| 1 | /* |
| 2 | * "splice": joining two ropes together by interweaving their strands. |
| 3 | * |
| 4 | * This is the "extended pipe" functionality, where a pipe is used as |
| 5 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel |
| 6 | * buffer that you can use to transfer data from one end to the other. |
| 7 | * |
| 8 | * The traditional unix read/write is extended with a "splice()" operation |
| 9 | * that transfers data buffers to or from a pipe buffer. |
| 10 | * |
| 11 | * Named by Larry McVoy, original implementation from Linus, extended by |
| 12 | * Jens to support splicing to files, network, direct splicing, etc and |
| 13 | * fixing lots of bugs. |
| 14 | * |
| 15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
| 16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
| 17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> |
| 18 | * |
| 19 | */ |
| 20 | #include <linux/fs.h> |
| 21 | #include <linux/file.h> |
| 22 | #include <linux/pagemap.h> |
| 23 | #include <linux/splice.h> |
| 24 | #include <linux/memcontrol.h> |
| 25 | #include <linux/mm_inline.h> |
| 26 | #include <linux/swap.h> |
| 27 | #include <linux/writeback.h> |
| 28 | #include <linux/export.h> |
| 29 | #include <linux/syscalls.h> |
| 30 | #include <linux/uio.h> |
| 31 | #include <linux/security.h> |
| 32 | #include <linux/gfp.h> |
| 33 | #include <linux/socket.h> |
| 34 | #include <linux/compat.h> |
| 35 | #include "internal.h" |
| 36 | |
| 37 | /* |
| 38 | * Attempt to steal a page from a pipe buffer. This should perhaps go into |
| 39 | * a vm helper function, it's already simplified quite a bit by the |
| 40 | * addition of remove_mapping(). If success is returned, the caller may |
| 41 | * attempt to reuse this page for another destination. |
| 42 | */ |
| 43 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
| 44 | struct pipe_buffer *buf) |
| 45 | { |
| 46 | struct page *page = buf->page; |
| 47 | struct address_space *mapping; |
| 48 | |
| 49 | lock_page(page); |
| 50 | |
| 51 | mapping = page_mapping(page); |
| 52 | if (mapping) { |
| 53 | WARN_ON(!PageUptodate(page)); |
| 54 | |
| 55 | /* |
| 56 | * At least for ext2 with nobh option, we need to wait on |
| 57 | * writeback completing on this page, since we'll remove it |
| 58 | * from the pagecache. Otherwise truncate wont wait on the |
| 59 | * page, allowing the disk blocks to be reused by someone else |
| 60 | * before we actually wrote our data to them. fs corruption |
| 61 | * ensues. |
| 62 | */ |
| 63 | wait_on_page_writeback(page); |
| 64 | |
| 65 | if (page_has_private(page) && |
| 66 | !try_to_release_page(page, GFP_KERNEL)) |
| 67 | goto out_unlock; |
| 68 | |
| 69 | /* |
| 70 | * If we succeeded in removing the mapping, set LRU flag |
| 71 | * and return good. |
| 72 | */ |
| 73 | if (remove_mapping(mapping, page)) { |
| 74 | buf->flags |= PIPE_BUF_FLAG_LRU; |
| 75 | return 0; |
| 76 | } |
| 77 | } |
| 78 | |
| 79 | /* |
| 80 | * Raced with truncate or failed to remove page from current |
| 81 | * address space, unlock and return failure. |
| 82 | */ |
| 83 | out_unlock: |
| 84 | unlock_page(page); |
| 85 | return 1; |
| 86 | } |
| 87 | |
| 88 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
| 89 | struct pipe_buffer *buf) |
| 90 | { |
| 91 | page_cache_release(buf->page); |
| 92 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
| 93 | } |
| 94 | |
| 95 | /* |
| 96 | * Check whether the contents of buf is OK to access. Since the content |
| 97 | * is a page cache page, IO may be in flight. |
| 98 | */ |
| 99 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
| 100 | struct pipe_buffer *buf) |
| 101 | { |
| 102 | struct page *page = buf->page; |
| 103 | int err; |
| 104 | |
| 105 | if (!PageUptodate(page)) { |
| 106 | lock_page(page); |
| 107 | |
| 108 | /* |
| 109 | * Page got truncated/unhashed. This will cause a 0-byte |
| 110 | * splice, if this is the first page. |
| 111 | */ |
| 112 | if (!page->mapping) { |
| 113 | err = -ENODATA; |
| 114 | goto error; |
| 115 | } |
| 116 | |
| 117 | /* |
| 118 | * Uh oh, read-error from disk. |
| 119 | */ |
| 120 | if (!PageUptodate(page)) { |
| 121 | err = -EIO; |
| 122 | goto error; |
| 123 | } |
| 124 | |
| 125 | /* |
| 126 | * Page is ok afterall, we are done. |
| 127 | */ |
| 128 | unlock_page(page); |
| 129 | } |
| 130 | |
| 131 | return 0; |
| 132 | error: |
| 133 | unlock_page(page); |
| 134 | return err; |
| 135 | } |
| 136 | |
| 137 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
| 138 | .can_merge = 0, |
| 139 | .confirm = page_cache_pipe_buf_confirm, |
| 140 | .release = page_cache_pipe_buf_release, |
| 141 | .steal = page_cache_pipe_buf_steal, |
| 142 | .get = generic_pipe_buf_get, |
| 143 | }; |
| 144 | |
| 145 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
| 146 | struct pipe_buffer *buf) |
| 147 | { |
| 148 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
| 149 | return 1; |
| 150 | |
| 151 | buf->flags |= PIPE_BUF_FLAG_LRU; |
| 152 | return generic_pipe_buf_steal(pipe, buf); |
| 153 | } |
| 154 | |
| 155 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
| 156 | .can_merge = 0, |
| 157 | .confirm = generic_pipe_buf_confirm, |
| 158 | .release = page_cache_pipe_buf_release, |
| 159 | .steal = user_page_pipe_buf_steal, |
| 160 | .get = generic_pipe_buf_get, |
| 161 | }; |
| 162 | |
| 163 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
| 164 | { |
| 165 | smp_mb(); |
| 166 | if (waitqueue_active(&pipe->wait)) |
| 167 | wake_up_interruptible(&pipe->wait); |
| 168 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
| 169 | } |
| 170 | |
| 171 | /** |
| 172 | * splice_to_pipe - fill passed data into a pipe |
| 173 | * @pipe: pipe to fill |
| 174 | * @spd: data to fill |
| 175 | * |
| 176 | * Description: |
| 177 | * @spd contains a map of pages and len/offset tuples, along with |
| 178 | * the struct pipe_buf_operations associated with these pages. This |
| 179 | * function will link that data to the pipe. |
| 180 | * |
| 181 | */ |
| 182 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
| 183 | struct splice_pipe_desc *spd) |
| 184 | { |
| 185 | unsigned int spd_pages = spd->nr_pages; |
| 186 | int ret, do_wakeup, page_nr; |
| 187 | |
| 188 | ret = 0; |
| 189 | do_wakeup = 0; |
| 190 | page_nr = 0; |
| 191 | |
| 192 | pipe_lock(pipe); |
| 193 | |
| 194 | for (;;) { |
| 195 | if (!pipe->readers) { |
| 196 | send_sig(SIGPIPE, current, 0); |
| 197 | if (!ret) |
| 198 | ret = -EPIPE; |
| 199 | break; |
| 200 | } |
| 201 | |
| 202 | if (pipe->nrbufs < pipe->buffers) { |
| 203 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); |
| 204 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
| 205 | |
| 206 | buf->page = spd->pages[page_nr]; |
| 207 | buf->offset = spd->partial[page_nr].offset; |
| 208 | buf->len = spd->partial[page_nr].len; |
| 209 | buf->private = spd->partial[page_nr].private; |
| 210 | buf->ops = spd->ops; |
| 211 | if (spd->flags & SPLICE_F_GIFT) |
| 212 | buf->flags |= PIPE_BUF_FLAG_GIFT; |
| 213 | |
| 214 | pipe->nrbufs++; |
| 215 | page_nr++; |
| 216 | ret += buf->len; |
| 217 | |
| 218 | if (pipe->files) |
| 219 | do_wakeup = 1; |
| 220 | |
| 221 | if (!--spd->nr_pages) |
| 222 | break; |
| 223 | if (pipe->nrbufs < pipe->buffers) |
| 224 | continue; |
| 225 | |
| 226 | break; |
| 227 | } |
| 228 | |
| 229 | if (spd->flags & SPLICE_F_NONBLOCK) { |
| 230 | if (!ret) |
| 231 | ret = -EAGAIN; |
| 232 | break; |
| 233 | } |
| 234 | |
| 235 | if (signal_pending(current)) { |
| 236 | if (!ret) |
| 237 | ret = -ERESTARTSYS; |
| 238 | break; |
| 239 | } |
| 240 | |
| 241 | if (do_wakeup) { |
| 242 | smp_mb(); |
| 243 | if (waitqueue_active(&pipe->wait)) |
| 244 | wake_up_interruptible_sync(&pipe->wait); |
| 245 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
| 246 | do_wakeup = 0; |
| 247 | } |
| 248 | |
| 249 | pipe->waiting_writers++; |
| 250 | pipe_wait(pipe); |
| 251 | pipe->waiting_writers--; |
| 252 | } |
| 253 | |
| 254 | pipe_unlock(pipe); |
