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 activate_mm(active_mm, mm); 571 task_unlock(tsk); 572 573 mmdrop(active_mm); 574 } 575 576 /* 577 * unuse_mm 578 * Reverses the effect of use_mm, i.e. releases the 579 * specified mm context which was earlier taken on 580 * by the calling kernel thread 581 * (Note: this routine is intended to be called only 582 * from a kernel thread context) 583 * 584 * Comments: Called with ctx->ctx_lock held. This nests 585 * task_lock instead ctx_lock. 586 */ 587 static void unuse_mm(struct mm_struct *mm) 588 { 589 struct task_struct *tsk = current; 590 591 task_lock(tsk); 592 tsk->flags &= ~PF_BORROWED_MM; 593 tsk->mm = NULL; 594 /* active_mm is still 'mm' */ 595 enter_lazy_tlb(mm, tsk); 596 task_unlock(tsk); 597 } 598 599 /* 600 * Queue up a kiocb to be retried. Assumes that the kiocb 601 * has already been marked as kicked, and places it on 602 * the retry run list for the corresponding ioctx, if it 603 * isn't already queued. Returns 1 if it actually queued 604 * the kiocb (to tell the caller to activate the work 605 * queue to process it), or 0, if it found that it was 606 * already queued. 607 * 608 * Should be called with the spin lock iocb->ki_ctx->ctx_lock 609 * held 610 */ 611 static inline int __queue_kicked_iocb(struct kiocb *iocb) 612 { 613 struct kioctx *ctx = iocb->ki_ctx; 614 615 if (list_empty(&iocb->ki_run_list)) { 616 list_add_tail(&iocb->ki_run_list, 617 &ctx->run_list); 618 return 1; 619 } 620 return 0; 621 } 622 623 /* aio_run_iocb 624 * This is the core aio execution routine. It is 625 * invoked both for initial i/o submission and 626 * subsequent retries via the aio_kick_handler. 627 * Expects to be invoked with iocb->ki_ctx->lock 628 * already held. The lock is released and reaquired 629 * as needed during processing. 630 * 631 * Calls the iocb retry method (already setup for the 632 * iocb on initial submission) for operation specific 633 * handling, but takes care of most of common retry 634 * execution details for a given iocb. The retry method 635 * needs to be non-blocking as far as possible, to avoid 636 * holding up other iocbs waiting to be serviced by the 637 * retry kernel thread. 638 * 639 * The trickier parts in this code have to do with 640 * ensuring that only one retry instance is in progress 641 * for a given iocb at any time. Providing that guarantee 642 * simplifies the coding of individual aio operations as 643 * it avoids various potential races. 644 */ 645 static ssize_t aio_run_iocb(struct kiocb *iocb) 646 { 647 struct kioctx *ctx = iocb->ki_ctx; 648 ssize_t (*retry)(struct kiocb *); 649 ssize_t ret; 650 651 if (iocb->ki_retried++ > 1024*1024) { 652 printk("Maximal retry count. Bytes done %Zd\n", 653 iocb->ki_nbytes - iocb->ki_left); 654 return -EAGAIN; 655 } 656 657 if (!(iocb->ki_retried & 0xff)) { 658 pr_debug("%ld retry: %d of %d\n", iocb->ki_retried, 659 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); 660 } 661 662 if (!(retry = iocb->ki_retry)) { 663 printk("aio_run_iocb: iocb->ki_retry = NULL\n"); 664 return 0; 665 } 666 667 /* 668 * We don't want the next retry iteration for this 669 * operation to start until this one has returned and 670 * updated the iocb state. However, wait_queue functions 671 * can trigger a kick_iocb from interrupt context in the 672 * meantime, indicating that data is available for the next 673 * iteration. We want to remember that and enable the 674 * next retry iteration _after_ we are through with 675 * this one. 676 * 677 * So, in order to be able to register a "kick", but 678 * prevent it from being queued now, we clear the kick 679 * flag, but make the kick code *think* that the iocb is 680 * still on the run list until we are actually done. 681 * When we are done with this iteration, we check if 682 * the iocb was kicked in the meantime and if so, queue 683 * it up afresh. 