blob: 9313b6124a2e40c7824e6f03b4fc5af72c1cd00a [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
Jens Axboec2058e02006-04-11 13:56:34 +020012 * Jens to support splicing to files, network, direct splicing, etc and
13 * fixing lots of bugs.
Jens Axboe5274f052006-03-30 15:15:30 +020014 *
Jens Axboe0fe23472006-09-04 15:41:16 +020015 * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
Jens Axboec2058e02006-04-11 13:56:34 +020016 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
17 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
Jens Axboe5274f052006-03-30 15:15:30 +020018 *
19 */
20#include <linux/fs.h>
21#include <linux/file.h>
22#include <linux/pagemap.h>
Jens Axboed6b29d72007-06-04 09:59:47 +020023#include <linux/splice.h>
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -080024#include <linux/memcontrol.h>
Jens Axboe5274f052006-03-30 15:15:30 +020025#include <linux/mm_inline.h>
Jens Axboe5abc97a2006-03-30 15:16:46 +020026#include <linux/swap.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020027#include <linux/writeback.h>
28#include <linux/buffer_head.h>
Jeff Garzika0f06782006-03-30 23:06:13 -050029#include <linux/module.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020030#include <linux/syscalls.h>
Jens Axboe912d35f2006-04-26 10:59:21 +020031#include <linux/uio.h>
James Morris29ce2052007-07-13 11:44:32 +020032#include <linux/security.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090033#include <linux/gfp.h>
Jens Axboe5274f052006-03-30 15:15:30 +020034
Jens Axboe83f91352006-04-02 23:05:09 +020035/*
36 * Attempt to steal a page from a pipe buffer. This should perhaps go into
37 * a vm helper function, it's already simplified quite a bit by the
38 * addition of remove_mapping(). If success is returned, the caller may
39 * attempt to reuse this page for another destination.
40 */
Jens Axboe76ad4d12006-05-03 10:41:33 +020041static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
Jens Axboe5abc97a2006-03-30 15:16:46 +020042 struct pipe_buffer *buf)
43{
44 struct page *page = buf->page;
Jens Axboe9e94cd42006-06-20 15:01:12 +020045 struct address_space *mapping;
Jens Axboe5abc97a2006-03-30 15:16:46 +020046
Jens Axboe9e0267c2006-04-19 15:57:31 +020047 lock_page(page);
48
Jens Axboe9e94cd42006-06-20 15:01:12 +020049 mapping = page_mapping(page);
50 if (mapping) {
51 WARN_ON(!PageUptodate(page));
Jens Axboe5abc97a2006-03-30 15:16:46 +020052
Jens Axboe9e94cd42006-06-20 15:01:12 +020053 /*
54 * At least for ext2 with nobh option, we need to wait on
55 * writeback completing on this page, since we'll remove it
56 * from the pagecache. Otherwise truncate wont wait on the
57 * page, allowing the disk blocks to be reused by someone else
58 * before we actually wrote our data to them. fs corruption
59 * ensues.
60 */
61 wait_on_page_writeback(page);
Jens Axboead8d6f02006-04-02 23:10:32 +020062
David Howells266cf652009-04-03 16:42:36 +010063 if (page_has_private(page) &&
64 !try_to_release_page(page, GFP_KERNEL))
Jens Axboeca39d652008-05-20 21:27:41 +020065 goto out_unlock;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020066
Jens Axboe9e94cd42006-06-20 15:01:12 +020067 /*
68 * If we succeeded in removing the mapping, set LRU flag
69 * and return good.
70 */
71 if (remove_mapping(mapping, page)) {
72 buf->flags |= PIPE_BUF_FLAG_LRU;
73 return 0;
74 }
Jens Axboe9e0267c2006-04-19 15:57:31 +020075 }
Jens Axboe5abc97a2006-03-30 15:16:46 +020076
Jens Axboe9e94cd42006-06-20 15:01:12 +020077 /*
78 * Raced with truncate or failed to remove page from current
79 * address space, unlock and return failure.
80 */
Jens Axboeca39d652008-05-20 21:27:41 +020081out_unlock:
Jens Axboe9e94cd42006-06-20 15:01:12 +020082 unlock_page(page);
83 return 1;
Jens Axboe5abc97a2006-03-30 15:16:46 +020084}
85
Jens Axboe76ad4d12006-05-03 10:41:33 +020086static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +020087 struct pipe_buffer *buf)
88{
89 page_cache_release(buf->page);
Jens Axboe14328732006-05-03 10:35:26 +020090 buf->flags &= ~PIPE_BUF_FLAG_LRU;
Jens Axboe5274f052006-03-30 15:15:30 +020091}
92
Jens Axboe08457182007-06-12 20:51:32 +020093/*
94 * Check whether the contents of buf is OK to access. Since the content
95 * is a page cache page, IO may be in flight.
96 */
Jens Axboecac36bb2007-06-14 13:10:48 +020097static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
98 struct pipe_buffer *buf)
Jens Axboe5274f052006-03-30 15:15:30 +020099{
100 struct page *page = buf->page;
Jens Axboe49d0b212006-04-10 09:04:41 +0200101 int err;
Jens Axboe5274f052006-03-30 15:15:30 +0200102
103 if (!PageUptodate(page)) {
Jens Axboe49d0b212006-04-10 09:04:41 +0200104 lock_page(page);
105
106 /*
107 * Page got truncated/unhashed. This will cause a 0-byte
Ingo Molnar73d62d82006-04-11 13:57:21 +0200108 * splice, if this is the first page.
Jens Axboe49d0b212006-04-10 09:04:41 +0200109 */
110 if (!page->mapping) {
111 err = -ENODATA;
112 goto error;
113 }
114
115 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +0200116 * Uh oh, read-error from disk.
Jens Axboe49d0b212006-04-10 09:04:41 +0200117 */
118 if (!PageUptodate(page)) {
119 err = -EIO;
120 goto error;
121 }
122
123 /*
Jens Axboef84d7512006-05-01 19:59:03 +0200124 * Page is ok afterall, we are done.
Jens Axboe49d0b212006-04-10 09:04:41 +0200125 */
Jens Axboe5274f052006-03-30 15:15:30 +0200126 unlock_page(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200127 }
128
Jens Axboef84d7512006-05-01 19:59:03 +0200129 return 0;
Jens Axboe49d0b212006-04-10 09:04:41 +0200130error:
131 unlock_page(page);
Jens Axboef84d7512006-05-01 19:59:03 +0200132 return err;
Jens Axboe70524492006-04-11 15:51:17 +0200133}
134
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800135static const struct pipe_buf_operations page_cache_pipe_buf_ops = {
Jens Axboe5274f052006-03-30 15:15:30 +0200136 .can_merge = 0,
Jens Axboef84d7512006-05-01 19:59:03 +0200137 .map = generic_pipe_buf_map,
138 .unmap = generic_pipe_buf_unmap,
Jens Axboecac36bb2007-06-14 13:10:48 +0200139 .confirm = page_cache_pipe_buf_confirm,
Jens Axboe5274f052006-03-30 15:15:30 +0200140 .release = page_cache_pipe_buf_release,
Jens Axboe5abc97a2006-03-30 15:16:46 +0200141 .steal = page_cache_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200142 .get = generic_pipe_buf_get,
Jens Axboe5274f052006-03-30 15:15:30 +0200143};
144
Jens Axboe912d35f2006-04-26 10:59:21 +0200145static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
146 struct pipe_buffer *buf)
147{
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200148 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
149 return 1;
150
Jens Axboe14328732006-05-03 10:35:26 +0200151 buf->flags |= PIPE_BUF_FLAG_LRU;
Jens Axboe330ab712006-05-02 15:29:57 +0200152 return generic_pipe_buf_steal(pipe, buf);
Jens Axboe912d35f2006-04-26 10:59:21 +0200153}
154
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800155static const struct pipe_buf_operations user_page_pipe_buf_ops = {
Jens Axboe912d35f2006-04-26 10:59:21 +0200156 .can_merge = 0,
Jens Axboef84d7512006-05-01 19:59:03 +0200157 .map = generic_pipe_buf_map,
158 .unmap = generic_pipe_buf_unmap,
Jens Axboecac36bb2007-06-14 13:10:48 +0200159 .confirm = generic_pipe_buf_confirm,
Jens Axboe912d35f2006-04-26 10:59:21 +0200160 .release = page_cache_pipe_buf_release,
161 .steal = user_page_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200162 .get = generic_pipe_buf_get,
Jens Axboe912d35f2006-04-26 10:59:21 +0200163};
164
Jens Axboe932cc6d2007-06-21 13:10:21 +0200165/**
166 * splice_to_pipe - fill passed data into a pipe
167 * @pipe: pipe to fill
168 * @spd: data to fill
169 *
170 * Description:
Randy Dunlap79685b82007-07-27 08:08:51 +0200171 * @spd contains a map of pages and len/offset tuples, along with
Jens Axboe932cc6d2007-06-21 13:10:21 +0200172 * the struct pipe_buf_operations associated with these pages. This
173 * function will link that data to the pipe.