| 255 | |
| 256 | if (do_wakeup) |
| 257 | wakeup_pipe_readers(pipe); |
| 258 | |
| 259 | while (page_nr < spd_pages) |
| 260 | spd->spd_release(spd, page_nr++); |
| 261 | |
| 262 | return ret; |
| 263 | } |
| 264 | EXPORT_SYMBOL_GPL(splice_to_pipe); |
| 265 | |
| 266 | void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
| 267 | { |
| 268 | page_cache_release(spd->pages[i]); |
| 269 | } |
| 270 | |
| 271 | /* |
| 272 | * Check if we need to grow the arrays holding pages and partial page |
| 273 | * descriptions. |
| 274 | */ |
| 275 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
| 276 | { |
| 277 | unsigned int buffers = ACCESS_ONCE(pipe->buffers); |
| 278 | |
| 279 | spd->nr_pages_max = buffers; |
| 280 | if (buffers <= PIPE_DEF_BUFFERS) |
| 281 | return 0; |
| 282 | |
| 283 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); |
| 284 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); |
| 285 | |
| 286 | if (spd->pages && spd->partial) |
| 287 | return 0; |
| 288 | |
| 289 | kfree(spd->pages); |
| 290 | kfree(spd->partial); |
| 291 | return -ENOMEM; |
| 292 | } |
| 293 | |
| 294 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
| 295 | { |
| 296 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
| 297 | return; |
| 298 | |
| 299 | kfree(spd->pages); |
| 300 | kfree(spd->partial); |
| 301 | } |
| 302 | |
| 303 | static int |
| 304 | __generic_file_splice_read(struct file *in, loff_t *ppos, |
| 305 | struct pipe_inode_info *pipe, size_t len, |
| 306 | unsigned int flags) |
| 307 | { |
| 308 | struct address_space *mapping = in->f_mapping; |
| 309 | unsigned int loff, nr_pages, req_pages; |
| 310 | struct page *pages[PIPE_DEF_BUFFERS]; |
| 311 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
| 312 | struct page *page; |
| 313 | pgoff_t index, end_index; |
| 314 | loff_t isize; |
| 315 | int error, page_nr; |
| 316 | struct splice_pipe_desc spd = { |
| 317 | .pages = pages, |
| 318 | .partial = partial, |
| 319 | .nr_pages_max = PIPE_DEF_BUFFERS, |
| 320 | .flags = flags, |
| 321 | .ops = &page_cache_pipe_buf_ops, |
| 322 | .spd_release = spd_release_page, |
| 323 | }; |
| 324 | |
| 325 | if (splice_grow_spd(pipe, &spd)) |
| 326 | return -ENOMEM; |
| 327 | |
| 328 | index = *ppos >> PAGE_CACHE_SHIFT; |
| 329 | loff = *ppos & ~PAGE_CACHE_MASK; |
| 330 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| 331 | nr_pages = min(req_pages, spd.nr_pages_max); |
| 332 | |
| 333 | /* |
| 334 | * Lookup the (hopefully) full range of pages we need. |
| 335 | */ |
| 336 | spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); |
| 337 | index += spd.nr_pages; |
| 338 | |
| 339 | /* |
| 340 | * If find_get_pages_contig() returned fewer pages than we needed, |
| 341 | * readahead/allocate the rest and fill in the holes. |
| 342 | */ |
| 343 | if (spd.nr_pages < nr_pages) |
| 344 | page_cache_sync_readahead(mapping, &in->f_ra, in, |
| 345 | index, req_pages - spd.nr_pages); |
| 346 | |
| 347 | error = 0; |
| 348 | while (spd.nr_pages < nr_pages) { |
| 349 | /* |
| 350 | * Page could be there, find_get_pages_contig() breaks on |
| 351 | * the first hole. |
| 352 | */ |
| 353 | page = find_get_page(mapping, index); |
| 354 | if (!page) { |
| 355 | /* |
| 356 | * page didn't exist, allocate one. |
| 357 | */ |
| 358 | page = page_cache_alloc_cold(mapping); |
| 359 | if (!page) |
| 360 | break; |
| 361 | |
| 362 | error = add_to_page_cache_lru(page, mapping, index, |
| 363 | mapping_gfp_constraint(mapping, GFP_KERNEL)); |
| 364 | if (unlikely(error)) { |
| 365 | page_cache_release(page); |
| 366 | if (error == -EEXIST) |
| 367 | continue; |
| 368 | break; |
| 369 | } |
| 370 | /* |
| 371 | * add_to_page_cache() locks the page, unlock it |
| 372 | * to avoid convoluting the logic below even more. |
| 373 | */ |
| 374 | unlock_page(page); |
| 375 | } |
| 376 | |
| 377 | spd.pages[spd.nr_pages++] = page; |
| 378 | index++; |
| 379 | } |
| 380 | |
| 381 | /* |
| 382 | * Now loop over the map and see if we need to start IO on any |
| 383 | * pages, fill in the partial map, etc. |
| 384 | */ |
| 385 | index = *ppos >> PAGE_CACHE_SHIFT; |
| 386 | nr_pages = spd.nr_pages; |
| 387 | spd.nr_pages = 0; |
| 388 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
| 389 | unsigned int this_len; |
| 390 | |
| 391 | if (!len) |
| 392 | break; |
| 393 | |
| 394 | /* |
| 395 | * this_len is the max we'll use from this page |
| 396 | */ |
| 397 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
| 398 | page = spd.pages[page_nr]; |
| 399 | |
| 400 | if (PageReadahead(page)) |
| 401 | page_cache_async_readahead(mapping, &in->f_ra, in, |
| 402 | page, index, req_pages - page_nr); |
| 403 | |
| 404 | /* |
| 405 | * If the page isn't uptodate, we may need to start io on it |
| 406 | */ |
| 407 | if (!PageUptodate(page)) { |
| 408 | lock_page(page); |
| 409 | |
| 410 | /* |
| 411 | * Page was truncated, or invalidated by the |
| 412 | * filesystem. Redo the find/create, but this time the |
| 413 | * page is kept locked, so there's no chance of another |
| 414 | * race with truncate/invalidate. |
| 415 | */ |
| 416 | if (!page->mapping) { |
| 417 | unlock_page(page); |
| 418 | retry_lookup: |
| 419 | page = find_or_create_page(mapping, index, |
| 420 | mapping_gfp_mask(mapping)); |
| 421 | |
| 422 | if (!page) { |
| 423 | error = -ENOMEM; |
| 424 | break; |
| 425 | } |
| 426 | page_cache_release(spd.pages[page_nr]); |
| 427 | spd.pages[page_nr] = page; |
| 428 | } |
| 429 | /* |
| 430 | * page was already under io and is now done, great |
| 431 | */ |
| 432 | if (PageUptodate(page)) { |
| 433 | unlock_page(page); |
| 434 | goto fill_it; |
| 435 | } |
| 436 | |
| 437 | /* |
| 438 | * need to read in the page |
| 439 | */ |
| 440 | error = mapping->a_ops->readpage(in, page); |
| 441 | if (unlikely(error)) { |
| 442 | /* |
| 443 | * Re-lookup the page |
| 444 | */ |
| 445 | if (error == AOP_TRUNCATED_PAGE) |
| 446 | goto retry_lookup; |
| 447 | |
| 448 | break; |
| 449 | } |
| 450 | } |
| 451 | fill_it: |
| 452 | /* |
| 453 | * i_size must be checked after PageUptodate. |
| 454 | */ |
| 455 | isize = i_size_read(mapping->host); |
| 456 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
| 457 | if (unlikely(!isize || index > end_index)) |
| 458 | break; |
| 459 | |
| 460 | /* |
| 461 | * if this is the last page, see if we need to shrink |
| 462 | * the length and stop |
| 463 | */ |
| 464 | if (end_index == index) { |
| 465 | unsigned int plen; |
| 466 | |
| 467 | /* |
| 468 | * max good bytes in this page |
| 469 | */ |
| 470 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
| 471 | if (plen <= loff) |
| 472 | break; |
| 473 | |
| 474 | /* |
| 475 | * force quit after adding this page |
| 476 | */ |
| 477 | this_len = min(this_len, plen - loff); |
| 478 | len = this_len; |
| 479 | } |
| 480 | |
| 481 | spd.partial[page_nr].offset = loff; |
| 482 | spd.partial[page_nr].len = this_len; |
| 483 | len -= this_len; |
| 484 | loff = 0; |
| 485 | spd.nr_pages++; |
| 486 | index++; |
| 487 | } |
| 488 | |
| 489 | /* |
| 490 | * Release any pages at the end, if we quit early. 'page_nr' is how far |
| 491 | * we got, 'nr_pages' is how many pages are in the map. |
| 492 | */ |
| 493 | while (page_nr < nr_pages) |
| 494 | page_cache_release(spd.pages[page_nr++]); |
| 495 | in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
| 496 | |
| 497 | if (spd.nr_pages) |
| 498 | error = splice_to_pipe(pipe, &spd); |
| 499 | |
| 500 | splice_shrink_spd(&spd); |
| 501 | return error; |
| 502 | } |
| 503 | |
| 504 | /** |
| 505 | * generic_file_splice_read - splice data from file to a pipe |
| 506 | * @in: file to splice from |
| 507 | * @ppos: position in @in |
| 508 | * @pipe: pipe to splice to |
| 509 | * @len: number of bytes to splice |
| 510 | * @flags: splice modifier flags |
| 511 | * |
| 512 | * Description: |
| 513 | * Will read pages from given file and fill them into a pipe. Can be |
