Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
5274f052 JA |
2 | /* |
3 | * "splice": joining two ropes together by interweaving their strands. | |
4 | * | |
5 | * This is the "extended pipe" functionality, where a pipe is used as | |
6 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel | |
7 | * buffer that you can use to transfer data from one end to the other. | |
8 | * | |
9 | * The traditional unix read/write is extended with a "splice()" operation | |
10 | * that transfers data buffers to or from a pipe buffer. | |
11 | * | |
12 | * Named by Larry McVoy, original implementation from Linus, extended by | |
c2058e06 JA |
13 | * Jens to support splicing to files, network, direct splicing, etc and |
14 | * fixing lots of bugs. | |
5274f052 | 15 | * |
0fe23479 | 16 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
c2058e06 JA |
17 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
18 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> | |
5274f052 JA |
19 | * |
20 | */ | |
be297968 | 21 | #include <linux/bvec.h> |
5274f052 JA |
22 | #include <linux/fs.h> |
23 | #include <linux/file.h> | |
24 | #include <linux/pagemap.h> | |
d6b29d7c | 25 | #include <linux/splice.h> |
08e552c6 | 26 | #include <linux/memcontrol.h> |
5274f052 | 27 | #include <linux/mm_inline.h> |
5abc97aa | 28 | #include <linux/swap.h> |
4f6f0bd2 | 29 | #include <linux/writeback.h> |
630d9c47 | 30 | #include <linux/export.h> |
4f6f0bd2 | 31 | #include <linux/syscalls.h> |
912d35f8 | 32 | #include <linux/uio.h> |
29ce2058 | 33 | #include <linux/security.h> |
5a0e3ad6 | 34 | #include <linux/gfp.h> |
35f9c09f | 35 | #include <linux/socket.h> |
174cd4b1 IM |
36 | #include <linux/sched/signal.h> |
37 | ||
06ae43f3 | 38 | #include "internal.h" |
5274f052 | 39 | |
83f9135b JA |
40 | /* |
41 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
42 | * a vm helper function, it's already simplified quite a bit by the | |
43 | * addition of remove_mapping(). If success is returned, the caller may | |
44 | * attempt to reuse this page for another destination. | |
45 | */ | |
c928f642 CH |
46 | static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
47 | struct pipe_buffer *buf) | |
5abc97aa | 48 | { |
5100da38 | 49 | struct folio *folio = page_folio(buf->page); |
9e94cd4f | 50 | struct address_space *mapping; |
5abc97aa | 51 | |
b9ccad2e | 52 | folio_lock(folio); |
9e0267c2 | 53 | |
b9ccad2e | 54 | mapping = folio_mapping(folio); |
9e94cd4f | 55 | if (mapping) { |
b9ccad2e | 56 | WARN_ON(!folio_test_uptodate(folio)); |
5abc97aa | 57 | |
9e94cd4f JA |
58 | /* |
59 | * At least for ext2 with nobh option, we need to wait on | |
b9ccad2e | 60 | * writeback completing on this folio, since we'll remove it |
9e94cd4f | 61 | * from the pagecache. Otherwise truncate wont wait on the |
b9ccad2e | 62 | * folio, allowing the disk blocks to be reused by someone else |
9e94cd4f JA |
63 | * before we actually wrote our data to them. fs corruption |
64 | * ensues. | |
65 | */ | |
b9ccad2e | 66 | folio_wait_writeback(folio); |
ad8d6f0a | 67 | |
b9ccad2e MWO |
68 | if (folio_has_private(folio) && |
69 | !filemap_release_folio(folio, GFP_KERNEL)) | |
ca39d651 | 70 | goto out_unlock; |
4f6f0bd2 | 71 | |
9e94cd4f JA |
72 | /* |
73 | * If we succeeded in removing the mapping, set LRU flag | |
74 | * and return good. | |
75 | */ | |
5100da38 | 76 | if (remove_mapping(mapping, folio)) { |
9e94cd4f | 77 | buf->flags |= PIPE_BUF_FLAG_LRU; |
c928f642 | 78 | return true; |
9e94cd4f | 79 | } |
9e0267c2 | 80 | } |
5abc97aa | 81 | |
9e94cd4f | 82 | /* |
b9ccad2e | 83 | * Raced with truncate or failed to remove folio from current |
9e94cd4f JA |
84 | * address space, unlock and return failure. |
85 | */ | |
ca39d651 | 86 | out_unlock: |
b9ccad2e | 87 | folio_unlock(folio); |
c928f642 | 88 | return false; |
5abc97aa JA |
89 | } |
90 | ||
76ad4d11 | 91 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
5274f052 JA |
92 | struct pipe_buffer *buf) |
93 | { | |
09cbfeaf | 94 | put_page(buf->page); |
1432873a | 95 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
96 | } |
97 | ||
0845718d JA |
98 | /* |
99 | * Check whether the contents of buf is OK to access. Since the content | |
100 | * is a page cache page, IO may be in flight. | |
101 | */ | |
cac36bb0 JA |
102 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
103 | struct pipe_buffer *buf) | |
5274f052 JA |
104 | { |
105 | struct page *page = buf->page; | |
49d0b21b | 106 | int err; |
5274f052 JA |
107 | |
108 | if (!PageUptodate(page)) { | |
49d0b21b JA |
109 | lock_page(page); |
110 | ||
111 | /* | |
112 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 113 | * splice, if this is the first page. |
49d0b21b JA |
114 | */ |
115 | if (!page->mapping) { | |
116 | err = -ENODATA; | |
117 | goto error; | |
118 | } | |
5274f052 | 119 | |
49d0b21b | 120 | /* |
73d62d83 | 121 | * Uh oh, read-error from disk. |
49d0b21b JA |
122 | */ |
123 | if (!PageUptodate(page)) { | |
124 | err = -EIO; | |
125 | goto error; | |
126 | } | |
127 | ||
128 | /* | |
f84d7519 | 129 | * Page is ok afterall, we are done. |
49d0b21b | 130 | */ |
5274f052 | 131 | unlock_page(page); |
5274f052 JA |
132 | } |
133 | ||
f84d7519 | 134 | return 0; |
49d0b21b JA |
135 | error: |
136 | unlock_page(page); | |
f84d7519 | 137 | return err; |
70524490 JA |
138 | } |
139 | ||
708e3508 | 140 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
c928f642 CH |
141 | .confirm = page_cache_pipe_buf_confirm, |
142 | .release = page_cache_pipe_buf_release, | |
143 | .try_steal = page_cache_pipe_buf_try_steal, | |
144 | .get = generic_pipe_buf_get, | |
5274f052 JA |
145 | }; |
146 | ||
c928f642 CH |
147 | static bool user_page_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
148 | struct pipe_buffer *buf) | |
912d35f8 | 149 | { |
7afa6fd0 | 150 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
c928f642 | 151 | return false; |
7afa6fd0 | 152 | |
1432873a | 153 | buf->flags |= PIPE_BUF_FLAG_LRU; |
c928f642 | 154 | return generic_pipe_buf_try_steal(pipe, buf); |
912d35f8 JA |
155 | } |
156 | ||
d4c3cca9 | 157 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
c928f642 CH |
158 | .release = page_cache_pipe_buf_release, |
159 | .try_steal = user_page_pipe_buf_try_steal, | |
160 | .get = generic_pipe_buf_get, | |
912d35f8 JA |
161 | }; |
162 | ||
825cdcb1 NK |
163 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
164 | { | |
165 | smp_mb(); | |
0ddad21d LT |
166 | if (waitqueue_active(&pipe->rd_wait)) |
167 | wake_up_interruptible(&pipe->rd_wait); | |
825cdcb1 NK |
168 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
169 | } | |
170 | ||
932cc6d4 JA |
171 | /** |
172 | * splice_to_pipe - fill passed data into a pipe | |
173 | * @pipe: pipe to fill | |
174 | * @spd: data to fill | |
175 | * | |
176 | * Description: | |
79685b8d | 177 | * @spd contains a map of pages and len/offset tuples, along with |
932cc6d4 JA |
178 | * the struct pipe_buf_operations associated with these pages. This |
179 | * function will link that data to the pipe. | |
180 | * | |
83f9135b | 181 | */ |
d6b29d7c JA |
182 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
183 | struct splice_pipe_desc *spd) | |
5274f052 | 184 | { |
00de00bd | 185 | unsigned int spd_pages = spd->nr_pages; |
8cefc107 DH |
186 | unsigned int tail = pipe->tail; |
187 | unsigned int head = pipe->head; | |
188 | unsigned int mask = pipe->ring_size - 1; | |
8924feff | 189 | int ret = 0, page_nr = 0; |
5274f052 | 190 | |
d6785d91 RV |
191 | if (!spd_pages) |
192 | return 0; | |
193 | ||
8924feff AV |
