blob: aa5f6f60b3055f8a35b59084f0c652cb0e5c2125 [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>
Jens Axboe5274f052006-03-30 15:15:30 +020024#include <linux/mm_inline.h>
Jens Axboe5abc97a2006-03-30 15:16:46 +020025#include <linux/swap.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020026#include <linux/writeback.h>
27#include <linux/buffer_head.h>
Jeff Garzika0f06782006-03-30 23:06:13 -050028#include <linux/module.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020029#include <linux/syscalls.h>
Jens Axboe912d35f2006-04-26 10:59:21 +020030#include <linux/uio.h>
James Morris29ce2052007-07-13 11:44:32 +020031#include <linux/security.h>
Jens Axboe5274f052006-03-30 15:15:30 +020032
Jens Axboe83f91352006-04-02 23:05:09 +020033/*
34 * Attempt to steal a page from a pipe buffer. This should perhaps go into
35 * a vm helper function, it's already simplified quite a bit by the
36 * addition of remove_mapping(). If success is returned, the caller may
37 * attempt to reuse this page for another destination.
38 */
Jens Axboe76ad4d12006-05-03 10:41:33 +020039static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
Jens Axboe5abc97a2006-03-30 15:16:46 +020040 struct pipe_buffer *buf)
41{
42 struct page *page = buf->page;
Jens Axboe9e94cd42006-06-20 15:01:12 +020043 struct address_space *mapping;
Jens Axboe5abc97a2006-03-30 15:16:46 +020044
Jens Axboe9e0267c2006-04-19 15:57:31 +020045 lock_page(page);
46
Jens Axboe9e94cd42006-06-20 15:01:12 +020047 mapping = page_mapping(page);
48 if (mapping) {
49 WARN_ON(!PageUptodate(page));
Jens Axboe5abc97a2006-03-30 15:16:46 +020050
Jens Axboe9e94cd42006-06-20 15:01:12 +020051 /*
52 * At least for ext2 with nobh option, we need to wait on
53 * writeback completing on this page, since we'll remove it
54 * from the pagecache. Otherwise truncate wont wait on the
55 * page, allowing the disk blocks to be reused by someone else
56 * before we actually wrote our data to them. fs corruption
57 * ensues.
58 */
59 wait_on_page_writeback(page);
Jens Axboead8d6f02006-04-02 23:10:32 +020060
Jens Axboeca39d652008-05-20 21:27:41 +020061 if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
62 goto out_unlock;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020063
Jens Axboe9e94cd42006-06-20 15:01:12 +020064 /*
65 * If we succeeded in removing the mapping, set LRU flag
66 * and return good.
67 */
68 if (remove_mapping(mapping, page)) {
69 buf->flags |= PIPE_BUF_FLAG_LRU;
70 return 0;
71 }
Jens Axboe9e0267c2006-04-19 15:57:31 +020072 }
Jens Axboe5abc97a2006-03-30 15:16:46 +020073
Jens Axboe9e94cd42006-06-20 15:01:12 +020074 /*
75 * Raced with truncate or failed to remove page from current
76 * address space, unlock and return failure.
77 */
Jens Axboeca39d652008-05-20 21:27:41 +020078out_unlock:
Jens Axboe9e94cd42006-06-20 15:01:12 +020079 unlock_page(page);
80 return 1;
Jens Axboe5abc97a2006-03-30 15:16:46 +020081}
82
Jens Axboe76ad4d12006-05-03 10:41:33 +020083static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +020084 struct pipe_buffer *buf)
85{
86 page_cache_release(buf->page);
Jens Axboe14328732006-05-03 10:35:26 +020087 buf->flags &= ~PIPE_BUF_FLAG_LRU;
Jens Axboe5274f052006-03-30 15:15:30 +020088}
89
Jens Axboe08457182007-06-12 20:51:32 +020090/*
91 * Check whether the contents of buf is OK to access. Since the content
92 * is a page cache page, IO may be in flight.
93 */
Jens Axboecac36bb02007-06-14 13:10:48 +020094static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
95 struct pipe_buffer *buf)
Jens Axboe5274f052006-03-30 15:15:30 +020096{
97 struct page *page = buf->page;
Jens Axboe49d0b212006-04-10 09:04:41 +020098 int err;
Jens Axboe5274f052006-03-30 15:15:30 +020099
100 if (!PageUptodate(page)) {
Jens Axboe49d0b212006-04-10 09:04:41 +0200101 lock_page(page);
102
103 /*
104 * Page got truncated/unhashed. This will cause a 0-byte
Ingo Molnar73d62d82006-04-11 13:57:21 +0200105 * splice, if this is the first page.
Jens Axboe49d0b212006-04-10 09:04:41 +0200106 */
107 if (!page->mapping) {
108 err = -ENODATA;
109 goto error;
110 }
111
112 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +0200113 * Uh oh, read-error from disk.
Jens Axboe49d0b212006-04-10 09:04:41 +0200114 */
115 if (!PageUptodate(page)) {
116 err = -EIO;
117 goto error;
118 }
119
120 /*
Jens Axboef84d7512006-05-01 19:59:03 +0200121 * Page is ok afterall, we are done.
Jens Axboe49d0b212006-04-10 09:04:41 +0200122 */
Jens Axboe5274f052006-03-30 15:15:30 +0200123 unlock_page(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200124 }
125
Jens Axboef84d7512006-05-01 19:59:03 +0200126 return 0;
Jens Axboe49d0b212006-04-10 09:04:41 +0200127error:
128 unlock_page(page);
Jens Axboef84d7512006-05-01 19:59:03 +0200129 return err;
Jens Axboe70524492006-04-11 15:51:17 +0200130}
131
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800132static const struct pipe_buf_operations page_cache_pipe_buf_ops = {
Jens Axboe5274f052006-03-30 15:15:30 +0200133 .can_merge = 0,
Jens Axboef84d7512006-05-01 19:59:03 +0200134 .map = generic_pipe_buf_map,
135 .unmap = generic_pipe_buf_unmap,
Jens Axboecac36bb02007-06-14 13:10:48 +0200136 .confirm = page_cache_pipe_buf_confirm,
Jens Axboe5274f052006-03-30 15:15:30 +0200137 .release = page_cache_pipe_buf_release,
Jens Axboe5abc97a2006-03-30 15:16:46 +0200138 .steal = page_cache_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200139 .get = generic_pipe_buf_get,
Jens Axboe5274f052006-03-30 15:15:30 +0200140};
141
Jens Axboe912d35f2006-04-26 10:59:21 +0200142static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
143 struct pipe_buffer *buf)
144{
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200145 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
146 return 1;
147
Jens Axboe14328732006-05-03 10:35:26 +0200148 buf->flags |= PIPE_BUF_FLAG_LRU;
Jens Axboe330ab712006-05-02 15:29:57 +0200149 return generic_pipe_buf_steal(pipe, buf);
Jens Axboe912d35f2006-04-26 10:59:21 +0200150}
151
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800152static const struct pipe_buf_operations user_page_pipe_buf_ops = {
Jens Axboe912d35f2006-04-26 10:59:21 +0200153 .can_merge = 0,
Jens Axboef84d7512006-05-01 19:59:03 +0200154 .map = generic_pipe_buf_map,
155 .unmap = generic_pipe_buf_unmap,
Jens Axboecac36bb02007-06-14 13:10:48 +0200156 .confirm = generic_pipe_buf_confirm,
Jens Axboe912d35f2006-04-26 10:59:21 +0200157 .release = page_cache_pipe_buf_release,
158 .steal = user_page_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200159 .get = generic_pipe_buf_get,
Jens Axboe912d35f2006-04-26 10:59:21 +0200160};
161
Jens Axboe932cc6d2007-06-21 13:10:21 +0200162/**
163 * splice_to_pipe - fill passed data into a pipe
164 * @pipe: pipe to fill
165 * @spd: data to fill
166 *
167 * Description:
Randy Dunlap79685b82007-07-27 08:08:51 +0200168 * @spd contains a map of pages and len/offset tuples, along with
Jens Axboe932cc6d2007-06-21 13:10:21 +0200169 * the struct pipe_buf_operations associated with these pages. This
170 * function will link that data to the pipe.
