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Commit | Line | Data |
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5274f052 JA |
1 | /* |
2 | * "splice": joining two ropes together by interweaving their strands. | |
3 | * | |
4 | * This is the "extended pipe" functionality, where a pipe is used as | |
5 | * an arbitrary in-memory buffer. Think of a pipe as a small kernel | |
6 | * buffer that you can use to transfer data from one end to the other. | |
7 | * | |
8 | * The traditional unix read/write is extended with a "splice()" operation | |
9 | * that transfers data buffers to or from a pipe buffer. | |
10 | * | |
11 | * Named by Larry McVoy, original implementation from Linus, extended by | |
c2058e06 JA |
12 | * Jens to support splicing to files, network, direct splicing, etc and |
13 | * fixing lots of bugs. | |
5274f052 | 14 | * |
0fe23479 | 15 | * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
c2058e06 JA |
16 | * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
17 | * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> | |
5274f052 JA |
18 | * |
19 | */ | |
20 | #include <linux/fs.h> | |
21 | #include <linux/file.h> | |
22 | #include <linux/pagemap.h> | |
d6b29d7c | 23 | #include <linux/splice.h> |
08e552c6 | 24 | #include <linux/memcontrol.h> |
5274f052 | 25 | #include <linux/mm_inline.h> |
5abc97aa | 26 | #include <linux/swap.h> |
4f6f0bd2 | 27 | #include <linux/writeback.h> |
630d9c47 | 28 | #include <linux/export.h> |
4f6f0bd2 | 29 | #include <linux/syscalls.h> |
912d35f8 | 30 | #include <linux/uio.h> |
29ce2058 | 31 | #include <linux/security.h> |
5a0e3ad6 | 32 | #include <linux/gfp.h> |
35f9c09f | 33 | #include <linux/socket.h> |
76b021d0 | 34 | #include <linux/compat.h> |
06ae43f3 | 35 | #include "internal.h" |
5274f052 | 36 | |
83f9135b JA |
37 | /* |
38 | * Attempt to steal a page from a pipe buffer. This should perhaps go into | |
39 | * a vm helper function, it's already simplified quite a bit by the | |
40 | * addition of remove_mapping(). If success is returned, the caller may | |
41 | * attempt to reuse this page for another destination. | |
42 | */ | |
76ad4d11 | 43 | static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
5abc97aa JA |
44 | struct pipe_buffer *buf) |
45 | { | |
46 | struct page *page = buf->page; | |
9e94cd4f | 47 | struct address_space *mapping; |
5abc97aa | 48 | |
9e0267c2 JA |
49 | lock_page(page); |
50 | ||
9e94cd4f JA |
51 | mapping = page_mapping(page); |
52 | if (mapping) { | |
53 | WARN_ON(!PageUptodate(page)); | |
5abc97aa | 54 | |
9e94cd4f JA |
55 | /* |
56 | * At least for ext2 with nobh option, we need to wait on | |
57 | * writeback completing on this page, since we'll remove it | |
58 | * from the pagecache. Otherwise truncate wont wait on the | |
59 | * page, allowing the disk blocks to be reused by someone else | |
60 | * before we actually wrote our data to them. fs corruption | |
61 | * ensues. | |
62 | */ | |
63 | wait_on_page_writeback(page); | |
ad8d6f0a | 64 | |
266cf658 DH |
65 | if (page_has_private(page) && |
66 | !try_to_release_page(page, GFP_KERNEL)) | |
ca39d651 | 67 | goto out_unlock; |
4f6f0bd2 | 68 | |
9e94cd4f JA |
69 | /* |
70 | * If we succeeded in removing the mapping, set LRU flag | |
71 | * and return good. | |
72 | */ | |
73 | if (remove_mapping(mapping, page)) { | |
74 | buf->flags |= PIPE_BUF_FLAG_LRU; | |
75 | return 0; | |
76 | } | |
9e0267c2 | 77 | } |
5abc97aa | 78 | |
9e94cd4f JA |
79 | /* |
80 | * Raced with truncate or failed to remove page from current | |
81 | * address space, unlock and return failure. | |
82 | */ | |
ca39d651 | 83 | out_unlock: |
9e94cd4f JA |
84 | unlock_page(page); |
85 | return 1; | |
5abc97aa JA |
86 | } |
87 | ||
76ad4d11 | 88 | static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
5274f052 JA |
89 | struct pipe_buffer *buf) |
90 | { | |
09cbfeaf | 91 | put_page(buf->page); |
1432873a | 92 | buf->flags &= ~PIPE_BUF_FLAG_LRU; |
5274f052 JA |
93 | } |
94 | ||
0845718d JA |
95 | /* |
96 | * Check whether the contents of buf is OK to access. Since the content | |
97 | * is a page cache page, IO may be in flight. | |
98 | */ | |
cac36bb0 JA |
99 | static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
100 | struct pipe_buffer *buf) | |
5274f052 JA |
101 | { |
102 | struct page *page = buf->page; | |
49d0b21b | 103 | int err; |
5274f052 JA |
104 | |
105 | if (!PageUptodate(page)) { | |
49d0b21b JA |
106 | lock_page(page); |
107 | ||
108 | /* | |
109 | * Page got truncated/unhashed. This will cause a 0-byte | |
73d62d83 | 110 | * splice, if this is the first page. |
49d0b21b JA |
111 | */ |
112 | if (!page->mapping) { | |
113 | err = -ENODATA; | |
114 | goto error; | |
115 | } | |
5274f052 | 116 | |
49d0b21b | 117 | /* |
73d62d83 | 118 | * Uh oh, read-error from disk. |
49d0b21b JA |
119 | */ |
120 | if (!PageUptodate(page)) { | |
121 | err = -EIO; | |
122 | goto error; | |
123 | } | |
124 | ||
125 | /* | |
f84d7519 | 126 | * Page is ok afterall, we are done. |
49d0b21b | 127 | */ |
5274f052 | 128 | unlock_page(page); |
5274f052 JA |
129 | } |
130 | ||
f84d7519 | 131 | return 0; |
49d0b21b JA |
132 | error: |
133 | unlock_page(page); | |
f84d7519 | 134 | return err; |
70524490 JA |
135 | } |
136 | ||
708e3508 | 137 | const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
5274f052 | 138 | .can_merge = 0, |
cac36bb0 | 139 | .confirm = page_cache_pipe_buf_confirm, |
5274f052 | 140 | .release = page_cache_pipe_buf_release, |
5abc97aa | 141 | .steal = page_cache_pipe_buf_steal, |
f84d7519 | 142 | .get = generic_pipe_buf_get, |
5274f052 JA |
143 | }; |
144 | ||
912d35f8 JA |
145 | static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
146 | struct pipe_buffer *buf) | |
147 | { | |
7afa6fd0 JA |
148 | if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
149 | return 1; | |
150 | ||
1432873a | 151 | buf->flags |= PIPE_BUF_FLAG_LRU; |
330ab716 | 152 | return generic_pipe_buf_steal(pipe, buf); |
912d35f8 JA |
153 | } |
154 | ||
d4c3cca9 | 155 | static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
912d35f8 | 156 | .can_merge = 0, |
cac36bb0 | 157 | .confirm = generic_pipe_buf_confirm, |
912d35f8 JA |
158 | .release = page_cache_pipe_buf_release, |
159 | .steal = user_page_pipe_buf_steal, | |
f84d7519 | 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(); | |
166 | if (waitqueue_active(&pipe->wait)) | |
167 | wake_up_interruptible(&pipe->wait); | |
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; |
8924feff | 186 | int ret = 0, page_nr = 0; |
5274f052 | 187 | |
d6785d91 RV |
188 | if (!spd_pages) |
189 | return 0; | |
190 | ||
8924feff AV |
191 | if (unlikely(!pipe->readers)) { |
192 | send_sig(SIGPIPE, current, 0); | |
193 | ret = -EPIPE; | |
194 | goto out; | |
195 | } | |
5274f052 | 196 | |
8924feff AV |
197 | while (pipe->nrbufs < pipe->buffers) { |
198 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
199 | struct pipe_buffer *buf = pipe->bufs + newbuf; | |
5274f052 | 200 | |
8924feff AV |
201 | buf->page = spd->pages[page_nr]; |
202 | buf->offset = spd->partial[page_nr].offset; | |
203 | buf->len = spd->partial[page_nr].len; | |
204 | buf->private = spd->partial[page_nr].private; | |
205 | buf->ops = spd->ops; | |
5274f052 | 206 | |
8924feff AV |
207 | pipe->nrbufs++; |
208 | page_nr++; | |
209 | ret += buf->len; | |
29e35094 | 210 | |
8924feff | 211 | if (!--spd->nr_pages) |
5274f052 | 212 | break; |
5274f052 JA |
213 | } |
214 | ||
