_delayed_work(&ctx->wq); 369 flush_workqueue(aio_wq); 370 aio_free_ring(ctx); 371 mmdrop(ctx->mm); 372 ctx->mm = NULL; 373 pr_debug("__put_ioctx: freeing %p\n", ctx); 374 kmem_cache_free(kioctx_cachep, ctx); 375 376 atomic_sub(nr_events, &aio_nr); 377 } 378 379 /* aio_get_req 380 * Allocate a slot for an aio request. Increments the users count 381 * of the kioctx so that the kioctx stays around until all requests are 382 * complete. Returns NULL if no requests are free. 383 * 384 * Returns with kiocb->users set to 2. The io submit code path holds 385 * an extra reference while submitting the i/o. 386 * This prevents races between the aio code path referencing the 387 * req (after submitting it) and aio_complete() freeing the req. 388 */ 389 static struct kiocb *FASTCALL(__aio_get_req(struct kioctx *ctx)); 390 static struct kiocb fastcall *__aio_get_req(struct kioctx *ctx) 391 { 392 struct kiocb *req = NULL; 393 struct aio_ring *ring; 394 int okay = 0; 395 396 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL); 397 if (unlikely(!req)) 398 return NULL; 399 400 req->ki_flags = 1 << KIF_LOCKED; 401 req->ki_users = 2; 402 req->ki_key = 0; 403 req->ki_ctx = ctx; 404 req->ki_cancel = NULL; 405 req->ki_retry = NULL; 406 req->ki_dtor = NULL; 407 req->private = NULL; 408 INIT_LIST_HEAD(&req->ki_run_list); 409 410 /* Check if the completion queue has enough free space to 411 * accept an event from this io. 412 */ 413 spin_lock_irq(&ctx->ctx_lock); 414 ring = kmap_atomic(ctx->ring_info.ring_pages[0], KM_USER0); 415 if (ctx->reqs_active < aio_ring_avail(&ctx->ring_info, ring)) { 416 list_add(&req->ki_list, &ctx->active_reqs); 417 get_ioctx(ctx); 418 ctx->reqs_active++; 419 okay = 1; 420 } 421 kunmap_atomic(ring, KM_USER0); 422 spin_unlock_irq(&ctx->ctx_lock); 423 424 if (!okay) { 425 kmem_cache_free(kiocb_cachep, req); 426 req = NULL; 427 } 428 429 return req; 430 } 431 432 static inline struct kiocb *aio_get_req(struct kioctx *ctx) 433 { 434 struct kiocb *req; 435 /* Handle a potential starvation case -- should be exceedingly rare as 436 * requests will be stuck on fput_head only if the aio_fput_routine is 437 * delayed and the requests were the last user of the struct file. 438 */ 439 req = __aio_get_req(ctx); 440 if (unlikely(NULL == req)) { 441 aio_fput_routine(NULL); 442 req = __aio_get_req(ctx); 443 } 444 return req; 445 } 446 447 static inline void really_put_req(struct kioctx *ctx, struct kiocb *req) 448 { 449 if (req->ki_dtor) 450 req->ki_dtor(req); 451 kmem_cache_free(kiocb_cachep, req); 452 ctx->reqs_active--; 453 454 if (unlikely(!ctx->reqs_active && ctx->dead)) 455 wake_up(&ctx->wait); 456 } 457 458 static void aio_fput_routine(void *data) 459 { 460 spin_lock_irq(&fput_lock); 461 while (likely(!list_empty(&fput_head))) { 462 struct kiocb *req = list_kiocb(fput_head.next); 463 struct kioctx *ctx = req->ki_ctx; 464 465 list_del(&req->ki_list); 466 spin_unlock_irq(&fput_lock); 467 468 /* Complete the fput */ 469 __fput(req->ki_filp); 470 471 /* Link the iocb into the context's free list */ 472 spin_lock_irq(&ctx->ctx_lock); 473 really_put_req(ctx, req); 474 spin_unlock_irq(&ctx->ctx_lock); 475 476 put_ioctx(ctx); 477 spin_lock_irq(&fput_lock); 478 } 479 spin_unlock_irq(&fput_lock); 480 } 481 482 /* __aio_put_req 483 * Returns true if this put was the last user of the request. 484 */ 485 static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) 486 { 487 dprintk(KERN_DEBUG "aio_put(%p): f_count=%d\n", 488 req, atomic_read(&req->ki_filp->f_count)); 489 490 req->ki_users --; 491 if (unlikely(req->ki_users < 0)) 492 BUG(); 493 if (likely(req->ki_users)) 494 return 0; 495 list_del(&req->ki_list); /* remove from active_reqs */ 496 req->ki_cancel = NULL; 497 req->ki_retry = NULL; 498 499 /* Must be done under the lock to serialise against cancellation. 