171 *
Jens Axboe83f91352006-04-02 23:05:09 +0200172 */
Jens Axboed6b29d72007-06-04 09:59:47 +0200173ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
174 struct splice_pipe_desc *spd)
Jens Axboe5274f052006-03-30 15:15:30 +0200175{
Jens Axboe00de00b2007-06-15 13:14:22 +0200176 unsigned int spd_pages = spd->nr_pages;
Jens Axboe912d35f2006-04-26 10:59:21 +0200177 int ret, do_wakeup, page_nr;
Jens Axboe5274f052006-03-30 15:15:30 +0200178
179 ret = 0;
180 do_wakeup = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +0200181 page_nr = 0;
Jens Axboe5274f052006-03-30 15:15:30 +0200182
Ingo Molnar3a326a22006-04-10 15:18:35 +0200183 if (pipe->inode)
184 mutex_lock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200185
Jens Axboe5274f052006-03-30 15:15:30 +0200186 for (;;) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200187 if (!pipe->readers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200188 send_sig(SIGPIPE, current, 0);
189 if (!ret)
190 ret = -EPIPE;
191 break;
192 }
193
Jens Axboe6f767b02006-04-11 13:53:56 +0200194 if (pipe->nrbufs < PIPE_BUFFERS) {
195 int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
Ingo Molnar3a326a22006-04-10 15:18:35 +0200196 struct pipe_buffer *buf = pipe->bufs + newbuf;
Jens Axboe5274f052006-03-30 15:15:30 +0200197
Jens Axboe912d35f2006-04-26 10:59:21 +0200198 buf->page = spd->pages[page_nr];
199 buf->offset = spd->partial[page_nr].offset;
200 buf->len = spd->partial[page_nr].len;
Jens Axboe497f9622007-06-11 12:00:45 +0200201 buf->private = spd->partial[page_nr].private;
Jens Axboe912d35f2006-04-26 10:59:21 +0200202 buf->ops = spd->ops;
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200203 if (spd->flags & SPLICE_F_GIFT)
204 buf->flags |= PIPE_BUF_FLAG_GIFT;
205
Jens Axboe6f767b02006-04-11 13:53:56 +0200206 pipe->nrbufs++;
Jens Axboe912d35f2006-04-26 10:59:21 +0200207 page_nr++;
208 ret += buf->len;
209
Jens Axboe6f767b02006-04-11 13:53:56 +0200210 if (pipe->inode)
211 do_wakeup = 1;
Jens Axboe5274f052006-03-30 15:15:30 +0200212
Jens Axboe912d35f2006-04-26 10:59:21 +0200213 if (!--spd->nr_pages)
Jens Axboe5274f052006-03-30 15:15:30 +0200214 break;
Jens Axboe6f767b02006-04-11 13:53:56 +0200215 if (pipe->nrbufs < PIPE_BUFFERS)
Jens Axboe5274f052006-03-30 15:15:30 +0200216 continue;
217
218 break;
219 }
220
Jens Axboe912d35f2006-04-26 10:59:21 +0200221 if (spd->flags & SPLICE_F_NONBLOCK) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700222 if (!ret)
223 ret = -EAGAIN;
224 break;
225 }
226
Jens Axboe5274f052006-03-30 15:15:30 +0200227 if (signal_pending(current)) {
228 if (!ret)
229 ret = -ERESTARTSYS;
230 break;
231 }
232
233 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200234 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200235 if (waitqueue_active(&pipe->wait))
236 wake_up_interruptible_sync(&pipe->wait);
237 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
Jens Axboe5274f052006-03-30 15:15:30 +0200238 do_wakeup = 0;
239 }
240
Ingo Molnar3a326a22006-04-10 15:18:35 +0200241 pipe->waiting_writers++;
242 pipe_wait(pipe);
243 pipe->waiting_writers--;
Jens Axboe5274f052006-03-30 15:15:30 +0200244 }
245
Jens Axboe02676e52007-06-15 13:16:13 +0200246 if (pipe->inode) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200247 mutex_unlock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200248
Jens Axboe02676e52007-06-15 13:16:13 +0200249 if (do_wakeup) {
250 smp_mb();
251 if (waitqueue_active(&pipe->wait))
252 wake_up_interruptible(&pipe->wait);
253 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
254 }
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 Wu431a48202007-07-19 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 Wu431a48202007-07-19 01:48:05 -0700302 * readahead/allocate the rest and fill in the holes.
Jens Axboeeb207962006-04-27 11:05:22 +0200303 */
Fengguang Wu431a48202007-07-19 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 Wu431a48202007-07-19 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) {
Jens Axboe8191ecd2008-04-10 08:24:25 +0200374 if (TestSetPageLocked(page)) {
375 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 /*
382 * page was truncated, stop here. if this isn't the
383 * first page, we'll just complete what we already
384 * added
385 */
386 if (!page->mapping) {
387 unlock_page(page);
Jens Axboe7480a902006-04-11 13:52:47 +0200388 break;
389 }
390 /*
391 * page was already under io and is now done, great
392 */
393 if (PageUptodate(page)) {
394 unlock_page(page);
395 goto fill_it;
396 }
397
Jens Axboe7480a902006-04-11 13:52:47 +0200398 /*
399 * need to read in the page
400 */
401 error = mapping->a_ops->readpage(in, page);
Jens Axboe7480a902006-04-11 13:52:47 +0200402 if (unlikely(error)) {
Jens Axboeeb207962006-04-27 11:05:22 +0200403 /*
404 * We really should re-lookup the page here,
405 * but it complicates things a lot. Instead
406 * lets just do what we already stored, and
407 * we'll get it the next time we are called.
408 */
Jens Axboe7480a902006-04-11 13:52:47 +0200409 if (error == AOP_TRUNCATED_PAGE)
Jens Axboeeb207962006-04-27 11:05:22 +0200410 error = 0;
411
Jens Axboe7480a902006-04-11 13:52:47 +0200412 break;
413 }
Jens Axboe620a3242007-06-07 09:39:42 +0200414 }
415fill_it:
416 /*
417 * i_size must be checked after PageUptodate.
418 */
419 isize = i_size_read(mapping->host);
420 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
421 if (unlikely(!isize || index > end_index))
422 break;
423
424 /*
425 * if this is the last page, see if we need to shrink
426 * the length and stop
427 */
428 if (end_index == index) {
429 unsigned int plen;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200430
431 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200432 * max good bytes in this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200433 */
Jens Axboe620a3242007-06-07 09:39:42 +0200434 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
435 if (plen <= loff)
Jens Axboe91ad66e2006-04-19 15:55:10 +0200436 break;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200437
438 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200439 * force quit after adding this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200440 */
Jens Axboe620a3242007-06-07 09:39:42 +0200441 this_len = min(this_len, plen - loff);
442 len = this_len;
Jens Axboe7480a902006-04-11 13:52:47 +0200443 }
Jens Axboe620a3242007-06-07 09:39:42 +0200444
Jens Axboeeb207962006-04-27 11:05:22 +0200445 partial[page_nr].offset = loff;
446 partial[page_nr].len = this_len;
Jens Axboe82aa5d62006-04-20 13:05:48 +0200447 len -= this_len;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200448 loff = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200449 spd.nr_pages++;
450 index++;
Jens Axboe5274f052006-03-30 15:15:30 +0200451 }
452
Jens Axboeeb207962006-04-27 11:05:22 +0200453 /*
Hugh Dickins475ecad2007-06-07 09:36:00 +0200454 * Release any pages at the end, if we quit early. 'page_nr' is how far
Jens Axboeeb207962006-04-27 11:05:22 +0200455 * we got, 'nr_pages' is how many pages are in the map.
456 */
457 while (page_nr < nr_pages)
458 page_cache_release(pages[page_nr++]);
Fengguang Wuf4e6b492007-10-16 01:24:33 -0700459 in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
Jens Axboeeb207962006-04-27 11:05:22 +0200460
Jens Axboe912d35f2006-04-26 10:59:21 +0200461 if (spd.nr_pages)
Jens Axboe00522fb2006-04-26 14:39:29 +0200462 return splice_to_pipe(pipe, &spd);
Jens Axboe5274f052006-03-30 15:15:30 +0200463
Jens Axboe7480a902006-04-11 13:52:47 +0200464 return error;
Jens Axboe5274f052006-03-30 15:15:30 +0200465}
466
Jens Axboe83f91352006-04-02 23:05:09 +0200467/**
468 * generic_file_splice_read - splice data from file to a pipe
469 * @in: file to splice from
Jens Axboe932cc6d2007-06-21 13:10:21 +0200470 * @ppos: position in @in
Jens Axboe83f91352006-04-02 23:05:09 +0200471 * @pipe: pipe to splice to
472 * @len: number of bytes to splice
473 * @flags: splice modifier flags
474 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200475 * Description:
476 * Will read pages from given file and fill them into a pipe. Can be
477 * used as long as the address_space operations for the source implements
478 * a readpage() hook.