8924feff AV |
215 | if (!ret) |
216 | ret = -EAGAIN; | |
5274f052 | 217 | |
8924feff | 218 | out: |
00de00bd | 219 | while (page_nr < spd_pages) |
bbdfc2f7 | 220 | spd->spd_release(spd, page_nr++); |
5274f052 JA |
221 | |
222 | return ret; | |
223 | } | |
2b514574 | 224 | EXPORT_SYMBOL_GPL(splice_to_pipe); |
5274f052 | 225 | |
79fddc4e AV |
226 | ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
227 | { | |
228 | int ret; | |
229 | ||
230 | if (unlikely(!pipe->readers)) { | |
231 | send_sig(SIGPIPE, current, 0); | |
232 | ret = -EPIPE; | |
233 | } else if (pipe->nrbufs == pipe->buffers) { | |
234 | ret = -EAGAIN; | |
235 | } else { | |
236 | int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1); | |
237 | pipe->bufs[newbuf] = *buf; | |
238 | pipe->nrbufs++; | |
239 | return buf->len; | |
240 | } | |
a779638c | 241 | pipe_buf_release(pipe, buf); |
79fddc4e AV |
242 | return ret; |
243 | } | |
244 | EXPORT_SYMBOL(add_to_pipe); | |
245 | ||
708e3508 | 246 | void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
bbdfc2f7 | 247 | { |
09cbfeaf | 248 | put_page(spd->pages[i]); |
bbdfc2f7 JA |
249 | } |
250 | ||
35f3d14d JA |
251 | /* |
252 | * Check if we need to grow the arrays holding pages and partial page | |
253 | * descriptions. | |
254 | */ | |
047fe360 | 255 | int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
35f3d14d | 256 | { |
047fe360 ED |
257 | unsigned int buffers = ACCESS_ONCE(pipe->buffers); |
258 | ||
259 | spd->nr_pages_max = buffers; | |
260 | if (buffers <= PIPE_DEF_BUFFERS) | |
35f3d14d JA |
261 | return 0; |
262 | ||
047fe360 ED |
263 | spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL); |
264 | spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL); | |
35f3d14d JA |
265 | |
266 | if (spd->pages && spd->partial) | |
267 | return 0; | |
268 | ||
269 | kfree(spd->pages); | |
270 | kfree(spd->partial); | |
271 | return -ENOMEM; | |
272 | } | |
273 | ||
047fe360 | 274 | void splice_shrink_spd(struct splice_pipe_desc *spd) |
35f3d14d | 275 | { |
047fe360 | 276 | if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
35f3d14d JA |
277 | return; |
278 | ||
279 | kfree(spd->pages); | |
280 | kfree(spd->partial); | |
281 | } | |
282 | ||
83f9135b JA |
283 | /** |
284 | * generic_file_splice_read - splice data from file to a pipe | |
285 | * @in: file to splice from | |
932cc6d4 | 286 | * @ppos: position in @in |
83f9135b JA |
287 | * @pipe: pipe to splice to |
288 | * @len: number of bytes to splice | |
289 | * @flags: splice modifier flags | |
290 | * | |
932cc6d4 JA |
291 | * Description: |
292 | * Will read pages from given file and fill them into a pipe. Can be | |
82c156f8 | 293 | * used as long as it has more or less sane ->read_iter(). |
932cc6d4 | 294 | * |
83f9135b | 295 | */ |
cbb7e577 JA |
296 | ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
297 | struct pipe_inode_info *pipe, size_t len, | |
298 | unsigned int flags) | |
5274f052 | 299 | { |
82c156f8 AV |
300 | struct iov_iter to; |
301 | struct kiocb kiocb; | |
82c156f8 | 302 | int idx, ret; |
be64f884 | 303 | |
82c156f8 AV |
304 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len); |
305 | idx = to.idx; | |
306 | init_sync_kiocb(&kiocb, in); | |
307 | kiocb.ki_pos = *ppos; | |
308 | ret = in->f_op->read_iter(&kiocb, &to); | |
723590ed | 309 | if (ret > 0) { |
82c156f8 | 310 | *ppos = kiocb.ki_pos; |
723590ed | 311 | file_accessed(in); |
82c156f8 | 312 | } else if (ret < 0) { |
c3a69024 AV |
313 | to.idx = idx; |
314 | to.iov_offset = 0; | |
315 | iov_iter_advance(&to, 0); /* to free what was emitted */ | |
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 = { |
6818173b | 329 | .can_merge = 0, |
6818173b MS |
330 | .confirm = generic_pipe_buf_confirm, |
331 | .release = generic_pipe_buf_release, | |
332 | .steal = generic_pipe_buf_steal, | |
333 | .get = generic_pipe_buf_get, | |
334 | }; | |
335 | ||
28a625cb MS |
336 | static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe, |
337 | struct pipe_buffer *buf) | |
338 | { | |
339 | return 1; | |
340 | } | |
341 | ||
342 | /* Pipe buffer operations for a socket and similar. */ | |
343 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { | |
344 | .can_merge = 0, | |
28a625cb MS |
345 | .confirm = generic_pipe_buf_confirm, |
346 | .release = generic_pipe_buf_release, | |
347 | .steal = generic_pipe_buf_nosteal, | |
348 | .get = generic_pipe_buf_get, | |
349 | }; | |
350 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); | |
351 | ||
523ac9af | 352 | static ssize_t kernel_readv(struct file *file, const struct kvec *vec, |
6818173b MS |
353 | unsigned long vlen, loff_t offset) |
354 | { | |
355 | mm_segment_t old_fs; | |
356 | loff_t pos = offset; | |
357 | ssize_t res; | |
358 | ||
359 | old_fs = get_fs(); | |
360 | set_fs(get_ds()); | |
361 | /* The cast to a user pointer is valid due to the set_fs() */ | |
793b80ef | 362 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0); |
6818173b MS |
363 | set_fs(old_fs); |
364 | ||
365 | return res; | |
366 | } | |
367 | ||
7bb307e8 | 368 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
b2858d7d | 369 | loff_t pos) |
0b0a47f5 MS |
370 | { |
371 | mm_segment_t old_fs; | |
372 | ssize_t res; | |
373 | ||
374 | old_fs = get_fs(); | |
375 | set_fs(get_ds()); | |
376 | /* The cast to a user pointer is valid due to the set_fs() */ | |
7bb307e8 | 377 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); |
0b0a47f5 MS |
378 | set_fs(old_fs); |
379 | ||
380 | return res; | |
381 | } | |
7bb307e8 | 382 | EXPORT_SYMBOL(kernel_write); |
0b0a47f5 | 383 | |
82c156f8 | 384 | static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
6818173b MS |
385 | struct pipe_inode_info *pipe, size_t len, |
386 | unsigned int flags) | |
387 | { | |
523ac9af AV |
388 | struct kvec *vec, __vec[PIPE_DEF_BUFFERS]; |
389 | struct iov_iter to; | |
390 | struct page **pages; | |
6818173b | 391 | unsigned int nr_pages; |
523ac9af | 392 | size_t offset, dummy, copied = 0; |
6818173b | 393 | ssize_t res; |
6818173b | 394 | int i; |
35f3d14d | 395 | |
523ac9af AV |
396 | if (pipe->nrbufs == pipe->buffers) |
397 | return -EAGAIN; | |
35f3d14d | 398 | |
523ac9af AV |
399 | /* |
400 | * Try to keep page boundaries matching to source pagecache ones - | |
401 | * it probably won't be much help, but... | |
402 | */ | |
09cbfeaf | 403 | offset = *ppos & ~PAGE_MASK; |
6818173b | 404 | |
523ac9af | 405 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset); |
6818173b | 406 | |
523ac9af AV |
407 | res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &dummy); |
408 | if (res <= 0) | |
409 | return -ENOMEM; | |
6818173b | 410 | |
523ac9af | 411 | nr_pages = res / PAGE_SIZE; |
6818173b | 412 | |
523ac9af AV |
413 | vec = __vec; |
414 | if (nr_pages > PIPE_DEF_BUFFERS) { | |
415 | vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL); | |
416 | if (unlikely(!vec)) { | |
417 | res = -ENOMEM; | |
418 | goto out; | |
419 | } | |
77f6bf57 | 420 | } |
6818173b | 421 | |
523ac9af AV |
422 | pipe->bufs[to.idx].offset = offset; |
423 | pipe->bufs[to.idx].len -= offset; | |
424 | ||
425 | for (i = 0; i < nr_pages; i++) { | |
426 | size_t this_len = min_t(size_t, len, PAGE_SIZE - offset); | |
427 | vec[i].iov_base = page_address(pages[i]) + offset; | |
428 | vec[i].iov_len = this_len; | |
429 | len -= this_len; | |
430 | offset = 0; | |
6818173b | 431 | } |
6818173b | 432 | |
523ac9af AV |
433 | res = kernel_readv(in, vec, nr_pages, *ppos); |
