blob: 56b802bfbfa4879021cc2af03f175e69cec621d8 [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 Axboe9e94cd42006-06-20 15:01:12 +020061 if (PagePrivate(page))
Nick Piggin2ae88142006-10-28 10:38:23 -070062 try_to_release_page(page, GFP_KERNEL);
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 */
78 unlock_page(page);
79 return 1;
Jens Axboe5abc97a2006-03-30 15:16:46 +020080}
81
Jens Axboe76ad4d12006-05-03 10:41:33 +020082static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +020083 struct pipe_buffer *buf)
84{
85 page_cache_release(buf->page);
Jens Axboe14328732006-05-03 10:35:26 +020086 buf->flags &= ~PIPE_BUF_FLAG_LRU;
Jens Axboe5274f052006-03-30 15:15:30 +020087}
88
Jens Axboe08457182007-06-12 20:51:32 +020089/*
90 * Check whether the contents of buf is OK to access. Since the content
91 * is a page cache page, IO may be in flight.
92 */
Jens Axboecac36bb02007-06-14 13:10:48 +020093static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
94 struct pipe_buffer *buf)
Jens Axboe5274f052006-03-30 15:15:30 +020095{
96 struct page *page = buf->page;
Jens Axboe49d0b212006-04-10 09:04:41 +020097 int err;
Jens Axboe5274f052006-03-30 15:15:30 +020098
99 if (!PageUptodate(page)) {
Jens Axboe49d0b212006-04-10 09:04:41 +0200100 lock_page(page);
101
102 /*
103 * Page got truncated/unhashed. This will cause a 0-byte
Ingo Molnar73d62d82006-04-11 13:57:21 +0200104 * splice, if this is the first page.
Jens Axboe49d0b212006-04-10 09:04:41 +0200105 */
106 if (!page->mapping) {
107 err = -ENODATA;
108 goto error;
109 }
110
111 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +0200112 * Uh oh, read-error from disk.
Jens Axboe49d0b212006-04-10 09:04:41 +0200113 */
114 if (!PageUptodate(page)) {
115 err = -EIO;
116 goto error;
117 }
118
119 /*
Jens Axboef84d7512006-05-01 19:59:03 +0200120 * Page is ok afterall, we are done.
Jens Axboe49d0b212006-04-10 09:04:41 +0200121 */
Jens Axboe5274f052006-03-30 15:15:30 +0200122 unlock_page(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200123 }
124
Jens Axboef84d7512006-05-01 19:59:03 +0200125 return 0;
Jens Axboe49d0b212006-04-10 09:04:41 +0200126error:
127 unlock_page(page);
Jens Axboef84d7512006-05-01 19:59:03 +0200128 return err;
Jens Axboe70524492006-04-11 15:51:17 +0200129}
130
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800131static const struct pipe_buf_operations page_cache_pipe_buf_ops = {
Jens Axboe5274f052006-03-30 15:15:30 +0200132 .can_merge = 0,
Jens Axboef84d7512006-05-01 19:59:03 +0200133 .map = generic_pipe_buf_map,
134 .unmap = generic_pipe_buf_unmap,
Jens Axboecac36bb02007-06-14 13:10:48 +0200135 .confirm = page_cache_pipe_buf_confirm,
Jens Axboe5274f052006-03-30 15:15:30 +0200136 .release = page_cache_pipe_buf_release,
Jens Axboe5abc97a2006-03-30 15:16:46 +0200137 .steal = page_cache_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200138 .get = generic_pipe_buf_get,
Jens Axboe5274f052006-03-30 15:15:30 +0200139};
140
Jens Axboe912d35f2006-04-26 10:59:21 +0200141static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
142 struct pipe_buffer *buf)
143{
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200144 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
145 return 1;
146
Jens Axboe14328732006-05-03 10:35:26 +0200147 buf->flags |= PIPE_BUF_FLAG_LRU;
Jens Axboe330ab712006-05-02 15:29:57 +0200148 return generic_pipe_buf_steal(pipe, buf);
Jens Axboe912d35f2006-04-26 10:59:21 +0200149}
150
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800151static const struct pipe_buf_operations user_page_pipe_buf_ops = {
Jens Axboe912d35f2006-04-26 10:59:21 +0200152 .can_merge = 0,
Jens Axboef84d7512006-05-01 19:59:03 +0200153 .map = generic_pipe_buf_map,
154 .unmap = generic_pipe_buf_unmap,
Jens Axboecac36bb02007-06-14 13:10:48 +0200155 .confirm = generic_pipe_buf_confirm,
Jens Axboe912d35f2006-04-26 10:59:21 +0200156 .release = page_cache_pipe_buf_release,
157 .steal = user_page_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200158 .get = generic_pipe_buf_get,
Jens Axboe912d35f2006-04-26 10:59:21 +0200159};
160
Jens Axboe932cc6d2007-06-21 13:10:21 +0200161/**
162 * splice_to_pipe - fill passed data into a pipe
163 * @pipe: pipe to fill
164 * @spd: data to fill
165 *
166 * Description:
Randy Dunlap79685b82007-07-27 08:08:51 +0200167 * @spd contains a map of pages and len/offset tuples, along with
Jens Axboe932cc6d2007-06-21 13:10:21 +0200168 * the struct pipe_buf_operations associated with these pages. This
169 * function will link that data to the pipe.
170 *
Jens Axboe83f91352006-04-02 23:05:09 +0200171 */
Jens Axboed6b29d72007-06-04 09:59:47 +0200172ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
173 struct splice_pipe_desc *spd)
Jens Axboe5274f052006-03-30 15:15:30 +0200174{
Jens Axboe00de00b2007-06-15 13:14:22 +0200175 unsigned int spd_pages = spd->nr_pages;
Jens Axboe912d35f2006-04-26 10:59:21 +0200176 int ret, do_wakeup, page_nr;
Jens Axboe5274f052006-03-30 15:15:30 +0200177
178 ret = 0;
179 do_wakeup = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +0200180 page_nr = 0;
Jens Axboe5274f052006-03-30 15:15:30 +0200181
Ingo Molnar3a326a22006-04-10 15:18:35 +0200182 if (pipe->inode)
183 mutex_lock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200184
Jens Axboe5274f052006-03-30 15:15:30 +0200185 for (;;) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200186 if (!pipe->readers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200187 send_sig(SIGPIPE, current, 0);
188 if (!ret)
189 ret = -EPIPE;
190 break;
191 }
192
Jens Axboe6f767b02006-04-11 13:53:56 +0200193 if (pipe->nrbufs < PIPE_BUFFERS) {
194 int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
Ingo Molnar3a326a22006-04-10 15:18:35 +0200195 struct pipe_buffer *buf = pipe->bufs + newbuf;
Jens Axboe5274f052006-03-30 15:15:30 +0200196
Jens Axboe912d35f2006-04-26 10:59:21 +0200197 buf->page = spd->pages[page_nr];
198 buf->offset = spd->partial[page_nr].offset;
199 buf->len = spd->partial[page_nr].len;
Jens Axboe497f9622007-06-11 12:00:45 +0200200 buf->private = spd->partial[page_nr].private;
Jens Axboe912d35f2006-04-26 10:59:21 +0200201 buf->ops = spd->ops;
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200202 if (spd->flags & SPLICE_F_GIFT)
203 buf->flags |= PIPE_BUF_FLAG_GIFT;
204
Jens Axboe6f767b02006-04-11 13:53:56 +0200205 pipe->nrbufs++;
Jens Axboe912d35f2006-04-26 10:59:21 +0200206 page_nr++;
207 ret += buf->len;
208
Jens Axboe6f767b02006-04-11 13:53:56 +0200209 if (pipe->inode)
210 do_wakeup = 1;
Jens Axboe5274f052006-03-30 15:15:30 +0200211
Jens Axboe912d35f2006-04-26 10:59:21 +0200212 if (!--spd->nr_pages)
Jens Axboe5274f052006-03-30 15:15:30 +0200213 break;
Jens Axboe6f767b02006-04-11 13:53:56 +0200214 if (pipe->nrbufs < PIPE_BUFFERS)
Jens Axboe5274f052006-03-30 15:15:30 +0200215 continue;
216
217 break;
218 }
219
Jens Axboe912d35f2006-04-26 10:59:21 +0200220 if (spd->flags & SPLICE_F_NONBLOCK) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700221 if (!ret)
222 ret = -EAGAIN;
223 break;
224 }
225
Jens Axboe5274f052006-03-30 15:15:30 +0200226 if (signal_pending(current)) {
227 if (!ret)
228 ret = -ERESTARTSYS;
229 break;
230 }
231
232 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200233 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200234 if (waitqueue_active(&pipe->wait))
235 wake_up_interruptible_sync(&pipe->wait);
236 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
Jens Axboe5274f052006-03-30 15:15:30 +0200237 do_wakeup = 0;
238 }
239
Ingo Molnar3a326a22006-04-10 15:18:35 +0200240 pipe->waiting_writers++;
241 pipe_wait(pipe);
242 pipe->waiting_writers--;
Jens Axboe5274f052006-03-30 15:15:30 +0200243 }
244
Jens Axboe02676e52007-06-15 13:16:13 +0200245 if (pipe->inode) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200246 mutex_unlock(&pipe->inode->i_mutex);
Jens Axboe5274f052006-03-30 15:15:30 +0200247
Jens Axboe02676e52007-06-15 13:16:13 +0200248 if (do_wakeup) {
249 smp_mb();
250 if (waitqueue_active(&pipe->wait))
251 wake_up_interruptible(&pipe->wait);
