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> |
983652c6 | 33 | #include <linux/fsnotify.h> |
29ce2058 | 34 | #include <linux/security.h> |
5a0e3ad6 | 35 | #include <linux/gfp.h> |
35f9c09f | 36 | #include <linux/socket.h> |
174cd4b1 IM |
37 | #include <linux/sched/signal.h> |
38 | ||
06ae43f3 | 39 | #include "internal.h" |
5274f052 | 40 | |
0f99fc51 JA |
41 | /* |
42 | * Splice doesn't support FMODE_NOWAIT. Since pipes may set this flag to | |
43 | * indicate they support non-blocking reads or writes, we must clear it | |
44 | * here if set to avoid blocking other users of this pipe if splice is | |
45 | * being done on it. | |
46 | */ | |
47 | static noinline void noinline pipe_clear_nowait(struct file *file) | |
48 | { | |
49 | fmode_t fmode = READ_ONCE(file->f_mode); | |
50 | ||
51 | do { | |
52 | if (!(fmode & FMODE_NOWAIT)) | |
53 | break; | |
54 | } while (!try_cmpxchg(&file->f_mode, &fmode, fmode & ~FMODE_NOWAIT)); | |
55 | } | |
56 | ||
83f9135b JA |
57 | /* |
58 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
59 | * a vm helper function, it's already simplified quite a bit by the | |
60 | * addition of remove_mapping(). If success is returned, the caller may | |
61 | * attempt to reuse this page for another destination. | |
62 | */ | |
c928f642 CH |
63 | static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
64 | struct pipe_buffer *buf) | |
5abc97aa | 65 | { |
5100da38 | 66 | struct folio *folio = page_folio(buf->page); |
9e94cd4f | 67 | struct address_space *mapping; |
5abc97aa | 68 | |
b9ccad2e | 69 | folio_lock(folio); |
9e0267c2 | 70 | |
b9ccad2e | 71 | mapping = folio_mapping(folio); |
9e94cd4f | 72 | if (mapping) { |
b9ccad2e | 73 | WARN_ON(!folio_test_uptodate(folio)); |
5abc97aa | 74 | |
9e94cd4f JA |
75 | /* |
76 | * At least for ext2 with nobh option, we need to wait on | |
b9ccad2e | 77 | * writeback completing on this folio, since we'll remove it |
9e94cd4f | 78 | * from the pagecache. Otherwise truncate wont wait on the |
b9ccad2e | 79 | * folio, allowing the disk blocks to be reused by someone else |
9e94cd4f JA |
80 | * before we actually wrote our data to them. fs corruption |
81 | * ensues. | |
82 | */ | |
b9ccad2e | 83 | folio_wait_writeback(folio); |
ad8d6f0a | 84 | |
b9ccad2e MWO |
85 | if (folio_has_private(folio) && |
86 | !filemap_release_folio(folio, GFP_KERNEL)) | |
ca39d651 | 87 | goto out_unlock; |
4f6f0bd2 | 88 | |
9e94cd4f JA |
89 | /* |
90 | * If we succeeded in removing the mapping, set LRU flag | |
91 | * and return good. | |
92 | */ | |
5100da38 | 93 | if (remove_mapping(mapping, folio)) { |
9e94cd4f | 94 | buf->flags |= PIPE_BUF_FLAG_LRU; |
c928f642 | 95 | return true; |
9e94cd4f | 96 | } |
9e0267c2 | 97 | } |
5abc97aa | 98 | |
9e94cd4f | 99 | /* |
b9ccad2e | 100 | * Raced with truncate or failed to remove folio from current |
9e94cd4f JA |
101 | * address space, unlock and return failure. |
102 | */ | |
ca39d651 | 103 | out_unlock: |
b9ccad2e | 104 | folio_unlock(folio); |
c928f642 | 105 | return false; |
5abc97aa JA |
106 | } |
107 | ||
76ad4d11 | 108 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
5274f052 JA |
109 | struct pipe_buffer *buf) |
110 | { | |
09cbfeaf | 111 | put_page(buf->page); |
1432873a | 112 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
113 | } |
114 | ||
0845718d JA |
115 | /* |
116 | * Check whether the contents of buf is OK to access. Since the content | |
117 | * is a page cache page, IO may be in flight. | |
118 | */ | |
cac36bb0 JA |
119 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
120 | struct pipe_buffer *buf) | |
5274f052 JA |
121 | { |
122 | struct page *page = buf->page; | |
49d0b21b | 123 | int err; |
5274f052 JA |
124 | |
125 | if (!PageUptodate(page)) { | |
49d0b21b JA |
126 | lock_page(page); |
127 | ||
128 | /* | |
129 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 130 | * splice, if this is the first page. |
49d0b21b JA |
131 | */ |
132 | if (!page->mapping) { | |
133 | err = -ENODATA; | |
134 | goto error; | |
135 | } | |
5274f052 | 136 | |
49d0b21b | 137 | /* |
73d62d83 | 138 | * Uh oh, read-error from disk. |
49d0b21b JA |
139 | */ |
140 | if (!PageUptodate(page)) { | |
141 | err = -EIO; | |
142 | goto error; | |
143 | } | |
144 | ||
145 | /* | |
f84d7519 | 146 | * Page is ok afterall, we are done. |
49d0b21b | 147 | */ |
5274f052 | 148 | unlock_page(page); |
5274f052 JA |
149 | } |
150 | ||
f84d7519 | 151 | return 0; |
49d0b21b JA |
152 | error: |
153 | unlock_page(page); | |
f84d7519 | 154 | return err; |
70524490 JA |
155 | } |
156 | ||
708e3508 | 157 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
c928f642 CH |
158 | .confirm = page_cache_pipe_buf_confirm, |
159 | .release = page_cache_pipe_buf_release, | |
160 | .try_steal = page_cache_pipe_buf_try_steal, | |
161 | .get = generic_pipe_buf_get, | |
5274f052 JA |
162 | }; |
163 | ||
c928f642 CH |
164 | static bool user_page_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
165 | struct pipe_buffer *buf) | |
912d35f8 | 166 | { |
7afa6fd0 | 167 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
c928f642 | 168 | return false; |
7afa6fd0 | 169 | |
1432873a | 170 | buf->flags |= PIPE_BUF_FLAG_LRU; |
c928f642 | 171 | return generic_pipe_buf_try_steal(pipe, buf); |
912d35f8 JA |
172 | } |
173 | ||
d4c3cca9 | 174 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
c928f642 CH |
175 | .release = page_cache_pipe_buf_release, |
176 | .try_steal = user_page_pipe_buf_try_steal, | |
177 | .get = generic_pipe_buf_get, | |
912d35f8 JA |
178 | }; |
179 | ||
825cdcb1 NK |
180 | static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
181 | { | |
182 | smp_mb(); | |
0ddad21d LT |
183 | if (waitqueue_active(&pipe->rd_wait)) |
184 | wake_up_interruptible(&pipe->rd_wait); | |
825cdcb1 NK |
185 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
186 | } | |
187 | ||
932cc6d4 JA |
188 | /** |
189 | * splice_to_pipe - fill passed data into a pipe | |
190 | * @pipe: pipe to fill | |
191 | * @spd: data to fill | |
192 | * | |
193 | * Description: | |
79685b8d | 194 | * @spd contains a map of pages and len/offset tuples, along with |
932cc6d4 JA |
195 | * the struct pipe_buf_operations associated with these pages. This |
196 | * function will link that data to the pipe. | |
197 | * | |
83f9135b | 198 | */ |
d6b29d7c JA |
199 | ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
200 | struct splice_pipe_desc *spd) | |
5274f052 | 201 | { |
00de00bd | 202 | unsigned int spd_pages = spd->nr_pages; |
8cefc107 DH |
203 | unsigned int tail = pipe->tail; |
204 | unsigned int head = pipe->head; | |
205 | unsigned int mask = pipe->ring_size - 1; | |
8924feff | 206 | int ret = 0, page_nr = 0; |
5274f052 | 207 | |
d6785d91 RV |
208 | if (!spd_pages) |
209 | return 0; | |
210 | ||
8924feff AV |
211 | if (unlikely(!pipe->readers)) { |
212 | send_sig(SIGPIPE, current, 0); | |
213 | ret = -EPIPE; | |
214 | goto out; | |
215 | } | |
5274f052 | 216 | |
6718b6f8 | 217 | while (!pipe_full(head, tail, pipe->max_usage)) { |
8cefc107 | 218 | struct pipe_buffer *buf = &pipe->bufs[head & mask]; |
5274f052 | 219 | |
8924feff AV |
220 | buf->page = spd->pages[page_nr]; |
221 | buf->offset = spd->partial[page_nr].offset; | |
222 | buf->len = spd->partial[page_nr].len; | |
223 | buf->private = spd->partial[page_nr].private; | |
224 | buf->ops = spd->ops; | |
5a81e6a1 | 225 | buf->flags = 0; |
5274f052 | 226 | |
8cefc107 DH |
227 | head++; |
228 | pipe->head = head; | |
8924feff AV |
229 | page_nr++; |
230 | ret += buf->len; | |
29e35094 | 231 | |
8924feff | 232 | if (!--spd->nr_pages) |
5274f052 | 233 | break; |
5274f052 JA |
234 | } |
235 | ||
8924feff AV |
236 | if (!ret) |
237 | ret = -EAGAIN; | |
5274f052 | 238 | |
8924feff | 239 | out: |
00de00bd | 240 | while (page_nr < spd_pages) |
bbdfc2f7 | 241 | spd->spd_release(spd, page_nr++); |
5274f052 JA |
242 | |
243 | return ret; | |
244 | } | |
2b514574 | 245 | EXPORT_SYMBOL_GPL(splice_to_pipe); |