194 | if (unlikely(!pipe->readers)) { |
195 | send_sig(SIGPIPE, current, 0); | |
196 | ret = -EPIPE; | |
197 | goto out; | |
198 | } | |
5274f052 | 199 | |
6718b6f8 | 200 | while (!pipe_full(head, tail, pipe->max_usage)) { |
8cefc107 | 201 | struct pipe_buffer *buf = &pipe->bufs[head & mask]; |
5274f052 | 202 | |
8924feff AV |
203 | buf->page = spd->pages[page_nr]; |
204 | buf->offset = spd->partial[page_nr].offset; | |
205 | buf->len = spd->partial[page_nr].len; | |
206 | buf->private = spd->partial[page_nr].private; | |
207 | buf->ops = spd->ops; | |
5a81e6a1 | 208 | buf->flags = 0; |
5274f052 | 209 | |
8cefc107 DH |
210 | head++; |
211 | pipe->head = head; | |
8924feff AV |
212 | page_nr++; |
213 | ret += buf->len; | |
29e35094 | 214 | |
8924feff | 215 | if (!--spd->nr_pages) |
5274f052 | 216 | break; |
5274f052 JA |
217 | } |
218 | ||
8924feff AV |
219 | if (!ret) |
220 | ret = -EAGAIN; | |
5274f052 | 221 | |
8924feff | 222 | out: |
00de00bd | 223 | while (page_nr < spd_pages) |
bbdfc2f7 | 224 | spd->spd_release(spd, page_nr++); |
5274f052 JA |
225 | |
226 | return ret; | |
227 | } | |
2b514574 | 228 | EXPORT_SYMBOL_GPL(splice_to_pipe); |
5274f052 | 229 | |
79fddc4e AV |
230 | ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
231 | { | |
8cefc107 DH |
232 | unsigned int head = pipe->head; |
233 | unsigned int tail = pipe->tail; | |
234 | unsigned int mask = pipe->ring_size - 1; | |
79fddc4e AV |
235 | int ret; |
236 | ||
237 | if (unlikely(!pipe->readers)) { | |
238 | send_sig(SIGPIPE, current, 0); | |
239 | ret = -EPIPE; | |
6718b6f8 | 240 | } else if (pipe_full(head, tail, pipe->max_usage)) { |
79fddc4e AV |
241 | ret = -EAGAIN; |
242 | } else { | |
8cefc107 DH |
243 | pipe->bufs[head & mask] = *buf; |
244 | pipe->head = head + 1; | |
79fddc4e AV |
245 | return buf->len; |
246 | } | |
a779638c | 247 | pipe_buf_release(pipe, buf); |
79fddc4e AV |
248 | return ret; |
249 | } | |
250 | EXPORT_SYMBOL(add_to_pipe); | |
251 | ||
35f3d14d JA |
252 | /* |
253 | * Check if we need to grow the arrays holding pages and partial page | |
254 | * descriptions. | |
255 | */ | |
047fe360 | 256 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
35f3d14d | 257 | { |
6718b6f8 | 258 | unsigned int max_usage = READ_ONCE(pipe->max_usage); |
047fe360 | 259 | |
8cefc107 DH |
260 | spd->nr_pages_max = max_usage; |
261 | if (max_usage <= PIPE_DEF_BUFFERS) | |
35f3d14d JA |
262 | return 0; |
263 | ||
8cefc107 DH |
264 | spd->pages = kmalloc_array(max_usage, sizeof(struct page *), GFP_KERNEL); |
265 | spd->partial = kmalloc_array(max_usage, sizeof(struct partial_page), | |
6da2ec56 | 266 | GFP_KERNEL); |
35f3d14d JA |
267 | |
268 | if (spd->pages && spd->partial) | |
269 | return 0; | |
270 | ||
271 | kfree(spd->pages); | |
272 | kfree(spd->partial); | |
273 | return -ENOMEM; | |
274 | } | |
275 | ||
047fe360 | 276 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
35f3d14d | 277 | { |
047fe360 | 278 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
35f3d14d JA |
279 | return; |
280 | ||
281 | kfree(spd->pages); | |
282 | kfree(spd->partial); | |
283 | } | |
284 | ||
83f9135b JA |
285 | /** |
286 | * generic_file_splice_read - splice data from file to a pipe | |
287 | * @in: file to splice from | |
932cc6d4 | 288 | * @ppos: position in @in |
83f9135b JA |
289 | * @pipe: pipe to splice to |
290 | * @len: number of bytes to splice | |
291 | * @flags: splice modifier flags | |
292 | * | |
932cc6d4 JA |
293 | * Description: |
294 | * Will read pages from given file and fill them into a pipe. Can be | |
82c156f8 | 295 | * used as long as it has more or less sane ->read_iter(). |
932cc6d4 | 296 | * |
83f9135b | 297 | */ |
cbb7e577 JA |
298 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
299 | struct pipe_inode_info *pipe, size_t len, | |
300 | unsigned int flags) | |
5274f052 | 301 | { |
82c156f8 AV |
302 | struct iov_iter to; |
303 | struct kiocb kiocb; | |
8cefc107 | 304 | int ret; |
be64f884 | 305 | |
de4eda9d | 306 | iov_iter_pipe(&to, ITER_DEST, pipe, len); |
82c156f8 AV |
307 | init_sync_kiocb(&kiocb, in); |
308 | kiocb.ki_pos = *ppos; | |
bb7462b6 | 309 | ret = call_read_iter(in, &kiocb, &to); |
723590ed | 310 | if (ret > 0) { |
82c156f8 | 311 | *ppos = kiocb.ki_pos; |
723590ed | 312 | file_accessed(in); |
82c156f8 | 313 | } else if (ret < 0) { |
0d964934 AV |
314 | /* free what was emitted */ |
315 | pipe_discard_from(pipe, to.start_head); | |
82c156f8 AV |
316 | /* |
317 | * callers of ->splice_read() expect -EAGAIN on | |
318 | * "can't put anything in there", rather than -EFAULT. | |
319 | */ | |
320 | if (ret == -EFAULT) | |
321 | ret = -EAGAIN; | |
723590ed | 322 | } |
5274f052 JA |
323 | |
324 | return ret; | |
325 | } | |
059a8f37 JA |
326 | EXPORT_SYMBOL(generic_file_splice_read); |
327 | ||
241699cd | 328 | const struct pipe_buf_operations default_pipe_buf_ops = { |
c928f642 CH |
329 | .release = generic_pipe_buf_release, |
330 | .try_steal = generic_pipe_buf_try_steal, | |
331 | .get = generic_pipe_buf_get, | |
6818173b MS |
332 | }; |
333 | ||
28a625cb MS |
334 | /* Pipe buffer operations for a socket and similar. */ |
335 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { | |
c928f642 CH |
336 | .release = generic_pipe_buf_release, |
337 | .get = generic_pipe_buf_get, | |
28a625cb MS |
338 | }; |
339 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); | |
340 | ||
5274f052 | 341 | /* |
4f6f0bd2 | 342 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 343 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 344 | */ |
76ad4d11 | 345 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
346 | struct pipe_buffer *buf, struct splice_desc *sd) |
347 | { | |
6a14b90b | 348 | struct file *file = sd->u.file; |
5274f052 | 349 | loff_t pos = sd->pos; |
a8adbe37 | 350 | int more; |
5274f052 | 351 | |
72c2d531 | 352 | if (!likely(file->f_op->sendpage)) |
a8adbe37 MM |
353 | return -EINVAL; |
354 | ||
35f9c09f | 355 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
ae62ca7b | 356 | |
8cefc107 DH |
357 | if (sd->len < sd->total_len && |
358 | pipe_occupancy(pipe->head, pipe->tail) > 1) | |
35f9c09f | 359 | more |= MSG_SENDPAGE_NOTLAST; |
ae62ca7b | 360 | |
a8adbe37 MM |
361 | return file->f_op->sendpage(file, buf->page, buf->offset, |
362 | sd->len, &pos, more); | |
5274f052 JA |
363 | } |
364 | ||
b3c2d2dd MS |
365 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
366 | { | |
367 | smp_mb(); | |
0ddad21d LT |
368 | if (waitqueue_active(&pipe->wr_wait)) |
369 | wake_up_interruptible(&pipe->wr_wait); | |
b3c2d2dd MS |
370 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
371 | } | |
372 | ||
932cc6d4 | 373 | /** |
b3c2d2dd | 374 | * splice_from_pipe_feed - feed available data from a pipe to a file |
932cc6d4 JA |
375 | * @pipe: pipe to splice from |
376 | * @sd: information to @actor | |
377 | * @actor: handler that splices the data | |
378 | * | |
379 | * Description: | |
b3c2d2dd MS |
380 | * This function loops over the pipe and calls @actor to do the |
381 | * actual moving of a single struct pipe_buffer to the desired | |
382 | * destination. It returns when there's no more buffers left in | |
383 | * the pipe or if the requested number of bytes (@sd->total_len) | |
384 | * have been copied. It returns a positive number (one) if the | |
385 | * pipe needs to be filled with more data, zero if the required | |
386 | * number of bytes have been copied and -errno on error. | |
932cc6d4 | 387 | * |
b3c2d2dd MS |
388 | * This, together with splice_from_pipe_{begin,end,next}, may be |
