blob: ed91a62402e028e81e4ebedb895fae6556b17a38 [file] [log] [blame]
Jens Axboe5274f052006-03-30 15:15:30 +02001/*
2 * "splice": joining two ropes together by interweaving their strands.
3 *
4 * This is the "extended pipe" functionality, where a pipe is used as
5 * an arbitrary in-memory buffer. Think of a pipe as a small kernel
6 * buffer that you can use to transfer data from one end to the other.
7 *
8 * The traditional unix read/write is extended with a "splice()" operation
9 * that transfers data buffers to or from a pipe buffer.
10 *
11 * Named by Larry McVoy, original implementation from Linus, extended by
12 * Jens to support splicing to files and fixing the initial implementation
13 * bugs.
14 *
15 * Copyright (C) 2005 Jens Axboe <axboe@suse.de>
16 * Copyright (C) 2005 Linus Torvalds <torvalds@osdl.org>
17 *
18 */
19#include <linux/fs.h>
20#include <linux/file.h>
21#include <linux/pagemap.h>
22#include <linux/pipe_fs_i.h>
23#include <linux/mm_inline.h>
Jens Axboe5abc97a2006-03-30 15:16:46 +020024#include <linux/swap.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020025#include <linux/writeback.h>
26#include <linux/buffer_head.h>
Jeff Garzika0f06782006-03-30 23:06:13 -050027#include <linux/module.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020028#include <linux/syscalls.h>
Jens Axboe5274f052006-03-30 15:15:30 +020029
30/*
31 * Passed to the actors
32 */
33struct splice_desc {
34 unsigned int len, total_len; /* current and remaining length */
35 unsigned int flags; /* splice flags */
36 struct file *file; /* file to read/write */
37 loff_t pos; /* file position */
38};
39
Jens Axboe83f91352006-04-02 23:05:09 +020040/*
41 * Attempt to steal a page from a pipe buffer. This should perhaps go into
42 * a vm helper function, it's already simplified quite a bit by the
43 * addition of remove_mapping(). If success is returned, the caller may
44 * attempt to reuse this page for another destination.
45 */
Jens Axboe5abc97a2006-03-30 15:16:46 +020046static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
47 struct pipe_buffer *buf)
48{
49 struct page *page = buf->page;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020050 struct address_space *mapping = page_mapping(page);
Jens Axboe5abc97a2006-03-30 15:16:46 +020051
52 WARN_ON(!PageLocked(page));
53 WARN_ON(!PageUptodate(page));
54
Jens Axboead8d6f02006-04-02 23:10:32 +020055 /*
56 * At least for ext2 with nobh option, we need to wait on writeback
57 * completing on this page, since we'll remove it from the pagecache.
58 * Otherwise truncate wont wait on the page, allowing the disk
59 * blocks to be reused by someone else before we actually wrote our
60 * data to them. fs corruption ensues.
61 */
62 wait_on_page_writeback(page);
63
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020064 if (PagePrivate(page))
65 try_to_release_page(page, mapping_gfp_mask(mapping));
66
67 if (!remove_mapping(mapping, page))
Jens Axboe5abc97a2006-03-30 15:16:46 +020068 return 1;
69
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020070 buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
Jens Axboe5abc97a2006-03-30 15:16:46 +020071 return 0;
72}
73
Jens Axboe5274f052006-03-30 15:15:30 +020074static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
75 struct pipe_buffer *buf)
76{
77 page_cache_release(buf->page);
78 buf->page = NULL;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +020079 buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU);
Jens Axboe5274f052006-03-30 15:15:30 +020080}
81
82static void *page_cache_pipe_buf_map(struct file *file,
83 struct pipe_inode_info *info,
84 struct pipe_buffer *buf)
85{
86 struct page *page = buf->page;
Jens Axboe49d0b212006-04-10 09:04:41 +020087 int err;
Jens Axboe5274f052006-03-30 15:15:30 +020088
89 if (!PageUptodate(page)) {
Jens Axboe49d0b212006-04-10 09:04:41 +020090 lock_page(page);
91
92 /*
93 * Page got truncated/unhashed. This will cause a 0-byte
94 * splice, if this is the first page
95 */
96 if (!page->mapping) {
97 err = -ENODATA;
98 goto error;
99 }
100
101 /*