479 *
Jens Axboe83f91352006-04-02 23:05:09 +0200480 */
Jens Axboecbb7e572006-04-11 14:57:50 +0200481ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
482 struct pipe_inode_info *pipe, size_t len,
483 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200484{
Jens Axboed366d3982007-06-01 14:54:11 +0200485 loff_t isize, left;
Jens Axboe8191ecd2008-04-10 08:24:25 +0200486 int ret;
Jens Axboed366d3982007-06-01 14:54:11 +0200487
488 isize = i_size_read(in->f_mapping->host);
489 if (unlikely(*ppos >= isize))
490 return 0;
491
492 left = isize - *ppos;
493 if (unlikely(left < len))
494 len = left;
Jens Axboe5274f052006-03-30 15:15:30 +0200495
Jens Axboe8191ecd2008-04-10 08:24:25 +0200496 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
497 if (ret > 0)
Jens Axboecbb7e572006-04-11 14:57:50 +0200498 *ppos += ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200499
500 return ret;
501}
502
Jens Axboe059a8f32006-04-02 23:06:05 +0200503EXPORT_SYMBOL(generic_file_splice_read);
504
Jens Axboe5274f052006-03-30 15:15:30 +0200505/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200506 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
Jens Axboe016b6612006-04-25 15:42:00 +0200507 * using sendpage(). Return the number of bytes sent.
Jens Axboe5274f052006-03-30 15:15:30 +0200508 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200509static int pipe_to_sendpage(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +0200510 struct pipe_buffer *buf, struct splice_desc *sd)
511{
Jens Axboe6a14b902007-06-14 13:08:55 +0200512 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200513 loff_t pos = sd->pos;
Jens Axboef84d7512006-05-01 19:59:03 +0200514 int ret, more;
Jens Axboe5274f052006-03-30 15:15:30 +0200515
Jens Axboecac36bb02007-06-14 13:10:48 +0200516 ret = buf->ops->confirm(pipe, buf);
Jens Axboef84d7512006-05-01 19:59:03 +0200517 if (!ret) {
518 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200519
Jens Axboef84d7512006-05-01 19:59:03 +0200520 ret = file->f_op->sendpage(file, buf->page, buf->offset,
521 sd->len, &pos, more);
522 }
Jens Axboe5274f052006-03-30 15:15:30 +0200523
Jens Axboe016b6612006-04-25 15:42:00 +0200524 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200525}
526
527/*
528 * This is a little more tricky than the file -> pipe splicing. There are
529 * basically three cases:
530 *
531 * - Destination page already exists in the address space and there
532 * are users of it. For that case we have no other option that
533 * copying the data. Tough luck.
534 * - Destination page already exists in the address space, but there
535 * are no users of it. Make sure it's uptodate, then drop it. Fall
536 * through to last case.
537 * - Destination page does not exist, we can add the pipe page to
538 * the page cache and avoid the copy.
539 *
Jens Axboe83f91352006-04-02 23:05:09 +0200540 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
541 * sd->flags), we attempt to migrate pages from the pipe to the output
542 * file address space page cache. This is possible if no one else has
543 * the pipe page referenced outside of the pipe and page cache. If
544 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
545 * a new page in the output file page cache and fill/dirty that.
Jens Axboe5274f052006-03-30 15:15:30 +0200546 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200547static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
Jens Axboe5274f052006-03-30 15:15:30 +0200548 struct splice_desc *sd)
549{
Jens Axboe6a14b902007-06-14 13:08:55 +0200550 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200551 struct address_space *mapping = file->f_mapping;
Jens Axboe016b6612006-04-25 15:42:00 +0200552 unsigned int offset, this_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200553 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -0700554 void *fsdata;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200555 int ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200556
557 /*
Jens Axboe49d0b212006-04-10 09:04:41 +0200558 * make sure the data in this buffer is uptodate
Jens Axboe5274f052006-03-30 15:15:30 +0200559 */
Jens Axboecac36bb02007-06-14 13:10:48 +0200560 ret = buf->ops->confirm(pipe, buf);
Jens Axboef84d7512006-05-01 19:59:03 +0200561 if (unlikely(ret))
562 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200563
Jens Axboe5274f052006-03-30 15:15:30 +0200564 offset = sd->pos & ~PAGE_CACHE_MASK;
565
Jens Axboe016b6612006-04-25 15:42:00 +0200566 this_len = sd->len;
567 if (this_len + offset > PAGE_CACHE_SIZE)
568 this_len = PAGE_CACHE_SIZE - offset;
569
Nick Pigginafddba42007-10-16 01:25:01 -0700570 ret = pagecache_write_begin(file, mapping, sd->pos, this_len,
571 AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
572 if (unlikely(ret))
573 goto out;
Jens Axboe5274f052006-03-30 15:15:30 +0200574
Jens Axboe0568b402006-05-01 19:50:48 +0200575 if (buf->page != page) {
Jens Axboef84d7512006-05-01 19:59:03 +0200576 /*
577 * Careful, ->map() uses KM_USER0!
578 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200579 char *src = buf->ops->map(pipe, buf, 1);
Jens Axboef84d7512006-05-01 19:59:03 +0200580 char *dst = kmap_atomic(page, KM_USER1);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200581
Jens Axboe016b6612006-04-25 15:42:00 +0200582 memcpy(dst + offset, src + buf->offset, this_len);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200583 flush_dcache_page(page);
Jens Axboef84d7512006-05-01 19:59:03 +0200584 kunmap_atomic(dst, KM_USER1);
Jens Axboe76ad4d12006-05-03 10:41:33 +0200585 buf->ops->unmap(pipe, buf, src);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200586 }
Nick Pigginafddba42007-10-16 01:25:01 -0700587 ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len,
588 page, fsdata);
Jens Axboe5274f052006-03-30 15:15:30 +0200589out:
Jens Axboe5274f052006-03-30 15:15:30 +0200590 return ret;
591}
592
Jens Axboe932cc6d2007-06-21 13:10:21 +0200593/**
594 * __splice_from_pipe - splice data from a pipe to given actor
595 * @pipe: pipe to splice from
596 * @sd: information to @actor
597 * @actor: handler that splices the data
598 *
599 * Description:
600 * This function does little more than loop over the pipe and call
601 * @actor to do the actual moving of a single struct pipe_buffer to
602 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
603 * pipe_to_user.
604 *
Jens Axboe83f91352006-04-02 23:05:09 +0200605 */
Jens Axboec66ab6f2007-06-12 21:17:17 +0200606ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
607 splice_actor *actor)
Jens Axboe5274f052006-03-30 15:15:30 +0200608{
Jens Axboe5274f052006-03-30 15:15:30 +0200609 int ret, do_wakeup, err;
Jens Axboe5274f052006-03-30 15:15:30 +0200610
611 ret = 0;
612 do_wakeup = 0;
613
Jens Axboe5274f052006-03-30 15:15:30 +0200614 for (;;) {
Jens Axboe6f767b02006-04-11 13:53:56 +0200615 if (pipe->nrbufs) {
616 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800617 const struct pipe_buf_operations *ops = buf->ops;
Jens Axboe5274f052006-03-30 15:15:30 +0200618
Jens Axboec66ab6f2007-06-12 21:17:17 +0200619 sd->len = buf->len;
620 if (sd->len > sd->total_len)
621 sd->len = sd->total_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200622
Jens Axboec66ab6f2007-06-12 21:17:17 +0200623 err = actor(pipe, buf, sd);
Jens Axboe016b6612006-04-25 15:42:00 +0200624 if (err <= 0) {
Jens Axboe5274f052006-03-30 15:15:30 +0200625 if (!ret && err != -ENODATA)
626 ret = err;
627
628 break;
629 }
630
Jens Axboe016b6612006-04-25 15:42:00 +0200631 ret += err;
632 buf->offset += err;
633 buf->len -= err;
634
Jens Axboec66ab6f2007-06-12 21:17:17 +0200635 sd->len -= err;
636 sd->pos += err;
637 sd->total_len -= err;
638 if (sd->len)
Jens Axboe016b6612006-04-25 15:42:00 +0200639 continue;
Ingo Molnar73d62d82006-04-11 13:57:21 +0200640
Jens Axboe5274f052006-03-30 15:15:30 +0200641 if (!buf->len) {
642 buf->ops = NULL;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200643 ops->release(pipe, buf);
Jens Axboe6f767b02006-04-11 13:53:56 +0200644 pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
645 pipe->nrbufs--;
646 if (pipe->inode)
647 do_wakeup = 1;
Jens Axboe5274f052006-03-30 15:15:30 +0200648 }
649
Jens Axboec66ab6f2007-06-12 21:17:17 +0200650 if (!sd->total_len)
Jens Axboe5274f052006-03-30 15:15:30 +0200651 break;
652 }
653
Jens Axboe6f767b02006-04-11 13:53:56 +0200654 if (pipe->nrbufs)
Jens Axboe5274f052006-03-30 15:15:30 +0200655 continue;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200656 if (!pipe->writers)
Jens Axboe5274f052006-03-30 15:15:30 +0200657 break;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200658 if (!pipe->waiting_writers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200659 if (ret)
660 break;
661 }
662
Jens Axboec66ab6f2007-06-12 21:17:17 +0200663 if (sd->flags & SPLICE_F_NONBLOCK) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700664 if (!ret)
665 ret = -EAGAIN;
666 break;
667 }
668
Jens Axboe5274f052006-03-30 15:15:30 +0200669 if (signal_pending(current)) {
670 if (!ret)
671 ret = -ERESTARTSYS;
672 break;
673 }
674
675 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200676 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200677 if (waitqueue_active(&pipe->wait))
678 wake_up_interruptible_sync(&pipe->wait);
679 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
Jens Axboe5274f052006-03-30 15:15:30 +0200680 do_wakeup = 0;
681 }
682
Ingo Molnar3a326a22006-04-10 15:18:35 +0200683 pipe_wait(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200684 }
685
Jens Axboe5274f052006-03-30 15:15:30 +0200686 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200687 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200688 if (waitqueue_active(&pipe->wait))
689 wake_up_interruptible(&pipe->wait);
690 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
Jens Axboe5274f052006-03-30 15:15:30 +0200691 }
692
Jens Axboe5274f052006-03-30 15:15:30 +0200693 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200694}
Mark Fasheh40bee44e2007-03-21 13:11:02 +0100695EXPORT_SYMBOL(__splice_from_pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200696
Jens Axboe932cc6d2007-06-21 13:10:21 +0200697/**
698 * splice_from_pipe - splice data from a pipe to a file
699 * @pipe: pipe to splice from
700 * @out: file to splice to
701 * @ppos: position in @out
702 * @len: how many bytes to splice
703 * @flags: splice modifier flags
704 * @actor: handler that splices the data
705 *
706 * Description:
707 * See __splice_from_pipe. This function locks the input and output inodes,
708 * otherwise it's identical to __splice_from_pipe().