389 | * used to implement the functionality of __splice_from_pipe() when | |
390 | * locking is required around copying the pipe buffers to the | |
391 | * destination. | |
83f9135b | 392 | */ |
96f9bc8f | 393 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
b3c2d2dd | 394 | splice_actor *actor) |
5274f052 | 395 | { |
8cefc107 DH |
396 | unsigned int head = pipe->head; |
397 | unsigned int tail = pipe->tail; | |
398 | unsigned int mask = pipe->ring_size - 1; | |
b3c2d2dd | 399 | int ret; |
5274f052 | 400 | |
ec057595 | 401 | while (!pipe_empty(head, tail)) { |
8cefc107 | 402 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
5274f052 | 403 | |
b3c2d2dd MS |
404 | sd->len = buf->len; |
405 | if (sd->len > sd->total_len) | |
406 | sd->len = sd->total_len; | |
5274f052 | 407 | |
fba597db | 408 | ret = pipe_buf_confirm(pipe, buf); |
a8adbe37 | 409 | if (unlikely(ret)) { |
b3c2d2dd MS |
410 | if (ret == -ENODATA) |
411 | ret = 0; | |
412 | return ret; | |
413 | } | |
a8adbe37 MM |
414 | |
415 | ret = actor(pipe, buf, sd); | |
416 | if (ret <= 0) | |
417 | return ret; | |
418 | ||
b3c2d2dd MS |
419 | buf->offset += ret; |
420 | buf->len -= ret; | |
421 | ||
422 | sd->num_spliced += ret; | |
423 | sd->len -= ret; | |
424 | sd->pos += ret; | |
425 | sd->total_len -= ret; | |
426 | ||
427 | if (!buf->len) { | |
a779638c | 428 | pipe_buf_release(pipe, buf); |
8cefc107 DH |
429 | tail++; |
430 | pipe->tail = tail; | |
6447a3cf | 431 | if (pipe->files) |
b3c2d2dd MS |
432 | sd->need_wakeup = true; |
433 | } | |
5274f052 | 434 | |
b3c2d2dd MS |
435 | if (!sd->total_len) |
436 | return 0; | |
437 | } | |
5274f052 | 438 | |
b3c2d2dd MS |
439 | return 1; |
440 | } | |
5274f052 | 441 | |
d1a819a2 LT |
442 | /* We know we have a pipe buffer, but maybe it's empty? */ |
443 | static inline bool eat_empty_buffer(struct pipe_inode_info *pipe) | |
444 | { | |
445 | unsigned int tail = pipe->tail; | |
446 | unsigned int mask = pipe->ring_size - 1; | |
447 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; | |
448 | ||
449 | if (unlikely(!buf->len)) { | |
450 | pipe_buf_release(pipe, buf); | |
451 | pipe->tail = tail+1; | |
452 | return true; | |
453 | } | |
454 | ||
455 | return false; | |
456 | } | |
457 | ||
b3c2d2dd MS |
458 | /** |
459 | * splice_from_pipe_next - wait for some data to splice from | |
460 | * @pipe: pipe to splice from | |
461 | * @sd: information about the splice operation | |
462 | * | |
463 | * Description: | |
464 | * This function will wait for some data and return a positive | |
465 | * value (one) if pipe buffers are available. It will return zero | |
466 | * or -errno if no more data needs to be spliced. | |
467 | */ | |
96f9bc8f | 468 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd | 469 | { |
c725bfce JK |
470 | /* |
471 | * Check for signal early to make process killable when there are | |
472 | * always buffers available | |
473 | */ | |
474 | if (signal_pending(current)) | |
475 | return -ERESTARTSYS; | |
476 | ||
d1a819a2 | 477 | repeat: |
8cefc107 | 478 | while (pipe_empty(pipe->head, pipe->tail)) { |
b3c2d2dd MS |
479 | if (!pipe->writers) |
480 | return 0; | |
016b661e | 481 | |
a28c8b9d | 482 | if (sd->num_spliced) |
b3c2d2dd | 483 | return 0; |
73d62d83 | 484 | |
b3c2d2dd MS |
485 | if (sd->flags & SPLICE_F_NONBLOCK) |
486 | return -EAGAIN; | |
5274f052 | 487 | |
b3c2d2dd MS |
488 | if (signal_pending(current)) |
489 | return -ERESTARTSYS; | |
5274f052 | 490 | |
b3c2d2dd MS |
491 | if (sd->need_wakeup) { |
492 | wakeup_pipe_writers(pipe); | |
493 | sd->need_wakeup = false; | |
5274f052 JA |
494 | } |
495 | ||
472e5b05 | 496 | pipe_wait_readable(pipe); |
b3c2d2dd | 497 | } |
29e35094 | 498 | |
d1a819a2 LT |
499 | if (eat_empty_buffer(pipe)) |
500 | goto repeat; | |
501 | ||
b3c2d2dd MS |
502 | return 1; |
503 | } | |
5274f052 | 504 | |
b3c2d2dd MS |
505 | /** |
506 | * splice_from_pipe_begin - start splicing from pipe | |
b80901bb | 507 | * @sd: information about the splice operation |
b3c2d2dd MS |
508 | * |
509 | * Description: | |
510 | * This function should be called before a loop containing | |
511 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
512 | * initialize the necessary fields of @sd. | |
513 | */ | |
96f9bc8f | 514 | static void splice_from_pipe_begin(struct splice_desc *sd) |
b3c2d2dd MS |
515 | { |
516 | sd->num_spliced = 0; | |
517 | sd->need_wakeup = false; | |
518 | } | |
5274f052 | 519 | |
b3c2d2dd MS |
520 | /** |
521 | * splice_from_pipe_end - finish splicing from pipe | |
522 | * @pipe: pipe to splice from | |
523 | * @sd: information about the splice operation | |
524 | * | |
525 | * Description: | |
526 | * This function will wake up pipe writers if necessary. It should | |
527 | * be called after a loop containing splice_from_pipe_next() and | |
528 | * splice_from_pipe_feed(). | |
529 | */ | |
96f9bc8f | 530 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd MS |
531 | { |
532 | if (sd->need_wakeup) | |
533 | wakeup_pipe_writers(pipe); | |
534 | } | |
5274f052 | 535 | |
b3c2d2dd MS |
536 | /** |
537 | * __splice_from_pipe - splice data from a pipe to given actor | |
538 | * @pipe: pipe to splice from | |
539 | * @sd: information to @actor | |
540 | * @actor: handler that splices the data | |
541 | * | |
542 | * Description: | |
543 | * This function does little more than loop over the pipe and call | |
544 | * @actor to do the actual moving of a single struct pipe_buffer to | |
545 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
546 | * pipe_to_user. | |
547 | * | |
548 | */ | |
549 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
550 | splice_actor *actor) | |
551 | { | |
552 | int ret; | |
5274f052 | 553 | |
b3c2d2dd MS |
554 | splice_from_pipe_begin(sd); |
555 | do { | |
c2489e07 | 556 | cond_resched(); |
b3c2d2dd MS |
557 | ret = splice_from_pipe_next(pipe, sd); |
558 | if (ret > 0) | |
559 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
560 | } while (ret > 0); | |
561 | splice_from_pipe_end(pipe, sd); | |
562 | ||
563 | return sd->num_spliced ? sd->num_spliced : ret; | |
5274f052 | 564 | } |
40bee44e | 565 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 566 | |
932cc6d4 JA |
567 | /** |
568 | * splice_from_pipe - splice data from a pipe to a file | |
569 | * @pipe: pipe to splice from | |
570 | * @out: file to splice to | |
571 | * @ppos: position in @out | |
572 | * @len: how many bytes to splice | |
573 | * @flags: splice modifier flags | |
574 | * @actor: handler that splices the data | |
575 | * | |
576 | * Description: | |
2933970b | 577 | * See __splice_from_pipe. This function locks the pipe inode, |
932cc6d4 JA |
578 | * otherwise it's identical to __splice_from_pipe(). |
579 | * | |
580 | */ | |
6da61809 MF |
581 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
582 | loff_t *ppos, size_t len, unsigned int flags, | |
583 | splice_actor *actor) | |
584 | { | |
585 | ssize_t ret; | |
c66ab6fa JA |
586 | struct splice_desc sd = { |
587 | .total_len = len, | |
588 | .flags = flags, | |
589 | .pos = *ppos, | |
6a14b90b | 590 | .u.file = out, |
c66ab6fa | 591 | }; |
6da61809 | 592 | |
61e0d47c | 593 | pipe_lock(pipe); |
c66ab6fa | 594 | ret = __splice_from_pipe(pipe, &sd, actor); |
61e0d47c | 595 | pipe_unlock(pipe); |
6da61809 MF |
596 | |
597 | return ret; | |
598 | } | |
599 | ||
8d020765 AV |
600 | /** |
601 | * iter_file_splice_write - splice data from a pipe to a file | |
602 | * @pipe: pipe info | |
603 | * @out: file to write to | |
604 | * @ppos: position in @out | |
605 | * @len: number of bytes to splice | |
