blob: 476024bb6546527887517868b122c9305dc32d07 [file] [log] [blame]
Jens Axboe5274f052006-03-30 15:15:30 +02001/*
2 * "splice": joining two ropes together by interweaving their strands.
3 *
4 * This is the "extended pipe" functionality, where a pipe is used as
5 * an arbitrary in-memory buffer. Think of a pipe as a small kernel
6 * buffer that you can use to transfer data from one end to the other.
7 *
8 * The traditional unix read/write is extended with a "splice()" operation
9 * that transfers data buffers to or from a pipe buffer.
10 *
11 * Named by Larry McVoy, original implementation from Linus, extended by
Jens Axboec2058e02006-04-11 13:56:34 +020012 * Jens to support splicing to files, network, direct splicing, etc and
13 * fixing lots of bugs.
Jens Axboe5274f052006-03-30 15:15:30 +020014 *
Jens Axboe0fe23472006-09-04 15:41:16 +020015 * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
Jens Axboec2058e02006-04-11 13:56:34 +020016 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
17 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
Jens Axboe5274f052006-03-30 15:15:30 +020018 *
19 */
20#include <linux/fs.h>
21#include <linux/file.h>
22#include <linux/pagemap.h>
Jens Axboed6b29d72007-06-04 09:59:47 +020023#include <linux/splice.h>
KAMEZAWA Hiroyuki08e552c2009-01-07 18:08:01 -080024#include <linux/memcontrol.h>
Jens Axboe5274f052006-03-30 15:15:30 +020025#include <linux/mm_inline.h>
Jens Axboe5abc97a2006-03-30 15:16:46 +020026#include <linux/swap.h>
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020027#include <linux/writeback.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -050028#include <linux/export.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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090032#include <linux/gfp.h>
Eric Dumazet35f9c092012-04-05 03:05:35 +000033#include <linux/socket.h>
Al Viro76b021d2013-03-02 10:19:56 -050034#include <linux/compat.h>
Al Viro06ae43f2013-03-20 13:19:30 -040035#include "internal.h"
Jens Axboe5274f052006-03-30 15:15:30 +020036
Jens Axboe83f91352006-04-02 23:05:09 +020037/*
38 * Attempt to steal a page from a pipe buffer. This should perhaps go into
39 * a vm helper function, it's already simplified quite a bit by the
40 * addition of remove_mapping(). If success is returned, the caller may
41 * attempt to reuse this page for another destination.
42 */
Jens Axboe76ad4d12006-05-03 10:41:33 +020043static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
Jens Axboe5abc97a2006-03-30 15:16:46 +020044 struct pipe_buffer *buf)
45{
46 struct page *page = buf->page;
Jens Axboe9e94cd42006-06-20 15:01:12 +020047 struct address_space *mapping;
Jens Axboe5abc97a2006-03-30 15:16:46 +020048
Jens Axboe9e0267c2006-04-19 15:57:31 +020049 lock_page(page);
50
Jens Axboe9e94cd42006-06-20 15:01:12 +020051 mapping = page_mapping(page);
52 if (mapping) {
53 WARN_ON(!PageUptodate(page));
Jens Axboe5abc97a2006-03-30 15:16:46 +020054
Jens Axboe9e94cd42006-06-20 15:01:12 +020055 /*
56 * At least for ext2 with nobh option, we need to wait on
57 * writeback completing on this page, since we'll remove it
58 * from the pagecache. Otherwise truncate wont wait on the
59 * page, allowing the disk blocks to be reused by someone else
60 * before we actually wrote our data to them. fs corruption
61 * ensues.
62 */
63 wait_on_page_writeback(page);
Jens Axboead8d6f02006-04-02 23:10:32 +020064
David Howells266cf652009-04-03 16:42:36 +010065 if (page_has_private(page) &&
66 !try_to_release_page(page, GFP_KERNEL))
Jens Axboeca39d652008-05-20 21:27:41 +020067 goto out_unlock;
Jens Axboe4f6f0bd2006-04-02 23:04:46 +020068
Jens Axboe9e94cd42006-06-20 15:01:12 +020069 /*
70 * If we succeeded in removing the mapping, set LRU flag
71 * and return good.
72 */
73 if (remove_mapping(mapping, page)) {
74 buf->flags |= PIPE_BUF_FLAG_LRU;
75 return 0;
76 }
Jens Axboe9e0267c2006-04-19 15:57:31 +020077 }
Jens Axboe5abc97a2006-03-30 15:16:46 +020078
Jens Axboe9e94cd42006-06-20 15:01:12 +020079 /*
80 * Raced with truncate or failed to remove page from current
81 * address space, unlock and return failure.
82 */
Jens Axboeca39d652008-05-20 21:27:41 +020083out_unlock:
Jens Axboe9e94cd42006-06-20 15:01:12 +020084 unlock_page(page);
85 return 1;
Jens Axboe5abc97a2006-03-30 15:16:46 +020086}
87
Jens Axboe76ad4d12006-05-03 10:41:33 +020088static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +020089 struct pipe_buffer *buf)
90{
91 page_cache_release(buf->page);
Jens Axboe14328732006-05-03 10:35:26 +020092 buf->flags &= ~PIPE_BUF_FLAG_LRU;
Jens Axboe5274f052006-03-30 15:15:30 +020093}
94
Jens Axboe08457182007-06-12 20:51:32 +020095/*
96 * Check whether the contents of buf is OK to access. Since the content
97 * is a page cache page, IO may be in flight.
98 */
Jens Axboecac36bb02007-06-14 13:10:48 +020099static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
100 struct pipe_buffer *buf)
Jens Axboe5274f052006-03-30 15:15:30 +0200101{
102 struct page *page = buf->page;
Jens Axboe49d0b212006-04-10 09:04:41 +0200103 int err;
Jens Axboe5274f052006-03-30 15:15:30 +0200104
105 if (!PageUptodate(page)) {
Jens Axboe49d0b212006-04-10 09:04:41 +0200106 lock_page(page);
107
108 /*
109 * Page got truncated/unhashed. This will cause a 0-byte
Ingo Molnar73d62d82006-04-11 13:57:21 +0200110 * splice, if this is the first page.
Jens Axboe49d0b212006-04-10 09:04:41 +0200111 */
112 if (!page->mapping) {
113 err = -ENODATA;
114 goto error;
115 }
116
117 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +0200118 * Uh oh, read-error from disk.
Jens Axboe49d0b212006-04-10 09:04:41 +0200119 */
120 if (!PageUptodate(page)) {
121 err = -EIO;
122 goto error;
123 }
124
125 /*
Jens Axboef84d7512006-05-01 19:59:03 +0200126 * Page is ok afterall, we are done.
Jens Axboe49d0b212006-04-10 09:04:41 +0200127 */
Jens Axboe5274f052006-03-30 15:15:30 +0200128 unlock_page(page);
Jens Axboe5274f052006-03-30 15:15:30 +0200129 }
130
Jens Axboef84d7512006-05-01 19:59:03 +0200131 return 0;
Jens Axboe49d0b212006-04-10 09:04:41 +0200132error:
133 unlock_page(page);
Jens Axboef84d7512006-05-01 19:59:03 +0200134 return err;
Jens Axboe70524492006-04-11 15:51:17 +0200135}
136
Hugh Dickins708e3502011-07-25 17:12:32 -0700137const struct pipe_buf_operations page_cache_pipe_buf_ops = {
Jens Axboe5274f052006-03-30 15:15:30 +0200138 .can_merge = 0,
Jens Axboecac36bb02007-06-14 13:10:48 +0200139 .confirm = page_cache_pipe_buf_confirm,
Jens Axboe5274f052006-03-30 15:15:30 +0200140 .release = page_cache_pipe_buf_release,
Jens Axboe5abc97a2006-03-30 15:16:46 +0200141 .steal = page_cache_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200142 .get = generic_pipe_buf_get,
Jens Axboe5274f052006-03-30 15:15:30 +0200143};
144
Jens Axboe912d35f2006-04-26 10:59:21 +0200145static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
146 struct pipe_buffer *buf)
147{
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200148 if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
149 return 1;
150
Jens Axboe14328732006-05-03 10:35:26 +0200151 buf->flags |= PIPE_BUF_FLAG_LRU;
Jens Axboe330ab712006-05-02 15:29:57 +0200152 return generic_pipe_buf_steal(pipe, buf);
Jens Axboe912d35f2006-04-26 10:59:21 +0200153}
154
Eric Dumazetd4c3cca2006-12-13 00:34:04 -0800155static const struct pipe_buf_operations user_page_pipe_buf_ops = {
Jens Axboe912d35f2006-04-26 10:59:21 +0200156 .can_merge = 0,
Jens Axboecac36bb02007-06-14 13:10:48 +0200157 .confirm = generic_pipe_buf_confirm,
Jens Axboe912d35f2006-04-26 10:59:21 +0200158 .release = page_cache_pipe_buf_release,
159 .steal = user_page_pipe_buf_steal,
Jens Axboef84d7512006-05-01 19:59:03 +0200160 .get = generic_pipe_buf_get,
Jens Axboe912d35f2006-04-26 10:59:21 +0200161};
162
Namhyung Kim825cdcb2011-05-23 19:58:53 +0200163static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
164{
165 smp_mb();
166 if (waitqueue_active(&pipe->wait))
167 wake_up_interruptible(&pipe->wait);
168 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
169}
170
Jens Axboe932cc6d2007-06-21 13:10:21 +0200171/**
172 * splice_to_pipe - fill passed data into a pipe
173 * @pipe: pipe to fill
174 * @spd: data to fill
175 *
176 * Description:
Randy Dunlap79685b82007-07-27 08:08:51 +0200177 * @spd contains a map of pages and len/offset tuples, along with
Jens Axboe932cc6d2007-06-21 13:10:21 +0200178 * the struct pipe_buf_operations associated with these pages. This
179 * function will link that data to the pipe.