434 | if (res > 0) { | |
435 | copied = res; | |
6818173b | 436 | *ppos += res; |
523ac9af | 437 | } |
6818173b | 438 | |
35f3d14d JA |
439 | if (vec != __vec) |
440 | kfree(vec); | |
523ac9af AV |
441 | out: |
442 | for (i = 0; i < nr_pages; i++) | |
443 | put_page(pages[i]); | |
444 | kvfree(pages); | |
445 | iov_iter_advance(&to, copied); /* truncates and discards */ | |
6818173b | 446 | return res; |
6818173b | 447 | } |
6818173b | 448 | |
5274f052 | 449 | /* |
4f6f0bd2 | 450 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 451 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 452 | */ |
76ad4d11 | 453 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
454 | struct pipe_buffer *buf, struct splice_desc *sd) |
455 | { | |
6a14b90b | 456 | struct file *file = sd->u.file; |
5274f052 | 457 | loff_t pos = sd->pos; |
a8adbe37 | 458 | int more; |
5274f052 | 459 | |
72c2d531 | 460 | if (!likely(file->f_op->sendpage)) |
a8adbe37 MM |
461 | return -EINVAL; |
462 | ||
35f9c09f | 463 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
ae62ca7b ED |
464 | |
465 | if (sd->len < sd->total_len && pipe->nrbufs > 1) | |
35f9c09f | 466 | more |= MSG_SENDPAGE_NOTLAST; |
ae62ca7b | 467 | |
a8adbe37 MM |
468 | return file->f_op->sendpage(file, buf->page, buf->offset, |
469 | sd->len, &pos, more); | |
5274f052 JA |
470 | } |
471 | ||
b3c2d2dd MS |
472 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
473 | { | |
474 | smp_mb(); | |
475 | if (waitqueue_active(&pipe->wait)) | |
476 | wake_up_interruptible(&pipe->wait); | |
477 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
478 | } | |
479 | ||
932cc6d4 | 480 | /** |
b3c2d2dd | 481 | * splice_from_pipe_feed - feed available data from a pipe to a file |
932cc6d4 JA |
482 | * @pipe: pipe to splice from |
483 | * @sd: information to @actor | |
484 | * @actor: handler that splices the data | |
485 | * | |
486 | * Description: | |
b3c2d2dd MS |
487 | * This function loops over the pipe and calls @actor to do the |
488 | * actual moving of a single struct pipe_buffer to the desired | |
489 | * destination. It returns when there's no more buffers left in | |
490 | * the pipe or if the requested number of bytes (@sd->total_len) | |
491 | * have been copied. It returns a positive number (one) if the | |
492 | * pipe needs to be filled with more data, zero if the required | |
493 | * number of bytes have been copied and -errno on error. | |
932cc6d4 | 494 | * |
b3c2d2dd MS |
495 | * This, together with splice_from_pipe_{begin,end,next}, may be |
496 | * used to implement the functionality of __splice_from_pipe() when | |
497 | * locking is required around copying the pipe buffers to the | |
498 | * destination. | |
83f9135b | 499 | */ |
96f9bc8f | 500 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
b3c2d2dd | 501 | splice_actor *actor) |
5274f052 | 502 | { |
b3c2d2dd | 503 | int ret; |
5274f052 | 504 | |
b3c2d2dd MS |
505 | while (pipe->nrbufs) { |
506 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
5274f052 | 507 | |
b3c2d2dd MS |
508 | sd->len = buf->len; |
509 | if (sd->len > sd->total_len) | |
510 | sd->len = sd->total_len; | |
5274f052 | 511 | |
fba597db | 512 | ret = pipe_buf_confirm(pipe, buf); |
a8adbe37 | 513 | if (unlikely(ret)) { |
b3c2d2dd MS |
514 | if (ret == -ENODATA) |
515 | ret = 0; | |
516 | return ret; | |
517 | } | |
a8adbe37 MM |
518 | |
519 | ret = actor(pipe, buf, sd); | |
520 | if (ret <= 0) | |
521 | return ret; | |
522 | ||
b3c2d2dd MS |
523 | buf->offset += ret; |
524 | buf->len -= ret; | |
525 | ||
526 | sd->num_spliced += ret; | |
527 | sd->len -= ret; | |
528 | sd->pos += ret; | |
529 | sd->total_len -= ret; | |
530 | ||
531 | if (!buf->len) { | |
a779638c | 532 | pipe_buf_release(pipe, buf); |
35f3d14d | 533 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
b3c2d2dd | 534 | pipe->nrbufs--; |
6447a3cf | 535 | if (pipe->files) |
b3c2d2dd MS |
536 | sd->need_wakeup = true; |
537 | } | |
5274f052 | 538 | |
b3c2d2dd MS |
539 | if (!sd->total_len) |
540 | return 0; | |
541 | } | |
5274f052 | 542 | |
b3c2d2dd MS |
543 | return 1; |
544 | } | |
5274f052 | 545 | |
b3c2d2dd MS |
546 | /** |
547 | * splice_from_pipe_next - wait for some data to splice from | |
548 | * @pipe: pipe to splice from | |
549 | * @sd: information about the splice operation | |
550 | * | |
551 | * Description: | |
552 | * This function will wait for some data and return a positive | |
553 | * value (one) if pipe buffers are available. It will return zero | |
554 | * or -errno if no more data needs to be spliced. | |
555 | */ | |
96f9bc8f | 556 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd | 557 | { |
c725bfce JK |
558 | /* |
559 | * Check for signal early to make process killable when there are | |
560 | * always buffers available | |
561 | */ | |
562 | if (signal_pending(current)) | |
563 | return -ERESTARTSYS; | |
564 | ||
b3c2d2dd MS |
565 | while (!pipe->nrbufs) { |
566 | if (!pipe->writers) | |
567 | return 0; | |
016b661e | 568 | |
b3c2d2dd MS |
569 | if (!pipe->waiting_writers && sd->num_spliced) |
570 | return 0; | |
73d62d83 | 571 | |
b3c2d2dd MS |
572 | if (sd->flags & SPLICE_F_NONBLOCK) |
573 | return -EAGAIN; | |
5274f052 | 574 | |
b3c2d2dd MS |
575 | if (signal_pending(current)) |
576 | return -ERESTARTSYS; | |
5274f052 | 577 | |
b3c2d2dd MS |
578 | if (sd->need_wakeup) { |
579 | wakeup_pipe_writers(pipe); | |
580 | sd->need_wakeup = false; | |
5274f052 JA |
581 | } |
582 | ||
b3c2d2dd MS |
583 | pipe_wait(pipe); |
584 | } | |
29e35094 | 585 | |
b3c2d2dd MS |
586 | return 1; |
587 | } | |
5274f052 | 588 | |
b3c2d2dd MS |
589 | /** |
590 | * splice_from_pipe_begin - start splicing from pipe | |
b80901bb | 591 | * @sd: information about the splice operation |
b3c2d2dd MS |
592 | * |
593 | * Description: | |
594 | * This function should be called before a loop containing | |
595 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
596 | * initialize the necessary fields of @sd. | |
597 | */ | |
96f9bc8f | 598 | static void splice_from_pipe_begin(struct splice_desc *sd) |
b3c2d2dd MS |
599 | { |
600 | sd->num_spliced = 0; | |
601 | sd->need_wakeup = false; | |
602 | } | |
5274f052 | 603 | |
b3c2d2dd MS |
604 | /** |
605 | * splice_from_pipe_end - finish splicing from pipe | |
606 | * @pipe: pipe to splice from | |
607 | * @sd: information about the splice operation | |
608 | * | |
609 | * Description: | |
610 | * This function will wake up pipe writers if necessary. It should | |
611 | * be called after a loop containing splice_from_pipe_next() and | |
612 | * splice_from_pipe_feed(). | |
613 | */ | |
96f9bc8f | 614 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd MS |
615 | { |
616 | if (sd->need_wakeup) | |
617 | wakeup_pipe_writers(pipe); | |
618 | } | |
5274f052 | 619 | |
b3c2d2dd MS |
620 | /** |
621 | * __splice_from_pipe - splice data from a pipe to given actor | |
622 | * @pipe: pipe to splice from | |
623 | * @sd: information to @actor | |
624 | * @actor: handler that splices the data | |
625 | * | |
626 | * Description: | |
627 | * This function does little more than loop over the pipe and call | |
628 | * @actor to do the actual moving of a single struct pipe_buffer to | |
629 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
630 | * pipe_to_user. | |
631 | * | |
632 | */ | |
633 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
634 | splice_actor *actor) | |
635 | { | |
636 | int ret; | |
5274f052 | 637 | |
