| 1 | /* |
| 2 | * An async IO implementation for Linux |
| 3 | * Written by Benjamin LaHaise <bcrl@kvack.org> |
| 4 | * |
| 5 | * Implements an efficient asynchronous io interface. |
| 6 | * |
| 7 | * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved. |
| 8 | * |
| 9 | * See ../COPYING for licensing terms. |
| 10 | */ |
| 11 | #define pr_fmt(fmt) "%s: " fmt, __func__ |
| 12 | |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/init.h> |
| 15 | #include <linux/errno.h> |
| 16 | #include <linux/time.h> |
| 17 | #include <linux/aio_abi.h> |
| 18 | #include <linux/export.h> |
| 19 | #include <linux/syscalls.h> |
| 20 | #include <linux/backing-dev.h> |
| 21 | #include <linux/uio.h> |
| 22 | |
| 23 | #include <linux/sched.h> |
| 24 | #include <linux/fs.h> |
| 25 | #include <linux/file.h> |
| 26 | #include <linux/mm.h> |
| 27 | #include <linux/mman.h> |
| 28 | #include <linux/mmu_context.h> |
| 29 | #include <linux/slab.h> |
| 30 | #include <linux/timer.h> |
| 31 | #include <linux/aio.h> |
| 32 | #include <linux/highmem.h> |
| 33 | #include <linux/workqueue.h> |
| 34 | #include <linux/security.h> |
| 35 | #include <linux/eventfd.h> |
| 36 | #include <linux/blkdev.h> |
| 37 | #include <linux/compat.h> |
| 38 | |
| 39 | #include <asm/kmap_types.h> |
| 40 | #include <asm/uaccess.h> |
| 41 | |
| 42 | #define AIO_RING_MAGIC 0xa10a10a1 |
| 43 | #define AIO_RING_COMPAT_FEATURES 1 |
| 44 | #define AIO_RING_INCOMPAT_FEATURES 0 |
| 45 | struct aio_ring { |
| 46 | unsigned id; /* kernel internal index number */ |
| 47 | unsigned nr; /* number of io_events */ |
| 48 | unsigned head; |
| 49 | unsigned tail; |
| 50 | |
| 51 | unsigned magic; |
| 52 | unsigned compat_features; |
| 53 | unsigned incompat_features; |
| 54 | unsigned header_length; /* size of aio_ring */ |
| 55 | |
| 56 | |
| 57 | struct io_event io_events[0]; |
| 58 | }; /* 128 bytes + ring size */ |
| 59 | |
| 60 | #define AIO_RING_PAGES 8 |
| 61 | struct aio_ring_info { |
| 62 | unsigned long mmap_base; |
| 63 | unsigned long mmap_size; |
| 64 | |
| 65 | struct page **ring_pages; |
| 66 | struct mutex ring_lock; |
| 67 | long nr_pages; |
| 68 | |
| 69 | unsigned nr, tail; |
| 70 | |
| 71 | struct page *internal_pages[AIO_RING_PAGES]; |
| 72 | }; |
| 73 | |
| 74 | static inline unsigned aio_ring_avail(struct aio_ring_info *info, |
| 75 | struct aio_ring *ring) |
| 76 | { |
| 77 | return (ring->head + info->nr - 1 - ring->tail) % info->nr; |
| 78 | } |
| 79 | |
| 80 | struct kioctx { |
| 81 | atomic_t users; |
| 82 | atomic_t dead; |
| 83 | |
| 84 | /* This needs improving */ |
| 85 | unsigned long user_id; |
| 86 | struct hlist_node list; |
| 87 | |
| 88 | wait_queue_head_t wait; |
| 89 | |
| 90 | spinlock_t ctx_lock; |
| 91 | |
| 92 | atomic_t reqs_active; |
| 93 | struct list_head active_reqs; /* used for cancellation */ |
| 94 | |
| 95 | /* sys_io_setup currently limits this to an unsigned int */ |
| 96 | unsigned max_reqs; |
| 97 | |
| 98 | struct aio_ring_info ring_info; |
| 99 | |
| 100 | spinlock_t completion_lock; |
| 101 | |
| 102 | struct rcu_head rcu_head; |
| 103 | struct work_struct rcu_work; |
| 104 | }; |
| 105 | |
| 106 | /*------ sysctl variables----*/ |
| 107 | static DEFINE_SPINLOCK(aio_nr_lock); |
| 108 | unsigned long aio_nr; /* current system wide number of aio requests */ |
| 109 | unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */ |
| 110 | /*----end sysctl variables---*/ |
| 111 | |
| 112 | static struct kmem_cache *kiocb_cachep; |
| 113 | static struct kmem_cache *kioctx_cachep; |
| 114 | |
| 115 | /* aio_setup |
| 116 | * Creates the slab caches used by the aio routines, panic on |
| 117 | * failure as this is done early during the boot sequence. |
| 118 | */ |
| 119 | static int __init aio_setup(void) |
| 120 | { |
| 121 | kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); |
| 122 | kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); |
| 123 | |
| 124 | pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page)); |
| 125 | |
| 126 | return 0; |
| 127 | } |
| 128 | __initcall(aio_setup); |
| 129 | |
| 130 | static void aio_free_ring(struct kioctx *ctx) |
| 131 | { |
| 132 | struct aio_ring_info *info = &ctx->ring_info; |
| 133 | long i; |
| 134 | |
| 135 | for (i=0; i<info->nr_pages; i++) |
| 136 | put_page(info->ring_pages[i]); |
| 137 | |
| 138 | if (info->mmap_size) { |
| 139 | vm_munmap(info->mmap_base, info->mmap_size); |
| 140 | } |
| 141 | |
| 142 | if (info->ring_pages && info->ring_pages != info->internal_pages) |
| 143 | kfree(info->ring_pages); |
| 144 | info->ring_pages = NULL; |
| 145 | info->nr = 0; |
| 146 | } |
| 147 | |
| 148 | static int aio_setup_ring(struct kioctx *ctx) |
| 149 | { |
| 150 | struct aio_ring *ring; |
| 151 | struct aio_ring_info *info = &ctx->ring_info; |
| 152 | unsigned nr_events = ctx->max_reqs; |
| 153 | struct mm_struct *mm = current->mm; |
| 154 | unsigned long size, populate; |
| 155 | int nr_pages; |
| 156 | |
| 157 | /* Compensate for the ring buffer's head/tail overlap entry */ |
| 158 | nr_events += 2; /* 1 is required, 2 for good luck */ |
| 159 | |
| 160 | size = sizeof(struct aio_ring); |
| 161 | size += sizeof(struct io_event) * nr_events; |
| 162 | nr_pages = (size + PAGE_SIZE-1) >> PAGE_SHIFT; |
| 163 | |
| 164 | if (nr_pages < 0) |
| 165 | return -EINVAL; |
| 166 | |
| 167 | nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring)) / sizeof(struct io_event); |
| 168 | |
| 169 | info->nr = 0; |
| 170 | info->ring_pages = info->internal_pages; |
| 171 | if (nr_pages > AIO_RING_PAGES) { |
| 172 | info->ring_pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL); |
| 173 | if (!info->ring_pages) |
| 174 | return -ENOMEM; |
| 175 | } |
| 176 | |
| 177 | info->mmap_size = nr_pages * PAGE_SIZE; |
| 178 | pr_debug("attempting mmap of %lu bytes\n", info->mmap_size); |
| 179 | down_write(&mm->mmap_sem); |
| 180 | info->mmap_base = do_mmap_pgoff(NULL, 0, info->mmap_size, |
| 181 | PROT_READ|PROT_WRITE, |
| 182 | MAP_ANONYMOUS|MAP_PRIVATE, 0, |
| 183 | &populate); |
| 184 | if (IS_ERR((void *)info->mmap_base)) { |
| 185 | up_write(&mm->mmap_sem); |
| 186 | info->mmap_size = 0; |
| 187 | aio_free_ring(ctx); |