180 *
Jens Axboe83f91352006-04-02 23:05:09 +0200181 */
Jens Axboed6b29d72007-06-04 09:59:47 +0200182ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
183 struct splice_pipe_desc *spd)
Jens Axboe5274f052006-03-30 15:15:30 +0200184{
Jens Axboe00de00b2007-06-15 13:14:22 +0200185 unsigned int spd_pages = spd->nr_pages;
Jens Axboe912d35f2006-04-26 10:59:21 +0200186 int ret, do_wakeup, page_nr;
Jens Axboe5274f052006-03-30 15:15:30 +0200187
188 ret = 0;
189 do_wakeup = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +0200190 page_nr = 0;
Jens Axboe5274f052006-03-30 15:15:30 +0200191
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200192 pipe_lock(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200193
Jens Axboe5274f052006-03-30 15:15:30 +0200194 for (;;) {
Ingo Molnar3a326a22006-04-10 15:18:35 +0200195 if (!pipe->readers) {
Jens Axboe5274f052006-03-30 15:15:30 +0200196 send_sig(SIGPIPE, current, 0);
197 if (!ret)
198 ret = -EPIPE;
199 break;
200 }
201
Jens Axboe35f3d142010-05-20 10:43:18 +0200202 if (pipe->nrbufs < pipe->buffers) {
203 int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
Ingo Molnar3a326a22006-04-10 15:18:35 +0200204 struct pipe_buffer *buf = pipe->bufs + newbuf;
Jens Axboe5274f052006-03-30 15:15:30 +0200205
Jens Axboe912d35f2006-04-26 10:59:21 +0200206 buf->page = spd->pages[page_nr];
207 buf->offset = spd->partial[page_nr].offset;
208 buf->len = spd->partial[page_nr].len;
Jens Axboe497f9622007-06-11 12:00:45 +0200209 buf->private = spd->partial[page_nr].private;
Jens Axboe912d35f2006-04-26 10:59:21 +0200210 buf->ops = spd->ops;
Jens Axboe7afa6fd2006-05-01 20:02:33 +0200211 if (spd->flags & SPLICE_F_GIFT)
212 buf->flags |= PIPE_BUF_FLAG_GIFT;
213
Jens Axboe6f767b02006-04-11 13:53:56 +0200214 pipe->nrbufs++;
Jens Axboe912d35f2006-04-26 10:59:21 +0200215 page_nr++;
216 ret += buf->len;
217
Al Viro6447a3c2013-03-21 11:01:38 -0400218 if (pipe->files)
Jens Axboe6f767b02006-04-11 13:53:56 +0200219 do_wakeup = 1;
Jens Axboe5274f052006-03-30 15:15:30 +0200220
Jens Axboe912d35f2006-04-26 10:59:21 +0200221 if (!--spd->nr_pages)
Jens Axboe5274f052006-03-30 15:15:30 +0200222 break;
Jens Axboe35f3d142010-05-20 10:43:18 +0200223 if (pipe->nrbufs < pipe->buffers)
Jens Axboe5274f052006-03-30 15:15:30 +0200224 continue;
225
226 break;
227 }
228
Jens Axboe912d35f2006-04-26 10:59:21 +0200229 if (spd->flags & SPLICE_F_NONBLOCK) {
Linus Torvalds29e35092006-04-02 12:46:35 -0700230 if (!ret)
231 ret = -EAGAIN;
232 break;
233 }
234
Jens Axboe5274f052006-03-30 15:15:30 +0200235 if (signal_pending(current)) {
236 if (!ret)
237 ret = -ERESTARTSYS;
238 break;
239 }
240
241 if (do_wakeup) {
Jens Axboec0bd1f62006-04-10 09:03:32 +0200242 smp_mb();
Ingo Molnar3a326a22006-04-10 15:18:35 +0200243 if (waitqueue_active(&pipe->wait))
244 wake_up_interruptible_sync(&pipe->wait);
245 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
Jens Axboe5274f052006-03-30 15:15:30 +0200246 do_wakeup = 0;
247 }
248
Ingo Molnar3a326a22006-04-10 15:18:35 +0200249 pipe->waiting_writers++;
250 pipe_wait(pipe);
251 pipe->waiting_writers--;
Jens Axboe5274f052006-03-30 15:15:30 +0200252 }
253
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200254 pipe_unlock(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200255
Namhyung Kim825cdcb2011-05-23 19:58:53 +0200256 if (do_wakeup)
257 wakeup_pipe_readers(pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200258
Jens Axboe00de00b2007-06-15 13:14:22 +0200259 while (page_nr < spd_pages)
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800260 spd->spd_release(spd, page_nr++);
Jens Axboe5274f052006-03-30 15:15:30 +0200261
262 return ret;
263}
264
Hugh Dickins708e3502011-07-25 17:12:32 -0700265void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800266{
267 page_cache_release(spd->pages[i]);
268}
269
Jens Axboe35f3d142010-05-20 10:43:18 +0200270/*
271 * Check if we need to grow the arrays holding pages and partial page
272 * descriptions.
273 */
Eric Dumazet047fe362012-06-12 15:24:40 +0200274int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
Jens Axboe35f3d142010-05-20 10:43:18 +0200275{
Eric Dumazet047fe362012-06-12 15:24:40 +0200276 unsigned int buffers = ACCESS_ONCE(pipe->buffers);
277
278 spd->nr_pages_max = buffers;
279 if (buffers <= PIPE_DEF_BUFFERS)
Jens Axboe35f3d142010-05-20 10:43:18 +0200280 return 0;
281
Eric Dumazet047fe362012-06-12 15:24:40 +0200282 spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
283 spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
Jens Axboe35f3d142010-05-20 10:43:18 +0200284
285 if (spd->pages && spd->partial)
286 return 0;
287
288 kfree(spd->pages);
289 kfree(spd->partial);
290 return -ENOMEM;
291}
292
Eric Dumazet047fe362012-06-12 15:24:40 +0200293void splice_shrink_spd(struct splice_pipe_desc *spd)
Jens Axboe35f3d142010-05-20 10:43:18 +0200294{
Eric Dumazet047fe362012-06-12 15:24:40 +0200295 if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
Jens Axboe35f3d142010-05-20 10:43:18 +0200296 return;
297
298 kfree(spd->pages);
299 kfree(spd->partial);
300}
301
Ingo Molnar3a326a22006-04-10 15:18:35 +0200302static int
Jens Axboecbb7e572006-04-11 14:57:50 +0200303__generic_file_splice_read(struct file *in, loff_t *ppos,
304 struct pipe_inode_info *pipe, size_t len,
305 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200306{
307 struct address_space *mapping = in->f_mapping;
Fengguang Wud8983912007-07-19 01:48:06 -0700308 unsigned int loff, nr_pages, req_pages;
Jens Axboe35f3d142010-05-20 10:43:18 +0200309 struct page *pages[PIPE_DEF_BUFFERS];
310 struct partial_page partial[PIPE_DEF_BUFFERS];
Jens Axboe5274f052006-03-30 15:15:30 +0200311 struct page *page;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200312 pgoff_t index, end_index;
313 loff_t isize;
Jens Axboeeb207962006-04-27 11:05:22 +0200314 int error, page_nr;
Jens Axboe912d35f2006-04-26 10:59:21 +0200315 struct splice_pipe_desc spd = {
316 .pages = pages,
317 .partial = partial,
Eric Dumazet047fe362012-06-12 15:24:40 +0200318 .nr_pages_max = PIPE_DEF_BUFFERS,
Jens Axboe912d35f2006-04-26 10:59:21 +0200319 .flags = flags,
320 .ops = &page_cache_pipe_buf_ops,
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800321 .spd_release = spd_release_page,
Jens Axboe912d35f2006-04-26 10:59:21 +0200322 };
Jens Axboe5274f052006-03-30 15:15:30 +0200323
Jens Axboe35f3d142010-05-20 10:43:18 +0200324 if (splice_grow_spd(pipe, &spd))
325 return -ENOMEM;
326
Jens Axboecbb7e572006-04-11 14:57:50 +0200327 index = *ppos >> PAGE_CACHE_SHIFT;
Jens Axboe912d35f2006-04-26 10:59:21 +0200328 loff = *ppos & ~PAGE_CACHE_MASK;
Fengguang Wud8983912007-07-19 01:48:06 -0700329 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Eric Dumazet047fe362012-06-12 15:24:40 +0200330 nr_pages = min(req_pages, spd.nr_pages_max);
Jens Axboe5274f052006-03-30 15:15:30 +0200331
332 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200333 * Lookup the (hopefully) full range of pages we need.
334 */
Jens Axboe35f3d142010-05-20 10:43:18 +0200335 spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages);
Fengguang Wu431a4822007-07-19 01:48:05 -0700336 index += spd.nr_pages;
Jens Axboeeb207962006-04-27 11:05:22 +0200337
338 /*
339 * If find_get_pages_contig() returned fewer pages than we needed,
Fengguang Wu431a4822007-07-19 01:48:05 -0700340 * readahead/allocate the rest and fill in the holes.
Jens Axboeeb207962006-04-27 11:05:22 +0200341 */
Fengguang Wu431a4822007-07-19 01:48:05 -0700342 if (spd.nr_pages < nr_pages)
Rusty Russellcf914a72007-07-19 01:48:08 -0700343 page_cache_sync_readahead(mapping, &in->f_ra, in,
344 index, req_pages - spd.nr_pages);
Fengguang Wu431a4822007-07-19 01:48:05 -0700345
Jens Axboe932cc6d2007-06-21 13:10:21 +0200346 error = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200347 while (spd.nr_pages < nr_pages) {
348 /*
349 * Page could be there, find_get_pages_contig() breaks on
350 * the first hole.
351 */
352 page = find_get_page(mapping, index);
353 if (!page) {
Jens Axboee27dedd2006-05-01 19:59:54 +0200354 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200355 * page didn't exist, allocate one.