5274f052 | 246 | |
79fddc4e AV |
247 | ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
248 | { | |
8cefc107 DH |
249 | unsigned int head = pipe->head; |
250 | unsigned int tail = pipe->tail; | |
251 | unsigned int mask = pipe->ring_size - 1; | |
79fddc4e AV |
252 | int ret; |
253 | ||
254 | if (unlikely(!pipe->readers)) { | |
255 | send_sig(SIGPIPE, current, 0); | |
256 | ret = -EPIPE; | |
6718b6f8 | 257 | } else if (pipe_full(head, tail, pipe->max_usage)) { |
79fddc4e AV |
258 | ret = -EAGAIN; |
259 | } else { | |
8cefc107 DH |
260 | pipe->bufs[head & mask] = *buf; |
261 | pipe->head = head + 1; | |
79fddc4e AV |
262 | return buf->len; |
263 | } | |
a779638c | 264 | pipe_buf_release(pipe, buf); |
79fddc4e AV |
265 | return ret; |
266 | } | |
267 | EXPORT_SYMBOL(add_to_pipe); | |
268 | ||
35f3d14d JA |
269 | /* |
270 | * Check if we need to grow the arrays holding pages and partial page | |
271 | * descriptions. | |
272 | */ | |
047fe360 | 273 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
35f3d14d | 274 | { |
6718b6f8 | 275 | unsigned int max_usage = READ_ONCE(pipe->max_usage); |
047fe360 | 276 | |
8cefc107 DH |
277 | spd->nr_pages_max = max_usage; |
278 | if (max_usage <= PIPE_DEF_BUFFERS) | |
35f3d14d JA |
279 | return 0; |
280 | ||
8cefc107 DH |
281 | spd->pages = kmalloc_array(max_usage, sizeof(struct page *), GFP_KERNEL); |
282 | spd->partial = kmalloc_array(max_usage, sizeof(struct partial_page), | |
6da2ec56 | 283 | GFP_KERNEL); |
35f3d14d JA |
284 | |
285 | if (spd->pages && spd->partial) | |
286 | return 0; | |
287 | ||
288 | kfree(spd->pages); | |
289 | kfree(spd->partial); | |
290 | return -ENOMEM; | |
291 | } | |
292 | ||
047fe360 | 293 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
35f3d14d | 294 | { |
047fe360 | 295 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
35f3d14d JA |
296 | return; |
297 | ||
298 | kfree(spd->pages); | |
299 | kfree(spd->partial); | |
300 | } | |
301 | ||
9eee8bd8 DH |
302 | /** |
303 | * copy_splice_read - Copy data from a file and splice the copy into a pipe | |
304 | * @in: The file to read from | |
305 | * @ppos: Pointer to the file position to read from | |
306 | * @pipe: The pipe to splice into | |
307 | * @len: The amount to splice | |
308 | * @flags: The SPLICE_F_* flags | |
309 | * | |
310 | * This function allocates a bunch of pages sufficient to hold the requested | |
311 | * amount of data (but limited by the remaining pipe capacity), passes it to | |
312 | * the file's ->read_iter() to read into and then splices the used pages into | |
313 | * the pipe. | |
314 | * | |
315 | * Return: On success, the number of bytes read will be returned and *@ppos | |
316 | * will be updated if appropriate; 0 will be returned if there is no more data | |
317 | * to be read; -EAGAIN will be returned if the pipe had no space, and some | |
318 | * other negative error code will be returned on error. A short read may occur | |
319 | * if the pipe has insufficient space, we reach the end of the data or we hit a | |
320 | * hole. | |
33b3b041 | 321 | */ |
69df79a4 DH |
322 | ssize_t copy_splice_read(struct file *in, loff_t *ppos, |
323 | struct pipe_inode_info *pipe, | |
324 | size_t len, unsigned int flags) | |
33b3b041 DH |
325 | { |
326 | struct iov_iter to; | |
327 | struct bio_vec *bv; | |
328 | struct kiocb kiocb; | |
329 | struct page **pages; | |
330 | ssize_t ret; | |
e69f37bc | 331 | size_t used, npages, chunk, remain, keep = 0; |
33b3b041 DH |
332 | int i; |
333 | ||
334 | /* Work out how much data we can actually add into the pipe */ | |
335 | used = pipe_occupancy(pipe->head, pipe->tail); | |
336 | npages = max_t(ssize_t, pipe->max_usage - used, 0); | |
337 | len = min_t(size_t, len, npages * PAGE_SIZE); | |
338 | npages = DIV_ROUND_UP(len, PAGE_SIZE); | |
339 | ||
340 | bv = kzalloc(array_size(npages, sizeof(bv[0])) + | |
341 | array_size(npages, sizeof(struct page *)), GFP_KERNEL); | |
342 | if (!bv) | |
343 | return -ENOMEM; | |
344 | ||
e69f37bc | 345 | pages = (struct page **)(bv + npages); |
33b3b041 DH |
346 | npages = alloc_pages_bulk_array(GFP_USER, npages, pages); |
347 | if (!npages) { | |
348 | kfree(bv); | |
349 | return -ENOMEM; | |
350 | } | |
351 | ||
352 | remain = len = min_t(size_t, len, npages * PAGE_SIZE); | |
353 | ||
354 | for (i = 0; i < npages; i++) { | |
355 | chunk = min_t(size_t, PAGE_SIZE, remain); | |
356 | bv[i].bv_page = pages[i]; | |
357 | bv[i].bv_offset = 0; | |
358 | bv[i].bv_len = chunk; | |
359 | remain -= chunk; | |
360 | } | |
361 | ||
362 | /* Do the I/O */ | |
363 | iov_iter_bvec(&to, ITER_DEST, bv, npages, len); | |
364 | init_sync_kiocb(&kiocb, in); | |
365 | kiocb.ki_pos = *ppos; | |
366 | ret = call_read_iter(in, &kiocb, &to); | |
367 | ||
33b3b041 | 368 | if (ret > 0) { |
e69f37bc | 369 | keep = DIV_ROUND_UP(ret, PAGE_SIZE); |
33b3b041 | 370 | *ppos = kiocb.ki_pos; |
33b3b041 DH |
371 | } |
372 | ||
2e82f6c3 CH |
373 | /* |
374 | * Callers of ->splice_read() expect -EAGAIN on "can't put anything in | |
375 | * there", rather than -EFAULT. | |
376 | */ | |
377 | if (ret == -EFAULT) | |
378 | ret = -EAGAIN; | |
379 | ||
33b3b041 | 380 | /* Free any pages that didn't get touched at all. */ |
e69f37bc DH |
381 | if (keep < npages) |
382 | release_pages(pages + keep, npages - keep); | |
33b3b041 DH |
383 | |
384 | /* Push the remaining pages into the pipe. */ | |
e69f37bc DH |
385 | remain = ret; |
386 | for (i = 0; i < keep; i++) { | |
33b3b041 DH |
387 | struct pipe_buffer *buf = pipe_head_buf(pipe); |
388 | ||
389 | chunk = min_t(size_t, remain, PAGE_SIZE); | |
390 | *buf = (struct pipe_buffer) { | |
391 | .ops = &default_pipe_buf_ops, | |
392 | .page = bv[i].bv_page, | |
393 | .offset = 0, | |
394 | .len = chunk, | |
395 | }; | |
396 | pipe->head++; | |
397 | remain -= chunk; | |
398 | } | |
399 | ||
400 | kfree(bv); | |
401 | return ret; | |
402 | } | |
69df79a4 | 403 | EXPORT_SYMBOL(copy_splice_read); |
33b3b041 | 404 | |
241699cd | 405 | const struct pipe_buf_operations default_pipe_buf_ops = { |
c928f642 CH |
406 | .release = generic_pipe_buf_release, |
407 | .try_steal = generic_pipe_buf_try_steal, | |
408 | .get = generic_pipe_buf_get, | |
6818173b MS |
409 | }; |
410 | ||
28a625cb MS |
411 | /* Pipe buffer operations for a socket and similar. */ |
412 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { | |
c928f642 CH |
413 | .release = generic_pipe_buf_release, |
414 | .get = generic_pipe_buf_get, | |
28a625cb MS |
415 | }; |
416 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); | |
417 | ||
5274f052 | 418 | /* |
4f6f0bd2 | 419 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 420 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 421 | */ |
76ad4d11 | 422 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
423 | struct pipe_buffer *buf, struct splice_desc *sd) |
424 | { | |
6a14b90b | 425 | struct file *file = sd->u.file; |
5274f052 | 426 | loff_t pos = sd->pos; |
a8adbe37 | 427 | int more; |
5274f052 | 428 | |
72c2d531 | 429 | if (!likely(file->f_op->sendpage)) |
a8adbe37 MM |
430 | return -EINVAL; |
431 | ||
35f9c09f | 432 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
ae62ca7b | 433 | |
8cefc107 DH |
434 | if (sd->len < sd->total_len && |
435 | pipe_occupancy(pipe->head, pipe->tail) > 1) | |
35f9c09f | 436 | more |= MSG_SENDPAGE_NOTLAST; |
ae62ca7b | 437 | |
a8adbe37 MM |
438 | return file->f_op->sendpage(file, buf->page, buf->offset, |
439 | sd->len, &pos, more); | |
5274f052 JA |
440 | } |
441 | ||
b3c2d2dd MS |
442 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
443 | { | |
444 | smp_mb(); | |
0ddad21d LT |
445 | if (waitqueue_active(&pipe->wr_wait)) |
446 | wake_up_interruptible(&pipe->wr_wait); | |
b3c2d2dd MS |
447 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
448 | } | |
449 | ||
932cc6d4 | 450 | /** |
b3c2d2dd | 451 | * splice_from_pipe_feed - feed available data from a pipe to a file |
932cc6d4 JA |
452 | * @pipe: pipe to splice from |