| 188 | return -EAGAIN; |
| 189 | } |
| 190 | |
| 191 | pr_debug("mmap address: 0x%08lx\n", info->mmap_base); |
| 192 | info->nr_pages = get_user_pages(current, mm, info->mmap_base, nr_pages, |
| 193 | 1, 0, info->ring_pages, NULL); |
| 194 | up_write(&mm->mmap_sem); |
| 195 | |
| 196 | if (unlikely(info->nr_pages != nr_pages)) { |
| 197 | aio_free_ring(ctx); |
| 198 | return -EAGAIN; |
| 199 | } |
| 200 | if (populate) |
| 201 | mm_populate(info->mmap_base, populate); |
| 202 | |
| 203 | ctx->user_id = info->mmap_base; |
| 204 | |
| 205 | info->nr = nr_events; /* trusted copy */ |
| 206 | |
| 207 | ring = kmap_atomic(info->ring_pages[0]); |
| 208 | ring->nr = nr_events; /* user copy */ |
| 209 | ring->id = ctx->user_id; |
| 210 | ring->head = ring->tail = 0; |
| 211 | ring->magic = AIO_RING_MAGIC; |
| 212 | ring->compat_features = AIO_RING_COMPAT_FEATURES; |
| 213 | ring->incompat_features = AIO_RING_INCOMPAT_FEATURES; |
| 214 | ring->header_length = sizeof(struct aio_ring); |
| 215 | kunmap_atomic(ring); |
| 216 | flush_dcache_page(info->ring_pages[0]); |
| 217 | |
| 218 | return 0; |
| 219 | } |
| 220 | |
| 221 | #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event)) |
| 222 | #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) |
| 223 | #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) |
| 224 | |
| 225 | void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) |
| 226 | { |
| 227 | struct kioctx *ctx = req->ki_ctx; |
| 228 | unsigned long flags; |
| 229 | |
| 230 | spin_lock_irqsave(&ctx->ctx_lock, flags); |
| 231 | |
| 232 | if (!req->ki_list.next) |
| 233 | list_add(&req->ki_list, &ctx->active_reqs); |
| 234 | |
| 235 | req->ki_cancel = cancel; |
| 236 | |
| 237 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); |
| 238 | } |
| 239 | EXPORT_SYMBOL(kiocb_set_cancel_fn); |
| 240 | |
| 241 | static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb, |
| 242 | struct io_event *res) |
| 243 | { |
| 244 | kiocb_cancel_fn *old, *cancel; |
| 245 | int ret = -EINVAL; |
| 246 | |
| 247 | /* |
| 248 | * Don't want to set kiocb->ki_cancel = KIOCB_CANCELLED unless it |
| 249 | * actually has a cancel function, hence the cmpxchg() |
| 250 | */ |
| 251 | |
| 252 | cancel = ACCESS_ONCE(kiocb->ki_cancel); |
| 253 | do { |
| 254 | if (!cancel || cancel == KIOCB_CANCELLED) |
| 255 | return ret; |
| 256 | |
| 257 | old = cancel; |
| 258 | cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED); |
| 259 | } while (cancel != old); |
| 260 | |
| 261 | atomic_inc(&kiocb->ki_users); |
| 262 | spin_unlock_irq(&ctx->ctx_lock); |
| 263 | |
| 264 | memset(res, 0, sizeof(*res)); |
| 265 | res->obj = (u64)(unsigned long)kiocb->ki_obj.user; |
| 266 | res->data = kiocb->ki_user_data; |
| 267 | ret = cancel(kiocb, res); |
| 268 | |
| 269 | spin_lock_irq(&ctx->ctx_lock); |
| 270 | |
| 271 | return ret; |
| 272 | } |
| 273 | |
| 274 | static void free_ioctx_rcu(struct rcu_head *head) |
| 275 | { |
| 276 | struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); |
| 277 | kmem_cache_free(kioctx_cachep, ctx); |
| 278 | } |
| 279 | |
| 280 | /* |
| 281 | * When this function runs, the kioctx has been removed from the "hash table" |
| 282 | * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted - |
| 283 | * now it's safe to cancel any that need to be. |
| 284 | */ |
| 285 | static void free_ioctx(struct kioctx *ctx) |
| 286 | { |
| 287 | struct io_event res; |
| 288 | struct kiocb *req; |
| 289 | |
| 290 | spin_lock_irq(&ctx->ctx_lock); |
| 291 | |
| 292 | while (!list_empty(&ctx->active_reqs)) { |
| 293 | req = list_first_entry(&ctx->active_reqs, |
| 294 | struct kiocb, ki_list); |
| 295 | |
| 296 | list_del_init(&req->ki_list); |
| 297 | kiocb_cancel(ctx, req, &res); |
| 298 | } |
| 299 | |
| 300 | spin_unlock_irq(&ctx->ctx_lock); |
| 301 | |
| 302 | wait_event(ctx->wait, !atomic_read(&ctx->reqs_active)); |
| 303 | |
| 304 | aio_free_ring(ctx); |
| 305 | |
| 306 | spin_lock(&aio_nr_lock); |
| 307 | BUG_ON(aio_nr - ctx->max_reqs > aio_nr); |
| 308 | aio_nr -= ctx->max_reqs; |
| 309 | spin_unlock(&aio_nr_lock); |
| 310 | |
| 311 | pr_debug("freeing %p\n", ctx); |
| 312 | |
| 313 | /* |
| 314 | * Here the call_rcu() is between the wait_event() for reqs_active to |
| 315 | * hit 0, and freeing the ioctx. |
| 316 | * |
| 317 | * aio_complete() decrements reqs_active, but it has to touch the ioctx |
| 318 | * after to issue a wakeup so we use rcu. |
| 319 | */ |
| 320 | call_rcu(&ctx->rcu_head, free_ioctx_rcu); |
| 321 | } |
| 322 | |
| 323 | static void put_ioctx(struct kioctx *ctx) |
| 324 | { |
| 325 | if (unlikely(atomic_dec_and_test(&ctx->users))) |
| 326 | free_ioctx(ctx); |
| 327 | } |
| 328 | |
| 329 | /* ioctx_alloc |
| 330 | * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed. |
| 331 | */ |
| 332 | static struct kioctx *ioctx_alloc(unsigned nr_events) |
| 333 | { |
| 334 | struct mm_struct *mm = current->mm; |
| 335 | struct kioctx *ctx; |
| 336 | int err = -ENOMEM; |
| 337 | |
| 338 | /* Prevent overflows */ |
| 339 | if ((nr_events > (0x10000000U / sizeof(struct io_event))) || |
| 340 | (nr_events > (0x10000000U / sizeof(struct kiocb)))) { |
| 341 | pr_debug("ENOMEM: nr_events too high\n"); |
| 342 | return ERR_PTR(-EINVAL); |
| 343 | } |
| 344 | |
| 345 | if (!nr_events || (unsigned long)nr_events > aio_max_nr) |
| 346 | return ERR_PTR(-EAGAIN); |
| 347 | |
| 348 | ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL); |
| 349 | if (!ctx) |
| 350 | return ERR_PTR(-ENOMEM); |
| 351 | |
| 352 | ctx->max_reqs = nr_events; |
| 353 | |
| 354 | atomic_set(&ctx->users, 2); |
| 355 | atomic_set(&ctx->dead, 0); |
| 356 | spin_lock_init(&ctx->ctx_lock); |
| 357 | spin_lock_init(&ctx->completion_lock); |
| 358 | mutex_init(&ctx->ring_info.ring_lock); |
| 359 | init_waitqueue_head(&ctx->wait); |
| 360 | |
| 361 | INIT_LIST_HEAD(&ctx->active_reqs); |
| 362 | |
| 363 | if (aio_setup_ring(ctx) < 0) |
| 364 | goto out_freectx; |
| 365 | |
| 366 | /* limit the number of system wide aios */ |
| 367 | spin_lock(&aio_nr_lock); |
| 368 | if (aio_nr + nr_events > aio_max_nr || |
| 369 | aio_nr + nr_events < aio_nr) { |
| 370 | spin_unlock(&aio_nr_lock); |