356 */
357 page = page_cache_alloc_cold(mapping);
358 if (!page)
359 break;
360
361 error = add_to_page_cache_lru(page, mapping, index,
Nick Piggin0ae0b5d2010-05-25 10:25:26 +0200362 GFP_KERNEL);
Jens Axboeeb207962006-04-27 11:05:22 +0200363 if (unlikely(error)) {
364 page_cache_release(page);
Jens Axboea0548872006-05-03 10:58:22 +0200365 if (error == -EEXIST)
366 continue;
Jens Axboeeb207962006-04-27 11:05:22 +0200367 break;
368 }
369 /*
370 * add_to_page_cache() locks the page, unlock it
371 * to avoid convoluting the logic below even more.
372 */
373 unlock_page(page);
374 }
375
Jens Axboe35f3d142010-05-20 10:43:18 +0200376 spd.pages[spd.nr_pages++] = page;
Jens Axboeeb207962006-04-27 11:05:22 +0200377 index++;
378 }
379
380 /*
381 * Now loop over the map and see if we need to start IO on any
382 * pages, fill in the partial map, etc.
383 */
384 index = *ppos >> PAGE_CACHE_SHIFT;
385 nr_pages = spd.nr_pages;
386 spd.nr_pages = 0;
387 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
Jens Axboe82aa5d62006-04-20 13:05:48 +0200388 unsigned int this_len;
389
390 if (!len)
391 break;
392
393 /*
394 * this_len is the max we'll use from this page
395 */
Andrew Mortonba5f5d92006-04-25 15:33:34 +0200396 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
Jens Axboe35f3d142010-05-20 10:43:18 +0200397 page = spd.pages[page_nr];
Jens Axboe7480a902006-04-11 13:52:47 +0200398
Fengguang Wua08a1662007-07-19 01:48:03 -0700399 if (PageReadahead(page))
Rusty Russellcf914a72007-07-19 01:48:08 -0700400 page_cache_async_readahead(mapping, &in->f_ra, in,
Fengguang Wud8983912007-07-19 01:48:06 -0700401 page, index, req_pages - page_nr);
Fengguang Wua08a1662007-07-19 01:48:03 -0700402
Jens Axboe7480a902006-04-11 13:52:47 +0200403 /*
404 * If the page isn't uptodate, we may need to start io on it
405 */
406 if (!PageUptodate(page)) {
Miklos Szeredi69650312010-08-03 12:48:50 +0200407 lock_page(page);
Jens Axboe7480a902006-04-11 13:52:47 +0200408
409 /*
Miklos Szeredi32502b82008-07-04 09:35:17 +0200410 * Page was truncated, or invalidated by the
411 * filesystem. Redo the find/create, but this time the
412 * page is kept locked, so there's no chance of another
413 * race with truncate/invalidate.
Jens Axboe7480a902006-04-11 13:52:47 +0200414 */
415 if (!page->mapping) {
416 unlock_page(page);
Miklos Szeredi32502b82008-07-04 09:35:17 +0200417 page = find_or_create_page(mapping, index,
418 mapping_gfp_mask(mapping));
419
420 if (!page) {
421 error = -ENOMEM;
422 break;
423 }
Jens Axboe35f3d142010-05-20 10:43:18 +0200424 page_cache_release(spd.pages[page_nr]);
425 spd.pages[page_nr] = page;
Jens Axboe7480a902006-04-11 13:52:47 +0200426 }
427 /*
428 * page was already under io and is now done, great
429 */
430 if (PageUptodate(page)) {
431 unlock_page(page);
432 goto fill_it;
433 }
434
Jens Axboe7480a902006-04-11 13:52:47 +0200435 /*
436 * need to read in the page
437 */
438 error = mapping->a_ops->readpage(in, page);
Jens Axboe7480a902006-04-11 13:52:47 +0200439 if (unlikely(error)) {
Jens Axboeeb207962006-04-27 11:05:22 +0200440 /*
441 * We really should re-lookup the page here,
442 * but it complicates things a lot. Instead
443 * lets just do what we already stored, and
444 * we'll get it the next time we are called.
445 */
Jens Axboe7480a902006-04-11 13:52:47 +0200446 if (error == AOP_TRUNCATED_PAGE)
Jens Axboeeb207962006-04-27 11:05:22 +0200447 error = 0;
448
Jens Axboe7480a902006-04-11 13:52:47 +0200449 break;
450 }
Jens Axboe620a3242007-06-07 09:39:42 +0200451 }
452fill_it:
453 /*
454 * i_size must be checked after PageUptodate.
455 */
456 isize = i_size_read(mapping->host);
457 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
458 if (unlikely(!isize || index > end_index))
459 break;
460
461 /*
462 * if this is the last page, see if we need to shrink
463 * the length and stop
464 */
465 if (end_index == index) {
466 unsigned int plen;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200467
468 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200469 * max good bytes in this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200470 */
Jens Axboe620a3242007-06-07 09:39:42 +0200471 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
472 if (plen <= loff)
Jens Axboe91ad66e2006-04-19 15:55:10 +0200473 break;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200474
475 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200476 * force quit after adding this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200477 */
Jens Axboe620a3242007-06-07 09:39:42 +0200478 this_len = min(this_len, plen - loff);
479 len = this_len;
Jens Axboe7480a902006-04-11 13:52:47 +0200480 }
Jens Axboe620a3242007-06-07 09:39:42 +0200481
Jens Axboe35f3d142010-05-20 10:43:18 +0200482 spd.partial[page_nr].offset = loff;
483 spd.partial[page_nr].len = this_len;
Jens Axboe82aa5d62006-04-20 13:05:48 +0200484 len -= this_len;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200485 loff = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200486 spd.nr_pages++;
487 index++;
Jens Axboe5274f052006-03-30 15:15:30 +0200488 }
489
Jens Axboeeb207962006-04-27 11:05:22 +0200490 /*
Hugh Dickins475ecad2007-06-07 09:36:00 +0200491 * Release any pages at the end, if we quit early. 'page_nr' is how far
Jens Axboeeb207962006-04-27 11:05:22 +0200492 * we got, 'nr_pages' is how many pages are in the map.
493 */
494 while (page_nr < nr_pages)
Jens Axboe35f3d142010-05-20 10:43:18 +0200495 page_cache_release(spd.pages[page_nr++]);
Fengguang Wuf4e6b492007-10-16 01:24:33 -0700496 in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
Jens Axboeeb207962006-04-27 11:05:22 +0200497
Jens Axboe912d35f2006-04-26 10:59:21 +0200498 if (spd.nr_pages)
Jens Axboe35f3d142010-05-20 10:43:18 +0200499 error = splice_to_pipe(pipe, &spd);
Jens Axboe5274f052006-03-30 15:15:30 +0200500
Eric Dumazet047fe362012-06-12 15:24:40 +0200501 splice_shrink_spd(&spd);
Jens Axboe7480a902006-04-11 13:52:47 +0200502 return error;
Jens Axboe5274f052006-03-30 15:15:30 +0200503}
504
Jens Axboe83f91352006-04-02 23:05:09 +0200505/**
506 * generic_file_splice_read - splice data from file to a pipe
507 * @in: file to splice from
Jens Axboe932cc6d2007-06-21 13:10:21 +0200508 * @ppos: position in @in
Jens Axboe83f91352006-04-02 23:05:09 +0200509 * @pipe: pipe to splice to
510 * @len: number of bytes to splice
511 * @flags: splice modifier flags
512 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200513 * Description:
514 * Will read pages from given file and fill them into a pipe. Can be
515 * used as long as the address_space operations for the source implements
516 * a readpage() hook.
