Commit | Line | Data |
---|---|---|
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; | |
302 | loff_t isize; | |
303 | int idx, ret; | |
be64f884 | 304 | |
d366d398 JA |
305 | isize = i_size_read(in->f_mapping->host); |
306 | if (unlikely(*ppos >= isize)) | |
307 | return 0; | |
308 | ||
82c156f8 AV |
309 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len); |
310 | idx = to.idx; | |
311 | init_sync_kiocb(&kiocb, in); | |
312 | kiocb.ki_pos = *ppos; | |
313 | ret = in->f_op->read_iter(&kiocb, &to); | |
723590ed | 314 | if (ret > 0) { |
82c156f8 | 315 | *ppos = kiocb.ki_pos; |
723590ed | 316 | file_accessed(in); |
82c156f8 AV |
317 | } else if (ret < 0) { |
318 | if (WARN_ON(to.idx != idx || to.iov_offset)) { | |
319 | /* | |
320 | * a bogus ->read_iter() has copied something and still | |
321 | * returned an error instead of a short read. | |
322 | */ | |
323 | to.idx = idx; | |
324 | to.iov_offset = 0; | |
325 | iov_iter_advance(&to, 0); /* to free what was emitted */ | |
326 | } | |
327 | /* | |
328 | * callers of ->splice_read() expect -EAGAIN on | |
329 | * "can't put anything in there", rather than -EFAULT. | |
330 | */ | |
331 | if (ret == -EFAULT) | |
332 | ret = -EAGAIN; | |
723590ed | 333 | } |
5274f052 JA |
334 | |
335 | return ret; | |
336 | } | |
059a8f37 JA |
337 | EXPORT_SYMBOL(generic_file_splice_read); |
338 | ||
241699cd | 339 | const struct pipe_buf_operations default_pipe_buf_ops = { |
6818173b | 340 | .can_merge = 0, |
6818173b MS |
341 | .confirm = generic_pipe_buf_confirm, |
342 | .release = generic_pipe_buf_release, | |
343 | .steal = generic_pipe_buf_steal, | |
344 | .get = generic_pipe_buf_get, | |
345 | }; | |
346 | ||
28a625cb MS |
347 | static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe, |
348 | struct pipe_buffer *buf) | |
349 | { | |
350 | return 1; | |
351 | } | |
352 | ||
353 | /* Pipe buffer operations for a socket and similar. */ | |
354 | const struct pipe_buf_operations nosteal_pipe_buf_ops = { | |
355 | .can_merge = 0, | |
28a625cb MS |
356 | .confirm = generic_pipe_buf_confirm, |
357 | .release = generic_pipe_buf_release, | |
358 | .steal = generic_pipe_buf_nosteal, | |
359 | .get = generic_pipe_buf_get, | |
360 | }; | |
361 | EXPORT_SYMBOL(nosteal_pipe_buf_ops); | |
362 | ||
523ac9af | 363 | static ssize_t kernel_readv(struct file *file, const struct kvec *vec, |
6818173b MS |
364 | unsigned long vlen, loff_t offset) |
365 | { | |
366 | mm_segment_t old_fs; | |
367 | loff_t pos = offset; | |
368 | ssize_t res; | |
369 | ||
370 | old_fs = get_fs(); | |
371 | set_fs(get_ds()); | |
372 | /* The cast to a user pointer is valid due to the set_fs() */ | |
793b80ef | 373 | res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0); |
6818173b MS |
374 | set_fs(old_fs); |
375 | ||
376 | return res; | |
377 | } | |
378 | ||
7bb307e8 | 379 | ssize_t kernel_write(struct file *file, const char *buf, size_t count, |
b2858d7d | 380 | loff_t pos) |
0b0a47f5 MS |
381 | { |
382 | mm_segment_t old_fs; | |
383 | ssize_t res; | |
384 | ||
385 | old_fs = get_fs(); | |
386 | set_fs(get_ds()); | |
387 | /* The cast to a user pointer is valid due to the set_fs() */ | |
7bb307e8 | 388 | res = vfs_write(file, (__force const char __user *)buf, count, &pos); |
0b0a47f5 MS |
389 | set_fs(old_fs); |
390 | ||
391 | return res; | |
392 | } | |
7bb307e8 | 393 | EXPORT_SYMBOL(kernel_write); |
0b0a47f5 | 394 | |
82c156f8 | 395 | static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, |
6818173b MS |
396 | struct pipe_inode_info *pipe, size_t len, |
397 | unsigned int flags) | |
398 | { | |
523ac9af AV |
399 | struct kvec *vec, __vec[PIPE_DEF_BUFFERS]; |
400 | struct iov_iter to; | |
401 | struct page **pages; | |
6818173b | 402 | unsigned int nr_pages; |
523ac9af | 403 | size_t offset, dummy, copied = 0; |
6818173b | 404 | ssize_t res; |
6818173b | 405 | int i; |
35f3d14d | 406 | |
523ac9af AV |
407 | if (pipe->nrbufs == pipe->buffers) |
408 | return -EAGAIN; | |
35f3d14d | 409 | |
523ac9af AV |
410 | /* |
411 | * Try to keep page boundaries matching to source pagecache ones - | |
412 | * it probably won't be much help, but... | |
413 | */ | |
09cbfeaf | 414 | offset = *ppos & ~PAGE_MASK; |
6818173b | 415 | |
523ac9af | 416 | iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len + offset); |
6818173b | 417 | |
523ac9af AV |
418 | res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &dummy); |
419 | if (res <= 0) | |
420 | return -ENOMEM; | |
6818173b | 421 | |
523ac9af | 422 | nr_pages = res / PAGE_SIZE; |
6818173b | 423 | |
523ac9af AV |
424 | vec = __vec; |
425 | if (nr_pages > PIPE_DEF_BUFFERS) { | |
426 | vec = kmalloc(nr_pages * sizeof(struct kvec), GFP_KERNEL); | |
427 | if (unlikely(!vec)) { | |
428 | res = -ENOMEM; | |
429 | goto out; | |
430 | } | |
77f6bf57 | 431 | } |
6818173b | 432 | |
523ac9af AV |
433 | pipe->bufs[to.idx].offset = offset; |
434 | pipe->bufs[to.idx].len -= offset; | |
435 | ||
436 | for (i = 0; i < nr_pages; i++) { | |
437 | size_t this_len = min_t(size_t, len, PAGE_SIZE - offset); | |
438 | vec[i].iov_base = page_address(pages[i]) + offset; | |
439 | vec[i].iov_len = this_len; | |
440 | len -= this_len; | |
441 | offset = 0; | |
6818173b | 442 | } |
6818173b | 443 | |
523ac9af AV |
444 | res = kernel_readv(in, vec, nr_pages, *ppos); |
445 | if (res > 0) { | |
446 | copied = res; | |
6818173b | 447 | *ppos += res; |
523ac9af | 448 | } |
6818173b | 449 | |
35f3d14d JA |
450 | if (vec != __vec) |
451 | kfree(vec); | |
523ac9af AV |
452 | out: |
453 | for (i = 0; i < nr_pages; i++) | |
454 | put_page(pages[i]); | |
455 | kvfree(pages); | |
456 | iov_iter_advance(&to, copied); /* truncates and discards */ | |
6818173b | 457 | return res; |
6818173b | 458 | } |
6818173b | 459 | |
5274f052 | 460 | /* |
4f6f0bd2 | 461 | * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
016b661e | 462 | * using sendpage(). Return the number of bytes sent. |
5274f052 | 463 | */ |
76ad4d11 | 464 | static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
5274f052 JA |
465 | struct pipe_buffer *buf, struct splice_desc *sd) |
466 | { | |
6a14b90b | 467 | struct file *file = sd->u.file; |
5274f052 | 468 | loff_t pos = sd->pos; |
a8adbe37 | 469 | int more; |
5274f052 | 470 | |
72c2d531 | 471 | if (!likely(file->f_op->sendpage)) |
a8adbe37 MM |
472 | return -EINVAL; |
473 | ||