| 371 | goto out_cleanup; |
| 372 | } |
| 373 | aio_nr += ctx->max_reqs; |
| 374 | spin_unlock(&aio_nr_lock); |
| 375 | |
| 376 | /* now link into global list. */ |
| 377 | spin_lock(&mm->ioctx_lock); |
| 378 | hlist_add_head_rcu(&ctx->list, &mm->ioctx_list); |
| 379 | spin_unlock(&mm->ioctx_lock); |
| 380 | |
| 381 | pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n", |
| 382 | ctx, ctx->user_id, mm, ctx->ring_info.nr); |
| 383 | return ctx; |
| 384 | |
| 385 | out_cleanup: |
| 386 | err = -EAGAIN; |
| 387 | aio_free_ring(ctx); |
| 388 | out_freectx: |
| 389 | kmem_cache_free(kioctx_cachep, ctx); |
| 390 | pr_debug("error allocating ioctx %d\n", err); |
| 391 | return ERR_PTR(err); |
| 392 | } |
| 393 | |
| 394 | static void kill_ioctx_work(struct work_struct *work) |
| 395 | { |
| 396 | struct kioctx *ctx = container_of(work, struct kioctx, rcu_work); |
| 397 | |
| 398 | wake_up_all(&ctx->wait); |
| 399 | put_ioctx(ctx); |
| 400 | } |
| 401 | |
| 402 | static void kill_ioctx_rcu(struct rcu_head *head) |
| 403 | { |
| 404 | struct kioctx *ctx = container_of(head, struct kioctx, rcu_head); |
| 405 | |
| 406 | INIT_WORK(&ctx->rcu_work, kill_ioctx_work); |
| 407 | schedule_work(&ctx->rcu_work); |
| 408 | } |
| 409 | |
| 410 | /* kill_ioctx |
| 411 | * Cancels all outstanding aio requests on an aio context. Used |
| 412 | * when the processes owning a context have all exited to encourage |
| 413 | * the rapid destruction of the kioctx. |
| 414 | */ |
| 415 | static void kill_ioctx(struct kioctx *ctx) |
| 416 | { |
| 417 | if (!atomic_xchg(&ctx->dead, 1)) { |
| 418 | hlist_del_rcu(&ctx->list); |
| 419 | /* Between hlist_del_rcu() and dropping the initial ref */ |
| 420 | synchronize_rcu(); |
| 421 | |
| 422 | /* |
| 423 | * We can't punt to workqueue here because put_ioctx() -> |
| 424 | * free_ioctx() will unmap the ringbuffer, and that has to be |
| 425 | * done in the original process's context. kill_ioctx_rcu/work() |
| 426 | * exist for exit_aio(), as in that path free_ioctx() won't do |
| 427 | * the unmap. |
| 428 | */ |
| 429 | kill_ioctx_work(&ctx->rcu_work); |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | /* wait_on_sync_kiocb: |
| 434 | * Waits on the given sync kiocb to complete. |
| 435 | */ |
| 436 | ssize_t wait_on_sync_kiocb(struct kiocb *iocb) |
| 437 | { |
| 438 | while (atomic_read(&iocb->ki_users)) { |
| 439 | set_current_state(TASK_UNINTERRUPTIBLE); |
| 440 | if (!atomic_read(&iocb->ki_users)) |
| 441 | break; |
| 442 | io_schedule(); |
| 443 | } |
| 444 | __set_current_state(TASK_RUNNING); |
| 445 | return iocb->ki_user_data; |
| 446 | } |
| 447 | EXPORT_SYMBOL(wait_on_sync_kiocb); |
| 448 | |
| 449 | /* |
| 450 | * exit_aio: called when the last user of mm goes away. At this point, there is |
| 451 | * no way for any new requests to be submited or any of the io_* syscalls to be |
| 452 | * called on the context. |
| 453 | * |
| 454 | * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on |
| 455 | * them. |
| 456 | */ |
| 457 | void exit_aio(struct mm_struct *mm) |
| 458 | { |
| 459 | struct kioctx *ctx; |
| 460 | struct hlist_node *n; |
| 461 | |
| 462 | hlist_for_each_entry_safe(ctx, n, &mm->ioctx_list, list) { |
| 463 | if (1 != atomic_read(&ctx->users)) |
| 464 | printk(KERN_DEBUG |
| 465 | "exit_aio:ioctx still alive: %d %d %d\n", |
| 466 | atomic_read(&ctx->users), |
| 467 | atomic_read(&ctx->dead), |
| 468 | atomic_read(&ctx->reqs_active)); |
| 469 | /* |
| 470 | * We don't need to bother with munmap() here - |
| 471 | * exit_mmap(mm) is coming and it'll unmap everything. |
| 472 | * Since aio_free_ring() uses non-zero ->mmap_size |
| 473 | * as indicator that it needs to unmap the area, |
| 474 | * just set it to 0; aio_free_ring() is the only |
| 475 | * place that uses ->mmap_size, so it's safe. |
| 476 | */ |
| 477 | ctx->ring_info.mmap_size = 0; |
| 478 | |
| 479 | if (!atomic_xchg(&ctx->dead, 1)) { |
| 480 | hlist_del_rcu(&ctx->list); |
| 481 | call_rcu(&ctx->rcu_head, kill_ioctx_rcu); |
| 482 | } |
| 483 | } |
| 484 | } |
| 485 | |
| 486 | /* aio_get_req |
| 487 | * Allocate a slot for an aio request. Increments the ki_users count |
| 488 | * of the kioctx so that the kioctx stays around until all requests are |
| 489 | * complete. Returns NULL if no requests are free. |
| 490 | * |
| 491 | * Returns with kiocb->ki_users set to 2. The io submit code path holds |
| 492 | * an extra reference while submitting the i/o. |
| 493 | * This prevents races between the aio code path referencing the |
| 494 | * req (after submitting it) and aio_complete() freeing the req. |
| 495 | */ |
| 496 | static struct kiocb *__aio_get_req(struct kioctx *ctx) |
| 497 | { |
| 498 | struct kiocb *req = NULL; |
| 499 | |
| 500 | req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO); |
| 501 | if (unlikely(!req)) |
| 502 | return NULL; |
| 503 | |
| 504 | atomic_set(&req->ki_users, 2); |
| 505 | req->ki_ctx = ctx; |
| 506 | |
| 507 | return req; |
| 508 | } |
| 509 | |
| 510 | /* |
| 511 | * struct kiocb's are allocated in batches to reduce the number of |
| 512 | * times the ctx lock is acquired and released. |
| 513 | */ |
| 514 | #define KIOCB_BATCH_SIZE 32L |
| 515 | struct kiocb_batch { |
| 516 | struct list_head head; |
| 517 | long count; /* number of requests left to allocate */ |
| 518 | }; |
| 519 | |
| 520 | static void kiocb_batch_init(struct kiocb_batch *batch, long total) |
| 521 | { |
| 522 | INIT_LIST_HEAD(&batch->head); |
| 523 | batch->count = total; |
| 524 | } |
| 525 | |
| 526 | static void kiocb_batch_free(struct kioctx *ctx, struct kiocb_batch *batch) |
| 527 | { |
| 528 | struct kiocb *req, *n; |
| 529 | |
| 530 | if (list_empty(&batch->head)) |
| 531 | return; |
| 532 | |
| 533 | spin_lock_irq(&ctx->ctx_lock); |
| 534 | list_for_each_entry_safe(req, n, &batch->head, ki_batch) { |
| 535 | list_del(&req->ki_batch); |
| 536 | kmem_cache_free(kiocb_cachep, req); |
| 537 | atomic_dec(&ctx->reqs_active); |
| 538 | } |
| 539 | spin_unlock_irq(&ctx->ctx_lock); |
| 540 | } |
| 541 | |
| 542 | /* |
| 543 | * Allocate a batch of kiocbs. This avoids taking and dropping the |
| 544 | * context lock a lot during setup. |