102 * uh oh, read-error from disk
103 */
104 if (!PageUptodate(page)) {
105 err = -EIO;
106 goto error;
107 }
108
109 /*
110 * page is ok afterall, fall through to mapping
111 */
Jens Axboe5274f052006-03-30 15:15:30 +0200112 unlock_page(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200113 }
114
Jens Axboe49d0b212006-04-10 09:04:41 +0200115 return kmap(page);
116error:
117 unlock_page(page);
118 return ERR_PTR(err);
Jens Axboe5274f052006-03-30 15:15:30 +0200119}
120
121static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
122 struct pipe_buffer *buf)
123{
Jens Axboe5274f052006-03-30 15:15:30 +0200124 kunmap(buf->page);
125}
126
127static struct pipe_buf_operations page_cache_pipe_buf_ops = {
128 .can_merge = 0,
129 .map = page_cache_pipe_buf_map,
130 .unmap = page_cache_pipe_buf_unmap,
131 .release = page_cache_pipe_buf_release,
Jens Axboe5abc97a2006-03-30 15:16:46 +0200132 .steal = page_cache_pipe_buf_steal,
Jens Axboe5274f052006-03-30 15:15:30 +0200133};
134
Jens Axboe83f91352006-04-02 23:05:09 +0200135/*
136 * Pipe output worker. This sets up our pipe format with the page cache
137 * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
138 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200139static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
Jens Axboe5274f052006-03-30 15:15:30 +0200140 int nr_pages, unsigned long offset,
Linus Torvalds29e35092006-04-02 12:46:35 -0700141 unsigned long len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200142{
Jens Axboe5274f052006-03-30 15:15:30 +0200143 int ret, do_wakeup, i;
144
145 ret = 0;
146 do_wakeup = 0;
147 i = 0;
148
Ingo Molnar3a326a22006-04-10 15:18:35 +0200149 if (pipe->inode)
150 mutex_lock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200151
Jens Axboe5274f052006-03-30 15:15:30 +0200152 for (;;) {
153 int bufs;
154
Ingo Molnar3a326a22006-04-10 15:18:35 +0200155 if (!pipe->readers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200156 send_sig(SIGPIPE, current, 0);
157 if (!ret)
158 ret = -EPIPE;
159 break;
160 }
161
Ingo Molnar3a326a22006-04-10 15:18:35 +0200162 bufs = pipe->nrbufs;
Jens Axboe5274f052006-03-30 15:15:30 +0200163 if (bufs < PIPE_BUFFERS) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200164 int newbuf = (pipe->curbuf + bufs) & (PIPE_BUFFERS - 1);
165 struct pipe_buffer *buf = pipe->bufs + newbuf;
Jens Axboe5274f052006-03-30 15:15:30 +0200166 struct page *page = pages[i++];
167 unsigned long this_len;
168
169 this_len = PAGE_CACHE_SIZE - offset;
170 if (this_len > len)
171 this_len = len;
172
173 buf->page = page;
174 buf->offset = offset;
175 buf->len = this_len;
176 buf->ops = &page_cache_pipe_buf_ops;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200177 pipe->nrbufs = ++bufs;
Jens Axboe5274f052006-03-30 15:15:30 +0200178 do_wakeup = 1;
179
180 ret += this_len;
181 len -= this_len;
182 offset = 0;
183 if (!--nr_pages)
184 break;
185 if (!len)
186 break;
187 if (bufs < PIPE_BUFFERS)
188 continue;
189
190 break;
191 }
192
Linus Torvalds29e35092006-04-02 12:46:35 -0700193 if (flags & SPLICE_F_NONBLOCK) {
194 if (!ret)
195 ret = -EAGAIN;
196 break;
197 }
198
Jens Axboe5274f052006-03-30 15:15:30 +0200199 if (signal_pending(current)) {
200 if (!ret)
201 ret = -ERESTARTSYS;
202 break;
203 }
204
205 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200206 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200207 if (waitqueue_active(&pipe->wait))
208 wake_up_interruptible_sync(&pipe->wait);
209 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
Jens Axboe5274f052006-03-30 15:15:30 +0200210 do_wakeup = 0;
211 }
212
Ingo Molnar3a326a22006-04-10 15:18:35 +0200213 pipe->waiting_writers++;
214 pipe_wait(pipe);
215 pipe->waiting_writers--;
Jens Axboe5274f052006-03-30 15:15:30 +0200216 }
217
Ingo Molnar3a326a22006-04-10 15:18:35 +0200218 if (pipe->inode)
219 mutex_unlock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200220
221 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200222 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200223 if (waitqueue_active(&pipe->wait))