35f9c09f | 474 | more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
ae62ca7b ED |
475 | |
476 | if (sd->len < sd->total_len && pipe->nrbufs > 1) | |
35f9c09f | 477 | more |= MSG_SENDPAGE_NOTLAST; |
ae62ca7b | 478 | |
a8adbe37 MM |
479 | return file->f_op->sendpage(file, buf->page, buf->offset, |
480 | sd->len, &pos, more); | |
5274f052 JA |
481 | } |
482 | ||
b3c2d2dd MS |
483 | static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
484 | { | |
485 | smp_mb(); | |
486 | if (waitqueue_active(&pipe->wait)) | |
487 | wake_up_interruptible(&pipe->wait); | |
488 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); | |
489 | } | |
490 | ||
932cc6d4 | 491 | /** |
b3c2d2dd | 492 | * splice_from_pipe_feed - feed available data from a pipe to a file |
932cc6d4 JA |
493 | * @pipe: pipe to splice from |
494 | * @sd: information to @actor | |
495 | * @actor: handler that splices the data | |
496 | * | |
497 | * Description: | |
b3c2d2dd MS |
498 | * This function loops over the pipe and calls @actor to do the |
499 | * actual moving of a single struct pipe_buffer to the desired | |
500 | * destination. It returns when there's no more buffers left in | |
501 | * the pipe or if the requested number of bytes (@sd->total_len) | |
502 | * have been copied. It returns a positive number (one) if the | |
503 | * pipe needs to be filled with more data, zero if the required | |
504 | * number of bytes have been copied and -errno on error. | |
932cc6d4 | 505 | * |
b3c2d2dd MS |
506 | * This, together with splice_from_pipe_{begin,end,next}, may be |
507 | * used to implement the functionality of __splice_from_pipe() when | |
508 | * locking is required around copying the pipe buffers to the | |
509 | * destination. | |
83f9135b | 510 | */ |
96f9bc8f | 511 | static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
b3c2d2dd | 512 | splice_actor *actor) |
5274f052 | 513 | { |
b3c2d2dd | 514 | int ret; |
5274f052 | 515 | |
b3c2d2dd MS |
516 | while (pipe->nrbufs) { |
517 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
5274f052 | 518 | |
b3c2d2dd MS |
519 | sd->len = buf->len; |
520 | if (sd->len > sd->total_len) | |
521 | sd->len = sd->total_len; | |
5274f052 | 522 | |
a8adbe37 MM |
523 | ret = buf->ops->confirm(pipe, buf); |
524 | if (unlikely(ret)) { | |
b3c2d2dd MS |
525 | if (ret == -ENODATA) |
526 | ret = 0; | |
527 | return ret; | |
528 | } | |
a8adbe37 MM |
529 | |
530 | ret = actor(pipe, buf, sd); | |
531 | if (ret <= 0) | |
532 | return ret; | |
533 | ||
b3c2d2dd MS |
534 | buf->offset += ret; |
535 | buf->len -= ret; | |
536 | ||
537 | sd->num_spliced += ret; | |
538 | sd->len -= ret; | |
539 | sd->pos += ret; | |
540 | sd->total_len -= ret; | |
541 | ||
542 | if (!buf->len) { | |
a779638c | 543 | pipe_buf_release(pipe, buf); |
35f3d14d | 544 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
b3c2d2dd | 545 | pipe->nrbufs--; |
6447a3cf | 546 | if (pipe->files) |
b3c2d2dd MS |
547 | sd->need_wakeup = true; |
548 | } | |
5274f052 | 549 | |
b3c2d2dd MS |
550 | if (!sd->total_len) |
551 | return 0; | |
552 | } | |
5274f052 | 553 | |
b3c2d2dd MS |
554 | return 1; |
555 | } | |
5274f052 | 556 | |
b3c2d2dd MS |
557 | /** |
558 | * splice_from_pipe_next - wait for some data to splice from | |
559 | * @pipe: pipe to splice from | |
560 | * @sd: information about the splice operation | |
561 | * | |
562 | * Description: | |
563 | * This function will wait for some data and return a positive | |
564 | * value (one) if pipe buffers are available. It will return zero | |
565 | * or -errno if no more data needs to be spliced. | |
566 | */ | |
96f9bc8f | 567 | static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd | 568 | { |
c725bfce JK |
569 | /* |
570 | * Check for signal early to make process killable when there are | |
571 | * always buffers available | |
572 | */ | |
573 | if (signal_pending(current)) | |
574 | return -ERESTARTSYS; | |
575 | ||
b3c2d2dd MS |
576 | while (!pipe->nrbufs) { |
577 | if (!pipe->writers) | |
578 | return 0; | |
016b661e | 579 | |
b3c2d2dd MS |
580 | if (!pipe->waiting_writers && sd->num_spliced) |
581 | return 0; | |
73d62d83 | 582 | |
b3c2d2dd MS |
583 | if (sd->flags & SPLICE_F_NONBLOCK) |
584 | return -EAGAIN; | |
5274f052 | 585 | |
b3c2d2dd MS |
586 | if (signal_pending(current)) |
587 | return -ERESTARTSYS; | |
5274f052 | 588 | |
b3c2d2dd MS |
589 | if (sd->need_wakeup) { |
590 | wakeup_pipe_writers(pipe); | |
591 | sd->need_wakeup = false; | |
5274f052 JA |
592 | } |
593 | ||
b3c2d2dd MS |
594 | pipe_wait(pipe); |
595 | } | |
29e35094 | 596 | |
b3c2d2dd MS |
597 | return 1; |
598 | } | |
5274f052 | 599 | |
b3c2d2dd MS |
600 | /** |
601 | * splice_from_pipe_begin - start splicing from pipe | |
b80901bb | 602 | * @sd: information about the splice operation |
b3c2d2dd MS |
603 | * |
604 | * Description: | |
605 | * This function should be called before a loop containing | |
606 | * splice_from_pipe_next() and splice_from_pipe_feed() to | |
607 | * initialize the necessary fields of @sd. | |
608 | */ | |
96f9bc8f | 609 | static void splice_from_pipe_begin(struct splice_desc *sd) |
b3c2d2dd MS |
610 | { |
611 | sd->num_spliced = 0; | |
612 | sd->need_wakeup = false; | |
613 | } | |
5274f052 | 614 | |
b3c2d2dd MS |
615 | /** |
616 | * splice_from_pipe_end - finish splicing from pipe | |
617 | * @pipe: pipe to splice from | |
618 | * @sd: information about the splice operation | |
619 | * | |
620 | * Description: | |
621 | * This function will wake up pipe writers if necessary. It should | |
622 | * be called after a loop containing splice_from_pipe_next() and | |
623 | * splice_from_pipe_feed(). | |
624 | */ | |
96f9bc8f | 625 | static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
b3c2d2dd MS |
626 | { |
627 | if (sd->need_wakeup) | |
628 | wakeup_pipe_writers(pipe); | |
629 | } | |
5274f052 | 630 | |
b3c2d2dd MS |
631 | /** |
632 | * __splice_from_pipe - splice data from a pipe to given actor | |
633 | * @pipe: pipe to splice from | |
634 | * @sd: information to @actor | |
635 | * @actor: handler that splices the data | |
636 | * | |
637 | * Description: | |
638 | * This function does little more than loop over the pipe and call | |
639 | * @actor to do the actual moving of a single struct pipe_buffer to | |
640 | * the desired destination. See pipe_to_file, pipe_to_sendpage, or | |