500 * Call this aio_fput as it duplicates fput via the fput_work. 501 */ 502 if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) { 503 get_ioctx(ctx); 504 spin_lock(&fput_lock); 505 list_add(&req->ki_list, &fput_head); 506 spin_unlock(&fput_lock); 507 queue_work(aio_wq, &fput_work); 508 } else 509 really_put_req(ctx, req); 510 return 1; 511 } 512 513 /* aio_put_req 514 * Returns true if this put was the last user of the kiocb, 515 * false if the request is still in use. 516 */ 517 int fastcall aio_put_req(struct kiocb *req) 518 { 519 struct kioctx *ctx = req->ki_ctx; 520 int ret; 521 spin_lock_irq(&ctx->ctx_lock); 522 ret = __aio_put_req(ctx, req); 523 spin_unlock_irq(&ctx->ctx_lock); 524 if (ret) 525 put_ioctx(ctx); 526 return ret; 527 } 528 529 /* Lookup an ioctx id. ioctx_list is lockless for reads. 530 * FIXME: this is O(n) and is only suitable for development. 531 */ 532 struct kioctx *lookup_ioctx(unsigned long ctx_id) 533 { 534 struct kioctx *ioctx; 535 struct mm_struct *mm; 536 537 mm = current->mm; 538 read_lock(&mm->ioctx_list_lock); 539 for (ioctx = mm->ioctx_list; ioctx; ioctx = ioctx->next) 540 if (likely(ioctx->user_id == ctx_id && !ioctx->dead)) { 541 get_ioctx(ioctx); 542 break; 543 } 544 read_unlock(&mm->ioctx_list_lock); 545 546 return ioctx; 547 } 548 549 /* 550 * use_mm 551 * Makes the calling kernel thread take on the specified 552 * mm context. 553 * Called by the retry thread execute retries within the 554 * iocb issuer's mm context, so that copy_from/to_user 555 * operations work seamlessly for aio. 556 * (Note: this routine is intended to be called only 557 * from a kernel thread context) 558 */ 559 static void use_mm(struct mm_struct *mm) 560 { 561 struct mm_struct *active_mm; 562 struct task_struct *tsk = current; 563 564 task_lock(tsk); 565 tsk->flags |= PF_BORROWED_MM; 566 active_mm = tsk->active_mm; 567 atomic_inc(&mm->mm_count); 568 tsk->mm = mm; 569 tsk->active_mm = mm; 570 /* 571 * Note that on UML this *requires* PF_BORROWED_MM to be set, otherwise 572 * it won't work. Update it accordingly if you change it here 573 */ 574 activate_mm(active_mm, mm); 575 task_unlock(tsk); 576 577 mmdrop(active_mm); 578 } 579 580 /* 581 * unuse_mm 582 * Reverses the effect of use_mm, i.e. releases the 583 * specified mm context which was earlier taken on 584 * by the calling kernel thread 585 * (Note: this routine is intended to be called only 586 * from a kernel thread context) 587 * 588 * Comments: Called with ctx->ctx_lock held. This nests 589 * task_lock instead ctx_lock. 590 */ 591 static void unuse_mm(struct mm_struct *mm) 592 { 593 struct task_struct *tsk = current; 594 595 task_lock(tsk); 596 tsk->flags &= ~PF_BORROWED_MM; 597 tsk->mm = NULL; 598 /* active_mm is still 'mm' */ 599 enter_lazy_tlb(mm, tsk); 600 task_unlock(tsk); 601 } 602 603 /* 604 * Queue up a kiocb to be retried. Assumes that the kiocb 605 * has already been marked as kicked, and places it on 606 * the retry run list for the corresponding ioctx, if it 607 * isn't already queued. Returns 1 if it actually queued 608 * the kiocb (to tell the caller to activate the work 609 * queue to process it), or 0, if it found that it was 610 * already queued. 611 * 612 * Should be called with the spin lock iocb->ki_ctx->ctx_lock 613 * held 614 */ 615 static inline int __queue_kicked_iocb(struct kiocb *iocb) 616 { 617 struct kioctx *ctx = iocb->ki_ctx; 618 619 if (list_empty(&iocb->ki_run_list)) { 620 list_add_tail(&iocb->ki_run_list, 621 &ctx->run_list); 622 return 1; 623 } 624 return 0; 625 } 626 627 /* aio_run_iocb 628 * This is the core aio execution routine. It is 629 * invoked both for initial i/o submission and 630 * subsequent retries via the aio_kick_handler. 631 * Expects to be invoked with iocb->ki_ctx->lock 632 * already held. The lock is released and reaquired 633 * as needed during processing. 