606 | * @flags: splice modifier flags | |
607 | * | |
608 | * Description: | |
609 | * Will either move or copy pages (determined by @flags options) from | |
610 | * the given pipe inode to the given file. | |
611 | * This one is ->write_iter-based. | |
612 | * | |
613 | */ | |
614 | ssize_t | |
615 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
616 | loff_t *ppos, size_t len, unsigned int flags) | |
617 | { | |
618 | struct splice_desc sd = { | |
619 | .total_len = len, | |
620 | .flags = flags, | |
621 | .pos = *ppos, | |
622 | .u.file = out, | |
623 | }; | |
6718b6f8 | 624 | int nbufs = pipe->max_usage; |
8d020765 AV |
625 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), |
626 | GFP_KERNEL); | |
627 | ssize_t ret; | |
628 | ||
629 | if (unlikely(!array)) | |
630 | return -ENOMEM; | |
631 | ||
632 | pipe_lock(pipe); | |
633 | ||
634 | splice_from_pipe_begin(&sd); | |
635 | while (sd.total_len) { | |
636 | struct iov_iter from; | |
ec057595 | 637 | unsigned int head, tail, mask; |
8d020765 | 638 | size_t left; |
8cefc107 | 639 | int n; |
8d020765 AV |
640 | |
641 | ret = splice_from_pipe_next(pipe, &sd); | |
642 | if (ret <= 0) | |
643 | break; | |
644 | ||
6718b6f8 | 645 | if (unlikely(nbufs < pipe->max_usage)) { |
8d020765 | 646 | kfree(array); |
6718b6f8 | 647 | nbufs = pipe->max_usage; |
8d020765 AV |
648 | array = kcalloc(nbufs, sizeof(struct bio_vec), |
649 | GFP_KERNEL); | |
650 | if (!array) { | |
651 | ret = -ENOMEM; | |
652 | break; | |
653 | } | |
654 | } | |
655 | ||
ec057595 LT |
656 | head = pipe->head; |
657 | tail = pipe->tail; | |
658 | mask = pipe->ring_size - 1; | |
659 | ||
8d020765 AV |
660 | /* build the vector */ |
661 | left = sd.total_len; | |
0f1d344f | 662 | for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) { |
8cefc107 | 663 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
8d020765 AV |
664 | size_t this_len = buf->len; |
665 | ||
0f1d344f PB |
666 | /* zero-length bvecs are not supported, skip them */ |
667 | if (!this_len) | |
668 | continue; | |
669 | this_len = min(this_len, left); | |
8d020765 | 670 | |
fba597db | 671 | ret = pipe_buf_confirm(pipe, buf); |
8d020765 AV |
672 | if (unlikely(ret)) { |
673 | if (ret == -ENODATA) | |
674 | ret = 0; | |
675 | goto done; | |
676 | } | |
677 | ||
664e4078 CH |
678 | bvec_set_page(&array[n], buf->page, this_len, |
679 | buf->offset); | |
8d020765 | 680 | left -= this_len; |
0f1d344f | 681 | n++; |
8d020765 AV |
682 | } |
683 | ||
de4eda9d | 684 | iov_iter_bvec(&from, ITER_SOURCE, array, n, sd.total_len - left); |
abbb6589 | 685 | ret = vfs_iter_write(out, &from, &sd.pos, 0); |
8d020765 AV |
686 | if (ret <= 0) |
687 | break; | |
688 | ||
689 | sd.num_spliced += ret; | |
690 | sd.total_len -= ret; | |
dbe4e192 | 691 | *ppos = sd.pos; |
8d020765 AV |
692 | |
693 | /* dismiss the fully eaten buffers, adjust the partial one */ | |
8cefc107 | 694 | tail = pipe->tail; |
8d020765 | 695 | while (ret) { |
8cefc107 | 696 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
8d020765 | 697 | if (ret >= buf->len) { |
8d020765 AV |
698 | ret -= buf->len; |
699 | buf->len = 0; | |
a779638c | 700 | pipe_buf_release(pipe, buf); |
8cefc107 DH |
701 | tail++; |
702 | pipe->tail = tail; | |
8d020765 AV |
703 | if (pipe->files) |
704 | sd.need_wakeup = true; | |
705 | } else { | |
706 | buf->offset += ret; | |
707 | buf->len -= ret; | |
708 | ret = 0; | |
709 | } | |
710 | } | |
711 | } | |
712 | done: | |
713 | kfree(array); | |
714 | splice_from_pipe_end(pipe, &sd); | |
715 | ||
716 | pipe_unlock(pipe); | |
717 | ||
718 | if (sd.num_spliced) | |
719 | ret = sd.num_spliced; | |
720 | ||
721 | return ret; | |
722 | } | |
723 | ||
724 | EXPORT_SYMBOL(iter_file_splice_write); | |
725 | ||
83f9135b JA |
726 | /** |
727 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 728 | * @pipe: pipe to splice from |
83f9135b | 729 | * @out: socket to write to |
932cc6d4 | 730 | * @ppos: position in @out |
83f9135b JA |
731 | * @len: number of bytes to splice |
732 | * @flags: splice modifier flags | |
733 | * | |
932cc6d4 JA |
734 | * Description: |
735 | * Will send @len bytes from the pipe to a network socket. No data copying | |
736 | * is involved. | |
83f9135b JA |
737 | * |
738 | */ | |
3a326a2c | 739 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 740 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 741 | { |
00522fb4 | 742 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
743 | } |
744 | ||
059a8f37 | 745 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 746 | |
36e2c742 CH |
747 | static int warn_unsupported(struct file *file, const char *op) |
748 | { | |
749 | pr_debug_ratelimited( | |
750 | "splice %s not supported for file %pD4 (pid: %d comm: %.20s)\n", | |
751 | op, file, current->pid, current->comm); | |
752 | return -EINVAL; | |
753 | } | |
754 | ||
83f9135b JA |
755 | /* |
756 | * Attempt to initiate a splice from pipe to file. | |
757 | */ | |
3a326a2c | 758 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 759 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 760 | { |
36e2c742 CH |
761 | if (unlikely(!out->f_op->splice_write)) |
762 | return warn_unsupported(out, "write"); | |
763 | return out->f_op->splice_write(pipe, out, ppos, len, flags); | |
5274f052 JA |
764 | } |
765 | ||
83f9135b JA |
766 | /* |
767 | * Attempt to initiate a splice from a file to a pipe. | |
768 | */ | |
cbb7e577 JA |
769 | static long do_splice_to(struct file *in, loff_t *ppos, |
770 | struct pipe_inode_info *pipe, size_t len, | |
771 | unsigned int flags) | |
5274f052 | 772 | { |
313d64a3 | 773 | unsigned int p_space; |
5274f052 JA |
774 | int ret; |
775 | ||
49570e9b | 776 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
777 | return -EBADF; |
778 | ||
313d64a3 AV |
779 | /* Don't try to read more the pipe has space for. */ |
780 | p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail); | |
781 | len = min_t(size_t, len, p_space << PAGE_SHIFT); | |
782 | ||
cbb7e577 | 783 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
784 | if (unlikely(ret < 0)) |
785 | return ret; | |
786 | ||
03cc0789 AV |
787 | if (unlikely(len > MAX_RW_COUNT)) |
788 | len = MAX_RW_COUNT; | |
789 | ||
36e2c742 CH |
790 | if (unlikely(!in->f_op->splice_read)) |
791 | return warn_unsupported(in, "read"); | |
792 | return in->f_op->splice_read(in, ppos, pipe, len, flags); | |
5274f052 JA |
793 | } |
794 | ||
932cc6d4 JA |
795 | /** |
796 | * splice_direct_to_actor - splices data directly between two non-pipes | |
797 | * @in: file to splice from | |
798 | * @sd: actor information on where to splice to | |
799 | * @actor: handles the data splicing | |
800 | * | |
801 | * Description: | |
802 | * This is a special case helper to splice directly between two | |
803 | * points, without requiring an explicit pipe. Internally an allocated | |
79685b8d | 804 | * pipe is cached in the process, and reused during the lifetime of |
932cc6d4 JA |
805 | * that process. |
806 | * | |
c66ab6fa JA |
807 | */ |
808 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
809 | splice_direct_actor *actor) | |
b92ce558 JA |
810 | { |
811 | struct pipe_inode_info *pipe; | |
812 | long ret, bytes; | |
c66ab6fa | 813 | size_t len; |
0ff28d9f | 814 | int i, flags, more; |
b92ce558 JA |
815 | |
816 | /* | |
97ef77c5 JD |
817 | * We require the input to be seekable, as we don't want to randomly |
818 | * drop data for eg socket -> socket splicing. Use the piped splicing | |
819 | * for that! | |
b92ce558 | 820 | */ |
97ef77c5 | 821 | if (unlikely(!(in->f_mode & FMODE_LSEEK))) |