641 | * pipe_to_user. | |
642 | * | |
643 | */ | |
644 | ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, | |
645 | splice_actor *actor) | |
646 | { | |
647 | int ret; | |
5274f052 | 648 | |
b3c2d2dd MS |
649 | splice_from_pipe_begin(sd); |
650 | do { | |
c2489e07 | 651 | cond_resched(); |
b3c2d2dd MS |
652 | ret = splice_from_pipe_next(pipe, sd); |
653 | if (ret > 0) | |
654 | ret = splice_from_pipe_feed(pipe, sd, actor); | |
655 | } while (ret > 0); | |
656 | splice_from_pipe_end(pipe, sd); | |
657 | ||
658 | return sd->num_spliced ? sd->num_spliced : ret; | |
5274f052 | 659 | } |
40bee44e | 660 | EXPORT_SYMBOL(__splice_from_pipe); |
5274f052 | 661 | |
932cc6d4 JA |
662 | /** |
663 | * splice_from_pipe - splice data from a pipe to a file | |
664 | * @pipe: pipe to splice from | |
665 | * @out: file to splice to | |
666 | * @ppos: position in @out | |
667 | * @len: how many bytes to splice | |
668 | * @flags: splice modifier flags | |
669 | * @actor: handler that splices the data | |
670 | * | |
671 | * Description: | |
2933970b | 672 | * See __splice_from_pipe. This function locks the pipe inode, |
932cc6d4 JA |
673 | * otherwise it's identical to __splice_from_pipe(). |
674 | * | |
675 | */ | |
6da61809 MF |
676 | ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
677 | loff_t *ppos, size_t len, unsigned int flags, | |
678 | splice_actor *actor) | |
679 | { | |
680 | ssize_t ret; | |
c66ab6fa JA |
681 | struct splice_desc sd = { |
682 | .total_len = len, | |
683 | .flags = flags, | |
684 | .pos = *ppos, | |
6a14b90b | 685 | .u.file = out, |
c66ab6fa | 686 | }; |
6da61809 | 687 | |
61e0d47c | 688 | pipe_lock(pipe); |
c66ab6fa | 689 | ret = __splice_from_pipe(pipe, &sd, actor); |
61e0d47c | 690 | pipe_unlock(pipe); |
6da61809 MF |
691 | |
692 | return ret; | |
693 | } | |
694 | ||
8d020765 AV |
695 | /** |
696 | * iter_file_splice_write - splice data from a pipe to a file | |
697 | * @pipe: pipe info | |
698 | * @out: file to write to | |
699 | * @ppos: position in @out | |
700 | * @len: number of bytes to splice | |
701 | * @flags: splice modifier flags | |
702 | * | |
703 | * Description: | |
704 | * Will either move or copy pages (determined by @flags options) from | |
705 | * the given pipe inode to the given file. | |
706 | * This one is ->write_iter-based. | |
707 | * | |
708 | */ | |
709 | ssize_t | |
710 | iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, | |
711 | loff_t *ppos, size_t len, unsigned int flags) | |
712 | { | |
713 | struct splice_desc sd = { | |
714 | .total_len = len, | |
715 | .flags = flags, | |
716 | .pos = *ppos, | |
717 | .u.file = out, | |
718 | }; | |
719 | int nbufs = pipe->buffers; | |
720 | struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), | |
721 | GFP_KERNEL); | |
722 | ssize_t ret; | |
723 | ||
724 | if (unlikely(!array)) | |
725 | return -ENOMEM; | |
726 | ||
727 | pipe_lock(pipe); | |
728 | ||
729 | splice_from_pipe_begin(&sd); | |
730 | while (sd.total_len) { | |
731 | struct iov_iter from; | |
8d020765 AV |
732 | size_t left; |
733 | int n, idx; | |
734 | ||
735 | ret = splice_from_pipe_next(pipe, &sd); | |
736 | if (ret <= 0) | |
737 | break; | |
738 | ||
739 | if (unlikely(nbufs < pipe->buffers)) { | |
740 | kfree(array); | |
741 | nbufs = pipe->buffers; | |
742 | array = kcalloc(nbufs, sizeof(struct bio_vec), | |
743 | GFP_KERNEL); | |
744 | if (!array) { | |
745 | ret = -ENOMEM; | |
746 | break; | |
747 | } | |
748 | } | |
749 | ||
750 | /* build the vector */ | |
751 | left = sd.total_len; | |
752 | for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) { | |
753 | struct pipe_buffer *buf = pipe->bufs + idx; | |
754 | size_t this_len = buf->len; | |
755 | ||
756 | if (this_len > left) | |
757 | this_len = left; | |
758 | ||
759 | if (idx == pipe->buffers - 1) | |
760 | idx = -1; | |
761 | ||
762 | ret = buf->ops->confirm(pipe, buf); | |
763 | if (unlikely(ret)) { | |
764 | if (ret == -ENODATA) | |
765 | ret = 0; | |
766 | goto done; | |
767 | } | |
768 | ||
769 | array[n].bv_page = buf->page; | |
770 | array[n].bv_len = this_len; | |
771 | array[n].bv_offset = buf->offset; | |
772 | left -= this_len; | |
773 | } | |
774 | ||
05afcb77 AV |
775 | iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n, |
776 | sd.total_len - left); | |
dbe4e192 | 777 | ret = vfs_iter_write(out, &from, &sd.pos); |
8d020765 AV |
778 | if (ret <= 0) |
779 | break; | |
780 | ||
781 | sd.num_spliced += ret; | |
782 | sd.total_len -= ret; | |
dbe4e192 | 783 | *ppos = sd.pos; |
8d020765 AV |
784 | |
785 | /* dismiss the fully eaten buffers, adjust the partial one */ | |
786 | while (ret) { | |
787 | struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; | |
788 | if (ret >= buf->len) { | |
8d020765 AV |
789 | ret -= buf->len; |
790 | buf->len = 0; | |
a779638c | 791 | pipe_buf_release(pipe, buf); |
8d020765 AV |
792 | pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); |
793 | pipe->nrbufs--; | |
794 | if (pipe->files) | |
795 | sd.need_wakeup = true; | |
796 | } else { | |
797 | buf->offset += ret; | |
798 | buf->len -= ret; | |
799 | ret = 0; | |
800 | } | |
801 | } | |
802 | } | |
803 | done: | |
804 | kfree(array); | |
805 | splice_from_pipe_end(pipe, &sd); | |
806 | ||
807 | pipe_unlock(pipe); | |
808 | ||
809 | if (sd.num_spliced) | |
810 | ret = sd.num_spliced; | |
811 | ||
812 | return ret; | |
813 | } | |
814 | ||
815 | EXPORT_SYMBOL(iter_file_splice_write); | |
816 | ||
b2858d7d MS |
817 | static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
818 | struct splice_desc *sd) | |
0b0a47f5 | 819 | { |
b2858d7d MS |
820 | int ret; |
821 | void *data; | |
06ae43f3 | 822 | loff_t tmp = sd->pos; |
b2858d7d | 823 | |
fbb32750 | 824 | data = kmap(buf->page); |
06ae43f3 | 825 | ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp); |
fbb32750 | 826 | kunmap(buf->page); |
b2858d7d MS |
827 | |
828 | return ret; | |
0b0a47f5 MS |
829 | } |
830 | ||
831 | static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, | |
832 | struct file *out, loff_t *ppos, | |
833 | size_t len, unsigned int flags) | |
834 | { | |
b2858d7d | 835 | ssize_t ret; |
0b0a47f5 | 836 | |
b2858d7d MS |
837 | ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf); |
838 | if (ret > 0) | |
839 | *ppos += ret; | |
0b0a47f5 | 840 | |
b2858d7d | 841 | return ret; |
0b0a47f5 MS |
842 | } |