| 514 | * used as long as the address_space operations for the source implements |
| 515 | * a readpage() hook. |
| 516 | * |
| 517 | */ |
| 518 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
| 519 | struct pipe_inode_info *pipe, size_t len, |
| 520 | unsigned int flags) |
| 521 | { |
| 522 | loff_t isize, left; |
| 523 | int ret; |
| 524 | |
| 525 | if (IS_DAX(in->f_mapping->host)) |
| 526 | return default_file_splice_read(in, ppos, pipe, len, flags); |
| 527 | |
| 528 | isize = i_size_read(in->f_mapping->host); |
| 529 | if (unlikely(*ppos >= isize)) |
| 530 | return 0; |
| 531 | |
| 532 | left = isize - *ppos; |
| 533 | if (unlikely(left < len)) |
| 534 | len = left; |
| 535 | |
| 536 | ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
| 537 | if (ret > 0) { |
| 538 | *ppos += ret; |
| 539 | file_accessed(in); |
| 540 | } |
| 541 | |
| 542 | return ret; |
| 543 | } |
| 544 | EXPORT_SYMBOL(generic_file_splice_read); |
| 545 | |
| 546 | static const struct pipe_buf_operations default_pipe_buf_ops = { |
| 547 | .can_merge = 0, |
| 548 | .confirm = generic_pipe_buf_confirm, |
| 549 | .release = generic_pipe_buf_release, |
| 550 | .steal = generic_pipe_buf_steal, |
| 551 | .get = generic_pipe_buf_get, |
| 552 | }; |
| 553 | |
| 554 | static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe, |
| 555 | struct pipe_buffer *buf) |
| 556 | { |
| 557 | return 1; |
| 558 | } |
| 559 | |
| 560 | /* Pipe buffer operations for a socket and similar. */ |
| 561 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { |
| 562 | .can_merge = 0, |
| 563 | .confirm = generic_pipe_buf_confirm, |
| 564 | .release = generic_pipe_buf_release, |
| 565 | .steal = generic_pipe_buf_nosteal, |
| 566 | .get = generic_pipe_buf_get, |
| 567 | }; |
| 568 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); |
| 569 | |
| 570 | static ssize_t kernel_readv(struct file *file, const struct iovec *vec, |
| 571 | unsigned long vlen, loff_t offset) |
| 572 | { |
| 573 | mm_segment_t old_fs; |
| 574 | loff_t pos = offset; |
| 575 | ssize_t res; |
| 576 | |
| 577 | old_fs = get_fs(); |
| 578 | set_fs(get_ds()); |
| 579 | /* The cast to a user pointer is valid due to the set_fs() */ |
| 580 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos); |
| 581 | set_fs(old_fs); |
| 582 | |
| 583 | return res; |
| 584 | } |
| 585 | |
| 586 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
| 587 | loff_t pos) |
| 588 | { |
| 589 | mm_segment_t old_fs; |
| 590 | ssize_t res; |
| 591 | |
| 592 | old_fs = get_fs(); |
| 593 | set_fs(get_ds()); |
| 594 | /* The cast to a user pointer is valid due to the set_fs() */ |
| 595 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); |
| 596 | set_fs(old_fs); |
| 597 | |
| 598 | return res; |
| 599 | } |
| 600 | EXPORT_SYMBOL(kernel_write); |
| 601 | |
| 602 | ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
| 603 | struct pipe_inode_info *pipe, size_t len, |
| 604 | unsigned int flags) |
| 605 | { |
| 606 | unsigned int nr_pages; |
| 607 | unsigned int nr_freed; |
| 608 | size_t offset; |
| 609 | struct page *pages[PIPE_DEF_BUFFERS]; |
| 610 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
| 611 | struct iovec *vec, __vec[PIPE_DEF_BUFFERS]; |
| 612 | ssize_t res; |
| 613 | size_t this_len; |
| 614 | int error; |
| 615 | int i; |
| 616 | struct splice_pipe_desc spd = { |
| 617 | .pages = pages, |
| 618 | .partial = partial, |
| 619 | .nr_pages_max = PIPE_DEF_BUFFERS, |
| 620 | .flags = flags, |
| 621 | .ops = &default_pipe_buf_ops, |
| 622 | .spd_release = spd_release_page, |
| 623 | }; |
| 624 | |
| 625 | if (splice_grow_spd(pipe, &spd)) |
| 626 | return -ENOMEM; |
| 627 | |
| 628 | res = -ENOMEM; |
| 629 | vec = __vec; |
| 630 | if (spd.nr_pages_max > PIPE_DEF_BUFFERS) { |
| 631 | vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL); |
| 632 | if (!vec) |
| 633 | goto shrink_ret; |
| 634 | } |
| 635 | |
| 636 | offset = *ppos & ~PAGE_CACHE_MASK; |
| 637 | nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| 638 | |
| 639 | for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) { |
| 640 | struct page *page; |
| 641 | |
| 642 | page = alloc_page(GFP_USER); |
| 643 | error = -ENOMEM; |
| 644 | if (!page) |
| 645 | goto err; |
| 646 | |
| 647 | this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); |
| 648 | vec[i].iov_base = (void __user *) page_address(page); |
| 649 | vec[i].iov_len = this_len; |
| 650 | spd.pages[i] = page; |
| 651 | spd.nr_pages++; |
| 652 | len -= this_len; |
| 653 | offset = 0; |
| 654 | } |
| 655 | |
| 656 | res = kernel_readv(in, vec, spd.nr_pages, *ppos); |
| 657 | if (res < 0) { |
| 658 | error = res; |
| 659 | goto err; |
| 660 | } |
| 661 | |
| 662 | error = 0; |
| 663 | if (!res) |
| 664 | goto err; |
| 665 | |
| 666 | nr_freed = 0; |
| 667 | for (i = 0; i < spd.nr_pages; i++) { |
| 668 | this_len = min_t(size_t, vec[i].iov_len, res); |
| 669 | spd.partial[i].offset = 0; |
| 670 | spd.partial[i].len = this_len; |
| 671 | if (!this_len) { |
| 672 | __free_page(spd.pages[i]); |
| 673 | spd.pages[i] = NULL; |
| 674 | nr_freed++; |
| 675 | } |
| 676 | res -= this_len; |
| 677 | } |
| 678 | spd.nr_pages -= nr_freed; |
| 679 | |
| 680 | res = splice_to_pipe(pipe, &spd); |
| 681 | if (res > 0) |
| 682 | *ppos += res; |
| 683 | |
| 684 | shrink_ret: |
| 685 | if (vec != __vec) |
| 686 | kfree(vec); |
| 687 | splice_shrink_spd(&spd); |
| 688 | return res; |
| 689 | |
| 690 | err: |
| 691 | for (i = 0; i < spd.nr_pages; i++) |
| 692 | __free_page(spd.pages[i]); |
| 693 | |
| 694 | res = error; |
| 695 | goto shrink_ret; |
| 696 | } |
| 697 | EXPORT_SYMBOL(default_file_splice_read); |
| 698 | |
| 699 | /* |
| 700 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
| 701 | * using sendpage(). Return the number of bytes sent. |
| 702 | */ |
| 703 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
| 704 | struct pipe_buffer *buf, struct splice_desc *sd) |
| 705 | { |
| 706 | struct file *file = sd->u.file; |
| 707 | loff_t pos = sd->pos; |
| 708 | int more; |
| 709 | |
| 710 | if (!likely(file->f_op->sendpage)) |
| 711 | return -EINVAL; |
| 712 | |
| 713 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
| 714 | |
| 715 | if (sd->len < sd->total_len && pipe->nrbufs > 1) |
| 716 | more |= MSG_SENDPAGE_NOTLAST; |
| 717 | |
| 718 | return file->f_op->sendpage(file, buf->page, buf->offset, |
| 719 | sd->len, &pos, more); |
| 720 | } |
| 721 | |
| 722 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
| 723 | { |
| 724 | smp_mb(); |
| 725 | if (waitqueue_active(&pipe->wait)) |
| 726 | wake_up_interruptible(&pipe->wait); |
| 727 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
| 728 | } |
| 729 | |
| 730 | /** |
| 731 | * splice_from_pipe_feed - feed available data from a pipe to a file |
| 732 | * @pipe: pipe to splice from |
| 733 | * @sd: information to @actor |
| 734 | * @actor: handler that splices the data |
| 735 | * |
| 736 | * Description: |
| 737 | * This function loops over the pipe and calls @actor to do the |
| 738 | * actual moving of a single struct pipe_buffer to the desired |
| 739 | * destination. It returns when there's no more buffers left in |
| 740 | * the pipe or if the requested number of bytes (@sd->total_len) |
| 741 | * have been copied. It returns a positive number (one) if the |
| 742 | * pipe needs to be filled with more data, zero if the required |
| 743 | * number of bytes have been copied and -errno on error. |
| 744 | * |
| 745 | * This, together with splice_from_pipe_{begin,end,next}, may be |
| 746 | * used to implement the functionality of __splice_from_pipe() when |
| 747 | * locking is required around copying the pipe buffers to the |
| 748 | * destination. |
| 749 | */ |
| 750 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
| 751 | splice_actor *actor) |
| 752 | { |
| 753 | int ret; |
| 754 | |
| 755 | while (pipe->nrbufs) { |
| 756 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
| 757 | const struct pipe_buf_operations *ops = buf->ops; |