634 * 635 * Calls the iocb retry method (already setup for the 636 * iocb on initial submission) for operation specific 637 * handling, but takes care of most of common retry 638 * execution details for a given iocb. The retry method 639 * needs to be non-blocking as far as possible, to avoid 640 * holding up other iocbs waiting to be serviced by the 641 * retry kernel thread. 642 * 643 * The trickier parts in this code have to do with 644 * ensuring that only one retry instance is in progress 645 * for a given iocb at any time. Providing that guarantee 646 * simplifies the coding of individual aio operations as 647 * it avoids various potential races. 648 */ 649 static ssize_t aio_run_iocb(struct kiocb *iocb) 650 { 651 struct kioctx *ctx = iocb->ki_ctx; 652 ssize_t (*retry)(struct kiocb *); 653 ssize_t ret; 654 655 if (iocb->ki_retried++ > 1024*1024) { 656 printk("Maximal retry count. Bytes done %Zd\n", 657 iocb->ki_nbytes - iocb->ki_left); 658 return -EAGAIN; 659 } 660 661 if (!(iocb->ki_retried & 0xff)) { 662 pr_debug("%ld retry: %d of %d\n", iocb->ki_retried, 663 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); 664 } 665 666 if (!(retry = iocb->ki_retry)) { 667 printk("aio_run_iocb: iocb->ki_retry = NULL\n"); 668 return 0; 669 } 670 671 /* 672 * We don't want the next retry iteration for this 673 * operation to start until this one has returned and 674 * updated the iocb state. However, wait_queue functions 675 * can trigger a kick_iocb from interrupt context in the 676 * meantime, indicating that data is available for the next 677 * iteration. We want to remember that and enable the 678 * next retry iteration _after_ we are through with 679 * this one. 680 * 681 * So, in order to be able to register a "kick", but 682 * prevent it from being queued now, we clear the kick 683 * flag, but make the kick code *think* that the iocb is 684 * still on the run list until we are actually done. 685 * When we are done with this iteration, we check if 686 * the iocb was kicked in the meantime and if so, queue 687 * it up afresh. 688 */ 689 690 kiocbClearKicked(iocb); 691 692 /* 693 * This is so that aio_complete knows it doesn't need to 694 * pull the iocb off the run list (We can't just call 695 * INIT_LIST_HEAD because we don't want a kick_iocb to 696 * queue this on the run list yet) 697 */ 698 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; 699 spin_unlock_irq(&ctx->ctx_lock); 700 701 /* Quit retrying if the i/o has been cancelled */ 702 if (kiocbIsCancelled(iocb)) { 703 ret = -EINTR; 704 aio_complete(iocb, ret, 0); 705 /* must not access the iocb after this */ 706 goto out; 707 } 708 709 /* 710 * Now we are all set to call the retry method in async 711 * context. By setting this thread's io_wait context 712 * to point to the wait queue entry inside the currently 713 * running iocb for the duration of the retry, we ensure 714 * that async notification wakeups are queued by the 715 * operation instead of blocking waits, and when notified, 716 * cause the iocb to be kicked for continuation (through 717 * the aio_wake_function callback). 718 */ 719 BUG_ON(current->io_wait != NULL); 720 current->io_wait = &iocb->ki_wait; 721 ret = retry(iocb); 722 current->io_wait = NULL; 723 724 if (-EIOCBRETRY != ret) { 725 if (-EIOCBQUEUED != ret) { 726 BUG_ON(!list_empty(&iocb->ki_wait.task_list)); 727 aio_complete(iocb, ret, 0); 728 /* must not access the iocb after this */ 729 } 730 } else { 731 /* 732 * Issue an additional retry to avoid waiting forever if 733 * no waits were queued (e.g. in case of a short read). 