453 | * @sd: information to @actor | |
454 | * @actor: handler that splices the data | |
455 | * | |
456 | * Description: | |
b3c2d2dd MS |
457 | * This function loops over the pipe and calls @actor to do the |
458 | * actual moving of a single struct pipe_buffer to the desired | |
459 | * destination. It returns when there's no more buffers left in | |
460 | * the pipe or if the requested number of bytes (@sd->total_len) | |
461 | * have been copied. It returns a positive number (one) if the | |
462 | * pipe needs to be filled with more data, zero if the required | |
463 | * number of bytes have been copied and -errno on error. | |
932cc6d4 | 464 | * |
b3c2d2dd MS |
465 | * This, together with splice_from_pipe_{begin,end,next}, may be |
466 | * used to implement the functionality of __splice_from_pipe() when | |
467 | * locking is required around copying the pipe buffers to the | |
468 | * destination. | |
83f9135b | 469 | */ |
96f9bc8f | 470 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
b3c2d2dd | 471 | splice_actor *actor) |
5274f052 | 472 | { |
8cefc107 DH |
473 | unsigned int head = pipe->head; |
474 | unsigned int tail = pipe->tail; | |
475 | unsigned int mask = pipe->ring_size - 1; | |
b3c2d2dd | 476 | int ret; |
5274f052 | 477 | |
ec057595 | 478 | while (!pipe_empty(head, tail)) { |
8cefc107 | 479 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
5274f052 | 480 | |
b3c2d2dd MS |
481 | sd->len = buf->len; |
482 | if (sd->len > sd->total_len) | |
483 | sd->len = sd->total_len; | |
5274f052 | 484 | |
fba597db | 485 | ret = pipe_buf_confirm(pipe, buf); |
a8adbe37 | 486 | if (unlikely(ret)) { |
b3c2d2dd MS |
487 | if (ret == -ENODATA) |
488 | ret = 0; | |
489 | return ret; | |
490 | } | |
a8adbe37 MM |
491 | |
492 | ret = actor(pipe, buf, sd); | |
493 | if (ret <= 0) | |
494 | return ret; | |
495 | ||
b3c2d2dd MS |
496 | buf->offset += ret; |
497 | buf->len -= ret; | |
498 | ||
499 | sd->num_spliced += ret; | |
500 | sd->len -= ret; | |
501 | sd->pos += ret; | |
502 | sd->total_len -= ret; | |
503 | ||
504 | if (!buf->len) { | |
a779638c | 505 | pipe_buf_release(pipe, buf); |
8cefc107 DH |
506 | tail++; |
507 | pipe->tail = tail; | |
6447a3cf | 508 | if (pipe->files) |
b3c2d2dd MS |
509 | sd->need_wakeup = true; |
510 | } | |
5274f052 | 511 | |
b3c2d2dd MS |
512 | if (!sd->total_len) |
513 | return 0; | |
514 | } | |
5274f052 | 515 | |
b3c2d2dd MS |
516 | return 1; |
517 | } | |
5274f052 | 518 | |
d1a819a2 LT |
519 | /* We know we have a pipe buffer, but maybe it's empty? */ |
520 | static inline bool eat_empty_buffer(struct pipe_inode_info *pipe) | |
521 | { | |
522 | unsigned int tail = pipe->tail; | |
523 | unsigned int mask = pipe->ring_size - 1; | |
524 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; | |
525 | ||
526 | if (unlikely(!buf->len)) { | |
527 | pipe_buf_release(pipe, buf); | |
528 | pipe->tail = tail+1; | |
529 | return true; | |
530 | } | |
531 | ||
532 | return false; | |
533 | } | |
534 | ||
b3c2d2dd MS |
535 | /** |
536 | * splice_from_pipe_next - wait for some data to splice from | |
537 | * @pipe: pipe to splice from | |
538 | * @sd: information about the splice operation | |
539 | * | |
540 | * Description: | |
541 | * This function will wait for some data and return a positive | |
542 | * value (one) if pipe buffers are available. It will return zero | |
543 | * or -errno if no more data needs to be spliced. | |
544 | */ | |
96f9bc8f | 545 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd | 546 | { |
c725bfce JK |
547 | /* |
548 | * Check for signal early to make process killable when there are | |
549 | * always buffers available | |
550 | */ | |
551 | if (signal_pending(current)) | |
552 | return -ERESTARTSYS; | |
553 | ||
d1a819a2 | 554 | repeat: |
8cefc107 | 555 | while (pipe_empty(pipe->head, pipe->tail)) { |
b3c2d2dd MS |
556 | if (!pipe->writers) |
557 | return 0; | |
016b661e | 558 | |
a28c8b9d | 559 | if (sd->num_spliced) |
b3c2d2dd | 560 | return 0; |
73d62d83 | 561 | |
b3c2d2dd MS |
562 | if (sd->flags & SPLICE_F_NONBLOCK) |
563 | return -EAGAIN; | |
5274f052 | 564 | |
b3c2d2dd MS |
565 | if (signal_pending(current)) |
566 | return -ERESTARTSYS; | |
5274f052 | 567 | |
b3c2d2dd MS |
568 | if (sd->need_wakeup) { |
569 | wakeup_pipe_writers(pipe); | |
570 | sd->need_wakeup = false; | |
5274f052 JA |
571 | } |
572 | ||
472e5b05 | 573 | pipe_wait_readable(pipe); |
b3c2d2dd | 574 | } |
29e35094 | 575 | |
d1a819a2 LT |
576 | if (eat_empty_buffer(pipe)) |
577 | goto repeat; | |
578 | ||
b3c2d2dd MS |
579 | return 1; |
580 | } | |
5274f052 | 581 | |
b3c2d2dd MS |
582 | /** |
583 | * splice_from_pipe_begin - start splicing from pipe | |
b80901bb | 584 | * @sd: information about the splice operation |
b3c2d2dd MS |
585 | * |
586 | * Description: | |
587 | * This function should be called before a loop containing | |
588 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
589 | * initialize the necessary fields of @sd. | |
590 | */ | |
96f9bc8f | 591 | static void splice_from_pipe_begin(struct splice_desc *sd) |
b3c2d2dd MS |
592 | { |
593 | sd->num_spliced = 0; | |
594 | sd->need_wakeup = false; | |
595 | } | |
5274f052 | 596 | |
b3c2d2dd MS |
597 | /** |
598 | * splice_from_pipe_end - finish splicing from pipe | |
599 | * @pipe: pipe to splice from | |
600 | * @sd: information about the splice operation | |
601 | * | |
602 | * Description: | |
603 | * This function will wake up pipe writers if necessary. It should | |
604 | * be called after a loop containing splice_from_pipe_next() and | |
605 | * splice_from_pipe_feed(). | |
606 | */ | |
96f9bc8f | 607 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd MS |
608 | { |
609 | if (sd->need_wakeup) | |
610 | wakeup_pipe_writers(pipe); | |
611 | } | |
5274f052 | 612 | |
b3c2d2dd MS |
613 | /** |
614 | * __splice_from_pipe - splice data from a pipe to given actor | |
615 | * @pipe: pipe to splice from | |
616 | * @sd: information to @actor | |
617 | * @actor: handler that splices the data | |
618 | * | |
619 | * Description: | |
620 | * This function does little more than loop over the pipe and call | |
621 | * @actor to do the actual moving of a single struct pipe_buffer to | |
622 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
623 | * pipe_to_user. | |
624 | * | |
625 | */ | |
626 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
627 | splice_actor *actor) | |
628 | { | |
629 | int ret; | |
5274f052 | 630 | |
b3c2d2dd MS |
631 | splice_from_pipe_begin(sd); |
632 | do { | |
c2489e07 | 633 | cond_resched(); |
b3c2d2dd MS |
634 | ret = splice_from_pipe_next(pipe, sd); |
635 | if (ret > 0) | |
636 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
637 | } while (ret > 0); | |
638 | splice_from_pipe_end(pipe, sd); | |
639 | ||
640 | return sd->num_spliced ? sd->num_spliced : ret; | |
5274f052 | 641 | } |
40bee44e | 642 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 643 | |
932cc6d4 JA |
644 | /** |
645 | * splice_from_pipe - splice data from a pipe to a file | |
646 | * @pipe: pipe to splice from | |
647 | * @out: file to splice to | |
648 | * @ppos: position in @out | |
649 | * @len: how many bytes to splice | |
650 | * @flags: splice modifier flags | |
651 | * @actor: handler that splices the data | |
652 | * | |
653 | * Description: | |
2933970b | 654 | * See __splice_from_pipe. This function locks the pipe inode, |
932cc6d4 JA |
655 | * otherwise it's identical to __splice_from_pipe(). |
656 | * | |
657 | */ | |
6da61809 MF |
658 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
659 | loff_t *ppos, size_t len, unsigned int flags, | |
660 | splice_actor *actor) | |
661 | { | |
662 | ssize_t ret; | |
c66ab6fa JA |
663 | struct splice_desc sd = { |
664 | .total_len = len, | |
665 | .flags = flags, | |
666 | .pos = *ppos, | |
6a14b90b | 667 | .u.file = out, |
c66ab6fa | 668 | }; |
6da61809 | 669 | |
61e0d47c | 670 | pipe_lock(pipe); |
c66ab6fa | 671 | ret = __splice_from_pipe(pipe, &sd, actor); |