224 wake_up_interruptible(&pipe->wait);
225 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
Jens Axboe5274f052006-03-30 15:15:30 +0200226 }
227
228 while (i < nr_pages)
229 page_cache_release(pages[i++]);
230
231 return ret;
232}
233
Ingo Molnar3a326a22006-04-10 15:18:35 +0200234static int
235__generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
236 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200237{
238 struct address_space *mapping = in->f_mapping;
239 unsigned int offset, nr_pages;
Jens Axboe16c523d2006-04-10 09:03:58 +0200240 struct page *pages[PIPE_BUFFERS];
Jens Axboe5274f052006-03-30 15:15:30 +0200241 struct page *page;
Jens Axboe16c523d2006-04-10 09:03:58 +0200242 pgoff_t index;
243 int i;
Jens Axboe5274f052006-03-30 15:15:30 +0200244
245 index = in->f_pos >> PAGE_CACHE_SHIFT;
246 offset = in->f_pos & ~PAGE_CACHE_MASK;
247 nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
248
249 if (nr_pages > PIPE_BUFFERS)
250 nr_pages = PIPE_BUFFERS;
251
252 /*
Jens Axboe0b749ce2006-04-10 09:05:04 +0200253 * initiate read-ahead on this page range. however, don't call into
254 * read-ahead if this is a non-zero offset (we are likely doing small
255 * chunk splice and the page is already there) for a single page.
Jens Axboe5274f052006-03-30 15:15:30 +0200256 */
Jens Axboe0b749ce2006-04-10 09:05:04 +0200257 if (!offset || nr_pages > 1)
258 do_page_cache_readahead(mapping, in, index, nr_pages);
Jens Axboe5274f052006-03-30 15:15:30 +0200259
260 /*
Jens Axboe5274f052006-03-30 15:15:30 +0200261 * now fill in the holes
262 */
Jens Axboe16c523d2006-04-10 09:03:58 +0200263 for (i = 0; i < nr_pages; i++, index++) {
Jens Axboe5274f052006-03-30 15:15:30 +0200264 /*
265 * no page there, look one up / create it
266 */
Jens Axboe16c523d2006-04-10 09:03:58 +0200267 page = find_or_create_page(mapping, index,
Jens Axboe5274f052006-03-30 15:15:30 +0200268 mapping_gfp_mask(mapping));
269 if (!page)
270 break;
271
272 if (PageUptodate(page))
273 unlock_page(page);
274 else {
Jens Axboe16c523d2006-04-10 09:03:58 +0200275 int error = mapping->a_ops->readpage(in, page);
Jens Axboe5274f052006-03-30 15:15:30 +0200276
277 if (unlikely(error)) {
278 page_cache_release(page);
279 break;
280 }
281 }
Jens Axboe16c523d2006-04-10 09:03:58 +0200282 pages[i] = page;
Jens Axboe5274f052006-03-30 15:15:30 +0200283 }
284
Jens Axboe16c523d2006-04-10 09:03:58 +0200285 if (i)
286 return move_to_pipe(pipe, pages, i, offset, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200287
Jens Axboe16c523d2006-04-10 09:03:58 +0200288 return 0;
Jens Axboe5274f052006-03-30 15:15:30 +0200289}
290
Jens Axboe83f91352006-04-02 23:05:09 +0200291/**
292 * generic_file_splice_read - splice data from file to a pipe
293 * @in: file to splice from
294 * @pipe: pipe to splice to
295 * @len: number of bytes to splice
296 * @flags: splice modifier flags
297 *
298 * Will read pages from given file and fill them into a pipe.
299 *
300 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200301ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +0200302 size_t len, unsigned int flags)
303{
304 ssize_t spliced;
305 int ret;
306
307 ret = 0;
308 spliced = 0;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200309
Jens Axboe5274f052006-03-30 15:15:30 +0200310 while (len) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700311 ret = __generic_file_splice_read(in, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200312
313 if (ret <= 0)
314 break;
315
316 in->f_pos += ret;
317 len -= ret;
318 spliced += ret;
Linus Torvalds29e35092006-04-02 12:46:35 -0700319
320 if (!(flags & SPLICE_F_NONBLOCK))
321 continue;
322 ret = -EAGAIN;
323 break;
Jens Axboe5274f052006-03-30 15:15:30 +0200324 }
325
326 if (spliced)
327 return spliced;
328
329 return ret;
330}
331
Jens Axboe059a8f32006-04-02 23:06:05 +0200332EXPORT_SYMBOL(generic_file_splice_read);
333
Jens Axboe5274f052006-03-30 15:15:30 +0200334/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200335 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
336 * using sendpage().