b3c2d2dd MS |
638 | splice_from_pipe_begin(sd); |
639 | do { | |
c2489e07 | 640 | cond_resched(); |
b3c2d2dd MS |
641 | ret = splice_from_pipe_next(pipe, sd); |
642 | if (ret > 0) | |
643 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
644 | } while (ret > 0); | |
645 | splice_from_pipe_end(pipe, sd); | |
646 | ||
647 | return sd->num_spliced ? sd->num_spliced : ret; | |
5274f052 | 648 | } |
40bee44e | 649 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 650 | |
932cc6d4 JA |
651 | /** |
652 | * splice_from_pipe - splice data from a pipe to a file | |
653 | * @pipe: pipe to splice from | |
654 | * @out: file to splice to | |
655 | * @ppos: position in @out | |
656 | * @len: how many bytes to splice | |
657 | * @flags: splice modifier flags | |
658 | * @actor: handler that splices the data | |
659 | * | |
660 | * Description: | |
2933970b | 661 | * See __splice_from_pipe. This function locks the pipe inode, |
932cc6d4 JA |
662 | * otherwise it's identical to __splice_from_pipe(). |
663 | * | |
664 | */ | |
6da61809 MF |
665 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
666 | loff_t *ppos, size_t len, unsigned int flags, | |
667 | splice_actor *actor) | |
668 | { | |
669 | ssize_t ret; | |
c66ab6fa JA |
670 | struct splice_desc sd = { |
671 | .total_len = len, | |
672 | .flags = flags, | |
673 | .pos = *ppos, | |
6a14b90b | 674 | .u.file = out, |
c66ab6fa | 675 | }; |
6da61809 | 676 | |
61e0d47c | 677 | pipe_lock(pipe); |
c66ab6fa | 678 | ret = __splice_from_pipe(pipe, &sd, actor); |
61e0d47c | 679 | pipe_unlock(pipe); |
6da61809 MF |
680 | |
681 | return ret; | |
682 | } | |
683 | ||
8d020765 AV |
684 | /** |
685 | * iter_file_splice_write - splice data from a pipe to a file | |
686 | * @pipe: pipe info | |
687 | * @out: file to write to | |
688 | * @ppos: position in @out | |
689 | * @len: number of bytes to splice | |
690 | * @flags: splice modifier flags | |
691 | * | |
692 | * Description: | |
693 | * Will either move or copy pages (determined by @flags options) from | |
694 | * the given pipe inode to the given file. | |
695 | * This one is ->write_iter-based. | |
696 | * | |
697 | */ | |
698 | ssize_t | |
699 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
700 | loff_t *ppos, size_t len, unsigned int flags) | |
701 | { | |
702 | struct splice_desc sd = { | |
703 | .total_len = len, | |
704 | .flags = flags, | |
705 | .pos = *ppos, | |
706 | .u.file = out, | |
707 | }; | |
708 | int nbufs = pipe->buffers; | |
709 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), | |
710 | GFP_KERNEL); | |
711 | ssize_t ret; | |
712 | ||
713 | if (unlikely(!array)) | |
714 | return -ENOMEM; | |
715 | ||
716 | pipe_lock(pipe); | |
717 | ||
718 | splice_from_pipe_begin(&sd); | |
719 | while (sd.total_len) { | |
720 | struct iov_iter from; | |
8d020765 AV |
721 | size_t left; |
722 | int n, idx; | |
723 | ||
724 | ret = splice_from_pipe_next(pipe, &sd); | |
725 | if (ret <= 0) | |
726 | break; | |
727 | ||
728 | if (unlikely(nbufs < pipe->buffers)) { | |
729 | kfree(array); | |
730 | nbufs = pipe->buffers; | |
731 | array = kcalloc(nbufs, sizeof(struct bio_vec), | |
732 | GFP_KERNEL); | |
733 | if (!array) { | |
734 | ret = -ENOMEM; | |
735 | break; | |
736 | } | |
737 | } | |
738 | ||
739 | /* build the vector */ | |
740 | left = sd.total_len; | |
741 | for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) { | |
742 | struct pipe_buffer *buf = pipe->bufs + idx; | |
743 | size_t this_len = buf->len; | |
744 | ||
745 | if (this_len > left) | |
746 | this_len = left; | |
747 | ||
748 | if (idx == pipe->buffers - 1) | |
749 | idx = -1; | |
750 | ||
fba597db | 751 | ret = pipe_buf_confirm(pipe, buf); |
8d020765 AV |
752 | if (unlikely(ret)) { |
753 | if (ret == -ENODATA) | |
754 | ret = 0; | |
755 | goto done; | |
756 | } | |
757 | ||
758 | array[n].bv_page = buf->page; | |
759 | array[n].bv_len = this_len; | |
760 | array[n].bv_offset = buf->offset; | |
761 | left -= this_len; | |
762 | } | |
763 | ||
05afcb77 AV |
764 | iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n, |
765 | sd.total_len - left); | |
dbe4e192 | 766 | ret = vfs_iter_write(out, &from, &sd.pos); |
8d020765 AV |
767 | if (ret <= 0) |
768 | break; | |
769 | ||
770 | sd.num_spliced += ret; | |
771 | sd.total_len -= ret; | |
dbe4e192 | 772 | *ppos = sd.pos; |
8d020765 AV |
773 | |
774 | /* dismiss the fully eaten buffers, adjust the partial one */ | |
775 | while (ret) { | |
776 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
777 | if (ret >= buf->len) { | |
8d020765 AV |
778 | ret -= buf->len; |
779 | buf->len = 0; | |
a779638c | 780 | pipe_buf_release(pipe, buf); |
8d020765 AV |
781 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
782 | pipe->nrbufs--; | |
783 | if (pipe->files) | |
784 | sd.need_wakeup = true; | |
785 | } else { | |
786 | buf->offset += ret; | |
787 | buf->len -= ret; | |
788 | ret = 0; | |
789 | } | |
790 | } | |
791 | } | |
792 | done: | |
793 | kfree(array); | |
794 | splice_from_pipe_end(pipe, &sd); | |
795 | ||
796 | pipe_unlock(pipe); | |
797 | ||
798 | if (sd.num_spliced) | |
799 | ret = sd.num_spliced; | |
800 | ||
801 | return ret; | |
802 | } | |
803 | ||
804 | EXPORT_SYMBOL(iter_file_splice_write); | |
805 | ||
b2858d7d MS |
806 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
807 | struct splice_desc *sd) | |
0b0a47f5 | 808 | { |
b2858d7d MS |
809 | int ret; |
810 | void *data; | |
06ae43f3 | 811 | loff_t tmp = sd->pos; |
b2858d7d | 812 | |
fbb32750 | 813 | data = kmap(buf->page); |
06ae43f3 | 814 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); |
fbb32750 | 815 | kunmap(buf->page); |
b2858d7d MS |
816 | |
817 | return ret; | |
0b0a47f5 MS |
818 | } |
819 | ||
820 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, | |
821 | struct file *out, loff_t *ppos, | |
822 | size_t len, unsigned int flags) | |
823 | { | |
b2858d7d | 824 | ssize_t ret; |
0b0a47f5 | 825 | |
b2858d7d MS |
826 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
827 | if (ret > 0) | |
828 | *ppos += ret; | |
0b0a47f5 | 829 | |
b2858d7d | 830 | return ret; |
0b0a47f5 MS |
831 | } |
832 | ||
83f9135b JA |
833 | /** |
834 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 835 | * @pipe: pipe to splice from |
83f9135b | 836 | * @out: socket to write to |
932cc6d4 | 837 | * @ppos: position in @out |
83f9135b JA |
838 | * @len: number of bytes to splice |
839 | * @flags: splice modifier flags | |
840 | * | |
932cc6d4 JA |
841 | * Description: |
842 | * Will send @len bytes from the pipe to a network socket. No data copying | |
843 | * is involved. | |
83f9135b JA |
844 | * |
845 | */ | |
3a326a2c | 846 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 847 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 848 | { |
00522fb4 | 849 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
850 | } |
851 | ||
059a8f37 | 852 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 853 | |
83f9135b JA |
854 | /* |
855 | * Attempt to initiate a splice from pipe to file. | |
856 | */ | |
3a326a2c | 857 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 858 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 859 | { |
0b0a47f5 MS |
860 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
861 | loff_t *, size_t, unsigned int); | |
5274f052 | 862 | |
72c2d531 | 863 | if (out->f_op->splice_write) |
cc56f7de CG |
864 | splice_write = out->f_op->splice_write; |
865 | else | |
0b0a47f5 MS |