517 *
Jens Axboe83f91352006-04-02 23:05:09 +0200518 */
Jens Axboecbb7e572006-04-11 14:57:50 +0200519ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
520 struct pipe_inode_info *pipe, size_t len,
521 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200522{
Jens Axboed366d3982007-06-01 14:54:11 +0200523 loff_t isize, left;
Jens Axboe8191ecd2008-04-10 08:24:25 +0200524 int ret;
Jens Axboed366d3982007-06-01 14:54:11 +0200525
Boaz Harroshbe64f882015-04-15 16:15:17 -0700526 if (IS_DAX(in->f_mapping->host))
527 return default_file_splice_read(in, ppos, pipe, len, flags);
528
Jens Axboed366d3982007-06-01 14:54:11 +0200529 isize = i_size_read(in->f_mapping->host);
530 if (unlikely(*ppos >= isize))
531 return 0;
532
533 left = isize - *ppos;
534 if (unlikely(left < len))
535 len = left;
Jens Axboe5274f052006-03-30 15:15:30 +0200536
Jens Axboe8191ecd2008-04-10 08:24:25 +0200537 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
Miklos Szeredi723590e2009-08-15 08:43:22 +0200538 if (ret > 0) {
Jens Axboecbb7e572006-04-11 14:57:50 +0200539 *ppos += ret;
Miklos Szeredi723590e2009-08-15 08:43:22 +0200540 file_accessed(in);
541 }
Jens Axboe5274f052006-03-30 15:15:30 +0200542
543 return ret;
544}
Jens Axboe059a8f32006-04-02 23:06:05 +0200545EXPORT_SYMBOL(generic_file_splice_read);
546
Miklos Szeredi68181732009-05-07 15:37:36 +0200547static const struct pipe_buf_operations default_pipe_buf_ops = {
548 .can_merge = 0,
Miklos Szeredi68181732009-05-07 15:37:36 +0200549 .confirm = generic_pipe_buf_confirm,
550 .release = generic_pipe_buf_release,
551 .steal = generic_pipe_buf_steal,
552 .get = generic_pipe_buf_get,
553};
554
Miklos Szeredi28a625c2014-01-22 19:36:57 +0100555static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
556 struct pipe_buffer *buf)
557{
558 return 1;
559}
560
561/* Pipe buffer operations for a socket and similar. */
562const struct pipe_buf_operations nosteal_pipe_buf_ops = {
563 .can_merge = 0,
Miklos Szeredi28a625c2014-01-22 19:36:57 +0100564 .confirm = generic_pipe_buf_confirm,
565 .release = generic_pipe_buf_release,
566 .steal = generic_pipe_buf_nosteal,
567 .get = generic_pipe_buf_get,
568};
569EXPORT_SYMBOL(nosteal_pipe_buf_ops);
570
Miklos Szeredi68181732009-05-07 15:37:36 +0200571static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
572 unsigned long vlen, loff_t offset)
573{
574 mm_segment_t old_fs;
575 loff_t pos = offset;
576 ssize_t res;
577
578 old_fs = get_fs();
579 set_fs(get_ds());
580 /* The cast to a user pointer is valid due to the set_fs() */
581 res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos);
582 set_fs(old_fs);
583
584 return res;
585}
586
Al Viro7bb307e2013-02-23 14:51:48 -0500587ssize_t kernel_write(struct file *file, const char *buf, size_t count,
Miklos Szeredib2858d72009-05-19 11:37:46 +0200588 loff_t pos)
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200589{
590 mm_segment_t old_fs;
591 ssize_t res;
592
593 old_fs = get_fs();
594 set_fs(get_ds());
595 /* The cast to a user pointer is valid due to the set_fs() */
Al Viro7bb307e2013-02-23 14:51:48 -0500596 res = vfs_write(file, (__force const char __user *)buf, count, &pos);
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200597 set_fs(old_fs);
598
599 return res;
600}
Al Viro7bb307e2013-02-23 14:51:48 -0500601EXPORT_SYMBOL(kernel_write);
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200602
Miklos Szeredi68181732009-05-07 15:37:36 +0200603ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
604 struct pipe_inode_info *pipe, size_t len,
605 unsigned int flags)
606{
607 unsigned int nr_pages;
608 unsigned int nr_freed;
609 size_t offset;
Jens Axboe35f3d142010-05-20 10:43:18 +0200610 struct page *pages[PIPE_DEF_BUFFERS];
611 struct partial_page partial[PIPE_DEF_BUFFERS];
612 struct iovec *vec, __vec[PIPE_DEF_BUFFERS];
Miklos Szeredi68181732009-05-07 15:37:36 +0200613 ssize_t res;
614 size_t this_len;
615 int error;
616 int i;
617 struct splice_pipe_desc spd = {
618 .pages = pages,
619 .partial = partial,
Eric Dumazet047fe362012-06-12 15:24:40 +0200620 .nr_pages_max = PIPE_DEF_BUFFERS,
Miklos Szeredi68181732009-05-07 15:37:36 +0200621 .flags = flags,
622 .ops = &default_pipe_buf_ops,
623 .spd_release = spd_release_page,
624 };
625
Jens Axboe35f3d142010-05-20 10:43:18 +0200626 if (splice_grow_spd(pipe, &spd))
627 return -ENOMEM;
628
629 res = -ENOMEM;
630 vec = __vec;
Eric Dumazet047fe362012-06-12 15:24:40 +0200631 if (spd.nr_pages_max > PIPE_DEF_BUFFERS) {
632 vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL);
Jens Axboe35f3d142010-05-20 10:43:18 +0200633 if (!vec)
634 goto shrink_ret;
635 }
636
Miklos Szeredi68181732009-05-07 15:37:36 +0200637 offset = *ppos & ~PAGE_CACHE_MASK;
638 nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
639
Eric Dumazet047fe362012-06-12 15:24:40 +0200640 for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) {
Miklos Szeredi68181732009-05-07 15:37:36 +0200641 struct page *page;
642
Jens Axboe4f231222009-05-13 08:35:35 +0200643 page = alloc_page(GFP_USER);
Miklos Szeredi68181732009-05-07 15:37:36 +0200644 error = -ENOMEM;
645 if (!page)
646 goto err;
647
648 this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset);
Jens Axboe4f231222009-05-13 08:35:35 +0200649 vec[i].iov_base = (void __user *) page_address(page);
Miklos Szeredi68181732009-05-07 15:37:36 +0200650 vec[i].iov_len = this_len;
Jens Axboe35f3d142010-05-20 10:43:18 +0200651 spd.pages[i] = page;
Miklos Szeredi68181732009-05-07 15:37:36 +0200652 spd.nr_pages++;
653 len -= this_len;
654 offset = 0;
655 }
656
657 res = kernel_readv(in, vec, spd.nr_pages, *ppos);
Andrew Morton77f6bf52009-05-14 09:49:44 +0200658 if (res < 0) {
659 error = res;
Miklos Szeredi68181732009-05-07 15:37:36 +0200660 goto err;
Andrew Morton77f6bf52009-05-14 09:49:44 +0200661 }
Miklos Szeredi68181732009-05-07 15:37:36 +0200662
663 error = 0;
664 if (!res)
665 goto err;
666
667 nr_freed = 0;
668 for (i = 0; i < spd.nr_pages; i++) {
Miklos Szeredi68181732009-05-07 15:37:36 +0200669 this_len = min_t(size_t, vec[i].iov_len, res);
Jens Axboe35f3d142010-05-20 10:43:18 +0200670 spd.partial[i].offset = 0;
671 spd.partial[i].len = this_len;
Miklos Szeredi68181732009-05-07 15:37:36 +0200672 if (!this_len) {
Jens Axboe35f3d142010-05-20 10:43:18 +0200673 __free_page(spd.pages[i]);
674 spd.pages[i] = NULL;
Miklos Szeredi68181732009-05-07 15:37:36 +0200675 nr_freed++;
676 }
677 res -= this_len;
678 }
679 spd.nr_pages -= nr_freed;
680
681 res = splice_to_pipe(pipe, &spd);
682 if (res > 0)
683 *ppos += res;
684
Jens Axboe35f3d142010-05-20 10:43:18 +0200685shrink_ret:
686 if (vec != __vec)
687 kfree(vec);
Eric Dumazet047fe362012-06-12 15:24:40 +0200688 splice_shrink_spd(&spd);
Miklos Szeredi68181732009-05-07 15:37:36 +0200689 return res;
690
691err:
Jens Axboe4f231222009-05-13 08:35:35 +0200692 for (i = 0; i < spd.nr_pages; i++)
Jens Axboe35f3d142010-05-20 10:43:18 +0200693 __free_page(spd.pages[i]);
Jens Axboe4f231222009-05-13 08:35:35 +0200694
Jens Axboe35f3d142010-05-20 10:43:18 +0200695 res = error;
696 goto shrink_ret;
Miklos Szeredi68181732009-05-07 15:37:36 +0200697}
698EXPORT_SYMBOL(default_file_splice_read);
699
Jens Axboe5274f052006-03-30 15:15:30 +0200700/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200701 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
Jens Axboe016b6612006-04-25 15:42:00 +0200702 * using sendpage(). Return the number of bytes sent.
Jens Axboe5274f052006-03-30 15:15:30 +0200703 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200704static int pipe_to_sendpage(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +0200705 struct pipe_buffer *buf, struct splice_desc *sd)
706{
Jens Axboe6a14b902007-06-14 13:08:55 +0200707 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200708 loff_t pos = sd->pos;
Michał Mirosława8adbe32010-12-17 08:56:44 +0100709 int more;
Jens Axboe5274f052006-03-30 15:15:30 +0200710
Al Viro72c2d532013-09-22 16:27:52 -0400711 if (!likely(file->f_op->sendpage))
Michał Mirosława8adbe32010-12-17 08:56:44 +0100712 return -EINVAL;
Jens Axboe5274f052006-03-30 15:15:30 +0200713
Eric Dumazet35f9c092012-04-05 03:05:35 +0000714 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
Eric Dumazetae62ca72013-01-06 18:21:49 +0000715
716 if (sd->len < sd->total_len && pipe->nrbufs > 1)
Eric Dumazet35f9c092012-04-05 03:05:35 +0000717 more |= MSG_SENDPAGE_NOTLAST;
Eric Dumazetae62ca72013-01-06 18:21:49 +0000718
Michał Mirosława8adbe32010-12-17 08:56:44 +0100719 return file->f_op->sendpage(file, buf->page, buf->offset,
720 sd->len, &pos, more);
Jens Axboe5274f052006-03-30 15:15:30 +0200721}
722
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200723static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
724{
725 smp_mb();
726 if (waitqueue_active(&pipe->wait))
727 wake_up_interruptible(&pipe->wait);
728 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
729}
730
731/**
732 * splice_from_pipe_feed - feed available data from a pipe to a file
733 * @pipe: pipe to splice from
734 * @sd: information to @actor
735 * @actor: handler that splices the data
736 *
737 * Description:
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200738 * This function loops over the pipe and calls @actor to do the
739 * actual moving of a single struct pipe_buffer to the desired
740 * destination. It returns when there's no more buffers left in
741 * the pipe or if the requested number of bytes (@sd->total_len)
742 * have been copied. It returns a positive number (one) if the
743 * pipe needs to be filled with more data, zero if the required
744 * number of bytes have been copied and -errno on error.
745 *
746 * This, together with splice_from_pipe_{begin,end,next}, may be
747 * used to implement the functionality of __splice_from_pipe() when
748 * locking is required around copying the pipe buffers to the
749 * destination.
750 */
Al Viro96f9bc82014-04-05 04:35:49 -0400751static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200752 splice_actor *actor)
753{
754 int ret;
755
756 while (pipe->nrbufs) {
757 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
758 const struct pipe_buf_operations *ops = buf->ops;
759
760 sd->len = buf->len;
761 if (sd->len > sd->total_len)
762 sd->len = sd->total_len;
763
Michał Mirosława8adbe32010-12-17 08:56:44 +0100764 ret = buf->ops->confirm(pipe, buf);
765 if (unlikely(ret)) {
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200766 if (ret == -ENODATA)
767 ret = 0;
768 return ret;
769 }
Michał Mirosława8adbe32010-12-17 08:56:44 +0100770
771 ret = actor(pipe, buf, sd);
772 if (ret <= 0)
773 return ret;
774
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200775 buf->offset += ret;
776 buf->len -= ret;
777
778 sd->num_spliced += ret;
779 sd->len -= ret;
780 sd->pos += ret;
781 sd->total_len -= ret;
782
783 if (!buf->len) {
784 buf->ops = NULL;
785 ops->release(pipe, buf);
Jens Axboe35f3d142010-05-20 10:43:18 +0200786 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200787 pipe->nrbufs--;
Al Viro6447a3c2013-03-21 11:01:38 -0400788 if (pipe->files)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200789 sd->need_wakeup = true;
790 }
791
792 if (!sd->total_len)
793 return 0;
794 }
795
796 return 1;
797}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200798
799/**
800 * splice_from_pipe_next - wait for some data to splice from
801 * @pipe: pipe to splice from
802 * @sd: information about the splice operation
803 *
804 * Description:
805 * This function will wait for some data and return a positive
806 * value (one) if pipe buffers are available. It will return zero
807 * or -errno if no more data needs to be spliced.