| 758 | |
| 759 | sd->len = buf->len; |
| 760 | if (sd->len > sd->total_len) |
| 761 | sd->len = sd->total_len; |
| 762 | |
| 763 | ret = buf->ops->confirm(pipe, buf); |
| 764 | if (unlikely(ret)) { |
| 765 | if (ret == -ENODATA) |
| 766 | ret = 0; |
| 767 | return ret; |
| 768 | } |
| 769 | |
| 770 | ret = actor(pipe, buf, sd); |
| 771 | if (ret <= 0) |
| 772 | return ret; |
| 773 | |
| 774 | buf->offset += ret; |
| 775 | buf->len -= ret; |
| 776 | |
| 777 | sd->num_spliced += ret; |
| 778 | sd->len -= ret; |
| 779 | sd->pos += ret; |
| 780 | sd->total_len -= ret; |
| 781 | |
| 782 | if (!buf->len) { |
| 783 | buf->ops = NULL; |
| 784 | ops->release(pipe, buf); |
| 785 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
| 786 | pipe->nrbufs--; |
| 787 | if (pipe->files) |
| 788 | sd->need_wakeup = true; |
| 789 | } |
| 790 | |
| 791 | if (!sd->total_len) |
| 792 | return 0; |
| 793 | } |
| 794 | |
| 795 | return 1; |
| 796 | } |
| 797 | |
| 798 | /** |
| 799 | * splice_from_pipe_next - wait for some data to splice from |
| 800 | * @pipe: pipe to splice from |
| 801 | * @sd: information about the splice operation |
| 802 | * |
| 803 | * Description: |
| 804 | * This function will wait for some data and return a positive |
| 805 | * value (one) if pipe buffers are available. It will return zero |
| 806 | * or -errno if no more data needs to be spliced. |
| 807 | */ |
| 808 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
| 809 | { |
| 810 | /* |
| 811 | * Check for signal early to make process killable when there are |
| 812 | * always buffers available |
| 813 | */ |
| 814 | if (signal_pending(current)) |
| 815 | return -ERESTARTSYS; |
| 816 | |
| 817 | while (!pipe->nrbufs) { |
| 818 | if (!pipe->writers) |
| 819 | return 0; |
| 820 | |
| 821 | if (!pipe->waiting_writers && sd->num_spliced) |
| 822 | return 0; |
| 823 | |
| 824 | if (sd->flags & SPLICE_F_NONBLOCK) |
| 825 | return -EAGAIN; |
| 826 | |
| 827 | if (signal_pending(current)) |
| 828 | return -ERESTARTSYS; |
| 829 | |
| 830 | if (sd->need_wakeup) { |
| 831 | wakeup_pipe_writers(pipe); |
| 832 | sd->need_wakeup = false; |
| 833 | } |
| 834 | |
| 835 | pipe_wait(pipe); |
| 836 | } |
| 837 | |
| 838 | return 1; |
| 839 | } |
| 840 | |
| 841 | /** |
| 842 | * splice_from_pipe_begin - start splicing from pipe |
| 843 | * @sd: information about the splice operation |
| 844 | * |
| 845 | * Description: |
| 846 | * This function should be called before a loop containing |
| 847 | * splice_from_pipe_next() and splice_from_pipe_feed() to |
| 848 | * initialize the necessary fields of @sd. |
| 849 | */ |
| 850 | static void splice_from_pipe_begin(struct splice_desc *sd) |
| 851 | { |
| 852 | sd->num_spliced = 0; |
| 853 | sd->need_wakeup = false; |
| 854 | } |
| 855 | |
| 856 | /** |
| 857 | * splice_from_pipe_end - finish splicing from pipe |
| 858 | * @pipe: pipe to splice from |
| 859 | * @sd: information about the splice operation |
| 860 | * |
| 861 | * Description: |
| 862 | * This function will wake up pipe writers if necessary. It should |
| 863 | * be called after a loop containing splice_from_pipe_next() and |
| 864 | * splice_from_pipe_feed(). |
| 865 | */ |
| 866 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
| 867 | { |
| 868 | if (sd->need_wakeup) |
| 869 | wakeup_pipe_writers(pipe); |
| 870 | } |
| 871 | |
| 872 | /** |
| 873 | * __splice_from_pipe - splice data from a pipe to given actor |
| 874 | * @pipe: pipe to splice from |
| 875 | * @sd: information to @actor |
| 876 | * @actor: handler that splices the data |
| 877 | * |
| 878 | * Description: |
| 879 | * This function does little more than loop over the pipe and call |
| 880 | * @actor to do the actual moving of a single struct pipe_buffer to |
| 881 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or |
| 882 | * pipe_to_user. |
| 883 | * |
| 884 | */ |
| 885 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
| 886 | splice_actor *actor) |
| 887 | { |
| 888 | int ret; |
| 889 | |
| 890 | splice_from_pipe_begin(sd); |
| 891 | do { |
| 892 | cond_resched(); |
| 893 | ret = splice_from_pipe_next(pipe, sd); |
| 894 | if (ret > 0) |
| 895 | ret = splice_from_pipe_feed(pipe, sd, actor); |
| 896 | } while (ret > 0); |
| 897 | splice_from_pipe_end(pipe, sd); |
| 898 | |
| 899 | return sd->num_spliced ? sd->num_spliced : ret; |
| 900 | } |
| 901 | EXPORT_SYMBOL(__splice_from_pipe); |
| 902 | |
| 903 | /** |
| 904 | * splice_from_pipe - splice data from a pipe to a file |
| 905 | * @pipe: pipe to splice from |
| 906 | * @out: file to splice to |
| 907 | * @ppos: position in @out |
| 908 | * @len: how many bytes to splice |
| 909 | * @flags: splice modifier flags |
| 910 | * @actor: handler that splices the data |
| 911 | * |
| 912 | * Description: |
| 913 | * See __splice_from_pipe. This function locks the pipe inode, |
| 914 | * otherwise it's identical to __splice_from_pipe(). |
| 915 | * |
| 916 | */ |
| 917 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
| 918 | loff_t *ppos, size_t len, unsigned int flags, |
| 919 | splice_actor *actor) |
| 920 | { |
| 921 | ssize_t ret; |
| 922 | struct splice_desc sd = { |
| 923 | .total_len = len, |
| 924 | .flags = flags, |
| 925 | .pos = *ppos, |
| 926 | .u.file = out, |
| 927 | }; |
| 928 | |
| 929 | pipe_lock(pipe); |
| 930 | ret = __splice_from_pipe(pipe, &sd, actor); |
| 931 | pipe_unlock(pipe); |
| 932 | |
| 933 | return ret; |
| 934 | } |
| 935 | |
| 936 | /** |
| 937 | * iter_file_splice_write - splice data from a pipe to a file |
| 938 | * @pipe: pipe info |
| 939 | * @out: file to write to |
| 940 | * @ppos: position in @out |
| 941 | * @len: number of bytes to splice |
| 942 | * @flags: splice modifier flags |
| 943 | * |
| 944 | * Description: |
| 945 | * Will either move or copy pages (determined by @flags options) from |
| 946 | * the given pipe inode to the given file. |
| 947 | * This one is ->write_iter-based. |
| 948 | * |
| 949 | */ |
| 950 | ssize_t |
| 951 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, |
| 952 | loff_t *ppos, size_t len, unsigned int flags) |
| 953 | { |
| 954 | struct splice_desc sd = { |
| 955 | .total_len = len, |
| 956 | .flags = flags, |
| 957 | .pos = *ppos, |
| 958 | .u.file = out, |
| 959 | }; |
| 960 | int nbufs = pipe->buffers; |
| 961 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), |
| 962 | GFP_KERNEL); |
| 963 | ssize_t ret; |
| 964 | |
| 965 | if (unlikely(!array)) |
| 966 | return -ENOMEM; |
| 967 | |
| 968 | pipe_lock(pipe); |
| 969 | |
| 970 | splice_from_pipe_begin(&sd); |
| 971 | while (sd.total_len) { |
| 972 | struct iov_iter from; |
| 973 | size_t left; |
| 974 | int n, idx; |
| 975 | |
| 976 | ret = splice_from_pipe_next(pipe, &sd); |
| 977 | if (ret <= 0) |
| 978 | break; |
| 979 | |
| 980 | if (unlikely(nbufs < pipe->buffers)) { |
| 981 | kfree(array); |
| 982 | nbufs = pipe->buffers; |
| 983 | array = kcalloc(nbufs, sizeof(struct bio_vec), |
| 984 | GFP_KERNEL); |
| 985 | if (!array) { |
| 986 | ret = -ENOMEM; |
| 987 | break; |
| 988 | } |
| 989 | } |
| 990 | |
| 991 | /* build the vector */ |
| 992 | left = sd.total_len; |
| 993 | for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) { |
| 994 | struct pipe_buffer *buf = pipe->bufs + idx; |
| 995 | size_t this_len = buf->len; |
| 996 | |
| 997 | if (this_len > left) |
| 998 | this_len = left; |
| 999 | |
| 1000 | if (idx == pipe->buffers - 1) |
| 1001 | idx = -1; |
| 1002 | |
| 1003 | ret = buf->ops->confirm(pipe, buf); |
| 1004 | if (unlikely(ret)) { |
| 1005 | if (ret == -ENODATA) |
| 1006 | ret = 0; |
| 1007 | goto done; |
| 1008 | } |
| 1009 | |
| 1010 | array[n].bv_page = buf->page; |
| 1011 | array[n].bv_len = this_len; |
| 1012 | array[n].bv_offset = buf->offset; |
| 1013 | left -= this_len; |
| 1014 | } |
| 1015 | |
| 1016 | iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n, |
| 1017 | sd.total_len - left); |
| 1018 | ret = vfs_iter_write(out, &from, &sd.pos); |
| 1019 | if (ret <= 0) |