709 *
710 */
Mark Fasheh6da61802006-10-17 18:43:07 +0200711ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
712 loff_t *ppos, size_t len, unsigned int flags,
713 splice_actor *actor)
714{
715 ssize_t ret;
716 struct inode *inode = out->f_mapping->host;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200717 struct splice_desc sd = {
718 .total_len = len,
719 .flags = flags,
720 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +0200721 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +0200722 };
Mark Fasheh6da61802006-10-17 18:43:07 +0200723
724 /*
725 * The actor worker might be calling ->prepare_write and
726 * ->commit_write. Most of the time, these expect i_mutex to
727 * be held. Since this may result in an ABBA deadlock with
728 * pipe->inode, we have to order lock acquiry here.
729 */
730 inode_double_lock(inode, pipe->inode);
Jens Axboec66ab6f2007-06-12 21:17:17 +0200731 ret = __splice_from_pipe(pipe, &sd, actor);
Mark Fasheh6da61802006-10-17 18:43:07 +0200732 inode_double_unlock(inode, pipe->inode);
733
734 return ret;
735}
736
737/**
738 * generic_file_splice_write_nolock - generic_file_splice_write without mutexes
739 * @pipe: pipe info
740 * @out: file to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +0200741 * @ppos: position in @out
Mark Fasheh6da61802006-10-17 18:43:07 +0200742 * @len: number of bytes to splice
743 * @flags: splice modifier flags
744 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200745 * Description:
746 * Will either move or copy pages (determined by @flags options) from
747 * the given pipe inode to the given file. The caller is responsible
748 * for acquiring i_mutex on both inodes.
Mark Fasheh6da61802006-10-17 18:43:07 +0200749 *
750 */
751ssize_t
752generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
753 loff_t *ppos, size_t len, unsigned int flags)
754{
755 struct address_space *mapping = out->f_mapping;
756 struct inode *inode = mapping->host;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200757 struct splice_desc sd = {
758 .total_len = len,
759 .flags = flags,
760 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +0200761 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +0200762 };
Mark Fasheh6da61802006-10-17 18:43:07 +0200763 ssize_t ret;
764 int err;
765
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800766 err = remove_suid(out->f_path.dentry);
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200767 if (unlikely(err))
768 return err;
769
Jens Axboec66ab6f2007-06-12 21:17:17 +0200770 ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
Mark Fasheh6da61802006-10-17 18:43:07 +0200771 if (ret > 0) {
Jens Axboe17ee4f42007-06-15 13:10:37 +0200772 unsigned long nr_pages;
773
Mark Fasheh6da61802006-10-17 18:43:07 +0200774 *ppos += ret;
Jens Axboe17ee4f42007-06-15 13:10:37 +0200775 nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Mark Fasheh6da61802006-10-17 18:43:07 +0200776
777 /*
778 * If file or inode is SYNC and we actually wrote some data,
779 * sync it.
780 */
781 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
782 err = generic_osync_inode(inode, mapping,
783 OSYNC_METADATA|OSYNC_DATA);
784
785 if (err)
786 ret = err;
787 }
Jens Axboe17ee4f42007-06-15 13:10:37 +0200788 balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
Mark Fasheh6da61802006-10-17 18:43:07 +0200789 }
790
791 return ret;
792}
793
794EXPORT_SYMBOL(generic_file_splice_write_nolock);
795
Jens Axboe83f91352006-04-02 23:05:09 +0200796/**
797 * generic_file_splice_write - splice data from a pipe to a file
Ingo Molnar3a326a22006-04-10 15:18:35 +0200798 * @pipe: pipe info
Jens Axboe83f91352006-04-02 23:05:09 +0200799 * @out: file to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +0200800 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +0200801 * @len: number of bytes to splice
802 * @flags: splice modifier flags
803 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200804 * Description:
805 * Will either move or copy pages (determined by @flags options) from
806 * the given pipe inode to the given file.
Jens Axboe83f91352006-04-02 23:05:09 +0200807 *
808 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200809ssize_t
810generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +0200811 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200812{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200813 struct address_space *mapping = out->f_mapping;
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200814 struct inode *inode = mapping->host;
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +0200815 struct splice_desc sd = {
816 .total_len = len,
817 .flags = flags,
818 .pos = *ppos,
819 .u.file = out,
820 };
Ingo Molnar3a326a22006-04-10 15:18:35 +0200821 ssize_t ret;
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200822
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +0200823 inode_double_lock(inode, pipe->inode);
824 ret = remove_suid(out->f_path.dentry);
825 if (likely(!ret))
826 ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
827 inode_double_unlock(inode, pipe->inode);
Jens Axboea4514eb2006-04-19 15:57:05 +0200828 if (ret > 0) {
Jens Axboe17ee4f42007-06-15 13:10:37 +0200829 unsigned long nr_pages;
830
Jens Axboea4514eb2006-04-19 15:57:05 +0200831 *ppos += ret;
Jens Axboe17ee4f42007-06-15 13:10:37 +0200832 nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200833
Jens Axboea4514eb2006-04-19 15:57:05 +0200834 /*
835 * If file or inode is SYNC and we actually wrote some data,
836 * sync it.
837 */
838 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +0200839 int err;
840
Jens Axboea4514eb2006-04-19 15:57:05 +0200841 mutex_lock(&inode->i_mutex);
842 err = generic_osync_inode(inode, mapping,
843 OSYNC_METADATA|OSYNC_DATA);
844 mutex_unlock(&inode->i_mutex);
845
846 if (err)
847 ret = err;
848 }
Jens Axboe17ee4f42007-06-15 13:10:37 +0200849 balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200850 }
851
852 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200853}
854
Jens Axboe059a8f32006-04-02 23:06:05 +0200855EXPORT_SYMBOL(generic_file_splice_write);
856
Jens Axboe83f91352006-04-02 23:05:09 +0200857/**
858 * generic_splice_sendpage - splice data from a pipe to a socket
Jens Axboe932cc6d2007-06-21 13:10:21 +0200859 * @pipe: pipe to splice from
Jens Axboe83f91352006-04-02 23:05:09 +0200860 * @out: socket to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +0200861 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +0200862 * @len: number of bytes to splice
863 * @flags: splice modifier flags
864 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200865 * Description:
866 * Will send @len bytes from the pipe to a network socket. No data copying
867 * is involved.