808 */
Al Viro96f9bc82014-04-05 04:35:49 -0400809static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200810{
811 while (!pipe->nrbufs) {
812 if (!pipe->writers)
813 return 0;
814
815 if (!pipe->waiting_writers && sd->num_spliced)
816 return 0;
817
818 if (sd->flags & SPLICE_F_NONBLOCK)
819 return -EAGAIN;
820
821 if (signal_pending(current))
822 return -ERESTARTSYS;
823
824 if (sd->need_wakeup) {
825 wakeup_pipe_writers(pipe);
826 sd->need_wakeup = false;
827 }
828
829 pipe_wait(pipe);
830 }
831
832 return 1;
833}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200834
835/**
836 * splice_from_pipe_begin - start splicing from pipe
Randy Dunlapb80901b2009-04-16 19:09:55 -0700837 * @sd: information about the splice operation
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200838 *
839 * Description:
840 * This function should be called before a loop containing
841 * splice_from_pipe_next() and splice_from_pipe_feed() to
842 * initialize the necessary fields of @sd.
843 */
Al Viro96f9bc82014-04-05 04:35:49 -0400844static void splice_from_pipe_begin(struct splice_desc *sd)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200845{
846 sd->num_spliced = 0;
847 sd->need_wakeup = false;
848}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200849
850/**
851 * splice_from_pipe_end - finish splicing from pipe
852 * @pipe: pipe to splice from
853 * @sd: information about the splice operation
854 *
855 * Description:
856 * This function will wake up pipe writers if necessary. It should
857 * be called after a loop containing splice_from_pipe_next() and
858 * splice_from_pipe_feed().
859 */
Al Viro96f9bc82014-04-05 04:35:49 -0400860static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200861{
862 if (sd->need_wakeup)
863 wakeup_pipe_writers(pipe);
864}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200865
Jens Axboe932cc6d2007-06-21 13:10:21 +0200866/**
867 * __splice_from_pipe - splice data from a pipe to given actor
868 * @pipe: pipe to splice from
869 * @sd: information to @actor
870 * @actor: handler that splices the data
871 *
872 * Description:
873 * This function does little more than loop over the pipe and call
874 * @actor to do the actual moving of a single struct pipe_buffer to
875 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
876 * pipe_to_user.
877 *
Jens Axboe83f91352006-04-02 23:05:09 +0200878 */
Jens Axboec66ab6f2007-06-12 21:17:17 +0200879ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
880 splice_actor *actor)
Jens Axboe5274f052006-03-30 15:15:30 +0200881{
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200882 int ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200883
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200884 splice_from_pipe_begin(sd);
885 do {
886 ret = splice_from_pipe_next(pipe, sd);
887 if (ret > 0)
888 ret = splice_from_pipe_feed(pipe, sd, actor);
889 } while (ret > 0);
890 splice_from_pipe_end(pipe, sd);
Jens Axboe5274f052006-03-30 15:15:30 +0200891
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200892 return sd->num_spliced ? sd->num_spliced : ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200893}
Mark Fasheh40bee44e2007-03-21 13:11:02 +0100894EXPORT_SYMBOL(__splice_from_pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200895
Jens Axboe932cc6d2007-06-21 13:10:21 +0200896/**
897 * splice_from_pipe - splice data from a pipe to a file
898 * @pipe: pipe to splice from
899 * @out: file to splice to
900 * @ppos: position in @out
901 * @len: how many bytes to splice
902 * @flags: splice modifier flags
903 * @actor: handler that splices the data
904 *
905 * Description:
Miklos Szeredi29339702009-04-14 19:48:37 +0200906 * See __splice_from_pipe. This function locks the pipe inode,
Jens Axboe932cc6d2007-06-21 13:10:21 +0200907 * otherwise it's identical to __splice_from_pipe().
908 *
909 */
Mark Fasheh6da61802006-10-17 18:43:07 +0200910ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
911 loff_t *ppos, size_t len, unsigned int flags,
912 splice_actor *actor)
913{
914 ssize_t ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200915 struct splice_desc sd = {
916 .total_len = len,
917 .flags = flags,
918 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +0200919 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +0200920 };
Mark Fasheh6da61802006-10-17 18:43:07 +0200921
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200922 pipe_lock(pipe);
Jens Axboec66ab6f2007-06-12 21:17:17 +0200923 ret = __splice_from_pipe(pipe, &sd, actor);
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200924 pipe_unlock(pipe);
Mark Fasheh6da61802006-10-17 18:43:07 +0200925
926 return ret;
927}
928
929/**
Al Viro8d020762014-04-05 04:27:08 -0400930 * iter_file_splice_write - splice data from a pipe to a file
931 * @pipe: pipe info
932 * @out: file to write to
933 * @ppos: position in @out
934 * @len: number of bytes to splice
935 * @flags: splice modifier flags
936 *
937 * Description:
938 * Will either move or copy pages (determined by @flags options) from
939 * the given pipe inode to the given file.
940 * This one is ->write_iter-based.
941 *
942 */
943ssize_t
944iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
945 loff_t *ppos, size_t len, unsigned int flags)
946{
947 struct splice_desc sd = {
948 .total_len = len,
949 .flags = flags,
950 .pos = *ppos,
951 .u.file = out,
952 };
953 int nbufs = pipe->buffers;
954 struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
955 GFP_KERNEL);
956 ssize_t ret;
957
958 if (unlikely(!array))
959 return -ENOMEM;
960
961 pipe_lock(pipe);
962
963 splice_from_pipe_begin(&sd);
964 while (sd.total_len) {
965 struct iov_iter from;
Al Viro8d020762014-04-05 04:27:08 -0400966 size_t left;
967 int n, idx;
968
969 ret = splice_from_pipe_next(pipe, &sd);
970 if (ret <= 0)
971 break;
972
973 if (unlikely(nbufs < pipe->buffers)) {
974 kfree(array);
975 nbufs = pipe->buffers;
976 array = kcalloc(nbufs, sizeof(struct bio_vec),
977 GFP_KERNEL);
978 if (!array) {
979 ret = -ENOMEM;
980 break;
981 }
982 }
983
984 /* build the vector */
985 left = sd.total_len;
986 for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) {
987 struct pipe_buffer *buf = pipe->bufs + idx;
988 size_t this_len = buf->len;
989
990 if (this_len > left)
991 this_len = left;
992
993 if (idx == pipe->buffers - 1)
994 idx = -1;
995
996 ret = buf->ops->confirm(pipe, buf);
997 if (unlikely(ret)) {
998 if (ret == -ENODATA)
999 ret = 0;
1000 goto done;
1001 }
1002
1003 array[n].bv_page = buf->page;
1004 array[n].bv_len = this_len;
1005 array[n].bv_offset = buf->offset;
1006 left -= this_len;
1007 }
1008
Al Viro05afcb72015-01-23 01:08:07 -05001009 iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
1010 sd.total_len - left);
Christoph Hellwigdbe4e192015-01-25 21:11:59 +01001011 ret = vfs_iter_write(out, &from, &sd.pos);
Al Viro8d020762014-04-05 04:27:08 -04001012 if (ret <= 0)
1013 break;
1014
1015 sd.num_spliced += ret;
1016 sd.total_len -= ret;
Christoph Hellwigdbe4e192015-01-25 21:11:59 +01001017 *ppos = sd.pos;
Al Viro8d020762014-04-05 04:27:08 -04001018
1019 /* dismiss the fully eaten buffers, adjust the partial one */
1020 while (ret) {
1021 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
1022 if (ret >= buf->len) {
1023 const struct pipe_buf_operations *ops = buf->ops;
1024 ret -= buf->len;
1025 buf->len = 0;
1026 buf->ops = NULL;
1027 ops->release(pipe, buf);
1028 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
1029 pipe->nrbufs--;
1030 if (pipe->files)
1031 sd.need_wakeup = true;
1032 } else {
1033 buf->offset += ret;
1034 buf->len -= ret;
1035 ret = 0;
1036 }
1037 }
1038 }
1039done:
1040 kfree(array);
1041 splice_from_pipe_end(pipe, &sd);
1042
1043 pipe_unlock(pipe);
1044
1045 if (sd.num_spliced)
1046 ret = sd.num_spliced;
1047
1048 return ret;
1049}
1050
1051EXPORT_SYMBOL(iter_file_splice_write);
1052
Miklos Szeredib2858d72009-05-19 11:37:46 +02001053static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1054 struct splice_desc *sd)
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001055{
Miklos Szeredib2858d72009-05-19 11:37:46 +02001056 int ret;
1057 void *data;
Al Viro06ae43f2013-03-20 13:19:30 -04001058 loff_t tmp = sd->pos;
Miklos Szeredib2858d72009-05-19 11:37:46 +02001059
Al Virofbb32752014-02-02 21:09:54 -05001060 data = kmap(buf->page);
Al Viro06ae43f2013-03-20 13:19:30 -04001061 ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
Al Virofbb32752014-02-02 21:09:54 -05001062 kunmap(buf->page);
Miklos Szeredib2858d72009-05-19 11:37:46 +02001063
1064 return ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001065}
1066
1067static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
1068 struct file *out, loff_t *ppos,
1069 size_t len, unsigned int flags)
1070{
Miklos Szeredib2858d72009-05-19 11:37:46 +02001071 ssize_t ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001072
Miklos Szeredib2858d72009-05-19 11:37:46 +02001073 ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
1074 if (ret > 0)
1075 *ppos += ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001076
Miklos Szeredib2858d72009-05-19 11:37:46 +02001077 return ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001078}
1079
Jens Axboe83f91352006-04-02 23:05:09 +02001080/**
1081 * generic_splice_sendpage - splice data from a pipe to a socket
Jens Axboe932cc6d2007-06-21 13:10:21 +02001082 * @pipe: pipe to splice from
Jens Axboe83f91352006-04-02 23:05:09 +02001083 * @out: socket to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +02001084 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +02001085 * @len: number of bytes to splice
1086 * @flags: splice modifier flags
1087 *
Jens Axboe932cc6d2007-06-21 13:10:21 +02001088 * Description:
1089 * Will send @len bytes from the pipe to a network socket. No data copying
1090 * is involved.