843 | ||
83f9135b JA |
844 | /** |
845 | * generic_splice_sendpage - splice data from a pipe to a socket | |
932cc6d4 | 846 | * @pipe: pipe to splice from |
83f9135b | 847 | * @out: socket to write to |
932cc6d4 | 848 | * @ppos: position in @out |
83f9135b JA |
849 | * @len: number of bytes to splice |
850 | * @flags: splice modifier flags | |
851 | * | |
932cc6d4 JA |
852 | * Description: |
853 | * Will send @len bytes from the pipe to a network socket. No data copying | |
854 | * is involved. | |
83f9135b JA |
855 | * |
856 | */ | |
3a326a2c | 857 | ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 858 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 859 | { |
00522fb4 | 860 | return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); |
5274f052 JA |
861 | } |
862 | ||
059a8f37 | 863 | EXPORT_SYMBOL(generic_splice_sendpage); |
a0f06780 | 864 | |
83f9135b JA |
865 | /* |
866 | * Attempt to initiate a splice from pipe to file. | |
867 | */ | |
3a326a2c | 868 | static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
cbb7e577 | 869 | loff_t *ppos, size_t len, unsigned int flags) |
5274f052 | 870 | { |
0b0a47f5 MS |
871 | ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, |
872 | loff_t *, size_t, unsigned int); | |
5274f052 | 873 | |
72c2d531 | 874 | if (out->f_op->splice_write) |
cc56f7de CG |
875 | splice_write = out->f_op->splice_write; |
876 | else | |
0b0a47f5 MS |
877 | splice_write = default_file_splice_write; |
878 | ||
500368f7 | 879 | return splice_write(pipe, out, ppos, len, flags); |
5274f052 JA |
880 | } |
881 | ||
83f9135b JA |
882 | /* |
883 | * Attempt to initiate a splice from a file to a pipe. | |
884 | */ | |
cbb7e577 JA |
885 | static long do_splice_to(struct file *in, loff_t *ppos, |
886 | struct pipe_inode_info *pipe, size_t len, | |
887 | unsigned int flags) | |
5274f052 | 888 | { |
6818173b MS |
889 | ssize_t (*splice_read)(struct file *, loff_t *, |
890 | struct pipe_inode_info *, size_t, unsigned int); | |
5274f052 JA |
891 | int ret; |
892 | ||
49570e9b | 893 | if (unlikely(!(in->f_mode & FMODE_READ))) |
5274f052 JA |
894 | return -EBADF; |
895 | ||
cbb7e577 | 896 | ret = rw_verify_area(READ, in, ppos, len); |
5274f052 JA |
897 | if (unlikely(ret < 0)) |
898 | return ret; | |
899 | ||
03cc0789 AV |
900 | if (unlikely(len > MAX_RW_COUNT)) |
901 | len = MAX_RW_COUNT; | |
902 | ||
72c2d531 | 903 | if (in->f_op->splice_read) |
cc56f7de CG |
904 | splice_read = in->f_op->splice_read; |
905 | else | |
6818173b MS |
906 | splice_read = default_file_splice_read; |
907 | ||
908 | return splice_read(in, ppos, pipe, len, flags); | |
5274f052 JA |
909 | } |
910 | ||
932cc6d4 JA |
911 | /** |
912 | * splice_direct_to_actor - splices data directly between two non-pipes | |
913 | * @in: file to splice from | |
914 | * @sd: actor information on where to splice to | |
915 | * @actor: handles the data splicing | |
916 | * | |
917 | * Description: | |
918 | * This is a special case helper to splice directly between two | |
919 | * points, without requiring an explicit pipe. Internally an allocated | |
79685b8d | 920 | * pipe is cached in the process, and reused during the lifetime of |
932cc6d4 JA |
921 | * that process. |
922 | * | |
c66ab6fa JA |
923 | */ |
924 | ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, | |
925 | splice_direct_actor *actor) | |
b92ce558 JA |
926 | { |
927 | struct pipe_inode_info *pipe; | |
928 | long ret, bytes; | |
929 | umode_t i_mode; | |
c66ab6fa | 930 | size_t len; |
0ff28d9f | 931 | int i, flags, more; |
b92ce558 JA |
932 | |
933 | /* | |
934 | * We require the input being a regular file, as we don't want to | |
935 | * randomly drop data for eg socket -> socket splicing. Use the | |
936 | * piped splicing for that! | |
937 | */ | |
496ad9aa | 938 | i_mode = file_inode(in)->i_mode; |
b92ce558 JA |
939 | if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
940 | return -EINVAL; | |
941 | ||
942 | /* | |
943 | * neither in nor out is a pipe, setup an internal pipe attached to | |
944 | * 'out' and transfer the wanted data from 'in' to 'out' through that | |
945 | */ | |
946 | pipe = current->splice_pipe; | |
49570e9b | 947 | if (unlikely(!pipe)) { |
7bee130e | 948 | pipe = alloc_pipe_info(); |
b92ce558 JA |
949 | if (!pipe) |
950 | return -ENOMEM; | |
951 | ||
952 | /* | |
953 | * We don't have an immediate reader, but we'll read the stuff | |
00522fb4 | 954 | * out of the pipe right after the splice_to_pipe(). So set |
b92ce558 JA |
955 | * PIPE_READERS appropriately. |
956 | */ | |
957 | pipe->readers = 1; | |
958 | ||
959 | current->splice_pipe = pipe; | |
960 | } | |
961 | ||
962 | /* | |
73d62d83 | 963 | * Do the splice. |
b92ce558 JA |
964 | */ |
965 | ret = 0; | |
966 | bytes = 0; | |
c66ab6fa JA |
967 | len = sd->total_len; |
968 | flags = sd->flags; | |
969 | ||
970 | /* | |
971 | * Don't block on output, we have to drain the direct pipe. | |
972 | */ | |
973 | sd->flags &= ~SPLICE_F_NONBLOCK; | |
0ff28d9f | 974 | more = sd->flags & SPLICE_F_MORE; |
b92ce558 JA |
975 | |
976 | while (len) { | |
51a92c0f | 977 | size_t read_len; |
a82c53a0 | 978 | loff_t pos = sd->pos, prev_pos = pos; |
b92ce558 | 979 | |
bcd4f3ac | 980 | ret = do_splice_to(in, &pos, pipe, len, flags); |
51a92c0f | 981 | if (unlikely(ret <= 0)) |
b92ce558 JA |
982 | goto out_release; |
983 | ||
984 | read_len = ret; | |
c66ab6fa | 985 | sd->total_len = read_len; |
b92ce558 | 986 | |
0ff28d9f CL |
987 | /* |
988 | * If more data is pending, set SPLICE_F_MORE | |
989 | * If this is the last data and SPLICE_F_MORE was not set | |
990 | * initially, clears it. | |
991 | */ | |
992 | if (read_len < len) | |
993 | sd->flags |= SPLICE_F_MORE; | |
994 | else if (!more) | |
995 | sd->flags &= ~SPLICE_F_MORE; | |
b92ce558 JA |
996 | /* |
997 | * NOTE: nonblocking mode only applies to the input. We | |
998 | * must not do the output in nonblocking mode as then we | |
999 | * could get stuck data in the internal pipe: | |
1000 | */ | |
c66ab6fa | 1001 | ret = actor(pipe, sd); |
a82c53a0 TZ |
1002 | if (unlikely(ret <= 0)) { |
1003 | sd->pos = prev_pos; | |
b92ce558 | 1004 | goto out_release; |
a82c53a0 | 1005 | } |
b92ce558 JA |
1006 | |
1007 | bytes += ret; | |
1008 | len -= ret; | |
bcd4f3ac | 1009 | sd->pos = pos; |
b92ce558 | 1010 | |
a82c53a0 TZ |
1011 | if (ret < read_len) { |