b92ce558 JA |
822 | return -EINVAL; |
823 | ||
824 | /* | |
825 | * neither in nor out is a pipe, setup an internal pipe attached to | |
826 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
827 | */ | |
828 | pipe = current->splice_pipe; | |
49570e9b | 829 | if (unlikely(!pipe)) { |
7bee130e | 830 | pipe = alloc_pipe_info(); |
b92ce558 JA |
831 | if (!pipe) |
832 | return -ENOMEM; | |
833 | ||
834 | /* | |
835 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 836 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
837 | * PIPE_READERS appropriately. |
838 | */ | |
839 | pipe->readers = 1; | |
840 | ||
841 | current->splice_pipe = pipe; | |
842 | } | |
843 | ||
844 | /* | |
73d62d83 | 845 | * Do the splice. |
b92ce558 JA |
846 | */ |
847 | ret = 0; | |
848 | bytes = 0; | |
c66ab6fa JA |
849 | len = sd->total_len; |
850 | flags = sd->flags; | |
851 | ||
852 | /* | |
853 | * Don't block on output, we have to drain the direct pipe. | |
854 | */ | |
855 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
0ff28d9f | 856 | more = sd->flags & SPLICE_F_MORE; |
b92ce558 | 857 | |
8cefc107 | 858 | WARN_ON_ONCE(!pipe_empty(pipe->head, pipe->tail)); |
17614445 | 859 | |
b92ce558 | 860 | while (len) { |
51a92c0f | 861 | size_t read_len; |
a82c53a0 | 862 | loff_t pos = sd->pos, prev_pos = pos; |
b92ce558 | 863 | |
313d64a3 | 864 | ret = do_splice_to(in, &pos, pipe, len, flags); |
51a92c0f | 865 | if (unlikely(ret <= 0)) |
b92ce558 JA |
866 | goto out_release; |
867 | ||
868 | read_len = ret; | |
c66ab6fa | 869 | sd->total_len = read_len; |
b92ce558 | 870 | |
0ff28d9f CL |
871 | /* |
872 | * If more data is pending, set SPLICE_F_MORE | |
873 | * If this is the last data and SPLICE_F_MORE was not set | |
874 | * initially, clears it. | |
875 | */ | |
876 | if (read_len < len) | |
877 | sd->flags |= SPLICE_F_MORE; | |
878 | else if (!more) | |
879 | sd->flags &= ~SPLICE_F_MORE; | |
b92ce558 JA |
880 | /* |
881 | * NOTE: nonblocking mode only applies to the input. We | |
882 | * must not do the output in nonblocking mode as then we | |
883 | * could get stuck data in the internal pipe: | |
884 | */ | |
c66ab6fa | 885 | ret = actor(pipe, sd); |
a82c53a0 TZ |
886 | if (unlikely(ret <= 0)) { |
887 | sd->pos = prev_pos; | |
b92ce558 | 888 | goto out_release; |
a82c53a0 | 889 | } |
b92ce558 JA |
890 | |
891 | bytes += ret; | |
892 | len -= ret; | |
bcd4f3ac | 893 | sd->pos = pos; |
b92ce558 | 894 | |
a82c53a0 TZ |
895 | if (ret < read_len) { |
896 | sd->pos = prev_pos + ret; | |
51a92c0f | 897 | goto out_release; |
a82c53a0 | 898 | } |
b92ce558 JA |
899 | } |
900 | ||
9e97198d | 901 | done: |
8cefc107 | 902 | pipe->tail = pipe->head = 0; |
80848708 | 903 | file_accessed(in); |
b92ce558 JA |
904 | return bytes; |
905 | ||
906 | out_release: | |
907 | /* | |
908 | * If we did an incomplete transfer we must release | |
909 | * the pipe buffers in question: | |
910 | */ | |
8cefc107 DH |
911 | for (i = 0; i < pipe->ring_size; i++) { |
912 | struct pipe_buffer *buf = &pipe->bufs[i]; | |
b92ce558 | 913 | |
a779638c MS |
914 | if (buf->ops) |
915 | pipe_buf_release(pipe, buf); | |
b92ce558 | 916 | } |
b92ce558 | 917 | |
9e97198d JA |
918 | if (!bytes) |
919 | bytes = ret; | |
c66ab6fa | 920 | |
9e97198d | 921 | goto done; |
c66ab6fa JA |
922 | } |
923 | EXPORT_SYMBOL(splice_direct_to_actor); | |
924 | ||
925 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
926 | struct splice_desc *sd) | |
927 | { | |
6a14b90b | 928 | struct file *file = sd->u.file; |
c66ab6fa | 929 | |
7995bd28 | 930 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
2cb4b05e | 931 | sd->flags); |
c66ab6fa JA |
932 | } |
933 | ||
932cc6d4 JA |
934 | /** |
935 | * do_splice_direct - splices data directly between two files | |
936 | * @in: file to splice from | |
937 | * @ppos: input file offset | |
938 | * @out: file to splice to | |
acdb37c3 | 939 | * @opos: output file offset |
932cc6d4 JA |
940 | * @len: number of bytes to splice |
941 | * @flags: splice modifier flags | |
942 | * | |
943 | * Description: | |
944 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
945 | * doing it in the application would incur an extra system call | |
946 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
947 | * can splice directly through a process-private pipe. | |
948 | * | |
949 | */ | |
c66ab6fa | 950 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
7995bd28 | 951 | loff_t *opos, size_t len, unsigned int flags) |
c66ab6fa JA |
952 | { |
953 | struct splice_desc sd = { | |
954 | .len = len, | |
955 | .total_len = len, | |
956 | .flags = flags, | |
957 | .pos = *ppos, | |
6a14b90b | 958 | .u.file = out, |
7995bd28 | 959 | .opos = opos, |
c66ab6fa | 960 | }; |
51a92c0f | 961 | long ret; |
c66ab6fa | 962 | |
18c67cb9 AV |
963 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
964 | return -EBADF; | |
965 | ||
966 | if (unlikely(out->f_flags & O_APPEND)) | |
967 | return -EINVAL; | |
968 | ||
969 | ret = rw_verify_area(WRITE, out, opos, len); | |
970 | if (unlikely(ret < 0)) | |
971 | return ret; | |
972 | ||
c66ab6fa | 973 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
51a92c0f | 974 | if (ret > 0) |
a82c53a0 | 975 | *ppos = sd.pos; |
51a92c0f | 976 | |
c66ab6fa | 977 | return ret; |
b92ce558 | 978 | } |
1c118596 | 979 | EXPORT_SYMBOL(do_splice_direct); |
b92ce558 | 980 | |
8924feff AV |
981 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) |
982 | { | |
52bce911 LT |
983 | for (;;) { |
984 | if (unlikely(!pipe->readers)) { | |
985 | send_sig(SIGPIPE, current, 0); | |
986 | return -EPIPE; | |
987 | } | |
6718b6f8 | 988 | if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
52bce911 | 989 | return 0; |
8924feff AV |
990 | if (flags & SPLICE_F_NONBLOCK) |
991 | return -EAGAIN; | |
992 | if (signal_pending(current)) | |
993 | return -ERESTARTSYS; | |
472e5b05 | 994 | pipe_wait_writable(pipe); |
8924feff | 995 | } |
8924feff AV |
996 | } |
997 | ||
7c77f0b3 MS |
998 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
999 | struct pipe_inode_info *opipe, | |
1000 | size_t len, unsigned int flags); | |
ddac0d39 | 1001 | |
b964bf53 | 1002 | long splice_file_to_pipe(struct file *in, |
faa97c48 AV |
1003 | struct pipe_inode_info *opipe, |
1004 | loff_t *offset, | |
1005 | size_t len, unsigned int flags) | |
1006 | { | |
1007 | long ret; | |
1008 | ||
1009 | pipe_lock(opipe); | |
1010 | ret = wait_for_space(opipe, flags); | |
1011 | if (!ret) | |
1012 | ret = do_splice_to(in, offset, opipe, len, flags); | |
1013 | pipe_unlock(opipe); | |
1014 | if (ret > 0) | |
1015 | wakeup_pipe_readers(opipe); | |
1016 | return ret; | |
1017 | } | |
1018 | ||
83f9135b JA |
1019 | /* |
1020 | * Determine where to splice to/from. | |
1021 | */ | |
ee6e00c8 JA |
1022 | long do_splice(struct file *in, loff_t *off_in, struct file *out, |
1023 | loff_t *off_out, size_t len, unsigned int flags) | |
5274f052 | 1024 | { |
7c77f0b3 MS |
1025 | struct pipe_inode_info *ipipe; |
1026 | struct pipe_inode_info *opipe; | |
7995bd28 | 1027 | loff_t offset; |
a4514ebd | 1028 | long ret; |
5274f052 | 1029 | |
90da2e3f PB |
1030 | if (unlikely(!(in->f_mode & FMODE_READ) || |
1031 | !(out->f_mode & FMODE_WRITE))) | |
1032 | return -EBADF; | |
1033 | ||
c73be61c DH |
1034 | ipipe = get_pipe_info(in, true); |
1035 | opipe = get_pipe_info(out, true); | |
7c77f0b3 MS |
1036 | |
1037 | if (ipipe && opipe) { | |
1038 | if (off_in || off_out) | |
1039 | return -ESPIPE; | |
1040 | ||
7c77f0b3 MS |
1041 | /* Splicing to self would be fun, but... */ |
1042 | if (ipipe == opipe) | |