Jens Axboe83f91352006-04-02 23:05:09 +0200868 *
869 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200870ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +0200871 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200872{
Jens Axboe00522fb2006-04-26 14:39:29 +0200873 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
Jens Axboe5274f052006-03-30 15:15:30 +0200874}
875
Jens Axboe059a8f32006-04-02 23:06:05 +0200876EXPORT_SYMBOL(generic_splice_sendpage);
Jeff Garzika0f06782006-03-30 23:06:13 -0500877
Jens Axboe83f91352006-04-02 23:05:09 +0200878/*
879 * Attempt to initiate a splice from pipe to file.
880 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200881static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +0200882 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200883{
Jens Axboe5274f052006-03-30 15:15:30 +0200884 int ret;
885
Jens Axboe49570e92006-04-11 13:56:09 +0200886 if (unlikely(!out->f_op || !out->f_op->splice_write))
Jens Axboe5274f052006-03-30 15:15:30 +0200887 return -EINVAL;
888
Jens Axboe49570e92006-04-11 13:56:09 +0200889 if (unlikely(!(out->f_mode & FMODE_WRITE)))
Jens Axboe5274f052006-03-30 15:15:30 +0200890 return -EBADF;
891
Jens Axboecbb7e572006-04-11 14:57:50 +0200892 ret = rw_verify_area(WRITE, out, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +0200893 if (unlikely(ret < 0))
894 return ret;
895
Jens Axboecbb7e572006-04-11 14:57:50 +0200896 return out->f_op->splice_write(pipe, out, ppos, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200897}
898
Jens Axboe83f91352006-04-02 23:05:09 +0200899/*
900 * Attempt to initiate a splice from a file to a pipe.
901 */
Jens Axboecbb7e572006-04-11 14:57:50 +0200902static long do_splice_to(struct file *in, loff_t *ppos,
903 struct pipe_inode_info *pipe, size_t len,
904 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200905{
Jens Axboe5274f052006-03-30 15:15:30 +0200906 int ret;
907
Jens Axboe49570e92006-04-11 13:56:09 +0200908 if (unlikely(!in->f_op || !in->f_op->splice_read))
Jens Axboe5274f052006-03-30 15:15:30 +0200909 return -EINVAL;
910
Jens Axboe49570e92006-04-11 13:56:09 +0200911 if (unlikely(!(in->f_mode & FMODE_READ)))
Jens Axboe5274f052006-03-30 15:15:30 +0200912 return -EBADF;
913
Jens Axboecbb7e572006-04-11 14:57:50 +0200914 ret = rw_verify_area(READ, in, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +0200915 if (unlikely(ret < 0))
916 return ret;
917
Jens Axboecbb7e572006-04-11 14:57:50 +0200918 return in->f_op->splice_read(in, ppos, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200919}
920
Jens Axboe932cc6d2007-06-21 13:10:21 +0200921/**
922 * splice_direct_to_actor - splices data directly between two non-pipes
923 * @in: file to splice from
924 * @sd: actor information on where to splice to
925 * @actor: handles the data splicing
926 *
927 * Description:
928 * This is a special case helper to splice directly between two
929 * points, without requiring an explicit pipe. Internally an allocated
Randy Dunlap79685b82007-07-27 08:08:51 +0200930 * pipe is cached in the process, and reused during the lifetime of
Jens Axboe932cc6d2007-06-21 13:10:21 +0200931 * that process.
932 *
Jens Axboec66ab6f2007-06-12 21:17:17 +0200933 */
934ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
935 splice_direct_actor *actor)
Jens Axboeb92ce552006-04-11 13:52:07 +0200936{
937 struct pipe_inode_info *pipe;
938 long ret, bytes;
939 umode_t i_mode;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200940 size_t len;
941 int i, flags;
Jens Axboeb92ce552006-04-11 13:52:07 +0200942
943 /*
944 * We require the input being a regular file, as we don't want to
945 * randomly drop data for eg socket -> socket splicing. Use the
946 * piped splicing for that!
947 */
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800948 i_mode = in->f_path.dentry->d_inode->i_mode;
Jens Axboeb92ce552006-04-11 13:52:07 +0200949 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
950 return -EINVAL;
951
952 /*
953 * neither in nor out is a pipe, setup an internal pipe attached to
954 * 'out' and transfer the wanted data from 'in' to 'out' through that
955 */
956 pipe = current->splice_pipe;
Jens Axboe49570e92006-04-11 13:56:09 +0200957 if (unlikely(!pipe)) {
Jens Axboeb92ce552006-04-11 13:52:07 +0200958 pipe = alloc_pipe_info(NULL);
959 if (!pipe)
960 return -ENOMEM;
961
962 /*
963 * We don't have an immediate reader, but we'll read the stuff
Jens Axboe00522fb2006-04-26 14:39:29 +0200964 * out of the pipe right after the splice_to_pipe(). So set
Jens Axboeb92ce552006-04-11 13:52:07 +0200965 * PIPE_READERS appropriately.
966 */
967 pipe->readers = 1;
968
969 current->splice_pipe = pipe;
970 }
971
972 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +0200973 * Do the splice.
Jens Axboeb92ce552006-04-11 13:52:07 +0200974 */
975 ret = 0;
976 bytes = 0;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200977 len = sd->total_len;
978 flags = sd->flags;
979
980 /*
981 * Don't block on output, we have to drain the direct pipe.
982 */
983 sd->flags &= ~SPLICE_F_NONBLOCK;
Jens Axboeb92ce552006-04-11 13:52:07 +0200984
985 while (len) {
Jens Axboe51a92c02007-07-13 14:11:43 +0200986 size_t read_len;
Tom Zanussia82c53a2008-05-09 13:28:36 +0200987 loff_t pos = sd->pos, prev_pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +0200988
Jens Axboebcd4f3a2007-07-16 14:41:49 +0200989 ret = do_splice_to(in, &pos, pipe, len, flags);
Jens Axboe51a92c02007-07-13 14:11:43 +0200990 if (unlikely(ret <= 0))
Jens Axboeb92ce552006-04-11 13:52:07 +0200991 goto out_release;
992
993 read_len = ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200994 sd->total_len = read_len;
Jens Axboeb92ce552006-04-11 13:52:07 +0200995
996 /*
997 * NOTE: nonblocking mode only applies to the input. We
998 * must not do the output in nonblocking mode as then we
999 * could get stuck data in the internal pipe:
1000 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001001 ret = actor(pipe, sd);
Tom Zanussia82c53a2008-05-09 13:28:36 +02001002 if (unlikely(ret <= 0)) {
1003 sd->pos = prev_pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001004 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001005 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001006
1007 bytes += ret;
1008 len -= ret;
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001009 sd->pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001010
Tom Zanussia82c53a2008-05-09 13:28:36 +02001011 if (ret < read_len) {
1012 sd->pos = prev_pos + ret;
Jens Axboe51a92c02007-07-13 14:11:43 +02001013 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001014 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001015 }
1016
Jens Axboe9e971982008-01-29 21:05:57 +01001017done:
Jens Axboeb92ce552006-04-11 13:52:07 +02001018 pipe->nrbufs = pipe->curbuf = 0;
Jens Axboe80848702008-01-30 12:24:48 +01001019 file_accessed(in);
Jens Axboeb92ce552006-04-11 13:52:07 +02001020 return bytes;
1021
1022out_release:
1023 /*
1024 * If we did an incomplete transfer we must release
1025 * the pipe buffers in question:
1026 */
1027 for (i = 0; i < PIPE_BUFFERS; i++) {
1028 struct pipe_buffer *buf = pipe->bufs + i;
1029
1030 if (buf->ops) {
1031 buf->ops->release(pipe, buf);
1032 buf->ops = NULL;
1033 }
1034 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001035
Jens Axboe9e971982008-01-29 21:05:57 +01001036 if (!bytes)
1037 bytes = ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001038
Jens Axboe9e971982008-01-29 21:05:57 +01001039 goto done;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001040}
1041EXPORT_SYMBOL(splice_direct_to_actor);
1042
1043static int direct_splice_actor(struct pipe_inode_info *pipe,
1044 struct splice_desc *sd)
1045{
Jens Axboe6a14b902007-06-14 13:08:55 +02001046 struct file *file = sd->u.file;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001047
1048 return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
1049}
1050
Jens Axboe932cc6d2007-06-21 13:10:21 +02001051/**
1052 * do_splice_direct - splices data directly between two files
1053 * @in: file to splice from
1054 * @ppos: input file offset
1055 * @out: file to splice to
1056 * @len: number of bytes to splice
1057 * @flags: splice modifier flags
1058 *
1059 * Description:
1060 * For use by do_sendfile(). splice can easily emulate sendfile, but
1061 * doing it in the application would incur an extra system call
1062 * (splice in + splice out, as compared to just sendfile()). So this helper
1063 * can splice directly through a process-private pipe.