1012 | sd->pos = prev_pos + ret; | |
51a92c0f | 1013 | goto out_release; |
a82c53a0 | 1014 | } |
b92ce558 JA |
1015 | } |
1016 | ||
9e97198d | 1017 | done: |
b92ce558 | 1018 | pipe->nrbufs = pipe->curbuf = 0; |
80848708 | 1019 | file_accessed(in); |
b92ce558 JA |
1020 | return bytes; |
1021 | ||
1022 | out_release: | |
1023 | /* | |
1024 | * If we did an incomplete transfer we must release | |
1025 | * the pipe buffers in question: | |
1026 | */ | |
35f3d14d | 1027 | for (i = 0; i < pipe->buffers; i++) { |
b92ce558 JA |
1028 | struct pipe_buffer *buf = pipe->bufs + i; |
1029 | ||
a779638c MS |
1030 | if (buf->ops) |
1031 | pipe_buf_release(pipe, buf); | |
b92ce558 | 1032 | } |
b92ce558 | 1033 | |
9e97198d JA |
1034 | if (!bytes) |
1035 | bytes = ret; | |
c66ab6fa | 1036 | |
9e97198d | 1037 | goto done; |
c66ab6fa JA |
1038 | } |
1039 | EXPORT_SYMBOL(splice_direct_to_actor); | |
1040 | ||
1041 | static int direct_splice_actor(struct pipe_inode_info *pipe, | |
1042 | struct splice_desc *sd) | |
1043 | { | |
6a14b90b | 1044 | struct file *file = sd->u.file; |
c66ab6fa | 1045 | |
7995bd28 | 1046 | return do_splice_from(pipe, file, sd->opos, sd->total_len, |
2cb4b05e | 1047 | sd->flags); |
c66ab6fa JA |
1048 | } |
1049 | ||
932cc6d4 JA |
1050 | /** |
1051 | * do_splice_direct - splices data directly between two files | |
1052 | * @in: file to splice from | |
1053 | * @ppos: input file offset | |
1054 | * @out: file to splice to | |
acdb37c3 | 1055 | * @opos: output file offset |
932cc6d4 JA |
1056 | * @len: number of bytes to splice |
1057 | * @flags: splice modifier flags | |
1058 | * | |
1059 | * Description: | |
1060 | * For use by do_sendfile(). splice can easily emulate sendfile, but | |
1061 | * doing it in the application would incur an extra system call | |
1062 | * (splice in + splice out, as compared to just sendfile()). So this helper | |
1063 | * can splice directly through a process-private pipe. | |
1064 | * | |
1065 | */ | |
c66ab6fa | 1066 | long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
7995bd28 | 1067 | loff_t *opos, size_t len, unsigned int flags) |
c66ab6fa JA |
1068 | { |
1069 | struct splice_desc sd = { | |
1070 | .len = len, | |
1071 | .total_len = len, | |
1072 | .flags = flags, | |
1073 | .pos = *ppos, | |
6a14b90b | 1074 | .u.file = out, |
7995bd28 | 1075 | .opos = opos, |
c66ab6fa | 1076 | }; |
51a92c0f | 1077 | long ret; |
c66ab6fa | 1078 | |
18c67cb9 AV |
1079 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1080 | return -EBADF; | |
1081 | ||
1082 | if (unlikely(out->f_flags & O_APPEND)) | |
1083 | return -EINVAL; | |
1084 | ||
1085 | ret = rw_verify_area(WRITE, out, opos, len); | |
1086 | if (unlikely(ret < 0)) | |
1087 | return ret; | |
1088 | ||
c66ab6fa | 1089 | ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
51a92c0f | 1090 | if (ret > 0) |
a82c53a0 | 1091 | *ppos = sd.pos; |
51a92c0f | 1092 | |
c66ab6fa | 1093 | return ret; |
b92ce558 | 1094 | } |
1c118596 | 1095 | EXPORT_SYMBOL(do_splice_direct); |
b92ce558 | 1096 | |
8924feff AV |
1097 | static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) |
1098 | { | |
1099 | while (pipe->nrbufs == pipe->buffers) { | |
1100 | if (flags & SPLICE_F_NONBLOCK) | |
1101 | return -EAGAIN; | |
1102 | if (signal_pending(current)) | |
1103 | return -ERESTARTSYS; | |
1104 | pipe->waiting_writers++; | |
1105 | pipe_wait(pipe); | |
1106 | pipe->waiting_writers--; | |
1107 | } | |
1108 | return 0; | |
1109 | } | |
1110 | ||
7c77f0b3 MS |
1111 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
1112 | struct pipe_inode_info *opipe, | |
1113 | size_t len, unsigned int flags); | |
ddac0d39 | 1114 | |
83f9135b JA |
1115 | /* |
1116 | * Determine where to splice to/from. | |
1117 | */ | |
529565dc IM |
1118 | static long do_splice(struct file *in, loff_t __user *off_in, |
1119 | struct file *out, loff_t __user *off_out, | |
1120 | 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 | |
71993e62 LT |
1127 | ipipe = get_pipe_info(in); |
1128 | opipe = get_pipe_info(out); | |
7c77f0b3 MS |
1129 | |
1130 | if (ipipe && opipe) { | |
1131 | if (off_in || off_out) | |
1132 | return -ESPIPE; | |
1133 | ||
1134 | if (!(in->f_mode & FMODE_READ)) | |
1135 | return -EBADF; | |
1136 | ||
1137 | if (!(out->f_mode & FMODE_WRITE)) | |
1138 | return -EBADF; | |
1139 | ||
1140 | /* Splicing to self would be fun, but... */ | |
1141 | if (ipipe == opipe) | |
1142 | return -EINVAL; | |
1143 | ||
1144 | return splice_pipe_to_pipe(ipipe, opipe, len, flags); | |
1145 | } | |
1146 | ||
1147 | if (ipipe) { | |
529565dc IM |
1148 | if (off_in) |
1149 | return -ESPIPE; | |
b92ce558 | 1150 | if (off_out) { |
19c9a49b | 1151 | if (!(out->f_mode & FMODE_PWRITE)) |
b92ce558 | 1152 | return -EINVAL; |
cbb7e577 | 1153 | if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
b92ce558 | 1154 | return -EFAULT; |
7995bd28 AV |
1155 | } else { |
1156 | offset = out->f_pos; | |
1157 | } | |
529565dc | 1158 | |
18c67cb9 AV |
1159 | if (unlikely(!(out->f_mode & FMODE_WRITE))) |
1160 | return -EBADF; | |
1161 | ||
1162 | if (unlikely(out->f_flags & O_APPEND)) | |
1163 | return -EINVAL; | |
1164 | ||
1165 | ret = rw_verify_area(WRITE, out, &offset, len); | |
1166 | if (unlikely(ret < 0)) | |
1167 | return ret; | |
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 | |
7995bd28 AV |
1173 | if (!off_out) |
1174 | out->f_pos = offset; | |
1175 | else if (copy_to_user(off_out, &offset, sizeof(loff_t))) | |
a4514ebd JA |
1176 | ret = -EFAULT; |
1177 | ||
1178 | return ret; | |
529565dc | 1179 | } |
5274f052 | 1180 | |
7c77f0b3 | 1181 | if (opipe) { |
529565dc IM |
1182 | if (off_out) |
1183 | return -ESPIPE; | |
b92ce558 | 1184 | if (off_in) { |
19c9a49b | 1185 | if (!(in->f_mode & FMODE_PREAD)) |
b92ce558 | 1186 | return -EINVAL; |
cbb7e577 | 1187 | if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
b92ce558 | 1188 | return -EFAULT; |
7995bd28 AV |
1189 | } else { |
1190 | offset = in->f_pos; | |
1191 | } | |
529565dc | 1192 | |
8924feff AV |
1193 | pipe_lock(opipe); |
1194 | ret = wait_for_space(opipe, flags); | |
1195 | if (!ret) | |
1196 | ret = do_splice_to(in, &offset, opipe, len, flags); | |
1197 | pipe_unlock(opipe); | |
1198 | if (ret > 0) | |
1199 | wakeup_pipe_readers(opipe); | |
7995bd28 AV |
1200 | if (!off_in) |
1201 | in->f_pos = offset; | |
1202 | else if (copy_to_user(off_in, &offset, sizeof(loff_t))) | |