684 */ 685 686 kiocbClearKicked(iocb); 687 688 /* 689 * This is so that aio_complete knows it doesn't need to 690 * pull the iocb off the run list (We can't just call 691 * INIT_LIST_HEAD because we don't want a kick_iocb to 692 * queue this on the run list yet) 693 */ 694 iocb->ki_run_list.next = iocb->ki_run_list.prev = NULL; 695 spin_unlock_irq(&ctx->ctx_lock); 696 697 /* Quit retrying if the i/o has been cancelled */ 698 if (kiocbIsCancelled(iocb)) { 699 ret = -EINTR; 700 aio_complete(iocb, ret, 0); 701 /* must not access the iocb after this */ 702 goto out; 703 } 704 705 /* 706 * Now we are all set to call the retry method in async 707 * context. By setting this thread's io_wait context 708 * to point to the wait queue entry inside the currently 709 * running iocb for the duration of the retry, we ensure 710 * that async notification wakeups are queued by the 711 * operation instead of blocking waits, and when notified, 712 * cause the iocb to be kicked for continuation (through 713 * the aio_wake_function callback). 714 */ 715 BUG_ON(current->io_wait != NULL); 716 current->io_wait = &iocb->ki_wait; 717 ret = retry(iocb); 718 current->io_wait = NULL; 719 720 if (-EIOCBRETRY != ret) { 721 if (-EIOCBQUEUED != ret) { 722 BUG_ON(!list_empty(&iocb->ki_wait.task_list)); 723 aio_complete(iocb, ret, 0); 724 /* must not access the iocb after this */ 725 } 726 } else { 727 /* 728 * Issue an additional retry to avoid waiting forever if 729 * no waits were queued (e.g. in case of a short read). 730 */ 731 if (list_empty(&iocb->ki_wait.task_list)) 732 kiocbSetKicked(iocb); 733 } 734 out: 735 spin_lock_irq(&ctx->ctx_lock); 736 737 if (-EIOCBRETRY == ret) { 738 /* 739 * OK, now that we are done with this iteration 740 * and know that there is more left to go, 741 * this is where we let go so that a subsequent 742 * "kick" can start the next iteration 743 */ 744 745 /* will make __queue_kicked_iocb succeed from here on */ 746 INIT_LIST_HEAD(&iocb->ki_run_list); 747 /* we must queue the next iteration ourselves, if it 748 * has already been kicked */ 749 if (kiocbIsKicked(iocb)) { 750 __queue_kicked_iocb(iocb); 751 752 /* 753 * __queue_kicked_iocb will always return 1 here, because 754 * iocb->ki_run_list is empty at this point so it should 755 * be safe to unconditionally queue the context into the 756 * work queue. 757 */ 758 aio_queue_work(ctx); 759 } 760 } 761 return ret; 762 } 763 764 /* 765 * __aio_run_iocbs: 766 * Process all pending retries queued on the ioctx 767 * run list. 768 * Assumes it is operating within the aio issuer's mm 769 * context. Expects to be called with ctx->ctx_lock held 770 */ 771 static int __aio_run_iocbs(struct kioctx *ctx) 772 { 773 struct kiocb *iocb; 774 LIST_HEAD(run_list); 775 776 list_splice_init(&ctx->run_list, &run_list); 777 while (!list_empty(&run_list)) { 778 iocb = list_entry(run_list.next, struct kiocb, 779 ki_run_list); 780 list_del(&iocb->ki_run_list); 781 /* 782 * Hold an extra reference while retrying i/o. 783 */ 784 iocb->ki_users++; /* grab extra reference */ 785 aio_run_iocb(iocb); 786 if (__aio_put_req(ctx, iocb)) /* drop extra ref */ 787 put_ioctx(ctx); 788 } 789 if (!list_empty(&ctx->run_list)) 790 return 1; 791 return 0; 792 } 793 794 static void aio_queue_work(struct kioctx * ctx) 795 { 796 unsigned long timeout; 797 /* 798 * if someone is waiting, get the work started right 799 * away, otherwise, use a longer delay 800 */ 801 smp_mb(); 802 if (waitqueue_active(&ctx->wait)) 803 timeout = 1; 804 else 805 timeout = HZ/10; 806 queue_delayed_work(aio_wq, &ctx->wq, timeout); 807 } 808 809 810 /* 811 * aio_run_iocbs: 812 * Process all pending retries queued on the ioctx 813 * run list. 814 * Assumes it is operating within the aio issuer's mm 815 * context. 816 */ 817 static inline void aio_run_iocbs(struct kioctx *ctx) 818 { 819 int requeue; 820 821 spin_lock_irq(&ctx->ctx_lock); 822 823 requeue = __aio_run_iocbs(ctx); 824 spin_unlock_irq(&ctx->ctx_lock); 825 if (requeue) 826 aio_queue_work(ctx); 827 } 828 829 /* 830 * just like aio_run_iocbs, but keeps running them until 831 * the list stays empty 832 */ 833 static inline void aio_run_all_iocbs(struct kioctx *ctx) 834 { 835 spin_lock_irq(&ctx->ctx_lock); 836 while (__aio_run_iocbs(ctx)) 837 ; 838 spin_unlock_irq(&ctx->ctx_lock); 839 } 840 841 /* 842 * aio_kick_handler: 843 * Work queue handler triggered to process pending 844 * retries on an ioctx. Takes on the aio issuer's 845 * mm context before running the iocbs, so that 846 * copy_xxx_user operates on the issuer's address 847 * space. 