1064 *
1065 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001066long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
1067 size_t len, unsigned int flags)
1068{
1069 struct splice_desc sd = {
1070 .len = len,
1071 .total_len = len,
1072 .flags = flags,
1073 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +02001074 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +02001075 };
Jens Axboe51a92c02007-07-13 14:11:43 +02001076 long ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001077
1078 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
Jens Axboe51a92c02007-07-13 14:11:43 +02001079 if (ret > 0)
Tom Zanussia82c53a2008-05-09 13:28:36 +02001080 *ppos = sd.pos;
Jens Axboe51a92c02007-07-13 14:11:43 +02001081
Jens Axboec66ab6f2007-06-12 21:17:17 +02001082 return ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001083}
1084
Jens Axboe83f91352006-04-02 23:05:09 +02001085/*
Jens Axboeddac0d32006-11-04 12:49:32 +01001086 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1087 * location, so checking ->i_pipe is not enough to verify that this is a
1088 * pipe.
1089 */
1090static inline struct pipe_inode_info *pipe_info(struct inode *inode)
1091{
1092 if (S_ISFIFO(inode->i_mode))
1093 return inode->i_pipe;
1094
1095 return NULL;
1096}
1097
1098/*
Jens Axboe83f91352006-04-02 23:05:09 +02001099 * Determine where to splice to/from.
1100 */
Ingo Molnar529565d2006-04-10 15:18:58 +02001101static long do_splice(struct file *in, loff_t __user *off_in,
1102 struct file *out, loff_t __user *off_out,
1103 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001104{
Ingo Molnar3a326a22006-04-10 15:18:35 +02001105 struct pipe_inode_info *pipe;
Jens Axboecbb7e572006-04-11 14:57:50 +02001106 loff_t offset, *off;
Jens Axboea4514eb2006-04-19 15:57:05 +02001107 long ret;
Jens Axboe5274f052006-03-30 15:15:30 +02001108
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001109 pipe = pipe_info(in->f_path.dentry->d_inode);
Ingo Molnar529565d2006-04-10 15:18:58 +02001110 if (pipe) {
1111 if (off_in)
1112 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001113 if (off_out) {
1114 if (out->f_op->llseek == no_llseek)
1115 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001116 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001117 return -EFAULT;
Jens Axboecbb7e572006-04-11 14:57:50 +02001118 off = &offset;
1119 } else
1120 off = &out->f_pos;
Ingo Molnar529565d2006-04-10 15:18:58 +02001121
Jens Axboea4514eb2006-04-19 15:57:05 +02001122 ret = do_splice_from(pipe, out, off, len, flags);
1123
1124 if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
1125 ret = -EFAULT;
1126
1127 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001128 }
Jens Axboe5274f052006-03-30 15:15:30 +02001129
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001130 pipe = pipe_info(out->f_path.dentry->d_inode);
Ingo Molnar529565d2006-04-10 15:18:58 +02001131 if (pipe) {
1132 if (off_out)
1133 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001134 if (off_in) {
1135 if (in->f_op->llseek == no_llseek)
1136 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001137 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001138 return -EFAULT;
Jens Axboecbb7e572006-04-11 14:57:50 +02001139 off = &offset;
1140 } else
1141 off = &in->f_pos;
Ingo Molnar529565d2006-04-10 15:18:58 +02001142
Jens Axboea4514eb2006-04-19 15:57:05 +02001143 ret = do_splice_to(in, off, pipe, len, flags);
1144
1145 if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
1146 ret = -EFAULT;
1147
1148 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001149 }
Jens Axboe5274f052006-03-30 15:15:30 +02001150
1151 return -EINVAL;
1152}
1153
Jens Axboe912d35f2006-04-26 10:59:21 +02001154/*
Linus Torvalds75723952007-10-01 13:17:28 -07001155 * Do a copy-from-user while holding the mmap_semaphore for reading, in a
1156 * manner safe from deadlocking with simultaneous mmap() (grabbing mmap_sem
1157 * for writing) and page faulting on the user memory pointed to by src.
1158 * This assumes that we will very rarely hit the partial != 0 path, or this
1159 * will not be a win.
1160 */
1161static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n)
1162{
1163 int partial;
1164
Jens Axboe88119302008-02-08 08:49:14 -08001165 if (!access_ok(VERIFY_READ, src, n))
1166 return -EFAULT;
1167
Linus Torvalds75723952007-10-01 13:17:28 -07001168 pagefault_disable();
1169 partial = __copy_from_user_inatomic(dst, src, n);
1170 pagefault_enable();
1171
1172 /*
1173 * Didn't copy everything, drop the mmap_sem and do a faulting copy
1174 */
1175 if (unlikely(partial)) {
1176 up_read(&current->mm->mmap_sem);
1177 partial = copy_from_user(dst, src, n);
1178 down_read(&current->mm->mmap_sem);
1179 }
1180
1181 return partial;
1182}
1183
1184/*
Jens Axboe912d35f2006-04-26 10:59:21 +02001185 * Map an iov into an array of pages and offset/length tupples. With the
1186 * partial_page structure, we can map several non-contiguous ranges into
1187 * our ones pages[] map instead of splitting that operation into pieces.
1188 * Could easily be exported as a generic helper for other users, in which
1189 * case one would probably want to add a 'max_nr_pages' parameter as well.
1190 */
1191static int get_iovec_page_array(const struct iovec __user *iov,
1192 unsigned int nr_vecs, struct page **pages,
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001193 struct partial_page *partial, int aligned)
Jens Axboe912d35f2006-04-26 10:59:21 +02001194{
1195 int buffers = 0, error = 0;
1196
Jens Axboe912d35f2006-04-26 10:59:21 +02001197 down_read(&current->mm->mmap_sem);
1198
1199 while (nr_vecs) {
1200 unsigned long off, npages;
Linus Torvalds75723952007-10-01 13:17:28 -07001201 struct iovec entry;
Jens Axboe912d35f2006-04-26 10:59:21 +02001202 void __user *base;
1203 size_t len;
1204 int i;
1205
Linus Torvalds75723952007-10-01 13:17:28 -07001206 error = -EFAULT;
1207 if (copy_from_user_mmap_sem(&entry, iov, sizeof(entry)))
Jens Axboe912d35f2006-04-26 10:59:21 +02001208 break;
Linus Torvalds75723952007-10-01 13:17:28 -07001209
1210 base = entry.iov_base;
1211 len = entry.iov_len;
Jens Axboe912d35f2006-04-26 10:59:21 +02001212
1213 /*
1214 * Sanity check this iovec. 0 read succeeds.
1215 */
Linus Torvalds75723952007-10-01 13:17:28 -07001216 error = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +02001217 if (unlikely(!len))
1218 break;
1219 error = -EFAULT;
Bastian Blank712a30e2008-02-10 16:47:57 +02001220 if (!access_ok(VERIFY_READ, base, len))
Jens Axboe912d35f2006-04-26 10:59:21 +02001221 break;
1222
1223 /*
1224 * Get this base offset and number of pages, then map
1225 * in the user pages.
1226 */
1227 off = (unsigned long) base & ~PAGE_MASK;
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001228
1229 /*
1230 * If asked for alignment, the offset must be zero and the
1231 * length a multiple of the PAGE_SIZE.
1232 */
1233 error = -EINVAL;
1234 if (aligned && (off || len & ~PAGE_MASK))
1235 break;
1236
Jens Axboe912d35f2006-04-26 10:59:21 +02001237 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1238 if (npages > PIPE_BUFFERS - buffers)
1239 npages = PIPE_BUFFERS - buffers;
1240
1241 error = get_user_pages(current, current->mm,
1242 (unsigned long) base, npages, 0, 0,
1243 &pages[buffers], NULL);
1244
1245 if (unlikely(error <= 0))
1246 break;
1247
1248 /*
1249 * Fill this contiguous range into the partial page map.
1250 */
1251 for (i = 0; i < error; i++) {
Jens Axboe75914892006-05-02 12:57:18 +02001252 const int plen = min_t(size_t, len, PAGE_SIZE - off);
Jens Axboe912d35f2006-04-26 10:59:21 +02001253
1254 partial[buffers].offset = off;
1255 partial[buffers].len = plen;
1256
1257 off = 0;
1258 len -= plen;
1259 buffers++;
1260 }
1261
1262 /*
1263 * We didn't complete this iov, stop here since it probably
1264 * means we have to move some of this into a pipe to
1265 * be able to continue.