252 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
253 }
Jens Axboe5274f052006-03-30 15:15:30 +0200254 }
255
Jens Axboe00de00b2007-06-15 13:14:22 +0200256 while (page_nr < spd_pages)
Jens Axboe912d35f2006-04-26 10:59:21 +0200257 page_cache_release(spd->pages[page_nr++]);
Jens Axboe5274f052006-03-30 15:15:30 +0200258
259 return ret;
260}
261
Ingo Molnar3a326a22006-04-10 15:18:35 +0200262static int
Jens Axboecbb7e572006-04-11 14:57:50 +0200263__generic_file_splice_read(struct file *in, loff_t *ppos,
264 struct pipe_inode_info *pipe, size_t len,
265 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200266{
267 struct address_space *mapping = in->f_mapping;
Fengguang Wud8983912007-07-19 01:48:06 -0700268 unsigned int loff, nr_pages, req_pages;
Jens Axboe16c523d2006-04-10 09:03:58 +0200269 struct page *pages[PIPE_BUFFERS];
Jens Axboe912d35f2006-04-26 10:59:21 +0200270 struct partial_page partial[PIPE_BUFFERS];
Jens Axboe5274f052006-03-30 15:15:30 +0200271 struct page *page;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200272 pgoff_t index, end_index;
273 loff_t isize;
Jens Axboeeb207962006-04-27 11:05:22 +0200274 int error, page_nr;
Jens Axboe912d35f2006-04-26 10:59:21 +0200275 struct splice_pipe_desc spd = {
276 .pages = pages,
277 .partial = partial,
278 .flags = flags,
279 .ops = &page_cache_pipe_buf_ops,
280 };
Jens Axboe5274f052006-03-30 15:15:30 +0200281
Jens Axboecbb7e572006-04-11 14:57:50 +0200282 index = *ppos >> PAGE_CACHE_SHIFT;
Jens Axboe912d35f2006-04-26 10:59:21 +0200283 loff = *ppos & ~PAGE_CACHE_MASK;
Fengguang Wud8983912007-07-19 01:48:06 -0700284 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
285 nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS);
Jens Axboe5274f052006-03-30 15:15:30 +0200286
287 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200288 * Lookup the (hopefully) full range of pages we need.
289 */
290 spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages);
Fengguang Wu431a48202007-07-19 01:48:05 -0700291 index += spd.nr_pages;
Jens Axboeeb207962006-04-27 11:05:22 +0200292
293 /*
294 * If find_get_pages_contig() returned fewer pages than we needed,
Fengguang Wu431a48202007-07-19 01:48:05 -0700295 * readahead/allocate the rest and fill in the holes.
Jens Axboeeb207962006-04-27 11:05:22 +0200296 */
Fengguang Wu431a48202007-07-19 01:48:05 -0700297 if (spd.nr_pages < nr_pages)
Rusty Russellcf914a72007-07-19 01:48:08 -0700298 page_cache_sync_readahead(mapping, &in->f_ra, in,
299 index, req_pages - spd.nr_pages);
Fengguang Wu431a48202007-07-19 01:48:05 -0700300
Jens Axboe932cc6d2007-06-21 13:10:21 +0200301 error = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200302 while (spd.nr_pages < nr_pages) {
303 /*
304 * Page could be there, find_get_pages_contig() breaks on
305 * the first hole.
306 */
307 page = find_get_page(mapping, index);
308 if (!page) {
Jens Axboee27dedd2006-05-01 19:59:54 +0200309 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200310 * page didn't exist, allocate one.
311 */
312 page = page_cache_alloc_cold(mapping);
313 if (!page)
314 break;
315
316 error = add_to_page_cache_lru(page, mapping, index,
Nick Piggin2ae88142006-10-28 10:38:23 -0700317 GFP_KERNEL);
Jens Axboeeb207962006-04-27 11:05:22 +0200318 if (unlikely(error)) {
319 page_cache_release(page);
Jens Axboea0548872006-05-03 10:58:22 +0200320 if (error == -EEXIST)
321 continue;
Jens Axboeeb207962006-04-27 11:05:22 +0200322 break;
323 }
324 /*
325 * add_to_page_cache() locks the page, unlock it
326 * to avoid convoluting the logic below even more.
327 */
328 unlock_page(page);
329 }
330
331 pages[spd.nr_pages++] = page;
332 index++;
333 }
334
335 /*
336 * Now loop over the map and see if we need to start IO on any
337 * pages, fill in the partial map, etc.
338 */
339 index = *ppos >> PAGE_CACHE_SHIFT;
340 nr_pages = spd.nr_pages;
341 spd.nr_pages = 0;
342 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
Jens Axboe82aa5d62006-04-20 13:05:48 +0200343 unsigned int this_len;
344
345 if (!len)
346 break;
347
348 /*
349 * this_len is the max we'll use from this page
350 */
Andrew Mortonba5f5d92006-04-25 15:33:34 +0200351 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
Jens Axboeeb207962006-04-27 11:05:22 +0200352 page = pages[page_nr];
Jens Axboe7480a902006-04-11 13:52:47 +0200353
Fengguang Wua08a1662007-07-19 01:48:03 -0700354 if (PageReadahead(page))
Rusty Russellcf914a72007-07-19 01:48:08 -0700355 page_cache_async_readahead(mapping, &in->f_ra, in,
Fengguang Wud8983912007-07-19 01:48:06 -0700356 page, index, req_pages - page_nr);
Fengguang Wua08a1662007-07-19 01:48:03 -0700357
Jens Axboe7480a902006-04-11 13:52:47 +0200358 /*
359 * If the page isn't uptodate, we may need to start io on it
360 */
361 if (!PageUptodate(page)) {
Jens Axboec4f895c2006-04-19 15:56:12 +0200362 /*
363 * If in nonblock mode then dont block on waiting
364 * for an in-flight io page
365 */
Fengguang Wu9ae9d682007-05-08 08:44:36 +0200366 if (flags & SPLICE_F_NONBLOCK) {
367 if (TestSetPageLocked(page))
368 break;
369 } else
370 lock_page(page);
Jens Axboe7480a902006-04-11 13:52:47 +0200371
372 /*
373 * page was truncated, stop here. if this isn't the
374 * first page, we'll just complete what we already
375 * added
376 */
377 if (!page->mapping) {
378 unlock_page(page);
Jens Axboe7480a902006-04-11 13:52:47 +0200379 break;
380 }
381 /*
382 * page was already under io and is now done, great
383 */
384 if (PageUptodate(page)) {
385 unlock_page(page);
386 goto fill_it;
387 }
388
Jens Axboe7480a902006-04-11 13:52:47 +0200389 /*
390 * need to read in the page
391 */
392 error = mapping->a_ops->readpage(in, page);
Jens Axboe7480a902006-04-11 13:52:47 +0200393 if (unlikely(error)) {
Jens Axboeeb207962006-04-27 11:05:22 +0200394 /*
395 * We really should re-lookup the page here,
396 * but it complicates things a lot. Instead
397 * lets just do what we already stored, and
398 * we'll get it the next time we are called.
399 */
Jens Axboe7480a902006-04-11 13:52:47 +0200400 if (error == AOP_TRUNCATED_PAGE)
Jens Axboeeb207962006-04-27 11:05:22 +0200401 error = 0;
402
Jens Axboe7480a902006-04-11 13:52:47 +0200403 break;
404 }
Jens Axboe620a3242007-06-07 09:39:42 +0200405 }
406fill_it:
407 /*
408 * i_size must be checked after PageUptodate.
409 */
410 isize = i_size_read(mapping->host);
411 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
412 if (unlikely(!isize || index > end_index))
413 break;
414
415 /*
416 * if this is the last page, see if we need to shrink
417 * the length and stop
418 */
419 if (end_index == index) {
420 unsigned int plen;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200421
422 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200423 * max good bytes in this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200424 */
Jens Axboe620a3242007-06-07 09:39:42 +0200425 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
426 if (plen <= loff)
Jens Axboe91ad66e2006-04-19 15:55:10 +0200427 break;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200428
429 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200430 * force quit after adding this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200431 */
Jens Axboe620a3242007-06-07 09:39:42 +0200432 this_len = min(this_len, plen - loff);
433 len = this_len;
Jens Axboe7480a902006-04-11 13:52:47 +0200434 }
Jens Axboe620a3242007-06-07 09:39:42 +0200435
Jens Axboeeb207962006-04-27 11:05:22 +0200436 partial[page_nr].offset = loff;
437 partial[page_nr].len = this_len;
Jens Axboe82aa5d62006-04-20 13:05:48 +0200438 len -= this_len;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200439 loff = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200440 spd.nr_pages++;
441 index++;
Jens Axboe5274f052006-03-30 15:15:30 +0200442 }
443
Jens Axboeeb207962006-04-27 11:05:22 +0200444 /*
Hugh Dickins475ecad2007-06-07 09:36:00 +0200445 * Release any pages at the end, if we quit early. 'page_nr' is how far
Jens Axboeeb207962006-04-27 11:05:22 +0200446 * we got, 'nr_pages' is how many pages are in the map.