Jens Axboe5274f052006-03-30 15:15:30 +0200337 */
338static int pipe_to_sendpage(struct pipe_inode_info *info,
339 struct pipe_buffer *buf, struct splice_desc *sd)
340{
341 struct file *file = sd->file;
342 loff_t pos = sd->pos;
343 unsigned int offset;
344 ssize_t ret;
345 void *ptr;
Jens Axboeb2b39fa2006-04-02 23:05:41 +0200346 int more;
Jens Axboe5274f052006-03-30 15:15:30 +0200347
348 /*
349 * sub-optimal, but we are limited by the pipe ->map. we don't
350 * need a kmap'ed buffer here, we just want to make sure we
351 * have the page pinned if the pipe page originates from the
352 * page cache
353 */
354 ptr = buf->ops->map(file, info, buf);
355 if (IS_ERR(ptr))
356 return PTR_ERR(ptr);
357
358 offset = pos & ~PAGE_CACHE_MASK;
Jens Axboeb2b39fa2006-04-02 23:05:41 +0200359 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200360
Jens Axboeb2b39fa2006-04-02 23:05:41 +0200361 ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more);
Jens Axboe5274f052006-03-30 15:15:30 +0200362
363 buf->ops->unmap(info, buf);
364 if (ret == sd->len)
365 return 0;
366
367 return -EIO;
368}
369
370/*
371 * This is a little more tricky than the file -> pipe splicing. There are
372 * basically three cases:
373 *
374 * - Destination page already exists in the address space and there
375 * are users of it. For that case we have no other option that
376 * copying the data. Tough luck.
377 * - Destination page already exists in the address space, but there
378 * are no users of it. Make sure it's uptodate, then drop it. Fall
379 * through to last case.
380 * - Destination page does not exist, we can add the pipe page to
381 * the page cache and avoid the copy.
382 *
Jens Axboe83f91352006-04-02 23:05:09 +0200383 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
384 * sd->flags), we attempt to migrate pages from the pipe to the output
385 * file address space page cache. This is possible if no one else has
386 * the pipe page referenced outside of the pipe and page cache. If
387 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
388 * a new page in the output file page cache and fill/dirty that.
Jens Axboe5274f052006-03-30 15:15:30 +0200389 */
390static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
391 struct splice_desc *sd)
392{
393 struct file *file = sd->file;
394 struct address_space *mapping = file->f_mapping;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200395 gfp_t gfp_mask = mapping_gfp_mask(mapping);
Jens Axboe5274f052006-03-30 15:15:30 +0200396 unsigned int offset;
397 struct page *page;
Jens Axboe5274f052006-03-30 15:15:30 +0200398 pgoff_t index;
Jens Axboe5abc97a2006-03-30 15:16:46 +0200399 char *src;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200400 int ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200401
402 /*
Jens Axboe49d0b212006-04-10 09:04:41 +0200403 * make sure the data in this buffer is uptodate
Jens Axboe5274f052006-03-30 15:15:30 +0200404 */
405 src = buf->ops->map(file, info, buf);
406 if (IS_ERR(src))
407 return PTR_ERR(src);
408
409 index = sd->pos >> PAGE_CACHE_SHIFT;
410 offset = sd->pos & ~PAGE_CACHE_MASK;
411
Jens Axboe5274f052006-03-30 15:15:30 +0200412 /*
Jens Axboe5abc97a2006-03-30 15:16:46 +0200413 * reuse buf page, if SPLICE_F_MOVE is set
Jens Axboe5274f052006-03-30 15:15:30 +0200414 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200415 if (sd->flags & SPLICE_F_MOVE) {
Jens Axboe83f91352006-04-02 23:05:09 +0200416 /*
417 * If steal succeeds, buf->page is now pruned from the vm
418 * side (LRU and page cache) and we can reuse it.