1266 */
1267 if (len)
1268 break;
1269
1270 /*
1271 * Don't continue if we mapped fewer pages than we asked for,
1272 * or if we mapped the max number of pages that we have
1273 * room for.
1274 */
1275 if (error < npages || buffers == PIPE_BUFFERS)
1276 break;
1277
1278 nr_vecs--;
1279 iov++;
1280 }
1281
1282 up_read(&current->mm->mmap_sem);
1283
1284 if (buffers)
1285 return buffers;
1286
1287 return error;
1288}
1289
Jens Axboe6a14b902007-06-14 13:08:55 +02001290static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1291 struct splice_desc *sd)
1292{
1293 char *src;
1294 int ret;
1295
Jens Axboecac36bb02007-06-14 13:10:48 +02001296 ret = buf->ops->confirm(pipe, buf);
Jens Axboe6a14b902007-06-14 13:08:55 +02001297 if (unlikely(ret))
1298 return ret;
1299
1300 /*
1301 * See if we can use the atomic maps, by prefaulting in the
1302 * pages and doing an atomic copy
1303 */
1304 if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) {
1305 src = buf->ops->map(pipe, buf, 1);
1306 ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset,
1307 sd->len);
1308 buf->ops->unmap(pipe, buf, src);
1309 if (!ret) {
1310 ret = sd->len;
1311 goto out;
1312 }
1313 }
1314
1315 /*
1316 * No dice, use slow non-atomic map and copy
1317 */
1318 src = buf->ops->map(pipe, buf, 0);
1319
1320 ret = sd->len;
1321 if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len))
1322 ret = -EFAULT;
1323
Jens Axboe6866bef2007-10-16 10:01:29 +02001324 buf->ops->unmap(pipe, buf, src);
Jens Axboe6a14b902007-06-14 13:08:55 +02001325out:
1326 if (ret > 0)
1327 sd->u.userptr += ret;
Jens Axboe6a14b902007-06-14 13:08:55 +02001328 return ret;
1329}
1330
1331/*
1332 * For lack of a better implementation, implement vmsplice() to userspace
1333 * as a simple copy of the pipes pages to the user iov.
1334 */
1335static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
1336 unsigned long nr_segs, unsigned int flags)
1337{
1338 struct pipe_inode_info *pipe;
1339 struct splice_desc sd;
1340 ssize_t size;
1341 int error;
1342 long ret;
1343
1344 pipe = pipe_info(file->f_path.dentry->d_inode);
1345 if (!pipe)
1346 return -EBADF;
1347
1348 if (pipe->inode)
1349 mutex_lock(&pipe->inode->i_mutex);
1350
1351 error = ret = 0;
1352 while (nr_segs) {
1353 void __user *base;
1354 size_t len;
1355
1356 /*
1357 * Get user address base and length for this iovec.
1358 */
1359 error = get_user(base, &iov->iov_base);
1360 if (unlikely(error))
1361 break;
1362 error = get_user(len, &iov->iov_len);
1363 if (unlikely(error))
1364 break;
1365
1366 /*
1367 * Sanity check this iovec. 0 read succeeds.
1368 */
1369 if (unlikely(!len))
1370 break;
1371 if (unlikely(!base)) {
1372 error = -EFAULT;
1373 break;
1374 }
1375
Jens Axboe88119302008-02-08 08:49:14 -08001376 if (unlikely(!access_ok(VERIFY_WRITE, base, len))) {
1377 error = -EFAULT;
1378 break;
1379 }
1380
Jens Axboe6a14b902007-06-14 13:08:55 +02001381 sd.len = 0;
1382 sd.total_len = len;
1383 sd.flags = flags;
1384 sd.u.userptr = base;
1385 sd.pos = 0;
1386
1387 size = __splice_from_pipe(pipe, &sd, pipe_to_user);
1388 if (size < 0) {
1389 if (!ret)
1390 ret = size;
1391
1392 break;
1393 }
1394
1395 ret += size;
1396
1397 if (size < len)
1398 break;
1399
1400 nr_segs--;
1401 iov++;
1402 }
1403
1404 if (pipe->inode)
1405 mutex_unlock(&pipe->inode->i_mutex);
1406
1407 if (!ret)
1408 ret = error;
1409
1410 return ret;
1411}
1412
Jens Axboe912d35f2006-04-26 10:59:21 +02001413/*
1414 * vmsplice splices a user address range into a pipe. It can be thought of
1415 * as splice-from-memory, where the regular splice is splice-from-file (or
1416 * to file). In both cases the output is a pipe, naturally.
Jens Axboe912d35f2006-04-26 10:59:21 +02001417 */
Jens Axboe6a14b902007-06-14 13:08:55 +02001418static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
1419 unsigned long nr_segs, unsigned int flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001420{
Jens Axboeddac0d32006-11-04 12:49:32 +01001421 struct pipe_inode_info *pipe;
Jens Axboe912d35f2006-04-26 10:59:21 +02001422 struct page *pages[PIPE_BUFFERS];
1423 struct partial_page partial[PIPE_BUFFERS];
1424 struct splice_pipe_desc spd = {
1425 .pages = pages,
1426 .partial = partial,
1427 .flags = flags,
1428 .ops = &user_page_pipe_buf_ops,
Jens Axboebbdfc2f2007-11-06 23:29:47 -08001429 .spd_release = spd_release_page,
Jens Axboe912d35f2006-04-26 10:59:21 +02001430 };
1431
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001432 pipe = pipe_info(file->f_path.dentry->d_inode);
Jens Axboeddac0d32006-11-04 12:49:32 +01001433 if (!pipe)
Jens Axboe912d35f2006-04-26 10:59:21 +02001434 return -EBADF;
Jens Axboe912d35f2006-04-26 10:59:21 +02001435
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001436 spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
1437 flags & SPLICE_F_GIFT);
Jens Axboe912d35f2006-04-26 10:59:21 +02001438 if (spd.nr_pages <= 0)
1439 return spd.nr_pages;
1440
Jens Axboe00522fb2006-04-26 14:39:29 +02001441 return splice_to_pipe(pipe, &spd);
Jens Axboe912d35f2006-04-26 10:59:21 +02001442}
1443
Jens Axboe6a14b902007-06-14 13:08:55 +02001444/*
1445 * Note that vmsplice only really supports true splicing _from_ user memory
1446 * to a pipe, not the other way around. Splicing from user memory is a simple
1447 * operation that can be supported without any funky alignment restrictions
1448 * or nasty vm tricks. We simply map in the user memory and fill them into
1449 * a pipe. The reverse isn't quite as easy, though. There are two possible
1450 * solutions for that:
1451 *
1452 * - memcpy() the data internally, at which point we might as well just
1453 * do a regular read() on the buffer anyway.
1454 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1455 * has restriction limitations on both ends of the pipe).
1456 *
1457 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1458 *
1459 */
Jens Axboe912d35f2006-04-26 10:59:21 +02001460asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
1461 unsigned long nr_segs, unsigned int flags)
1462{
1463 struct file *file;
1464 long error;
1465 int fput;
1466
Jens Axboe6a14b902007-06-14 13:08:55 +02001467 if (unlikely(nr_segs > UIO_MAXIOV))
1468 return -EINVAL;
1469 else if (unlikely(!nr_segs))
1470 return 0;
1471
Jens Axboe912d35f2006-04-26 10:59:21 +02001472 error = -EBADF;
1473 file = fget_light(fd, &fput);
1474 if (file) {
1475 if (file->f_mode & FMODE_WRITE)
Jens Axboe6a14b902007-06-14 13:08:55 +02001476 error = vmsplice_to_pipe(file, iov, nr_segs, flags);
1477 else if (file->f_mode & FMODE_READ)
1478 error = vmsplice_to_user(file, iov, nr_segs, flags);
Jens Axboe912d35f2006-04-26 10:59:21 +02001479
1480 fput_light(file, fput);
1481 }
1482
1483 return error;
1484}
1485
Ingo Molnar529565d2006-04-10 15:18:58 +02001486asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
1487 int fd_out, loff_t __user *off_out,
1488 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001489{
1490 long error;
1491 struct file *in, *out;
1492 int fput_in, fput_out;
1493
1494 if (unlikely(!len))
1495 return 0;
1496
1497 error = -EBADF;
Ingo Molnar529565d2006-04-10 15:18:58 +02001498 in = fget_light(fd_in, &fput_in);
Jens Axboe5274f052006-03-30 15:15:30 +02001499 if (in) {
1500 if (in->f_mode & FMODE_READ) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001501 out = fget_light(fd_out, &fput_out);
Jens Axboe5274f052006-03-30 15:15:30 +02001502 if (out) {
1503 if (out->f_mode & FMODE_WRITE)
Ingo Molnar529565d2006-04-10 15:18:58 +02001504 error = do_splice(in, off_in,
1505 out, off_out,
1506 len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001507 fput_light(out, fput_out);
1508 }
1509 }
1510
1511 fput_light(in, fput_in);
1512 }
1513
1514 return error;
1515}
Jens Axboe70524492006-04-11 15:51:17 +02001516
1517/*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001518 * Make sure there's data to read. Wait for input if we can, otherwise
1519 * return an appropriate error.