447 */
448 while (page_nr < nr_pages)
449 page_cache_release(pages[page_nr++]);
Fengguang Wuf4e6b492007-10-16 01:24:33 -0700450 in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
Jens Axboeeb207962006-04-27 11:05:22 +0200451
Jens Axboe912d35f2006-04-26 10:59:21 +0200452 if (spd.nr_pages)
Jens Axboe00522fb2006-04-26 14:39:29 +0200453 return splice_to_pipe(pipe, &spd);
Jens Axboe5274f052006-03-30 15:15:30 +0200454
Jens Axboe7480a902006-04-11 13:52:47 +0200455 return error;
Jens Axboe5274f052006-03-30 15:15:30 +0200456}
457
Jens Axboe83f91352006-04-02 23:05:09 +0200458/**
459 * generic_file_splice_read - splice data from file to a pipe
460 * @in: file to splice from
Jens Axboe932cc6d2007-06-21 13:10:21 +0200461 * @ppos: position in @in
Jens Axboe83f91352006-04-02 23:05:09 +0200462 * @pipe: pipe to splice to
463 * @len: number of bytes to splice
464 * @flags: splice modifier flags
465 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200466 * Description:
467 * Will read pages from given file and fill them into a pipe. Can be
468 * used as long as the address_space operations for the source implements
469 * a readpage() hook.
470 *
Jens Axboe83f91352006-04-02 23:05:09 +0200471 */
Jens Axboecbb7e572006-04-11 14:57:50 +0200472ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
473 struct pipe_inode_info *pipe, size_t len,
474 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200475{
476 ssize_t spliced;
477 int ret;
Jens Axboed366d3982007-06-01 14:54:11 +0200478 loff_t isize, left;
479
480 isize = i_size_read(in->f_mapping->host);
481 if (unlikely(*ppos >= isize))
482 return 0;
483
484 left = isize - *ppos;
485 if (unlikely(left < len))
486 len = left;
Jens Axboe5274f052006-03-30 15:15:30 +0200487
488 ret = 0;
489 spliced = 0;
Jens Axboe51a92c02007-07-13 14:11:43 +0200490 while (len && !spliced) {
Jens Axboecbb7e572006-04-11 14:57:50 +0200491 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200492
Jens Axboec4f895c2006-04-19 15:56:12 +0200493 if (ret < 0)
Jens Axboe5274f052006-03-30 15:15:30 +0200494 break;
Jens Axboec4f895c2006-04-19 15:56:12 +0200495 else if (!ret) {
496 if (spliced)
497 break;
498 if (flags & SPLICE_F_NONBLOCK) {
499 ret = -EAGAIN;
500 break;
501 }
502 }
Jens Axboe5274f052006-03-30 15:15:30 +0200503
Jens Axboecbb7e572006-04-11 14:57:50 +0200504 *ppos += ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200505 len -= ret;
506 spliced += ret;
507 }
508
509 if (spliced)
510 return spliced;
511
512 return ret;
513}
514
Jens Axboe059a8f32006-04-02 23:06:05 +0200515EXPORT_SYMBOL(generic_file_splice_read);
516
Jens Axboe5274f052006-03-30 15:15:30 +0200517/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200518 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
Jens Axboe016b6612006-04-25 15:42:00 +0200519 * using sendpage(). Return the number of bytes sent.
Jens Axboe5274f052006-03-30 15:15:30 +0200520 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200521static int pipe_to_sendpage(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +0200522 struct pipe_buffer *buf, struct splice_desc *sd)
523{
Jens Axboe6a14b902007-06-14 13:08:55 +0200524 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200525 loff_t pos = sd->pos;
Jens Axboef84d7512006-05-01 19:59:03 +0200526 int ret, more;
Jens Axboe5274f052006-03-30 15:15:30 +0200527
Jens Axboecac36bb02007-06-14 13:10:48 +0200528 ret = buf->ops->confirm(pipe, buf);
Jens Axboef84d7512006-05-01 19:59:03 +0200529 if (!ret) {
530 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200531
Jens Axboef84d7512006-05-01 19:59:03 +0200532 ret = file->f_op->sendpage(file, buf->page, buf->offset,
533 sd->len, &pos, more);
534 }
Jens Axboe5274f052006-03-30 15:15:30 +0200535
Jens Axboe016b6612006-04-25 15:42:00 +0200536 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200537}
538
539/*
540 * This is a little more tricky than the file -> pipe splicing. There are
541 * basically three cases:
542 *
543 * - Destination page already exists in the address space and there
544 * are users of it. For that case we have no other option that
545 * copying the data. Tough luck.
546 * - Destination page already exists in the address space, but there
547 * are no users of it. Make sure it's uptodate, then drop it. Fall
548 * through to last case.
549 * - Destination page does not exist, we can add the pipe page to
550 * the page cache and avoid the copy.
551 *
Jens Axboe83f91352006-04-02 23:05:09 +0200552 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
553 * sd->flags), we attempt to migrate pages from the pipe to the output
554 * file address space page cache. This is possible if no one else has
555 * the pipe page referenced outside of the pipe and page cache. If
556 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
557 * a new page in the output file page cache and fill/dirty that.
Jens Axboe5274f052006-03-30 15:15:30 +0200558 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200559static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
Jens Axboe5274f052006-03-30 15:15:30 +0200560 struct splice_desc *sd)
561{
Jens Axboe6a14b902007-06-14 13:08:55 +0200562 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200563 struct address_space *mapping = file->f_mapping;
Jens Axboe016b6612006-04-25 15:42:00 +0200564 unsigned int offset, this_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200565 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -0700566 void *fsdata;
Jens Axboe3e7ee3e2006-04-02 23:11:04 +0200567 int ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200568
569 /*
Jens Axboe49d0b212006-04-10 09:04:41 +0200570 * make sure the data in this buffer is uptodate
Jens Axboe5274f052006-03-30 15:15:30 +0200571 */
Jens Axboecac36bb02007-06-14 13:10:48 +0200572 ret = buf->ops->confirm(pipe, buf);
Jens Axboef84d7512006-05-01 19:59:03 +0200573 if (unlikely(ret))
574 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200575
Jens Axboe5274f052006-03-30 15:15:30 +0200576 offset = sd->pos & ~PAGE_CACHE_MASK;
577
Jens Axboe016b6612006-04-25 15:42:00 +0200578 this_len = sd->len;
579 if (this_len + offset > PAGE_CACHE_SIZE)
580 this_len = PAGE_CACHE_SIZE - offset;
581
Nick Pigginafddba42007-10-16 01:25:01 -0700582 ret = pagecache_write_begin(file, mapping, sd->pos, this_len,
583 AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
584 if (unlikely(ret))
585 goto out;
Jens Axboe5274f052006-03-30 15:15:30 +0200586
Jens Axboe0568b402006-05-01 19:50:48 +0200587 if (buf->page != page) {
Jens Axboef84d7512006-05-01 19:59:03 +0200588 /*
589 * Careful, ->map() uses KM_USER0!
590 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200591 char *src = buf->ops->map(pipe, buf, 1);
Jens Axboef84d7512006-05-01 19:59:03 +0200592 char *dst = kmap_atomic(page, KM_USER1);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200593
Jens Axboe016b6612006-04-25 15:42:00 +0200594 memcpy(dst + offset, src + buf->offset, this_len);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200595 flush_dcache_page(page);
Jens Axboef84d7512006-05-01 19:59:03 +0200596 kunmap_atomic(dst, KM_USER1);
Jens Axboe76ad4d12006-05-03 10:41:33 +0200597 buf->ops->unmap(pipe, buf, src);
Jens Axboe5abc97a2006-03-30 15:16:46 +0200598 }
Nick Pigginafddba42007-10-16 01:25:01 -0700599 ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len,
600 page, fsdata);
Jens Axboe5274f052006-03-30 15:15:30 +0200601out:
Jens Axboe5274f052006-03-30 15:15:30 +0200602 return ret;
603}
604
Jens Axboe932cc6d2007-06-21 13:10:21 +0200605/**
606 * __splice_from_pipe - splice data from a pipe to given actor
607 * @pipe: pipe to splice from
608 * @sd: information to @actor
609 * @actor: handler that splices the data
610 *
611 * Description:
612 * This function does little more than loop over the pipe and call
613 * @actor to do the actual moving of a single struct pipe_buffer to
614 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
615 * pipe_to_user.