| 1020 | break; |
| 1021 | |
| 1022 | sd.num_spliced += ret; |
| 1023 | sd.total_len -= ret; |
| 1024 | *ppos = sd.pos; |
| 1025 | |
| 1026 | /* dismiss the fully eaten buffers, adjust the partial one */ |
| 1027 | while (ret) { |
| 1028 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
| 1029 | if (ret >= buf->len) { |
| 1030 | const struct pipe_buf_operations *ops = buf->ops; |
| 1031 | ret -= buf->len; |
| 1032 | buf->len = 0; |
| 1033 | buf->ops = NULL; |
| 1034 | ops->release(pipe, buf); |
| 1035 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
| 1036 | pipe->nrbufs--; |
| 1037 | if (pipe->files) |
| 1038 | sd.need_wakeup = true; |
| 1039 | } else { |
| 1040 | buf->offset += ret; |
| 1041 | buf->len -= ret; |
| 1042 | ret = 0; |
| 1043 | } |
| 1044 | } |
| 1045 | } |
| 1046 | done: |
| 1047 | kfree(array); |
| 1048 | splice_from_pipe_end(pipe, &sd); |
| 1049 | |
| 1050 | pipe_unlock(pipe); |
| 1051 | |
| 1052 | if (sd.num_spliced) |
| 1053 | ret = sd.num_spliced; |
| 1054 | |
| 1055 | return ret; |
| 1056 | } |
| 1057 | |
| 1058 | EXPORT_SYMBOL(iter_file_splice_write); |
| 1059 | |
| 1060 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
| 1061 | struct splice_desc *sd) |
| 1062 | { |
| 1063 | int ret; |
| 1064 | void *data; |
| 1065 | loff_t tmp = sd->pos; |
| 1066 | |
| 1067 | data = kmap(buf->page); |
| 1068 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); |
| 1069 | kunmap(buf->page); |
| 1070 | |
| 1071 | return ret; |
| 1072 | } |
| 1073 | |
| 1074 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, |
| 1075 | struct file *out, loff_t *ppos, |
| 1076 | size_t len, unsigned int flags) |
| 1077 | { |
| 1078 | ssize_t ret; |
| 1079 | |
| 1080 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
| 1081 | if (ret > 0) |
| 1082 | *ppos += ret; |
| 1083 | |
| 1084 | return ret; |
| 1085 | } |
| 1086 | |
| 1087 | /** |
| 1088 | * generic_splice_sendpage - splice data from a pipe to a socket |
| 1089 | * @pipe: pipe to splice from |
| 1090 | * @out: socket to write to |
| 1091 | * @ppos: position in @out |
| 1092 | * @len: number of bytes to splice |
| 1093 | * @flags: splice modifier flags |
| 1094 | * |
| 1095 | * Description: |
| 1096 | * Will send @len bytes from the pipe to a network socket. No data copying |
| 1097 | * is involved. |
| 1098 | * |
| 1099 | */ |
| 1100 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
| 1101 | loff_t *ppos, size_t len, unsigned int flags) |
| 1102 | { |
| 1103 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
| 1104 | } |
| 1105 | |
| 1106 | EXPORT_SYMBOL(generic_splice_sendpage); |
| 1107 | |
| 1108 | /* |
| 1109 | * Attempt to initiate a splice from pipe to file. |
| 1110 | */ |
| 1111 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
| 1112 | loff_t *ppos, size_t len, unsigned int flags) |
| 1113 | { |
| 1114 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
| 1115 | loff_t *, size_t, unsigned int); |
| 1116 | |
| 1117 | if (out->f_op->splice_write) |
| 1118 | splice_write = out->f_op->splice_write; |
| 1119 | else |
| 1120 | splice_write = default_file_splice_write; |
| 1121 | |
| 1122 | return splice_write(pipe, out, ppos, len, flags); |
| 1123 | } |
| 1124 | |
| 1125 | /* |
| 1126 | * Attempt to initiate a splice from a file to a pipe. |
| 1127 | */ |
| 1128 | static long do_splice_to(struct file *in, loff_t *ppos, |
| 1129 | struct pipe_inode_info *pipe, size_t len, |
| 1130 | unsigned int flags) |
| 1131 | { |
| 1132 | ssize_t (*splice_read)(struct file *, loff_t *, |
| 1133 | struct pipe_inode_info *, size_t, unsigned int); |
| 1134 | int ret; |
| 1135 | |
| 1136 | if (unlikely(!(in->f_mode & FMODE_READ))) |
| 1137 | return -EBADF; |
| 1138 | |
| 1139 | ret = rw_verify_area(READ, in, ppos, len); |
| 1140 | if (unlikely(ret < 0)) |
| 1141 | return ret; |
| 1142 | |
| 1143 | if (in->f_op->splice_read) |
| 1144 | splice_read = in->f_op->splice_read; |
| 1145 | else |
| 1146 | splice_read = default_file_splice_read; |
| 1147 | |
| 1148 | return splice_read(in, ppos, pipe, len, flags); |
| 1149 | } |
| 1150 | |
| 1151 | /** |
| 1152 | * splice_direct_to_actor - splices data directly between two non-pipes |
| 1153 | * @in: file to splice from |
| 1154 | * @sd: actor information on where to splice to |
| 1155 | * @actor: handles the data splicing |
| 1156 | * |
| 1157 | * Description: |
| 1158 | * This is a special case helper to splice directly between two |
| 1159 | * points, without requiring an explicit pipe. Internally an allocated |
| 1160 | * pipe is cached in the process, and reused during the lifetime of |
| 1161 | * that process. |
| 1162 | * |
| 1163 | */ |
| 1164 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, |
| 1165 | splice_direct_actor *actor) |
| 1166 | { |
| 1167 | struct pipe_inode_info *pipe; |
| 1168 | long ret, bytes; |
| 1169 | umode_t i_mode; |
| 1170 | size_t len; |
| 1171 | int i, flags, more; |
| 1172 | |
| 1173 | /* |
| 1174 | * We require the input being a regular file, as we don't want to |
| 1175 | * randomly drop data for eg socket -> socket splicing. Use the |
| 1176 | * piped splicing for that! |
| 1177 | */ |
| 1178 | i_mode = file_inode(in)->i_mode; |
| 1179 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
| 1180 | return -EINVAL; |
| 1181 | |
| 1182 | /* |
| 1183 | * neither in nor out is a pipe, setup an internal pipe attached to |
| 1184 | * 'out' and transfer the wanted data from 'in' to 'out' through that |
| 1185 | */ |
| 1186 | pipe = current->splice_pipe; |
| 1187 | if (unlikely(!pipe)) { |
| 1188 | pipe = alloc_pipe_info(); |
| 1189 | if (!pipe) |
| 1190 | return -ENOMEM; |
| 1191 | |
| 1192 | /* |
| 1193 | * We don't have an immediate reader, but we'll read the stuff |
| 1194 | * out of the pipe right after the splice_to_pipe(). So set |
| 1195 | * PIPE_READERS appropriately. |
| 1196 | */ |
| 1197 | pipe->readers = 1; |
| 1198 | |
| 1199 | current->splice_pipe = pipe; |
| 1200 | } |
| 1201 | |
| 1202 | /* |
| 1203 | * Do the splice. |
| 1204 | */ |
| 1205 | ret = 0; |
| 1206 | bytes = 0; |
| 1207 | len = sd->total_len; |
| 1208 | flags = sd->flags; |
| 1209 | |
| 1210 | /* |
| 1211 | * Don't block on output, we have to drain the direct pipe. |
| 1212 | */ |
| 1213 | sd->flags &= ~SPLICE_F_NONBLOCK; |
| 1214 | more = sd->flags & SPLICE_F_MORE; |
| 1215 | |
| 1216 | while (len) { |
| 1217 | size_t read_len; |
| 1218 | loff_t pos = sd->pos, prev_pos = pos; |
| 1219 | |
| 1220 | ret = do_splice_to(in, &pos, pipe, len, flags); |
| 1221 | if (unlikely(ret <= 0)) |
| 1222 | goto out_release; |
| 1223 | |
| 1224 | read_len = ret; |
| 1225 | sd->total_len = read_len; |
| 1226 | |
| 1227 | /* |
| 1228 | * If more data is pending, set SPLICE_F_MORE |
| 1229 | * If this is the last data and SPLICE_F_MORE was not set |
| 1230 | * initially, clears it. |
| 1231 | */ |
| 1232 | if (read_len < len) |
| 1233 | sd->flags |= SPLICE_F_MORE; |
| 1234 | else if (!more) |
| 1235 | sd->flags &= ~SPLICE_F_MORE; |
| 1236 | /* |
| 1237 | * NOTE: nonblocking mode only applies to the input. We |
| 1238 | * must not do the output in nonblocking mode as then we |
| 1239 | * could get stuck data in the internal pipe: |
| 1240 | */ |
| 1241 | ret = actor(pipe, sd); |
| 1242 | if (unlikely(ret <= 0)) { |
| 1243 | sd->pos = prev_pos; |
| 1244 | goto out_release; |
| 1245 | } |
| 1246 | |
| 1247 | bytes += ret; |
| 1248 | len -= ret; |
| 1249 | sd->pos = pos; |
| 1250 | |
| 1251 | if (ret < read_len) { |
| 1252 | sd->pos = prev_pos + ret; |
| 1253 | goto out_release; |
| 1254 | } |
| 1255 | } |
| 1256 | |
| 1257 | done: |
| 1258 | pipe->nrbufs = pipe->curbuf = 0; |
| 1259 | file_accessed(in); |
| 1260 | return bytes; |
| 1261 | |
| 1262 | out_release: |
| 1263 | /* |
| 1264 | * If we did an incomplete transfer we must release |
| 1265 | * the pipe buffers in question: |
| 1266 | */ |
| 1267 | for (i = 0; i < pipe->buffers; i++) { |
| 1268 | struct pipe_buffer *buf = pipe->bufs + i; |
| 1269 | |