Jens Axboe83f91352006-04-02 23:05:09 +02001091 *
1092 */
Ingo Molnar3a326a22006-04-10 15:18:35 +02001093ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +02001094 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001095{
Jens Axboe00522fb2006-04-26 14:39:29 +02001096 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
Jens Axboe5274f052006-03-30 15:15:30 +02001097}
1098
Jens Axboe059a8f32006-04-02 23:06:05 +02001099EXPORT_SYMBOL(generic_splice_sendpage);
Jeff Garzika0f06782006-03-30 23:06:13 -05001100
Jens Axboe83f91352006-04-02 23:05:09 +02001101/*
1102 * Attempt to initiate a splice from pipe to file.
1103 */
Ingo Molnar3a326a22006-04-10 15:18:35 +02001104static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +02001105 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001106{
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001107 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
1108 loff_t *, size_t, unsigned int);
Jens Axboe5274f052006-03-30 15:15:30 +02001109
Al Viro72c2d532013-09-22 16:27:52 -04001110 if (out->f_op->splice_write)
Changli Gaocc56f7d2009-11-04 09:09:52 +01001111 splice_write = out->f_op->splice_write;
1112 else
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001113 splice_write = default_file_splice_write;
1114
Al Viro500368f2013-05-23 20:07:11 -04001115 return splice_write(pipe, out, ppos, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001116}
1117
Jens Axboe83f91352006-04-02 23:05:09 +02001118/*
1119 * Attempt to initiate a splice from a file to a pipe.
1120 */
Jens Axboecbb7e572006-04-11 14:57:50 +02001121static long do_splice_to(struct file *in, loff_t *ppos,
1122 struct pipe_inode_info *pipe, size_t len,
1123 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001124{
Miklos Szeredi68181732009-05-07 15:37:36 +02001125 ssize_t (*splice_read)(struct file *, loff_t *,
1126 struct pipe_inode_info *, size_t, unsigned int);
Jens Axboe5274f052006-03-30 15:15:30 +02001127 int ret;
1128
Jens Axboe49570e92006-04-11 13:56:09 +02001129 if (unlikely(!(in->f_mode & FMODE_READ)))
Jens Axboe5274f052006-03-30 15:15:30 +02001130 return -EBADF;
1131
Jens Axboecbb7e572006-04-11 14:57:50 +02001132 ret = rw_verify_area(READ, in, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +02001133 if (unlikely(ret < 0))
1134 return ret;
1135
Al Viro72c2d532013-09-22 16:27:52 -04001136 if (in->f_op->splice_read)
Changli Gaocc56f7d2009-11-04 09:09:52 +01001137 splice_read = in->f_op->splice_read;
1138 else
Miklos Szeredi68181732009-05-07 15:37:36 +02001139 splice_read = default_file_splice_read;
1140
1141 return splice_read(in, ppos, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001142}
1143
Jens Axboe932cc6d2007-06-21 13:10:21 +02001144/**
1145 * splice_direct_to_actor - splices data directly between two non-pipes
1146 * @in: file to splice from
1147 * @sd: actor information on where to splice to
1148 * @actor: handles the data splicing
1149 *
1150 * Description:
1151 * This is a special case helper to splice directly between two
1152 * points, without requiring an explicit pipe. Internally an allocated
Randy Dunlap79685b82007-07-27 08:08:51 +02001153 * pipe is cached in the process, and reused during the lifetime of
Jens Axboe932cc6d2007-06-21 13:10:21 +02001154 * that process.
1155 *
Jens Axboec66ab6f2007-06-12 21:17:17 +02001156 */
1157ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
1158 splice_direct_actor *actor)
Jens Axboeb92ce552006-04-11 13:52:07 +02001159{
1160 struct pipe_inode_info *pipe;
1161 long ret, bytes;
1162 umode_t i_mode;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001163 size_t len;
1164 int i, flags;
Jens Axboeb92ce552006-04-11 13:52:07 +02001165
1166 /*
1167 * We require the input being a regular file, as we don't want to
1168 * randomly drop data for eg socket -> socket splicing. Use the
1169 * piped splicing for that!
1170 */
Al Viro496ad9a2013-01-23 17:07:38 -05001171 i_mode = file_inode(in)->i_mode;
Jens Axboeb92ce552006-04-11 13:52:07 +02001172 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
1173 return -EINVAL;
1174
1175 /*
1176 * neither in nor out is a pipe, setup an internal pipe attached to
1177 * 'out' and transfer the wanted data from 'in' to 'out' through that
1178 */
1179 pipe = current->splice_pipe;
Jens Axboe49570e92006-04-11 13:56:09 +02001180 if (unlikely(!pipe)) {
Al Viro7bee1302013-03-21 11:04:15 -04001181 pipe = alloc_pipe_info();
Jens Axboeb92ce552006-04-11 13:52:07 +02001182 if (!pipe)
1183 return -ENOMEM;
1184
1185 /*
1186 * We don't have an immediate reader, but we'll read the stuff
Jens Axboe00522fb2006-04-26 14:39:29 +02001187 * out of the pipe right after the splice_to_pipe(). So set
Jens Axboeb92ce552006-04-11 13:52:07 +02001188 * PIPE_READERS appropriately.
1189 */
1190 pipe->readers = 1;
1191
1192 current->splice_pipe = pipe;
1193 }
1194
1195 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +02001196 * Do the splice.
Jens Axboeb92ce552006-04-11 13:52:07 +02001197 */
1198 ret = 0;
1199 bytes = 0;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001200 len = sd->total_len;
1201 flags = sd->flags;
1202
1203 /*
1204 * Don't block on output, we have to drain the direct pipe.
1205 */
1206 sd->flags &= ~SPLICE_F_NONBLOCK;
Jens Axboeb92ce552006-04-11 13:52:07 +02001207
1208 while (len) {
Jens Axboe51a92c02007-07-13 14:11:43 +02001209 size_t read_len;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001210 loff_t pos = sd->pos, prev_pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001211
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001212 ret = do_splice_to(in, &pos, pipe, len, flags);
Jens Axboe51a92c02007-07-13 14:11:43 +02001213 if (unlikely(ret <= 0))
Jens Axboeb92ce552006-04-11 13:52:07 +02001214 goto out_release;
1215
1216 read_len = ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001217 sd->total_len = read_len;
Jens Axboeb92ce552006-04-11 13:52:07 +02001218
1219 /*
1220 * NOTE: nonblocking mode only applies to the input. We
1221 * must not do the output in nonblocking mode as then we
1222 * could get stuck data in the internal pipe:
1223 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001224 ret = actor(pipe, sd);
Tom Zanussia82c53a2008-05-09 13:28:36 +02001225 if (unlikely(ret <= 0)) {
1226 sd->pos = prev_pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001227 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001228 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001229
1230 bytes += ret;
1231 len -= ret;
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001232 sd->pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001233
Tom Zanussia82c53a2008-05-09 13:28:36 +02001234 if (ret < read_len) {
1235 sd->pos = prev_pos + ret;
Jens Axboe51a92c02007-07-13 14:11:43 +02001236 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001237 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001238 }
1239
Jens Axboe9e971982008-01-29 21:05:57 +01001240done:
Jens Axboeb92ce552006-04-11 13:52:07 +02001241 pipe->nrbufs = pipe->curbuf = 0;
Jens Axboe80848702008-01-30 12:24:48 +01001242 file_accessed(in);
Jens Axboeb92ce552006-04-11 13:52:07 +02001243 return bytes;
1244
1245out_release:
1246 /*
1247 * If we did an incomplete transfer we must release
1248 * the pipe buffers in question:
1249 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001250 for (i = 0; i < pipe->buffers; i++) {
Jens Axboeb92ce552006-04-11 13:52:07 +02001251 struct pipe_buffer *buf = pipe->bufs + i;
1252
1253 if (buf->ops) {
1254 buf->ops->release(pipe, buf);
1255 buf->ops = NULL;
1256 }
1257 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001258
Jens Axboe9e971982008-01-29 21:05:57 +01001259 if (!bytes)
1260 bytes = ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001261
Jens Axboe9e971982008-01-29 21:05:57 +01001262 goto done;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001263}
1264EXPORT_SYMBOL(splice_direct_to_actor);
1265
1266static int direct_splice_actor(struct pipe_inode_info *pipe,
1267 struct splice_desc *sd)
1268{
Jens Axboe6a14b902007-06-14 13:08:55 +02001269 struct file *file = sd->u.file;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001270
Al Viro7995bd22013-06-20 18:58:36 +04001271 return do_splice_from(pipe, file, sd->opos, sd->total_len,
Changli Gao2cb4b052010-06-29 13:09:18 +02001272 sd->flags);
Jens Axboec66ab6f2007-06-12 21:17:17 +02001273}
1274
Jens Axboe932cc6d2007-06-21 13:10:21 +02001275/**
1276 * do_splice_direct - splices data directly between two files
1277 * @in: file to splice from
1278 * @ppos: input file offset
1279 * @out: file to splice to
Randy Dunlapacdb37c2013-06-22 19:44:08 -07001280 * @opos: output file offset
Jens Axboe932cc6d2007-06-21 13:10:21 +02001281 * @len: number of bytes to splice
1282 * @flags: splice modifier flags
1283 *
1284 * Description:
1285 * For use by do_sendfile(). splice can easily emulate sendfile, but
1286 * doing it in the application would incur an extra system call
1287 * (splice in + splice out, as compared to just sendfile()). So this helper
1288 * can splice directly through a process-private pipe.