174 *
Jens Axboe83f91352006-04-02 23:05:09 +0200175 */
Jens Axboed6b29d72007-06-04 09:59:47 +0200176ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
177 struct splice_pipe_desc *spd)
Jens Axboe5274f052006-03-30 15:15:30 +0200178{
Jens Axboe00de00b2007-06-15 13:14:22 +0200179 unsigned int spd_pages = spd->nr_pages;
Jens Axboe912d35f2006-04-26 10:59:21 +0200180 int ret, do_wakeup, page_nr;
Jens Axboe5274f052006-03-30 15:15:30 +0200181
182 ret = 0;
183 do_wakeup = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +0200184 page_nr = 0;
Jens Axboe5274f052006-03-30 15:15:30 +0200185
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200186 pipe_lock(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200187
Jens Axboe5274f052006-03-30 15:15:30 +0200188 for (;;) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200189 if (!pipe->readers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200190 send_sig(SIGPIPE, current, 0);
191 if (!ret)
192 ret = -EPIPE;
193 break;
194 }
195
Jens Axboe6f767b02006-04-11 13:53:56 +0200196 if (pipe->nrbufs < PIPE_BUFFERS) {
197 int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
Ingo Molnar3a326a22006-04-10 15:18:35 +0200198 struct pipe_buffer *buf = pipe->bufs + newbuf;
Jens Axboe5274f052006-03-30 15:15:30 +0200199
Jens Axboe912d35f2006-04-26 10:59:21 +0200200 buf->page = spd->pages[page_nr];
201 buf->offset = spd->partial[page_nr].offset;
202 buf->len = spd->partial[page_nr].len;
Jens Axboe497f9622007-06-11 12:00:45 +0200203 buf->private = spd->partial[page_nr].private;
Jens Axboe912d35f2006-04-26 10:59:21 +0200204 buf->ops = spd->ops;
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200205 if (spd->flags & SPLICE_F_GIFT)
206 buf->flags |= PIPE_BUF_FLAG_GIFT;
207
Jens Axboe6f767b02006-04-11 13:53:56 +0200208 pipe->nrbufs++;
Jens Axboe912d35f2006-04-26 10:59:21 +0200209 page_nr++;
210 ret += buf->len;
211
Jens Axboe6f767b02006-04-11 13:53:56 +0200212 if (pipe->inode)
213 do_wakeup = 1;
Jens Axboe5274f052006-03-30 15:15:30 +0200214
Jens Axboe912d35f2006-04-26 10:59:21 +0200215 if (!--spd->nr_pages)
Jens Axboe5274f052006-03-30 15:15:30 +0200216 break;
Jens Axboe6f767b02006-04-11 13:53:56 +0200217 if (pipe->nrbufs < PIPE_BUFFERS)
Jens Axboe5274f052006-03-30 15:15:30 +0200218 continue;
219
220 break;
221 }
222
Jens Axboe912d35f2006-04-26 10:59:21 +0200223 if (spd->flags & SPLICE_F_NONBLOCK) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700224 if (!ret)
225 ret = -EAGAIN;
226 break;
227 }
228
Jens Axboe5274f052006-03-30 15:15:30 +0200229 if (signal_pending(current)) {
230 if (!ret)
231 ret = -ERESTARTSYS;
232 break;
233 }
234
235 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200236 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200237 if (waitqueue_active(&pipe->wait))
238 wake_up_interruptible_sync(&pipe->wait);
239 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
Jens Axboe5274f052006-03-30 15:15:30 +0200240 do_wakeup = 0;
241 }
242
Ingo Molnar3a326a22006-04-10 15:18:35 +0200243 pipe->waiting_writers++;
244 pipe_wait(pipe);
245 pipe->waiting_writers--;
Jens Axboe5274f052006-03-30 15:15:30 +0200246 }
247
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200248 pipe_unlock(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200249
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200250 if (do_wakeup) {
251 smp_mb();
252 if (waitqueue_active(&pipe->wait))
253 wake_up_interruptible(&pipe->wait);
254 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
Jens Axboe5274f052006-03-30 15:15:30 +0200255 }
256
Jens Axboe00de00b2007-06-15 13:14:22 +0200257 while (page_nr < spd_pages)
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800258 spd->spd_release(spd, page_nr++);
Jens Axboe5274f052006-03-30 15:15:30 +0200259
260 return ret;
261}
262
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800263static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
264{
265 page_cache_release(spd->pages[i]);
266}
267
Ingo Molnar3a326a22006-04-10 15:18:35 +0200268static int
Jens Axboecbb7e572006-04-11 14:57:50 +0200269__generic_file_splice_read(struct file *in, loff_t *ppos,
270 struct pipe_inode_info *pipe, size_t len,
271 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200272{
273 struct address_space *mapping = in->f_mapping;
Fengguang Wud8983912007-07-19 01:48:06 -0700274 unsigned int loff, nr_pages, req_pages;
Jens Axboe16c523d2006-04-10 09:03:58 +0200275 struct page *pages[PIPE_BUFFERS];
Jens Axboe912d35f2006-04-26 10:59:21 +0200276 struct partial_page partial[PIPE_BUFFERS];
Jens Axboe5274f052006-03-30 15:15:30 +0200277 struct page *page;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200278 pgoff_t index, end_index;
279 loff_t isize;
Jens Axboeeb207962006-04-27 11:05:22 +0200280 int error, page_nr;
Jens Axboe912d35f2006-04-26 10:59:21 +0200281 struct splice_pipe_desc spd = {
282 .pages = pages,
283 .partial = partial,
284 .flags = flags,
285 .ops = &page_cache_pipe_buf_ops,
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800286 .spd_release = spd_release_page,
Jens Axboe912d35f2006-04-26 10:59:21 +0200287 };
Jens Axboe5274f052006-03-30 15:15:30 +0200288
Jens Axboecbb7e572006-04-11 14:57:50 +0200289 index = *ppos >> PAGE_CACHE_SHIFT;
Jens Axboe912d35f2006-04-26 10:59:21 +0200290 loff = *ppos & ~PAGE_CACHE_MASK;
Fengguang Wud8983912007-07-19 01:48:06 -0700291 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
292 nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS);
Jens Axboe5274f052006-03-30 15:15:30 +0200293
294 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200295 * Lookup the (hopefully) full range of pages we need.
296 */
297 spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
Fengguang Wu431a4822007-07-19 01:48:05 -0700298 index += spd.nr_pages;
Jens Axboeeb207962006-04-27 11:05:22 +0200299
300 /*
301 * If find_get_pages_contig() returned fewer pages than we needed,
Fengguang Wu431a4822007-07-19 01:48:05 -0700302 * readahead/allocate the rest and fill in the holes.
Jens Axboeeb207962006-04-27 11:05:22 +0200303 */
Fengguang Wu431a4822007-07-19 01:48:05 -0700304 if (spd.nr_pages < nr_pages)
Rusty Russellcf914a72007-07-19 01:48:08 -0700305 page_cache_sync_readahead(mapping, &in->f_ra, in,
306 index, req_pages - spd.nr_pages);
Fengguang Wu431a4822007-07-19 01:48:05 -0700307
Jens Axboe932cc6d2007-06-21 13:10:21 +0200308 error = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200309 while (spd.nr_pages < nr_pages) {
310 /*
311 * Page could be there, find_get_pages_contig() breaks on
312 * the first hole.
313 */
314 page = find_get_page(mapping, index);
315 if (!page) {
Jens Axboee27dedd2006-05-01 19:59:54 +0200316 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200317 * page didn't exist, allocate one.
318 */
319 page = page_cache_alloc_cold(mapping);
320 if (!page)
321 break;
322
323 error = add_to_page_cache_lru(page, mapping, index,
Hugh Dickins4cd13502008-04-03 23:35:22 +0100324 mapping_gfp_mask(mapping));
Jens Axboeeb207962006-04-27 11:05:22 +0200325 if (unlikely(error)) {
326 page_cache_release(page);
Jens Axboea0548872006-05-03 10:58:22 +0200327 if (error == -EEXIST)
328 continue;
Jens Axboeeb207962006-04-27 11:05:22 +0200329 break;
330 }
331 /*
332 * add_to_page_cache() locks the page, unlock it
333 * to avoid convoluting the logic below even more.
334 */
335 unlock_page(page);
336 }
337
338 pages[spd.nr_pages++] = page;
339 index++;
340 }
341
342 /*
343 * Now loop over the map and see if we need to start IO on any
344 * pages, fill in the partial map, etc.
345 */
346 index = *ppos >> PAGE_CACHE_SHIFT;
347 nr_pages = spd.nr_pages;
348 spd.nr_pages = 0;
349 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
Jens Axboe82aa5d62006-04-20 13:05:48 +0200350 unsigned int this_len;
351
352 if (!len)
353 break;
354
355 /*
356 * this_len is the max we'll use from this page
357 */
Andrew Mortonba5f5d92006-04-25 15:33:34 +0200358 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
Jens Axboeeb207962006-04-27 11:05:22 +0200359 page = pages[page_nr];
Jens Axboe7480a902006-04-11 13:52:47 +0200360
Fengguang Wua08a1662007-07-19 01:48:03 -0700361 if (PageReadahead(page))
Rusty Russellcf914a72007-07-19 01:48:08 -0700362 page_cache_async_readahead(mapping, &in->f_ra, in,
Fengguang Wud8983912007-07-19 01:48:06 -0700363 page, index, req_pages - page_nr);
Fengguang Wua08a1662007-07-19 01:48:03 -0700364
Jens Axboe7480a902006-04-11 13:52:47 +0200365 /*
366 * If the page isn't uptodate, we may need to start io on it
367 */
368 if (!PageUptodate(page)) {
Jens Axboec4f895c2006-04-19 15:56:12 +0200369 /*
370 * If in nonblock mode then dont block on waiting
371 * for an in-flight io page
372 */
Fengguang Wu9ae9d682007-05-08 08:44:36 +0200373 if (flags & SPLICE_F_NONBLOCK) {
Nick Piggin529ae9a2008-08-02 12:01:03 +0200374 if (!trylock_page(page)) {
Jens Axboe8191ecd2008-04-10 08:24:25 +0200375 error = -EAGAIN;
Fengguang Wu9ae9d682007-05-08 08:44:36 +0200376 break;
Jens Axboe8191ecd2008-04-10 08:24:25 +0200377 }
Fengguang Wu9ae9d682007-05-08 08:44:36 +0200378 } else
379 lock_page(page);
Jens Axboe7480a902006-04-11 13:52:47 +0200380
381 /*
Miklos Szeredi32502b82008-07-04 09:35:17 +0200382 * Page was truncated, or invalidated by the
383 * filesystem. Redo the find/create, but this time the
384 * page is kept locked, so there's no chance of another
385 * race with truncate/invalidate.
Jens Axboe7480a902006-04-11 13:52:47 +0200386 */
387 if (!page->mapping) {
388 unlock_page(page);
Miklos Szeredi32502b82008-07-04 09:35:17 +0200389 page = find_or_create_page(mapping, index,
390 mapping_gfp_mask(mapping));
391
392 if (!page) {
393 error = -ENOMEM;
394 break;
395 }
396 page_cache_release(pages[page_nr]);
397 pages[page_nr] = page;
Jens Axboe7480a902006-04-11 13:52:47 +0200398 }
399 /*
400 * page was already under io and is now done, great
401 */
402 if (PageUptodate(page)) {
403 unlock_page(page);
404 goto fill_it;
405 }
406
Jens Axboe7480a902006-04-11 13:52:47 +0200407 /*
408 * need to read in the page
409 */
410 error = mapping->a_ops->readpage(in, page);
Jens Axboe7480a902006-04-11 13:52:47 +0200411 if (unlikely(error)) {
Jens Axboeeb207962006-04-27 11:05:22 +0200412 /*
413 * We really should re-lookup the page here,
414 * but it complicates things a lot. Instead
415 * lets just do what we already stored, and
416 * we'll get it the next time we are called.