866 | splice_write = default_file_splice_write; |
867 | ||
500368f7 | 868 | return splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
869 | } |
870 | ||
83f9135b JA |
871 | /* |
872 | * Attempt to initiate a splice from a file to a pipe. | |
873 | */ | |
cbb7e577 JA |
874 | static long do_splice_to(struct file *in, loff_t *ppos, |
875 | struct pipe_inode_info *pipe, size_t len, | |
876 | unsigned int flags) | |
5274f052 | 877 | { |
6818173b MS |
878 | ssize_t (*splice_read)(struct file *, loff_t *, |
879 | struct pipe_inode_info *, size_t, unsigned int); | |
5274f052 JA |
880 | int ret; |
881 | ||
49570e9b | 882 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
883 | return -EBADF; |
884 | ||
cbb7e577 | 885 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
886 | if (unlikely(ret < 0)) |
887 | return ret; | |
888 | ||
03cc0789 AV |
889 | if (unlikely(len > MAX_RW_COUNT)) |
890 | len = MAX_RW_COUNT; | |
891 | ||
72c2d531 | 892 | if (in->f_op->splice_read) |
cc56f7de CG |
893 | splice_read = in->f_op->splice_read; |
894 | else | |
6818173b MS |
895 | splice_read = default_file_splice_read; |
896 | ||
897 | return splice_read(in, ppos, pipe, len, flags); | |
5274f052 JA |
898 | } |
899 | ||
932cc6d4 JA |
900 | /** |
901 | * splice_direct_to_actor - splices data directly between two non-pipes | |
902 | * @in: file to splice from | |
903 | * @sd: actor information on where to splice to | |
904 | * @actor: handles the data splicing | |
905 | * | |
906 | * Description: | |
907 | * This is a special case helper to splice directly between two | |
908 | * points, without requiring an explicit pipe. Internally an allocated | |
79685b8d | 909 | * pipe is cached in the process, and reused during the lifetime of |
932cc6d4 JA |
910 | * that process. |
911 | * | |
c66ab6fa JA |
912 | */ |
913 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
914 | splice_direct_actor *actor) | |
b92ce558 JA |
915 | { |
916 | struct pipe_inode_info *pipe; | |
917 | long ret, bytes; | |
918 | umode_t i_mode; | |
c66ab6fa | 919 | size_t len; |
0ff28d9f | 920 | int i, flags, more; |
b92ce558 JA |
921 | |
922 | /* | |
923 | * We require the input being a regular file, as we don't want to | |
924 | * randomly drop data for eg socket -> socket splicing. Use the | |
925 | * piped splicing for that! | |
926 | */ | |
496ad9aa | 927 | i_mode = file_inode(in)->i_mode; |
b92ce558 JA |
928 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
929 | return -EINVAL; | |
930 | ||
931 | /* | |
932 | * neither in nor out is a pipe, setup an internal pipe attached to | |
933 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
934 | */ | |
935 | pipe = current->splice_pipe; | |
49570e9b | 936 | if (unlikely(!pipe)) { |
7bee130e | 937 | pipe = alloc_pipe_info(); |
b92ce558 JA |
938 | if (!pipe) |
939 | return -ENOMEM; | |
940 | ||
941 | /* | |
942 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 943 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
944 | * PIPE_READERS appropriately. |
945 | */ | |
946 | pipe->readers = 1; | |
947 | ||
948 | current->splice_pipe = pipe; | |
949 | } | |
950 | ||
951 | /* | |
73d62d83 | 952 | * Do the splice. |
b92ce558 JA |
953 | */ |
954 | ret = 0; | |
955 | bytes = 0; | |
c66ab6fa JA |
956 | len = sd->total_len; |
957 | flags = sd->flags; | |
958 | ||
959 | /* | |
960 | * Don't block on output, we have to drain the direct pipe. | |
961 | */ | |
962 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
0ff28d9f | 963 | more = sd->flags & SPLICE_F_MORE; |
b92ce558 JA |
964 | |
965 | while (len) { | |
51a92c0f | 966 | size_t read_len; |
a82c53a0 | 967 | loff_t pos = sd->pos, prev_pos = pos; |
b92ce558 | 968 | |
bcd4f3ac | 969 | ret = do_splice_to(in, &pos, pipe, len, flags); |
51a92c0f | 970 | if (unlikely(ret <= 0)) |
b92ce558 JA |
971 | goto out_release; |
972 | ||
973 | read_len = ret; | |
c66ab6fa | 974 | sd->total_len = read_len; |
b92ce558 | 975 | |
0ff28d9f CL |
976 | /* |
977 | * If more data is pending, set SPLICE_F_MORE | |
978 | * If this is the last data and SPLICE_F_MORE was not set | |
979 | * initially, clears it. | |
980 | */ | |
981 | if (read_len < len) | |
982 | sd->flags |= SPLICE_F_MORE; | |
983 | else if (!more) | |
984 | sd->flags &= ~SPLICE_F_MORE; | |
b92ce558 JA |
985 | /* |
986 | * NOTE: nonblocking mode only applies to the input. We | |
987 | * must not do the output in nonblocking mode as then we | |
988 | * could get stuck data in the internal pipe: | |
989 | */ | |
c66ab6fa | 990 | ret = actor(pipe, sd); |
a82c53a0 TZ |
991 | if (unlikely(ret <= 0)) { |
992 | sd->pos = prev_pos; | |
b92ce558 | 993 | goto out_release; |
a82c53a0 | 994 | } |
b92ce558 JA |
995 | |
996 | bytes += ret; | |
997 | len -= ret; | |
bcd4f3ac | 998 | sd->pos = pos; |
b92ce558 | 999 | |
a82c53a0 TZ |
1000 | if (ret < read_len) { |
1001 | sd->pos = prev_pos + ret; | |
51a92c0f | 1002 | goto out_release; |
a82c53a0 | 1003 | } |
b92ce558 JA |
1004 | } |
1005 | ||
9e97198d | 1006 | done: |
b92ce558 | 1007 | pipe->nrbufs = pipe->curbuf = 0; |
80848708 | 1008 | file_accessed(in); |
b92ce558 JA |
1009 | return bytes; |
1010 | ||
1011 | out_release: | |
1012 | /* | |
1013 | * If we did an incomplete transfer we must release | |
1014 | * the pipe buffers in question: | |
1015 | */ | |
35f3d14d | 1016 | for (i = 0; i < pipe->buffers; i++) { |
b92ce558 JA |
1017 | struct pipe_buffer *buf = pipe->bufs + i; |
1018 | ||
a779638c MS |
1019 | if (buf->ops) |
1020 | pipe_buf_release(pipe, buf); | |
b92ce558 | 1021 | } |
b92ce558 | 1022 | |
9e97198d JA |
1023 | if (!bytes) |
1024 | bytes = ret; | |
c66ab6fa | 1025 | |
9e97198d | 1026 | goto done; |
c66ab6fa JA |
1027 | } |
1028 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1029 | ||
1030 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1031 | struct splice_desc *sd) | |
1032 | { | |
6a14b90b | 1033 | struct file *file = sd->u.file; |
c66ab6fa | 1034 | |
7995bd28 | 1035 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
2cb4b05e | 1036 | sd->flags); |
c66ab6fa JA |
1037 | } |
1038 | ||
932cc6d4 JA |
1039 | /** |
1040 | * do_splice_direct - splices data directly between two files | |
1041 | * @in: file to splice from | |
1042 | * @ppos: input file offset | |
1043 | * @out: file to splice to | |
acdb37c3 | 1044 | * @opos: output file offset |
932cc6d4 JA |
1045 | * @len: number of bytes to splice |
1046 | * @flags: splice modifier flags | |
1047 | * | |
1048 | * Description: | |
1049 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1050 | * doing it in the application would incur an extra system call | |
1051 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1052 | * can splice directly through a process-private pipe. | |
1053 | * | |
1054 | */ | |
c66ab6fa | 1055 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
7995bd28 | 1056 | loff_t *opos, size_t len, unsigned int flags) |
c66ab6fa JA |
1057 | { |
1058 | struct splice_desc sd = { | |
1059 | .len = len, | |
1060 | .total_len = len, | |
1061 | .flags = flags, | |
1062 | .pos = *ppos, | |
6a14b90b | 1063 | .u.file = out, |
7995bd28 | 1064 | .opos = opos, |
c66ab6fa | 1065 | }; |
51a92c0f | 1066 | long ret; |
c66ab6fa | 1067 | |
18c67cb9 AV |
1068 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1069 | return -EBADF; | |
1070 | ||
1071 | if (unlikely(out->f_flags & O_APPEND)) | |
1072 | return -EINVAL; | |
1073 | ||
1074 | ret = rw_verify_area(WRITE, out, opos, len); | |
1075 | if (unlikely(ret < 0)) | |