419 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200420 if (buf->ops->steal(info, buf))
421 goto find_page;
Jens Axboe5274f052006-03-30 15:15:30 +0200422
Jens Axboe49d0b212006-04-10 09:04:41 +0200423 /*
424 * this will also set the page locked
425 */
Jens Axboe5abc97a2006-03-30 15:16:46 +0200426 page = buf->page;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200427 if (add_to_page_cache(page, mapping, index, gfp_mask))
Jens Axboe5abc97a2006-03-30 15:16:46 +0200428 goto find_page;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200429
430 if (!(buf->flags & PIPE_BUF_FLAG_LRU))
431 lru_cache_add(page);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200432 } else {
433find_page:
434 ret = -ENOMEM;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200435 page = find_or_create_page(mapping, index, gfp_mask);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200436 if (!page)
Dave Jones9aefe432006-04-10 09:02:40 +0200437 goto out_nomem;
Jens Axboe5274f052006-03-30 15:15:30 +0200438
Jens Axboe5abc97a2006-03-30 15:16:46 +0200439 /*
440 * If the page is uptodate, it is also locked. If it isn't
441 * uptodate, we can mark it uptodate if we are filling the
442 * full page. Otherwise we need to read it in first...
443 */
444 if (!PageUptodate(page)) {
445 if (sd->len < PAGE_CACHE_SIZE) {
446 ret = mapping->a_ops->readpage(file, page);
447 if (unlikely(ret))
448 goto out;
449
450 lock_page(page);
451
452 if (!PageUptodate(page)) {
453 /*
454 * page got invalidated, repeat
455 */
456 if (!page->mapping) {
457 unlock_page(page);
458 page_cache_release(page);
459 goto find_page;
460 }
461 ret = -EIO;
462 goto out;
Jens Axboe5274f052006-03-30 15:15:30 +0200463 }
Jens Axboe5abc97a2006-03-30 15:16:46 +0200464 } else {
465 WARN_ON(!PageLocked(page));
466 SetPageUptodate(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200467 }
Jens Axboe5274f052006-03-30 15:15:30 +0200468 }
469 }
470
471 ret = mapping->a_ops->prepare_write(file, page, 0, sd->len);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200472 if (ret == AOP_TRUNCATED_PAGE) {
473 page_cache_release(page);
474 goto find_page;
475 } else if (ret)
Jens Axboe5274f052006-03-30 15:15:30 +0200476 goto out;
477
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200478 if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
Jens Axboe5abc97a2006-03-30 15:16:46 +0200479 char *dst = kmap_atomic(page, KM_USER0);
480
481 memcpy(dst + offset, src + buf->offset, sd->len);
482 flush_dcache_page(page);
483 kunmap_atomic(dst, KM_USER0);
484 }
Jens Axboe5274f052006-03-30 15:15:30 +0200485
486 ret = mapping->a_ops->commit_write(file, page, 0, sd->len);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200487 if (ret == AOP_TRUNCATED_PAGE) {
488 page_cache_release(page);
489 goto find_page;
490 } else if (ret)
Jens Axboe5274f052006-03-30 15:15:30 +0200491 goto out;
492
Jens Axboec7f21e42006-04-10 09:01:01 +0200493 mark_page_accessed(page);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200494 balance_dirty_pages_ratelimited(mapping);
Jens Axboe5274f052006-03-30 15:15:30 +0200495out:
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200496 if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
Jens Axboe5abc97a2006-03-30 15:16:46 +0200497 page_cache_release(page);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200498 unlock_page(page);
499 }
Dave Jones9aefe432006-04-10 09:02:40 +0200500out_nomem:
Jens Axboe5274f052006-03-30 15:15:30 +0200501 buf->ops->unmap(info, buf);
502 return ret;
503}
504
505typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
506 struct splice_desc *);
507
Jens Axboe83f91352006-04-02 23:05:09 +0200508/*
509 * Pipe input worker. Most of this logic works like a regular pipe, the
510 * key here is the 'actor' worker passed in that actually moves the data
511 * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
512 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200513static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
Jens Axboe5274f052006-03-30 15:15:30 +0200514 size_t len, unsigned int flags,
515 splice_actor *actor)
516{
Jens Axboe5274f052006-03-30 15:15:30 +0200517 int ret, do_wakeup, err;
518 struct splice_desc sd;
519
520 ret = 0;
521 do_wakeup = 0;
522
523 sd.total_len = len;
524 sd.flags = flags;
525 sd.file = out;
526 sd.pos = out->f_pos;
527
Ingo Molnar3a326a22006-04-10 15:18:35 +0200528 if (pipe->inode)
529 mutex_lock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200530
Jens Axboe5274f052006-03-30 15:15:30 +0200531 for (;;) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200532 int bufs = pipe->nrbufs;
Jens Axboe5274f052006-03-30 15:15:30 +0200533