| 545 | */ |
| 546 | static int kiocb_batch_refill(struct kioctx *ctx, struct kiocb_batch *batch) |
| 547 | { |
| 548 | unsigned short allocated, to_alloc; |
| 549 | long avail; |
| 550 | struct kiocb *req, *n; |
| 551 | struct aio_ring *ring; |
| 552 | |
| 553 | to_alloc = min(batch->count, KIOCB_BATCH_SIZE); |
| 554 | for (allocated = 0; allocated < to_alloc; allocated++) { |
| 555 | req = __aio_get_req(ctx); |
| 556 | if (!req) |
| 557 | /* allocation failed, go with what we've got */ |
| 558 | break; |
| 559 | list_add(&req->ki_batch, &batch->head); |
| 560 | } |
| 561 | |
| 562 | if (allocated == 0) |
| 563 | goto out; |
| 564 | |
| 565 | spin_lock_irq(&ctx->ctx_lock); |
| 566 | ring = kmap_atomic(ctx->ring_info.ring_pages[0]); |
| 567 | |
| 568 | avail = aio_ring_avail(&ctx->ring_info, ring) - |
| 569 | atomic_read(&ctx->reqs_active); |
| 570 | BUG_ON(avail < 0); |
| 571 | if (avail < allocated) { |
| 572 | /* Trim back the number of requests. */ |
| 573 | list_for_each_entry_safe(req, n, &batch->head, ki_batch) { |
| 574 | list_del(&req->ki_batch); |
| 575 | kmem_cache_free(kiocb_cachep, req); |
| 576 | if (--allocated <= avail) |
| 577 | break; |
| 578 | } |
| 579 | } |
| 580 | |
| 581 | batch->count -= allocated; |
| 582 | atomic_add(allocated, &ctx->reqs_active); |
| 583 | |
| 584 | kunmap_atomic(ring); |
| 585 | spin_unlock_irq(&ctx->ctx_lock); |
| 586 | |
| 587 | out: |
| 588 | return allocated; |
| 589 | } |
| 590 | |
| 591 | static inline struct kiocb *aio_get_req(struct kioctx *ctx, |
| 592 | struct kiocb_batch *batch) |
| 593 | { |
| 594 | struct kiocb *req; |
| 595 | |
| 596 | if (list_empty(&batch->head)) |
| 597 | if (kiocb_batch_refill(ctx, batch) == 0) |
| 598 | return NULL; |
| 599 | req = list_first_entry(&batch->head, struct kiocb, ki_batch); |
| 600 | list_del(&req->ki_batch); |
| 601 | return req; |
| 602 | } |
| 603 | |
| 604 | static void kiocb_free(struct kiocb *req) |
| 605 | { |
| 606 | if (req->ki_filp) |
| 607 | fput(req->ki_filp); |
| 608 | if (req->ki_eventfd != NULL) |
| 609 | eventfd_ctx_put(req->ki_eventfd); |
| 610 | if (req->ki_dtor) |
| 611 | req->ki_dtor(req); |
| 612 | if (req->ki_iovec != &req->ki_inline_vec) |
| 613 | kfree(req->ki_iovec); |
| 614 | kmem_cache_free(kiocb_cachep, req); |
| 615 | } |
| 616 | |
| 617 | void aio_put_req(struct kiocb *req) |
| 618 | { |
| 619 | if (atomic_dec_and_test(&req->ki_users)) |
| 620 | kiocb_free(req); |
| 621 | } |
| 622 | EXPORT_SYMBOL(aio_put_req); |
| 623 | |
| 624 | static struct kioctx *lookup_ioctx(unsigned long ctx_id) |
| 625 | { |
| 626 | struct mm_struct *mm = current->mm; |
| 627 | struct kioctx *ctx, *ret = NULL; |
| 628 | |
| 629 | rcu_read_lock(); |
| 630 | |
| 631 | hlist_for_each_entry_rcu(ctx, &mm->ioctx_list, list) { |
| 632 | if (ctx->user_id == ctx_id) { |
| 633 | atomic_inc(&ctx->users); |
| 634 | ret = ctx; |
| 635 | break; |
| 636 | } |
| 637 | } |
| 638 | |
| 639 | rcu_read_unlock(); |
| 640 | return ret; |
| 641 | } |
| 642 | |
| 643 | /* aio_complete |
| 644 | * Called when the io request on the given iocb is complete. |
| 645 | */ |
| 646 | void aio_complete(struct kiocb *iocb, long res, long res2) |
| 647 | { |
| 648 | struct kioctx *ctx = iocb->ki_ctx; |
| 649 | struct aio_ring_info *info; |
| 650 | struct aio_ring *ring; |
| 651 | struct io_event *ev_page, *event; |
| 652 | unsigned long flags; |
| 653 | unsigned tail, pos; |
| 654 | |
| 655 | /* |
| 656 | * Special case handling for sync iocbs: |
| 657 | * - events go directly into the iocb for fast handling |
| 658 | * - the sync task with the iocb in its stack holds the single iocb |
| 659 | * ref, no other paths have a way to get another ref |
| 660 | * - the sync task helpfully left a reference to itself in the iocb |
| 661 | */ |
| 662 | if (is_sync_kiocb(iocb)) { |
| 663 | BUG_ON(atomic_read(&iocb->ki_users) != 1); |
| 664 | iocb->ki_user_data = res; |
| 665 | atomic_set(&iocb->ki_users, 0); |
| 666 | wake_up_process(iocb->ki_obj.tsk); |
| 667 | return; |
| 668 | } |
| 669 | |
| 670 | info = &ctx->ring_info; |
| 671 | |
| 672 | /* |
| 673 | * Take rcu_read_lock() in case the kioctx is being destroyed, as we |
| 674 | * need to issue a wakeup after decrementing reqs_active. |
| 675 | */ |
| 676 | rcu_read_lock(); |
| 677 | |
| 678 | if (iocb->ki_list.next) { |
| 679 | unsigned long flags; |
| 680 | |
| 681 | spin_lock_irqsave(&ctx->ctx_lock, flags); |
| 682 | list_del(&iocb->ki_list); |
| 683 | spin_unlock_irqrestore(&ctx->ctx_lock, flags); |
| 684 | } |
| 685 | |
| 686 | /* |
| 687 | * cancelled requests don't get events, userland was given one |
| 688 | * when the event got cancelled. |
| 689 | */ |
| 690 | if (unlikely(xchg(&iocb->ki_cancel, |
| 691 | KIOCB_CANCELLED) == KIOCB_CANCELLED)) |
| 692 | goto put_rq; |
| 693 | |
| 694 | /* |
| 695 | * Add a completion event to the ring buffer. Must be done holding |
| 696 | * ctx->ctx_lock to prevent other code from messing with the tail |
| 697 | * pointer since we might be called from irq context. |
| 698 | */ |
| 699 | spin_lock_irqsave(&ctx->completion_lock, flags); |
| 700 | |
| 701 | tail = info->tail; |
| 702 | pos = tail + AIO_EVENTS_OFFSET; |
| 703 | |
| 704 | if (++tail >= info->nr) |
| 705 | tail = 0; |
| 706 | |
| 707 | ev_page = kmap_atomic(info->ring_pages[pos / AIO_EVENTS_PER_PAGE]); |
| 708 | event = ev_page + pos % AIO_EVENTS_PER_PAGE; |
| 709 | |
| 710 | event->obj = (u64)(unsigned long)iocb->ki_obj.user; |
| 711 | event->data = iocb->ki_user_data; |
| 712 | event->res = res; |
| 713 | event->res2 = res2; |
| 714 | |
| 715 | kunmap_atomic(ev_page); |
| 716 | flush_dcache_page(info->ring_pages[pos / AIO_EVENTS_PER_PAGE]); |
| 717 | |
| 718 | pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n", |
| 719 | ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, |
| 720 | res, res2); |
| 721 | |
| 722 | /* after flagging the request as done, we |
| 723 | * must never even look at it again |
| 724 | */ |
| 725 | smp_wmb(); /* make event visible before updating tail */ |
| 726 | |
| 727 | info->tail = tail; |
| 728 | |
| 729 | ring = kmap_atomic(info->ring_pages[0]); |
| 730 | ring->tail = tail; |
| 731 | kunmap_atomic(ring); |