1076 | return ret; | |
1077 | ||
c66ab6fa | 1078 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
51a92c0f | 1079 | if (ret > 0) |
a82c53a0 | 1080 | *ppos = sd.pos; |
51a92c0f | 1081 | |
c66ab6fa | 1082 | return ret; |
b92ce558 | 1083 | } |
1c118596 | 1084 | EXPORT_SYMBOL(do_splice_direct); |
b92ce558 | 1085 | |
8924feff AV |
1086 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) |
1087 | { | |
1088 | while (pipe->nrbufs == pipe->buffers) { | |
1089 | if (flags & SPLICE_F_NONBLOCK) | |
1090 | return -EAGAIN; | |
1091 | if (signal_pending(current)) | |
1092 | return -ERESTARTSYS; | |
1093 | pipe->waiting_writers++; | |
1094 | pipe_wait(pipe); | |
1095 | pipe->waiting_writers--; | |
1096 | } | |
1097 | return 0; | |
1098 | } | |
1099 | ||
7c77f0b3 MS |
1100 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1101 | struct pipe_inode_info *opipe, | |
1102 | size_t len, unsigned int flags); | |
ddac0d39 | 1103 | |
83f9135b JA |
1104 | /* |
1105 | * Determine where to splice to/from. | |
1106 | */ | |
529565dc IM |
1107 | static long do_splice(struct file *in, loff_t __user *off_in, |
1108 | struct file *out, loff_t __user *off_out, | |
1109 | size_t len, unsigned int flags) | |
5274f052 | 1110 | { |
7c77f0b3 MS |
1111 | struct pipe_inode_info *ipipe; |
1112 | struct pipe_inode_info *opipe; | |
7995bd28 | 1113 | loff_t offset; |
a4514ebd | 1114 | long ret; |
5274f052 | 1115 | |
71993e62 LT |
1116 | ipipe = get_pipe_info(in); |
1117 | opipe = get_pipe_info(out); | |
7c77f0b3 MS |
1118 | |
1119 | if (ipipe && opipe) { | |
1120 | if (off_in || off_out) | |
1121 | return -ESPIPE; | |
1122 | ||
1123 | if (!(in->f_mode & FMODE_READ)) | |
1124 | return -EBADF; | |
1125 | ||
1126 | if (!(out->f_mode & FMODE_WRITE)) | |
1127 | return -EBADF; | |
1128 | ||
1129 | /* Splicing to self would be fun, but... */ | |
1130 | if (ipipe == opipe) | |
1131 | return -EINVAL; | |
1132 | ||
1133 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); | |
1134 | } | |
1135 | ||
1136 | if (ipipe) { | |
529565dc IM |
1137 | if (off_in) |
1138 | return -ESPIPE; | |
b92ce558 | 1139 | if (off_out) { |
19c9a49b | 1140 | if (!(out->f_mode & FMODE_PWRITE)) |
b92ce558 | 1141 | return -EINVAL; |
cbb7e577 | 1142 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1143 | return -EFAULT; |
7995bd28 AV |
1144 | } else { |
1145 | offset = out->f_pos; | |
1146 | } | |
529565dc | 1147 | |
18c67cb9 AV |
1148 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1149 | return -EBADF; | |
1150 | ||
1151 | if (unlikely(out->f_flags & O_APPEND)) | |
1152 | return -EINVAL; | |
1153 | ||
1154 | ret = rw_verify_area(WRITE, out, &offset, len); | |
1155 | if (unlikely(ret < 0)) | |
1156 | return ret; | |
1157 | ||
500368f7 | 1158 | file_start_write(out); |
7995bd28 | 1159 | ret = do_splice_from(ipipe, out, &offset, len, flags); |
500368f7 | 1160 | file_end_write(out); |
a4514ebd | 1161 | |
7995bd28 AV |
1162 | if (!off_out) |
1163 | out->f_pos = offset; | |
1164 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) | |
a4514ebd JA |
1165 | ret = -EFAULT; |
1166 | ||
1167 | return ret; | |
529565dc | 1168 | } |
5274f052 | 1169 | |
7c77f0b3 | 1170 | if (opipe) { |
529565dc IM |
1171 | if (off_out) |
1172 | return -ESPIPE; | |
b92ce558 | 1173 | if (off_in) { |
19c9a49b | 1174 | if (!(in->f_mode & FMODE_PREAD)) |
b92ce558 | 1175 | return -EINVAL; |
cbb7e577 | 1176 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1177 | return -EFAULT; |
7995bd28 AV |
1178 | } else { |
1179 | offset = in->f_pos; | |
1180 | } | |
529565dc | 1181 | |
8924feff AV |
1182 | pipe_lock(opipe); |
1183 | ret = wait_for_space(opipe, flags); | |
1184 | if (!ret) | |
1185 | ret = do_splice_to(in, &offset, opipe, len, flags); | |
1186 | pipe_unlock(opipe); | |
1187 | if (ret > 0) | |
1188 | wakeup_pipe_readers(opipe); | |
7995bd28 AV |
1189 | if (!off_in) |
1190 | in->f_pos = offset; | |
1191 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) | |
a4514ebd JA |
1192 | ret = -EFAULT; |
1193 | ||
1194 | return ret; | |
529565dc | 1195 | } |
5274f052 JA |
1196 | |
1197 | return -EINVAL; | |
1198 | } | |
1199 | ||
79fddc4e AV |
1200 | static int iter_to_pipe(struct iov_iter *from, |
1201 | struct pipe_inode_info *pipe, | |
1202 | unsigned flags) | |
912d35f8 | 1203 | { |
79fddc4e AV |
1204 | struct pipe_buffer buf = { |
1205 | .ops = &user_page_pipe_buf_ops, | |
1206 | .flags = flags | |
1207 | }; | |
1208 | size_t total = 0; | |
1209 | int ret = 0; | |
1210 | bool failed = false; | |
1211 | ||
1212 | while (iov_iter_count(from) && !failed) { | |
1213 | struct page *pages[16]; | |
db85a9eb AV |
1214 | ssize_t copied; |
1215 | size_t start; | |
79fddc4e | 1216 | int n; |
db85a9eb | 1217 | |
79fddc4e AV |
1218 | copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start); |
1219 | if (copied <= 0) { | |
1220 | ret = copied; | |
1221 | break; | |
1222 | } | |
db85a9eb | 1223 | |
79fddc4e | 1224 | for (n = 0; copied; n++, start = 0) { |
db85a9eb | 1225 | int size = min_t(int, copied, PAGE_SIZE - start); |
79fddc4e AV |
1226 | if (!failed) { |
1227 | buf.page = pages[n]; | |
1228 | buf.offset = start; | |
1229 | buf.len = size; | |
1230 | ret = add_to_pipe(pipe, &buf); | |
1231 | if (unlikely(ret < 0)) { | |
1232 | failed = true; | |
1233 | } else { | |
1234 | iov_iter_advance(from, ret); | |
1235 | total += ret; | |
1236 | } | |
1237 | } else { | |
1238 | put_page(pages[n]); | |
1239 | } | |
db85a9eb | 1240 | copied -= size; |
912d35f8 | 1241 | } |
912d35f8 | 1242 | } |
79fddc4e | 1243 | return total ? total : ret; |
912d35f8 JA |
1244 | } |
1245 | ||
6a14b90b JA |
1246 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1247 | struct splice_desc *sd) | |
1248 | { | |
6130f531 AV |
1249 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
1250 | return n == sd->len ? n : -EFAULT; | |
6a14b90b JA |
1251 | } |
1252 | ||
1253 | /* | |
1254 | * For lack of a better implementation, implement vmsplice() to userspace | |
1255 | * as a simple copy of the pipes pages to the user iov. | |
1256 | */ | |
6130f531 | 1257 | static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov, |
6a14b90b JA |
1258 | unsigned long nr_segs, unsigned int flags) |
1259 | { | |
1260 | struct pipe_inode_info *pipe; | |
1261 | struct splice_desc sd; | |
6a14b90b | 1262 | long ret; |
6130f531 AV |
1263 | struct iovec iovstack[UIO_FASTIOV]; |
1264 | struct iovec *iov = iovstack; | |
1265 | struct iov_iter iter; | |
6a14b90b | 1266 | |
71993e62 | 1267 | pipe = get_pipe_info(file); |
6a14b90b JA |
1268 | if (!pipe) |
1269 | return -EBADF; | |
1270 | ||
345995fa AV |
1271 | ret = import_iovec(READ, uiov, nr_segs, |
1272 | ARRAY_SIZE(iovstack), &iov, &iter); | |
1273 | if (ret < 0) | |
1274 | return ret; | |
6a14b90b | 1275 | |
345995fa | 1276 | sd.total_len = iov_iter_count(&iter); |
6130f531 | 1277 | sd.len = 0; |
6130f531 AV |
1278 | sd.flags = flags; |
1279 | sd.u.data = &iter; | |
1280 | sd.pos = 0; | |
6a14b90b | 1281 | |
345995fa AV |
1282 | if (sd.total_len) { |
1283 | pipe_lock(pipe); | |
1284 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1285 | pipe_unlock(pipe); | |
1286 | } | |
6a14b90b | 1287 | |
345995fa | 1288 | kfree(iov); |
6a14b90b JA |
1289 | return ret; |
1290 | } | |
1291 | ||
912d35f8 JA |
1292 | /* |
1293 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1294 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1295 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1296 | */ |