1043 | return -EINVAL; | |
1044 | ||
ee5e0011 SK |
1045 | if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
1046 | flags |= SPLICE_F_NONBLOCK; | |
1047 | ||
7c77f0b3 MS |
1048 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1049 | } | |
1050 | ||
1051 | if (ipipe) { | |
529565dc IM |
1052 | if (off_in) |
1053 | return -ESPIPE; | |
b92ce558 | 1054 | if (off_out) { |
19c9a49b | 1055 | if (!(out->f_mode & FMODE_PWRITE)) |
b92ce558 | 1056 | return -EINVAL; |
ee6e00c8 | 1057 | offset = *off_out; |
7995bd28 AV |
1058 | } else { |
1059 | offset = out->f_pos; | |
1060 | } | |
529565dc | 1061 | |
18c67cb9 AV |
1062 | if (unlikely(out->f_flags & O_APPEND)) |
1063 | return -EINVAL; | |
1064 | ||
1065 | ret = rw_verify_area(WRITE, out, &offset, len); | |
1066 | if (unlikely(ret < 0)) | |
1067 | return ret; | |
1068 | ||
ee5e0011 SK |
1069 | if (in->f_flags & O_NONBLOCK) |
1070 | flags |= SPLICE_F_NONBLOCK; | |
1071 | ||
500368f7 | 1072 | file_start_write(out); |
7995bd28 | 1073 | ret = do_splice_from(ipipe, out, &offset, len, flags); |
500368f7 | 1074 | file_end_write(out); |
a4514ebd | 1075 | |
7995bd28 AV |
1076 | if (!off_out) |
1077 | out->f_pos = offset; | |
ee6e00c8 JA |
1078 | else |
1079 | *off_out = offset; | |
a4514ebd JA |
1080 | |
1081 | return ret; | |
529565dc | 1082 | } |
5274f052 | 1083 | |
7c77f0b3 | 1084 | if (opipe) { |
529565dc IM |
1085 | if (off_out) |
1086 | return -ESPIPE; | |
b92ce558 | 1087 | if (off_in) { |
19c9a49b | 1088 | if (!(in->f_mode & FMODE_PREAD)) |
b92ce558 | 1089 | return -EINVAL; |
ee6e00c8 | 1090 | offset = *off_in; |
7995bd28 AV |
1091 | } else { |
1092 | offset = in->f_pos; | |
1093 | } | |
529565dc | 1094 | |
ee5e0011 SK |
1095 | if (out->f_flags & O_NONBLOCK) |
1096 | flags |= SPLICE_F_NONBLOCK; | |
1097 | ||
faa97c48 | 1098 | ret = splice_file_to_pipe(in, opipe, &offset, len, flags); |
7995bd28 AV |
1099 | if (!off_in) |
1100 | in->f_pos = offset; | |
ee6e00c8 JA |
1101 | else |
1102 | *off_in = offset; | |
a4514ebd JA |
1103 | |
1104 | return ret; | |
529565dc | 1105 | } |
5274f052 JA |
1106 | |
1107 | return -EINVAL; | |
1108 | } | |
1109 | ||
ee6e00c8 JA |
1110 | static long __do_splice(struct file *in, loff_t __user *off_in, |
1111 | struct file *out, loff_t __user *off_out, | |
1112 | size_t len, unsigned int flags) | |
1113 | { | |
1114 | struct pipe_inode_info *ipipe; | |
1115 | struct pipe_inode_info *opipe; | |
1116 | loff_t offset, *__off_in = NULL, *__off_out = NULL; | |
1117 | long ret; | |
1118 | ||
1119 | ipipe = get_pipe_info(in, true); | |
1120 | opipe = get_pipe_info(out, true); | |
1121 | ||
1122 | if (ipipe && off_in) | |
1123 | return -ESPIPE; | |
1124 | if (opipe && off_out) | |
1125 | return -ESPIPE; | |
1126 | ||
1127 | if (off_out) { | |
1128 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) | |
1129 | return -EFAULT; | |
1130 | __off_out = &offset; | |
1131 | } | |
1132 | if (off_in) { | |
1133 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) | |
1134 | return -EFAULT; | |
1135 | __off_in = &offset; | |
1136 | } | |
1137 | ||
1138 | ret = do_splice(in, __off_in, out, __off_out, len, flags); | |
1139 | if (ret < 0) | |
1140 | return ret; | |
1141 | ||
1142 | if (__off_out && copy_to_user(off_out, __off_out, sizeof(loff_t))) | |
1143 | return -EFAULT; | |
1144 | if (__off_in && copy_to_user(off_in, __off_in, sizeof(loff_t))) | |
1145 | return -EFAULT; | |
1146 | ||
1147 | return ret; | |
1148 | } | |
1149 | ||
79fddc4e AV |
1150 | static int iter_to_pipe(struct iov_iter *from, |
1151 | struct pipe_inode_info *pipe, | |
1152 | unsigned flags) | |
912d35f8 | 1153 | { |
79fddc4e AV |
1154 | struct pipe_buffer buf = { |
1155 | .ops = &user_page_pipe_buf_ops, | |
1156 | .flags = flags | |
1157 | }; | |
1158 | size_t total = 0; | |
1159 | int ret = 0; | |
79fddc4e | 1160 | |
7d690c15 | 1161 | while (iov_iter_count(from)) { |
79fddc4e | 1162 | struct page *pages[16]; |
7d690c15 | 1163 | ssize_t left; |
db85a9eb | 1164 | size_t start; |
7d690c15 | 1165 | int i, n; |
db85a9eb | 1166 | |
7d690c15 AV |
1167 | left = iov_iter_get_pages2(from, pages, ~0UL, 16, &start); |
1168 | if (left <= 0) { | |
1169 | ret = left; | |
79fddc4e AV |
1170 | break; |
1171 | } | |
db85a9eb | 1172 | |
7d690c15 AV |
1173 | n = DIV_ROUND_UP(left + start, PAGE_SIZE); |
1174 | for (i = 0; i < n; i++) { | |
1175 | int size = min_t(int, left, PAGE_SIZE - start); | |
1176 | ||
1177 | buf.page = pages[i]; | |
1178 | buf.offset = start; | |
1179 | buf.len = size; | |
1180 | ret = add_to_pipe(pipe, &buf); | |
1181 | if (unlikely(ret < 0)) { | |
1182 | iov_iter_revert(from, left); | |
1183 | // this one got dropped by add_to_pipe() | |
1184 | while (++i < n) | |
1185 | put_page(pages[i]); | |
1186 | goto out; | |
79fddc4e | 1187 | } |
7d690c15 AV |
1188 | total += ret; |
1189 | left -= size; | |
1190 | start = 0; | |
912d35f8 | 1191 | } |
912d35f8 | 1192 | } |
7d690c15 | 1193 | out: |
79fddc4e | 1194 | return total ? total : ret; |
912d35f8 JA |
1195 | } |
1196 | ||
6a14b90b JA |
1197 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1198 | struct splice_desc *sd) | |
1199 | { | |
6130f531 AV |
1200 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
1201 | return n == sd->len ? n : -EFAULT; | |
6a14b90b JA |
1202 | } |
1203 | ||
1204 | /* | |
1205 | * For lack of a better implementation, implement vmsplice() to userspace | |
1206 | * as a simple copy of the pipes pages to the user iov. | |
1207 | */ | |
87a3002a AV |
1208 | static long vmsplice_to_user(struct file *file, struct iov_iter *iter, |
1209 | unsigned int flags) | |
6a14b90b | 1210 | { |
c73be61c | 1211 | struct pipe_inode_info *pipe = get_pipe_info(file, true); |
87a3002a AV |
1212 | struct splice_desc sd = { |
1213 | .total_len = iov_iter_count(iter), | |
1214 | .flags = flags, | |
1215 | .u.data = iter | |
1216 | }; | |
1217 | long ret = 0; | |
6a14b90b | 1218 | |
6a14b90b JA |
1219 | if (!pipe) |
1220 | return -EBADF; | |
1221 | ||
345995fa AV |
1222 | if (sd.total_len) { |
1223 | pipe_lock(pipe); | |
1224 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1225 | pipe_unlock(pipe); | |
1226 | } | |
6a14b90b JA |
1227 | |
1228 | return ret; | |
1229 | } | |
1230 | ||
912d35f8 JA |
1231 | /* |
1232 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1233 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1234 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1235 | */ |
87a3002a AV |
1236 | static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter, |
1237 | unsigned int flags) | |
912d35f8 | 1238 | { |
ddac0d39 | 1239 | struct pipe_inode_info *pipe; |
87a3002a | 1240 | long ret = 0; |
79fddc4e AV |
1241 | unsigned buf_flag = 0; |
1242 | ||
1243 | if (flags & SPLICE_F_GIFT) | |
1244 | buf_flag = PIPE_BUF_FLAG_GIFT; | |
912d35f8 | 1245 | |
c73be61c | 1246 | pipe = get_pipe_info(file, true); |
ddac0d39 | 1247 | if (!pipe) |
912d35f8 | 1248 | return -EBADF; |
912d35f8 | 1249 | |
8924feff AV |
1250 | pipe_lock(pipe); |
1251 | ret = wait_for_space(pipe, flags); | |
79fddc4e | 1252 | if (!ret) |
87a3002a | 1253 | ret = iter_to_pipe(iter, pipe, buf_flag); |
8924feff AV |
1254 | pipe_unlock(pipe); |
1255 | if (ret > 0) | |
1256 | wakeup_pipe_readers(pipe); | |
35f3d14d | 1257 | return ret; |
912d35f8 JA |
1258 | } |
1259 | ||
87a3002a AV |
1260 | static int vmsplice_type(struct fd f, int *type) |
1261 | { | |
1262 | if (!f.file) | |
1263 | return -EBADF; | |
1264 | if (f.file->f_mode & FMODE_WRITE) { | |
de4eda9d | 1265 | *type = ITER_SOURCE; |
87a3002a | 1266 | } else if (f.file->f_mode & FMODE_READ) { |