61e0d47c | 672 | pipe_unlock(pipe); |
6da61809 MF |
673 | |
674 | return ret; | |
675 | } | |
676 | ||
8d020765 AV |
677 | /** |
678 | * iter_file_splice_write - splice data from a pipe to a file | |
679 | * @pipe: pipe info | |
680 | * @out: file to write to | |
681 | * @ppos: position in @out | |
682 | * @len: number of bytes to splice | |
683 | * @flags: splice modifier flags | |
684 | * | |
685 | * Description: | |
686 | * Will either move or copy pages (determined by @flags options) from | |
687 | * the given pipe inode to the given file. | |
688 | * This one is ->write_iter-based. | |
689 | * | |
690 | */ | |
691 | ssize_t | |
692 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
693 | loff_t *ppos, size_t len, unsigned int flags) | |
694 | { | |
695 | struct splice_desc sd = { | |
696 | .total_len = len, | |
697 | .flags = flags, | |
698 | .pos = *ppos, | |
699 | .u.file = out, | |
700 | }; | |
6718b6f8 | 701 | int nbufs = pipe->max_usage; |
8d020765 AV |
702 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), |
703 | GFP_KERNEL); | |
704 | ssize_t ret; | |
705 | ||
706 | if (unlikely(!array)) | |
707 | return -ENOMEM; | |
708 | ||
709 | pipe_lock(pipe); | |
710 | ||
711 | splice_from_pipe_begin(&sd); | |
712 | while (sd.total_len) { | |
713 | struct iov_iter from; | |
ec057595 | 714 | unsigned int head, tail, mask; |
8d020765 | 715 | size_t left; |
8cefc107 | 716 | int n; |
8d020765 AV |
717 | |
718 | ret = splice_from_pipe_next(pipe, &sd); | |
719 | if (ret <= 0) | |
720 | break; | |
721 | ||
6718b6f8 | 722 | if (unlikely(nbufs < pipe->max_usage)) { |
8d020765 | 723 | kfree(array); |
6718b6f8 | 724 | nbufs = pipe->max_usage; |
8d020765 AV |
725 | array = kcalloc(nbufs, sizeof(struct bio_vec), |
726 | GFP_KERNEL); | |
727 | if (!array) { | |
728 | ret = -ENOMEM; | |
729 | break; | |
730 | } | |
731 | } | |
732 | ||
ec057595 LT |
733 | head = pipe->head; |
734 | tail = pipe->tail; | |
735 | mask = pipe->ring_size - 1; | |
736 | ||
8d020765 AV |
737 | /* build the vector */ |
738 | left = sd.total_len; | |
0f1d344f | 739 | for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) { |
8cefc107 | 740 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
8d020765 AV |
741 | size_t this_len = buf->len; |
742 | ||
0f1d344f PB |
743 | /* zero-length bvecs are not supported, skip them */ |
744 | if (!this_len) | |
745 | continue; | |
746 | this_len = min(this_len, left); | |
8d020765 | 747 | |
fba597db | 748 | ret = pipe_buf_confirm(pipe, buf); |
8d020765 AV |
749 | if (unlikely(ret)) { |
750 | if (ret == -ENODATA) | |
751 | ret = 0; | |
752 | goto done; | |
753 | } | |
754 | ||
664e4078 CH |
755 | bvec_set_page(&array[n], buf->page, this_len, |
756 | buf->offset); | |
8d020765 | 757 | left -= this_len; |
0f1d344f | 758 | n++; |
8d020765 AV |
759 | } |
760 | ||
de4eda9d | 761 | iov_iter_bvec(&from, ITER_SOURCE, array, n, sd.total_len - left); |
abbb6589 | 762 | ret = vfs_iter_write(out, &from, &sd.pos, 0); |
8d020765 AV |
763 | if (ret <= 0) |
764 | break; | |
765 | ||
766 | sd.num_spliced += ret; | |
767 | sd.total_len -= ret; | |
dbe4e192 | 768 | *ppos = sd.pos; |
8d020765 AV |
769 | |
770 | /* dismiss the fully eaten buffers, adjust the partial one */ | |
8cefc107 | 771 | tail = pipe->tail; |
8d020765 | 772 | while (ret) { |
8cefc107 | 773 | struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
8d020765 | 774 | if (ret >= buf->len) { |
8d020765 AV |
775 | ret -= buf->len; |
776 | buf->len = 0; | |
a779638c | 777 | pipe_buf_release(pipe, buf); |
8cefc107 DH |
778 | tail++; |
779 | pipe->tail = tail; | |
8d020765 AV |
780 | if (pipe->files) |
781 | sd.need_wakeup = true; | |
782 | } else { | |
783 | buf->offset += ret; | |
784 | buf->len -= ret; | |
785 | ret = 0; | |
786 | } | |
787 | } | |
788 | } | |
789 | done: | |
790 | kfree(array); | |
791 | splice_from_pipe_end(pipe, &sd); | |
792 | ||
793 | pipe_unlock(pipe); | |
794 | ||
795 | if (sd.num_spliced) | |
796 | ret = sd.num_spliced; | |
797 | ||
798 | return ret; | |
799 | } | |
800 | ||
801 | EXPORT_SYMBOL(iter_file_splice_write); | |
802 | ||
83f9135b JA |
803 | /** |
804 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 805 | * @pipe: pipe to splice from |
83f9135b | 806 | * @out: socket to write to |
932cc6d4 | 807 | * @ppos: position in @out |
83f9135b JA |
808 | * @len: number of bytes to splice |
809 | * @flags: splice modifier flags | |
810 | * | |
932cc6d4 JA |
811 | * Description: |
812 | * Will send @len bytes from the pipe to a network socket. No data copying | |
813 | * is involved. | |
83f9135b JA |
814 | * |
815 | */ | |
3a326a2c | 816 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 817 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 818 | { |
00522fb4 | 819 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
820 | } |
821 | ||
059a8f37 | 822 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 823 | |
36e2c742 CH |
824 | static int warn_unsupported(struct file *file, const char *op) |
825 | { | |
826 | pr_debug_ratelimited( | |
827 | "splice %s not supported for file %pD4 (pid: %d comm: %.20s)\n", | |
828 | op, file, current->pid, current->comm); | |
829 | return -EINVAL; | |
830 | } | |
831 | ||
83f9135b JA |
832 | /* |
833 | * Attempt to initiate a splice from pipe to file. | |
834 | */ | |
3a326a2c | 835 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 836 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 837 | { |
36e2c742 CH |
838 | if (unlikely(!out->f_op->splice_write)) |
839 | return warn_unsupported(out, "write"); | |
840 | return out->f_op->splice_write(pipe, out, ppos, len, flags); | |
5274f052 JA |
841 | } |
842 | ||
6a3f30b8 DH |
843 | /** |
844 | * vfs_splice_read - Read data from a file and splice it into a pipe | |
845 | * @in: File to splice from | |
846 | * @ppos: Input file offset | |
847 | * @pipe: Pipe to splice to | |
848 | * @len: Number of bytes to splice | |
849 | * @flags: Splice modifier flags (SPLICE_F_*) | |
850 | * | |
851 | * Splice the requested amount of data from the input file to the pipe. This | |
852 | * is synchronous as the caller must hold the pipe lock across the entire | |
853 | * operation. | |
854 | * | |
855 | * If successful, it returns the amount of data spliced, 0 if it hit the EOF or | |
856 | * a hole and a negative error code otherwise. | |
83f9135b | 857 | */ |
6a3f30b8 DH |
858 | long vfs_splice_read(struct file *in, loff_t *ppos, |
859 | struct pipe_inode_info *pipe, size_t len, | |
860 | unsigned int flags) | |
5274f052 | 861 | { |
313d64a3 | 862 | unsigned int p_space; |
5274f052 JA |
863 | int ret; |
864 | ||
49570e9b | 865 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 | 866 | return -EBADF; |
123856f0 DH |
867 | if (!len) |
868 | return 0; | |
5274f052 | 869 | |
313d64a3 AV |
870 | /* Don't try to read more the pipe has space for. */ |
871 | p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail); | |
872 | len = min_t(size_t, len, p_space << PAGE_SHIFT); | |
873 | ||
cbb7e577 | 874 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
875 | if (unlikely(ret < 0)) |
876 | return ret; | |
877 | ||
03cc0789 AV |
878 | if (unlikely(len > MAX_RW_COUNT)) |
879 | len = MAX_RW_COUNT; | |
880 | ||
36e2c742 CH |
881 | if (unlikely(!in->f_op->splice_read)) |
882 | return warn_unsupported(in, "read"); | |
aa3dbde8 | 883 | /* |
b85930a0 DH |
884 | * O_DIRECT and DAX don't deal with the pagecache, so we allocate a |
885 | * buffer, copy into it and splice that into the pipe. | |
aa3dbde8 | 886 | */ |
b85930a0 | 887 | if ((in->f_flags & O_DIRECT) || IS_DAX(in->f_mapping->host)) |
aa3dbde8 | 888 | return copy_splice_read(in, ppos, pipe, len, flags); |
36e2c742 | 889 | return in->f_op->splice_read(in, ppos, pipe, len, flags); |
5274f052 | 890 | } |
6a3f30b8 | 891 | EXPORT_SYMBOL_GPL(vfs_splice_read); |
5274f052 | 892 | |
932cc6d4 JA |
893 | /** |
894 | * splice_direct_to_actor - splices data directly between two non-pipes | |