417 */
Jens Axboe7480a902006-04-11 13:52:47 +0200418 if (error == AOP_TRUNCATED_PAGE)
Jens Axboeeb207962006-04-27 11:05:22 +0200419 error = 0;
420
Jens Axboe7480a902006-04-11 13:52:47 +0200421 break;
422 }
Jens Axboe620a3242007-06-07 09:39:42 +0200423 }
424fill_it:
425 /*
426 * i_size must be checked after PageUptodate.
427 */
428 isize = i_size_read(mapping->host);
429 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
430 if (unlikely(!isize || index > end_index))
431 break;
432
433 /*
434 * if this is the last page, see if we need to shrink
435 * the length and stop
436 */
437 if (end_index == index) {
438 unsigned int plen;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200439
440 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200441 * max good bytes in this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200442 */
Jens Axboe620a3242007-06-07 09:39:42 +0200443 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
444 if (plen <= loff)
Jens Axboe91ad66e2006-04-19 15:55:10 +0200445 break;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200446
447 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200448 * force quit after adding this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200449 */
Jens Axboe620a3242007-06-07 09:39:42 +0200450 this_len = min(this_len, plen - loff);
451 len = this_len;
Jens Axboe7480a902006-04-11 13:52:47 +0200452 }
Jens Axboe620a3242007-06-07 09:39:42 +0200453
Jens Axboeeb207962006-04-27 11:05:22 +0200454 partial[page_nr].offset = loff;
455 partial[page_nr].len = this_len;
Jens Axboe82aa5d62006-04-20 13:05:48 +0200456 len -= this_len;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200457 loff = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200458 spd.nr_pages++;
459 index++;
Jens Axboe5274f052006-03-30 15:15:30 +0200460 }
461
Jens Axboeeb207962006-04-27 11:05:22 +0200462 /*
Hugh Dickins475ecad2007-06-07 09:36:00 +0200463 * Release any pages at the end, if we quit early. 'page_nr' is how far
Jens Axboeeb207962006-04-27 11:05:22 +0200464 * we got, 'nr_pages' is how many pages are in the map.
465 */
466 while (page_nr < nr_pages)
467 page_cache_release(pages[page_nr++]);
Fengguang Wuf4e6b492007-10-16 01:24:33 -0700468 in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
Jens Axboeeb207962006-04-27 11:05:22 +0200469
Jens Axboe912d35f2006-04-26 10:59:21 +0200470 if (spd.nr_pages)
Jens Axboe00522fb2006-04-26 14:39:29 +0200471 return splice_to_pipe(pipe, &spd);
Jens Axboe5274f052006-03-30 15:15:30 +0200472
Jens Axboe7480a902006-04-11 13:52:47 +0200473 return error;
Jens Axboe5274f052006-03-30 15:15:30 +0200474}
475
Jens Axboe83f91352006-04-02 23:05:09 +0200476/**
477 * generic_file_splice_read - splice data from file to a pipe
478 * @in: file to splice from
Jens Axboe932cc6d2007-06-21 13:10:21 +0200479 * @ppos: position in @in
Jens Axboe83f91352006-04-02 23:05:09 +0200480 * @pipe: pipe to splice to
481 * @len: number of bytes to splice
482 * @flags: splice modifier flags
483 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200484 * Description:
485 * Will read pages from given file and fill them into a pipe. Can be
486 * used as long as the address_space operations for the source implements
487 * a readpage() hook.
488 *
Jens Axboe83f91352006-04-02 23:05:09 +0200489 */
Jens Axboecbb7e572006-04-11 14:57:50 +0200490ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
491 struct pipe_inode_info *pipe, size_t len,
492 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200493{
Jens Axboed366d3982007-06-01 14:54:11 +0200494 loff_t isize, left;
Jens Axboe8191ecd2008-04-10 08:24:25 +0200495 int ret;
Jens Axboed366d3982007-06-01 14:54:11 +0200496
497 isize = i_size_read(in->f_mapping->host);
498 if (unlikely(*ppos >= isize))
499 return 0;
500
501 left = isize - *ppos;
502 if (unlikely(left < len))
503 len = left;
Jens Axboe5274f052006-03-30 15:15:30 +0200504
Jens Axboe8191ecd2008-04-10 08:24:25 +0200505 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
Miklos Szeredi723590e2009-08-15 08:43:22 +0200506 if (ret > 0) {
Jens Axboecbb7e572006-04-11 14:57:50 +0200507 *ppos += ret;
Miklos Szeredi723590e2009-08-15 08:43:22 +0200508 file_accessed(in);
509 }
Jens Axboe5274f052006-03-30 15:15:30 +0200510
511 return ret;
512}
Jens Axboe059a8f32006-04-02 23:06:05 +0200513EXPORT_SYMBOL(generic_file_splice_read);
514
Miklos Szeredi68181732009-05-07 15:37:36 +0200515static const struct pipe_buf_operations default_pipe_buf_ops = {
516 .can_merge = 0,
517 .map = generic_pipe_buf_map,
518 .unmap = generic_pipe_buf_unmap,
519 .confirm = generic_pipe_buf_confirm,
520 .release = generic_pipe_buf_release,
521 .steal = generic_pipe_buf_steal,
522 .get = generic_pipe_buf_get,
523};
524
525static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
526 unsigned long vlen, loff_t offset)
527{
528 mm_segment_t old_fs;
529 loff_t pos = offset;
530 ssize_t res;
531
532 old_fs = get_fs();
533 set_fs(get_ds());
534 /* The cast to a user pointer is valid due to the set_fs() */
535 res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos);
536 set_fs(old_fs);
537
538 return res;
539}
540
Miklos Szeredib2858d72009-05-19 11:37:46 +0200541static ssize_t kernel_write(struct file *file, const char *buf, size_t count,
542 loff_t pos)
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200543{
544 mm_segment_t old_fs;
545 ssize_t res;
546
547 old_fs = get_fs();
548 set_fs(get_ds());
549 /* The cast to a user pointer is valid due to the set_fs() */
Miklos Szeredib2858d72009-05-19 11:37:46 +0200550 res = vfs_write(file, (const char __user *)buf, count, &pos);
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200551 set_fs(old_fs);
552
553 return res;
554}
555
Miklos Szeredi68181732009-05-07 15:37:36 +0200556ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
557 struct pipe_inode_info *pipe, size_t len,
558 unsigned int flags)
559{
560 unsigned int nr_pages;
561 unsigned int nr_freed;
562 size_t offset;
563 struct page *pages[PIPE_BUFFERS];
564 struct partial_page partial[PIPE_BUFFERS];
565 struct iovec vec[PIPE_BUFFERS];
566 pgoff_t index;
567 ssize_t res;
568 size_t this_len;
569 int error;
570 int i;
571 struct splice_pipe_desc spd = {
572 .pages = pages,
573 .partial = partial,
574 .flags = flags,
575 .ops = &default_pipe_buf_ops,
576 .spd_release = spd_release_page,
577 };
578
579 index = *ppos >> PAGE_CACHE_SHIFT;
580 offset = *ppos & ~PAGE_CACHE_MASK;
581 nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
582
583 for (i = 0; i < nr_pages && i < PIPE_BUFFERS && len; i++) {
584 struct page *page;
585
Jens Axboe4f231222009-05-13 08:35:35 +0200586 page = alloc_page(GFP_USER);
Miklos Szeredi68181732009-05-07 15:37:36 +0200587 error = -ENOMEM;
588 if (!page)
589 goto err;
590
591 this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset);
Jens Axboe4f231222009-05-13 08:35:35 +0200592 vec[i].iov_base = (void __user *) page_address(page);
Miklos Szeredi68181732009-05-07 15:37:36 +0200593 vec[i].iov_len = this_len;
594 pages[i] = page;
595 spd.nr_pages++;
596 len -= this_len;
597 offset = 0;
598 }
599
600 res = kernel_readv(in, vec, spd.nr_pages, *ppos);
Andrew Morton77f6bf52009-05-14 09:49:44 +0200601 if (res < 0) {
602 error = res;
Miklos Szeredi68181732009-05-07 15:37:36 +0200603 goto err;
Andrew Morton77f6bf52009-05-14 09:49:44 +0200604 }
Miklos Szeredi68181732009-05-07 15:37:36 +0200605
606 error = 0;
607 if (!res)
608 goto err;
609
610 nr_freed = 0;
611 for (i = 0; i < spd.nr_pages; i++) {
Miklos Szeredi68181732009-05-07 15:37:36 +0200612 this_len = min_t(size_t, vec[i].iov_len, res);
613 partial[i].offset = 0;
614 partial[i].len = this_len;
615 if (!this_len) {
616 __free_page(pages[i]);
617 pages[i] = NULL;
618 nr_freed++;
619 }
620 res -= this_len;
621 }
622 spd.nr_pages -= nr_freed;
623
624 res = splice_to_pipe(pipe, &spd);
625 if (res > 0)
626 *ppos += res;
627
628 return res;
629
630err:
Jens Axboe4f231222009-05-13 08:35:35 +0200631 for (i = 0; i < spd.nr_pages; i++)
Miklos Szeredi68181732009-05-07 15:37:36 +0200632 __free_page(pages[i]);
Jens Axboe4f231222009-05-13 08:35:35 +0200633
Miklos Szeredi68181732009-05-07 15:37:36 +0200634 return error;
635}
636EXPORT_SYMBOL(default_file_splice_read);
637
Jens Axboe5274f052006-03-30 15:15:30 +0200638/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200639 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
Jens Axboe016b6612006-04-25 15:42:00 +0200640 * using sendpage(). Return the number of bytes sent.
Jens Axboe5274f052006-03-30 15:15:30 +0200641 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200642static int pipe_to_sendpage(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +0200643 struct pipe_buffer *buf, struct splice_desc *sd)
644{
Jens Axboe6a14b902007-06-14 13:08:55 +0200645 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200646 loff_t pos = sd->pos;
Jens Axboef84d7512006-05-01 19:59:03 +0200647 int ret, more;
Jens Axboe5274f052006-03-30 15:15:30 +0200648
Jens Axboecac36bb2007-06-14 13:10:48 +0200649 ret = buf->ops->confirm(pipe, buf);
Jens Axboef84d7512006-05-01 19:59:03 +0200650 if (!ret) {
651 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
Changli Gaocc56f7d2009-11-04 09:09:52 +0100652 if (file->f_op && file->f_op->sendpage)
653 ret = file->f_op->sendpage(file, buf->page, buf->offset,
654 sd->len, &pos, more);
655 else
656 ret = -EINVAL;
Jens Axboef84d7512006-05-01 19:59:03 +0200657 }
Jens Axboe5274f052006-03-30 15:15:30 +0200658
Jens Axboe016b6612006-04-25 15:42:00 +0200659 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200660}
661
662/*
663 * This is a little more tricky than the file -> pipe splicing. There are
664 * basically three cases:
665 *
666 * - Destination page already exists in the address space and there
667 * are users of it. For that case we have no other option that
668 * copying the data. Tough luck.