| 732 | flush_dcache_page(info->ring_pages[0]); |
| 733 | |
| 734 | spin_unlock_irqrestore(&ctx->completion_lock, flags); |
| 735 | |
| 736 | pr_debug("added to ring %p at [%u]\n", iocb, tail); |
| 737 | |
| 738 | /* |
| 739 | * Check if the user asked us to deliver the result through an |
| 740 | * eventfd. The eventfd_signal() function is safe to be called |
| 741 | * from IRQ context. |
| 742 | */ |
| 743 | if (iocb->ki_eventfd != NULL) |
| 744 | eventfd_signal(iocb->ki_eventfd, 1); |
| 745 | |
| 746 | put_rq: |
| 747 | /* everything turned out well, dispose of the aiocb. */ |
| 748 | aio_put_req(iocb); |
| 749 | atomic_dec(&ctx->reqs_active); |
| 750 | |
| 751 | /* |
| 752 | * We have to order our ring_info tail store above and test |
| 753 | * of the wait list below outside the wait lock. This is |
| 754 | * like in wake_up_bit() where clearing a bit has to be |
| 755 | * ordered with the unlocked test. |
| 756 | */ |
| 757 | smp_mb(); |
| 758 | |
| 759 | if (waitqueue_active(&ctx->wait)) |
| 760 | wake_up(&ctx->wait); |
| 761 | |
| 762 | rcu_read_unlock(); |
| 763 | } |
| 764 | EXPORT_SYMBOL(aio_complete); |
| 765 | |
| 766 | /* aio_read_events |
| 767 | * Pull an event off of the ioctx's event ring. Returns the number of |
| 768 | * events fetched |
| 769 | */ |
| 770 | static long aio_read_events_ring(struct kioctx *ctx, |
| 771 | struct io_event __user *event, long nr) |
| 772 | { |
| 773 | struct aio_ring_info *info = &ctx->ring_info; |
| 774 | struct aio_ring *ring; |
| 775 | unsigned head, pos; |
| 776 | long ret = 0; |
| 777 | int copy_ret; |
| 778 | |
| 779 | mutex_lock(&info->ring_lock); |
| 780 | |
| 781 | ring = kmap_atomic(info->ring_pages[0]); |
| 782 | head = ring->head; |
| 783 | kunmap_atomic(ring); |
| 784 | |
| 785 | pr_debug("h%u t%u m%u\n", head, info->tail, info->nr); |
| 786 | |
| 787 | if (head == info->tail) |
| 788 | goto out; |
| 789 | |
| 790 | while (ret < nr) { |
| 791 | long avail; |
| 792 | struct io_event *ev; |
| 793 | struct page *page; |
| 794 | |
| 795 | avail = (head <= info->tail ? info->tail : info->nr) - head; |
| 796 | if (head == info->tail) |
| 797 | break; |
| 798 | |
| 799 | avail = min(avail, nr - ret); |
| 800 | avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - |
| 801 | ((head + AIO_EVENTS_OFFSET) % AIO_EVENTS_PER_PAGE)); |
| 802 | |
| 803 | pos = head + AIO_EVENTS_OFFSET; |
| 804 | page = info->ring_pages[pos / AIO_EVENTS_PER_PAGE]; |
| 805 | pos %= AIO_EVENTS_PER_PAGE; |
| 806 | |
| 807 | ev = kmap(page); |
| 808 | copy_ret = copy_to_user(event + ret, ev + pos, |
| 809 | sizeof(*ev) * avail); |
| 810 | kunmap(page); |
| 811 | |
| 812 | if (unlikely(copy_ret)) { |
| 813 | ret = -EFAULT; |
| 814 | goto out; |
| 815 | } |
| 816 | |
| 817 | ret += avail; |
| 818 | head += avail; |
| 819 | head %= info->nr; |
| 820 | } |
| 821 | |
| 822 | ring = kmap_atomic(info->ring_pages[0]); |
| 823 | ring->head = head; |
| 824 | kunmap_atomic(ring); |
| 825 | flush_dcache_page(info->ring_pages[0]); |
| 826 | |
| 827 | pr_debug("%li h%u t%u\n", ret, head, info->tail); |
| 828 | out: |
| 829 | mutex_unlock(&info->ring_lock); |
| 830 | |
| 831 | return ret; |
| 832 | } |
| 833 | |
| 834 | static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr, |
| 835 | struct io_event __user *event, long *i) |
| 836 | { |
| 837 | long ret = aio_read_events_ring(ctx, event + *i, nr - *i); |
| 838 | |
| 839 | if (ret > 0) |
| 840 | *i += ret; |
| 841 | |
| 842 | if (unlikely(atomic_read(&ctx->dead))) |
| 843 | ret = -EINVAL; |
| 844 | |
| 845 | if (!*i) |
| 846 | *i = ret; |
| 847 | |
| 848 | return ret < 0 || *i >= min_nr; |
| 849 | } |
| 850 | |
| 851 | static long read_events(struct kioctx *ctx, long min_nr, long nr, |
| 852 | struct io_event __user *event, |
| 853 | struct timespec __user *timeout) |
| 854 | { |
| 855 | ktime_t until = { .tv64 = KTIME_MAX }; |
| 856 | long ret = 0; |
| 857 | |
| 858 | if (timeout) { |
| 859 | struct timespec ts; |
| 860 | |
| 861 | if (unlikely(copy_from_user(&ts, timeout, sizeof(ts)))) |
| 862 | return -EFAULT; |
| 863 | |
| 864 | until = timespec_to_ktime(ts); |
| 865 | } |
| 866 | |
| 867 | /* |
| 868 | * Note that aio_read_events() is being called as the conditional - i.e. |
| 869 | * we're calling it after prepare_to_wait() has set task state to |
| 870 | * TASK_INTERRUPTIBLE. |
| 871 | * |
| 872 | * But aio_read_events() can block, and if it blocks it's going to flip |
| 873 | * the task state back to TASK_RUNNING. |
| 874 | * |
| 875 | * This should be ok, provided it doesn't flip the state back to |
| 876 | * TASK_RUNNING and return 0 too much - that causes us to spin. That |
| 877 | * will only happen if the mutex_lock() call blocks, and we then find |
| 878 | * the ringbuffer empty. So in practice we should be ok, but it's |
| 879 | * something to be aware of when touching this code. |
| 880 | */ |
| 881 | wait_event_interruptible_hrtimeout(ctx->wait, |
| 882 | aio_read_events(ctx, min_nr, nr, event, &ret), until); |
| 883 | |
| 884 | if (!ret && signal_pending(current)) |
| 885 | ret = -EINTR; |
| 886 | |
| 887 | return ret; |
| 888 | } |
| 889 | |
| 890 | /* sys_io_setup: |
| 891 | * Create an aio_context capable of receiving at least nr_events. |
| 892 | * ctxp must not point to an aio_context that already exists, and |
| 893 | * must be initialized to 0 prior to the call. On successful |
| 894 | * creation of the aio_context, *ctxp is filled in with the resulting |
| 895 | * handle. May fail with -EINVAL if *ctxp is not initialized, |
| 896 | * if the specified nr_events exceeds internal limits. May fail |
| 897 | * with -EAGAIN if the specified nr_events exceeds the user's limit |
| 898 | * of available events. May fail with -ENOMEM if insufficient kernel |
| 899 | * resources are available. May fail with -EFAULT if an invalid |
| 900 | * pointer is passed for ctxp. Will fail with -ENOSYS if not |
| 901 | * implemented. |
| 902 | */ |
| 903 | SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp) |
| 904 | { |
| 905 | struct kioctx *ioctx = NULL; |
| 906 | unsigned long ctx; |
| 907 | long ret; |
| 908 | |
| 909 | ret = get_user(ctx, ctxp); |