734 */ 735 if (list_empty(&iocb->ki_wait.task_list)) 736 kiocbSetKicked(iocb); 737 } 738 out: 739 spin_lock_irq(&ctx->ctx_lock); 740 741 if (-EIOCBRETRY == ret) { 742 /* 743 * OK, now that we are done with this iteration 744 * and know that there is more left to go, 745 * this is where we let go so that a subsequent 746 * "kick" can start the next iteration 747 */ 748 749 /* will make __queue_kicked_iocb succeed from here on */ 750 INIT_LIST_HEAD(&iocb->ki_run_list); 751 /* we must queue the next iteration ourselves, if it 752 * has already been kicked */ 753 if (kiocbIsKicked(iocb)) { 754 __queue_kicked_iocb(iocb); 755 756 /* 757 * __queue_kicked_iocb will always return 1 here, because 758 * iocb->ki_run_list is empty at this point so it should 759 * be safe to unconditionally queue the context into the 760 * work queue. 761 */ 762 aio_queue_work(ctx); 763 } 764 } 765 return ret; 766 } 767 768 /* 769 * __aio_run_iocbs: 770 * Process all pending retries queued on the ioctx 771 * run list. 772 * Assumes it is operating within the aio issuer's mm 773 * context. Expects to be called with ctx->ctx_lock held 774 */ 775 static int __aio_run_iocbs(struct kioctx *ctx) 776 { 777 struct kiocb *iocb; 778 LIST_HEAD(run_list); 779 780 list_splice_init(&ctx->run_list, &run_list); 781 while (!list_empty(&run_list)) { 782 iocb = list_entry(run_list.next, struct kiocb, 783 ki_run_list); 784 list_del(&iocb->ki_run_list); 785 /* 786 * Hold an extra reference while retrying i/o. 787 */ 788 iocb->ki_users++; /* grab extra reference */ 789 aio_run_iocb(iocb); 790 if (__aio_put_req(ctx, iocb)) /* drop extra ref */ 791 put_ioctx(ctx); 792 } 793 if (!list_empty(&ctx->run_list)) 794 return 1; 795 return 0; 796 } 797 798 static void aio_queue_work(struct kioctx * ctx) 799 { 800 unsigned long timeout; 801 /* 802 * if someone is waiting, get the work started right 803 * away, otherwise, use a longer delay 804 */ 805 smp_mb(); 806 if (waitqueue_active(&ctx->wait)) 807 timeout = 1; 808 else 809 timeout = HZ/10; 810 queue_delayed_work(aio_wq, &ctx->wq, timeout); 811 } 812 813 814 /* 815 * aio_run_iocbs: 816 * Process all pending retries queued on the ioctx 817 * run list. 818 * Assumes it is operating within the aio issuer's mm 819 * context. 820 */ 821 static inline void aio_run_iocbs(struct kioctx *ctx) 822 { 823 int requeue; 824 825 spin_lock_irq(&ctx->ctx_lock); 826 827 requeue = __aio_run_iocbs(ctx); 828 spin_unlock_irq(&ctx->ctx_lock); 829 if (requeue) 830 aio_queue_work(ctx); 831 } 832 833 /* 834 * just like aio_run_iocbs, but keeps running them until 835 * the list stays empty 836 */ 837 static inline void aio_run_all_iocbs(struct kioctx *ctx) 838 { 839 spin_lock_irq(&ctx->ctx_lock); 840 while (__aio_run_iocbs(ctx)) 841 ; 842 spin_unlock_irq(&ctx->ctx_lock); 843 } 844 845 /* 846 * aio_kick_handler: 847 * Work queue handler triggered to process pending 848 * retries on an ioctx. Takes on the aio issuer's 849 * mm context before running the iocbs, so that 850 * copy_xxx_user operates on the issuer's address 851 * space. 852 * Run on aiod's context. 853 */ 854 static void aio_kick_handler(void *data) 855 { 856 struct kioctx *ctx = data; 857 mm_segment_t oldfs = get_fs(); 858 int requeue; 859 860 set_fs(USER_DS); 861 use_mm(ctx->mm); 862 spin_lock_irq(&ctx->ctx_lock); 863 requeue =__aio_run_iocbs(ctx); 864 unuse_mm(ctx->mm); 865 spin_unlock_irq(&ctx->ctx_lock); 866 set_fs(oldfs); 867 /* 868 * we're in a worker thread already, don't use queue_delayed_work, 869 */ 870 if (requeue) 871 queue_work(aio_wq, &ctx->wq); 872 } 873 874 875 /* 876 * Called by kick_iocb to queue the kiocb for retry 877 * and if required activate the aio work queue to process 878 * it 879 */ 880 static void queue_kicked_iocb(struct kiocb *iocb) 881 { 882 struct kioctx *ctx = iocb->ki_ctx; 883 unsigned long flags; 884 int run = 0; 885 886 WARN_ON((!list_empty(&iocb->ki_wait.task_list))); 887 888 spin_lock_irqsave(&ctx->ctx_lock, flags); 889 run = __queue_kicked_iocb(iocb); 890 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 891 if (run) 892 aio_queue_work(ctx); 893 } 894 895 /* 896 * kick_iocb: 897 * Called typically from a wait queue callback context 898 * (aio_wake_function) to trigger a retry of the iocb. 899 * The retry is usually executed by aio workqueue 900 * threads (See aio_kick_handler). 