669 * - Destination page already exists in the address space, but there
670 * are no users of it. Make sure it's uptodate, then drop it. Fall
671 * through to last case.
672 * - Destination page does not exist, we can add the pipe page to
673 * the page cache and avoid the copy.
674 *
Jens Axboe83f91352006-04-02 23:05:09 +0200675 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
676 * sd->flags), we attempt to migrate pages from the pipe to the output
677 * file address space page cache. This is possible if no one else has
678 * the pipe page referenced outside of the pipe and page cache. If
679 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
680 * a new page in the output file page cache and fill/dirty that.
Jens Axboe5274f052006-03-30 15:15:30 +0200681 */
Miklos Szeredi328eaab2009-04-14 19:48:39 +0200682int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
683 struct splice_desc *sd)
Jens Axboe5274f052006-03-30 15:15:30 +0200684{
Jens Axboe6a14b902007-06-14 13:08:55 +0200685 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200686 struct address_space *mapping = file->f_mapping;
Jens Axboe016b6612006-04-25 15:42:00 +0200687 unsigned int offset, this_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200688 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -0700689 void *fsdata;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200690 int ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200691
692 /*
Jens Axboe49d0b212006-04-10 09:04:41 +0200693 * make sure the data in this buffer is uptodate
Jens Axboe5274f052006-03-30 15:15:30 +0200694 */
Jens Axboecac36bb2007-06-14 13:10:48 +0200695 ret = buf->ops->confirm(pipe, buf);
Jens Axboef84d7512006-05-01 19:59:03 +0200696 if (unlikely(ret))
697 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200698
Jens Axboe5274f052006-03-30 15:15:30 +0200699 offset = sd->pos & ~PAGE_CACHE_MASK;
700
Jens Axboe016b6612006-04-25 15:42:00 +0200701 this_len = sd->len;
702 if (this_len + offset > PAGE_CACHE_SIZE)
703 this_len = PAGE_CACHE_SIZE - offset;
704
Nick Pigginafddba42007-10-16 01:25:01 -0700705 ret = pagecache_write_begin(file, mapping, sd->pos, this_len,
706 AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
707 if (unlikely(ret))
708 goto out;
Jens Axboe5274f052006-03-30 15:15:30 +0200709
Jens Axboe0568b402006-05-01 19:50:48 +0200710 if (buf->page != page) {
Jens Axboef84d7512006-05-01 19:59:03 +0200711 /*
712 * Careful, ->map() uses KM_USER0!
713 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200714 char *src = buf->ops->map(pipe, buf, 1);
Jens Axboef84d7512006-05-01 19:59:03 +0200715 char *dst = kmap_atomic(page, KM_USER1);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200716
Jens Axboe016b6612006-04-25 15:42:00 +0200717 memcpy(dst + offset, src + buf->offset, this_len);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200718 flush_dcache_page(page);
Jens Axboef84d7512006-05-01 19:59:03 +0200719 kunmap_atomic(dst, KM_USER1);
Jens Axboe76ad4d12006-05-03 10:41:33 +0200720 buf->ops->unmap(pipe, buf, src);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200721 }
Nick Pigginafddba42007-10-16 01:25:01 -0700722 ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len,
723 page, fsdata);
Jens Axboe5274f052006-03-30 15:15:30 +0200724out:
Jens Axboe5274f052006-03-30 15:15:30 +0200725 return ret;
726}
Miklos Szeredi328eaab2009-04-14 19:48:39 +0200727EXPORT_SYMBOL(pipe_to_file);
Jens Axboe5274f052006-03-30 15:15:30 +0200728
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200729static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
730{
731 smp_mb();
732 if (waitqueue_active(&pipe->wait))
733 wake_up_interruptible(&pipe->wait);
734 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
735}
736
737/**
738 * splice_from_pipe_feed - feed available data from a pipe to a file
739 * @pipe: pipe to splice from
740 * @sd: information to @actor
741 * @actor: handler that splices the data
742 *
743 * Description:
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200744 * This function loops over the pipe and calls @actor to do the
745 * actual moving of a single struct pipe_buffer to the desired
746 * destination. It returns when there's no more buffers left in
747 * the pipe or if the requested number of bytes (@sd->total_len)
748 * have been copied. It returns a positive number (one) if the
749 * pipe needs to be filled with more data, zero if the required
750 * number of bytes have been copied and -errno on error.
751 *
752 * This, together with splice_from_pipe_{begin,end,next}, may be
753 * used to implement the functionality of __splice_from_pipe() when
754 * locking is required around copying the pipe buffers to the
755 * destination.
756 */
757int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
758 splice_actor *actor)
759{
760 int ret;
761
762 while (pipe->nrbufs) {
763 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
764 const struct pipe_buf_operations *ops = buf->ops;
765
766 sd->len = buf->len;
767 if (sd->len > sd->total_len)
768 sd->len = sd->total_len;
769
770 ret = actor(pipe, buf, sd);
771 if (ret <= 0) {
772 if (ret == -ENODATA)
773 ret = 0;
774 return ret;
775 }
776 buf->offset += ret;
777 buf->len -= ret;
778
779 sd->num_spliced += ret;
780 sd->len -= ret;
781 sd->pos += ret;
782 sd->total_len -= ret;
783
784 if (!buf->len) {
785 buf->ops = NULL;
786 ops->release(pipe, buf);
787 pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
788 pipe->nrbufs--;
789 if (pipe->inode)
790 sd->need_wakeup = true;
791 }
792
793 if (!sd->total_len)
794 return 0;
795 }
796
797 return 1;
798}
799EXPORT_SYMBOL(splice_from_pipe_feed);
800
801/**
802 * splice_from_pipe_next - wait for some data to splice from
803 * @pipe: pipe to splice from
804 * @sd: information about the splice operation
805 *
806 * Description:
807 * This function will wait for some data and return a positive
808 * value (one) if pipe buffers are available. It will return zero
809 * or -errno if no more data needs to be spliced.
810 */
811int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
812{
813 while (!pipe->nrbufs) {
814 if (!pipe->writers)
815 return 0;
816
817 if (!pipe->waiting_writers && sd->num_spliced)
818 return 0;
819
820 if (sd->flags & SPLICE_F_NONBLOCK)
821 return -EAGAIN;
822
823 if (signal_pending(current))
824 return -ERESTARTSYS;
825
826 if (sd->need_wakeup) {
827 wakeup_pipe_writers(pipe);
828 sd->need_wakeup = false;
829 }
830
831 pipe_wait(pipe);
832 }
833
834 return 1;
835}
836EXPORT_SYMBOL(splice_from_pipe_next);
837
838/**
839 * splice_from_pipe_begin - start splicing from pipe
Randy Dunlapb80901b2009-04-16 19:09:55 -0700840 * @sd: information about the splice operation
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200841 *
842 * Description:
843 * This function should be called before a loop containing
844 * splice_from_pipe_next() and splice_from_pipe_feed() to
845 * initialize the necessary fields of @sd.
846 */
847void splice_from_pipe_begin(struct splice_desc *sd)
848{
849 sd->num_spliced = 0;
850 sd->need_wakeup = false;
851}
852EXPORT_SYMBOL(splice_from_pipe_begin);
853
854/**
855 * splice_from_pipe_end - finish splicing from pipe
856 * @pipe: pipe to splice from
857 * @sd: information about the splice operation
858 *
859 * Description:
860 * This function will wake up pipe writers if necessary. It should
861 * be called after a loop containing splice_from_pipe_next() and
862 * splice_from_pipe_feed().
863 */
864void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
865{
866 if (sd->need_wakeup)
867 wakeup_pipe_writers(pipe);
868}
869EXPORT_SYMBOL(splice_from_pipe_end);
870
Jens Axboe932cc6d2007-06-21 13:10:21 +0200871/**
872 * __splice_from_pipe - splice data from a pipe to given actor
873 * @pipe: pipe to splice from
874 * @sd: information to @actor
875 * @actor: handler that splices the data
876 *
877 * Description:
878 * This function does little more than loop over the pipe and call
879 * @actor to do the actual moving of a single struct pipe_buffer to
880 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
881 * pipe_to_user.
882 *
Jens Axboe83f91352006-04-02 23:05:09 +0200883 */
Jens Axboec66ab6f2007-06-12 21:17:17 +0200884ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
885 splice_actor *actor)
Jens Axboe5274f052006-03-30 15:15:30 +0200886{
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200887 int ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200888
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200889 splice_from_pipe_begin(sd);
890 do {
891 ret = splice_from_pipe_next(pipe, sd);
892 if (ret > 0)
893 ret = splice_from_pipe_feed(pipe, sd, actor);
894 } while (ret > 0);
895 splice_from_pipe_end(pipe, sd);
Jens Axboe5274f052006-03-30 15:15:30 +0200896
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200897 return sd->num_spliced ? sd->num_spliced : ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200898}
Mark Fasheh40bee442007-03-21 13:11:02 +0100899EXPORT_SYMBOL(__splice_from_pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200900
Jens Axboe932cc6d2007-06-21 13:10:21 +0200901/**
902 * splice_from_pipe - splice data from a pipe to a file
903 * @pipe: pipe to splice from
904 * @out: file to splice to
905 * @ppos: position in @out
906 * @len: how many bytes to splice
907 * @flags: splice modifier flags
908 * @actor: handler that splices the data
909 *
910 * Description:
Miklos Szeredi29339702009-04-14 19:48:37 +0200911 * See __splice_from_pipe. This function locks the pipe inode,
Jens Axboe932cc6d2007-06-21 13:10:21 +0200912 * otherwise it's identical to __splice_from_pipe().
913 *
914 */
Mark Fasheh6da61802006-10-17 18:43:07 +0200915ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
916 loff_t *ppos, size_t len, unsigned int flags,
917 splice_actor *actor)
918{
919 ssize_t ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200920 struct splice_desc sd = {
921 .total_len = len,
922 .flags = flags,
923 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +0200924 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +0200925 };
Mark Fasheh6da61802006-10-17 18:43:07 +0200926
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200927 pipe_lock(pipe);
Jens Axboec66ab6f2007-06-12 21:17:17 +0200928 ret = __splice_from_pipe(pipe, &sd, actor);
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200929 pipe_unlock(pipe);
Mark Fasheh6da61802006-10-17 18:43:07 +0200930
931 return ret;
932}
933
934/**
Jens Axboe83f91352006-04-02 23:05:09 +0200935 * generic_file_splice_write - splice data from a pipe to a file
Ingo Molnar3a326a22006-04-10 15:18:35 +0200936 * @pipe: pipe info
Jens Axboe83f91352006-04-02 23:05:09 +0200937 * @out: file to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +0200938 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +0200939 * @len: number of bytes to splice
940 * @flags: splice modifier flags
941 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200942 * Description:
943 * Will either move or copy pages (determined by @flags options) from
944 * the given pipe inode to the given file.