895 | * @in: file to splice from | |
896 | * @sd: actor information on where to splice to | |
897 | * @actor: handles the data splicing | |
898 | * | |
899 | * Description: | |
900 | * This is a special case helper to splice directly between two | |
901 | * points, without requiring an explicit pipe. Internally an allocated | |
79685b8d | 902 | * pipe is cached in the process, and reused during the lifetime of |
932cc6d4 JA |
903 | * that process. |
904 | * | |
c66ab6fa JA |
905 | */ |
906 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
907 | splice_direct_actor *actor) | |
b92ce558 JA |
908 | { |
909 | struct pipe_inode_info *pipe; | |
910 | long ret, bytes; | |
c66ab6fa | 911 | size_t len; |
0ff28d9f | 912 | int i, flags, more; |
b92ce558 JA |
913 | |
914 | /* | |
97ef77c5 JD |
915 | * We require the input to be seekable, as we don't want to randomly |
916 | * drop data for eg socket -> socket splicing. Use the piped splicing | |
917 | * for that! | |
b92ce558 | 918 | */ |
97ef77c5 | 919 | if (unlikely(!(in->f_mode & FMODE_LSEEK))) |
b92ce558 JA |
920 | return -EINVAL; |
921 | ||
922 | /* | |
923 | * neither in nor out is a pipe, setup an internal pipe attached to | |
924 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
925 | */ | |
926 | pipe = current->splice_pipe; | |
49570e9b | 927 | if (unlikely(!pipe)) { |
7bee130e | 928 | pipe = alloc_pipe_info(); |
b92ce558 JA |
929 | if (!pipe) |
930 | return -ENOMEM; | |
931 | ||
932 | /* | |
933 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 934 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
935 | * PIPE_READERS appropriately. |
936 | */ | |
937 | pipe->readers = 1; | |
938 | ||
939 | current->splice_pipe = pipe; | |
940 | } | |
941 | ||
942 | /* | |
73d62d83 | 943 | * Do the splice. |
b92ce558 | 944 | */ |
b92ce558 | 945 | bytes = 0; |
c66ab6fa JA |
946 | len = sd->total_len; |
947 | flags = sd->flags; | |
948 | ||
949 | /* | |
950 | * Don't block on output, we have to drain the direct pipe. | |
951 | */ | |
952 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
0ff28d9f | 953 | more = sd->flags & SPLICE_F_MORE; |
b92ce558 | 954 | |
8cefc107 | 955 | WARN_ON_ONCE(!pipe_empty(pipe->head, pipe->tail)); |
17614445 | 956 | |
b92ce558 | 957 | while (len) { |
51a92c0f | 958 | size_t read_len; |
a82c53a0 | 959 | loff_t pos = sd->pos, prev_pos = pos; |
b92ce558 | 960 | |
6a3f30b8 | 961 | ret = vfs_splice_read(in, &pos, pipe, len, flags); |
51a92c0f | 962 | if (unlikely(ret <= 0)) |
b92ce558 JA |
963 | goto out_release; |
964 | ||
965 | read_len = ret; | |
c66ab6fa | 966 | sd->total_len = read_len; |
b92ce558 | 967 | |
0ff28d9f CL |
968 | /* |
969 | * If more data is pending, set SPLICE_F_MORE | |
970 | * If this is the last data and SPLICE_F_MORE was not set | |
971 | * initially, clears it. | |
972 | */ | |
973 | if (read_len < len) | |
974 | sd->flags |= SPLICE_F_MORE; | |
975 | else if (!more) | |
976 | sd->flags &= ~SPLICE_F_MORE; | |
b92ce558 JA |
977 | /* |
978 | * NOTE: nonblocking mode only applies to the input. We | |
979 | * must not do the output in nonblocking mode as then we | |
980 | * could get stuck data in the internal pipe: | |
981 | */ | |
c66ab6fa | 982 | ret = actor(pipe, sd); |
a82c53a0 TZ |
983 | if (unlikely(ret <= 0)) { |
984 | sd->pos = prev_pos; | |
b92ce558 | 985 | goto out_release; |
a82c53a0 | 986 | } |
b92ce558 JA |
987 | |
988 | bytes += ret; | |
989 | len -= ret; | |
bcd4f3ac | 990 | sd->pos = pos; |
b92ce558 | 991 | |
a82c53a0 TZ |
992 | if (ret < read_len) { |
993 | sd->pos = prev_pos + ret; | |
51a92c0f | 994 | goto out_release; |
a82c53a0 | 995 | } |
b92ce558 JA |
996 | } |
997 | ||
9e97198d | 998 | done: |
8cefc107 | 999 | pipe->tail = pipe->head = 0; |
80848708 | 1000 | file_accessed(in); |
b92ce558 JA |
1001 | return bytes; |
1002 | ||
1003 | out_release: | |
1004 | /* | |
1005 | * If we did an incomplete transfer we must release | |
1006 | * the pipe buffers in question: | |
1007 | */ | |
8cefc107 DH |
1008 | for (i = 0; i < pipe->ring_size; i++) { |
1009 | struct pipe_buffer *buf = &pipe->bufs[i]; | |
b92ce558 | 1010 | |
a779638c MS |
1011 | if (buf->ops) |
1012 | pipe_buf_release(pipe, buf); | |
b92ce558 | 1013 | } |
b92ce558 | 1014 | |
9e97198d JA |
1015 | if (!bytes) |
1016 | bytes = ret; | |
c66ab6fa | 1017 | |
9e97198d | 1018 | goto done; |
c66ab6fa JA |
1019 | } |
1020 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1021 | ||
1022 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1023 | struct splice_desc *sd) | |
1024 | { | |
6a14b90b | 1025 | struct file *file = sd->u.file; |
c66ab6fa | 1026 | |
7995bd28 | 1027 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
2cb4b05e | 1028 | sd->flags); |
c66ab6fa JA |
1029 | } |
1030 | ||
932cc6d4 JA |
1031 | /** |
1032 | * do_splice_direct - splices data directly between two files | |
1033 | * @in: file to splice from | |
1034 | * @ppos: input file offset | |
1035 | * @out: file to splice to | |
acdb37c3 | 1036 | * @opos: output file offset |
932cc6d4 JA |
1037 | * @len: number of bytes to splice |
1038 | * @flags: splice modifier flags | |
1039 | * | |
1040 | * Description: | |
1041 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1042 | * doing it in the application would incur an extra system call | |
1043 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1044 | * can splice directly through a process-private pipe. | |
1045 | * | |
1046 | */ | |
c66ab6fa | 1047 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
7995bd28 | 1048 | loff_t *opos, size_t len, unsigned int flags) |
c66ab6fa JA |
1049 | { |
1050 | struct splice_desc sd = { | |
1051 | .len = len, | |
1052 | .total_len = len, | |
1053 | .flags = flags, | |
1054 | .pos = *ppos, | |
6a14b90b | 1055 | .u.file = out, |
7995bd28 | 1056 | .opos = opos, |
c66ab6fa | 1057 | }; |
51a92c0f | 1058 | long ret; |
c66ab6fa | 1059 | |
18c67cb9 AV |
1060 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1061 | return -EBADF; | |
1062 | ||
1063 | if (unlikely(out->f_flags & O_APPEND)) | |
1064 | return -EINVAL; | |
1065 | ||
1066 | ret = rw_verify_area(WRITE, out, opos, len); | |
1067 | if (unlikely(ret < 0)) | |
1068 | return ret; | |
1069 | ||
c66ab6fa | 1070 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
51a92c0f | 1071 | if (ret > 0) |
a82c53a0 | 1072 | *ppos = sd.pos; |
51a92c0f | 1073 | |
c66ab6fa | 1074 | return ret; |
b92ce558 | 1075 | } |
1c118596 | 1076 | EXPORT_SYMBOL(do_splice_direct); |
b92ce558 | 1077 | |
8924feff AV |
1078 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) |
1079 | { | |
52bce911 LT |
1080 | for (;;) { |
1081 | if (unlikely(!pipe->readers)) { | |
1082 | send_sig(SIGPIPE, current, 0); | |
1083 | return -EPIPE; | |
1084 | } | |
6718b6f8 | 1085 | if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
52bce911 | 1086 | return 0; |
8924feff AV |
1087 | if (flags & SPLICE_F_NONBLOCK) |
1088 | return -EAGAIN; | |
1089 | if (signal_pending(current)) | |
1090 | return -ERESTARTSYS; | |
472e5b05 | 1091 | pipe_wait_writable(pipe); |
8924feff | 1092 | } |
8924feff AV |
1093 | } |
1094 | ||
7c77f0b3 MS |
1095 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1096 | struct pipe_inode_info *opipe, | |
1097 | size_t len, unsigned int flags); | |
ddac0d39 | 1098 | |
b964bf53 | 1099 | long splice_file_to_pipe(struct file *in, |
faa97c48 AV |
1100 | struct pipe_inode_info *opipe, |
1101 | loff_t *offset, | |
1102 | size_t len, unsigned int flags) | |
1103 | { | |
1104 | long ret; | |
1105 | ||
1106 | pipe_lock(opipe); | |
1107 | ret = wait_for_space(opipe, flags); | |
1108 | if (!ret) | |
6a3f30b8 | 1109 | ret = vfs_splice_read(in, offset, opipe, len, flags); |
faa97c48 AV |
1110 | pipe_unlock(opipe); |
1111 | if (ret > 0) | |
1112 | wakeup_pipe_readers(opipe); | |
1113 | return ret; | |
1114 | } | |
1115 | ||
83f9135b JA |
1116 | /* |
1117 | * Determine where to splice to/from. | |
1118 | */ | |
ee6e00c8 JA |
1119 | long do_splice(struct file *in, loff_t *off_in, struct file *out, |