848 * Run on aiod's context. 849 */ 850 static void aio_kick_handler(void *data) 851 { 852 struct kioctx *ctx = data; 853 mm_segment_t oldfs = get_fs(); 854 int requeue; 855 856 set_fs(USER_DS); 857 use_mm(ctx->mm); 858 spin_lock_irq(&ctx->ctx_lock); 859 requeue =__aio_run_iocbs(ctx); 860 unuse_mm(ctx->mm); 861 spin_unlock_irq(&ctx->ctx_lock); 862 set_fs(oldfs); 863 /* 864 * we're in a worker thread already, don't use queue_delayed_work, 865 */ 866 if (requeue) 867 queue_work(aio_wq, &ctx->wq); 868 } 869 870 871 /* 872 * Called by kick_iocb to queue the kiocb for retry 873 * and if required activate the aio work queue to process 874 * it 875 */ 876 static void queue_kicked_iocb(struct kiocb *iocb) 877 { 878 struct kioctx *ctx = iocb->ki_ctx; 879 unsigned long flags; 880 int run = 0; 881 882 WARN_ON((!list_empty(&iocb->ki_wait.task_list))); 883 884 spin_lock_irqsave(&ctx->ctx_lock, flags); 885 run = __queue_kicked_iocb(iocb); 886 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 887 if (run) 888 aio_queue_work(ctx); 889 } 890 891 /* 892 * kick_iocb: 893 * Called typically from a wait queue callback context 894 * (aio_wake_function) to trigger a retry of the iocb. 895 * The retry is usually executed by aio workqueue 896 * threads (See aio_kick_handler). 897 */ 898 void fastcall kick_iocb(struct kiocb *iocb) 899 { 900 /* sync iocbs are easy: they can only ever be executing from a 901 * single context. */ 902 if (is_sync_kiocb(iocb)) { 903 kiocbSetKicked(iocb); 904 wake_up_process(iocb->ki_obj.tsk); 905 return; 906 } 907 908 /* If its already kicked we shouldn't queue it again */ 909 if (!kiocbTryKick(iocb)) { 910 queue_kicked_iocb(iocb); 911 } 912 } 913 EXPORT_SYMBOL(kick_iocb); 914 915 /* aio_complete 916 * Called when the io request on the given iocb is complete. 917 * Returns true if this is the last user of the request. The 918 * only other user of the request can be the cancellation code. 919 */ 920 int fastcall aio_complete(struct kiocb *iocb, long res, long res2) 921 { 922 struct kioctx *ctx = iocb->ki_ctx; 923 struct aio_ring_info *info; 924 struct aio_ring *ring; 925 struct io_event *event; 926 unsigned long flags; 927 unsigned long tail; 928 int ret; 929 930 /* Special case handling for sync iocbs: events go directly 931 * into the iocb for fast handling. Note that this will not 932 * work if we allow sync kiocbs to be cancelled. in which 933 * case the usage count checks will have to move under ctx_lock 934 * for all cases. 935 */ 936 if (is_sync_kiocb(iocb)) { 937 int ret; 938 939 iocb->ki_user_data = res; 940 if (iocb->ki_users == 1) { 941 iocb->ki_users = 0; 942 ret = 1; 943 } else { 944 spin_lock_irq(&ctx->ctx_lock); 945 iocb->ki_users--; 946 ret = (0 == iocb->ki_users); 947 spin_unlock_irq(&ctx->ctx_lock); 948 } 949 /* sync iocbs put the task here for us */ 950 wake_up_process(iocb->ki_obj.tsk); 951 return ret; 952 } 953 954 info = &ctx->ring_info; 955 956 /* add a completion event to the ring buffer. 957 * must be done holding ctx->ctx_lock to prevent 958 * other code from messing with the tail 959 * pointer since we might be called from irq 960 * context. 961 */ 962 spin_lock_irqsave(&ctx->ctx_lock, flags); 963 964 if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list)) 965 list_del_init(&iocb->ki_run_list); 966 967 /* 968 * cancelled requests don't get events, userland was given one 969 * when the event got cancelled. 