Jens Axboe83f91352006-04-02 23:05:09 +0200945 *
946 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200947ssize_t
948generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +0200949 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200950{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200951 struct address_space *mapping = out->f_mapping;
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200952 struct inode *inode = mapping->host;
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +0200953 struct splice_desc sd = {
954 .total_len = len,
955 .flags = flags,
956 .pos = *ppos,
957 .u.file = out,
958 };
Ingo Molnar3a326a22006-04-10 15:18:35 +0200959 ssize_t ret;
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200960
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200961 pipe_lock(pipe);
Miklos Szeredieb443e52009-04-14 19:48:38 +0200962
963 splice_from_pipe_begin(&sd);
964 do {
965 ret = splice_from_pipe_next(pipe, &sd);
966 if (ret <= 0)
967 break;
968
969 mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
970 ret = file_remove_suid(out);
Miklos Szeredi723590e2009-08-15 08:43:22 +0200971 if (!ret) {
972 file_update_time(out);
Miklos Szeredieb443e52009-04-14 19:48:38 +0200973 ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file);
Miklos Szeredi723590e2009-08-15 08:43:22 +0200974 }
Miklos Szeredieb443e52009-04-14 19:48:38 +0200975 mutex_unlock(&inode->i_mutex);
976 } while (ret > 0);
977 splice_from_pipe_end(pipe, &sd);
978
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200979 pipe_unlock(pipe);
Miklos Szeredieb443e52009-04-14 19:48:38 +0200980
981 if (sd.num_spliced)
982 ret = sd.num_spliced;
983
Jens Axboea4514eb2006-04-19 15:57:05 +0200984 if (ret > 0) {
Jens Axboe17ee4f42007-06-15 13:10:37 +0200985 unsigned long nr_pages;
Jan Kara148f9482009-08-17 19:52:36 +0200986 int err;
Jens Axboe17ee4f42007-06-15 13:10:37 +0200987
Jens Axboe17ee4f42007-06-15 13:10:37 +0200988 nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200989
Jan Kara148f9482009-08-17 19:52:36 +0200990 err = generic_write_sync(out, *ppos, ret);
991 if (err)
992 ret = err;
993 else
994 *ppos += ret;
Jens Axboe17ee4f42007-06-15 13:10:37 +0200995 balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200996 }
997
998 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200999}
1000
Jens Axboe059a8f32006-04-02 23:06:05 +02001001EXPORT_SYMBOL(generic_file_splice_write);
1002
Miklos Szeredib2858d72009-05-19 11:37:46 +02001003static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1004 struct splice_desc *sd)
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001005{
Miklos Szeredib2858d72009-05-19 11:37:46 +02001006 int ret;
1007 void *data;
1008
1009 ret = buf->ops->confirm(pipe, buf);
1010 if (ret)
1011 return ret;
1012
1013 data = buf->ops->map(pipe, buf, 0);
1014 ret = kernel_write(sd->u.file, data + buf->offset, sd->len, sd->pos);
1015 buf->ops->unmap(pipe, buf, data);
1016
1017 return ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001018}
1019
1020static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
1021 struct file *out, loff_t *ppos,
1022 size_t len, unsigned int flags)
1023{
Miklos Szeredib2858d72009-05-19 11:37:46 +02001024 ssize_t ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001025
Miklos Szeredib2858d72009-05-19 11:37:46 +02001026 ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
1027 if (ret > 0)
1028 *ppos += ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001029
Miklos Szeredib2858d72009-05-19 11:37:46 +02001030 return ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001031}
1032
Jens Axboe83f91352006-04-02 23:05:09 +02001033/**
1034 * generic_splice_sendpage - splice data from a pipe to a socket
Jens Axboe932cc6d2007-06-21 13:10:21 +02001035 * @pipe: pipe to splice from
Jens Axboe83f91352006-04-02 23:05:09 +02001036 * @out: socket to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +02001037 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +02001038 * @len: number of bytes to splice
1039 * @flags: splice modifier flags
1040 *
Jens Axboe932cc6d2007-06-21 13:10:21 +02001041 * Description:
1042 * Will send @len bytes from the pipe to a network socket. No data copying
1043 * is involved.
Jens Axboe83f91352006-04-02 23:05:09 +02001044 *
1045 */
Ingo Molnar3a326a22006-04-10 15:18:35 +02001046ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +02001047 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001048{
Jens Axboe00522fb2006-04-26 14:39:29 +02001049 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
Jens Axboe5274f052006-03-30 15:15:30 +02001050}
1051
Jens Axboe059a8f32006-04-02 23:06:05 +02001052EXPORT_SYMBOL(generic_splice_sendpage);
Jeff Garzika0f06782006-03-30 23:06:13 -05001053
Jens Axboe83f91352006-04-02 23:05:09 +02001054/*
1055 * Attempt to initiate a splice from pipe to file.
1056 */
Ingo Molnar3a326a22006-04-10 15:18:35 +02001057static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +02001058 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001059{
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001060 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
1061 loff_t *, size_t, unsigned int);
Jens Axboe5274f052006-03-30 15:15:30 +02001062 int ret;
1063
Jens Axboe49570e92006-04-11 13:56:09 +02001064 if (unlikely(!(out->f_mode & FMODE_WRITE)))
Jens Axboe5274f052006-03-30 15:15:30 +02001065 return -EBADF;
1066
Linus Torvaldsefc968d2008-10-09 14:04:54 -07001067 if (unlikely(out->f_flags & O_APPEND))
1068 return -EINVAL;
1069
Jens Axboecbb7e572006-04-11 14:57:50 +02001070 ret = rw_verify_area(WRITE, out, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +02001071 if (unlikely(ret < 0))
1072 return ret;
1073
Changli Gaocc56f7d2009-11-04 09:09:52 +01001074 if (out->f_op && out->f_op->splice_write)
1075 splice_write = out->f_op->splice_write;
1076 else
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001077 splice_write = default_file_splice_write;
1078
1079 return splice_write(pipe, out, ppos, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001080}
1081
Jens Axboe83f91352006-04-02 23:05:09 +02001082/*
1083 * Attempt to initiate a splice from a file to a pipe.
1084 */
Jens Axboecbb7e572006-04-11 14:57:50 +02001085static long do_splice_to(struct file *in, loff_t *ppos,
1086 struct pipe_inode_info *pipe, size_t len,
1087 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001088{
Miklos Szeredi68181732009-05-07 15:37:36 +02001089 ssize_t (*splice_read)(struct file *, loff_t *,
1090 struct pipe_inode_info *, size_t, unsigned int);
Jens Axboe5274f052006-03-30 15:15:30 +02001091 int ret;
1092
Jens Axboe49570e92006-04-11 13:56:09 +02001093 if (unlikely(!(in->f_mode & FMODE_READ)))
Jens Axboe5274f052006-03-30 15:15:30 +02001094 return -EBADF;
1095
Jens Axboecbb7e572006-04-11 14:57:50 +02001096 ret = rw_verify_area(READ, in, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +02001097 if (unlikely(ret < 0))
1098 return ret;
1099
Changli Gaocc56f7d2009-11-04 09:09:52 +01001100 if (in->f_op && in->f_op->splice_read)
1101 splice_read = in->f_op->splice_read;
1102 else
Miklos Szeredi68181732009-05-07 15:37:36 +02001103 splice_read = default_file_splice_read;
1104
1105 return splice_read(in, ppos, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001106}
1107
Jens Axboe932cc6d2007-06-21 13:10:21 +02001108/**
1109 * splice_direct_to_actor - splices data directly between two non-pipes
1110 * @in: file to splice from
1111 * @sd: actor information on where to splice to
1112 * @actor: handles the data splicing
1113 *
1114 * Description:
1115 * This is a special case helper to splice directly between two
1116 * points, without requiring an explicit pipe. Internally an allocated
Randy Dunlap79685b82007-07-27 08:08:51 +02001117 * pipe is cached in the process, and reused during the lifetime of
Jens Axboe932cc6d2007-06-21 13:10:21 +02001118 * that process.
1119 *
Jens Axboec66ab6f2007-06-12 21:17:17 +02001120 */
1121ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
1122 splice_direct_actor *actor)
Jens Axboeb92ce552006-04-11 13:52:07 +02001123{
1124 struct pipe_inode_info *pipe;
1125 long ret, bytes;
1126 umode_t i_mode;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001127 size_t len;
1128 int i, flags;
Jens Axboeb92ce552006-04-11 13:52:07 +02001129
1130 /*
1131 * We require the input being a regular file, as we don't want to
1132 * randomly drop data for eg socket -> socket splicing. Use the
1133 * piped splicing for that!
1134 */
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001135 i_mode = in->f_path.dentry->d_inode->i_mode;
Jens Axboeb92ce552006-04-11 13:52:07 +02001136 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
1137 return -EINVAL;
1138
1139 /*
1140 * neither in nor out is a pipe, setup an internal pipe attached to
1141 * 'out' and transfer the wanted data from 'in' to 'out' through that
1142 */
1143 pipe = current->splice_pipe;
Jens Axboe49570e92006-04-11 13:56:09 +02001144 if (unlikely(!pipe)) {
Jens Axboeb92ce552006-04-11 13:52:07 +02001145 pipe = alloc_pipe_info(NULL);
1146 if (!pipe)
1147 return -ENOMEM;
1148
1149 /*
1150 * We don't have an immediate reader, but we'll read the stuff
Jens Axboe00522fb2006-04-26 14:39:29 +02001151 * out of the pipe right after the splice_to_pipe(). So set
Jens Axboeb92ce552006-04-11 13:52:07 +02001152 * PIPE_READERS appropriately.
1153 */
1154 pipe->readers = 1;
1155
1156 current->splice_pipe = pipe;
1157 }
1158
1159 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +02001160 * Do the splice.
Jens Axboeb92ce552006-04-11 13:52:07 +02001161 */
1162 ret = 0;
1163 bytes = 0;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001164 len = sd->total_len;
1165 flags = sd->flags;
1166
1167 /*
1168 * Don't block on output, we have to drain the direct pipe.