616 *
Jens Axboe83f91352006-04-02 23:05:09 +0200617 */
Jens Axboec66ab6f2007-06-12 21:17:17 +0200618ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
619 splice_actor *actor)
Jens Axboe5274f052006-03-30 15:15:30 +0200620{
Jens Axboe5274f052006-03-30 15:15:30 +0200621 int ret, do_wakeup, err;
Jens Axboe5274f052006-03-30 15:15:30 +0200622
623 ret = 0;
624 do_wakeup = 0;
625
Jens Axboe5274f052006-03-30 15:15:30 +0200626 for (;;) {
Jens Axboe6f767b02006-04-11 13:53:56 +0200627 if (pipe->nrbufs) {
628 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800629 const struct pipe_buf_operations *ops = buf->ops;
Jens Axboe5274f052006-03-30 15:15:30 +0200630
Jens Axboec66ab6f2007-06-12 21:17:17 +0200631 sd->len = buf->len;
632 if (sd->len > sd->total_len)
633 sd->len = sd->total_len;
Jens Axboe5274f052006-03-30 15:15:30 +0200634
Jens Axboec66ab6f2007-06-12 21:17:17 +0200635 err = actor(pipe, buf, sd);
Jens Axboe016b6612006-04-25 15:42:00 +0200636 if (err <= 0) {
Jens Axboe5274f052006-03-30 15:15:30 +0200637 if (!ret && err != -ENODATA)
638 ret = err;
639
640 break;
641 }
642
Jens Axboe016b6612006-04-25 15:42:00 +0200643 ret += err;
644 buf->offset += err;
645 buf->len -= err;
646
Jens Axboec66ab6f2007-06-12 21:17:17 +0200647 sd->len -= err;
648 sd->pos += err;
649 sd->total_len -= err;
650 if (sd->len)
Jens Axboe016b6612006-04-25 15:42:00 +0200651 continue;
Ingo Molnar73d62d82006-04-11 13:57:21 +0200652
Jens Axboe5274f052006-03-30 15:15:30 +0200653 if (!buf->len) {
654 buf->ops = NULL;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200655 ops->release(pipe, buf);
Jens Axboe6f767b02006-04-11 13:53:56 +0200656 pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
657 pipe->nrbufs--;
658 if (pipe->inode)
659 do_wakeup = 1;
Jens Axboe5274f052006-03-30 15:15:30 +0200660 }
661
Jens Axboec66ab6f2007-06-12 21:17:17 +0200662 if (!sd->total_len)
Jens Axboe5274f052006-03-30 15:15:30 +0200663 break;
664 }
665
Jens Axboe6f767b02006-04-11 13:53:56 +0200666 if (pipe->nrbufs)
Jens Axboe5274f052006-03-30 15:15:30 +0200667 continue;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200668 if (!pipe->writers)
Jens Axboe5274f052006-03-30 15:15:30 +0200669 break;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200670 if (!pipe->waiting_writers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200671 if (ret)
672 break;
673 }
674
Jens Axboec66ab6f2007-06-12 21:17:17 +0200675 if (sd->flags & SPLICE_F_NONBLOCK) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700676 if (!ret)
677 ret = -EAGAIN;
678 break;
679 }
680
Jens Axboe5274f052006-03-30 15:15:30 +0200681 if (signal_pending(current)) {
682 if (!ret)
683 ret = -ERESTARTSYS;
684 break;
685 }
686
687 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200688 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200689 if (waitqueue_active(&pipe->wait))
690 wake_up_interruptible_sync(&pipe->wait);
691 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
Jens Axboe5274f052006-03-30 15:15:30 +0200692 do_wakeup = 0;
693 }
694
Ingo Molnar3a326a22006-04-10 15:18:35 +0200695 pipe_wait(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200696 }
697
Jens Axboe5274f052006-03-30 15:15:30 +0200698 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200699 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200700 if (waitqueue_active(&pipe->wait))
701 wake_up_interruptible(&pipe->wait);
702 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
Jens Axboe5274f052006-03-30 15:15:30 +0200703 }
704
Jens Axboe5274f052006-03-30 15:15:30 +0200705 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200706}
Mark Fasheh40bee44e2007-03-21 13:11:02 +0100707EXPORT_SYMBOL(__splice_from_pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200708
Jens Axboe932cc6d2007-06-21 13:10:21 +0200709/**
710 * splice_from_pipe - splice data from a pipe to a file
711 * @pipe: pipe to splice from
712 * @out: file to splice to
713 * @ppos: position in @out
714 * @len: how many bytes to splice
715 * @flags: splice modifier flags
716 * @actor: handler that splices the data
717 *
718 * Description:
719 * See __splice_from_pipe. This function locks the input and output inodes,
720 * otherwise it's identical to __splice_from_pipe().
721 *
722 */
Mark Fasheh6da61802006-10-17 18:43:07 +0200723ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
724 loff_t *ppos, size_t len, unsigned int flags,
725 splice_actor *actor)
726{
727 ssize_t ret;
728 struct inode *inode = out->f_mapping->host;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200729 struct splice_desc sd = {
730 .total_len = len,
731 .flags = flags,
732 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +0200733 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +0200734 };
Mark Fasheh6da61802006-10-17 18:43:07 +0200735
736 /*
737 * The actor worker might be calling ->prepare_write and
738 * ->commit_write. Most of the time, these expect i_mutex to
739 * be held. Since this may result in an ABBA deadlock with
740 * pipe->inode, we have to order lock acquiry here.
741 */
742 inode_double_lock(inode, pipe->inode);
Jens Axboec66ab6f2007-06-12 21:17:17 +0200743 ret = __splice_from_pipe(pipe, &sd, actor);
Mark Fasheh6da61802006-10-17 18:43:07 +0200744 inode_double_unlock(inode, pipe->inode);
745
746 return ret;
747}
748
749/**
750 * generic_file_splice_write_nolock - generic_file_splice_write without mutexes
751 * @pipe: pipe info
752 * @out: file to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +0200753 * @ppos: position in @out
Mark Fasheh6da61802006-10-17 18:43:07 +0200754 * @len: number of bytes to splice
755 * @flags: splice modifier flags
756 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200757 * Description:
758 * Will either move or copy pages (determined by @flags options) from
759 * the given pipe inode to the given file. The caller is responsible
760 * for acquiring i_mutex on both inodes.
Mark Fasheh6da61802006-10-17 18:43:07 +0200761 *
762 */
763ssize_t
764generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
765 loff_t *ppos, size_t len, unsigned int flags)
766{
767 struct address_space *mapping = out->f_mapping;
768 struct inode *inode = mapping->host;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200769 struct splice_desc sd = {
770 .total_len = len,
771 .flags = flags,
772 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +0200773 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +0200774 };
Mark Fasheh6da61802006-10-17 18:43:07 +0200775 ssize_t ret;
776 int err;
777
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800778 err = remove_suid(out->f_path.dentry);
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200779 if (unlikely(err))
780 return err;
781
Jens Axboec66ab6f2007-06-12 21:17:17 +0200782 ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
Mark Fasheh6da61802006-10-17 18:43:07 +0200783 if (ret > 0) {
Jens Axboe17ee4f42007-06-15 13:10:37 +0200784 unsigned long nr_pages;
785
Mark Fasheh6da61802006-10-17 18:43:07 +0200786 *ppos += ret;
Jens Axboe17ee4f42007-06-15 13:10:37 +0200787 nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Mark Fasheh6da61802006-10-17 18:43:07 +0200788
789 /*
790 * If file or inode is SYNC and we actually wrote some data,
791 * sync it.
792 */
793 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
794 err = generic_osync_inode(inode, mapping,
795 OSYNC_METADATA|OSYNC_DATA);
796
797 if (err)
798 ret = err;
799 }
Jens Axboe17ee4f42007-06-15 13:10:37 +0200800 balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
Mark Fasheh6da61802006-10-17 18:43:07 +0200801 }
802
803 return ret;
804}
805
806EXPORT_SYMBOL(generic_file_splice_write_nolock);
807
Jens Axboe83f91352006-04-02 23:05:09 +0200808/**
809 * generic_file_splice_write - splice data from a pipe to a file
Ingo Molnar3a326a22006-04-10 15:18:35 +0200810 * @pipe: pipe info
Jens Axboe83f91352006-04-02 23:05:09 +0200811 * @out: file to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +0200812 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +0200813 * @len: number of bytes to splice
814 * @flags: splice modifier flags
815 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200816 * Description:
817 * Will either move or copy pages (determined by @flags options) from
818 * the given pipe inode to the given file.