534 if (bufs) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200535 int curbuf = pipe->curbuf;
536 struct pipe_buffer *buf = pipe->bufs + curbuf;
Jens Axboe5274f052006-03-30 15:15:30 +0200537 struct pipe_buf_operations *ops = buf->ops;
538
539 sd.len = buf->len;
540 if (sd.len > sd.total_len)
541 sd.len = sd.total_len;
542
Ingo Molnar3a326a22006-04-10 15:18:35 +0200543 err = actor(pipe, buf, &sd);
Jens Axboe5274f052006-03-30 15:15:30 +0200544 if (err) {
545 if (!ret && err != -ENODATA)
546 ret = err;
547
548 break;
549 }
550
551 ret += sd.len;
552 buf->offset += sd.len;
553 buf->len -= sd.len;
554 if (!buf->len) {
555 buf->ops = NULL;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200556 ops->release(pipe, buf);
Jens Axboe5274f052006-03-30 15:15:30 +0200557 curbuf = (curbuf + 1) & (PIPE_BUFFERS - 1);
Ingo Molnar3a326a22006-04-10 15:18:35 +0200558 pipe->curbuf = curbuf;
559 pipe->nrbufs = --bufs;
Jens Axboe5274f052006-03-30 15:15:30 +0200560 do_wakeup = 1;
561 }
562
563 sd.pos += sd.len;
564 sd.total_len -= sd.len;
565 if (!sd.total_len)
566 break;
567 }
568
569 if (bufs)
570 continue;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200571 if (!pipe->writers)
Jens Axboe5274f052006-03-30 15:15:30 +0200572 break;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200573 if (!pipe->waiting_writers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200574 if (ret)
575 break;
576 }
577
Linus Torvalds29e35092006-04-02 12:46:35 -0700578 if (flags & SPLICE_F_NONBLOCK) {
579 if (!ret)
580 ret = -EAGAIN;
581 break;
582 }
583
Jens Axboe5274f052006-03-30 15:15:30 +0200584 if (signal_pending(current)) {
585 if (!ret)
586 ret = -ERESTARTSYS;
587 break;
588 }
589
590 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200591 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200592 if (waitqueue_active(&pipe->wait))
593 wake_up_interruptible_sync(&pipe->wait);
594 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
Jens Axboe5274f052006-03-30 15:15:30 +0200595 do_wakeup = 0;
596 }
597
Ingo Molnar3a326a22006-04-10 15:18:35 +0200598 pipe_wait(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200599 }
600
Ingo Molnar3a326a22006-04-10 15:18:35 +0200601 if (pipe->inode)
602 mutex_unlock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200603
604 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200605 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200606 if (waitqueue_active(&pipe->wait))
607 wake_up_interruptible(&pipe->wait);
608 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
Jens Axboe5274f052006-03-30 15:15:30 +0200609 }
610
611 mutex_lock(&out->f_mapping->host->i_mutex);
612 out->f_pos = sd.pos;
613 mutex_unlock(&out->f_mapping->host->i_mutex);
614 return ret;
615
616}
617
Jens Axboe83f91352006-04-02 23:05:09 +0200618/**
619 * generic_file_splice_write - splice data from a pipe to a file
Ingo Molnar3a326a22006-04-10 15:18:35 +0200620 * @pipe: pipe info
Jens Axboe83f91352006-04-02 23:05:09 +0200621 * @out: file to write to
622 * @len: number of bytes to splice
623 * @flags: splice modifier flags
624 *
625 * Will either move or copy pages (determined by @flags options) from
626 * the given pipe inode to the given file.
627 *
628 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200629ssize_t
630generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
631 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200632{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200633 struct address_space *mapping = out->f_mapping;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200634 ssize_t ret;
635
636 ret = move_from_pipe(pipe, out, len, flags, pipe_to_file);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200637
638 /*
639 * if file or inode is SYNC and we actually wrote some data, sync it
640 */
641 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host))
642 && ret > 0) {
643 struct inode *inode = mapping->host;
644 int err;
645
646 mutex_lock(&inode->i_mutex);
647 err = generic_osync_inode(mapping->host, mapping,
648 OSYNC_METADATA|OSYNC_DATA);
649 mutex_unlock(&inode->i_mutex);
650
651 if (err)
652 ret = err;
653 }
654
655 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200656}
657
Jens Axboe059a8f32006-04-02 23:06:05 +0200658EXPORT_SYMBOL(generic_file_splice_write);
659
Jens Axboe83f91352006-04-02 23:05:09 +0200660/**
661 * generic_splice_sendpage - splice data from a pipe to a socket
662 * @inode: pipe inode
663 * @out: socket to write to
664 * @len: number of bytes to splice
665 * @flags: splice modifier flags
666 *
667 * Will send @len bytes from the pipe to a network socket. No data copying
668 * is involved.