1169 */
1170 sd->flags &= ~SPLICE_F_NONBLOCK;
Jens Axboeb92ce552006-04-11 13:52:07 +02001171
1172 while (len) {
Jens Axboe51a92c02007-07-13 14:11:43 +02001173 size_t read_len;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001174 loff_t pos = sd->pos, prev_pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001175
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001176 ret = do_splice_to(in, &pos, pipe, len, flags);
Jens Axboe51a92c02007-07-13 14:11:43 +02001177 if (unlikely(ret <= 0))
Jens Axboeb92ce552006-04-11 13:52:07 +02001178 goto out_release;
1179
1180 read_len = ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001181 sd->total_len = read_len;
Jens Axboeb92ce552006-04-11 13:52:07 +02001182
1183 /*
1184 * NOTE: nonblocking mode only applies to the input. We
1185 * must not do the output in nonblocking mode as then we
1186 * could get stuck data in the internal pipe:
1187 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001188 ret = actor(pipe, sd);
Tom Zanussia82c53a2008-05-09 13:28:36 +02001189 if (unlikely(ret <= 0)) {
1190 sd->pos = prev_pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001191 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001192 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001193
1194 bytes += ret;
1195 len -= ret;
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001196 sd->pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001197
Tom Zanussia82c53a2008-05-09 13:28:36 +02001198 if (ret < read_len) {
1199 sd->pos = prev_pos + ret;
Jens Axboe51a92c02007-07-13 14:11:43 +02001200 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001201 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001202 }
1203
Jens Axboe9e971982008-01-29 21:05:57 +01001204done:
Jens Axboeb92ce552006-04-11 13:52:07 +02001205 pipe->nrbufs = pipe->curbuf = 0;
Jens Axboe80848702008-01-30 12:24:48 +01001206 file_accessed(in);
Jens Axboeb92ce552006-04-11 13:52:07 +02001207 return bytes;
1208
1209out_release:
1210 /*
1211 * If we did an incomplete transfer we must release
1212 * the pipe buffers in question:
1213 */
1214 for (i = 0; i < PIPE_BUFFERS; i++) {
1215 struct pipe_buffer *buf = pipe->bufs + i;
1216
1217 if (buf->ops) {
1218 buf->ops->release(pipe, buf);
1219 buf->ops = NULL;
1220 }
1221 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001222
Jens Axboe9e971982008-01-29 21:05:57 +01001223 if (!bytes)
1224 bytes = ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001225
Jens Axboe9e971982008-01-29 21:05:57 +01001226 goto done;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001227}
1228EXPORT_SYMBOL(splice_direct_to_actor);
1229
1230static int direct_splice_actor(struct pipe_inode_info *pipe,
1231 struct splice_desc *sd)
1232{
Jens Axboe6a14b902007-06-14 13:08:55 +02001233 struct file *file = sd->u.file;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001234
1235 return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
1236}
1237
Jens Axboe932cc6d2007-06-21 13:10:21 +02001238/**
1239 * do_splice_direct - splices data directly between two files
1240 * @in: file to splice from
1241 * @ppos: input file offset
1242 * @out: file to splice to
1243 * @len: number of bytes to splice
1244 * @flags: splice modifier flags
1245 *
1246 * Description:
1247 * For use by do_sendfile(). splice can easily emulate sendfile, but
1248 * doing it in the application would incur an extra system call
1249 * (splice in + splice out, as compared to just sendfile()). So this helper
1250 * can splice directly through a process-private pipe.
1251 *
1252 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001253long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
1254 size_t len, unsigned int flags)
1255{
1256 struct splice_desc sd = {
1257 .len = len,
1258 .total_len = len,
1259 .flags = flags,
1260 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +02001261 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +02001262 };
Jens Axboe51a92c02007-07-13 14:11:43 +02001263 long ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001264
1265 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
Jens Axboe51a92c02007-07-13 14:11:43 +02001266 if (ret > 0)
Tom Zanussia82c53a2008-05-09 13:28:36 +02001267 *ppos = sd.pos;
Jens Axboe51a92c02007-07-13 14:11:43 +02001268
Jens Axboec66ab6f2007-06-12 21:17:17 +02001269 return ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001270}
1271
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001272static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1273 struct pipe_inode_info *opipe,
1274 size_t len, unsigned int flags);
Jens Axboe83f91352006-04-02 23:05:09 +02001275/*
Jens Axboeddac0d32006-11-04 12:49:32 +01001276 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1277 * location, so checking ->i_pipe is not enough to verify that this is a
1278 * pipe.
1279 */
1280static inline struct pipe_inode_info *pipe_info(struct inode *inode)
1281{
1282 if (S_ISFIFO(inode->i_mode))
1283 return inode->i_pipe;
1284
1285 return NULL;
1286}
1287
1288/*
Jens Axboe83f91352006-04-02 23:05:09 +02001289 * Determine where to splice to/from.
1290 */
Ingo Molnar529565d2006-04-10 15:18:58 +02001291static long do_splice(struct file *in, loff_t __user *off_in,
1292 struct file *out, loff_t __user *off_out,
1293 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001294{
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001295 struct pipe_inode_info *ipipe;
1296 struct pipe_inode_info *opipe;
Jens Axboecbb7e572006-04-11 14:57:50 +02001297 loff_t offset, *off;
Jens Axboea4514eb2006-04-19 15:57:05 +02001298 long ret;
Jens Axboe5274f052006-03-30 15:15:30 +02001299
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001300 ipipe = pipe_info(in->f_path.dentry->d_inode);
1301 opipe = pipe_info(out->f_path.dentry->d_inode);
1302
1303 if (ipipe && opipe) {
1304 if (off_in || off_out)
1305 return -ESPIPE;
1306
1307 if (!(in->f_mode & FMODE_READ))
1308 return -EBADF;
1309
1310 if (!(out->f_mode & FMODE_WRITE))
1311 return -EBADF;
1312
1313 /* Splicing to self would be fun, but... */
1314 if (ipipe == opipe)
1315 return -EINVAL;
1316
1317 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1318 }
1319
1320 if (ipipe) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001321 if (off_in)
1322 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001323 if (off_out) {
Changli Gaocc56f7d2009-11-04 09:09:52 +01001324 if (!out->f_op || !out->f_op->llseek ||
1325 out->f_op->llseek == no_llseek)
Jens Axboeb92ce552006-04-11 13:52:07 +02001326 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001327 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001328 return -EFAULT;
Jens Axboecbb7e572006-04-11 14:57:50 +02001329 off = &offset;
1330 } else
1331 off = &out->f_pos;
Ingo Molnar529565d2006-04-10 15:18:58 +02001332
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001333 ret = do_splice_from(ipipe, out, off, len, flags);
Jens Axboea4514eb2006-04-19 15:57:05 +02001334
1335 if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
1336 ret = -EFAULT;
1337
1338 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001339 }
Jens Axboe5274f052006-03-30 15:15:30 +02001340
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001341 if (opipe) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001342 if (off_out)
1343 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001344 if (off_in) {
Changli Gaocc56f7d2009-11-04 09:09:52 +01001345 if (!in->f_op || !in->f_op->llseek ||
1346 in->f_op->llseek == no_llseek)
Jens Axboeb92ce552006-04-11 13:52:07 +02001347 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001348 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001349 return -EFAULT;
Jens Axboecbb7e572006-04-11 14:57:50 +02001350 off = &offset;
1351 } else
1352 off = &in->f_pos;
Ingo Molnar529565d2006-04-10 15:18:58 +02001353
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001354 ret = do_splice_to(in, off, opipe, len, flags);
Jens Axboea4514eb2006-04-19 15:57:05 +02001355
1356 if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
1357 ret = -EFAULT;
1358
1359 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001360 }
Jens Axboe5274f052006-03-30 15:15:30 +02001361
1362 return -EINVAL;
1363}
1364
Jens Axboe912d35f2006-04-26 10:59:21 +02001365/*
1366 * Map an iov into an array of pages and offset/length tupples. With the
1367 * partial_page structure, we can map several non-contiguous ranges into
1368 * our ones pages[] map instead of splitting that operation into pieces.
1369 * Could easily be exported as a generic helper for other users, in which
1370 * case one would probably want to add a 'max_nr_pages' parameter as well.
1371 */
1372static int get_iovec_page_array(const struct iovec __user *iov,
1373 unsigned int nr_vecs, struct page **pages,
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001374 struct partial_page *partial, int aligned)
Jens Axboe912d35f2006-04-26 10:59:21 +02001375{
1376 int buffers = 0, error = 0;
1377
Jens Axboe912d35f2006-04-26 10:59:21 +02001378 while (nr_vecs) {
1379 unsigned long off, npages;
Linus Torvalds75723952007-10-01 13:17:28 -07001380 struct iovec entry;
Jens Axboe912d35f2006-04-26 10:59:21 +02001381 void __user *base;
1382 size_t len;
1383 int i;
1384
Linus Torvalds75723952007-10-01 13:17:28 -07001385 error = -EFAULT;
Nick Pigginbc40d732008-07-25 19:45:26 -07001386 if (copy_from_user(&entry, iov, sizeof(entry)))
Jens Axboe912d35f2006-04-26 10:59:21 +02001387 break;
Linus Torvalds75723952007-10-01 13:17:28 -07001388
1389 base = entry.iov_base;
1390 len = entry.iov_len;
Jens Axboe912d35f2006-04-26 10:59:21 +02001391
1392 /*
1393 * Sanity check this iovec. 0 read succeeds.
1394 */
Linus Torvalds75723952007-10-01 13:17:28 -07001395 error = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +02001396 if (unlikely(!len))
1397 break;
1398 error = -EFAULT;
Bastian Blank712a30e2008-02-10 16:47:57 +02001399 if (!access_ok(VERIFY_READ, base, len))
Jens Axboe912d35f2006-04-26 10:59:21 +02001400 break;
1401
1402 /*
1403 * Get this base offset and number of pages, then map
1404 * in the user pages.
1405 */
1406 off = (unsigned long) base & ~PAGE_MASK;
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001407
1408 /*
1409 * If asked for alignment, the offset must be zero and the
1410 * length a multiple of the PAGE_SIZE.
1411 */
1412 error = -EINVAL;
1413 if (aligned && (off || len & ~PAGE_MASK))
1414 break;
1415
Jens Axboe912d35f2006-04-26 10:59:21 +02001416 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1417 if (npages > PIPE_BUFFERS - buffers)
1418 npages = PIPE_BUFFERS - buffers;
1419
Nick Pigginbc40d732008-07-25 19:45:26 -07001420 error = get_user_pages_fast((unsigned long)base, npages,
1421 0, &pages[buffers]);
Jens Axboe912d35f2006-04-26 10:59:21 +02001422
1423 if (unlikely(error <= 0))
1424 break;
1425
1426 /*
1427 * Fill this contiguous range into the partial page map.