1289 *
1290 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001291long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
Al Viro7995bd22013-06-20 18:58:36 +04001292 loff_t *opos, size_t len, unsigned int flags)
Jens Axboec66ab6f2007-06-12 21:17:17 +02001293{
1294 struct splice_desc sd = {
1295 .len = len,
1296 .total_len = len,
1297 .flags = flags,
1298 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +02001299 .u.file = out,
Al Viro7995bd22013-06-20 18:58:36 +04001300 .opos = opos,
Jens Axboec66ab6f2007-06-12 21:17:17 +02001301 };
Jens Axboe51a92c02007-07-13 14:11:43 +02001302 long ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001303
Al Viro18c67cb2013-06-19 15:41:54 +04001304 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1305 return -EBADF;
1306
1307 if (unlikely(out->f_flags & O_APPEND))
1308 return -EINVAL;
1309
1310 ret = rw_verify_area(WRITE, out, opos, len);
1311 if (unlikely(ret < 0))
1312 return ret;
1313
Jens Axboec66ab6f2007-06-12 21:17:17 +02001314 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
Jens Axboe51a92c02007-07-13 14:11:43 +02001315 if (ret > 0)
Tom Zanussia82c53a2008-05-09 13:28:36 +02001316 *ppos = sd.pos;
Jens Axboe51a92c02007-07-13 14:11:43 +02001317
Jens Axboec66ab6f2007-06-12 21:17:17 +02001318 return ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001319}
Miklos Szeredi1c118592014-10-24 00:14:35 +02001320EXPORT_SYMBOL(do_splice_direct);
Jens Axboeb92ce552006-04-11 13:52:07 +02001321
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001322static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1323 struct pipe_inode_info *opipe,
1324 size_t len, unsigned int flags);
Jens Axboeddac0d32006-11-04 12:49:32 +01001325
1326/*
Jens Axboe83f91352006-04-02 23:05:09 +02001327 * Determine where to splice to/from.
1328 */
Ingo Molnar529565d2006-04-10 15:18:58 +02001329static long do_splice(struct file *in, loff_t __user *off_in,
1330 struct file *out, loff_t __user *off_out,
1331 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001332{
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001333 struct pipe_inode_info *ipipe;
1334 struct pipe_inode_info *opipe;
Al Viro7995bd22013-06-20 18:58:36 +04001335 loff_t offset;
Jens Axboea4514eb2006-04-19 15:57:05 +02001336 long ret;
Jens Axboe5274f052006-03-30 15:15:30 +02001337
Linus Torvalds71993e62010-11-28 13:56:09 -08001338 ipipe = get_pipe_info(in);
1339 opipe = get_pipe_info(out);
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001340
1341 if (ipipe && opipe) {
1342 if (off_in || off_out)
1343 return -ESPIPE;
1344
1345 if (!(in->f_mode & FMODE_READ))
1346 return -EBADF;
1347
1348 if (!(out->f_mode & FMODE_WRITE))
1349 return -EBADF;
1350
1351 /* Splicing to self would be fun, but... */
1352 if (ipipe == opipe)
1353 return -EINVAL;
1354
1355 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1356 }
1357
1358 if (ipipe) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001359 if (off_in)
1360 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001361 if (off_out) {
Changli Gao19c9a492010-06-29 13:10:36 +02001362 if (!(out->f_mode & FMODE_PWRITE))
Jens Axboeb92ce552006-04-11 13:52:07 +02001363 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001364 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001365 return -EFAULT;
Al Viro7995bd22013-06-20 18:58:36 +04001366 } else {
1367 offset = out->f_pos;
1368 }
Ingo Molnar529565d2006-04-10 15:18:58 +02001369
Al Viro18c67cb2013-06-19 15:41:54 +04001370 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1371 return -EBADF;
1372
1373 if (unlikely(out->f_flags & O_APPEND))
1374 return -EINVAL;
1375
1376 ret = rw_verify_area(WRITE, out, &offset, len);
1377 if (unlikely(ret < 0))
1378 return ret;
1379
Al Viro500368f2013-05-23 20:07:11 -04001380 file_start_write(out);
Al Viro7995bd22013-06-20 18:58:36 +04001381 ret = do_splice_from(ipipe, out, &offset, len, flags);
Al Viro500368f2013-05-23 20:07:11 -04001382 file_end_write(out);
Jens Axboea4514eb2006-04-19 15:57:05 +02001383
Al Viro7995bd22013-06-20 18:58:36 +04001384 if (!off_out)
1385 out->f_pos = offset;
1386 else if (copy_to_user(off_out, &offset, sizeof(loff_t)))
Jens Axboea4514eb2006-04-19 15:57:05 +02001387 ret = -EFAULT;
1388
1389 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001390 }
Jens Axboe5274f052006-03-30 15:15:30 +02001391
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001392 if (opipe) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001393 if (off_out)
1394 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001395 if (off_in) {
Changli Gao19c9a492010-06-29 13:10:36 +02001396 if (!(in->f_mode & FMODE_PREAD))
Jens Axboeb92ce552006-04-11 13:52:07 +02001397 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001398 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001399 return -EFAULT;
Al Viro7995bd22013-06-20 18:58:36 +04001400 } else {
1401 offset = in->f_pos;
1402 }
Ingo Molnar529565d2006-04-10 15:18:58 +02001403
Al Viro7995bd22013-06-20 18:58:36 +04001404 ret = do_splice_to(in, &offset, opipe, len, flags);
Jens Axboea4514eb2006-04-19 15:57:05 +02001405
Al Viro7995bd22013-06-20 18:58:36 +04001406 if (!off_in)
1407 in->f_pos = offset;
1408 else if (copy_to_user(off_in, &offset, sizeof(loff_t)))
Jens Axboea4514eb2006-04-19 15:57:05 +02001409 ret = -EFAULT;
1410
1411 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001412 }
Jens Axboe5274f052006-03-30 15:15:30 +02001413
1414 return -EINVAL;
1415}
1416
Jens Axboe912d35f2006-04-26 10:59:21 +02001417/*
1418 * Map an iov into an array of pages and offset/length tupples. With the
1419 * partial_page structure, we can map several non-contiguous ranges into
1420 * our ones pages[] map instead of splitting that operation into pieces.
1421 * Could easily be exported as a generic helper for other users, in which
1422 * case one would probably want to add a 'max_nr_pages' parameter as well.
1423 */
1424static int get_iovec_page_array(const struct iovec __user *iov,
1425 unsigned int nr_vecs, struct page **pages,
Eric Dumazetbd1a68b2012-04-04 11:08:51 +02001426 struct partial_page *partial, bool aligned,
Jens Axboe35f3d142010-05-20 10:43:18 +02001427 unsigned int pipe_buffers)
Jens Axboe912d35f2006-04-26 10:59:21 +02001428{
1429 int buffers = 0, error = 0;
1430
Jens Axboe912d35f2006-04-26 10:59:21 +02001431 while (nr_vecs) {
1432 unsigned long off, npages;
Linus Torvalds75723952007-10-01 13:17:28 -07001433 struct iovec entry;
Jens Axboe912d35f2006-04-26 10:59:21 +02001434 void __user *base;
1435 size_t len;
1436 int i;
1437
Linus Torvalds75723952007-10-01 13:17:28 -07001438 error = -EFAULT;
Nick Pigginbc40d732008-07-25 19:45:26 -07001439 if (copy_from_user(&entry, iov, sizeof(entry)))
Jens Axboe912d35f2006-04-26 10:59:21 +02001440 break;
Linus Torvalds75723952007-10-01 13:17:28 -07001441
1442 base = entry.iov_base;
1443 len = entry.iov_len;
Jens Axboe912d35f2006-04-26 10:59:21 +02001444
1445 /*
1446 * Sanity check this iovec. 0 read succeeds.
1447 */
Linus Torvalds75723952007-10-01 13:17:28 -07001448 error = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +02001449 if (unlikely(!len))
1450 break;
1451 error = -EFAULT;
Bastian Blank712a30e2008-02-10 16:47:57 +02001452 if (!access_ok(VERIFY_READ, base, len))
Jens Axboe912d35f2006-04-26 10:59:21 +02001453 break;
1454
1455 /*
1456 * Get this base offset and number of pages, then map
1457 * in the user pages.
1458 */
1459 off = (unsigned long) base & ~PAGE_MASK;
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001460
1461 /*
1462 * If asked for alignment, the offset must be zero and the
1463 * length a multiple of the PAGE_SIZE.
1464 */
1465 error = -EINVAL;
1466 if (aligned && (off || len & ~PAGE_MASK))
1467 break;
1468
Jens Axboe912d35f2006-04-26 10:59:21 +02001469 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
Jens Axboe35f3d142010-05-20 10:43:18 +02001470 if (npages > pipe_buffers - buffers)
1471 npages = pipe_buffers - buffers;
Jens Axboe912d35f2006-04-26 10:59:21 +02001472
Nick Pigginbc40d732008-07-25 19:45:26 -07001473 error = get_user_pages_fast((unsigned long)base, npages,
1474 0, &pages[buffers]);
Jens Axboe912d35f2006-04-26 10:59:21 +02001475
1476 if (unlikely(error <= 0))
1477 break;
1478
1479 /*
1480 * Fill this contiguous range into the partial page map.