Jens Axboe83f91352006-04-02 23:05:09 +0200819 *
820 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200821ssize_t
822generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +0200823 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200824{
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200825 struct address_space *mapping = out->f_mapping;
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200826 struct inode *inode = mapping->host;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700827 int killsuid, killpriv;
Ingo Molnar3a326a22006-04-10 15:18:35 +0200828 ssize_t ret;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700829 int err = 0;
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200830
Serge E. Hallynb5376772007-10-16 23:31:36 -0700831 killpriv = security_inode_need_killpriv(out->f_path.dentry);
832 killsuid = should_remove_suid(out->f_path.dentry);
833 if (unlikely(killsuid || killpriv)) {
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200834 mutex_lock(&inode->i_mutex);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700835 if (killpriv)
836 err = security_inode_killpriv(out->f_path.dentry);
837 if (!err && killsuid)
838 err = __remove_suid(out->f_path.dentry, killsuid);
Jens Axboe8c34e2d2006-10-17 19:43:22 +0200839 mutex_unlock(&inode->i_mutex);
840 if (err)
841 return err;
842 }
Ingo Molnar3a326a22006-04-10 15:18:35 +0200843
Jens Axboe00522fb2006-04-26 14:39:29 +0200844 ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
Jens Axboea4514eb2006-04-19 15:57:05 +0200845 if (ret > 0) {
Jens Axboe17ee4f42007-06-15 13:10:37 +0200846 unsigned long nr_pages;
847
Jens Axboea4514eb2006-04-19 15:57:05 +0200848 *ppos += ret;
Jens Axboe17ee4f42007-06-15 13:10:37 +0200849 nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200850
Jens Axboea4514eb2006-04-19 15:57:05 +0200851 /*
852 * If file or inode is SYNC and we actually wrote some data,
853 * sync it.
854 */
855 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
Jens Axboea4514eb2006-04-19 15:57:05 +0200856 mutex_lock(&inode->i_mutex);
857 err = generic_osync_inode(inode, mapping,
858 OSYNC_METADATA|OSYNC_DATA);
859 mutex_unlock(&inode->i_mutex);
860
861 if (err)
862 ret = err;
863 }
Jens Axboe17ee4f42007-06-15 13:10:37 +0200864 balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200865 }
866
867 return ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200868}
869
Jens Axboe059a8f32006-04-02 23:06:05 +0200870EXPORT_SYMBOL(generic_file_splice_write);
871
Jens Axboe83f91352006-04-02 23:05:09 +0200872/**
873 * generic_splice_sendpage - splice data from a pipe to a socket
Jens Axboe932cc6d2007-06-21 13:10:21 +0200874 * @pipe: pipe to splice from
Jens Axboe83f91352006-04-02 23:05:09 +0200875 * @out: socket to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +0200876 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +0200877 * @len: number of bytes to splice
878 * @flags: splice modifier flags
879 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200880 * Description:
881 * Will send @len bytes from the pipe to a network socket. No data copying
882 * is involved.
Jens Axboe83f91352006-04-02 23:05:09 +0200883 *
884 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200885ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +0200886 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200887{
Jens Axboe00522fb2006-04-26 14:39:29 +0200888 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
Jens Axboe5274f052006-03-30 15:15:30 +0200889}
890
Jens Axboe059a8f32006-04-02 23:06:05 +0200891EXPORT_SYMBOL(generic_splice_sendpage);
Jeff Garzika0f06782006-03-30 23:06:13 -0500892
Jens Axboe83f91352006-04-02 23:05:09 +0200893/*
894 * Attempt to initiate a splice from pipe to file.
895 */
Ingo Molnar3a326a22006-04-10 15:18:35 +0200896static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +0200897 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200898{
Jens Axboe5274f052006-03-30 15:15:30 +0200899 int ret;
900
Jens Axboe49570e92006-04-11 13:56:09 +0200901 if (unlikely(!out->f_op || !out->f_op->splice_write))
Jens Axboe5274f052006-03-30 15:15:30 +0200902 return -EINVAL;
903
Jens Axboe49570e92006-04-11 13:56:09 +0200904 if (unlikely(!(out->f_mode & FMODE_WRITE)))
Jens Axboe5274f052006-03-30 15:15:30 +0200905 return -EBADF;
906
Jens Axboecbb7e572006-04-11 14:57:50 +0200907 ret = rw_verify_area(WRITE, out, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +0200908 if (unlikely(ret < 0))
909 return ret;
910
Jens Axboecbb7e572006-04-11 14:57:50 +0200911 return out->f_op->splice_write(pipe, out, ppos, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200912}
913
Jens Axboe83f91352006-04-02 23:05:09 +0200914/*
915 * Attempt to initiate a splice from a file to a pipe.
916 */
Jens Axboecbb7e572006-04-11 14:57:50 +0200917static long do_splice_to(struct file *in, loff_t *ppos,
918 struct pipe_inode_info *pipe, size_t len,
919 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200920{
Jens Axboe5274f052006-03-30 15:15:30 +0200921 int ret;
922
Jens Axboe49570e92006-04-11 13:56:09 +0200923 if (unlikely(!in->f_op || !in->f_op->splice_read))
Jens Axboe5274f052006-03-30 15:15:30 +0200924 return -EINVAL;
925
Jens Axboe49570e92006-04-11 13:56:09 +0200926 if (unlikely(!(in->f_mode & FMODE_READ)))
Jens Axboe5274f052006-03-30 15:15:30 +0200927 return -EBADF;
928
Jens Axboecbb7e572006-04-11 14:57:50 +0200929 ret = rw_verify_area(READ, in, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +0200930 if (unlikely(ret < 0))
931 return ret;
932
Jens Axboecbb7e572006-04-11 14:57:50 +0200933 return in->f_op->splice_read(in, ppos, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +0200934}
935
Jens Axboe932cc6d2007-06-21 13:10:21 +0200936/**
937 * splice_direct_to_actor - splices data directly between two non-pipes
938 * @in: file to splice from
939 * @sd: actor information on where to splice to
940 * @actor: handles the data splicing
941 *
942 * Description:
943 * This is a special case helper to splice directly between two
944 * points, without requiring an explicit pipe. Internally an allocated
Randy Dunlap79685b82007-07-27 08:08:51 +0200945 * pipe is cached in the process, and reused during the lifetime of
Jens Axboe932cc6d2007-06-21 13:10:21 +0200946 * that process.
947 *
Jens Axboec66ab6f2007-06-12 21:17:17 +0200948 */
949ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
950 splice_direct_actor *actor)
Jens Axboeb92ce552006-04-11 13:52:07 +0200951{
952 struct pipe_inode_info *pipe;
953 long ret, bytes;
954 umode_t i_mode;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200955 size_t len;
956 int i, flags;
Jens Axboeb92ce552006-04-11 13:52:07 +0200957
958 /*
959 * We require the input being a regular file, as we don't want to
960 * randomly drop data for eg socket -> socket splicing. Use the
961 * piped splicing for that!
962 */
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -0800963 i_mode = in->f_path.dentry->d_inode->i_mode;
Jens Axboeb92ce552006-04-11 13:52:07 +0200964 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
965 return -EINVAL;
966
967 /*
968 * neither in nor out is a pipe, setup an internal pipe attached to
969 * 'out' and transfer the wanted data from 'in' to 'out' through that
970 */
971 pipe = current->splice_pipe;
Jens Axboe49570e92006-04-11 13:56:09 +0200972 if (unlikely(!pipe)) {
Jens Axboeb92ce552006-04-11 13:52:07 +0200973 pipe = alloc_pipe_info(NULL);
974 if (!pipe)
975 return -ENOMEM;
976
977 /*
978 * We don't have an immediate reader, but we'll read the stuff
Jens Axboe00522fb2006-04-26 14:39:29 +0200979 * out of the pipe right after the splice_to_pipe(). So set
Jens Axboeb92ce552006-04-11 13:52:07 +0200980 * PIPE_READERS appropriately.
981 */
982 pipe->readers = 1;
983
984 current->splice_pipe = pipe;
985 }
986
987 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +0200988 * Do the splice.
Jens Axboeb92ce552006-04-11 13:52:07 +0200989 */
990 ret = 0;
991 bytes = 0;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200992 len = sd->total_len;
993 flags = sd->flags;
994
995 /*
996 * Don't block on output, we have to drain the direct pipe.