| 910 | if (unlikely(ret)) |
| 911 | goto out; |
| 912 | |
| 913 | ret = -EINVAL; |
| 914 | if (unlikely(ctx || nr_events == 0)) { |
| 915 | pr_debug("EINVAL: io_setup: ctx %lu nr_events %u\n", |
| 916 | ctx, nr_events); |
| 917 | goto out; |
| 918 | } |
| 919 | |
| 920 | ioctx = ioctx_alloc(nr_events); |
| 921 | ret = PTR_ERR(ioctx); |
| 922 | if (!IS_ERR(ioctx)) { |
| 923 | ret = put_user(ioctx->user_id, ctxp); |
| 924 | if (ret) |
| 925 | kill_ioctx(ioctx); |
| 926 | put_ioctx(ioctx); |
| 927 | } |
| 928 | |
| 929 | out: |
| 930 | return ret; |
| 931 | } |
| 932 | |
| 933 | /* sys_io_destroy: |
| 934 | * Destroy the aio_context specified. May cancel any outstanding |
| 935 | * AIOs and block on completion. Will fail with -ENOSYS if not |
| 936 | * implemented. May fail with -EINVAL if the context pointed to |
| 937 | * is invalid. |
| 938 | */ |
| 939 | SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx) |
| 940 | { |
| 941 | struct kioctx *ioctx = lookup_ioctx(ctx); |
| 942 | if (likely(NULL != ioctx)) { |
| 943 | kill_ioctx(ioctx); |
| 944 | put_ioctx(ioctx); |
| 945 | return 0; |
| 946 | } |
| 947 | pr_debug("EINVAL: io_destroy: invalid context id\n"); |
| 948 | return -EINVAL; |
| 949 | } |
| 950 | |
| 951 | static void aio_advance_iovec(struct kiocb *iocb, ssize_t ret) |
| 952 | { |
| 953 | struct iovec *iov = &iocb->ki_iovec[iocb->ki_cur_seg]; |
| 954 | |
| 955 | BUG_ON(ret <= 0); |
| 956 | |
| 957 | while (iocb->ki_cur_seg < iocb->ki_nr_segs && ret > 0) { |
| 958 | ssize_t this = min((ssize_t)iov->iov_len, ret); |
| 959 | iov->iov_base += this; |
| 960 | iov->iov_len -= this; |
| 961 | iocb->ki_left -= this; |
| 962 | ret -= this; |
| 963 | if (iov->iov_len == 0) { |
| 964 | iocb->ki_cur_seg++; |
| 965 | iov++; |
| 966 | } |
| 967 | } |
| 968 | |
| 969 | /* the caller should not have done more io than what fit in |
| 970 | * the remaining iovecs */ |
| 971 | BUG_ON(ret > 0 && iocb->ki_left == 0); |
| 972 | } |
| 973 | |
| 974 | static ssize_t aio_rw_vect_retry(struct kiocb *iocb) |
| 975 | { |
| 976 | struct file *file = iocb->ki_filp; |
| 977 | struct address_space *mapping = file->f_mapping; |
| 978 | struct inode *inode = mapping->host; |
| 979 | ssize_t (*rw_op)(struct kiocb *, const struct iovec *, |
| 980 | unsigned long, loff_t); |
| 981 | ssize_t ret = 0; |
| 982 | unsigned short opcode; |
| 983 | |
| 984 | if ((iocb->ki_opcode == IOCB_CMD_PREADV) || |
| 985 | (iocb->ki_opcode == IOCB_CMD_PREAD)) { |
| 986 | rw_op = file->f_op->aio_read; |
| 987 | opcode = IOCB_CMD_PREADV; |
| 988 | } else { |
| 989 | rw_op = file->f_op->aio_write; |
| 990 | opcode = IOCB_CMD_PWRITEV; |
| 991 | } |
| 992 | |
| 993 | /* This matches the pread()/pwrite() logic */ |
| 994 | if (iocb->ki_pos < 0) |
| 995 | return -EINVAL; |
| 996 | |
| 997 | if (opcode == IOCB_CMD_PWRITEV) |
| 998 | file_start_write(file); |
| 999 | do { |
| 1000 | ret = rw_op(iocb, &iocb->ki_iovec[iocb->ki_cur_seg], |
| 1001 | iocb->ki_nr_segs - iocb->ki_cur_seg, |
| 1002 | iocb->ki_pos); |
| 1003 | if (ret > 0) |
| 1004 | aio_advance_iovec(iocb, ret); |
| 1005 | |
| 1006 | /* retry all partial writes. retry partial reads as long as its a |
| 1007 | * regular file. */ |
| 1008 | } while (ret > 0 && iocb->ki_left > 0 && |
| 1009 | (opcode == IOCB_CMD_PWRITEV || |
| 1010 | (!S_ISFIFO(inode->i_mode) && !S_ISSOCK(inode->i_mode)))); |
| 1011 | if (opcode == IOCB_CMD_PWRITEV) |
| 1012 | file_end_write(file); |
| 1013 | |
| 1014 | /* This means we must have transferred all that we could */ |
| 1015 | /* No need to retry anymore */ |
| 1016 | if ((ret == 0) || (iocb->ki_left == 0)) |
| 1017 | ret = iocb->ki_nbytes - iocb->ki_left; |
| 1018 | |
| 1019 | /* If we managed to write some out we return that, rather than |
| 1020 | * the eventual error. */ |
| 1021 | if (opcode == IOCB_CMD_PWRITEV |
| 1022 | && ret < 0 && ret != -EIOCBQUEUED |
| 1023 | && iocb->ki_nbytes - iocb->ki_left) |
| 1024 | ret = iocb->ki_nbytes - iocb->ki_left; |
| 1025 | |
| 1026 | return ret; |
| 1027 | } |
| 1028 | |
| 1029 | static ssize_t aio_fdsync(struct kiocb *iocb) |
| 1030 | { |
| 1031 | struct file *file = iocb->ki_filp; |
| 1032 | ssize_t ret = -EINVAL; |
| 1033 | |
| 1034 | if (file->f_op->aio_fsync) |
| 1035 | ret = file->f_op->aio_fsync(iocb, 1); |
| 1036 | return ret; |
| 1037 | } |
| 1038 | |
| 1039 | static ssize_t aio_fsync(struct kiocb *iocb) |
| 1040 | { |
| 1041 | struct file *file = iocb->ki_filp; |
| 1042 | ssize_t ret = -EINVAL; |
| 1043 | |
| 1044 | if (file->f_op->aio_fsync) |
| 1045 | ret = file->f_op->aio_fsync(iocb, 0); |
| 1046 | return ret; |
| 1047 | } |
| 1048 | |
| 1049 | static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat) |
| 1050 | { |
| 1051 | ssize_t ret; |
| 1052 | |
| 1053 | #ifdef CONFIG_COMPAT |
| 1054 | if (compat) |
| 1055 | ret = compat_rw_copy_check_uvector(type, |
| 1056 | (struct compat_iovec __user *)kiocb->ki_buf, |
| 1057 | kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec, |
| 1058 | &kiocb->ki_iovec); |
| 1059 | else |
| 1060 | #endif |
| 1061 | ret = rw_copy_check_uvector(type, |
| 1062 | (struct iovec __user *)kiocb->ki_buf, |
| 1063 | kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec, |
| 1064 | &kiocb->ki_iovec); |
| 1065 | if (ret < 0) |
| 1066 | goto out; |
| 1067 | |
| 1068 | ret = rw_verify_area(type, kiocb->ki_filp, &kiocb->ki_pos, ret); |
| 1069 | if (ret < 0) |
| 1070 | goto out; |
| 1071 | |
| 1072 | kiocb->ki_nr_segs = kiocb->ki_nbytes; |
| 1073 | kiocb->ki_cur_seg = 0; |
| 1074 | /* ki_nbytes/left now reflect bytes instead of segs */ |
| 1075 | kiocb->ki_nbytes = ret; |
| 1076 | kiocb->ki_left = ret; |
| 1077 | |
| 1078 | ret = 0; |
| 1079 | out: |
| 1080 | return ret; |
| 1081 | } |
| 1082 | |
| 1083 | static ssize_t aio_setup_single_vector(int type, struct file * file, struct kiocb *kiocb) |
| 1084 | { |
| 1085 | int bytes; |
| 1086 | |
| 1087 | bytes = rw_verify_area(type, file, &kiocb->ki_pos, kiocb->ki_left); |
| 1088 | if (bytes < 0) |
| 1089 | return bytes; |
| 1090 | |
| 1091 | kiocb->ki_iovec = &kiocb->ki_inline_vec; |
| 1092 | kiocb->ki_iovec->iov_base = kiocb->ki_buf; |
| 1093 | kiocb->ki_iovec->iov_len = bytes; |
| 1094 | kiocb->ki_nr_segs = 1; |