901 */ 902 void fastcall kick_iocb(struct kiocb *iocb) 903 { 904 /* sync iocbs are easy: they can only ever be executing from a 905 * single context. */ 906 if (is_sync_kiocb(iocb)) { 907 kiocbSetKicked(iocb); 908 wake_up_process(iocb->ki_obj.tsk); 909 return; 910 } 911 912 /* If its already kicked we shouldn't queue it again */ 913 if (!kiocbTryKick(iocb)) { 914 queue_kicked_iocb(iocb); 915 } 916 } 917 EXPORT_SYMBOL(kick_iocb); 918 919 /* aio_complete 920 * Called when the io request on the given iocb is complete. 921 * Returns true if this is the last user of the request. The 922 * only other user of the request can be the cancellation code. 923 */ 924 int fastcall aio_complete(struct kiocb *iocb, long res, long res2) 925 { 926 struct kioctx *ctx = iocb->ki_ctx; 927 struct aio_ring_info *info; 928 struct aio_ring *ring; 929 struct io_event *event; 930 unsigned long flags; 931 unsigned long tail; 932 int ret; 933 934 /* Special case handling for sync iocbs: events go directly 935 * into the iocb for fast handling. Note that this will not 936 * work if we allow sync kiocbs to be cancelled. in which 937 * case the usage count checks will have to move under ctx_lock 938 * for all cases. 939 */ 940 if (is_sync_kiocb(iocb)) { 941 int ret; 942 943 iocb->ki_user_data = res; 944 if (iocb->ki_users == 1) { 945 iocb->ki_users = 0; 946 ret = 1; 947 } else { 948 spin_lock_irq(&ctx->ctx_lock); 949 iocb->ki_users--; 950 ret = (0 == iocb->ki_users); 951 spin_unlock_irq(&ctx->ctx_lock); 952 } 953 /* sync iocbs put the task here for us */ 954 wake_up_process(iocb->ki_obj.tsk); 955 return ret; 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 || (int)nr_events <= 0)) { 1266 pr_debug("EINVAL: io_setup: ctx or nr_events > max\n"); 1267 goto out; 1268 } 1269 1270 ioctx = ioctx_alloc(nr_events); 1271 ret = PTR_ERR(ioctx); 1272 if (!IS_ERR(ioctx)) { 1273 ret = put_user(ioctx->user_id, ctxp); 1274 if (!ret) 1275 return 0; 1276 1277 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ 1278 io_destroy(ioctx); 1279 } 1280 1281 out: 1282 return ret; 1283 } 1284 1285 /* sys_io_destroy: 1286 * Destroy the aio_context specified. May cancel any outstanding 1287 * AIOs and block on completion. Will fail with -ENOSYS if not 1288 * implemented. May fail with -EFAULT if the context pointed to 1289 * is invalid. 1290 */ 1291 asmlinkage long sys_io_destroy(aio_context_t ctx) 1292 { 1293 struct kioctx *ioctx = lookup_ioctx(ctx); 1294 if (likely(NULL != ioctx)) { 1295 io_destroy(ioctx); 1296 return 0; 1297 } 1298 pr_debug("EINVAL: io_destroy: invalid context id\n"); 1299 return -EINVAL; 1300 } 1301 1302 /* 1303 * Default retry method for aio_read (also used for first time submit) 1304 * Responsible for updating iocb state as retries progress 1305 */ 1306 static ssize_t aio_pread(struct kiocb *iocb) 1307 { 1308 struct file *file = iocb->ki_filp; 1309 struct address_space *mapping = file->f_mapping; 1310 struct inode *inode = mapping->host; 1311 ssize_t ret = 0; 1312 1313 ret = file->f_op->aio_read(iocb, iocb->ki_buf, 1314 iocb->ki_left, iocb->ki_pos); 1315 1316 /* 1317 * Can't just depend on iocb->ki_left to determine 1318 * whether we are done. This may have been a short read. 1319 */ 1320 if (ret > 0) { 1321 iocb->ki_buf += ret; 1322 iocb->ki_left -= ret; 1323 /* 1324 * For pipes and sockets we return once we have 1325 * some data; for regular files we retry till we 1326 * complete the entire read or find that we can't 1327 * read any more data (e.g short reads). 