997 */
998 sd->flags &= ~SPLICE_F_NONBLOCK;
Jens Axboeb92ce552006-04-11 13:52:07 +0200999
1000 while (len) {
Jens Axboe51a92c02007-07-13 14:11:43 +02001001 size_t read_len;
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001002 loff_t pos = sd->pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001003
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001004 ret = do_splice_to(in, &pos, pipe, len, flags);
Jens Axboe51a92c02007-07-13 14:11:43 +02001005 if (unlikely(ret <= 0))
Jens Axboeb92ce552006-04-11 13:52:07 +02001006 goto out_release;
1007
1008 read_len = ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001009 sd->total_len = read_len;
Jens Axboeb92ce552006-04-11 13:52:07 +02001010
1011 /*
1012 * NOTE: nonblocking mode only applies to the input. We
1013 * must not do the output in nonblocking mode as then we
1014 * could get stuck data in the internal pipe:
1015 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001016 ret = actor(pipe, sd);
Jens Axboe51a92c02007-07-13 14:11:43 +02001017 if (unlikely(ret <= 0))
Jens Axboeb92ce552006-04-11 13:52:07 +02001018 goto out_release;
1019
1020 bytes += ret;
1021 len -= ret;
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001022 sd->pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001023
Jens Axboe51a92c02007-07-13 14:11:43 +02001024 if (ret < read_len)
1025 goto out_release;
Jens Axboeb92ce552006-04-11 13:52:07 +02001026 }
1027
1028 pipe->nrbufs = pipe->curbuf = 0;
Jens Axboeb92ce552006-04-11 13:52:07 +02001029 return bytes;
1030
1031out_release:
1032 /*
1033 * If we did an incomplete transfer we must release
1034 * the pipe buffers in question:
1035 */
1036 for (i = 0; i < PIPE_BUFFERS; i++) {
1037 struct pipe_buffer *buf = pipe->bufs + i;
1038
1039 if (buf->ops) {
1040 buf->ops->release(pipe, buf);
1041 buf->ops = NULL;
1042 }
1043 }
1044 pipe->nrbufs = pipe->curbuf = 0;
1045
1046 /*
1047 * If we transferred some data, return the number of bytes:
1048 */
1049 if (bytes > 0)
1050 return bytes;
1051
1052 return ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001053
1054}
1055EXPORT_SYMBOL(splice_direct_to_actor);
1056
1057static int direct_splice_actor(struct pipe_inode_info *pipe,
1058 struct splice_desc *sd)
1059{
Jens Axboe6a14b902007-06-14 13:08:55 +02001060 struct file *file = sd->u.file;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001061
1062 return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);
1063}
1064
Jens Axboe932cc6d2007-06-21 13:10:21 +02001065/**
1066 * do_splice_direct - splices data directly between two files
1067 * @in: file to splice from
1068 * @ppos: input file offset
1069 * @out: file to splice to
1070 * @len: number of bytes to splice
1071 * @flags: splice modifier flags
1072 *
1073 * Description:
1074 * For use by do_sendfile(). splice can easily emulate sendfile, but
1075 * doing it in the application would incur an extra system call
1076 * (splice in + splice out, as compared to just sendfile()). So this helper
1077 * can splice directly through a process-private pipe.
1078 *
1079 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001080long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
1081 size_t len, unsigned int flags)
1082{
1083 struct splice_desc sd = {
1084 .len = len,
1085 .total_len = len,
1086 .flags = flags,
1087 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +02001088 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +02001089 };
Jens Axboe51a92c02007-07-13 14:11:43 +02001090 long ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001091
1092 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
Jens Axboe51a92c02007-07-13 14:11:43 +02001093 if (ret > 0)
1094 *ppos += ret;
1095
Jens Axboec66ab6f2007-06-12 21:17:17 +02001096 return ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001097}
1098
Jens Axboe83f91352006-04-02 23:05:09 +02001099/*
Jens Axboeddac0d32006-11-04 12:49:32 +01001100 * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1101 * location, so checking ->i_pipe is not enough to verify that this is a
1102 * pipe.
1103 */
1104static inline struct pipe_inode_info *pipe_info(struct inode *inode)
1105{
1106 if (S_ISFIFO(inode->i_mode))
1107 return inode->i_pipe;
1108
1109 return NULL;
1110}
1111
1112/*
Jens Axboe83f91352006-04-02 23:05:09 +02001113 * Determine where to splice to/from.
1114 */
Ingo Molnar529565d2006-04-10 15:18:58 +02001115static long do_splice(struct file *in, loff_t __user *off_in,
1116 struct file *out, loff_t __user *off_out,
1117 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001118{
Ingo Molnar3a326a22006-04-10 15:18:35 +02001119 struct pipe_inode_info *pipe;
Jens Axboecbb7e572006-04-11 14:57:50 +02001120 loff_t offset, *off;
Jens Axboea4514eb2006-04-19 15:57:05 +02001121 long ret;
Jens Axboe5274f052006-03-30 15:15:30 +02001122
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001123 pipe = pipe_info(in->f_path.dentry->d_inode);
Ingo Molnar529565d2006-04-10 15:18:58 +02001124 if (pipe) {
1125 if (off_in)
1126 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001127 if (off_out) {
1128 if (out->f_op->llseek == no_llseek)
1129 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001130 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001131 return -EFAULT;
Jens Axboecbb7e572006-04-11 14:57:50 +02001132 off = &offset;
1133 } else
1134 off = &out->f_pos;
Ingo Molnar529565d2006-04-10 15:18:58 +02001135
Jens Axboea4514eb2006-04-19 15:57:05 +02001136 ret = do_splice_from(pipe, out, off, len, flags);
1137
1138 if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
1139 ret = -EFAULT;
1140
1141 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001142 }
Jens Axboe5274f052006-03-30 15:15:30 +02001143
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001144 pipe = pipe_info(out->f_path.dentry->d_inode);
Ingo Molnar529565d2006-04-10 15:18:58 +02001145 if (pipe) {
1146 if (off_out)
1147 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001148 if (off_in) {
1149 if (in->f_op->llseek == no_llseek)
1150 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001151 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001152 return -EFAULT;
Jens Axboecbb7e572006-04-11 14:57:50 +02001153 off = &offset;
1154 } else
1155 off = &in->f_pos;
Ingo Molnar529565d2006-04-10 15:18:58 +02001156
Jens Axboea4514eb2006-04-19 15:57:05 +02001157 ret = do_splice_to(in, off, pipe, len, flags);
1158
1159 if (off_in && copy_to_user(off_in, off, sizeof(loff_t)))
1160 ret = -EFAULT;
1161
1162 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001163 }
Jens Axboe5274f052006-03-30 15:15:30 +02001164
1165 return -EINVAL;
1166}
1167
Jens Axboe912d35f2006-04-26 10:59:21 +02001168/*
Linus Torvalds75723952007-10-01 13:17:28 -07001169 * Do a copy-from-user while holding the mmap_semaphore for reading, in a
1170 * manner safe from deadlocking with simultaneous mmap() (grabbing mmap_sem
1171 * for writing) and page faulting on the user memory pointed to by src.
1172 * This assumes that we will very rarely hit the partial != 0 path, or this
1173 * will not be a win.
1174 */
1175static int copy_from_user_mmap_sem(void *dst, const void __user *src, size_t n)
1176{
1177 int partial;
1178
1179 pagefault_disable();
1180 partial = __copy_from_user_inatomic(dst, src, n);
1181 pagefault_enable();
1182
1183 /*
1184 * Didn't copy everything, drop the mmap_sem and do a faulting copy
1185 */
1186 if (unlikely(partial)) {
1187 up_read(&current->mm->mmap_sem);
1188 partial = copy_from_user(dst, src, n);
1189 down_read(&current->mm->mmap_sem);
1190 }
1191
1192 return partial;
1193}
1194
1195/*
Jens Axboe912d35f2006-04-26 10:59:21 +02001196 * Map an iov into an array of pages and offset/length tupples. With the
1197 * partial_page structure, we can map several non-contiguous ranges into
1198 * our ones pages[] map instead of splitting that operation into pieces.
1199 * Could easily be exported as a generic helper for other users, in which
1200 * case one would probably want to add a 'max_nr_pages' parameter as well.
1201 */
1202static int get_iovec_page_array(const struct iovec __user *iov,
1203 unsigned int nr_vecs, struct page **pages,
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001204 struct partial_page *partial, int aligned)
Jens Axboe912d35f2006-04-26 10:59:21 +02001205{
1206 int buffers = 0, error = 0;
1207
Jens Axboe912d35f2006-04-26 10:59:21 +02001208 down_read(&current->mm->mmap_sem);
1209
1210 while (nr_vecs) {
1211 unsigned long off, npages;
Linus Torvalds75723952007-10-01 13:17:28 -07001212 struct iovec entry;
Jens Axboe912d35f2006-04-26 10:59:21 +02001213 void __user *base;
1214 size_t len;
1215 int i;
1216
Linus Torvalds75723952007-10-01 13:17:28 -07001217 error = -EFAULT;
1218 if (copy_from_user_mmap_sem(&entry, iov, sizeof(entry)))
Jens Axboe912d35f2006-04-26 10:59:21 +02001219 break;
Linus Torvalds75723952007-10-01 13:17:28 -07001220
1221 base = entry.iov_base;
1222 len = entry.iov_len;
Jens Axboe912d35f2006-04-26 10:59:21 +02001223
1224 /*
1225 * Sanity check this iovec. 0 read succeeds.
1226 */
Linus Torvalds75723952007-10-01 13:17:28 -07001227 error = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +02001228 if (unlikely(!len))
1229 break;
1230 error = -EFAULT;
1231 if (unlikely(!base))
1232 break;
1233
1234 /*
1235 * Get this base offset and number of pages, then map
1236 * in the user pages.