1428 */
1429 for (i = 0; i < error; i++) {
Jens Axboe75914892006-05-02 12:57:18 +02001430 const int plen = min_t(size_t, len, PAGE_SIZE - off);
Jens Axboe912d35f2006-04-26 10:59:21 +02001431
1432 partial[buffers].offset = off;
1433 partial[buffers].len = plen;
1434
1435 off = 0;
1436 len -= plen;
1437 buffers++;
1438 }
1439
1440 /*
1441 * We didn't complete this iov, stop here since it probably
1442 * means we have to move some of this into a pipe to
1443 * be able to continue.
1444 */
1445 if (len)
1446 break;
1447
1448 /*
1449 * Don't continue if we mapped fewer pages than we asked for,
1450 * or if we mapped the max number of pages that we have
1451 * room for.
1452 */
1453 if (error < npages || buffers == PIPE_BUFFERS)
1454 break;
1455
1456 nr_vecs--;
1457 iov++;
1458 }
1459
Jens Axboe912d35f2006-04-26 10:59:21 +02001460 if (buffers)
1461 return buffers;
1462
1463 return error;
1464}
1465
Jens Axboe6a14b902007-06-14 13:08:55 +02001466static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1467 struct splice_desc *sd)
1468{
1469 char *src;
1470 int ret;
1471
Jens Axboecac36bb2007-06-14 13:10:48 +02001472 ret = buf->ops->confirm(pipe, buf);
Jens Axboe6a14b902007-06-14 13:08:55 +02001473 if (unlikely(ret))
1474 return ret;
1475
1476 /*
1477 * See if we can use the atomic maps, by prefaulting in the
1478 * pages and doing an atomic copy
1479 */
1480 if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) {
1481 src = buf->ops->map(pipe, buf, 1);
1482 ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset,
1483 sd->len);
1484 buf->ops->unmap(pipe, buf, src);
1485 if (!ret) {
1486 ret = sd->len;
1487 goto out;
1488 }
1489 }
1490
1491 /*
1492 * No dice, use slow non-atomic map and copy
1493 */
1494 src = buf->ops->map(pipe, buf, 0);
1495
1496 ret = sd->len;
1497 if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len))
1498 ret = -EFAULT;
1499
Jens Axboe6866bef2007-10-16 10:01:29 +02001500 buf->ops->unmap(pipe, buf, src);
Jens Axboe6a14b902007-06-14 13:08:55 +02001501out:
1502 if (ret > 0)
1503 sd->u.userptr += ret;
Jens Axboe6a14b902007-06-14 13:08:55 +02001504 return ret;
1505}
1506
1507/*
1508 * For lack of a better implementation, implement vmsplice() to userspace
1509 * as a simple copy of the pipes pages to the user iov.
1510 */
1511static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
1512 unsigned long nr_segs, unsigned int flags)
1513{
1514 struct pipe_inode_info *pipe;
1515 struct splice_desc sd;
1516 ssize_t size;
1517 int error;
1518 long ret;
1519
1520 pipe = pipe_info(file->f_path.dentry->d_inode);
1521 if (!pipe)
1522 return -EBADF;
1523
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001524 pipe_lock(pipe);
Jens Axboe6a14b902007-06-14 13:08:55 +02001525
1526 error = ret = 0;
1527 while (nr_segs) {
1528 void __user *base;
1529 size_t len;
1530
1531 /*
1532 * Get user address base and length for this iovec.
1533 */
1534 error = get_user(base, &iov->iov_base);
1535 if (unlikely(error))
1536 break;
1537 error = get_user(len, &iov->iov_len);
1538 if (unlikely(error))
1539 break;
1540
1541 /*
1542 * Sanity check this iovec. 0 read succeeds.
1543 */
1544 if (unlikely(!len))
1545 break;
1546 if (unlikely(!base)) {
1547 error = -EFAULT;
1548 break;
1549 }
1550
Jens Axboe88119302008-02-08 08:49:14 -08001551 if (unlikely(!access_ok(VERIFY_WRITE, base, len))) {
1552 error = -EFAULT;
1553 break;
1554 }
1555
Jens Axboe6a14b902007-06-14 13:08:55 +02001556 sd.len = 0;
1557 sd.total_len = len;
1558 sd.flags = flags;
1559 sd.u.userptr = base;
1560 sd.pos = 0;
1561
1562 size = __splice_from_pipe(pipe, &sd, pipe_to_user);
1563 if (size < 0) {
1564 if (!ret)
1565 ret = size;
1566
1567 break;
1568 }
1569
1570 ret += size;
1571
1572 if (size < len)
1573 break;
1574
1575 nr_segs--;
1576 iov++;
1577 }
1578
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001579 pipe_unlock(pipe);
Jens Axboe6a14b902007-06-14 13:08:55 +02001580
1581 if (!ret)
1582 ret = error;
1583
1584 return ret;
1585}
1586
Jens Axboe912d35f2006-04-26 10:59:21 +02001587/*
1588 * vmsplice splices a user address range into a pipe. It can be thought of
1589 * as splice-from-memory, where the regular splice is splice-from-file (or
1590 * to file). In both cases the output is a pipe, naturally.
Jens Axboe912d35f2006-04-26 10:59:21 +02001591 */
Jens Axboe6a14b902007-06-14 13:08:55 +02001592static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
1593 unsigned long nr_segs, unsigned int flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001594{
Jens Axboeddac0d32006-11-04 12:49:32 +01001595 struct pipe_inode_info *pipe;
Jens Axboe912d35f2006-04-26 10:59:21 +02001596 struct page *pages[PIPE_BUFFERS];
1597 struct partial_page partial[PIPE_BUFFERS];
1598 struct splice_pipe_desc spd = {
1599 .pages = pages,
1600 .partial = partial,
1601 .flags = flags,
1602 .ops = &user_page_pipe_buf_ops,
Jens Axboebbdfc2f2007-11-06 23:29:47 -08001603 .spd_release = spd_release_page,
Jens Axboe912d35f2006-04-26 10:59:21 +02001604 };
1605
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001606 pipe = pipe_info(file->f_path.dentry->d_inode);
Jens Axboeddac0d32006-11-04 12:49:32 +01001607 if (!pipe)
Jens Axboe912d35f2006-04-26 10:59:21 +02001608 return -EBADF;
Jens Axboe912d35f2006-04-26 10:59:21 +02001609
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001610 spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
1611 flags & SPLICE_F_GIFT);
Jens Axboe912d35f2006-04-26 10:59:21 +02001612 if (spd.nr_pages <= 0)
1613 return spd.nr_pages;
1614
Jens Axboe00522fb2006-04-26 14:39:29 +02001615 return splice_to_pipe(pipe, &spd);
Jens Axboe912d35f2006-04-26 10:59:21 +02001616}
1617
Jens Axboe6a14b902007-06-14 13:08:55 +02001618/*
1619 * Note that vmsplice only really supports true splicing _from_ user memory
1620 * to a pipe, not the other way around. Splicing from user memory is a simple
1621 * operation that can be supported without any funky alignment restrictions
1622 * or nasty vm tricks. We simply map in the user memory and fill them into
1623 * a pipe. The reverse isn't quite as easy, though. There are two possible
1624 * solutions for that:
1625 *
1626 * - memcpy() the data internally, at which point we might as well just
1627 * do a regular read() on the buffer anyway.
1628 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1629 * has restriction limitations on both ends of the pipe).
1630 *
1631 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1632 *
1633 */
Heiko Carstens836f92a2009-01-14 14:14:33 +01001634SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
1635 unsigned long, nr_segs, unsigned int, flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001636{
1637 struct file *file;
1638 long error;
1639 int fput;
1640
Jens Axboe6a14b902007-06-14 13:08:55 +02001641 if (unlikely(nr_segs > UIO_MAXIOV))
1642 return -EINVAL;
1643 else if (unlikely(!nr_segs))
1644 return 0;
1645
Jens Axboe912d35f2006-04-26 10:59:21 +02001646 error = -EBADF;
1647 file = fget_light(fd, &fput);
1648 if (file) {
1649 if (file->f_mode & FMODE_WRITE)
Jens Axboe6a14b902007-06-14 13:08:55 +02001650 error = vmsplice_to_pipe(file, iov, nr_segs, flags);
1651 else if (file->f_mode & FMODE_READ)
1652 error = vmsplice_to_user(file, iov, nr_segs, flags);
Jens Axboe912d35f2006-04-26 10:59:21 +02001653
1654 fput_light(file, fput);
1655 }
1656
1657 return error;
1658}
1659
Heiko Carstens836f92a2009-01-14 14:14:33 +01001660SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1661 int, fd_out, loff_t __user *, off_out,
1662 size_t, len, unsigned int, flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001663{
1664 long error;
1665 struct file *in, *out;
1666 int fput_in, fput_out;
1667
1668 if (unlikely(!len))
1669 return 0;
1670
1671 error = -EBADF;
Ingo Molnar529565d2006-04-10 15:18:58 +02001672 in = fget_light(fd_in, &fput_in);
Jens Axboe5274f052006-03-30 15:15:30 +02001673 if (in) {
1674 if (in->f_mode & FMODE_READ) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001675 out = fget_light(fd_out, &fput_out);
Jens Axboe5274f052006-03-30 15:15:30 +02001676 if (out) {
1677 if (out->f_mode & FMODE_WRITE)
Ingo Molnar529565d2006-04-10 15:18:58 +02001678 error = do_splice(in, off_in,
1679 out, off_out,
1680 len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001681 fput_light(out, fput_out);
1682 }
1683 }
1684
1685 fput_light(in, fput_in);
1686 }
1687
1688 return error;
1689}
Jens Axboe70524492006-04-11 15:51:17 +02001690
1691/*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001692 * Make sure there's data to read. Wait for input if we can, otherwise
1693 * return an appropriate error.
1694 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001695static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001696{
1697 int ret;
1698
1699 /*
1700 * Check ->nrbufs without the inode lock first. This function
1701 * is speculative anyways, so missing one is ok.