| 1270 | if (buf->ops) { |
| 1271 | buf->ops->release(pipe, buf); |
| 1272 | buf->ops = NULL; |
| 1273 | } |
| 1274 | } |
| 1275 | |
| 1276 | if (!bytes) |
| 1277 | bytes = ret; |
| 1278 | |
| 1279 | goto done; |
| 1280 | } |
| 1281 | EXPORT_SYMBOL(splice_direct_to_actor); |
| 1282 | |
| 1283 | static int direct_splice_actor(struct pipe_inode_info *pipe, |
| 1284 | struct splice_desc *sd) |
| 1285 | { |
| 1286 | struct file *file = sd->u.file; |
| 1287 | |
| 1288 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
| 1289 | sd->flags); |
| 1290 | } |
| 1291 | |
| 1292 | /** |
| 1293 | * do_splice_direct - splices data directly between two files |
| 1294 | * @in: file to splice from |
| 1295 | * @ppos: input file offset |
| 1296 | * @out: file to splice to |
| 1297 | * @opos: output file offset |
| 1298 | * @len: number of bytes to splice |
| 1299 | * @flags: splice modifier flags |
| 1300 | * |
| 1301 | * Description: |
| 1302 | * For use by do_sendfile(). splice can easily emulate sendfile, but |
| 1303 | * doing it in the application would incur an extra system call |
| 1304 | * (splice in + splice out, as compared to just sendfile()). So this helper |
| 1305 | * can splice directly through a process-private pipe. |
| 1306 | * |
| 1307 | */ |
| 1308 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
| 1309 | loff_t *opos, size_t len, unsigned int flags) |
| 1310 | { |
| 1311 | struct splice_desc sd = { |
| 1312 | .len = len, |
| 1313 | .total_len = len, |
| 1314 | .flags = flags, |
| 1315 | .pos = *ppos, |
| 1316 | .u.file = out, |
| 1317 | .opos = opos, |
| 1318 | }; |
| 1319 | long ret; |
| 1320 | |
| 1321 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
| 1322 | return -EBADF; |
| 1323 | |
| 1324 | if (unlikely(out->f_flags & O_APPEND)) |
| 1325 | return -EINVAL; |
| 1326 | |
| 1327 | ret = rw_verify_area(WRITE, out, opos, len); |
| 1328 | if (unlikely(ret < 0)) |
| 1329 | return ret; |
| 1330 | |
| 1331 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
| 1332 | if (ret > 0) |
| 1333 | *ppos = sd.pos; |
| 1334 | |
| 1335 | return ret; |
| 1336 | } |
| 1337 | EXPORT_SYMBOL(do_splice_direct); |
| 1338 | |
| 1339 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
| 1340 | struct pipe_inode_info *opipe, |
| 1341 | size_t len, unsigned int flags); |
| 1342 | |
| 1343 | /* |
| 1344 | * Determine where to splice to/from. |
| 1345 | */ |
| 1346 | static long do_splice(struct file *in, loff_t __user *off_in, |
| 1347 | struct file *out, loff_t __user *off_out, |
| 1348 | size_t len, unsigned int flags) |
| 1349 | { |
| 1350 | struct pipe_inode_info *ipipe; |
| 1351 | struct pipe_inode_info *opipe; |
| 1352 | loff_t offset; |
| 1353 | long ret; |
| 1354 | |
| 1355 | ipipe = get_pipe_info(in); |
| 1356 | opipe = get_pipe_info(out); |
| 1357 | |
| 1358 | if (ipipe && opipe) { |
| 1359 | if (off_in || off_out) |
| 1360 | return -ESPIPE; |
| 1361 | |
| 1362 | if (!(in->f_mode & FMODE_READ)) |
| 1363 | return -EBADF; |
| 1364 | |
| 1365 | if (!(out->f_mode & FMODE_WRITE)) |
| 1366 | return -EBADF; |
| 1367 | |
| 1368 | /* Splicing to self would be fun, but... */ |
| 1369 | if (ipipe == opipe) |
| 1370 | return -EINVAL; |
| 1371 | |
| 1372 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
| 1373 | } |
| 1374 | |
| 1375 | if (ipipe) { |
| 1376 | if (off_in) |
| 1377 | return -ESPIPE; |
| 1378 | if (off_out) { |
| 1379 | if (!(out->f_mode & FMODE_PWRITE)) |
| 1380 | return -EINVAL; |
| 1381 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
| 1382 | return -EFAULT; |
| 1383 | } else { |
| 1384 | offset = out->f_pos; |
| 1385 | } |
| 1386 | |
| 1387 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
| 1388 | return -EBADF; |
| 1389 | |
| 1390 | if (unlikely(out->f_flags & O_APPEND)) |
| 1391 | return -EINVAL; |
| 1392 | |
| 1393 | ret = rw_verify_area(WRITE, out, &offset, len); |
| 1394 | if (unlikely(ret < 0)) |
| 1395 | return ret; |
| 1396 | |
| 1397 | file_start_write(out); |
| 1398 | ret = do_splice_from(ipipe, out, &offset, len, flags); |
| 1399 | file_end_write(out); |
| 1400 | |
| 1401 | if (!off_out) |
| 1402 | out->f_pos = offset; |
| 1403 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) |
| 1404 | ret = -EFAULT; |
| 1405 | |
| 1406 | return ret; |
| 1407 | } |
| 1408 | |
| 1409 | if (opipe) { |
| 1410 | if (off_out) |
| 1411 | return -ESPIPE; |
| 1412 | if (off_in) { |
| 1413 | if (!(in->f_mode & FMODE_PREAD)) |
| 1414 | return -EINVAL; |
| 1415 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
| 1416 | return -EFAULT; |
| 1417 | } else { |
| 1418 | offset = in->f_pos; |
| 1419 | } |
| 1420 | |
| 1421 | ret = do_splice_to(in, &offset, opipe, len, flags); |
| 1422 | |
| 1423 | if (!off_in) |
| 1424 | in->f_pos = offset; |
| 1425 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) |
| 1426 | ret = -EFAULT; |
| 1427 | |
| 1428 | return ret; |
| 1429 | } |
| 1430 | |
| 1431 | return -EINVAL; |
| 1432 | } |
| 1433 | |
| 1434 | /* |
| 1435 | * Map an iov into an array of pages and offset/length tupples. With the |
| 1436 | * partial_page structure, we can map several non-contiguous ranges into |
| 1437 | * our ones pages[] map instead of splitting that operation into pieces. |
| 1438 | * Could easily be exported as a generic helper for other users, in which |
| 1439 | * case one would probably want to add a 'max_nr_pages' parameter as well. |
| 1440 | */ |
| 1441 | static int get_iovec_page_array(const struct iovec __user *iov, |
| 1442 | unsigned int nr_vecs, struct page **pages, |
| 1443 | struct partial_page *partial, bool aligned, |
| 1444 | unsigned int pipe_buffers) |
| 1445 | { |
| 1446 | int buffers = 0, error = 0; |
| 1447 | |
| 1448 | while (nr_vecs) { |
| 1449 | unsigned long off, npages; |
| 1450 | struct iovec entry; |
| 1451 | void __user *base; |
| 1452 | size_t len; |
| 1453 | int i; |
| 1454 | |
| 1455 | error = -EFAULT; |
| 1456 | if (copy_from_user(&entry, iov, sizeof(entry))) |
| 1457 | break; |
| 1458 | |
| 1459 | base = entry.iov_base; |
| 1460 | len = entry.iov_len; |
| 1461 | |
| 1462 | /* |
| 1463 | * Sanity check this iovec. 0 read succeeds. |
| 1464 | */ |
| 1465 | error = 0; |
| 1466 | if (unlikely(!len)) |
| 1467 | break; |
| 1468 | error = -EFAULT; |
| 1469 | if (!access_ok(VERIFY_READ, base, len)) |
| 1470 | break; |
| 1471 | |
| 1472 | /* |
| 1473 | * Get this base offset and number of pages, then map |
| 1474 | * in the user pages. |
| 1475 | */ |
| 1476 | off = (unsigned long) base & ~PAGE_MASK; |
| 1477 | |
| 1478 | /* |
| 1479 | * If asked for alignment, the offset must be zero and the |
| 1480 | * length a multiple of the PAGE_SIZE. |
| 1481 | */ |
| 1482 | error = -EINVAL; |
| 1483 | if (aligned && (off || len & ~PAGE_MASK)) |
| 1484 | break; |
| 1485 | |
| 1486 | npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| 1487 | if (npages > pipe_buffers - buffers) |
| 1488 | npages = pipe_buffers - buffers; |
| 1489 | |
| 1490 | error = get_user_pages_fast((unsigned long)base, npages, |
| 1491 | 0, &pages[buffers]); |
| 1492 | |
| 1493 | if (unlikely(error <= 0)) |
| 1494 | break; |
| 1495 | |
| 1496 | /* |
| 1497 | * Fill this contiguous range into the partial page map. |
| 1498 | */ |
| 1499 | for (i = 0; i < error; i++) { |
| 1500 | const int plen = min_t(size_t, len, PAGE_SIZE - off); |
| 1501 | |
| 1502 | partial[buffers].offset = off; |
| 1503 | partial[buffers].len = plen; |
| 1504 | |
| 1505 | off = 0; |
| 1506 | len -= plen; |
| 1507 | buffers++; |
| 1508 | } |
| 1509 | |
| 1510 | /* |
| 1511 | * We didn't complete this iov, stop here since it probably |
| 1512 | * means we have to move some of this into a pipe to |
| 1513 | * be able to continue. |
| 1514 | */ |
| 1515 | if (len) |
| 1516 | break; |
| 1517 | |
| 1518 | /* |
| 1519 | * Don't continue if we mapped fewer pages than we asked for, |
| 1520 | * or if we mapped the max number of pages that we have |
| 1521 | * room for. |
| 1522 | */ |
| 1523 | if (error < npages || buffers == pipe_buffers) |