1237 */
1238 off = (unsigned long) base & ~PAGE_MASK;
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001239
1240 /*
1241 * If asked for alignment, the offset must be zero and the
1242 * length a multiple of the PAGE_SIZE.
1243 */
1244 error = -EINVAL;
1245 if (aligned && (off || len & ~PAGE_MASK))
1246 break;
1247
Jens Axboe912d35f2006-04-26 10:59:21 +02001248 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1249 if (npages > PIPE_BUFFERS - buffers)
1250 npages = PIPE_BUFFERS - buffers;
1251
1252 error = get_user_pages(current, current->mm,
1253 (unsigned long) base, npages, 0, 0,
1254 &pages[buffers], NULL);
1255
1256 if (unlikely(error <= 0))
1257 break;
1258
1259 /*
1260 * Fill this contiguous range into the partial page map.
1261 */
1262 for (i = 0; i < error; i++) {
Jens Axboe75914892006-05-02 12:57:18 +02001263 const int plen = min_t(size_t, len, PAGE_SIZE - off);
Jens Axboe912d35f2006-04-26 10:59:21 +02001264
1265 partial[buffers].offset = off;
1266 partial[buffers].len = plen;
1267
1268 off = 0;
1269 len -= plen;
1270 buffers++;
1271 }
1272
1273 /*
1274 * We didn't complete this iov, stop here since it probably
1275 * means we have to move some of this into a pipe to
1276 * be able to continue.
1277 */
1278 if (len)
1279 break;
1280
1281 /*
1282 * Don't continue if we mapped fewer pages than we asked for,
1283 * or if we mapped the max number of pages that we have
1284 * room for.
1285 */
1286 if (error < npages || buffers == PIPE_BUFFERS)
1287 break;
1288
1289 nr_vecs--;
1290 iov++;
1291 }
1292
1293 up_read(&current->mm->mmap_sem);
1294
1295 if (buffers)
1296 return buffers;
1297
1298 return error;
1299}
1300
Jens Axboe6a14b902007-06-14 13:08:55 +02001301static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1302 struct splice_desc *sd)
1303{
1304 char *src;
1305 int ret;
1306
Jens Axboecac36bb02007-06-14 13:10:48 +02001307 ret = buf->ops->confirm(pipe, buf);
Jens Axboe6a14b902007-06-14 13:08:55 +02001308 if (unlikely(ret))
1309 return ret;
1310
1311 /*
1312 * See if we can use the atomic maps, by prefaulting in the
1313 * pages and doing an atomic copy
1314 */
1315 if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) {
1316 src = buf->ops->map(pipe, buf, 1);
1317 ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset,
1318 sd->len);
1319 buf->ops->unmap(pipe, buf, src);
1320 if (!ret) {
1321 ret = sd->len;
1322 goto out;
1323 }
1324 }
1325
1326 /*
1327 * No dice, use slow non-atomic map and copy
1328 */
1329 src = buf->ops->map(pipe, buf, 0);
1330
1331 ret = sd->len;
1332 if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len))
1333 ret = -EFAULT;
1334
Jens Axboe6866bef2007-10-16 10:01:29 +02001335 buf->ops->unmap(pipe, buf, src);
Jens Axboe6a14b902007-06-14 13:08:55 +02001336out:
1337 if (ret > 0)
1338 sd->u.userptr += ret;
Jens Axboe6a14b902007-06-14 13:08:55 +02001339 return ret;
1340}
1341
1342/*
1343 * For lack of a better implementation, implement vmsplice() to userspace
1344 * as a simple copy of the pipes pages to the user iov.
1345 */
1346static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
1347 unsigned long nr_segs, unsigned int flags)
1348{
1349 struct pipe_inode_info *pipe;
1350 struct splice_desc sd;
1351 ssize_t size;
1352 int error;
1353 long ret;
1354
1355 pipe = pipe_info(file->f_path.dentry->d_inode);
1356 if (!pipe)
1357 return -EBADF;
1358
1359 if (pipe->inode)
1360 mutex_lock(&pipe->inode->i_mutex);
1361
1362 error = ret = 0;
1363 while (nr_segs) {
1364 void __user *base;
1365 size_t len;
1366
1367 /*
1368 * Get user address base and length for this iovec.
1369 */
1370 error = get_user(base, &iov->iov_base);
1371 if (unlikely(error))
1372 break;
1373 error = get_user(len, &iov->iov_len);
1374 if (unlikely(error))
1375 break;
1376
1377 /*
1378 * Sanity check this iovec. 0 read succeeds.
1379 */
1380 if (unlikely(!len))
1381 break;
1382 if (unlikely(!base)) {
1383 error = -EFAULT;
1384 break;
1385 }
1386
1387 sd.len = 0;
1388 sd.total_len = len;
1389 sd.flags = flags;
1390 sd.u.userptr = base;
1391 sd.pos = 0;
1392
1393 size = __splice_from_pipe(pipe, &sd, pipe_to_user);
1394 if (size < 0) {
1395 if (!ret)
1396 ret = size;
1397
1398 break;
1399 }
1400
1401 ret += size;
1402
1403 if (size < len)
1404 break;
1405
1406 nr_segs--;
1407 iov++;
1408 }
1409
1410 if (pipe->inode)
1411 mutex_unlock(&pipe->inode->i_mutex);
1412
1413 if (!ret)
1414 ret = error;
1415
1416 return ret;
1417}
1418
Jens Axboe912d35f2006-04-26 10:59:21 +02001419/*
1420 * vmsplice splices a user address range into a pipe. It can be thought of
1421 * as splice-from-memory, where the regular splice is splice-from-file (or
1422 * to file). In both cases the output is a pipe, naturally.
Jens Axboe912d35f2006-04-26 10:59:21 +02001423 */
Jens Axboe6a14b902007-06-14 13:08:55 +02001424static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
1425 unsigned long nr_segs, unsigned int flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001426{
Jens Axboeddac0d32006-11-04 12:49:32 +01001427 struct pipe_inode_info *pipe;
Jens Axboe912d35f2006-04-26 10:59:21 +02001428 struct page *pages[PIPE_BUFFERS];
1429 struct partial_page partial[PIPE_BUFFERS];
1430 struct splice_pipe_desc spd = {
1431 .pages = pages,
1432 .partial = partial,
1433 .flags = flags,
1434 .ops = &user_page_pipe_buf_ops,
1435 };
1436
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001437 pipe = pipe_info(file->f_path.dentry->d_inode);
Jens Axboeddac0d32006-11-04 12:49:32 +01001438 if (!pipe)
Jens Axboe912d35f2006-04-26 10:59:21 +02001439 return -EBADF;
Jens Axboe912d35f2006-04-26 10:59:21 +02001440
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001441 spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
1442 flags & SPLICE_F_GIFT);
Jens Axboe912d35f2006-04-26 10:59:21 +02001443 if (spd.nr_pages <= 0)
1444 return spd.nr_pages;
1445
Jens Axboe00522fb2006-04-26 14:39:29 +02001446 return splice_to_pipe(pipe, &spd);
Jens Axboe912d35f2006-04-26 10:59:21 +02001447}
1448
Jens Axboe6a14b902007-06-14 13:08:55 +02001449/*
1450 * Note that vmsplice only really supports true splicing _from_ user memory
1451 * to a pipe, not the other way around. Splicing from user memory is a simple
1452 * operation that can be supported without any funky alignment restrictions
1453 * or nasty vm tricks. We simply map in the user memory and fill them into
1454 * a pipe. The reverse isn't quite as easy, though. There are two possible
1455 * solutions for that:
1456 *
1457 * - memcpy() the data internally, at which point we might as well just
1458 * do a regular read() on the buffer anyway.
1459 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1460 * has restriction limitations on both ends of the pipe).