1702 */
1703 if (pipe->nrbufs)
1704 return 0;
1705
1706 ret = 0;
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001707 pipe_lock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001708
1709 while (!pipe->nrbufs) {
1710 if (signal_pending(current)) {
1711 ret = -ERESTARTSYS;
1712 break;
1713 }
1714 if (!pipe->writers)
1715 break;
1716 if (!pipe->waiting_writers) {
1717 if (flags & SPLICE_F_NONBLOCK) {
1718 ret = -EAGAIN;
1719 break;
1720 }
1721 }
1722 pipe_wait(pipe);
1723 }
1724
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001725 pipe_unlock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001726 return ret;
1727}
1728
1729/*
1730 * Make sure there's writeable room. Wait for room if we can, otherwise
1731 * return an appropriate error.
1732 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001733static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001734{
1735 int ret;
1736
1737 /*
1738 * Check ->nrbufs without the inode lock first. This function
1739 * is speculative anyways, so missing one is ok.
1740 */
1741 if (pipe->nrbufs < PIPE_BUFFERS)
1742 return 0;
1743
1744 ret = 0;
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001745 pipe_lock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001746
1747 while (pipe->nrbufs >= PIPE_BUFFERS) {
1748 if (!pipe->readers) {
1749 send_sig(SIGPIPE, current, 0);
1750 ret = -EPIPE;
1751 break;
1752 }
1753 if (flags & SPLICE_F_NONBLOCK) {
1754 ret = -EAGAIN;
1755 break;
1756 }
1757 if (signal_pending(current)) {
1758 ret = -ERESTARTSYS;
1759 break;
1760 }
1761 pipe->waiting_writers++;
1762 pipe_wait(pipe);
1763 pipe->waiting_writers--;
1764 }
1765
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001766 pipe_unlock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001767 return ret;
1768}
1769
1770/*
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001771 * Splice contents of ipipe to opipe.
1772 */
1773static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1774 struct pipe_inode_info *opipe,
1775 size_t len, unsigned int flags)
1776{
1777 struct pipe_buffer *ibuf, *obuf;
1778 int ret = 0, nbuf;
1779 bool input_wakeup = false;
1780
1781
1782retry:
1783 ret = ipipe_prep(ipipe, flags);
1784 if (ret)
1785 return ret;
1786
1787 ret = opipe_prep(opipe, flags);
1788 if (ret)
1789 return ret;
1790
1791 /*
1792 * Potential ABBA deadlock, work around it by ordering lock
1793 * grabbing by pipe info address. Otherwise two different processes
1794 * could deadlock (one doing tee from A -> B, the other from B -> A).
1795 */
1796 pipe_double_lock(ipipe, opipe);
1797
1798 do {
1799 if (!opipe->readers) {
1800 send_sig(SIGPIPE, current, 0);
1801 if (!ret)
1802 ret = -EPIPE;
1803 break;
1804 }
1805
1806 if (!ipipe->nrbufs && !ipipe->writers)
1807 break;
1808
1809 /*
1810 * Cannot make any progress, because either the input
1811 * pipe is empty or the output pipe is full.
1812 */
1813 if (!ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) {
1814 /* Already processed some buffers, break */
1815 if (ret)
1816 break;
1817
1818 if (flags & SPLICE_F_NONBLOCK) {
1819 ret = -EAGAIN;
1820 break;
1821 }
1822
1823 /*
1824 * We raced with another reader/writer and haven't
1825 * managed to process any buffers. A zero return
1826 * value means EOF, so retry instead.
1827 */
1828 pipe_unlock(ipipe);
1829 pipe_unlock(opipe);
1830 goto retry;
1831 }
1832
1833 ibuf = ipipe->bufs + ipipe->curbuf;
1834 nbuf = (opipe->curbuf + opipe->nrbufs) % PIPE_BUFFERS;
1835 obuf = opipe->bufs + nbuf;
1836
1837 if (len >= ibuf->len) {
1838 /*
1839 * Simply move the whole buffer from ipipe to opipe
1840 */
1841 *obuf = *ibuf;
1842 ibuf->ops = NULL;
1843 opipe->nrbufs++;
1844 ipipe->curbuf = (ipipe->curbuf + 1) % PIPE_BUFFERS;
1845 ipipe->nrbufs--;
1846 input_wakeup = true;
1847 } else {
1848 /*
1849 * Get a reference to this pipe buffer,
1850 * so we can copy the contents over.
1851 */
1852 ibuf->ops->get(ipipe, ibuf);
1853 *obuf = *ibuf;
1854
1855 /*
1856 * Don't inherit the gift flag, we need to
1857 * prevent multiple steals of this page.
1858 */
1859 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1860
1861 obuf->len = len;
1862 opipe->nrbufs++;
1863 ibuf->offset += obuf->len;
1864 ibuf->len -= obuf->len;
1865 }
1866 ret += obuf->len;
1867 len -= obuf->len;
1868 } while (len);
1869
1870 pipe_unlock(ipipe);
1871 pipe_unlock(opipe);
1872
1873 /*
1874 * If we put data in the output pipe, wakeup any potential readers.
1875 */
1876 if (ret > 0) {
1877 smp_mb();
1878 if (waitqueue_active(&opipe->wait))
1879 wake_up_interruptible(&opipe->wait);
1880 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1881 }
1882 if (input_wakeup)
1883 wakeup_pipe_writers(ipipe);
1884
1885 return ret;
1886}
1887
1888/*
Jens Axboe70524492006-04-11 15:51:17 +02001889 * Link contents of ipipe to opipe.
1890 */
1891static int link_pipe(struct pipe_inode_info *ipipe,
1892 struct pipe_inode_info *opipe,
1893 size_t len, unsigned int flags)
1894{
1895 struct pipe_buffer *ibuf, *obuf;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001896 int ret = 0, i = 0, nbuf;
Jens Axboe70524492006-04-11 15:51:17 +02001897
1898 /*
1899 * Potential ABBA deadlock, work around it by ordering lock
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001900 * grabbing by pipe info address. Otherwise two different processes
Jens Axboe70524492006-04-11 15:51:17 +02001901 * could deadlock (one doing tee from A -> B, the other from B -> A).
1902 */
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001903 pipe_double_lock(ipipe, opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001904
Jens Axboeaadd06e2006-07-10 11:00:01 +02001905 do {
Jens Axboe70524492006-04-11 15:51:17 +02001906 if (!opipe->readers) {
1907 send_sig(SIGPIPE, current, 0);
1908 if (!ret)
1909 ret = -EPIPE;
1910 break;
1911 }
Jens Axboe70524492006-04-11 15:51:17 +02001912
1913 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001914 * If we have iterated all input buffers or ran out of
1915 * output room, break.
Jens Axboe70524492006-04-11 15:51:17 +02001916 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001917 if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS)
Jens Axboe70524492006-04-11 15:51:17 +02001918 break;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001919
1920 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
1921 nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
1922
Jens Axboe2a272502006-04-19 15:56:40 +02001923 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001924 * Get a reference to this pipe buffer,
1925 * so we can copy the contents over.
Jens Axboe2a272502006-04-19 15:56:40 +02001926 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001927 ibuf->ops->get(ipipe, ibuf);
Jens Axboe70524492006-04-11 15:51:17 +02001928
Jens Axboeaadd06e2006-07-10 11:00:01 +02001929 obuf = opipe->bufs + nbuf;
1930 *obuf = *ibuf;
Jens Axboe70524492006-04-11 15:51:17 +02001931
Jens Axboeaadd06e2006-07-10 11:00:01 +02001932 /*
1933 * Don't inherit the gift flag, we need to
1934 * prevent multiple steals of this page.
1935 */
1936 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1937
1938 if (obuf->len > len)
1939 obuf->len = len;
1940
1941 opipe->nrbufs++;
1942 ret += obuf->len;
1943 len -= obuf->len;
1944 i++;
1945 } while (len);
Jens Axboe70524492006-04-11 15:51:17 +02001946
Jens Axboe02cf01a2008-02-20 10:34:51 +01001947 /*
1948 * return EAGAIN if we have the potential of some data in the
1949 * future, otherwise just return 0
1950 */
1951 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1952 ret = -EAGAIN;
1953
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001954 pipe_unlock(ipipe);
1955 pipe_unlock(opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001956
Jens Axboeaadd06e2006-07-10 11:00:01 +02001957 /*
1958 * If we put data in the output pipe, wakeup any potential readers.
1959 */
1960 if (ret > 0) {
Jens Axboe70524492006-04-11 15:51:17 +02001961 smp_mb();
1962 if (waitqueue_active(&opipe->wait))
1963 wake_up_interruptible(&opipe->wait);
1964 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1965 }
1966
1967 return ret;
1968}
1969
1970/*
1971 * This is a tee(1) implementation that works on pipes. It doesn't copy
1972 * any data, it simply references the 'in' pages on the 'out' pipe.
1973 * The 'flags' used are the SPLICE_F_* variants, currently the only
1974 * applicable one is SPLICE_F_NONBLOCK.
1975 */
1976static long do_tee(struct file *in, struct file *out, size_t len,
1977 unsigned int flags)
1978{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001979 struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode);
1980 struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001981 int ret = -EINVAL;
Jens Axboe70524492006-04-11 15:51:17 +02001982
1983 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001984 * Duplicate the contents of ipipe to opipe without actually
1985 * copying the data.
Jens Axboe70524492006-04-11 15:51:17 +02001986 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001987 if (ipipe && opipe && ipipe != opipe) {
1988 /*
1989 * Keep going, unless we encounter an error. The ipipe/opipe
1990 * ordering doesn't really matter.
1991 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001992 ret = ipipe_prep(ipipe, flags);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001993 if (!ret) {
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001994 ret = opipe_prep(opipe, flags);
Jens Axboe02cf01a2008-02-20 10:34:51 +01001995 if (!ret)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001996 ret = link_pipe(ipipe, opipe, len, flags);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001997 }
1998 }
Jens Axboe70524492006-04-11 15:51:17 +02001999
Jens Axboeaadd06e2006-07-10 11:00:01 +02002000 return ret;
Jens Axboe70524492006-04-11 15:51:17 +02002001}
2002
Heiko Carstens836f92a2009-01-14 14:14:33 +01002003SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
Jens Axboe70524492006-04-11 15:51:17 +02002004{
2005 struct file *in;
2006 int error, fput_in;
2007
2008 if (unlikely(!len))
2009 return 0;
2010
2011 error = -EBADF;
2012 in = fget_light(fdin, &fput_in);
2013 if (in) {
2014 if (in->f_mode & FMODE_READ) {
2015 int fput_out;
2016 struct file *out = fget_light(fdout, &fput_out);
2017
2018 if (out) {
2019 if (out->f_mode & FMODE_WRITE)
2020 error = do_tee(in, out, len, flags);
2021 fput_light(out, fput_out);
2022 }
2023 }
2024 fput_light(in, fput_in);
2025 }
2026
2027 return error;
2028}