a4514ebd JA |
1203 | ret = -EFAULT; |
1204 | ||
1205 | return ret; | |
529565dc | 1206 | } |
5274f052 JA |
1207 | |
1208 | return -EINVAL; | |
1209 | } | |
1210 | ||
79fddc4e AV |
1211 | static int iter_to_pipe(struct iov_iter *from, |
1212 | struct pipe_inode_info *pipe, | |
1213 | unsigned flags) | |
912d35f8 | 1214 | { |
79fddc4e AV |
1215 | struct pipe_buffer buf = { |
1216 | .ops = &user_page_pipe_buf_ops, | |
1217 | .flags = flags | |
1218 | }; | |
1219 | size_t total = 0; | |
1220 | int ret = 0; | |
1221 | bool failed = false; | |
1222 | ||
1223 | while (iov_iter_count(from) && !failed) { | |
1224 | struct page *pages[16]; | |
db85a9eb AV |
1225 | ssize_t copied; |
1226 | size_t start; | |
79fddc4e | 1227 | int n; |
db85a9eb | 1228 | |
79fddc4e AV |
1229 | copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start); |
1230 | if (copied <= 0) { | |
1231 | ret = copied; | |
1232 | break; | |
1233 | } | |
db85a9eb | 1234 | |
79fddc4e | 1235 | for (n = 0; copied; n++, start = 0) { |
db85a9eb | 1236 | int size = min_t(int, copied, PAGE_SIZE - start); |
79fddc4e AV |
1237 | if (!failed) { |
1238 | buf.page = pages[n]; | |
1239 | buf.offset = start; | |
1240 | buf.len = size; | |
1241 | ret = add_to_pipe(pipe, &buf); | |
1242 | if (unlikely(ret < 0)) { | |
1243 | failed = true; | |
1244 | } else { | |
1245 | iov_iter_advance(from, ret); | |
1246 | total += ret; | |
1247 | } | |
1248 | } else { | |
1249 | put_page(pages[n]); | |
1250 | } | |
db85a9eb | 1251 | copied -= size; |
912d35f8 | 1252 | } |
912d35f8 | 1253 | } |
79fddc4e | 1254 | return total ? total : ret; |
912d35f8 JA |
1255 | } |
1256 | ||
6a14b90b JA |
1257 | static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
1258 | struct splice_desc *sd) | |
1259 | { | |
6130f531 AV |
1260 | int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
1261 | return n == sd->len ? n : -EFAULT; | |
6a14b90b JA |
1262 | } |
1263 | ||
1264 | /* | |
1265 | * For lack of a better implementation, implement vmsplice() to userspace | |
1266 | * as a simple copy of the pipes pages to the user iov. | |
1267 | */ | |
6130f531 | 1268 | static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov, |
6a14b90b JA |
1269 | unsigned long nr_segs, unsigned int flags) |
1270 | { | |
1271 | struct pipe_inode_info *pipe; | |
1272 | struct splice_desc sd; | |
6a14b90b | 1273 | long ret; |
6130f531 AV |
1274 | struct iovec iovstack[UIO_FASTIOV]; |
1275 | struct iovec *iov = iovstack; | |
1276 | struct iov_iter iter; | |
6a14b90b | 1277 | |
71993e62 | 1278 | pipe = get_pipe_info(file); |
6a14b90b JA |
1279 | if (!pipe) |
1280 | return -EBADF; | |
1281 | ||
345995fa AV |
1282 | ret = import_iovec(READ, uiov, nr_segs, |
1283 | ARRAY_SIZE(iovstack), &iov, &iter); | |
1284 | if (ret < 0) | |
1285 | return ret; | |
6a14b90b | 1286 | |
345995fa | 1287 | sd.total_len = iov_iter_count(&iter); |
6130f531 | 1288 | sd.len = 0; |
6130f531 AV |
1289 | sd.flags = flags; |
1290 | sd.u.data = &iter; | |
1291 | sd.pos = 0; | |
6a14b90b | 1292 | |
345995fa AV |
1293 | if (sd.total_len) { |
1294 | pipe_lock(pipe); | |
1295 | ret = __splice_from_pipe(pipe, &sd, pipe_to_user); | |
1296 | pipe_unlock(pipe); | |
1297 | } | |
6a14b90b | 1298 | |
345995fa | 1299 | kfree(iov); |
6a14b90b JA |
1300 | return ret; |
1301 | } | |
1302 | ||
912d35f8 JA |
1303 | /* |
1304 | * vmsplice splices a user address range into a pipe. It can be thought of | |
1305 | * as splice-from-memory, where the regular splice is splice-from-file (or | |
1306 | * to file). In both cases the output is a pipe, naturally. | |
912d35f8 | 1307 | */ |
db85a9eb | 1308 | static long vmsplice_to_pipe(struct file *file, const struct iovec __user *uiov, |
6a14b90b | 1309 | unsigned long nr_segs, unsigned int flags) |
912d35f8 | 1310 | { |
ddac0d39 | 1311 | struct pipe_inode_info *pipe; |
db85a9eb AV |
1312 | struct iovec iovstack[UIO_FASTIOV]; |
1313 | struct iovec *iov = iovstack; | |
1314 | struct iov_iter from; | |
35f3d14d | 1315 | long ret; |
79fddc4e AV |
1316 | unsigned buf_flag = 0; |
1317 | ||
1318 | if (flags & SPLICE_F_GIFT) | |
1319 | buf_flag = PIPE_BUF_FLAG_GIFT; | |
912d35f8 | 1320 | |
71993e62 | 1321 | pipe = get_pipe_info(file); |
ddac0d39 | 1322 | if (!pipe) |
912d35f8 | 1323 | return -EBADF; |
912d35f8 | 1324 | |
db85a9eb AV |
1325 | ret = import_iovec(WRITE, uiov, nr_segs, |
1326 | ARRAY_SIZE(iovstack), &iov, &from); | |
1327 | if (ret < 0) | |
1328 | return ret; | |
1329 | ||
8924feff AV |
1330 | pipe_lock(pipe); |
1331 | ret = wait_for_space(pipe, flags); | |
79fddc4e AV |
1332 | if (!ret) |
1333 | ret = iter_to_pipe(&from, pipe, buf_flag); | |
8924feff AV |
1334 | pipe_unlock(pipe); |
1335 | if (ret > 0) | |
1336 | wakeup_pipe_readers(pipe); | |
db85a9eb | 1337 | kfree(iov); |
35f3d14d | 1338 | return ret; |
912d35f8 JA |
1339 | } |
1340 | ||
6a14b90b JA |
1341 | /* |
1342 | * Note that vmsplice only really supports true splicing _from_ user memory | |
1343 | * to a pipe, not the other way around. Splicing from user memory is a simple | |
1344 | * operation that can be supported without any funky alignment restrictions | |
1345 | * or nasty vm tricks. We simply map in the user memory and fill them into | |
1346 | * a pipe. The reverse isn't quite as easy, though. There are two possible | |
1347 | * solutions for that: | |
1348 | * | |
1349 | * - memcpy() the data internally, at which point we might as well just | |
1350 | * do a regular read() on the buffer anyway. | |
1351 | * - Lots of nasty vm tricks, that are neither fast nor flexible (it | |
1352 | * has restriction limitations on both ends of the pipe). | |
1353 | * | |
1354 | * Currently we punt and implement it as a normal copy, see pipe_to_user(). | |
1355 | * | |
1356 | */ | |
836f92ad HC |
1357 | SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov, |
1358 | unsigned long, nr_segs, unsigned int, flags) | |
912d35f8 | 1359 | { |
2903ff01 | 1360 | struct fd f; |
912d35f8 | 1361 | long error; |
912d35f8 | 1362 | |
6a14b90b JA |
1363 | if (unlikely(nr_segs > UIO_MAXIOV)) |
1364 | return -EINVAL; | |
1365 | else if (unlikely(!nr_segs)) | |
1366 | return 0; | |
1367 | ||
912d35f8 | 1368 | error = -EBADF; |
2903ff01 AV |
1369 | f = fdget(fd); |
1370 | if (f.file) { | |
1371 | if (f.file->f_mode & FMODE_WRITE) | |