db85a9eb | 1297 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov, |
6a14b90b | 1298 | unsigned long nr_segs, unsigned int flags) |
912d35f8 | 1299 | { |
ddac0d39 | 1300 | struct pipe_inode_info *pipe; |
db85a9eb AV |
1301 | struct iovec iovstack[UIO_FASTIOV]; |
1302 | struct iovec *iov = iovstack; | |
1303 | struct iov_iter from; | |
35f3d14d | 1304 | long ret; |
79fddc4e AV |
1305 | unsigned buf_flag = 0; |
1306 | ||
1307 | if (flags & SPLICE_F_GIFT) | |
1308 | buf_flag = PIPE_BUF_FLAG_GIFT; | |
912d35f8 | 1309 | |
71993e62 | 1310 | pipe = get_pipe_info(file); |
ddac0d39 | 1311 | if (!pipe) |
912d35f8 | 1312 | return -EBADF; |
912d35f8 | 1313 | |
db85a9eb AV |
1314 | ret = import_iovec(WRITE, uiov, nr_segs, |
1315 | ARRAY_SIZE(iovstack), &iov, &from); | |
1316 | if (ret < 0) | |
1317 | return ret; | |
1318 | ||
8924feff AV |
1319 | pipe_lock(pipe); |
1320 | ret = wait_for_space(pipe, flags); | |
79fddc4e AV |
1321 | if (!ret) |
1322 | ret = iter_to_pipe(&from, pipe, buf_flag); | |
8924feff AV |
1323 | pipe_unlock(pipe); |
1324 | if (ret > 0) | |
1325 | wakeup_pipe_readers(pipe); | |
db85a9eb | 1326 | kfree(iov); |
35f3d14d | 1327 | return ret; |
912d35f8 JA |
1328 | } |
1329 | ||
6a14b90b JA |
1330 | /* |
1331 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1332 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1333 | * operation that can be supported without any funky alignment restrictions | |
1334 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1335 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1336 | * solutions for that: | |
1337 | * | |
1338 | * - memcpy() the data internally, at which point we might as well just | |
1339 | * do a regular read() on the buffer anyway. | |
1340 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1341 | * has restriction limitations on both ends of the pipe). | |
1342 | * | |
1343 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1344 | * | |
1345 | */ | |
836f92ad HC |
1346 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1347 | unsigned long, nr_segs, unsigned int, flags) | |
912d35f8 | 1348 | { |
2903ff01 | 1349 | struct fd f; |
912d35f8 | 1350 | long error; |
912d35f8 | 1351 | |
6a14b90b JA |
1352 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1353 | return -EINVAL; | |
1354 | else if (unlikely(!nr_segs)) | |
1355 | return 0; | |
1356 | ||
912d35f8 | 1357 | error = -EBADF; |
2903ff01 AV |
1358 | f = fdget(fd); |
1359 | if (f.file) { | |
1360 | if (f.file->f_mode & FMODE_WRITE) | |
1361 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); | |
1362 | else if (f.file->f_mode & FMODE_READ) | |
1363 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); | |
1364 | ||
1365 | fdput(f); | |
912d35f8 JA |
1366 | } |
1367 | ||
1368 | return error; | |
1369 | } | |
1370 | ||
76b021d0 AV |
1371 | #ifdef CONFIG_COMPAT |
1372 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, | |
1373 | unsigned int, nr_segs, unsigned int, flags) | |
1374 | { | |
1375 | unsigned i; | |
1376 | struct iovec __user *iov; | |
1377 | if (nr_segs > UIO_MAXIOV) | |
1378 | return -EINVAL; | |
1379 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); | |
1380 | for (i = 0; i < nr_segs; i++) { | |
1381 | struct compat_iovec v; | |
1382 | if (get_user(v.iov_base, &iov32[i].iov_base) || | |
1383 | get_user(v.iov_len, &iov32[i].iov_len) || | |
1384 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || | |
1385 | put_user(v.iov_len, &iov[i].iov_len)) | |
1386 | return -EFAULT; | |
1387 | } | |
1388 | return sys_vmsplice(fd, iov, nr_segs, flags); | |
1389 | } | |
1390 | #endif | |
1391 | ||
836f92ad HC |
1392 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1393 | int, fd_out, loff_t __user *, off_out, | |
1394 | size_t, len, unsigned int, flags) | |
5274f052 | 1395 | { |
2903ff01 | 1396 | struct fd in, out; |
5274f052 | 1397 | long error; |
5274f052 JA |
1398 | |
1399 | if (unlikely(!len)) | |
1400 | return 0; | |
1401 | ||
1402 | error = -EBADF; | |
2903ff01 AV |
1403 | in = fdget(fd_in); |
1404 | if (in.file) { | |
1405 | if (in.file->f_mode & FMODE_READ) { | |
1406 | out = fdget(fd_out); | |
1407 | if (out.file) { | |
1408 | if (out.file->f_mode & FMODE_WRITE) | |
1409 | error = do_splice(in.file, off_in, | |
1410 | out.file, off_out, | |
529565dc | 1411 | len, flags); |
2903ff01 | 1412 | fdput(out); |
5274f052 JA |
1413 | } |
1414 | } | |
2903ff01 | 1415 | fdput(in); |
5274f052 | 1416 | } |
5274f052 JA |
1417 | return error; |
1418 | } | |
70524490 | 1419 | |
aadd06e5 JA |
1420 | /* |
1421 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1422 | * return an appropriate error. | |
1423 | */ | |
7c77f0b3 | 1424 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1425 | { |
1426 | int ret; | |
1427 | ||
1428 | /* | |
1429 | * Check ->nrbufs without the inode lock first. This function | |
1430 | * is speculative anyways, so missing one is ok. | |
1431 | */ | |
1432 | if (pipe->nrbufs) | |
1433 | return 0; | |
1434 | ||
1435 | ret = 0; | |
61e0d47c | 1436 | pipe_lock(pipe); |
aadd06e5 JA |
1437 | |
1438 | while (!pipe->nrbufs) { | |
1439 | if (signal_pending(current)) { | |
1440 | ret = -ERESTARTSYS; | |
1441 | break; | |
1442 | } | |
1443 | if (!pipe->writers) | |
1444 | break; | |
1445 | if (!pipe->waiting_writers) { | |
1446 | if (flags & SPLICE_F_NONBLOCK) { | |
1447 | ret = -EAGAIN; | |
1448 | break; | |
1449 | } | |
1450 | } | |
1451 | pipe_wait(pipe); | |
1452 | } | |
1453 | ||
61e0d47c | 1454 | pipe_unlock(pipe); |
aadd06e5 JA |
1455 | return ret; |
1456 | } | |
1457 | ||
1458 | /* | |
1459 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1460 | * return an appropriate error. | |
1461 | */ | |
7c77f0b3 | 1462 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1463 | { |
1464 | int ret; | |
1465 | ||
1466 | /* | |
1467 | * Check ->nrbufs without the inode lock first. This function | |
1468 | * is speculative anyways, so missing one is ok. | |
1469 | */ | |
35f3d14d | 1470 | if (pipe->nrbufs < pipe->buffers) |
aadd06e5 JA |
1471 | return 0; |
1472 | ||
1473 | ret = 0; | |
61e0d47c | 1474 | pipe_lock(pipe); |
aadd06e5 | 1475 | |
35f3d14d | 1476 | while (pipe->nrbufs >= pipe->buffers) { |
aadd06e5 JA |
1477 | if (!pipe->readers) { |
1478 | send_sig(SIGPIPE, current, 0); | |
1479 | ret = -EPIPE; | |
1480 | break; | |
1481 | } | |
1482 | if (flags & SPLICE_F_NONBLOCK) { | |
1483 | ret = -EAGAIN; | |
1484 | break; | |
1485 | } | |
1486 | if (signal_pending(current)) { | |
1487 | ret = -ERESTARTSYS; | |
1488 | break; | |
1489 | } | |
1490 | pipe->waiting_writers++; | |
1491 | pipe_wait(pipe); | |
1492 | pipe->waiting_writers--; | |
1493 | } | |
1494 | ||
61e0d47c | 1495 | pipe_unlock(pipe); |
aadd06e5 JA |
1496 | return ret; |
1497 | } | |
1498 | ||
7c77f0b3 MS |
1499 | /* |
1500 | * Splice contents of ipipe to opipe. | |
1501 | */ | |
1502 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1503 | struct pipe_inode_info *opipe, | |
1504 | size_t len, unsigned int flags) | |
1505 | { | |
1506 | struct pipe_buffer *ibuf, *obuf; | |
1507 | int ret = 0, nbuf; | |
1508 | bool input_wakeup = false; | |
1509 | ||
1510 | ||
1511 | retry: | |
1512 | ret = ipipe_prep(ipipe, flags); | |
1513 | if (ret) | |
1514 | return ret; | |
1515 | ||
1516 | ret = opipe_prep(opipe, flags); | |
1517 | if (ret) | |
1518 | return ret; | |
1519 | ||
1520 | /* | |
1521 | * Potential ABBA deadlock, work around it by ordering lock | |
1522 | * grabbing by pipe info address. Otherwise two different processes | |