970 */ 971 if (kiocbIsCancelled(iocb)) 972 goto put_rq; 973 974 ring = kmap_atomic(info->ring_pages[0], KM_IRQ1); 975 976 tail = info->tail; 977 event = aio_ring_event(info, tail, KM_IRQ0); 978 if (++tail >= info->nr) 979 tail = 0; 980 981 event->obj = (u64)(unsigned long)iocb->ki_obj.user; 982 event->data = iocb->ki_user_data; 983 event->res = res; 984 event->res2 = res2; 985 986 dprintk("aio_complete: %p[%lu]: %p: %p %Lx %lx %lx\n", 987 ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, 988 res, res2); 989 990 /* after flagging the request as done, we 991 * must never even look at it again 992 */ 993 smp_wmb(); /* make event visible before updating tail */ 994 995 info->tail = tail; 996 ring->tail = tail; 997 998 put_aio_ring_event(event, KM_IRQ0); 999 kunmap_atomic(ring, KM_IRQ1); 1000 1001 pr_debug("added to ring %p at [%lu]\n", iocb, tail); 1002 1003 pr_debug("%ld retries: %d of %d\n", iocb->ki_retried, 1004 iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes); 1005 put_rq: 1006 /* everything turned out well, dispose of the aiocb. */ 1007 ret = __aio_put_req(ctx, iocb); 1008 1009 spin_unlock_irqrestore(&ctx->ctx_lock, flags); 1010 1011 if (waitqueue_active(&ctx->wait)) 1012 wake_up(&ctx->wait); 1013 1014 if (ret) 1015 put_ioctx(ctx); 1016 1017 return ret; 1018 } 1019 1020 /* aio_read_evt 1021 * Pull an event off of the ioctx's event ring. Returns the number of 1022 * events fetched (0 or 1 ;-) 1023 * FIXME: make this use cmpxchg. 1024 * TODO: make the ringbuffer user mmap()able (requires FIXME). 1025 */ 1026 static int aio_read_evt(struct kioctx *ioctx, struct io_event *ent) 1027 { 1028 struct aio_ring_info *info = &ioctx->ring_info; 1029 struct aio_ring *ring; 1030 unsigned long head; 1031 int ret = 0; 1032 1033 ring = kmap_atomic(info->ring_pages[0], KM_USER0); 1034 dprintk("in aio_read_evt h%lu t%lu m%lu\n", 1035 (unsigned long)ring->head, (unsigned long)ring->tail, 1036 (unsigned long)ring->nr); 1037 1038 if (ring->head == ring->tail) 1039 goto out; 1040 1041 spin_lock(&info->ring_lock); 1042 1043 head = ring->head % info->nr; 1044 if (head != ring->tail) { 1045 struct io_event *evp = aio_ring_event(info, head, KM_USER1); 1046 *ent = *evp; 1047 head = (head + 1) % info->nr; 1048 smp_mb(); /* finish reading the event before updatng the head */ 1049 ring->head = head; 1050 ret = 1; 1051 put_aio_ring_event(evp, KM_USER1); 1052 } 1053 spin_unlock(&info->ring_lock); 1054 1055 out: 1056 kunmap_atomic(ring, KM_USER0); 1057 dprintk("leaving aio_read_evt: %d h%lu t%lu\n", ret, 1058 (unsigned long)ring->head, (unsigned long)ring->tail); 1059 return ret; 1060 } 1061 1062 struct aio_timeout { 1063 struct timer_list timer; 1064 int timed_out; 1065 struct task_struct *p; 1066 }; 1067 1068 static void timeout_func(unsigned long data) 1069 { 1070 struct aio_timeout *to = (struct aio_timeout *)data; 1071 1072 to->timed_out = 1; 1073 wake_up_process(to->p); 1074 } 1075 1076 static inline void init_timeout(struct aio_timeout *to) 1077 { 1078 init_timer(&to->timer); 1079 to->timer.data = (unsigned long)to; 1080 to->timer.function = timeout_func; 1081 to->timed_out = 0; 1082 to->p = current; 1083 } 1084 1085 static inline void set_timeout(long start_jiffies, struct aio_timeout *to, 1086 const struct timespec *ts) 1087 { 1088 to->timer.expires = start_jiffies + timespec_to_jiffies(ts); 1089 if (time_after(to->timer.expires, jiffies)) 1090 add_timer(&to->timer); 1091 else 1092 to->timed_out = 1; 1093 } 1094 1095 static inline void clear_timeout(struct aio_timeout *to) 1096 { 1097 del_singleshot_timer_sync(&to->timer); 1098 } 1099 1100 static int read_events(struct kioctx *ctx, 1101 long min_nr, long nr, 1102 struct io_event __user *event, 1103 struct timespec __user *timeout) 1104 { 1105 long start_jiffies = jiffies; 1106 struct task_struct *tsk = current; 1107 DECLARE_WAITQUEUE(wait, tsk); 1108 int ret; 1109 int i = 0; 1110 struct io_event ent; 1111 struct aio_timeout to; 1112 int retry = 0; 1113 1114 /* needed to zero any padding within an entry (there shouldn't be 1115 * any, but C is fun! 1116 */ 1117 memset(&ent, 0, sizeof(ent)); 1118 retry: 1119 ret = 0; 1120 while (likely(i < nr)) { 1121 ret = aio_read_evt(ctx, &ent); 1122 if (unlikely(ret <= 0)) 1123 break; 1124 1125 dprintk("read event: %Lx %Lx %Lx %Lx\n", 1126 ent.data, ent.obj, ent.res, ent.res2); 1127 1128 /* Could we split the check in two? */ 1129 ret = -EFAULT; 1130 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1131 dprintk("aio: lost an event due to EFAULT.