1120 | loff_t *off_out, size_t len, unsigned int flags) | |
5274f052 | 1121 | { |
7c77f0b3 MS |
1122 | struct pipe_inode_info *ipipe; |
1123 | struct pipe_inode_info *opipe; | |
7995bd28 | 1124 | loff_t offset; |
a4514ebd | 1125 | long ret; |
5274f052 | 1126 | |
90da2e3f PB |
1127 | if (unlikely(!(in->f_mode & FMODE_READ) || |
1128 | !(out->f_mode & FMODE_WRITE))) | |
1129 | return -EBADF; | |
1130 | ||
c73be61c DH |
1131 | ipipe = get_pipe_info(in, true); |
1132 | opipe = get_pipe_info(out, true); | |
7c77f0b3 MS |
1133 | |
1134 | if (ipipe && opipe) { | |
1135 | if (off_in || off_out) | |
1136 | return -ESPIPE; | |
1137 | ||
7c77f0b3 MS |
1138 | /* Splicing to self would be fun, but... */ |
1139 | if (ipipe == opipe) | |
1140 | return -EINVAL; | |
1141 | ||
ee5e0011 SK |
1142 | if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
1143 | flags |= SPLICE_F_NONBLOCK; | |
1144 | ||
7c77f0b3 MS |
1145 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); |
1146 | } | |
1147 | ||
1148 | if (ipipe) { | |
529565dc IM |
1149 | if (off_in) |
1150 | return -ESPIPE; | |
b92ce558 | 1151 | if (off_out) { |
19c9a49b | 1152 | if (!(out->f_mode & FMODE_PWRITE)) |
b92ce558 | 1153 | return -EINVAL; |
ee6e00c8 | 1154 | offset = *off_out; |
7995bd28 AV |
1155 | } else { |
1156 | offset = out->f_pos; | |
1157 | } | |
529565dc | 1158 | |
18c67cb9 AV |
1159 | if (unlikely(out->f_flags & O_APPEND)) |
1160 | return -EINVAL; | |
1161 | ||
1162 | ret = rw_verify_area(WRITE, out, &offset, len); | |
1163 | if (unlikely(ret < 0)) | |
1164 | return ret; | |
1165 | ||
ee5e0011 SK |
1166 | if (in->f_flags & O_NONBLOCK) |
1167 | flags |= SPLICE_F_NONBLOCK; | |
1168 | ||
500368f7 | 1169 | file_start_write(out); |
7995bd28 | 1170 | ret = do_splice_from(ipipe, out, &offset, len, flags); |
500368f7 | 1171 | file_end_write(out); |
a4514ebd | 1172 | |
983652c6 CCC |
1173 | if (ret > 0) |
1174 | fsnotify_modify(out); | |
1175 | ||
7995bd28 AV |
1176 | if (!off_out) |
1177 | out->f_pos = offset; | |
ee6e00c8 JA |
1178 | else |
1179 | *off_out = offset; | |
a4514ebd JA |
1180 | |
1181 | return ret; | |
529565dc | 1182 | } |
5274f052 | 1183 | |
7c77f0b3 | 1184 | if (opipe) { |
529565dc IM |
1185 | if (off_out) |
1186 | return -ESPIPE; | |
b92ce558 | 1187 | if (off_in) { |
19c9a49b | 1188 | if (!(in->f_mode & FMODE_PREAD)) |
b92ce558 | 1189 | return -EINVAL; |
ee6e00c8 | 1190 | offset = *off_in; |
7995bd28 AV |
1191 | } else { |
1192 | offset = in->f_pos; | |
1193 | } | |
529565dc | 1194 | |
ee5e0011 SK |
1195 | if (out->f_flags & O_NONBLOCK) |
1196 | flags |= SPLICE_F_NONBLOCK; | |
1197 | ||
faa97c48 | 1198 | ret = splice_file_to_pipe(in, opipe, &offset, len, flags); |
983652c6 CCC |
1199 | |
1200 | if (ret > 0) | |
1201 | fsnotify_access(in); | |
1202 | ||
7995bd28 AV |
1203 | if (!off_in) |
1204 | in->f_pos = offset; | |
ee6e00c8 JA |
1205 | else |
1206 | *off_in = offset; | |
a4514ebd JA |
1207 | |
1208 | return ret; | |
529565dc | 1209 | } |
5274f052 JA |
1210 | |
1211 | return -EINVAL; | |
1212 | } | |
1213 | ||
ee6e00c8 JA |
1214 | static long __do_splice(struct file *in, loff_t __user *off_in, |
1215 | struct file *out, loff_t __user *off_out, | |
1216 | size_t len, unsigned int flags) | |
1217 | { | |
1218 | struct pipe_inode_info *ipipe; | |
1219 | struct pipe_inode_info *opipe; | |
1220 | loff_t offset, *__off_in = NULL, *__off_out = NULL; | |
1221 | long ret; | |
1222 | ||
1223 | ipipe = get_pipe_info(in, true); | |
1224 | opipe = get_pipe_info(out, true); | |
1225 | ||
0f99fc51 JA |
1226 | if (ipipe) { |
1227 | if (off_in) | |
1228 | return -ESPIPE; | |
1229 | pipe_clear_nowait(in); | |
1230 | } | |
1231 | if (opipe) { | |
1232 | if (off_out) | |
1233 | return -ESPIPE; | |
1234 | pipe_clear_nowait(out); | |
1235 | } | |
ee6e00c8 JA |
1236 | |
1237 | if (off_out) { | |
1238 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) | |
1239 | return -EFAULT; | |
1240 | __off_out = &offset; | |
1241 | } | |
1242 | if (off_in) { | |
1243 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) | |
1244 | return -EFAULT; | |
1245 | __off_in = &offset; | |
1246 | } | |
1247 | ||
1248 | ret = do_splice(in, __off_in, out, __off_out, len, flags); | |
1249 | if (ret < 0) | |
1250 | return ret; | |
1251 | ||
1252 | if (__off_out && copy_to_user(off_out, __off_out, sizeof(loff_t))) | |
1253 | return -EFAULT; | |
1254 | if (__off_in && copy_to_user(off_in, __off_in, sizeof(loff_t))) | |
1255 | return -EFAULT; | |
1256 | ||
1257 | return ret; | |
1258 | } | |
1259 | ||
79fddc4e AV |
1260 | static int iter_to_pipe(struct iov_iter *from, |
1261 | struct pipe_inode_info *pipe, | |
1262 | unsigned flags) | |
912d35f8 | 1263 | { |
79fddc4e AV |
1264 | struct pipe_buffer buf = { |
1265 | .ops = &user_page_pipe_buf_ops, | |
1266 | .flags = flags | |
1267 | }; | |
1268 | size_t total = 0; | |
1269 | int ret = 0; | |
79fddc4e | 1270 | |
7d690c15 | 1271 | while (iov_iter_count(from)) { |
79fddc4e | 1272 | struct page *pages[16]; |
7d690c15 | 1273 | ssize_t left; |
db85a9eb | 1274 | size_t start; |
7d690c15 | 1275 | int i, n; |
db85a9eb | 1276 | |
7d690c15 AV |
1277 | left = iov_iter_get_pages2(from, pages, ~0UL, 16, &start); |
1278 | if (left <= 0) { | |
1279 | ret = left; | |
79fddc4e AV |
1280 | break; |
1281 | } | |
db85a9eb | 1282 | |
7d690c15 AV |
1283 | n = DIV_ROUND_UP(left + start, PAGE_SIZE); |
1284 | for (i = 0; i < n; i++) { | |
1285 | int size = min_t(int, left, PAGE_SIZE - start); | |
1286 | ||
1287 | buf.page = pages[i]; | |
1288 | buf.offset = start; | |
1289 | buf.len = size; | |
1290 | ret = add_to_pipe(pipe, &buf); | |
1291 | if (unlikely(ret < 0)) { | |
1292 | iov_iter_revert(from, left); | |
1293 | // this one got dropped by add_to_pipe() | |
1294 | while (++i < n) | |
1295 | put_page(pages[i]); | |
1296 | goto out; | |
79fddc4e | 1297 | } |
7d690c15 AV |
1298 | total += ret; |
1299 | left -= size; | |
1300 | start = 0; | |
912d35f8 | 1301 | } |
912d35f8 | 1302 | } |
7d690c15 | 1303 | out: |
79fddc4e | 1304 | return total ? total : ret; |
912d35f8 JA |
1305 | } |
1306 | ||
6a14b90b JA |
1307 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1308 | struct splice_desc *sd) | |
1309 | { | |
6130f531 AV |
1310 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
1311 | return n == sd->len ? n : -EFAULT; | |
6a14b90b JA |
1312 | } |
1313 | ||
1314 | /* | |
1315 | * For lack of a better implementation, implement vmsplice() to userspace | |
1316 | * as a simple copy of the pipes pages to the user iov. | |
1317 | */ | |
87a3002a AV |
1318 | static long vmsplice_to_user(struct file *file, struct iov_iter *iter, |
1319 | unsigned int flags) | |
6a14b90b | 1320 | { |
c73be61c | 1321 | struct pipe_inode_info *pipe = get_pipe_info(file, true); |
87a3002a AV |
1322 | struct splice_desc sd = { |
1323 | .total_len = iov_iter_count(iter), | |
1324 | .flags = flags, | |
1325 | .u.data = iter | |
1326 | }; | |
1327 | long ret = 0; | |
6a14b90b | 1328 | |
6a14b90b JA |
1329 | if (!pipe) |
1330 | return -EBADF; | |
1331 | ||
0f99fc51 JA |
1332 | pipe_clear_nowait(file); |
1333 | ||
345995fa AV |
1334 | if (sd.total_len) { |
1335 | pipe_lock(pipe); | |
1336 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1337 | pipe_unlock(pipe); | |
1338 | } | |
6a14b90b JA |
1339 | |
1340 | return ret; | |
1341 | } | |
1342 | ||
912d35f8 JA |
1343 | /* |
1344 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1345 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1346 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1347 | */ |
87a3002a AV |
1348 | static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter, |
1349 | unsigned int flags) | |
912d35f8 | 1350 | { |
ddac0d39 | 1351 | struct pipe_inode_info *pipe; |
87a3002a | 1352 | long ret = 0; |
79fddc4e AV |
1353 | unsigned buf_flag = 0; |
1354 | ||
1355 | if (flags & SPLICE_F_GIFT) | |
1356 | buf_flag = PIPE_BUF_FLAG_GIFT; | |
912d35f8 | 1357 | |
c73be61c | 1358 | pipe = get_pipe_info(file, true); |