| 1095 | kiocb->ki_cur_seg = 0; |
| 1096 | return 0; |
| 1097 | } |
| 1098 | |
| 1099 | /* |
| 1100 | * aio_setup_iocb: |
| 1101 | * Performs the initial checks and aio retry method |
| 1102 | * setup for the kiocb at the time of io submission. |
| 1103 | */ |
| 1104 | static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat) |
| 1105 | { |
| 1106 | struct file *file = kiocb->ki_filp; |
| 1107 | ssize_t ret = 0; |
| 1108 | |
| 1109 | switch (kiocb->ki_opcode) { |
| 1110 | case IOCB_CMD_PREAD: |
| 1111 | ret = -EBADF; |
| 1112 | if (unlikely(!(file->f_mode & FMODE_READ))) |
| 1113 | break; |
| 1114 | ret = -EFAULT; |
| 1115 | if (unlikely(!access_ok(VERIFY_WRITE, kiocb->ki_buf, |
| 1116 | kiocb->ki_left))) |
| 1117 | break; |
| 1118 | ret = aio_setup_single_vector(READ, file, kiocb); |
| 1119 | if (ret) |
| 1120 | break; |
| 1121 | ret = -EINVAL; |
| 1122 | if (file->f_op->aio_read) |
| 1123 | kiocb->ki_retry = aio_rw_vect_retry; |
| 1124 | break; |
| 1125 | case IOCB_CMD_PWRITE: |
| 1126 | ret = -EBADF; |
| 1127 | if (unlikely(!(file->f_mode & FMODE_WRITE))) |
| 1128 | break; |
| 1129 | ret = -EFAULT; |
| 1130 | if (unlikely(!access_ok(VERIFY_READ, kiocb->ki_buf, |
| 1131 | kiocb->ki_left))) |
| 1132 | break; |
| 1133 | ret = aio_setup_single_vector(WRITE, file, kiocb); |
| 1134 | if (ret) |
| 1135 | break; |
| 1136 | ret = -EINVAL; |
| 1137 | if (file->f_op->aio_write) |
| 1138 | kiocb->ki_retry = aio_rw_vect_retry; |
| 1139 | break; |
| 1140 | case IOCB_CMD_PREADV: |
| 1141 | ret = -EBADF; |
| 1142 | if (unlikely(!(file->f_mode & FMODE_READ))) |
| 1143 | break; |
| 1144 | ret = aio_setup_vectored_rw(READ, kiocb, compat); |
| 1145 | if (ret) |
| 1146 | break; |
| 1147 | ret = -EINVAL; |
| 1148 | if (file->f_op->aio_read) |
| 1149 | kiocb->ki_retry = aio_rw_vect_retry; |
| 1150 | break; |
| 1151 | case IOCB_CMD_PWRITEV: |
| 1152 | ret = -EBADF; |
| 1153 | if (unlikely(!(file->f_mode & FMODE_WRITE))) |
| 1154 | break; |
| 1155 | ret = aio_setup_vectored_rw(WRITE, kiocb, compat); |
| 1156 | if (ret) |
| 1157 | break; |
| 1158 | ret = -EINVAL; |
| 1159 | if (file->f_op->aio_write) |
| 1160 | kiocb->ki_retry = aio_rw_vect_retry; |
| 1161 | break; |
| 1162 | case IOCB_CMD_FDSYNC: |
| 1163 | ret = -EINVAL; |
| 1164 | if (file->f_op->aio_fsync) |
| 1165 | kiocb->ki_retry = aio_fdsync; |
| 1166 | break; |
| 1167 | case IOCB_CMD_FSYNC: |
| 1168 | ret = -EINVAL; |
| 1169 | if (file->f_op->aio_fsync) |
| 1170 | kiocb->ki_retry = aio_fsync; |
| 1171 | break; |
| 1172 | default: |
| 1173 | pr_debug("EINVAL: no operation provided\n"); |
| 1174 | ret = -EINVAL; |
| 1175 | } |
| 1176 | |
| 1177 | if (!kiocb->ki_retry) |
| 1178 | return ret; |
| 1179 | |
| 1180 | return 0; |
| 1181 | } |
| 1182 | |
| 1183 | static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, |
| 1184 | struct iocb *iocb, struct kiocb_batch *batch, |
| 1185 | bool compat) |
| 1186 | { |
| 1187 | struct kiocb *req; |
| 1188 | ssize_t ret; |
| 1189 | |
| 1190 | /* enforce forwards compatibility on users */ |
| 1191 | if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) { |
| 1192 | pr_debug("EINVAL: reserve field set\n"); |
| 1193 | return -EINVAL; |
| 1194 | } |
| 1195 | |
| 1196 | /* prevent overflows */ |
| 1197 | if (unlikely( |
| 1198 | (iocb->aio_buf != (unsigned long)iocb->aio_buf) || |
| 1199 | (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) || |
| 1200 | ((ssize_t)iocb->aio_nbytes < 0) |
| 1201 | )) { |
| 1202 | pr_debug("EINVAL: io_submit: overflow check\n"); |
| 1203 | return -EINVAL; |
| 1204 | } |
| 1205 | |
| 1206 | req = aio_get_req(ctx, batch); /* returns with 2 references to req */ |
| 1207 | if (unlikely(!req)) |
| 1208 | return -EAGAIN; |
| 1209 | |
| 1210 | req->ki_filp = fget(iocb->aio_fildes); |
| 1211 | if (unlikely(!req->ki_filp)) { |
| 1212 | ret = -EBADF; |
| 1213 | goto out_put_req; |
| 1214 | } |
| 1215 | |
| 1216 | if (iocb->aio_flags & IOCB_FLAG_RESFD) { |
| 1217 | /* |
| 1218 | * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an |
| 1219 | * instance of the file* now. The file descriptor must be |
| 1220 | * an eventfd() fd, and will be signaled for each completed |
| 1221 | * event using the eventfd_signal() function. |
| 1222 | */ |
| 1223 | req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd); |
| 1224 | if (IS_ERR(req->ki_eventfd)) { |
| 1225 | ret = PTR_ERR(req->ki_eventfd); |
| 1226 | req->ki_eventfd = NULL; |
| 1227 | goto out_put_req; |
| 1228 | } |
| 1229 | } |
| 1230 | |
| 1231 | ret = put_user(req->ki_key, &user_iocb->aio_key); |
| 1232 | if (unlikely(ret)) { |
| 1233 | pr_debug("EFAULT: aio_key\n"); |
| 1234 | goto out_put_req; |
| 1235 | } |
| 1236 | |
| 1237 | req->ki_obj.user = user_iocb; |
| 1238 | req->ki_user_data = iocb->aio_data; |
| 1239 | req->ki_pos = iocb->aio_offset; |
| 1240 | |
| 1241 | req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf; |
| 1242 | req->ki_left = req->ki_nbytes = iocb->aio_nbytes; |
| 1243 | req->ki_opcode = iocb->aio_lio_opcode; |
| 1244 | |
| 1245 | ret = aio_setup_iocb(req, compat); |
| 1246 | if (ret) |
| 1247 | goto out_put_req; |
| 1248 | |
| 1249 | ret = req->ki_retry(req); |
| 1250 | if (ret != -EIOCBQUEUED) { |
| 1251 | /* |
| 1252 | * There's no easy way to restart the syscall since other AIO's |
| 1253 | * may be already running. Just fail this IO with EINTR. |
| 1254 | */ |
| 1255 | if (unlikely(ret == -ERESTARTSYS || ret == -ERESTARTNOINTR || |
| 1256 | ret == -ERESTARTNOHAND || |
| 1257 | ret == -ERESTART_RESTARTBLOCK)) |
| 1258 | ret = -EINTR; |
| 1259 | aio_complete(req, ret, 0); |
| 1260 | } |
| 1261 | |
| 1262 | aio_put_req(req); /* drop extra ref to req */ |
| 1263 | return 0; |
| 1264 | |
| 1265 | out_put_req: |
| 1266 | atomic_dec(&ctx->reqs_active); |
| 1267 | aio_put_req(req); /* drop extra ref to req */ |
| 1268 | aio_put_req(req); /* drop i/o ref to req */ |
| 1269 | return ret; |
| 1270 | } |
| 1271 | |
| 1272 | long do_io_submit(aio_context_t ctx_id, long nr, |
| 1273 | struct iocb __user *__user *iocbpp, bool compat) |
| 1274 | { |
| 1275 | struct kioctx *ctx; |
| 1276 | long ret = 0; |
| 1277 | int i = 0; |
| 1278 | struct blk_plug plug; |