1461 *
1462 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1463 *
1464 */
Jens Axboe912d35f2006-04-26 10:59:21 +02001465asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
1466 unsigned long nr_segs, unsigned int flags)
1467{
1468 struct file *file;
1469 long error;
1470 int fput;
1471
Jens Axboe6a14b902007-06-14 13:08:55 +02001472 if (unlikely(nr_segs > UIO_MAXIOV))
1473 return -EINVAL;
1474 else if (unlikely(!nr_segs))
1475 return 0;
1476
Jens Axboe912d35f2006-04-26 10:59:21 +02001477 error = -EBADF;
1478 file = fget_light(fd, &fput);
1479 if (file) {
1480 if (file->f_mode & FMODE_WRITE)
Jens Axboe6a14b902007-06-14 13:08:55 +02001481 error = vmsplice_to_pipe(file, iov, nr_segs, flags);
1482 else if (file->f_mode & FMODE_READ)
1483 error = vmsplice_to_user(file, iov, nr_segs, flags);
Jens Axboe912d35f2006-04-26 10:59:21 +02001484
1485 fput_light(file, fput);
1486 }
1487
1488 return error;
1489}
1490
Ingo Molnar529565d2006-04-10 15:18:58 +02001491asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
1492 int fd_out, loff_t __user *off_out,
1493 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001494{
1495 long error;
1496 struct file *in, *out;
1497 int fput_in, fput_out;
1498
1499 if (unlikely(!len))
1500 return 0;
1501
1502 error = -EBADF;
Ingo Molnar529565d2006-04-10 15:18:58 +02001503 in = fget_light(fd_in, &fput_in);
Jens Axboe5274f052006-03-30 15:15:30 +02001504 if (in) {
1505 if (in->f_mode & FMODE_READ) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001506 out = fget_light(fd_out, &fput_out);
Jens Axboe5274f052006-03-30 15:15:30 +02001507 if (out) {
1508 if (out->f_mode & FMODE_WRITE)
Ingo Molnar529565d2006-04-10 15:18:58 +02001509 error = do_splice(in, off_in,
1510 out, off_out,
1511 len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001512 fput_light(out, fput_out);
1513 }
1514 }
1515
1516 fput_light(in, fput_in);
1517 }
1518
1519 return error;
1520}
Jens Axboe70524492006-04-11 15:51:17 +02001521
1522/*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001523 * Make sure there's data to read. Wait for input if we can, otherwise
1524 * return an appropriate error.
1525 */
1526static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1527{
1528 int ret;
1529
1530 /*
1531 * Check ->nrbufs without the inode lock first. This function
1532 * is speculative anyways, so missing one is ok.
1533 */
1534 if (pipe->nrbufs)
1535 return 0;
1536
1537 ret = 0;
1538 mutex_lock(&pipe->inode->i_mutex);
1539
1540 while (!pipe->nrbufs) {
1541 if (signal_pending(current)) {
1542 ret = -ERESTARTSYS;
1543 break;
1544 }
1545 if (!pipe->writers)
1546 break;
1547 if (!pipe->waiting_writers) {
1548 if (flags & SPLICE_F_NONBLOCK) {
1549 ret = -EAGAIN;
1550 break;
1551 }
1552 }
1553 pipe_wait(pipe);
1554 }
1555
1556 mutex_unlock(&pipe->inode->i_mutex);
1557 return ret;
1558}
1559
1560/*
1561 * Make sure there's writeable room. Wait for room if we can, otherwise
1562 * return an appropriate error.
1563 */
1564static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
1565{
1566 int ret;
1567
1568 /*
1569 * Check ->nrbufs without the inode lock first. This function
1570 * is speculative anyways, so missing one is ok.
1571 */
1572 if (pipe->nrbufs < PIPE_BUFFERS)
1573 return 0;
1574
1575 ret = 0;
1576 mutex_lock(&pipe->inode->i_mutex);
1577
1578 while (pipe->nrbufs >= PIPE_BUFFERS) {
1579 if (!pipe->readers) {
1580 send_sig(SIGPIPE, current, 0);
1581 ret = -EPIPE;
1582 break;
1583 }
1584 if (flags & SPLICE_F_NONBLOCK) {
1585 ret = -EAGAIN;
1586 break;
1587 }
1588 if (signal_pending(current)) {
1589 ret = -ERESTARTSYS;
1590 break;
1591 }
1592 pipe->waiting_writers++;
1593 pipe_wait(pipe);
1594 pipe->waiting_writers--;
1595 }
1596
1597 mutex_unlock(&pipe->inode->i_mutex);
1598 return ret;
1599}
1600
1601/*
Jens Axboe70524492006-04-11 15:51:17 +02001602 * Link contents of ipipe to opipe.
1603 */
1604static int link_pipe(struct pipe_inode_info *ipipe,
1605 struct pipe_inode_info *opipe,
1606 size_t len, unsigned int flags)
1607{
1608 struct pipe_buffer *ibuf, *obuf;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001609 int ret = 0, i = 0, nbuf;
Jens Axboe70524492006-04-11 15:51:17 +02001610
1611 /*
1612 * Potential ABBA deadlock, work around it by ordering lock
1613 * grabbing by inode address. Otherwise two different processes
1614 * could deadlock (one doing tee from A -> B, the other from B -> A).
1615 */
Mark Fasheh62752ee2006-10-17 10:31:38 +02001616 inode_double_lock(ipipe->inode, opipe->inode);
Jens Axboe70524492006-04-11 15:51:17 +02001617
Jens Axboeaadd06e2006-07-10 11:00:01 +02001618 do {
Jens Axboe70524492006-04-11 15:51:17 +02001619 if (!opipe->readers) {
1620 send_sig(SIGPIPE, current, 0);
1621 if (!ret)
1622 ret = -EPIPE;
1623 break;
1624 }
Jens Axboe70524492006-04-11 15:51:17 +02001625
1626 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001627 * If we have iterated all input buffers or ran out of
1628 * output room, break.
Jens Axboe70524492006-04-11 15:51:17 +02001629 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001630 if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS)
Jens Axboe70524492006-04-11 15:51:17 +02001631 break;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001632
1633 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
1634 nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
1635
Jens Axboe2a27250e2006-04-19 15:56:40 +02001636 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001637 * Get a reference to this pipe buffer,
1638 * so we can copy the contents over.
Jens Axboe2a27250e2006-04-19 15:56:40 +02001639 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001640 ibuf->ops->get(ipipe, ibuf);
Jens Axboe70524492006-04-11 15:51:17 +02001641
Jens Axboeaadd06e2006-07-10 11:00:01 +02001642 obuf = opipe->bufs + nbuf;
1643 *obuf = *ibuf;
Jens Axboe70524492006-04-11 15:51:17 +02001644
Jens Axboeaadd06e2006-07-10 11:00:01 +02001645 /*
1646 * Don't inherit the gift flag, we need to
1647 * prevent multiple steals of this page.
1648 */
1649 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1650
1651 if (obuf->len > len)
1652 obuf->len = len;
1653
1654 opipe->nrbufs++;
1655 ret += obuf->len;
1656 len -= obuf->len;
1657 i++;
1658 } while (len);
Jens Axboe70524492006-04-11 15:51:17 +02001659
Mark Fasheh62752ee2006-10-17 10:31:38 +02001660 inode_double_unlock(ipipe->inode, opipe->inode);
Jens Axboe70524492006-04-11 15:51:17 +02001661
Jens Axboeaadd06e2006-07-10 11:00:01 +02001662 /*
1663 * If we put data in the output pipe, wakeup any potential readers.
1664 */
1665 if (ret > 0) {
Jens Axboe70524492006-04-11 15:51:17 +02001666 smp_mb();
1667 if (waitqueue_active(&opipe->wait))
1668 wake_up_interruptible(&opipe->wait);
1669 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1670 }
1671
1672 return ret;
1673}
1674
1675/*
1676 * This is a tee(1) implementation that works on pipes. It doesn't copy
1677 * any data, it simply references the 'in' pages on the 'out' pipe.
1678 * The 'flags' used are the SPLICE_F_* variants, currently the only
1679 * applicable one is SPLICE_F_NONBLOCK.
1680 */
1681static long do_tee(struct file *in, struct file *out, size_t len,
1682 unsigned int flags)
1683{
Josef "Jeff" Sipek0f7fc9e2006-12-08 02:36:35 -08001684 struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode);
1685 struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001686 int ret = -EINVAL;
Jens Axboe70524492006-04-11 15:51:17 +02001687
1688 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001689 * Duplicate the contents of ipipe to opipe without actually
1690 * copying the data.
Jens Axboe70524492006-04-11 15:51:17 +02001691 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001692 if (ipipe && opipe && ipipe != opipe) {
1693 /*
1694 * Keep going, unless we encounter an error. The ipipe/opipe
1695 * ordering doesn't really matter.
1696 */
1697 ret = link_ipipe_prep(ipipe, flags);
1698 if (!ret) {
1699 ret = link_opipe_prep(opipe, flags);
1700 if (!ret) {
1701 ret = link_pipe(ipipe, opipe, len, flags);
1702 if (!ret && (flags & SPLICE_F_NONBLOCK))
1703 ret = -EAGAIN;
1704 }
1705 }
1706 }
Jens Axboe70524492006-04-11 15:51:17 +02001707
Jens Axboeaadd06e2006-07-10 11:00:01 +02001708 return ret;
Jens Axboe70524492006-04-11 15:51:17 +02001709}
1710
1711asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
1712{
1713 struct file *in;
1714 int error, fput_in;
1715
1716 if (unlikely(!len))
1717 return 0;
1718
1719 error = -EBADF;
1720 in = fget_light(fdin, &fput_in);
1721 if (in) {
1722 if (in->f_mode & FMODE_READ) {
1723 int fput_out;
1724 struct file *out = fget_light(fdout, &fput_out);
1725
1726 if (out) {
1727 if (out->f_mode & FMODE_WRITE)
1728 error = do_tee(in, out, len, flags);
1729 fput_light(out, fput_out);
1730 }
1731 }
1732 fput_light(in, fput_in);
1733 }
1734
1735 return error;
1736}