\n"); 1132 break; 1133 } 1134 ret = 0; 1135 1136 /* Good, event copied to userland, update counts. */ 1137 event ++; 1138 i ++; 1139 } 1140 1141 if (min_nr <= i) 1142 return i; 1143 if (ret) 1144 return ret; 1145 1146 /* End fast path */ 1147 1148 /* racey check, but it gets redone */ 1149 if (!retry && unlikely(!list_empty(&ctx->run_list))) { 1150 retry = 1; 1151 aio_run_all_iocbs(ctx); 1152 goto retry; 1153 } 1154 1155 init_timeout(&to); 1156 if (timeout) { 1157 struct timespec ts; 1158 ret = -EFAULT; 1159 if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) 1160 goto out; 1161 1162 set_timeout(start_jiffies, &to, &ts); 1163 } 1164 1165 while (likely(i < nr)) { 1166 add_wait_queue_exclusive(&ctx->wait, &wait); 1167 do { 1168 set_task_state(tsk, TASK_INTERRUPTIBLE); 1169 ret = aio_read_evt(ctx, &ent); 1170 if (ret) 1171 break; 1172 if (min_nr <= i) 1173 break; 1174 ret = 0; 1175 if (to.timed_out) /* Only check after read evt */ 1176 break; 1177 schedule(); 1178 if (signal_pending(tsk)) { 1179 ret = -EINTR; 1180 break; 1181 } 1182 /*ret = aio_read_evt(ctx, &ent);*/ 1183 } while (1) ; 1184 1185 set_task_state(tsk, TASK_RUNNING); 1186 remove_wait_queue(&ctx->wait, &wait); 1187 1188 if (unlikely(ret <= 0)) 1189 break; 1190 1191 ret = -EFAULT; 1192 if (unlikely(copy_to_user(event, &ent, sizeof(ent)))) { 1193 dprintk("aio: lost an event due to EFAULT.\n"); 1194 break; 1195 } 1196 1197 /* Good, event copied to userland, update counts. */ 1198 event ++; 1199 i ++; 1200 } 1201 1202 if (timeout) 1203 clear_timeout(&to); 1204 out: 1205 return i ? i : ret; 1206 } 1207 1208 /* Take an ioctx and remove it from the list of ioctx's. Protects 1209 * against races with itself via ->dead. 1210 */ 1211 static void io_destroy(struct kioctx *ioctx) 1212 { 1213 struct mm_struct *mm = current->mm; 1214 struct kioctx **tmp; 1215 int was_dead; 1216 1217 /* delete the entry from the list is someone else hasn't already */ 1218 write_lock(&mm->ioctx_list_lock); 1219 was_dead = ioctx->dead; 1220 ioctx->dead = 1; 1221 for (tmp = &mm->ioctx_list; *tmp && *tmp != ioctx; 1222 tmp = &(*tmp)->next) 1223 ; 1224 if (*tmp) 1225 *tmp = ioctx->next; 1226 write_unlock(&mm->ioctx_list_lock); 1227 1228 dprintk("aio_release(%p)\n", ioctx); 1229 if (likely(!was_dead)) 1230 put_ioctx(ioctx); /* twice for the list */ 1231 1232 aio_cancel_all(ioctx); 1233 wait_for_all_aios(ioctx); 1234 put_ioctx(ioctx); /* once for the lookup */ 1235 } 1236 1237 /* sys_io_setup: 1238 * Create an aio_context capable of receiving at least nr_events. 1239 * ctxp must not point to an aio_context that already exists, and 1240 * must be initialized to 0 prior to the call. On successful 1241 * creation of the aio_context, *ctxp is filled in with the resulting 1242 * handle. May fail with -EINVAL if *ctxp is not initialized, 1243 * if the specified nr_events exceeds internal limits. May fail 1244 * with -EAGAIN if the specified nr_events exceeds the user's limit 1245 * of available events. May fail with -ENOMEM if insufficient kernel 1246 * resources are available. May fail with -EFAULT if an invalid 1247 * pointer is passed for ctxp. Will fail with -ENOSYS if not 1248 * implemented. 1249 */ 1250 asmlinkage long sys_io_setup(unsigned nr_events, aio_context_t __user *ctxp) 1251 { 1252 struct kioctx *ioctx = NULL; 1253 unsigned long ctx; 1254 long ret; 1255 1256 ret = get_user(ctx, ctxp); 1257 if (unlikely(ret)) 1258 goto out; 1259 1260 ret = -EINVAL; 1261 if (unlikely(ctx || (int)nr_events <= 0)) { 1262 pr_debug("EINVAL: io_setup: ctx or nr_events > max\n"); 1263 goto out; 1264 } 1265 1266 ioctx = ioctx_alloc(nr_events); 1267 ret = PTR_ERR(ioctx); 1268 if (!IS_ERR(ioctx)) { 1269 ret = put_user(ioctx->user_id, ctxp); 1270 if (!ret) 1271 return 0; 1272 1273 get_ioctx(ioctx); /* io_destroy() expects us to hold a ref */ 1274 io_destroy(ioctx); 1275 } 1276 1277 out: 1278 return ret; 1279 } 1280 1281 /* sys_io_destroy: 1282 * Destroy the aio_context specified. May cancel any outstanding 1283 * AIOs and block on completion. Will fail with -ENOSYS if not 1284 * implemented. May fail with -EFAULT if the context pointed to 1285 * is invalid. 