| 1524 | break; |
| 1525 | |
| 1526 | nr_vecs--; |
| 1527 | iov++; |
| 1528 | } |
| 1529 | |
| 1530 | if (buffers) |
| 1531 | return buffers; |
| 1532 | |
| 1533 | return error; |
| 1534 | } |
| 1535 | |
| 1536 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
| 1537 | struct splice_desc *sd) |
| 1538 | { |
| 1539 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
| 1540 | return n == sd->len ? n : -EFAULT; |
| 1541 | } |
| 1542 | |
| 1543 | /* |
| 1544 | * For lack of a better implementation, implement vmsplice() to userspace |
| 1545 | * as a simple copy of the pipes pages to the user iov. |
| 1546 | */ |
| 1547 | static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov, |
| 1548 | unsigned long nr_segs, unsigned int flags) |
| 1549 | { |
| 1550 | struct pipe_inode_info *pipe; |
| 1551 | struct splice_desc sd; |
| 1552 | long ret; |
| 1553 | struct iovec iovstack[UIO_FASTIOV]; |
| 1554 | struct iovec *iov = iovstack; |
| 1555 | struct iov_iter iter; |
| 1556 | |
| 1557 | pipe = get_pipe_info(file); |
| 1558 | if (!pipe) |
| 1559 | return -EBADF; |
| 1560 | |
| 1561 | ret = import_iovec(READ, uiov, nr_segs, |
| 1562 | ARRAY_SIZE(iovstack), &iov, &iter); |
| 1563 | if (ret < 0) |
| 1564 | return ret; |
| 1565 | |
| 1566 | sd.total_len = iov_iter_count(&iter); |
| 1567 | sd.len = 0; |
| 1568 | sd.flags = flags; |
| 1569 | sd.u.data = &iter; |
| 1570 | sd.pos = 0; |
| 1571 | |
| 1572 | if (sd.total_len) { |
| 1573 | pipe_lock(pipe); |
| 1574 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); |
| 1575 | pipe_unlock(pipe); |
| 1576 | } |
| 1577 | |
| 1578 | kfree(iov); |
| 1579 | return ret; |
| 1580 | } |
| 1581 | |
| 1582 | /* |
| 1583 | * vmsplice splices a user address range into a pipe. It can be thought of |
| 1584 | * as splice-from-memory, where the regular splice is splice-from-file (or |
| 1585 | * to file). In both cases the output is a pipe, naturally. |
| 1586 | */ |
| 1587 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
| 1588 | unsigned long nr_segs, unsigned int flags) |
| 1589 | { |
| 1590 | struct pipe_inode_info *pipe; |
| 1591 | struct page *pages[PIPE_DEF_BUFFERS]; |
| 1592 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
| 1593 | struct splice_pipe_desc spd = { |
| 1594 | .pages = pages, |
| 1595 | .partial = partial, |
| 1596 | .nr_pages_max = PIPE_DEF_BUFFERS, |
| 1597 | .flags = flags, |
| 1598 | .ops = &user_page_pipe_buf_ops, |
| 1599 | .spd_release = spd_release_page, |
| 1600 | }; |
| 1601 | long ret; |
| 1602 | |
| 1603 | pipe = get_pipe_info(file); |
| 1604 | if (!pipe) |
| 1605 | return -EBADF; |
| 1606 | |
| 1607 | if (splice_grow_spd(pipe, &spd)) |
| 1608 | return -ENOMEM; |
| 1609 | |
| 1610 | spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, |
| 1611 | spd.partial, false, |
| 1612 | spd.nr_pages_max); |
| 1613 | if (spd.nr_pages <= 0) |
| 1614 | ret = spd.nr_pages; |
| 1615 | else |
| 1616 | ret = splice_to_pipe(pipe, &spd); |
| 1617 | |
| 1618 | splice_shrink_spd(&spd); |
| 1619 | return ret; |
| 1620 | } |
| 1621 | |
| 1622 | /* |
| 1623 | * Note that vmsplice only really supports true splicing _from_ user memory |
| 1624 | * to a pipe, not the other way around. Splicing from user memory is a simple |
| 1625 | * operation that can be supported without any funky alignment restrictions |
| 1626 | * or nasty vm tricks. We simply map in the user memory and fill them into |
| 1627 | * a pipe. The reverse isn't quite as easy, though. There are two possible |
| 1628 | * solutions for that: |
| 1629 | * |
| 1630 | * - memcpy() the data internally, at which point we might as well just |
| 1631 | * do a regular read() on the buffer anyway. |
| 1632 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it |
| 1633 | * has restriction limitations on both ends of the pipe). |
| 1634 | * |
| 1635 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). |
| 1636 | * |
| 1637 | */ |
| 1638 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
| 1639 | unsigned long, nr_segs, unsigned int, flags) |
| 1640 | { |
| 1641 | struct fd f; |
| 1642 | long error; |
| 1643 | |
| 1644 | if (unlikely(nr_segs > UIO_MAXIOV)) |
| 1645 | return -EINVAL; |
| 1646 | else if (unlikely(!nr_segs)) |
| 1647 | return 0; |
| 1648 | |
| 1649 | error = -EBADF; |
| 1650 | f = fdget(fd); |
| 1651 | if (f.file) { |
| 1652 | if (f.file->f_mode & FMODE_WRITE) |
| 1653 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); |
| 1654 | else if (f.file->f_mode & FMODE_READ) |
| 1655 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); |
| 1656 | |
| 1657 | fdput(f); |
| 1658 | } |
| 1659 | |
| 1660 | return error; |
| 1661 | } |
| 1662 | |
| 1663 | #ifdef CONFIG_COMPAT |
| 1664 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, |
| 1665 | unsigned int, nr_segs, unsigned int, flags) |
| 1666 | { |
| 1667 | unsigned i; |
| 1668 | struct iovec __user *iov; |
| 1669 | if (nr_segs > UIO_MAXIOV) |
| 1670 | return -EINVAL; |
| 1671 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); |
| 1672 | for (i = 0; i < nr_segs; i++) { |
| 1673 | struct compat_iovec v; |
| 1674 | if (get_user(v.iov_base, &iov32[i].iov_base) || |
| 1675 | get_user(v.iov_len, &iov32[i].iov_len) || |
| 1676 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || |
| 1677 | put_user(v.iov_len, &iov[i].iov_len)) |
| 1678 | return -EFAULT; |
| 1679 | } |
| 1680 | return sys_vmsplice(fd, iov, nr_segs, flags); |
| 1681 | } |
| 1682 | #endif |
| 1683 | |
| 1684 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
| 1685 | int, fd_out, loff_t __user *, off_out, |
| 1686 | size_t, len, unsigned int, flags) |
| 1687 | { |
| 1688 | struct fd in, out; |
| 1689 | long error; |
| 1690 | |
| 1691 | if (unlikely(!len)) |
| 1692 | return 0; |
| 1693 | |
| 1694 | error = -EBADF; |
| 1695 | in = fdget(fd_in); |
| 1696 | if (in.file) { |
| 1697 | if (in.file->f_mode & FMODE_READ) { |
| 1698 | out = fdget(fd_out); |
| 1699 | if (out.file) { |
| 1700 | if (out.file->f_mode & FMODE_WRITE) |
| 1701 | error = do_splice(in.file, off_in, |
| 1702 | out.file, off_out, |
| 1703 | len, flags); |
| 1704 | fdput(out); |
| 1705 | } |
| 1706 | } |
| 1707 | fdput(in); |
| 1708 | } |
| 1709 | return error; |
| 1710 | } |
| 1711 | |
| 1712 | /* |
| 1713 | * Make sure there's data to read. Wait for input if we can, otherwise |
| 1714 | * return an appropriate error. |
| 1715 | */ |
| 1716 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
| 1717 | { |
| 1718 | int ret; |
| 1719 | |
| 1720 | /* |
| 1721 | * Check ->nrbufs without the inode lock first. This function |
| 1722 | * is speculative anyways, so missing one is ok. |
| 1723 | */ |
| 1724 | if (pipe->nrbufs) |
| 1725 | return 0; |
| 1726 | |
| 1727 | ret = 0; |
| 1728 | pipe_lock(pipe); |
| 1729 | |
| 1730 | while (!pipe->nrbufs) { |
| 1731 | if (signal_pending(current)) { |
| 1732 | ret = -ERESTARTSYS; |
| 1733 | break; |
| 1734 | } |
| 1735 | if (!pipe->writers) |
| 1736 | break; |
| 1737 | if (!pipe->waiting_writers) { |
| 1738 | if (flags & SPLICE_F_NONBLOCK) { |
| 1739 | ret = -EAGAIN; |
| 1740 | break; |
| 1741 | } |
| 1742 | } |
| 1743 | pipe_wait(pipe); |
| 1744 | } |
| 1745 | |
| 1746 | pipe_unlock(pipe); |
| 1747 | return ret; |
| 1748 | } |
| 1749 | |
| 1750 | /* |
| 1751 | * Make sure there's writeable room. Wait for room if we can, otherwise |
| 1752 | * return an appropriate error. |
| 1753 | */ |
| 1754 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
| 1755 | { |
| 1756 | int ret; |
| 1757 | |
| 1758 | /* |
| 1759 | * Check ->nrbufs without the inode lock first. This function |
| 1760 | * is speculative anyways, so missing one is ok. |
| 1761 | */ |
| 1762 | if (pipe->nrbufs < pipe->buffers) |
| 1763 | return 0; |
| 1764 | |
| 1765 | ret = 0; |
| 1766 | pipe_lock(pipe); |
| 1767 | |
| 1768 | while (pipe->nrbufs >= pipe->buffers) { |
| 1769 | if (!pipe->readers) { |
| 1770 | send_sig(SIGPIPE, current, 0); |
| 1771 | ret = -EPIPE; |
| 1772 | break; |
| 1773 | } |