1328 */ 1329 if (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)) 1330 ret = -EIOCBRETRY; 1331 } 1332 1333 /* This means we must have transferred all that we could */ 1334 /* No need to retry anymore */ 1335 if ((ret == 0) || (iocb->ki_left == 0)) 1336 ret = iocb->ki_nbytes - iocb->ki_left; 1337 1338 return ret; 1339 } 1340 1341 /* 1342 * Default retry method for aio_write (also used for first time submit) 1343 * Responsible for updating iocb state as retries progress 1344 */ 1345 static ssize_t aio_pwrite(struct kiocb *iocb) 1346 { 1347 struct file *file = iocb->ki_filp; 1348 ssize_t ret = 0; 1349 1350 ret = file->f_op->aio_write(iocb, iocb->ki_buf, 1351 iocb->ki_left, iocb->ki_pos); 1352 1353 if (ret > 0) { 1354 iocb->ki_buf += ret; 1355 iocb->ki_left -= ret; 1356 1357 ret = -EIOCBRETRY; 1358 } 1359 1360 /* This means we must have transferred all that we could */ 1361 /* No need to retry anymore */ 1362 if ((ret == 0) || (iocb->ki_left == 0)) 1363 ret = iocb->ki_nbytes - iocb->ki_left; 1364 1365 return ret; 1366 } 1367 1368 static ssize_t aio_fdsync(struct kiocb *iocb) 1369 { 1370 struct file *file = iocb->ki_filp; 1371 ssize_t ret = -EINVAL; 1372 1373 if (file->f_op->aio_fsync) 1374 ret = file->f_op->aio_fsync(iocb, 1); 1375 return ret; 1376 } 1377 1378 static ssize_t aio_fsync(struct kiocb *iocb) 1379 { 1380 struct file *file = iocb->ki_filp; 1381 ssize_t ret = -EINVAL; 1382 1383 if (file->f_op->aio_fsync) 1384 ret = file->f_op->aio_fsync(iocb, 0); 1385 return ret; 1386 } 1387 1388 /* 1389 * aio_setup_iocb: 1390 * Performs the initial checks and aio retry method 1391 * setup for the kiocb at the time of io submission. 1392 */ 1393 static ssize_t aio_setup_iocb(struct kiocb *kiocb) 1394 { 1395 struct file *file = kiocb->ki_filp; 1396 ssize_t ret = 0; 1397 1398 switch (kiocb->ki_opcode) { 1399 case IOCB_CMD_PREAD: 1400 ret = -EBADF; 1401 if (unlikely(!(file->f_mode & FMODE_READ))) 1402 break; 1403 ret = -EFAULT; 1404 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, 1405 kiocb->ki_left))) 1406 break; 1407 ret = -EINVAL; 1408 if (file->f_op->aio_read) 1409 kiocb->ki_retry = aio_pread; 1410 break; 1411 case IOCB_CMD_PWRITE: 1412 ret = -EBADF; 1413 if (unlikely(!(file->f_mode & FMODE_WRITE))) 1414 break; 1415 ret = -EFAULT; 1416 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, 1417 kiocb->ki_left))) 1418 break; 1419 ret = -EINVAL; 1420 if (file->f_op->aio_write) 1421 kiocb->ki_retry = aio_pwrite; 1422 break; 1423 case IOCB_CMD_FDSYNC: 1424 ret = -EINVAL; 1425 if (file->f_op->aio_fsync) 1426 kiocb->ki_retry = aio_fdsync; 1427 break; 1428 case IOCB_CMD_FSYNC: 1429 ret = -EINVAL; 1430 if (file->f_op->aio_fsync) 1431 kiocb->ki_retry = aio_fsync; 1432 break; 1433 default: 1434 dprintk("EINVAL: io_submit: no operation provided\n"); 1435 ret = -EINVAL; 1436 } 1437 1438 if (!kiocb->ki_retry) 1439 return ret; 1440 1441 return 0; 1442 } 1443 1444 /* 1445 * aio_wake_function: 1446 * wait queue callback function for aio notification, 1447 * Simply triggers a retry of the operation via kick_iocb. 1448 * 1449 * This callback is specified in the wait queue entry in 1450 * a kiocb (current->io_wait points to this wait queue 1451 * entry when an aio operation executes; it is used 1452 * instead of a synchronous wait when an i/o blocking 1453 * condition is encountered during aio). 