1286 */ 1287 asmlinkage long sys_io_destroy(aio_context_t ctx) 1288 { 1289 struct kioctx *ioctx = lookup_ioctx(ctx); 1290 if (likely(NULL != ioctx)) { 1291 io_destroy(ioctx); 1292 return 0; 1293 } 1294 pr_debug("EINVAL: io_destroy: invalid context id\n"); 1295 return -EINVAL; 1296 } 1297 1298 /* 1299 * Default retry method for aio_read (also used for first time submit) 1300 * Responsible for updating iocb state as retries progress 1301 */ 1302 static ssize_t aio_pread(struct kiocb *iocb) 1303 { 1304 struct file *file = iocb->ki_filp; 1305 struct address_space *mapping = file->f_mapping; 1306 struct inode *inode = mapping->host; 1307 ssize_t ret = 0; 1308 1309 ret = file->f_op->aio_read(iocb, iocb->ki_buf, 1310 iocb->ki_left, iocb->ki_pos); 1311 1312 /* 1313 * Can't just depend on iocb->ki_left to determine 1314 * whether we are done. This may have been a short read. 1315 */ 1316 if (ret > 0) { 1317 iocb->ki_buf += ret; 1318 iocb->ki_left -= ret; 1319 /* 1320 * For pipes and sockets we return once we have 1321 * some data; for regular files we retry till we 1322 * complete the entire read or find that we can't 1323 * read any more data (e.g short reads). 1324 */ 1325 if (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)) 1326 ret = -EIOCBRETRY; 1327 } 1328 1329 /* This means we must have transferred all that we could */ 1330 /* No need to retry anymore */ 1331 if ((ret == 0) || (iocb->ki_left == 0)) 1332 ret = iocb->ki_nbytes - iocb->ki_left; 1333 1334 return ret; 1335 } 1336 1337 /* 1338 * Default retry method for aio_write (also used for first time submit) 1339 * Responsible for updating iocb state as retries progress 1340 */ 1341 static ssize_t aio_pwrite(struct kiocb *iocb) 1342 { 1343 struct file *file = iocb->ki_filp; 1344 ssize_t ret = 0; 1345 1346 ret = file->f_op->aio_write(iocb, iocb->ki_buf, 1347 iocb->ki_left, iocb->ki_pos); 1348 1349 if (ret > 0) { 1350 iocb->ki_buf += ret; 1351 iocb->ki_left -= ret; 1352 1353 ret = -EIOCBRETRY; 1354 } 1355 1356 /* This means we must have transferred all that we could */ 1357 /* No need to retry anymore */ 1358 if ((ret == 0) || (iocb->ki_left == 0)) 1359 ret = iocb->ki_nbytes - iocb->ki_left; 1360 1361 return ret; 1362 } 1363 1364 static ssize_t aio_fdsync(struct kiocb *iocb) 1365 { 1366 struct file *file = iocb->ki_filp; 1367 ssize_t ret = -EINVAL; 1368 1369 if (file->f_op->aio_fsync) 1370 ret = file->f_op->aio_fsync(iocb, 1); 1371 return ret; 1372 } 1373 1374 static ssize_t aio_fsync(struct kiocb *iocb) 1375 { 1376 struct file *file = iocb->ki_filp; 1377 ssize_t ret = -EINVAL; 1378 1379 if (file->f_op->aio_fsync) 1380 ret = file->f_op->aio_fsync(iocb, 0); 1381 return ret; 1382 } 1383 1384 /* 1385 * aio_setup_iocb: 1386 * Performs the initial checks and aio retry method 1387 * setup for the kiocb at the time of io submission. 1388 */ 1389 static ssize_t aio_setup_iocb(struct kiocb *kiocb) 1390 { 1391 struct file *file = kiocb->ki_filp; 1392 ssize_t ret = 0; 1393 1394 switch (kiocb->ki_opcode) { 1395 case IOCB_CMD_PREAD: 1396 ret = -EBADF; 1397 if (unlikely(!(file->f_mode & FMODE_READ))) 1398 break; 1399 ret = -EFAULT; 1400 if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, 1401 kiocb->ki_left))) 1402 break; 1403 ret = -EINVAL; 1404 if (file->f_op->aio_read) 1405 kiocb->ki_retry = aio_pread; 1406 break; 1407 case IOCB_CMD_PWRITE: 1408 ret = -EBADF; 1409 if (unlikely(!(file->f_mode & FMODE_WRITE))) 1410 break; 1411 ret = -EFAULT; 1412 if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, 1413 kiocb->ki_left))) 1414 break; 1415 ret = -EINVAL; 1416 if (file->f_op->aio_write) 1417 kiocb->ki_retry = aio_pwrite; 1418 break; 1419 case IOCB_CMD_FDSYNC: 1420 ret = -EINVAL; 1421 if (file->f_op->aio_fsync) 1422 kiocb->ki_retry = aio_fdsync; 1423 break; 1424 case IOCB_CMD_FSYNC: 1425 ret = -EINVAL; 1426 if (file->f_op->aio_fsync) 1427 kiocb->ki_retry = aio_fsync; 1428 break; 1429 default: 1430 dprintk("EINVAL: io_submit: no operation provided\n"); 1431 ret = -EINVAL; 1432 } 1433 1434 if (!kiocb->ki_retry) 1435 return ret; 1436 1437 return 0; 1438 } 1439 1440 /* 1441 * aio_wake_function: 1442 * wait queue callback function for aio notification, 1443 * Simply triggers a retry of the operation via kick_iocb. 1444 * 1445 * This callback is specified in the wait queue entry in 1446 * a kiocb (current->io_wait points to this wait queue 1447 * entry when an aio operation executes; it is used 1448 * instead of a synchronous wait when an i/o blocking 1449 * condition is encountered during aio). 