de4eda9d | 1267 | *type = ITER_DEST; |
87a3002a AV |
1268 | } else { |
1269 | fdput(f); | |
1270 | return -EBADF; | |
1271 | } | |
1272 | return 0; | |
1273 | } | |
1274 | ||
6a14b90b JA |
1275 | /* |
1276 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1277 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1278 | * operation that can be supported without any funky alignment restrictions | |
1279 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1280 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1281 | * solutions for that: | |
1282 | * | |
1283 | * - memcpy() the data internally, at which point we might as well just | |
1284 | * do a regular read() on the buffer anyway. | |
1285 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1286 | * has restriction limitations on both ends of the pipe). | |
1287 | * | |
1288 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1289 | * | |
1290 | */ | |
87a3002a | 1291 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, uiov, |
30cfe4ef DB |
1292 | unsigned long, nr_segs, unsigned int, flags) |
1293 | { | |
87a3002a AV |
1294 | struct iovec iovstack[UIO_FASTIOV]; |
1295 | struct iovec *iov = iovstack; | |
1296 | struct iov_iter iter; | |
87e5e6da | 1297 | ssize_t error; |
87a3002a AV |
1298 | struct fd f; |
1299 | int type; | |
1300 | ||
598b3cec CH |
1301 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1302 | return -EINVAL; | |
1303 | ||
87a3002a AV |
1304 | f = fdget(fd); |
1305 | error = vmsplice_type(f, &type); | |
1306 | if (error) | |
1307 | return error; | |
1308 | ||
1309 | error = import_iovec(type, uiov, nr_segs, | |
1310 | ARRAY_SIZE(iovstack), &iov, &iter); | |
598b3cec CH |
1311 | if (error < 0) |
1312 | goto out_fdput; | |
30cfe4ef | 1313 | |
598b3cec CH |
1314 | if (!iov_iter_count(&iter)) |
1315 | error = 0; | |
de4eda9d | 1316 | else if (type == ITER_SOURCE) |
598b3cec CH |
1317 | error = vmsplice_to_pipe(f.file, &iter, flags); |
1318 | else | |
1319 | error = vmsplice_to_user(f.file, &iter, flags); | |
87a3002a | 1320 | |
598b3cec CH |
1321 | kfree(iov); |
1322 | out_fdput: | |
87a3002a AV |
1323 | fdput(f); |
1324 | return error; | |
76b021d0 | 1325 | } |
76b021d0 | 1326 | |
836f92ad HC |
1327 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1328 | int, fd_out, loff_t __user *, off_out, | |
1329 | size_t, len, unsigned int, flags) | |
5274f052 | 1330 | { |
2903ff01 | 1331 | struct fd in, out; |
5274f052 | 1332 | long error; |
5274f052 JA |
1333 | |
1334 | if (unlikely(!len)) | |
1335 | return 0; | |
1336 | ||
3d6ea290 AV |
1337 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1338 | return -EINVAL; | |
1339 | ||
5274f052 | 1340 | error = -EBADF; |
2903ff01 AV |
1341 | in = fdget(fd_in); |
1342 | if (in.file) { | |
90da2e3f PB |
1343 | out = fdget(fd_out); |
1344 | if (out.file) { | |
ee6e00c8 JA |
1345 | error = __do_splice(in.file, off_in, out.file, off_out, |
1346 | len, flags); | |
90da2e3f | 1347 | fdput(out); |
5274f052 | 1348 | } |
2903ff01 | 1349 | fdput(in); |
5274f052 | 1350 | } |
5274f052 JA |
1351 | return error; |
1352 | } | |
70524490 | 1353 | |
aadd06e5 JA |
1354 | /* |
1355 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1356 | * return an appropriate error. | |
1357 | */ | |
7c77f0b3 | 1358 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1359 | { |
1360 | int ret; | |
1361 | ||
1362 | /* | |
8cefc107 | 1363 | * Check the pipe occupancy without the inode lock first. This function |
aadd06e5 JA |
1364 | * is speculative anyways, so missing one is ok. |
1365 | */ | |
8cefc107 | 1366 | if (!pipe_empty(pipe->head, pipe->tail)) |
aadd06e5 JA |
1367 | return 0; |
1368 | ||
1369 | ret = 0; | |
61e0d47c | 1370 | pipe_lock(pipe); |
aadd06e5 | 1371 | |
8cefc107 | 1372 | while (pipe_empty(pipe->head, pipe->tail)) { |
aadd06e5 JA |
1373 | if (signal_pending(current)) { |
1374 | ret = -ERESTARTSYS; | |
1375 | break; | |
1376 | } | |
1377 | if (!pipe->writers) | |
1378 | break; | |
a28c8b9d LT |
1379 | if (flags & SPLICE_F_NONBLOCK) { |
1380 | ret = -EAGAIN; | |
1381 | break; | |
aadd06e5 | 1382 | } |
472e5b05 | 1383 | pipe_wait_readable(pipe); |
aadd06e5 JA |
1384 | } |
1385 | ||
61e0d47c | 1386 | pipe_unlock(pipe); |
aadd06e5 JA |
1387 | return ret; |
1388 | } | |
1389 | ||
1390 | /* | |
1391 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1392 | * return an appropriate error. | |
1393 | */ | |
7c77f0b3 | 1394 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1395 | { |
1396 | int ret; | |
1397 | ||
1398 | /* | |
8cefc107 | 1399 | * Check pipe occupancy without the inode lock first. This function |
aadd06e5 JA |
1400 | * is speculative anyways, so missing one is ok. |
1401 | */ | |
566d1362 | 1402 | if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
aadd06e5 JA |
1403 | return 0; |
1404 | ||
1405 | ret = 0; | |
61e0d47c | 1406 | pipe_lock(pipe); |
aadd06e5 | 1407 | |
6718b6f8 | 1408 | while (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) { |
aadd06e5 JA |
1409 | if (!pipe->readers) { |
1410 | send_sig(SIGPIPE, current, 0); | |
1411 | ret = -EPIPE; | |
1412 | break; | |
1413 | } | |
1414 | if (flags & SPLICE_F_NONBLOCK) { | |
1415 | ret = -EAGAIN; | |
1416 | break; | |
1417 | } | |
1418 | if (signal_pending(current)) { | |
1419 | ret = -ERESTARTSYS; | |
1420 | break; | |
1421 | } | |
472e5b05 | 1422 | pipe_wait_writable(pipe); |
aadd06e5 JA |
1423 | } |
1424 | ||
61e0d47c | 1425 | pipe_unlock(pipe); |
aadd06e5 JA |
1426 | return ret; |
1427 | } | |
1428 | ||
7c77f0b3 MS |
1429 | /* |
1430 | * Splice contents of ipipe to opipe. | |
1431 | */ | |
1432 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1433 | struct pipe_inode_info *opipe, | |
1434 | size_t len, unsigned int flags) | |
1435 | { | |
1436 | struct pipe_buffer *ibuf, *obuf; | |
8cefc107 DH |
1437 | unsigned int i_head, o_head; |
1438 | unsigned int i_tail, o_tail; | |
1439 | unsigned int i_mask, o_mask; | |
1440 | int ret = 0; | |
7c77f0b3 MS |
1441 | bool input_wakeup = false; |
1442 | ||
1443 | ||
1444 | retry: | |
1445 | ret = ipipe_prep(ipipe, flags); | |
1446 | if (ret) | |
1447 | return ret; | |
1448 | ||
1449 | ret = opipe_prep(opipe, flags); | |
1450 | if (ret) | |
1451 | return ret; | |
1452 | ||
1453 | /* | |
1454 | * Potential ABBA deadlock, work around it by ordering lock | |
1455 | * grabbing by pipe info address. Otherwise two different processes | |
1456 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1457 | */ | |
1458 | pipe_double_lock(ipipe, opipe); | |
1459 | ||
8cefc107 DH |
1460 | i_tail = ipipe->tail; |
1461 | i_mask = ipipe->ring_size - 1; | |
1462 | o_head = opipe->head; | |
1463 | o_mask = opipe->ring_size - 1; | |
1464 | ||
7c77f0b3 | 1465 | do { |
8cefc107 DH |
1466 | size_t o_len; |
1467 | ||
7c77f0b3 MS |
1468 | if (!opipe->readers) { |
1469 | send_sig(SIGPIPE, current, 0); | |
1470 | if (!ret) | |
1471 | ret = -EPIPE; | |
1472 | break; | |
1473 | } | |
1474 | ||
8cefc107 DH |
1475 | i_head = ipipe->head; |
1476 | o_tail = opipe->tail; | |
1477 | ||
1478 | if (pipe_empty(i_head, i_tail) && !ipipe->writers) | |
7c77f0b3 MS |
1479 | break; |
1480 | ||
1481 | /* | |
1482 | * Cannot make any progress, because either the input | |
1483 | * pipe is empty or the output pipe is full. | |
1484 | */ | |
8cefc107 | 1485 | if (pipe_empty(i_head, i_tail) || |
6718b6f8 | 1486 | pipe_full(o_head, o_tail, opipe->max_usage)) { |
7c77f0b3 MS |
1487 | /* Already processed some buffers, break */ |
1488 | if (ret) | |
1489 | break; | |
1490 | ||
1491 | if (flags & SPLICE_F_NONBLOCK) { | |
1492 | ret = -EAGAIN; | |
1493 | break; | |