ddac0d39 | 1359 | if (!pipe) |
912d35f8 | 1360 | return -EBADF; |
912d35f8 | 1361 | |
0f99fc51 JA |
1362 | pipe_clear_nowait(file); |
1363 | ||
8924feff AV |
1364 | pipe_lock(pipe); |
1365 | ret = wait_for_space(pipe, flags); | |
79fddc4e | 1366 | if (!ret) |
87a3002a | 1367 | ret = iter_to_pipe(iter, pipe, buf_flag); |
8924feff AV |
1368 | pipe_unlock(pipe); |
1369 | if (ret > 0) | |
1370 | wakeup_pipe_readers(pipe); | |
35f3d14d | 1371 | return ret; |
912d35f8 JA |
1372 | } |
1373 | ||
87a3002a AV |
1374 | static int vmsplice_type(struct fd f, int *type) |
1375 | { | |
1376 | if (!f.file) | |
1377 | return -EBADF; | |
1378 | if (f.file->f_mode & FMODE_WRITE) { | |
de4eda9d | 1379 | *type = ITER_SOURCE; |
87a3002a | 1380 | } else if (f.file->f_mode & FMODE_READ) { |
de4eda9d | 1381 | *type = ITER_DEST; |
87a3002a AV |
1382 | } else { |
1383 | fdput(f); | |
1384 | return -EBADF; | |
1385 | } | |
1386 | return 0; | |
1387 | } | |
1388 | ||
6a14b90b JA |
1389 | /* |
1390 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1391 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1392 | * operation that can be supported without any funky alignment restrictions | |
1393 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1394 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1395 | * solutions for that: | |
1396 | * | |
1397 | * - memcpy() the data internally, at which point we might as well just | |
1398 | * do a regular read() on the buffer anyway. | |
1399 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1400 | * has restriction limitations on both ends of the pipe). | |
1401 | * | |
1402 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1403 | * | |
1404 | */ | |
87a3002a | 1405 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, uiov, |
30cfe4ef DB |
1406 | unsigned long, nr_segs, unsigned int, flags) |
1407 | { | |
87a3002a AV |
1408 | struct iovec iovstack[UIO_FASTIOV]; |
1409 | struct iovec *iov = iovstack; | |
1410 | struct iov_iter iter; | |
87e5e6da | 1411 | ssize_t error; |
87a3002a AV |
1412 | struct fd f; |
1413 | int type; | |
1414 | ||
598b3cec CH |
1415 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1416 | return -EINVAL; | |
1417 | ||
87a3002a AV |
1418 | f = fdget(fd); |
1419 | error = vmsplice_type(f, &type); | |
1420 | if (error) | |
1421 | return error; | |
1422 | ||
1423 | error = import_iovec(type, uiov, nr_segs, | |
1424 | ARRAY_SIZE(iovstack), &iov, &iter); | |
598b3cec CH |
1425 | if (error < 0) |
1426 | goto out_fdput; | |
30cfe4ef | 1427 | |
598b3cec CH |
1428 | if (!iov_iter_count(&iter)) |
1429 | error = 0; | |
de4eda9d | 1430 | else if (type == ITER_SOURCE) |
598b3cec CH |
1431 | error = vmsplice_to_pipe(f.file, &iter, flags); |
1432 | else | |
1433 | error = vmsplice_to_user(f.file, &iter, flags); | |
87a3002a | 1434 | |
598b3cec CH |
1435 | kfree(iov); |
1436 | out_fdput: | |
87a3002a AV |
1437 | fdput(f); |
1438 | return error; | |
76b021d0 | 1439 | } |
76b021d0 | 1440 | |
836f92ad HC |
1441 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1442 | int, fd_out, loff_t __user *, off_out, | |
1443 | size_t, len, unsigned int, flags) | |
5274f052 | 1444 | { |
2903ff01 | 1445 | struct fd in, out; |
5274f052 | 1446 | long error; |
5274f052 JA |
1447 | |
1448 | if (unlikely(!len)) | |
1449 | return 0; | |
1450 | ||
3d6ea290 AV |
1451 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1452 | return -EINVAL; | |
1453 | ||
5274f052 | 1454 | error = -EBADF; |
2903ff01 AV |
1455 | in = fdget(fd_in); |
1456 | if (in.file) { | |
90da2e3f PB |
1457 | out = fdget(fd_out); |
1458 | if (out.file) { | |
ee6e00c8 JA |
1459 | error = __do_splice(in.file, off_in, out.file, off_out, |
1460 | len, flags); | |
90da2e3f | 1461 | fdput(out); |
5274f052 | 1462 | } |
2903ff01 | 1463 | fdput(in); |
5274f052 | 1464 | } |
5274f052 JA |
1465 | return error; |
1466 | } | |
70524490 | 1467 | |
aadd06e5 JA |
1468 | /* |
1469 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1470 | * return an appropriate error. | |
1471 | */ | |
7c77f0b3 | 1472 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1473 | { |
1474 | int ret; | |
1475 | ||
1476 | /* | |
8cefc107 | 1477 | * Check the pipe occupancy without the inode lock first. This function |
aadd06e5 JA |
1478 | * is speculative anyways, so missing one is ok. |
1479 | */ | |
8cefc107 | 1480 | if (!pipe_empty(pipe->head, pipe->tail)) |
aadd06e5 JA |
1481 | return 0; |
1482 | ||
1483 | ret = 0; | |
61e0d47c | 1484 | pipe_lock(pipe); |
aadd06e5 | 1485 | |
8cefc107 | 1486 | while (pipe_empty(pipe->head, pipe->tail)) { |
aadd06e5 JA |
1487 | if (signal_pending(current)) { |
1488 | ret = -ERESTARTSYS; | |
1489 | break; | |
1490 | } | |
1491 | if (!pipe->writers) | |
1492 | break; | |
a28c8b9d LT |
1493 | if (flags & SPLICE_F_NONBLOCK) { |
1494 | ret = -EAGAIN; | |
1495 | break; | |
aadd06e5 | 1496 | } |
472e5b05 | 1497 | pipe_wait_readable(pipe); |
aadd06e5 JA |
1498 | } |
1499 | ||
61e0d47c | 1500 | pipe_unlock(pipe); |
aadd06e5 JA |
1501 | return ret; |
1502 | } | |
1503 | ||
1504 | /* | |
1505 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1506 | * return an appropriate error. | |
1507 | */ | |
7c77f0b3 | 1508 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1509 | { |
1510 | int ret; | |
1511 | ||
1512 | /* | |
8cefc107 | 1513 | * Check pipe occupancy without the inode lock first. This function |
aadd06e5 JA |
1514 | * is speculative anyways, so missing one is ok. |
1515 | */ | |
566d1362 | 1516 | if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
aadd06e5 JA |
1517 | return 0; |
1518 | ||
1519 | ret = 0; | |
61e0d47c | 1520 | pipe_lock(pipe); |
aadd06e5 | 1521 | |
6718b6f8 | 1522 | while (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) { |
aadd06e5 JA |
1523 | if (!pipe->readers) { |
1524 | send_sig(SIGPIPE, current, 0); | |
1525 | ret = -EPIPE; | |
1526 | break; | |
1527 | } | |
1528 | if (flags & SPLICE_F_NONBLOCK) { | |
1529 | ret = -EAGAIN; | |
1530 | break; | |
1531 | } | |
1532 | if (signal_pending(current)) { | |
1533 | ret = -ERESTARTSYS; | |
1534 | break; | |
1535 | } | |
472e5b05 | 1536 | pipe_wait_writable(pipe); |
aadd06e5 JA |
1537 | } |
1538 | ||
61e0d47c | 1539 | pipe_unlock(pipe); |
aadd06e5 JA |
1540 | return ret; |
1541 | } | |
1542 | ||
7c77f0b3 MS |
1543 | /* |
1544 | * Splice contents of ipipe to opipe. | |
1545 | */ | |
1546 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1547 | struct pipe_inode_info *opipe, | |
1548 | size_t len, unsigned int flags) | |
1549 | { | |
1550 | struct pipe_buffer *ibuf, *obuf; | |
8cefc107 DH |
1551 | unsigned int i_head, o_head; |
1552 | unsigned int i_tail, o_tail; | |
1553 | unsigned int i_mask, o_mask; | |
1554 | int ret = 0; | |
7c77f0b3 MS |
1555 | bool input_wakeup = false; |
1556 | ||
1557 | ||
1558 | retry: | |
1559 | ret = ipipe_prep(ipipe, flags); | |
1560 | if (ret) | |
1561 | return ret; | |
1562 | ||
1563 | ret = opipe_prep(opipe, flags); | |
1564 | if (ret) | |
1565 | return ret; | |
1566 | ||
1567 | /* | |
1568 | * Potential ABBA deadlock, work around it by ordering lock | |
1569 | * grabbing by pipe info address. Otherwise two different processes | |
1570 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1571 | */ | |
1572 | pipe_double_lock(ipipe, opipe); | |
1573 | ||
8cefc107 DH |
1574 | i_tail = ipipe->tail; |
1575 | i_mask = ipipe->ring_size - 1; | |
1576 | o_head = opipe->head; | |
1577 | o_mask = opipe->ring_size - 1; | |
1578 | ||
7c77f0b3 | 1579 | do { |
8cefc107 DH |
1580 | size_t o_len; |
1581 | ||
7c77f0b3 MS |
1582 | if (!opipe->readers) { |
1583 | send_sig(SIGPIPE, current, 0); | |
1584 | if (!ret) | |
1585 | ret = -EPIPE; | |
1586 | break; | |
1587 | } | |
1588 | ||
8cefc107 DH |
1589 | i_head = ipipe->head; |
1590 | o_tail = opipe->tail; | |
1591 | ||
1592 | if (pipe_empty(i_head, i_tail) && !ipipe->writers) | |
7c77f0b3 MS |
1593 | break; |
1594 | ||
1595 | /* | |
1596 | * Cannot make any progress, because either the input | |