1450 * 1451 * Note: 1452 * This routine is executed with the wait queue lock held. 1453 * Since kick_iocb acquires iocb->ctx->ctx_lock, it nests 1454 * the ioctx lock inside the wait queue lock. This is safe 1455 * because this callback isn't used for wait queues which 1456 * are nested inside ioctx lock (i.e. ctx->wait) 1457 */ 1458 static int aio_wake_function(wait_queue_t *wait, unsigned mode, 1459 int sync, void *key) 1460 { 1461 struct kiocb *iocb = container_of(wait, struct kiocb, ki_wait); 1462 1463 list_del_init(&wait->task_list); 1464 kick_iocb(iocb); 1465 return 1; 1466 } 1467 1468 int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, 1469 struct iocb *iocb) 1470 { 1471 struct kiocb *req; 1472 struct file *file; 1473 ssize_t ret; 1474 1475 /* enforce forwards compatibility on users */ 1476 if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2 || 1477 iocb->aio_reserved3)) { 1478 pr_debug("EINVAL: io_submit: reserve field set\n"); 1479 return -EINVAL; 1480 } 1481 1482 /* prevent overflows */ 1483 if (unlikely( 1484 (iocb->aio_buf != (unsigned long)iocb->aio_buf) || 1485 (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || 1486 ((ssize_t)iocb->aio_nbytes < 0) 1487 )) { 1488 pr_debug("EINVAL: io_submit: overflow check\n"); 1489 return -EINVAL; 1490 } 1491 1492 file = fget(iocb->aio_fildes); 1493 if (unlikely(!file)) 1494 return -EBADF; 1495 1496 req = aio_get_req(ctx); /* returns with 2 references to req */ 1497 if (unlikely(!req)) { 1498 fput(file); 1499 return -EAGAIN; 1500 } 1501 1502 req->ki_filp = file; 1503 ret = put_user(req->ki_key, &user_iocb->aio_key); 1504 if (unlikely(ret)) { 1505 dprintk("EFAULT: aio_key\n"); 1506 goto out_put_req; 1507 } 1508 1509 req->ki_obj.user = user_iocb; 1510 req->ki_user_data = iocb->aio_data; 1511 req->ki_pos = iocb->aio_offset; 1512 1513 req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; 1514 req->ki_left = req->ki_nbytes = iocb->aio_nbytes; 1515 req->ki_opcode = iocb->aio_lio_opcode; 1516 init_waitqueue_func_entry(&req->ki_wait, aio_wake_function); 1517 INIT_LIST_HEAD(&req->ki_wait.task_list); 1518 req->ki_retried = 0; 1519 1520 ret = aio_setup_iocb(req); 1521 1522 if (ret) 1523 goto out_put_req; 1524 1525 spin_lock_irq(&ctx->ctx_lock); 1526 if (likely(list_empty(&ctx->run_list))) { 1527 aio_run_iocb(req); 1528 } else { 1529 list_add_tail(&req->ki_run_list, &ctx->run_list); 1530 /* drain the run list */ 1531 while (__aio_run_iocbs(ctx)) 1532 ; 1533 } 1534 spin_unlock_irq(&ctx->ctx_lock); 1535 aio_put_req(req); /* drop extra ref to req */ 1536 return 0; 1537 1538 out_put_req: 1539 aio_put_req(req); /* drop extra ref to req */ 1540 aio_put_req(req); /* drop i/o ref to req */ 1541 return ret; 1542 } 1543 1544 /* sys_io_submit: 1545 * Queue the nr iocbs pointed to by iocbpp for processing. Returns 1546 * the number of iocbs queued. May return -EINVAL if the aio_context 1547 * specified by ctx_id is invalid, if nr is < 0, if the iocb at 1548 * *iocbpp[0] is not properly initialized, if the operation specified 1549 * is invalid for the file descriptor in the iocb. May fail with 1550 * -EFAULT if any of the data structures point to invalid data. May 1551 * fail with -EBADF if the file descriptor specified in the first 1552 * iocb is invalid. May fail with -EAGAIN if insufficient resources 1553 * are available to queue any iocbs. Will return 0 if nr is 0. Will 1554 * fail with -ENOSYS if not implemented. 1555 */ 1556 asmlinkage long sys_io_submit(aio_context_t ctx_id, long nr, 1557 struct iocb __user * __user *iocbpp) 1558 { 1559 struct kioctx *ctx; 1560 long ret = 0; 1561 int i; 1562 1563 if (unlikely(nr < 0)) 1564 return -EINVAL; 1565 1566 if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) 1567 return -EFAULT; 1568 1569 ctx = lookup_ioctx(ctx_id); 1570 if (unlikely(!ctx)) { 1571 pr_debug("EINVAL: io_submit: invalid context id\n"); 1572 return -EINVAL; 1573 } 1574 1575 /* 1576 * AKPM: should this return a partial result if some of the IOs were 1577 * successfully submitted? 