1454 * 1455 * Note: 1456 * This routine is executed with the wait queue lock held. 1457 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests 1458 * the ioctx lock inside the wait queue lock. This is safe 1459 * because this callback isn't used for wait queues which 1460 * are nested inside ioctx lock (i.e. ctx->wait) 1461 */ 1462 static int aio_wake_function(wait_queue_t *wait, unsigned mode, 1463 int sync, void *key) 1464 { 1465 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); 1466 1467 list_del_init(&wait->task_list); 1468 kick_iocb(iocb); 1469 return 1; 1470 } 1471 1472 int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1473 struct iocb *iocb) 1474 { 1475 struct kiocb *req; 1476 struct file *file; 1477 ssize_t ret; 1478 1479 /* enforce forwards compatibility on users */ 1480 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || 1481 iocb->aio_reserved3)) { 1482 pr_debug("EINVAL: io_submit: reserve field set\n"); 1483 return -EINVAL; 1484 } 1485 1486 /* prevent overflows */ 1487 if (unlikely( 1488 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1489 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1490 ((ssize_t)iocb->aio_nbytes < 0) 1491 )) { 1492 pr_debug("EINVAL: io_submit: overflow check\n"); 1493 return -EINVAL; 1494 } 1495 1496 file = fget(iocb->aio_fildes); 1497 if (unlikely(!file)) 1498 return -EBADF; 1499 1500 req = aio_get_req(ctx); /* returns with 2 references to req */ 1501 if (unlikely(!req)) { 1502 fput(file); 1503 return -EAGAIN; 1504 } 1505 1506 req->ki_filp = file; 1507 ret = put_user(req->ki_key, &user_iocb->aio_key); 1508 if (unlikely(ret)) { 1509 dprintk("EFAULT: aio_key\n"); 1510 goto out_put_req; 1511 } 1512 1513 req->ki_obj.user = user_iocb; 1514 req->ki_user_data = iocb->aio_data; 1515 req->ki_pos = iocb->aio_offset; 1516 1517 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; 1518 req->ki_left = req->ki_nbytes = iocb->aio_nbytes; 1519 req->ki_opcode = iocb->aio_lio_opcode; 1520 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); 1521 INIT_LIST_HEAD(&req->ki_wait.task_list); 1522 req->ki_retried = 0; 1523 1524 ret = aio_setup_iocb(req); 1525 1526 if (ret) 1527 goto out_put_req; 1528 1529 spin_lock_irq(&ctx->ctx_lock); 1530 if (likely(list_empty(&ctx->run_list))) { 1531 aio_run_iocb(req); 1532 } else { 1533 list_add_tail(&req->ki_run_list, &ctx->run_list); 1534 /* drain the run list */ 1535 while (__aio_run_iocbs(ctx)) 1536 ; 1537 } 1538 spin_unlock_irq(&ctx->ctx_lock); 1539 aio_put_req(req); /* drop extra ref to req */ 1540 return 0; 1541 1542 out_put_req: 1543 aio_put_req(req); /* drop extra ref to req */ 1544 aio_put_req(req); /* drop i/o ref to req */ 1545 return ret; 1546 } 1547 1548 /* sys_io_submit: 1549 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1550 * the number of iocbs queued. May return -EINVAL if the aio_context 1551 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1552 * *iocbpp[0] is not properly initialized, if the operation specified 1553 * is invalid for the file descriptor in the iocb. May fail with 1554 * -EFAULT if any of the data structures point to invalid data. May 1555 * fail with -EBADF if the file descriptor specified in the first 1556 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1557 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1558 * fail with -ENOSYS if not implemented. 1559 */ 1560 asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, 1561 struct iocb __user * __user *iocbpp) 1562 { 1563 struct kioctx *ctx; 1564 long ret = 0; 1565 int i; 1566 1567 if (unlikely(nr < 0)) 1568 return -EINVAL; 1569 1570 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1571 return -EFAULT; 1572 1573 ctx = lookup_ioctx(ctx_id); 1574 if (unlikely(!ctx)) { 1575 pr_debug("EINVAL: io_submit: invalid context id\n"); 1576 return -EINVAL; 1577 } 1578 1579 /* 1580 * AKPM: should this return a partial result if some of the IOs were 1581 * successfully submitted? 1582 */ 1583 for (i=0; i<nr; i++) { 1584 struct iocb __user *user_iocb; 1585 struct iocb tmp; 1586 1587 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1588 ret = -EFAULT; 1589 break; 1590 } 1591 1592 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1593 ret = -EFAULT; 1594 break; 1595 } 1596 1597 ret = io_submit_one(ctx, user_iocb, &tmp); 1598 if (ret) 1599 break; 1600 } 1601 1602 put_ioctx(ctx); 1603 return i ? i : ret; 1604 } 1605 1606 /* lookup_kiocb 1607 * Finds a given iocb for cancellation. 