1597 | * pipe is empty or the output pipe is full. | |
1598 | */ | |
8cefc107 | 1599 | if (pipe_empty(i_head, i_tail) || |
6718b6f8 | 1600 | pipe_full(o_head, o_tail, opipe->max_usage)) { |
7c77f0b3 MS |
1601 | /* Already processed some buffers, break */ |
1602 | if (ret) | |
1603 | break; | |
1604 | ||
1605 | if (flags & SPLICE_F_NONBLOCK) { | |
1606 | ret = -EAGAIN; | |
1607 | break; | |
1608 | } | |
1609 | ||
1610 | /* | |
1611 | * We raced with another reader/writer and haven't | |
1612 | * managed to process any buffers. A zero return | |
1613 | * value means EOF, so retry instead. | |
1614 | */ | |
1615 | pipe_unlock(ipipe); | |
1616 | pipe_unlock(opipe); | |
1617 | goto retry; | |
1618 | } | |
1619 | ||
8cefc107 DH |
1620 | ibuf = &ipipe->bufs[i_tail & i_mask]; |
1621 | obuf = &opipe->bufs[o_head & o_mask]; | |
7c77f0b3 MS |
1622 | |
1623 | if (len >= ibuf->len) { | |
1624 | /* | |
1625 | * Simply move the whole buffer from ipipe to opipe | |
1626 | */ | |
1627 | *obuf = *ibuf; | |
1628 | ibuf->ops = NULL; | |
8cefc107 DH |
1629 | i_tail++; |
1630 | ipipe->tail = i_tail; | |
7c77f0b3 | 1631 | input_wakeup = true; |
8cefc107 DH |
1632 | o_len = obuf->len; |
1633 | o_head++; | |
1634 | opipe->head = o_head; | |
7c77f0b3 MS |
1635 | } else { |
1636 | /* | |
1637 | * Get a reference to this pipe buffer, | |
1638 | * so we can copy the contents over. | |
1639 | */ | |
15fab63e MW |
1640 | if (!pipe_buf_get(ipipe, ibuf)) { |
1641 | if (ret == 0) | |
1642 | ret = -EFAULT; | |
1643 | break; | |
1644 | } | |
7c77f0b3 MS |
1645 | *obuf = *ibuf; |
1646 | ||
1647 | /* | |
f6dd9755 | 1648 | * Don't inherit the gift and merge flags, we need to |
7c77f0b3 MS |
1649 | * prevent multiple steals of this page. |
1650 | */ | |
1651 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
f6dd9755 | 1652 | obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
a0ce2f0a | 1653 | |
7c77f0b3 | 1654 | obuf->len = len; |
8cefc107 DH |
1655 | ibuf->offset += len; |
1656 | ibuf->len -= len; | |
1657 | o_len = len; | |
1658 | o_head++; | |
1659 | opipe->head = o_head; | |
7c77f0b3 | 1660 | } |
8cefc107 DH |
1661 | ret += o_len; |
1662 | len -= o_len; | |
7c77f0b3 MS |
1663 | } while (len); |
1664 | ||
1665 | pipe_unlock(ipipe); | |
1666 | pipe_unlock(opipe); | |
1667 | ||
1668 | /* | |
1669 | * If we put data in the output pipe, wakeup any potential readers. | |
1670 | */ | |
825cdcb1 NK |
1671 | if (ret > 0) |
1672 | wakeup_pipe_readers(opipe); | |
1673 | ||
7c77f0b3 MS |
1674 | if (input_wakeup) |
1675 | wakeup_pipe_writers(ipipe); | |
1676 | ||
1677 | return ret; | |
1678 | } | |
1679 | ||
70524490 JA |
1680 | /* |
1681 | * Link contents of ipipe to opipe. | |
1682 | */ | |
1683 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1684 | struct pipe_inode_info *opipe, | |
1685 | size_t len, unsigned int flags) | |
1686 | { | |
1687 | struct pipe_buffer *ibuf, *obuf; | |
8cefc107 DH |
1688 | unsigned int i_head, o_head; |
1689 | unsigned int i_tail, o_tail; | |
1690 | unsigned int i_mask, o_mask; | |
1691 | int ret = 0; | |
70524490 JA |
1692 | |
1693 | /* | |
1694 | * Potential ABBA deadlock, work around it by ordering lock | |
61e0d47c | 1695 | * grabbing by pipe info address. Otherwise two different processes |
70524490 JA |
1696 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1697 | */ | |
61e0d47c | 1698 | pipe_double_lock(ipipe, opipe); |
70524490 | 1699 | |
8cefc107 DH |
1700 | i_tail = ipipe->tail; |
1701 | i_mask = ipipe->ring_size - 1; | |
1702 | o_head = opipe->head; | |
1703 | o_mask = opipe->ring_size - 1; | |
1704 | ||
aadd06e5 | 1705 | do { |
70524490 JA |
1706 | if (!opipe->readers) { |
1707 | send_sig(SIGPIPE, current, 0); | |
1708 | if (!ret) | |
1709 | ret = -EPIPE; | |
1710 | break; | |
1711 | } | |
70524490 | 1712 | |
8cefc107 DH |
1713 | i_head = ipipe->head; |
1714 | o_tail = opipe->tail; | |
1715 | ||
aadd06e5 | 1716 | /* |
8cefc107 | 1717 | * If we have iterated all input buffers or run out of |
aadd06e5 JA |
1718 | * output room, break. |
1719 | */ | |
8cefc107 | 1720 | if (pipe_empty(i_head, i_tail) || |
6718b6f8 | 1721 | pipe_full(o_head, o_tail, opipe->max_usage)) |
aadd06e5 | 1722 | break; |
70524490 | 1723 | |
8cefc107 DH |
1724 | ibuf = &ipipe->bufs[i_tail & i_mask]; |
1725 | obuf = &opipe->bufs[o_head & o_mask]; | |
70524490 JA |
1726 | |
1727 | /* | |
aadd06e5 JA |
1728 | * Get a reference to this pipe buffer, |
1729 | * so we can copy the contents over. | |
70524490 | 1730 | */ |
15fab63e MW |
1731 | if (!pipe_buf_get(ipipe, ibuf)) { |
1732 | if (ret == 0) | |
1733 | ret = -EFAULT; | |
1734 | break; | |
1735 | } | |
aadd06e5 | 1736 | |
aadd06e5 JA |
1737 | *obuf = *ibuf; |
1738 | ||
2a27250e | 1739 | /* |
f6dd9755 CH |
1740 | * Don't inherit the gift and merge flag, we need to prevent |
1741 | * multiple steals of this page. | |
2a27250e | 1742 | */ |
aadd06e5 | 1743 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
f6dd9755 | 1744 | obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
a0ce2f0a | 1745 | |
aadd06e5 JA |
1746 | if (obuf->len > len) |
1747 | obuf->len = len; | |
aadd06e5 JA |
1748 | ret += obuf->len; |
1749 | len -= obuf->len; | |
8cefc107 DH |
1750 | |
1751 | o_head++; | |
1752 | opipe->head = o_head; | |
1753 | i_tail++; | |
aadd06e5 | 1754 | } while (len); |
70524490 | 1755 | |
61e0d47c MS |
1756 | pipe_unlock(ipipe); |
1757 | pipe_unlock(opipe); | |
70524490 | 1758 | |
aadd06e5 JA |
1759 | /* |
1760 | * If we put data in the output pipe, wakeup any potential readers. | |
1761 | */ | |
825cdcb1 NK |
1762 | if (ret > 0) |
1763 | wakeup_pipe_readers(opipe); | |
70524490 JA |
1764 | |
1765 | return ret; | |
1766 | } | |
1767 | ||
1768 | /* | |
1769 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1770 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1771 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1772 | * applicable one is SPLICE_F_NONBLOCK. | |
1773 | */ | |
9dafdfc2 | 1774 | long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags) |
70524490 | 1775 | { |
c73be61c DH |
1776 | struct pipe_inode_info *ipipe = get_pipe_info(in, true); |
1777 | struct pipe_inode_info *opipe = get_pipe_info(out, true); | |
aadd06e5 | 1778 | int ret = -EINVAL; |
70524490 | 1779 | |
90da2e3f PB |
1780 | if (unlikely(!(in->f_mode & FMODE_READ) || |
1781 | !(out->f_mode & FMODE_WRITE))) | |
1782 | return -EBADF; | |
1783 | ||
70524490 | 1784 | /* |
aadd06e5 JA |
1785 | * Duplicate the contents of ipipe to opipe without actually |
1786 | * copying the data. | |
70524490 | 1787 | */ |
aadd06e5 | 1788 | if (ipipe && opipe && ipipe != opipe) { |
ee5e0011 SK |
1789 | if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
1790 | flags |= SPLICE_F_NONBLOCK; | |
1791 | ||
aadd06e5 JA |
1792 | /* |
1793 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1794 | * ordering doesn't really matter. | |
1795 | */ | |
7c77f0b3 | 1796 | ret = ipipe_prep(ipipe, flags); |
aadd06e5 | 1797 | if (!ret) { |
7c77f0b3 | 1798 | ret = opipe_prep(opipe, flags); |
02cf01ae | 1799 | if (!ret) |
aadd06e5 | 1800 | ret = link_pipe(ipipe, opipe, len, flags); |
aadd06e5 JA |
1801 | } |
1802 | } | |
70524490 | 1803 | |
aadd06e5 | 1804 | return ret; |
70524490 JA |
1805 | } |
1806 | ||
836f92ad | 1807 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
70524490 | 1808 | { |
90da2e3f | 1809 | struct fd in, out; |
2903ff01 | 1810 | int error; |
70524490 | 1811 | |
3d6ea290 AV |
1812 | if (unlikely(flags & ~SPLICE_F_ALL)) |
1813 | return -EINVAL; | |
1814 | ||
70524490 JA |
1815 | if (unlikely(!len)) |
1816 | return 0; | |
1817 | ||
1818 | error = -EBADF; | |
2903ff01 AV |
1819 | in = fdget(fdin); |
1820 | if (in.file) { | |
90da2e3f PB |
1821 | out = fdget(fdout); |
1822 | if (out.file) { | |
1823 | error = do_tee(in.file, out.file, len, flags); | |
1824 | fdput(out); | |
70524490 | 1825 | } |
2903ff01 | 1826 | fdput(in); |
70524490 JA |
1827 | } |
1828 | ||
1829 | return error; | |
1830 | } |