1372 | error = vmsplice_to_pipe(f.file, iov, nr_segs, flags); | |
1373 | else if (f.file->f_mode & FMODE_READ) | |
1374 | error = vmsplice_to_user(f.file, iov, nr_segs, flags); | |
1375 | ||
1376 | fdput(f); | |
912d35f8 JA |
1377 | } |
1378 | ||
1379 | return error; | |
1380 | } | |
1381 | ||
76b021d0 AV |
1382 | #ifdef CONFIG_COMPAT |
1383 | COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32, | |
1384 | unsigned int, nr_segs, unsigned int, flags) | |
1385 | { | |
1386 | unsigned i; | |
1387 | struct iovec __user *iov; | |
1388 | if (nr_segs > UIO_MAXIOV) | |
1389 | return -EINVAL; | |
1390 | iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec)); | |
1391 | for (i = 0; i < nr_segs; i++) { | |
1392 | struct compat_iovec v; | |
1393 | if (get_user(v.iov_base, &iov32[i].iov_base) || | |
1394 | get_user(v.iov_len, &iov32[i].iov_len) || | |
1395 | put_user(compat_ptr(v.iov_base), &iov[i].iov_base) || | |
1396 | put_user(v.iov_len, &iov[i].iov_len)) | |
1397 | return -EFAULT; | |
1398 | } | |
1399 | return sys_vmsplice(fd, iov, nr_segs, flags); | |
1400 | } | |
1401 | #endif | |
1402 | ||
836f92ad HC |
1403 | SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, |
1404 | int, fd_out, loff_t __user *, off_out, | |
1405 | size_t, len, unsigned int, flags) | |
5274f052 | 1406 | { |
2903ff01 | 1407 | struct fd in, out; |
5274f052 | 1408 | long error; |
5274f052 JA |
1409 | |
1410 | if (unlikely(!len)) | |
1411 | return 0; | |
1412 | ||
1413 | error = -EBADF; | |
2903ff01 AV |
1414 | in = fdget(fd_in); |
1415 | if (in.file) { | |
1416 | if (in.file->f_mode & FMODE_READ) { | |
1417 | out = fdget(fd_out); | |
1418 | if (out.file) { | |
1419 | if (out.file->f_mode & FMODE_WRITE) | |
1420 | error = do_splice(in.file, off_in, | |
1421 | out.file, off_out, | |
529565dc | 1422 | len, flags); |
2903ff01 | 1423 | fdput(out); |
5274f052 JA |
1424 | } |
1425 | } | |
2903ff01 | 1426 | fdput(in); |
5274f052 | 1427 | } |
5274f052 JA |
1428 | return error; |
1429 | } | |
70524490 | 1430 | |
aadd06e5 JA |
1431 | /* |
1432 | * Make sure there's data to read. Wait for input if we can, otherwise | |
1433 | * return an appropriate error. | |
1434 | */ | |
7c77f0b3 | 1435 | static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1436 | { |
1437 | int ret; | |
1438 | ||
1439 | /* | |
1440 | * Check ->nrbufs without the inode lock first. This function | |
1441 | * is speculative anyways, so missing one is ok. | |
1442 | */ | |
1443 | if (pipe->nrbufs) | |
1444 | return 0; | |
1445 | ||
1446 | ret = 0; | |
61e0d47c | 1447 | pipe_lock(pipe); |
aadd06e5 JA |
1448 | |
1449 | while (!pipe->nrbufs) { | |
1450 | if (signal_pending(current)) { | |
1451 | ret = -ERESTARTSYS; | |
1452 | break; | |
1453 | } | |
1454 | if (!pipe->writers) | |
1455 | break; | |
1456 | if (!pipe->waiting_writers) { | |
1457 | if (flags & SPLICE_F_NONBLOCK) { | |
1458 | ret = -EAGAIN; | |
1459 | break; | |
1460 | } | |
1461 | } | |
1462 | pipe_wait(pipe); | |
1463 | } | |
1464 | ||
61e0d47c | 1465 | pipe_unlock(pipe); |
aadd06e5 JA |
1466 | return ret; |
1467 | } | |
1468 | ||
1469 | /* | |
1470 | * Make sure there's writeable room. Wait for room if we can, otherwise | |
1471 | * return an appropriate error. | |
1472 | */ | |
7c77f0b3 | 1473 | static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
aadd06e5 JA |
1474 | { |
1475 | int ret; | |
1476 | ||
1477 | /* | |
1478 | * Check ->nrbufs without the inode lock first. This function | |
1479 | * is speculative anyways, so missing one is ok. | |
1480 | */ | |
35f3d14d | 1481 | if (pipe->nrbufs < pipe->buffers) |
aadd06e5 JA |
1482 | return 0; |
1483 | ||
1484 | ret = 0; | |
61e0d47c | 1485 | pipe_lock(pipe); |
aadd06e5 | 1486 | |
35f3d14d | 1487 | while (pipe->nrbufs >= pipe->buffers) { |
aadd06e5 JA |
1488 | if (!pipe->readers) { |
1489 | send_sig(SIGPIPE, current, 0); | |
1490 | ret = -EPIPE; | |
1491 | break; | |
1492 | } | |
1493 | if (flags & SPLICE_F_NONBLOCK) { | |
1494 | ret = -EAGAIN; | |
1495 | break; | |
1496 | } | |
1497 | if (signal_pending(current)) { | |
1498 | ret = -ERESTARTSYS; | |
1499 | break; | |
1500 | } | |
1501 | pipe->waiting_writers++; | |
1502 | pipe_wait(pipe); | |
1503 | pipe->waiting_writers--; | |
1504 | } | |
1505 | ||
61e0d47c | 1506 | pipe_unlock(pipe); |
aadd06e5 JA |
1507 | return ret; |
1508 | } | |
1509 | ||
7c77f0b3 MS |
1510 | /* |
1511 | * Splice contents of ipipe to opipe. | |
1512 | */ | |
1513 | static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, | |
1514 | struct pipe_inode_info *opipe, | |
1515 | size_t len, unsigned int flags) | |
1516 | { | |
1517 | struct pipe_buffer *ibuf, *obuf; | |
1518 | int ret = 0, nbuf; | |
1519 | bool input_wakeup = false; | |
1520 | ||
1521 | ||
1522 | retry: | |
1523 | ret = ipipe_prep(ipipe, flags); | |
1524 | if (ret) | |
1525 | return ret; | |
1526 | ||
1527 | ret = opipe_prep(opipe, flags); | |
1528 | if (ret) | |
1529 | return ret; | |
1530 | ||
1531 | /* | |
1532 | * Potential ABBA deadlock, work around it by ordering lock | |
1533 | * grabbing by pipe info address. Otherwise two different processes | |
1534 | * could deadlock (one doing tee from A -> B, the other from B -> A). | |
1535 | */ | |
1536 | pipe_double_lock(ipipe, opipe); | |
1537 | ||
1538 | do { | |
1539 | if (!opipe->readers) { | |
1540 | send_sig(SIGPIPE, current, 0); | |
1541 | if (!ret) | |
1542 | ret = -EPIPE; | |
1543 | break; | |
1544 | } | |
1545 | ||
1546 | if (!ipipe->nrbufs && !ipipe->writers) | |
1547 | break; | |
1548 | ||
1549 | /* | |
1550 | * Cannot make any progress, because either the input | |
1551 | * pipe is empty or the output pipe is full. | |
1552 | */ | |
35f3d14d | 1553 | if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { |
7c77f0b3 MS |
1554 | /* Already processed some buffers, break */ |
1555 | if (ret) | |
1556 | break; | |
1557 | ||
1558 | if (flags & SPLICE_F_NONBLOCK) { | |
1559 | ret = -EAGAIN; | |
1560 | break; | |
1561 | } | |
1562 | ||
1563 | /* | |
1564 | * We raced with another reader/writer and haven't | |
1565 | * managed to process any buffers. A zero return | |
1566 | * value means EOF, so retry instead. | |
1567 | */ | |
1568 | pipe_unlock(ipipe); | |
1569 | pipe_unlock(opipe); | |
1570 | goto retry; | |
1571 | } | |
1572 | ||
1573 | ibuf = ipipe->bufs + ipipe->curbuf; | |
35f3d14d | 1574 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); |