1608 * MUST be called with ctx->ctx_lock held. 1609 */ 1610 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 1611 u32 key) 1612 { 1613 struct list_head *pos; 1614 /* TODO: use a hash or array, this sucks. */ 1615 list_for_each(pos, &ctx->active_reqs) { 1616 struct kiocb *kiocb = list_kiocb(pos); 1617 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) 1618 return kiocb; 1619 } 1620 return NULL; 1621 } 1622 1623 /* sys_io_cancel: 1624 * Attempts to cancel an iocb previously passed to io_submit. If 1625 * the operation is successfully cancelled, the resulting event is 1626 * copied into the memory pointed to by result without being placed 1627 * into the completion queue and 0 is returned. May fail with 1628 * -EFAULT if any of the data structures pointed to are invalid. 1629 * May fail with -EINVAL if aio_context specified by ctx_id is 1630 * invalid. May fail with -EAGAIN if the iocb specified was not 1631 * cancelled. Will fail with -ENOSYS if not implemented. 1632 */ 1633 asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, 1634 struct io_event __user *result) 1635 { 1636 int (*cancel)(struct kiocb *iocb, struct io_event *res); 1637 struct kioctx *ctx; 1638 struct kiocb *kiocb; 1639 u32 key; 1640 int ret; 1641 1642 ret = get_user(key, &iocb->aio_key); 1643 if (unlikely(ret)) 1644 return -EFAULT; 1645 1646 ctx = lookup_ioctx(ctx_id); 1647 if (unlikely(!ctx)) 1648 return -EINVAL; 1649 1650 spin_lock_irq(&ctx->ctx_lock); 1651 ret = -EAGAIN; 1652 kiocb = lookup_kiocb(ctx, iocb, key); 1653 if (kiocb && kiocb->ki_cancel) { 1654 cancel = kiocb->ki_cancel; 1655 kiocb->ki_users ++; 1656 kiocbSetCancelled(kiocb); 1657 } else 1658 cancel = NULL; 1659 spin_unlock_irq(&ctx->ctx_lock); 1660 1661 if (NULL != cancel) { 1662 struct io_event tmp; 1663 pr_debug("calling cancel\n"); 1664 memset(&tmp, 0, sizeof(tmp)); 1665 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; 1666 tmp.data = kiocb->ki_user_data; 1667 ret = cancel(kiocb, &tmp); 1668 if (!ret) { 1669 /* Cancellation succeeded -- copy the result 1670 * into the user's buffer. 1671 */ 1672 if (copy_to_user(result, &tmp, sizeof(tmp))) 1673 ret = -EFAULT; 1674 } 1675 } else 1676 printk(KERN_DEBUG "iocb has no cancel operation\n"); 1677 1678 put_ioctx(ctx); 1679 1680 return ret; 1681 } 1682 1683 /* io_getevents: 1684 * Attempts to read at least min_nr events and up to nr events from 1685 * the completion queue for the aio_context specified by ctx_id. May 1686 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, 1687 * if nr is out of range, if when is out of range. May fail with 1688 * -EFAULT if any of the memory specified to is invalid. May return 1689 * 0 or < min_nr if no events are available and the timeout specified 1690 * by when has elapsed, where when == NULL specifies an infinite 1691 * timeout. Note that the timeout pointed to by when is relative and 1692 * will be updated if not NULL and the operation blocks. Will fail 1693 * with -ENOSYS if not implemented. 1694 */ 1695 asmlinkage long sys_io_getevents(aio_context_t ctx_id, 1696 long min_nr, 1697 long nr, 1698 struct io_event __user *events, 1699 struct timespec __user *timeout) 1700 { 1701 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1702 long ret = -EINVAL; 1703 1704 if (likely(ioctx)) { 1705 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) 1706 ret = read_events(ioctx, min_nr, nr, events, timeout); 1707 put_ioctx(ioctx); 1708 } 1709 1710 return ret; 1711 } 1712 1713 __initcall(aio_setup); 1714 1715 EXPORT_SYMBOL(aio_complete); 1716 EXPORT_SYMBOL(aio_put_req); 1717 EXPORT_SYMBOL(wait_on_sync_kiocb); 1718