669 *
670 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200671ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
Jens Axboe5274f052006-03-30 15:15:30 +0200672 size_t len, unsigned int flags)
673{
Ingo Molnar3a326a22006-04-10 15:18:35 +0200674 return move_from_pipe(pipe, out, len, flags, pipe_to_sendpage);
Jens Axboe5274f052006-03-30 15:15:30 +0200675}
676
Jens Axboe059a8f32006-04-02 23:06:05 +0200677EXPORT_SYMBOL(generic_splice_sendpage);
Jeff Garzika0f06782006-03-30 23:06:13 -0500678
Jens Axboe83f91352006-04-02 23:05:09 +0200679/*
680 * Attempt to initiate a splice from pipe to file.
681 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200682static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
683 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200684{
685 loff_t pos;
686 int ret;
687
688 if (!out->f_op || !out->f_op->splice_write)
689 return -EINVAL;
690
691 if (!(out->f_mode & FMODE_WRITE))
692 return -EBADF;
693
694 pos = out->f_pos;
695 ret = rw_verify_area(WRITE, out, &pos, len);
696 if (unlikely(ret < 0))
697 return ret;
698
699 return out->f_op->splice_write(pipe, out, len, flags);
700}
701
Jens Axboe83f91352006-04-02 23:05:09 +0200702/*
703 * Attempt to initiate a splice from a file to a pipe.
704 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200705static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
706 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200707{
708 loff_t pos, isize, left;
709 int ret;
710
711 if (!in->f_op || !in->f_op->splice_read)
712 return -EINVAL;
713
714 if (!(in->f_mode & FMODE_READ))
715 return -EBADF;
716
717 pos = in->f_pos;
718 ret = rw_verify_area(READ, in, &pos, len);
719 if (unlikely(ret < 0))
720 return ret;
721
722 isize = i_size_read(in->f_mapping->host);
723 if (unlikely(in->f_pos >= isize))
724 return 0;
725
726 left = isize - in->f_pos;
727 if (left < len)
728 len = left;
729
730 return in->f_op->splice_read(in, pipe, len, flags);
731}
732
Jens Axboe83f91352006-04-02 23:05:09 +0200733/*
734 * Determine where to splice to/from.
735 */
Jens Axboe5274f052006-03-30 15:15:30 +0200736static long do_splice(struct file *in, struct file *out, size_t len,
737 unsigned int flags)
738{
Ingo Molnar3a326a22006-04-10 15:18:35 +0200739 struct pipe_inode_info *pipe;
Jens Axboe5274f052006-03-30 15:15:30 +0200740
Ingo Molnar3a326a22006-04-10 15:18:35 +0200741 pipe = in->f_dentry->d_inode->i_pipe;
742 if (pipe)
Jens Axboe5274f052006-03-30 15:15:30 +0200743 return do_splice_from(pipe, out, len, flags);
744
Ingo Molnar3a326a22006-04-10 15:18:35 +0200745 pipe = out->f_dentry->d_inode->i_pipe;
746 if (pipe)
Jens Axboe5274f052006-03-30 15:15:30 +0200747 return do_splice_to(in, pipe, len, flags);
748
749 return -EINVAL;
750}
751
752asmlinkage long sys_splice(int fdin, int fdout, size_t len, unsigned int flags)
753{
754 long error;
755 struct file *in, *out;
756 int fput_in, fput_out;
757
758 if (unlikely(!len))
759 return 0;
760
761 error = -EBADF;
762 in = fget_light(fdin, &fput_in);
763 if (in) {
764 if (in->f_mode & FMODE_READ) {
765 out = fget_light(fdout, &fput_out);
766 if (out) {
767 if (out->f_mode & FMODE_WRITE)
768 error = do_splice(in, out, len, flags);
769 fput_light(out, fput_out);
770 }
771 }
772
773 fput_light(in, fput_in);
774 }
775
776 return error;
777}