1494 | } | |
1495 | ||
1496 | /* | |
1497 | * We raced with another reader/writer and haven't | |
1498 | * managed to process any buffers. A zero return | |
1499 | * value means EOF, so retry instead. | |
1500 | */ | |
1501 | pipe_unlock(ipipe); | |
1502 | pipe_unlock(opipe); | |
1503 | goto retry; | |
1504 | } | |
1505 | ||
8cefc107 DH |
1506 | ibuf = &ipipe->bufs[i_tail & i_mask]; |
1507 | obuf = &opipe->bufs[o_head & o_mask]; | |
7c77f0b3 MS |
1508 | |
1509 | if (len >= ibuf->len) { | |
1510 | /* | |
1511 | * Simply move the whole buffer from ipipe to opipe | |
1512 | */ | |
1513 | *obuf = *ibuf; | |
1514 | ibuf->ops = NULL; | |
8cefc107 DH |
1515 | i_tail++; |
1516 | ipipe->tail = i_tail; | |
7c77f0b3 | 1517 | input_wakeup = true; |
8cefc107 DH |
1518 | o_len = obuf->len; |
1519 | o_head++; | |
1520 | opipe->head = o_head; | |
7c77f0b3 MS |
1521 | } else { |
1522 | /* | |
1523 | * Get a reference to this pipe buffer, | |
1524 | * so we can copy the contents over. | |
1525 | */ | |
15fab63e MW |
1526 | if (!pipe_buf_get(ipipe, ibuf)) { |
1527 | if (ret == 0) | |
1528 | ret = -EFAULT; | |
1529 | break; | |
1530 | } | |
7c77f0b3 MS |
1531 | *obuf = *ibuf; |
1532 | ||
1533 | /* | |
f6dd9755 | 1534 | * Don't inherit the gift and merge flags, we need to |
7c77f0b3 MS |
1535 | * prevent multiple steals of this page. |
1536 | */ | |
1537 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
f6dd9755 | 1538 | obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
a0ce2f0a | 1539 | |
7c77f0b3 | 1540 | obuf->len = len; |
8cefc107 DH |
1541 | ibuf->offset += len; |
1542 | ibuf->len -= len; | |
1543 | o_len = len; | |
1544 | o_head++; | |
1545 | opipe->head = o_head; | |
7c77f0b3 | 1546 | } |
8cefc107 DH |
1547 | ret += o_len; |
1548 | len -= o_len; | |
7c77f0b3 MS |
1549 | } while (len); |
1550 | ||
1551 | pipe_unlock(ipipe); | |
1552 | pipe_unlock(opipe); | |
1553 | ||
1554 | /* | |
1555 | * If we put data in the output pipe, wakeup any potential readers. | |
1556 | */ | |
825cdcb1 NK |
1557 | if (ret > 0) |
1558 | wakeup_pipe_readers(opipe); | |
1559 | ||
7c77f0b3 MS |
1560 | if (input_wakeup) |
1561 | wakeup_pipe_writers(ipipe); | |
1562 | ||
1563 | return ret; | |
1564 | } | |
1565 | ||
70524490 JA |
1566 | /* |
1567 | * Link contents of ipipe to opipe. | |
1568 | */ | |
1569 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1570 | struct pipe_inode_info *opipe, | |
1571 | size_t len, unsigned int flags) | |
1572 | { | |
1573 | struct pipe_buffer *ibuf, *obuf; | |
8cefc107 DH |
1574 | unsigned int i_head, o_head; |
1575 | unsigned int i_tail, o_tail; | |
1576 | unsigned int i_mask, o_mask; | |
1577 | int ret = 0; | |
70524490 JA |
1578 | |
1579 | /* | |
1580 | * Potential ABBA deadlock, work around it by ordering lock | |
61e0d47c | 1581 | * grabbing by pipe info address. Otherwise two different processes |
70524490 JA |
1582 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1583 | */ | |
61e0d47c | 1584 | pipe_double_lock(ipipe, opipe); |
70524490 | 1585 | |
8cefc107 DH |
1586 | i_tail = ipipe->tail; |
1587 | i_mask = ipipe->ring_size - 1; | |
1588 | o_head = opipe->head; | |
1589 | o_mask = opipe->ring_size - 1; | |
1590 | ||
aadd06e5 | 1591 | do { |
70524490 JA |
1592 | if (!opipe->readers) { |
1593 | send_sig(SIGPIPE, current, 0); | |
1594 | if (!ret) | |
1595 | ret = -EPIPE; | |
1596 | break; | |
1597 | } | |
70524490 | 1598 | |
8cefc107 DH |
1599 | i_head = ipipe->head; |
1600 | o_tail = opipe->tail; | |
1601 | ||
aadd06e5 | 1602 | /* |
8cefc107 | 1603 | * If we have iterated all input buffers or run out of |
aadd06e5 JA |
1604 | * output room, break. |
1605 | */ | |
8cefc107 | 1606 | if (pipe_empty(i_head, i_tail) || |
6718b6f8 | 1607 | pipe_full(o_head, o_tail, opipe->max_usage)) |
aadd06e5 | 1608 | break; |
70524490 | 1609 | |
8cefc107 DH |
1610 | ibuf = &ipipe->bufs[i_tail & i_mask]; |
1611 | obuf = &opipe->bufs[o_head & o_mask]; | |
70524490 JA |
1612 | |
1613 | /* | |
aadd06e5 JA |
1614 | * Get a reference to this pipe buffer, |
1615 | * so we can copy the contents over. | |
70524490 | 1616 | */ |
15fab63e MW |
1617 | if (!pipe_buf_get(ipipe, ibuf)) { |
1618 | if (ret == 0) | |
1619 | ret = -EFAULT; | |
1620 | break; | |
1621 | } | |
aadd06e5 | 1622 | |
aadd06e5 JA |
1623 | *obuf = *ibuf; |
1624 | ||
2a27250e | 1625 | /* |
f6dd9755 CH |
1626 | * Don't inherit the gift and merge flag, we need to prevent |
1627 | * multiple steals of this page. | |
2a27250e | 1628 | */ |
aadd06e5 | 1629 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
f6dd9755 | 1630 | obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
a0ce2f0a | 1631 | |
aadd06e5 JA |
1632 | if (obuf->len > len) |
1633 | obuf->len = len; | |
aadd06e5 JA |
1634 | ret += obuf->len; |
1635 | len -= obuf->len; | |
8cefc107 DH |
1636 | |
1637 | o_head++; | |
1638 | opipe->head = o_head; | |
1639 | i_tail++; | |
aadd06e5 | 1640 | } while (len); |
70524490 | 1641 | |
61e0d47c MS |
1642 | pipe_unlock(ipipe); |
1643 | pipe_unlock(opipe); | |
70524490 | 1644 | |
aadd06e5 JA |
1645 | /* |
1646 | * If we put data in the output pipe, wakeup any potential readers. | |
1647 | */ | |
825cdcb1 NK |
1648 | if (ret > 0) |
1649 | wakeup_pipe_readers(opipe); | |
70524490 JA |
1650 | |
1651 | return ret; | |
1652 | } | |
1653 | ||
1654 | /* | |
1655 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1656 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1657 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1658 | * applicable one is SPLICE_F_NONBLOCK. | |
1659 | */ | |
9dafdfc2 | 1660 | long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags) |
70524490 | 1661 | { |
c73be61c DH |
1662 | struct pipe_inode_info *ipipe = get_pipe_info(in, true); |
1663 | struct pipe_inode_info *opipe = get_pipe_info(out, true); | |
aadd06e5 | 1664 | int ret = -EINVAL; |
70524490 | 1665 | |
90da2e3f PB |
1666 | if (unlikely(!(in->f_mode & FMODE_READ) || |
1667 | !(out->f_mode & FMODE_WRITE))) | |
1668 | return -EBADF; | |
1669 | ||
70524490 | 1670 | /* |
aadd06e5 JA |
1671 | * Duplicate the contents of ipipe to opipe without actually |
1672 | * copying the data. | |
70524490 | 1673 | */ |
aadd06e5 | 1674 | if (ipipe && opipe && ipipe != opipe) { |
ee5e0011 SK |
1675 | if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
1676 | flags |= SPLICE_F_NONBLOCK; | |
1677 | ||
aadd06e5 JA |
1678 | /* |
1679 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1680 | * ordering doesn't really matter. | |
1681 | */ | |
7c77f0b3 | 1682 | ret = ipipe_prep(ipipe, flags); |
aadd06e5 | 1683 | if (!ret) { |
7c77f0b3 | 1684 | ret = opipe_prep(opipe, flags); |
02cf01ae | 1685 | if (!ret) |
aadd06e5 | 1686 | ret = link_pipe(ipipe, opipe, len, flags); |
aadd06e5 JA |
1687 | } |
1688 | } | |
70524490 | 1689 | |
aadd06e5 | 1690 | return ret; |
70524490 JA |
1691 | } |
1692 | ||
836f92ad | 1693 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
70524490 | 1694 | { |
90da2e3f | 1695 | struct fd in, out; |
2903ff01 | 1696 | int error; |
70524490 | 1697 | |
3d6ea290 AV |
1698 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1699 | return -EINVAL; | |
1700 | ||
70524490 JA |
1701 | if (unlikely(!len)) |
1702 | return 0; | |
1703 | ||
1704 | error = -EBADF; | |
2903ff01 AV |
1705 | in = fdget(fdin); |
1706 | if (in.file) { | |
90da2e3f PB |
1707 | out = fdget(fdout); |
1708 | if (out.file) { | |
1709 | error = do_tee(in.file, out.file, len, flags); | |
1710 | fdput(out); | |
70524490 | 1711 | } |
2903ff01 | 1712 | fdput(in); |
70524490 JA |
1713 | } |
1714 | ||
1715 | return error; | |
1716 | } |