7c77f0b3 MS |
1575 | obuf = opipe->bufs + nbuf; |
1576 | ||
1577 | if (len >= ibuf->len) { | |
1578 | /* | |
1579 | * Simply move the whole buffer from ipipe to opipe | |
1580 | */ | |
1581 | *obuf = *ibuf; | |
1582 | ibuf->ops = NULL; | |
1583 | opipe->nrbufs++; | |
35f3d14d | 1584 | ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); |
7c77f0b3 MS |
1585 | ipipe->nrbufs--; |
1586 | input_wakeup = true; | |
1587 | } else { | |
1588 | /* | |
1589 | * Get a reference to this pipe buffer, | |
1590 | * so we can copy the contents over. | |
1591 | */ | |
7bf2d1df | 1592 | pipe_buf_get(ipipe, ibuf); |
7c77f0b3 MS |
1593 | *obuf = *ibuf; |
1594 | ||
1595 | /* | |
1596 | * Don't inherit the gift flag, we need to | |
1597 | * prevent multiple steals of this page. | |
1598 | */ | |
1599 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; | |
1600 | ||
1601 | obuf->len = len; | |
1602 | opipe->nrbufs++; | |
1603 | ibuf->offset += obuf->len; | |
1604 | ibuf->len -= obuf->len; | |
1605 | } | |
1606 | ret += obuf->len; | |
1607 | len -= obuf->len; | |
1608 | } while (len); | |
1609 | ||
1610 | pipe_unlock(ipipe); | |
1611 | pipe_unlock(opipe); | |
1612 | ||
1613 | /* | |
1614 | * If we put data in the output pipe, wakeup any potential readers. | |
1615 | */ | |
825cdcb1 NK |
1616 | if (ret > 0) |
1617 | wakeup_pipe_readers(opipe); | |
1618 | ||
7c77f0b3 MS |
1619 | if (input_wakeup) |
1620 | wakeup_pipe_writers(ipipe); | |
1621 | ||
1622 | return ret; | |
1623 | } | |
1624 | ||
70524490 JA |
1625 | /* |
1626 | * Link contents of ipipe to opipe. | |
1627 | */ | |
1628 | static int link_pipe(struct pipe_inode_info *ipipe, | |
1629 | struct pipe_inode_info *opipe, | |
1630 | size_t len, unsigned int flags) | |
1631 | { | |
1632 | struct pipe_buffer *ibuf, *obuf; | |
aadd06e5 | 1633 | int ret = 0, i = 0, nbuf; |
70524490 JA |
1634 | |
1635 | /* | |
1636 | * Potential ABBA deadlock, work around it by ordering lock | |
61e0d47c | 1637 | * grabbing by pipe info address. Otherwise two different processes |
70524490 JA |
1638 | * could deadlock (one doing tee from A -> B, the other from B -> A). |
1639 | */ | |
61e0d47c | 1640 | pipe_double_lock(ipipe, opipe); |
70524490 | 1641 | |
aadd06e5 | 1642 | do { |
70524490 JA |
1643 | if (!opipe->readers) { |
1644 | send_sig(SIGPIPE, current, 0); | |
1645 | if (!ret) | |
1646 | ret = -EPIPE; | |
1647 | break; | |
1648 | } | |
70524490 | 1649 | |
aadd06e5 JA |
1650 | /* |
1651 | * If we have iterated all input buffers or ran out of | |
1652 | * output room, break. | |
1653 | */ | |
35f3d14d | 1654 | if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) |
aadd06e5 | 1655 | break; |
70524490 | 1656 | |
35f3d14d JA |
1657 | ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); |
1658 | nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); | |
70524490 JA |
1659 | |
1660 | /* | |
aadd06e5 JA |
1661 | * Get a reference to this pipe buffer, |
1662 | * so we can copy the contents over. | |
70524490 | 1663 | */ |
7bf2d1df | 1664 | pipe_buf_get(ipipe, ibuf); |
aadd06e5 JA |
1665 | |
1666 | obuf = opipe->bufs + nbuf; | |
1667 | *obuf = *ibuf; | |
1668 | ||
2a27250e | 1669 | /* |
aadd06e5 JA |
1670 | * Don't inherit the gift flag, we need to |
1671 | * prevent multiple steals of this page. | |
2a27250e | 1672 | */ |
aadd06e5 | 1673 | obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
70524490 | 1674 | |
aadd06e5 JA |
1675 | if (obuf->len > len) |
1676 | obuf->len = len; | |
70524490 | 1677 | |
aadd06e5 JA |
1678 | opipe->nrbufs++; |
1679 | ret += obuf->len; | |
1680 | len -= obuf->len; | |
1681 | i++; | |
1682 | } while (len); | |
70524490 | 1683 | |
02cf01ae JA |
1684 | /* |
1685 | * return EAGAIN if we have the potential of some data in the | |
1686 | * future, otherwise just return 0 | |
1687 | */ | |
1688 | if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) | |
1689 | ret = -EAGAIN; | |
1690 | ||
61e0d47c MS |
1691 | pipe_unlock(ipipe); |
1692 | pipe_unlock(opipe); | |
70524490 | 1693 | |
aadd06e5 JA |
1694 | /* |
1695 | * If we put data in the output pipe, wakeup any potential readers. | |
1696 | */ | |
825cdcb1 NK |
1697 | if (ret > 0) |
1698 | wakeup_pipe_readers(opipe); | |
70524490 JA |
1699 | |
1700 | return ret; | |
1701 | } | |
1702 | ||
1703 | /* | |
1704 | * This is a tee(1) implementation that works on pipes. It doesn't copy | |
1705 | * any data, it simply references the 'in' pages on the 'out' pipe. | |
1706 | * The 'flags' used are the SPLICE_F_* variants, currently the only | |
1707 | * applicable one is SPLICE_F_NONBLOCK. | |
1708 | */ | |
1709 | static long do_tee(struct file *in, struct file *out, size_t len, | |
1710 | unsigned int flags) | |
1711 | { | |
71993e62 LT |
1712 | struct pipe_inode_info *ipipe = get_pipe_info(in); |
1713 | struct pipe_inode_info *opipe = get_pipe_info(out); | |
aadd06e5 | 1714 | int ret = -EINVAL; |
70524490 JA |
1715 | |
1716 | /* | |
aadd06e5 JA |
1717 | * Duplicate the contents of ipipe to opipe without actually |
1718 | * copying the data. | |
70524490 | 1719 | */ |
aadd06e5 JA |
1720 | if (ipipe && opipe && ipipe != opipe) { |
1721 | /* | |
1722 | * Keep going, unless we encounter an error. The ipipe/opipe | |
1723 | * ordering doesn't really matter. | |
1724 | */ | |
7c77f0b3 | 1725 | ret = ipipe_prep(ipipe, flags); |
aadd06e5 | 1726 | if (!ret) { |
7c77f0b3 | 1727 | ret = opipe_prep(opipe, flags); |
02cf01ae | 1728 | if (!ret) |
aadd06e5 | 1729 | ret = link_pipe(ipipe, opipe, len, flags); |
aadd06e5 JA |
1730 | } |
1731 | } | |
70524490 | 1732 | |
aadd06e5 | 1733 | return ret; |
70524490 JA |
1734 | } |
1735 | ||
836f92ad | 1736 | SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
70524490 | 1737 | { |
2903ff01 AV |
1738 | struct fd in; |
1739 | int error; | |
70524490 JA |
1740 | |
1741 | if (unlikely(!len)) | |
1742 | return 0; | |
1743 | ||
1744 | error = -EBADF; | |
2903ff01 AV |
1745 | in = fdget(fdin); |
1746 | if (in.file) { | |
1747 | if (in.file->f_mode & FMODE_READ) { | |
1748 | struct fd out = fdget(fdout); | |
1749 | if (out.file) { | |
1750 | if (out.file->f_mode & FMODE_WRITE) | |
1751 | error = do_tee(in.file, out.file, | |
1752 | len, flags); | |
1753 | fdput(out); | |
70524490 JA |
1754 | } |
1755 | } | |
2903ff01 | 1756 | fdput(in); |
70524490 JA |
1757 | } |
1758 | ||
1759 | return error; | |
1760 | } |