1520 */
1521static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1522{
1523 int ret;
1524
1525 /*
1526 * Check ->nrbufs without the inode lock first. This function
1527 * is speculative anyways, so missing one is ok.
1528 */
1529 if (pipe->nrbufs)
1530 return 0;
1531
1532 ret = 0;
1533 mutex_lock(&pipe->inode->i_mutex);
1534
1535 while (!pipe->nrbufs) {
1536 if (signal_pending(current)) {
1537 ret = -ERESTARTSYS;
1538 break;
1539 }
1540 if (!pipe->writers)
1541 break;
1542 if (!pipe->waiting_writers) {
1543 if (flags & SPLICE_F_NONBLOCK) {
1544 ret = -EAGAIN;
1545 break;
1546 }
1547 }
1548 pipe_wait(pipe);
1549 }
1550
1551 mutex_unlock(&pipe->inode->i_mutex);
1552 return ret;
1553}
1554
1555/*
1556 * Make sure there's writeable room. Wait for room if we can, otherwise
1557 * return an appropriate error.
1558 */
1559static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1560{
1561 int ret;
1562
1563 /*
1564 * Check ->nrbufs without the inode lock first. This function
1565 * is speculative anyways, so missing one is ok.
1566 */
1567 if (pipe->nrbufs < PIPE_BUFFERS)
1568 return 0;
1569
1570 ret = 0;
1571 mutex_lock(&pipe->inode->i_mutex);
1572
1573 while (pipe->nrbufs >= PIPE_BUFFERS) {
1574 if (!pipe->readers) {
1575 send_sig(SIGPIPE, current, 0);
1576 ret = -EPIPE;
1577 break;
1578 }
1579 if (flags & SPLICE_F_NONBLOCK) {
1580 ret = -EAGAIN;
1581 break;
1582 }
1583 if (signal_pending(current)) {
1584 ret = -ERESTARTSYS;
1585 break;
1586 }
1587 pipe->waiting_writers++;
1588 pipe_wait(pipe);
1589 pipe->waiting_writers--;
1590 }
1591
1592 mutex_unlock(&pipe->inode->i_mutex);
1593 return ret;
1594}
1595
1596/*
Jens Axboe70524492006-04-11 15:51:17 +02001597 * Link contents of ipipe to opipe.
1598 */
1599static int link_pipe(struct pipe_inode_info *ipipe,
1600 struct pipe_inode_info *opipe,
1601 size_t len, unsigned int flags)
1602{
1603 struct pipe_buffer *ibuf, *obuf;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001604 int ret = 0, i = 0, nbuf;
Jens Axboe70524492006-04-11 15:51:17 +02001605
1606 /*
1607 * Potential ABBA deadlock, work around it by ordering lock
1608 * grabbing by inode address. Otherwise two different processes
1609 * could deadlock (one doing tee from A -> B, the other from B -> A).
1610 */
Mark Fasheh62752ee2006-10-17 10:31:38 +02001611 inode_double_lock(ipipe->inode, opipe->inode);
Jens Axboe70524492006-04-11 15:51:17 +02001612
Jens Axboeaadd06e2006-07-10 11:00:01 +02001613 do {
Jens Axboe70524492006-04-11 15:51:17 +02001614 if (!opipe->readers) {
1615 send_sig(SIGPIPE, current, 0);
1616 if (!ret)
1617 ret = -EPIPE;
1618 break;
1619 }
Jens Axboe70524492006-04-11 15:51:17 +02001620
1621 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001622 * If we have iterated all input buffers or ran out of
1623 * output room, break.
Jens Axboe70524492006-04-11 15:51:17 +02001624 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001625 if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS)
Jens Axboe70524492006-04-11 15:51:17 +02001626 break;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001627
1628 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
1629 nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
1630
Jens Axboe2a27250e2006-04-19 15:56:40 +02001631 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001632 * Get a reference to this pipe buffer,
1633 * so we can copy the contents over.
Jens Axboe2a27250e2006-04-19 15:56:40 +02001634 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001635 ibuf->ops->get(ipipe, ibuf);
Jens Axboe70524492006-04-11 15:51:17 +02001636
Jens Axboeaadd06e2006-07-10 11:00:01 +02001637 obuf = opipe->bufs + nbuf;
1638 *obuf = *ibuf;
Jens Axboe70524492006-04-11 15:51:17 +02001639
Jens Axboeaadd06e2006-07-10 11:00:01 +02001640 /*
1641 * Don't inherit the gift flag, we need to
1642 * prevent multiple steals of this page.
1643 */
1644 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1645
1646 if (obuf->len > len)
1647 obuf->len = len;
1648
1649 opipe->nrbufs++;
1650 ret += obuf->len;
1651 len -= obuf->len;
1652 i++;
1653 } while (len);
Jens Axboe70524492006-04-11 15:51:17 +02001654
Jens Axboe02cf01a2008-02-20 10:34:51 +01001655 /*
1656 * return EAGAIN if we have the potential of some data in the
1657 * future, otherwise just return 0
1658 */
1659 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1660 ret = -EAGAIN;
1661
Mark Fasheh62752ee2006-10-17 10:31:38 +02001662 inode_double_unlock(ipipe->inode, opipe->inode);
Jens Axboe70524492006-04-11 15:51:17 +02001663
Jens Axboeaadd06e2006-07-10 11:00:01 +02001664 /*
1665 * If we put data in the output pipe, wakeup any potential readers.
1666 */
1667 if (ret > 0) {
Jens Axboe70524492006-04-11 15:51:17 +02001668 smp_mb();
1669 if (waitqueue_active(&opipe->wait))
1670 wake_up_interruptible(&opipe->wait);
1671 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1672 }
1673
1674 return ret;
1675}
1676
1677/*
1678 * This is a tee(1) implementation that works on pipes. It doesn't copy
1679 * any data, it simply references the 'in' pages on the 'out' pipe.
1680 * The 'flags' used are the SPLICE_F_* variants, currently the only
1681 * applicable one is SPLICE_F_NONBLOCK.
1682 */
1683static long do_tee(struct file *in, struct file *out, size_t len,
1684 unsigned int flags)
1685{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001686 struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode);
1687 struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001688 int ret = -EINVAL;
Jens Axboe70524492006-04-11 15:51:17 +02001689
1690 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001691 * Duplicate the contents of ipipe to opipe without actually
1692 * copying the data.
Jens Axboe70524492006-04-11 15:51:17 +02001693 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001694 if (ipipe && opipe && ipipe != opipe) {
1695 /*
1696 * Keep going, unless we encounter an error. The ipipe/opipe
1697 * ordering doesn't really matter.
1698 */
1699 ret = link_ipipe_prep(ipipe, flags);
1700 if (!ret) {
1701 ret = link_opipe_prep(opipe, flags);
Jens Axboe02cf01a2008-02-20 10:34:51 +01001702 if (!ret)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001703 ret = link_pipe(ipipe, opipe, len, flags);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001704 }
1705 }
Jens Axboe70524492006-04-11 15:51:17 +02001706
Jens Axboeaadd06e2006-07-10 11:00:01 +02001707 return ret;
Jens Axboe70524492006-04-11 15:51:17 +02001708}
1709
1710asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
1711{
1712 struct file *in;
1713 int error, fput_in;
1714
1715 if (unlikely(!len))
1716 return 0;
1717
1718 error = -EBADF;
1719 in = fget_light(fdin, &fput_in);
1720 if (in) {
1721 if (in->f_mode & FMODE_READ) {
1722 int fput_out;
1723 struct file *out = fget_light(fdout, &fput_out);
1724
1725 if (out) {
1726 if (out->f_mode & FMODE_WRITE)
1727 error = do_tee(in, out, len, flags);
1728 fput_light(out, fput_out);
1729 }
1730 }
1731 fput_light(in, fput_in);
1732 }
1733
1734 return error;
1735}