1578 */ 1579 for (i=0; i<nr; i++) { 1580 struct iocb __user *user_iocb; 1581 struct iocb tmp; 1582 1583 if (unlikely(__get_user(user_iocb, iocbpp + i))) { 1584 ret = -EFAULT; 1585 break; 1586 } 1587 1588 if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { 1589 ret = -EFAULT; 1590 break; 1591 } 1592 1593 ret = io_submit_one(ctx, user_iocb, &tmp); 1594 if (ret) 1595 break; 1596 } 1597 1598 put_ioctx(ctx); 1599 return i ? i : ret; 1600 } 1601 1602 /* lookup_kiocb 1603 * Finds a given iocb for cancellation. 1604 * MUST be called with ctx->ctx_lock held. 1605 */ 1606 static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 1607 u32 key) 1608 { 1609 struct list_head *pos; 1610 /* TODO: use a hash or array, this sucks. */ 1611 list_for_each(pos, &ctx->active_reqs) { 1612 struct kiocb *kiocb = list_kiocb(pos); 1613 if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) 1614 return kiocb; 1615 } 1616 return NULL; 1617 } 1618 1619 /* sys_io_cancel: 1620 * Attempts to cancel an iocb previously passed to io_submit. If 1621 * the operation is successfully cancelled, the resulting event is 1622 * copied into the memory pointed to by result without being placed 1623 * into the completion queue and 0 is returned. May fail with 1624 * -EFAULT if any of the data structures pointed to are invalid. 1625 * May fail with -EINVAL if aio_context specified by ctx_id is 1626 * invalid. May fail with -EAGAIN if the iocb specified was not 1627 * cancelled. Will fail with -ENOSYS if not implemented. 1628 */ 1629 asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb, 1630 struct io_event __user *result) 1631 { 1632 int (*cancel)(struct kiocb *iocb, struct io_event *res); 1633 struct kioctx *ctx; 1634 struct kiocb *kiocb; 1635 u32 key; 1636 int ret; 1637 1638 ret = get_user(key, &iocb->aio_key); 1639 if (unlikely(ret)) 1640 return -EFAULT; 1641 1642 ctx = lookup_ioctx(ctx_id); 1643 if (unlikely(!ctx)) 1644 return -EINVAL; 1645 1646 spin_lock_irq(&ctx->ctx_lock); 1647 ret = -EAGAIN; 1648 kiocb = lookup_kiocb(ctx, iocb, key); 1649 if (kiocb && kiocb->ki_cancel) { 1650 cancel = kiocb->ki_cancel; 1651 kiocb->ki_users ++; 1652 kiocbSetCancelled(kiocb); 1653 } else 1654 cancel = NULL; 1655 spin_unlock_irq(&ctx->ctx_lock); 1656 1657 if (NULL != cancel) { 1658 struct io_event tmp; 1659 pr_debug("calling cancel\n"); 1660 memset(&tmp, 0, sizeof(tmp)); 1661 tmp.obj = (u64)(unsigned long)kiocb->ki_obj.user; 1662 tmp.data = kiocb->ki_user_data; 1663 ret = cancel(kiocb, &tmp); 1664 if (!ret) { 1665 /* Cancellation succeeded -- copy the result 1666 * into the user's buffer. 1667 */ 1668 if (copy_to_user(result, &tmp, sizeof(tmp))) 1669 ret = -EFAULT; 1670 } 1671 } else 1672 printk(KERN_DEBUG "iocb has no cancel operation\n"); 1673 1674 put_ioctx(ctx); 1675 1676 return ret; 1677 } 1678 1679 /* io_getevents: 1680 * Attempts to read at least min_nr events and up to nr events from 1681 * the completion queue for the aio_context specified by ctx_id. May 1682 * fail with -EINVAL if ctx_id is invalid, if min_nr is out of range, 1683 * if nr is out of range, if when is out of range. May fail with 1684 * -EFAULT if any of the memory specified to is invalid. May return 1685 * 0 or < min_nr if no events are available and the timeout specified 1686 * by when has elapsed, where when == NULL specifies an infinite 1687 * timeout. Note that the timeout pointed to by when is relative and 1688 * will be updated if not NULL and the operation blocks. Will fail 1689 * with -ENOSYS if not implemented. 1690 */ 1691 asmlinkage long sys_io_getevents(aio_context_t ctx_id, 1692 long min_nr, 1693 long nr, 1694 struct io_event __user *events, 1695 struct timespec __user *timeout) 1696 { 1697 struct kioctx *ioctx = lookup_ioctx(ctx_id); 1698 long ret = -EINVAL; 1699 1700 if (likely(ioctx)) { 1701 if (likely(min_nr <= nr && min_nr >= 0 && nr >= 0)) 1702 ret = read_events(ioctx, min_nr, nr, events, timeout); 1703 put_ioctx(ioctx); 1704 } 1705 1706 return ret; 1707 } 1708 1709 __initcall(aio_setup); 1710 1711 EXPORT_SYMBOL(aio_complete); 1712 EXPORT_SYMBOL(aio_put_req); 1713 EXPORT_SYMBOL(wait_on_sync_kiocb); 1714