1523 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1524 | */ | |
1525 | pipe_double_lock(ipipe, opipe); | |
1526 | ||
1527 | do { | |
1528 | if (!opipe->readers) { | |
1529 | send_sig(SIGPIPE, current, 0); | |
1530 | if (!ret) | |
1531 | ret = -EPIPE; | |
1532 | break; | |
1533 | } | |
1534 | ||
1535 | if (!ipipe->nrbufs && !ipipe->writers) | |
1536 | break; | |
1537 | ||
1538 | /* | |
1539 | * Cannot make any progress, because either the input | |
1540 | * pipe is empty or the output pipe is full. | |
1541 | */ | |
35f3d14d | 1542 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
7c77f0b3 MS |
1543 | /* Already processed some buffers, break */ |
1544 | if (ret) | |
1545 | break; | |
1546 | ||
1547 | if (flags & SPLICE_F_NONBLOCK) { | |
1548 | ret = -EAGAIN; | |
1549 | break; | |
1550 | } | |
1551 | ||
1552 | /* | |
1553 | * We raced with another reader/writer and haven't | |
1554 | * managed to process any buffers. A zero return | |
1555 | * value means EOF, so retry instead. | |
1556 | */ | |
1557 | pipe_unlock(ipipe); | |
1558 | pipe_unlock(opipe); | |
1559 | goto retry; | |
1560 | } | |
1561 | ||
1562 | ibuf = ipipe->bufs + ipipe->curbuf; | |
35f3d14d | 1563 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
7c77f0b3 MS |
1564 | obuf = opipe->bufs + nbuf; |
1565 | ||
1566 | if (len >= ibuf->len) { | |
1567 | /* | |
1568 | * Simply move the whole buffer from ipipe to opipe | |
1569 | */ | |
1570 | *obuf = *ibuf; | |
1571 | ibuf->ops = NULL; | |
1572 | opipe->nrbufs++; | |
35f3d14d | 1573 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
7c77f0b3 MS |
1574 | ipipe->nrbufs--; |
1575 | input_wakeup = true; | |
1576 | } else { | |
1577 | /* | |
1578 | * Get a reference to this pipe buffer, | |
1579 | * so we can copy the contents over. | |
1580 | */ | |
7bf2d1df | 1581 | pipe_buf_get(ipipe, ibuf); |
7c77f0b3 MS |
1582 | *obuf = *ibuf; |
1583 | ||
1584 | /* | |
1585 | * Don't inherit the gift flag, we need to | |
1586 | * prevent multiple steals of this page. | |
1587 | */ | |
1588 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1589 | ||
1590 | obuf->len = len; | |
1591 | opipe->nrbufs++; | |
1592 | ibuf->offset += obuf->len; | |
1593 | ibuf->len -= obuf->len; | |
1594 | } | |
1595 | ret += obuf->len; | |
1596 | len -= obuf->len; | |
1597 | } while (len); | |
1598 | ||
1599 | pipe_unlock(ipipe); | |
1600 | pipe_unlock(opipe); | |
1601 | ||
1602 | /* | |
1603 | * If we put data in the output pipe, wakeup any potential readers. | |
1604 | */ | |
825cdcb1 NK |
1605 | if (ret > 0) |
1606 | wakeup_pipe_readers(opipe); | |
1607 | ||
7c77f0b3 MS |
1608 | if (input_wakeup) |
1609 | wakeup_pipe_writers(ipipe); | |
1610 | ||
1611 | return ret; | |
1612 | } | |
1613 | ||
70524490 JA |
1614 | /* |
1615 | * Link contents of ipipe to opipe. | |
1616 | */ | |
1617 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1618 | struct pipe_inode_info *opipe, | |
1619 | size_t len, unsigned int flags) | |
1620 | { | |
1621 | struct pipe_buffer *ibuf, *obuf; | |
aadd06e5 | 1622 | int ret = 0, i = 0, nbuf; |
70524490 JA |
1623 | |
1624 | /* | |
1625 | * Potential ABBA deadlock, work around it by ordering lock | |
61e0d47c | 1626 | * grabbing by pipe info address. Otherwise two different processes |
70524490 JA |
1627 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1628 | */ | |
61e0d47c | 1629 | pipe_double_lock(ipipe, opipe); |
70524490 | 1630 | |
aadd06e5 | 1631 | do { |
70524490 JA |
1632 | if (!opipe->readers) { |
1633 | send_sig(SIGPIPE, current, 0); | |
1634 | if (!ret) | |
1635 | ret = -EPIPE; | |
1636 | break; | |
1637 | } | |
70524490 | 1638 | |
aadd06e5 JA |
1639 | /* |
1640 | * If we have iterated all input buffers or ran out of | |
1641 | * output room, break. | |
1642 | */ | |
35f3d14d | 1643 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
aadd06e5 | 1644 | break; |
70524490 | 1645 | |
35f3d14d JA |
1646 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
1647 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
70524490 JA |
1648 | |
1649 | /* | |
aadd06e5 JA |
1650 | * Get a reference to this pipe buffer, |
1651 | * so we can copy the contents over. | |
70524490 | 1652 | */ |
7bf2d1df | 1653 | pipe_buf_get(ipipe, ibuf); |
aadd06e5 JA |
1654 | |
1655 | obuf = opipe->bufs + nbuf; | |
1656 | *obuf = *ibuf; | |
1657 | ||
2a27250e | 1658 | /* |
aadd06e5 JA |
1659 | * Don't inherit the gift flag, we need to |
1660 | * prevent multiple steals of this page. | |
2a27250e | 1661 | */ |
aadd06e5 | 1662 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
70524490 | 1663 | |
aadd06e5 JA |
1664 | if (obuf->len > len) |
1665 | obuf->len = len; | |
70524490 | 1666 | |
aadd06e5 JA |
1667 | opipe->nrbufs++; |
1668 | ret += obuf->len; | |
1669 | len -= obuf->len; | |
1670 | i++; | |
1671 | } while (len); | |
70524490 | 1672 | |
02cf01ae JA |
1673 | /* |
1674 | * return EAGAIN if we have the potential of some data in the | |
1675 | * future, otherwise just return 0 | |
1676 | */ | |
1677 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
1678 | ret = -EAGAIN; | |
1679 | ||
61e0d47c MS |
1680 | pipe_unlock(ipipe); |
1681 | pipe_unlock(opipe); | |
70524490 | 1682 | |
aadd06e5 JA |
1683 | /* |
1684 | * If we put data in the output pipe, wakeup any potential readers. | |
1685 | */ | |
825cdcb1 NK |
1686 | if (ret > 0) |
1687 | wakeup_pipe_readers(opipe); | |
70524490 JA |
1688 | |
1689 | return ret; | |
1690 | } | |
1691 | ||
1692 | /* | |
1693 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1694 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1695 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1696 | * applicable one is SPLICE_F_NONBLOCK. | |
1697 | */ | |
1698 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1699 | unsigned int flags) | |
1700 | { | |
71993e62 LT |
1701 | struct pipe_inode_info *ipipe = get_pipe_info(in); |
1702 | struct pipe_inode_info *opipe = get_pipe_info(out); | |
aadd06e5 | 1703 | int ret = -EINVAL; |
70524490 JA |
1704 | |
1705 | /* | |
aadd06e5 JA |
1706 | * Duplicate the contents of ipipe to opipe without actually |
1707 | * copying the data. | |
70524490 | 1708 | */ |
aadd06e5 JA |
1709 | if (ipipe && opipe && ipipe != opipe) { |
1710 | /* | |
1711 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1712 | * ordering doesn't really matter. | |
1713 | */ | |
7c77f0b3 | 1714 | ret = ipipe_prep(ipipe, flags); |
aadd06e5 | 1715 | if (!ret) { |
7c77f0b3 | 1716 | ret = opipe_prep(opipe, flags); |
02cf01ae | 1717 | if (!ret) |
aadd06e5 | 1718 | ret = link_pipe(ipipe, opipe, len, flags); |
aadd06e5 JA |
1719 | } |
1720 | } | |
70524490 | 1721 | |
aadd06e5 | 1722 | return ret; |
70524490 JA |
1723 | } |
1724 | ||
836f92ad | 1725 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
70524490 | 1726 | { |
2903ff01 AV |
1727 | struct fd in; |
1728 | int error; | |
70524490 JA |
1729 | |
1730 | if (unlikely(!len)) | |
1731 | return 0; | |
1732 | ||
1733 | error = -EBADF; | |
2903ff01 AV |
1734 | in = fdget(fdin); |
1735 | if (in.file) { | |
1736 | if (in.file->f_mode & FMODE_READ) { | |
1737 | struct fd out = fdget(fdout); | |
1738 | if (out.file) { | |
1739 | if (out.file->f_mode & FMODE_WRITE) | |
1740 | error = do_tee(in.file, out.file, | |
1741 | len, flags); | |
1742 | fdput(out); | |
70524490 JA |
1743 | } |
1744 | } | |
2903ff01 | 1745 | fdput(in); |
70524490 JA |
1746 | } |
1747 | ||
1748 | return error; | |
1749 | } |