| 1279 | struct kiocb_batch batch; |
| 1280 | |
| 1281 | if (unlikely(nr < 0)) |
| 1282 | return -EINVAL; |
| 1283 | |
| 1284 | if (unlikely(nr > LONG_MAX/sizeof(*iocbpp))) |
| 1285 | nr = LONG_MAX/sizeof(*iocbpp); |
| 1286 | |
| 1287 | if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) |
| 1288 | return -EFAULT; |
| 1289 | |
| 1290 | ctx = lookup_ioctx(ctx_id); |
| 1291 | if (unlikely(!ctx)) { |
| 1292 | pr_debug("EINVAL: invalid context id\n"); |
| 1293 | return -EINVAL; |
| 1294 | } |
| 1295 | |
| 1296 | kiocb_batch_init(&batch, nr); |
| 1297 | |
| 1298 | blk_start_plug(&plug); |
| 1299 | |
| 1300 | /* |
| 1301 | * AKPM: should this return a partial result if some of the IOs were |
| 1302 | * successfully submitted? |
| 1303 | */ |
| 1304 | for (i=0; i<nr; i++) { |
| 1305 | struct iocb __user *user_iocb; |
| 1306 | struct iocb tmp; |
| 1307 | |
| 1308 | if (unlikely(__get_user(user_iocb, iocbpp + i))) { |
| 1309 | ret = -EFAULT; |
| 1310 | break; |
| 1311 | } |
| 1312 | |
| 1313 | if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) { |
| 1314 | ret = -EFAULT; |
| 1315 | break; |
| 1316 | } |
| 1317 | |
| 1318 | ret = io_submit_one(ctx, user_iocb, &tmp, &batch, compat); |
| 1319 | if (ret) |
| 1320 | break; |
| 1321 | } |
| 1322 | blk_finish_plug(&plug); |
| 1323 | |
| 1324 | kiocb_batch_free(ctx, &batch); |
| 1325 | put_ioctx(ctx); |
| 1326 | return i ? i : ret; |
| 1327 | } |
| 1328 | |
| 1329 | /* sys_io_submit: |
| 1330 | * Queue the nr iocbs pointed to by iocbpp for processing. Returns |
| 1331 | * the number of iocbs queued. May return -EINVAL if the aio_context |
| 1332 | * specified by ctx_id is invalid, if nr is < 0, if the iocb at |
| 1333 | * *iocbpp[0] is not properly initialized, if the operation specified |
| 1334 | * is invalid for the file descriptor in the iocb. May fail with |
| 1335 | * -EFAULT if any of the data structures point to invalid data. May |
| 1336 | * fail with -EBADF if the file descriptor specified in the first |
| 1337 | * iocb is invalid. May fail with -EAGAIN if insufficient resources |
| 1338 | * are available to queue any iocbs. Will return 0 if nr is 0. Will |
| 1339 | * fail with -ENOSYS if not implemented. |
| 1340 | */ |
| 1341 | SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, |
| 1342 | struct iocb __user * __user *, iocbpp) |
| 1343 | { |
| 1344 | return do_io_submit(ctx_id, nr, iocbpp, 0); |
| 1345 | } |
| 1346 | |
| 1347 | /* lookup_kiocb |
| 1348 | * Finds a given iocb for cancellation. |
| 1349 | */ |
| 1350 | static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, |
| 1351 | u32 key) |
| 1352 | { |
| 1353 | struct list_head *pos; |
| 1354 | |
| 1355 | assert_spin_locked(&ctx->ctx_lock); |
| 1356 | |
| 1357 | /* TODO: use a hash or array, this sucks. */ |
| 1358 | list_for_each(pos, &ctx->active_reqs) { |
| 1359 | struct kiocb *kiocb = list_kiocb(pos); |
| 1360 | if (kiocb->ki_obj.user == iocb && kiocb->ki_key == key) |
| 1361 | return kiocb; |
| 1362 | } |
| 1363 | return NULL; |
| 1364 | } |
| 1365 | |
| 1366 | /* sys_io_cancel: |
| 1367 | * Attempts to cancel an iocb previously passed to io_submit. If |
| 1368 | * the operation is successfully cancelled, the resulting event is |
| 1369 | * copied into the memory pointed to by result without being placed |
| 1370 | * into the completion queue and 0 is returned. May fail with |
| 1371 | * -EFAULT if any of the data structures pointed to are invalid. |
| 1372 | * May fail with -EINVAL if aio_context specified by ctx_id is |
| 1373 | * invalid. May fail with -EAGAIN if the iocb specified was not |
| 1374 | * cancelled. Will fail with -ENOSYS if not implemented. |
| 1375 | */ |
| 1376 | SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, |
| 1377 | struct io_event __user *, result) |
| 1378 | { |
| 1379 | struct io_event res; |
| 1380 | struct kioctx *ctx; |
| 1381 | struct kiocb *kiocb; |
| 1382 | u32 key; |
| 1383 | int ret; |
| 1384 | |
| 1385 | ret = get_user(key, &iocb->aio_key); |
| 1386 | if (unlikely(ret)) |
| 1387 | return -EFAULT; |
| 1388 | |
| 1389 | ctx = lookup_ioctx(ctx_id); |
| 1390 | if (unlikely(!ctx)) |
| 1391 | return -EINVAL; |
| 1392 | |
| 1393 | spin_lock_irq(&ctx->ctx_lock); |
| 1394 | |
| 1395 | kiocb = lookup_kiocb(ctx, iocb, key); |
| 1396 | if (kiocb) |
| 1397 | ret = kiocb_cancel(ctx, kiocb, &res); |
| 1398 | else |
| 1399 | ret = -EINVAL; |
| 1400 | |
| 1401 | spin_unlock_irq(&ctx->ctx_lock); |
| 1402 | |
| 1403 | if (!ret) { |
| 1404 | /* Cancellation succeeded -- copy the result |
| 1405 | * into the user's buffer. |
| 1406 | */ |
| 1407 | if (copy_to_user(result, &res, sizeof(res))) |
| 1408 | ret = -EFAULT; |
| 1409 | } |
| 1410 | |
| 1411 | put_ioctx(ctx); |
| 1412 | |
| 1413 | return ret; |
| 1414 | } |
| 1415 | |
| 1416 | /* io_getevents: |
| 1417 | * Attempts to read at least min_nr events and up to nr events from |
| 1418 | * the completion queue for the aio_context specified by ctx_id. If |
| 1419 | * it succeeds, the number of read events is returned. May fail with |
| 1420 | * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is |
| 1421 | * out of range, if timeout is out of range. May fail with -EFAULT |
| 1422 | * if any of the memory specified is invalid. May return 0 or |
| 1423 | * < min_nr if the timeout specified by timeout has elapsed |
| 1424 | * before sufficient events are available, where timeout == NULL |
| 1425 | * specifies an infinite timeout. Note that the timeout pointed to by |
| 1426 | * timeout is relative and will be updated if not NULL and the |
| 1427 | * operation blocks. Will fail with -ENOSYS if not implemented. |
| 1428 | */ |
| 1429 | SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id, |
| 1430 | long, min_nr, |
| 1431 | long, nr, |
| 1432 | struct io_event __user *, events, |
| 1433 | struct timespec __user *, timeout) |
| 1434 | { |
| 1435 | struct kioctx *ioctx = lookup_ioctx(ctx_id); |
| 1436 | long ret = -EINVAL; |
| 1437 | |
| 1438 | if (likely(ioctx)) { |
| 1439 | if (likely(min_nr <= nr && min_nr >= 0)) |
| 1440 | ret = read_events(ioctx, min_nr, nr, events, timeout); |
| 1441 | put_ioctx(ioctx); |
| 1442 | } |
| 1443 | return ret; |
| 1444 | } |