| 1774 | if (flags & SPLICE_F_NONBLOCK) { |
| 1775 | ret = -EAGAIN; |
| 1776 | break; |
| 1777 | } |
| 1778 | if (signal_pending(current)) { |
| 1779 | ret = -ERESTARTSYS; |
| 1780 | break; |
| 1781 | } |
| 1782 | pipe->waiting_writers++; |
| 1783 | pipe_wait(pipe); |
| 1784 | pipe->waiting_writers--; |
| 1785 | } |
| 1786 | |
| 1787 | pipe_unlock(pipe); |
| 1788 | return ret; |
| 1789 | } |
| 1790 | |
| 1791 | /* |
| 1792 | * Splice contents of ipipe to opipe. |
| 1793 | */ |
| 1794 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
| 1795 | struct pipe_inode_info *opipe, |
| 1796 | size_t len, unsigned int flags) |
| 1797 | { |
| 1798 | struct pipe_buffer *ibuf, *obuf; |
| 1799 | int ret = 0, nbuf; |
| 1800 | bool input_wakeup = false; |
| 1801 | |
| 1802 | |
| 1803 | retry: |
| 1804 | ret = ipipe_prep(ipipe, flags); |
| 1805 | if (ret) |
| 1806 | return ret; |
| 1807 | |
| 1808 | ret = opipe_prep(opipe, flags); |
| 1809 | if (ret) |
| 1810 | return ret; |
| 1811 | |
| 1812 | /* |
| 1813 | * Potential ABBA deadlock, work around it by ordering lock |
| 1814 | * grabbing by pipe info address. Otherwise two different processes |
| 1815 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
| 1816 | */ |
| 1817 | pipe_double_lock(ipipe, opipe); |
| 1818 | |
| 1819 | do { |
| 1820 | if (!opipe->readers) { |
| 1821 | send_sig(SIGPIPE, current, 0); |
| 1822 | if (!ret) |
| 1823 | ret = -EPIPE; |
| 1824 | break; |
| 1825 | } |
| 1826 | |
| 1827 | if (!ipipe->nrbufs && !ipipe->writers) |
| 1828 | break; |
| 1829 | |
| 1830 | /* |
| 1831 | * Cannot make any progress, because either the input |
| 1832 | * pipe is empty or the output pipe is full. |
| 1833 | */ |
| 1834 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
| 1835 | /* Already processed some buffers, break */ |
| 1836 | if (ret) |
| 1837 | break; |
| 1838 | |
| 1839 | if (flags & SPLICE_F_NONBLOCK) { |
| 1840 | ret = -EAGAIN; |
| 1841 | break; |
| 1842 | } |
| 1843 | |
| 1844 | /* |
| 1845 | * We raced with another reader/writer and haven't |
| 1846 | * managed to process any buffers. A zero return |
| 1847 | * value means EOF, so retry instead. |
| 1848 | */ |
| 1849 | pipe_unlock(ipipe); |
| 1850 | pipe_unlock(opipe); |
| 1851 | goto retry; |
| 1852 | } |
| 1853 | |
| 1854 | ibuf = ipipe->bufs + ipipe->curbuf; |
| 1855 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
| 1856 | obuf = opipe->bufs + nbuf; |
| 1857 | |
| 1858 | if (len >= ibuf->len) { |
| 1859 | /* |
| 1860 | * Simply move the whole buffer from ipipe to opipe |
| 1861 | */ |
| 1862 | *obuf = *ibuf; |
| 1863 | ibuf->ops = NULL; |
| 1864 | opipe->nrbufs++; |
| 1865 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
| 1866 | ipipe->nrbufs--; |
| 1867 | input_wakeup = true; |
| 1868 | } else { |
| 1869 | /* |
| 1870 | * Get a reference to this pipe buffer, |
| 1871 | * so we can copy the contents over. |
| 1872 | */ |
| 1873 | ibuf->ops->get(ipipe, ibuf); |
| 1874 | *obuf = *ibuf; |
| 1875 | |
| 1876 | /* |
| 1877 | * Don't inherit the gift flag, we need to |
| 1878 | * prevent multiple steals of this page. |
| 1879 | */ |
| 1880 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
| 1881 | |
| 1882 | obuf->len = len; |
| 1883 | opipe->nrbufs++; |
| 1884 | ibuf->offset += obuf->len; |
| 1885 | ibuf->len -= obuf->len; |
| 1886 | } |
| 1887 | ret += obuf->len; |
| 1888 | len -= obuf->len; |
| 1889 | } while (len); |
| 1890 | |
| 1891 | pipe_unlock(ipipe); |
| 1892 | pipe_unlock(opipe); |
| 1893 | |
| 1894 | /* |
| 1895 | * If we put data in the output pipe, wakeup any potential readers. |
| 1896 | */ |
| 1897 | if (ret > 0) |
| 1898 | wakeup_pipe_readers(opipe); |
| 1899 | |
| 1900 | if (input_wakeup) |
| 1901 | wakeup_pipe_writers(ipipe); |
| 1902 | |
| 1903 | return ret; |
| 1904 | } |
| 1905 | |
| 1906 | /* |
| 1907 | * Link contents of ipipe to opipe. |
| 1908 | */ |
| 1909 | static int link_pipe(struct pipe_inode_info *ipipe, |
| 1910 | struct pipe_inode_info *opipe, |
| 1911 | size_t len, unsigned int flags) |
| 1912 | { |
| 1913 | struct pipe_buffer *ibuf, *obuf; |
| 1914 | int ret = 0, i = 0, nbuf; |
| 1915 | |
| 1916 | /* |
| 1917 | * Potential ABBA deadlock, work around it by ordering lock |
| 1918 | * grabbing by pipe info address. Otherwise two different processes |
| 1919 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
| 1920 | */ |
| 1921 | pipe_double_lock(ipipe, opipe); |
| 1922 | |
| 1923 | do { |
| 1924 | if (!opipe->readers) { |
| 1925 | send_sig(SIGPIPE, current, 0); |
| 1926 | if (!ret) |
| 1927 | ret = -EPIPE; |
| 1928 | break; |
| 1929 | } |
| 1930 | |
| 1931 | /* |
| 1932 | * If we have iterated all input buffers or ran out of |
| 1933 | * output room, break. |
| 1934 | */ |
| 1935 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
| 1936 | break; |
| 1937 | |
| 1938 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
| 1939 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
| 1940 | |
| 1941 | /* |
| 1942 | * Get a reference to this pipe buffer, |
| 1943 | * so we can copy the contents over. |
| 1944 | */ |
| 1945 | ibuf->ops->get(ipipe, ibuf); |
| 1946 | |
| 1947 | obuf = opipe->bufs + nbuf; |
| 1948 | *obuf = *ibuf; |
| 1949 | |
| 1950 | /* |
| 1951 | * Don't inherit the gift flag, we need to |
| 1952 | * prevent multiple steals of this page. |
| 1953 | */ |
| 1954 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
| 1955 | |
| 1956 | if (obuf->len > len) |
| 1957 | obuf->len = len; |
| 1958 | |
| 1959 | opipe->nrbufs++; |
| 1960 | ret += obuf->len; |
| 1961 | len -= obuf->len; |
| 1962 | i++; |
| 1963 | } while (len); |
| 1964 | |
| 1965 | /* |
| 1966 | * return EAGAIN if we have the potential of some data in the |
| 1967 | * future, otherwise just return 0 |
| 1968 | */ |
| 1969 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) |
| 1970 | ret = -EAGAIN; |
| 1971 | |
| 1972 | pipe_unlock(ipipe); |
| 1973 | pipe_unlock(opipe); |
| 1974 | |
| 1975 | /* |
| 1976 | * If we put data in the output pipe, wakeup any potential readers. |
| 1977 | */ |
| 1978 | if (ret > 0) |
| 1979 | wakeup_pipe_readers(opipe); |
| 1980 | |
| 1981 | return ret; |
| 1982 | } |
| 1983 | |
| 1984 | /* |
| 1985 | * This is a tee(1) implementation that works on pipes. It doesn't copy |
| 1986 | * any data, it simply references the 'in' pages on the 'out' pipe. |
| 1987 | * The 'flags' used are the SPLICE_F_* variants, currently the only |
| 1988 | * applicable one is SPLICE_F_NONBLOCK. |
| 1989 | */ |
| 1990 | static long do_tee(struct file *in, struct file *out, size_t len, |
| 1991 | unsigned int flags) |
| 1992 | { |
| 1993 | struct pipe_inode_info *ipipe = get_pipe_info(in); |
| 1994 | struct pipe_inode_info *opipe = get_pipe_info(out); |
| 1995 | int ret = -EINVAL; |
| 1996 | |
| 1997 | /* |
| 1998 | * Duplicate the contents of ipipe to opipe without actually |
| 1999 | * copying the data. |
| 2000 | */ |
| 2001 | if (ipipe && opipe && ipipe != opipe) { |
| 2002 | /* |
| 2003 | * Keep going, unless we encounter an error. The ipipe/opipe |
| 2004 | * ordering doesn't really matter. |
| 2005 | */ |
| 2006 | ret = ipipe_prep(ipipe, flags); |
| 2007 | if (!ret) { |
| 2008 | ret = opipe_prep(opipe, flags); |
| 2009 | if (!ret) |
| 2010 | ret = link_pipe(ipipe, opipe, len, flags); |
| 2011 | } |
| 2012 | } |
| 2013 | |
| 2014 | return ret; |
| 2015 | } |
| 2016 | |
| 2017 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
| 2018 | { |
| 2019 | struct fd in; |
| 2020 | int error; |
| 2021 | |
| 2022 | if (unlikely(!len)) |
| 2023 | return 0; |
| 2024 | |
| 2025 | error = -EBADF; |
| 2026 | in = fdget(fdin); |
| 2027 | if (in.file) { |
| 2028 | if (in.file->f_mode & FMODE_READ) { |
| 2029 | struct fd out = fdget(fdout); |
| 2030 | if (out.file) { |
| 2031 | if (out.file->f_mode & FMODE_WRITE) |
| 2032 | error = do_tee(in.file, out.file, |
| 2033 | len, flags); |
| 2034 | fdput(out); |
| 2035 | } |
| 2036 | } |
| 2037 | fdput(in); |
| 2038 | } |
| 2039 | |
| 2040 | return error; |
| 2041 | } |