1481 */
1482 for (i = 0; i < error; i++) {
Jens Axboe75914892006-05-02 12:57:18 +02001483 const int plen = min_t(size_t, len, PAGE_SIZE - off);
Jens Axboe912d35f2006-04-26 10:59:21 +02001484
1485 partial[buffers].offset = off;
1486 partial[buffers].len = plen;
1487
1488 off = 0;
1489 len -= plen;
1490 buffers++;
1491 }
1492
1493 /*
1494 * We didn't complete this iov, stop here since it probably
1495 * means we have to move some of this into a pipe to
1496 * be able to continue.
1497 */
1498 if (len)
1499 break;
1500
1501 /*
1502 * Don't continue if we mapped fewer pages than we asked for,
1503 * or if we mapped the max number of pages that we have
1504 * room for.
1505 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001506 if (error < npages || buffers == pipe_buffers)
Jens Axboe912d35f2006-04-26 10:59:21 +02001507 break;
1508
1509 nr_vecs--;
1510 iov++;
1511 }
1512
Jens Axboe912d35f2006-04-26 10:59:21 +02001513 if (buffers)
1514 return buffers;
1515
1516 return error;
1517}
1518
Jens Axboe6a14b902007-06-14 13:08:55 +02001519static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1520 struct splice_desc *sd)
1521{
Al Viro6130f532014-02-03 18:19:51 -05001522 int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
1523 return n == sd->len ? n : -EFAULT;
Jens Axboe6a14b902007-06-14 13:08:55 +02001524}
1525
1526/*
1527 * For lack of a better implementation, implement vmsplice() to userspace
1528 * as a simple copy of the pipes pages to the user iov.
1529 */
Al Viro6130f532014-02-03 18:19:51 -05001530static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
Jens Axboe6a14b902007-06-14 13:08:55 +02001531 unsigned long nr_segs, unsigned int flags)
1532{
1533 struct pipe_inode_info *pipe;
1534 struct splice_desc sd;
Jens Axboe6a14b902007-06-14 13:08:55 +02001535 long ret;
Al Viro6130f532014-02-03 18:19:51 -05001536 struct iovec iovstack[UIO_FASTIOV];
1537 struct iovec *iov = iovstack;
1538 struct iov_iter iter;
Jens Axboe6a14b902007-06-14 13:08:55 +02001539
Linus Torvalds71993e62010-11-28 13:56:09 -08001540 pipe = get_pipe_info(file);
Jens Axboe6a14b902007-06-14 13:08:55 +02001541 if (!pipe)
1542 return -EBADF;
1543
Al Viro345995f2015-03-21 19:17:55 -04001544 ret = import_iovec(READ, uiov, nr_segs,
1545 ARRAY_SIZE(iovstack), &iov, &iter);
1546 if (ret < 0)
1547 return ret;
Al Viro6130f532014-02-03 18:19:51 -05001548
Al Viro345995f2015-03-21 19:17:55 -04001549 sd.total_len = iov_iter_count(&iter);
Al Viro6130f532014-02-03 18:19:51 -05001550 sd.len = 0;
Al Viro6130f532014-02-03 18:19:51 -05001551 sd.flags = flags;
1552 sd.u.data = &iter;
1553 sd.pos = 0;
1554
Al Viro345995f2015-03-21 19:17:55 -04001555 if (sd.total_len) {
1556 pipe_lock(pipe);
1557 ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
1558 pipe_unlock(pipe);
1559 }
Jens Axboe6a14b902007-06-14 13:08:55 +02001560
Al Viro345995f2015-03-21 19:17:55 -04001561 kfree(iov);
Jens Axboe6a14b902007-06-14 13:08:55 +02001562 return ret;
1563}
1564
Jens Axboe912d35f2006-04-26 10:59:21 +02001565/*
1566 * vmsplice splices a user address range into a pipe. It can be thought of
1567 * as splice-from-memory, where the regular splice is splice-from-file (or
1568 * to file). In both cases the output is a pipe, naturally.
Jens Axboe912d35f2006-04-26 10:59:21 +02001569 */
Jens Axboe6a14b902007-06-14 13:08:55 +02001570static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
1571 unsigned long nr_segs, unsigned int flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001572{
Jens Axboeddac0d32006-11-04 12:49:32 +01001573 struct pipe_inode_info *pipe;
Jens Axboe35f3d142010-05-20 10:43:18 +02001574 struct page *pages[PIPE_DEF_BUFFERS];
1575 struct partial_page partial[PIPE_DEF_BUFFERS];
Jens Axboe912d35f2006-04-26 10:59:21 +02001576 struct splice_pipe_desc spd = {
1577 .pages = pages,
1578 .partial = partial,
Eric Dumazet047fe362012-06-12 15:24:40 +02001579 .nr_pages_max = PIPE_DEF_BUFFERS,
Jens Axboe912d35f2006-04-26 10:59:21 +02001580 .flags = flags,
1581 .ops = &user_page_pipe_buf_ops,
Jens Axboebbdfc2f2007-11-06 23:29:47 -08001582 .spd_release = spd_release_page,
Jens Axboe912d35f2006-04-26 10:59:21 +02001583 };
Jens Axboe35f3d142010-05-20 10:43:18 +02001584 long ret;
Jens Axboe912d35f2006-04-26 10:59:21 +02001585
Linus Torvalds71993e62010-11-28 13:56:09 -08001586 pipe = get_pipe_info(file);
Jens Axboeddac0d32006-11-04 12:49:32 +01001587 if (!pipe)
Jens Axboe912d35f2006-04-26 10:59:21 +02001588 return -EBADF;
Jens Axboe912d35f2006-04-26 10:59:21 +02001589
Jens Axboe35f3d142010-05-20 10:43:18 +02001590 if (splice_grow_spd(pipe, &spd))
1591 return -ENOMEM;
Jens Axboe912d35f2006-04-26 10:59:21 +02001592
Jens Axboe35f3d142010-05-20 10:43:18 +02001593 spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
Eric Dumazetbd1a68b2012-04-04 11:08:51 +02001594 spd.partial, false,
Eric Dumazet047fe362012-06-12 15:24:40 +02001595 spd.nr_pages_max);
Jens Axboe35f3d142010-05-20 10:43:18 +02001596 if (spd.nr_pages <= 0)
1597 ret = spd.nr_pages;
1598 else
1599 ret = splice_to_pipe(pipe, &spd);
1600
Eric Dumazet047fe362012-06-12 15:24:40 +02001601 splice_shrink_spd(&spd);
Jens Axboe35f3d142010-05-20 10:43:18 +02001602 return ret;
Jens Axboe912d35f2006-04-26 10:59:21 +02001603}
1604
Jens Axboe6a14b902007-06-14 13:08:55 +02001605/*
1606 * Note that vmsplice only really supports true splicing _from_ user memory
1607 * to a pipe, not the other way around. Splicing from user memory is a simple
1608 * operation that can be supported without any funky alignment restrictions
1609 * or nasty vm tricks. We simply map in the user memory and fill them into
1610 * a pipe. The reverse isn't quite as easy, though. There are two possible
1611 * solutions for that:
1612 *
1613 * - memcpy() the data internally, at which point we might as well just
1614 * do a regular read() on the buffer anyway.
1615 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1616 * has restriction limitations on both ends of the pipe).
1617 *
1618 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1619 *
1620 */
Heiko Carstens836f92a2009-01-14 14:14:33 +01001621SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
1622 unsigned long, nr_segs, unsigned int, flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001623{
Al Viro2903ff02012-08-28 12:52:22 -04001624 struct fd f;
Jens Axboe912d35f2006-04-26 10:59:21 +02001625 long error;
Jens Axboe912d35f2006-04-26 10:59:21 +02001626
Jens Axboe6a14b902007-06-14 13:08:55 +02001627 if (unlikely(nr_segs > UIO_MAXIOV))
1628 return -EINVAL;
1629 else if (unlikely(!nr_segs))
1630 return 0;
1631
Jens Axboe912d35f2006-04-26 10:59:21 +02001632 error = -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -04001633 f = fdget(fd);
1634 if (f.file) {
1635 if (f.file->f_mode & FMODE_WRITE)
1636 error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
1637 else if (f.file->f_mode & FMODE_READ)
1638 error = vmsplice_to_user(f.file, iov, nr_segs, flags);
Jens Axboe912d35f2006-04-26 10:59:21 +02001639
Al Viro2903ff02012-08-28 12:52:22 -04001640 fdput(f);
Jens Axboe912d35f2006-04-26 10:59:21 +02001641 }
1642
1643 return error;
1644}
1645
Al Viro76b021d2013-03-02 10:19:56 -05001646#ifdef CONFIG_COMPAT
1647COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
1648 unsigned int, nr_segs, unsigned int, flags)
1649{
1650 unsigned i;
1651 struct iovec __user *iov;
1652 if (nr_segs > UIO_MAXIOV)
1653 return -EINVAL;
1654 iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
1655 for (i = 0; i < nr_segs; i++) {
1656 struct compat_iovec v;
1657 if (get_user(v.iov_base, &iov32[i].iov_base) ||
1658 get_user(v.iov_len, &iov32[i].iov_len) ||
1659 put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
1660 put_user(v.iov_len, &iov[i].iov_len))
1661 return -EFAULT;
1662 }
1663 return sys_vmsplice(fd, iov, nr_segs, flags);
1664}
1665#endif
1666
Heiko Carstens836f92a2009-01-14 14:14:33 +01001667SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1668 int, fd_out, loff_t __user *, off_out,
1669 size_t, len, unsigned int, flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001670{
Al Viro2903ff02012-08-28 12:52:22 -04001671 struct fd in, out;
Jens Axboe5274f052006-03-30 15:15:30 +02001672 long error;
Jens Axboe5274f052006-03-30 15:15:30 +02001673
1674 if (unlikely(!len))
1675 return 0;
1676
1677 error = -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -04001678 in = fdget(fd_in);
1679 if (in.file) {
1680 if (in.file->f_mode & FMODE_READ) {
1681 out = fdget(fd_out);
1682 if (out.file) {
1683 if (out.file->f_mode & FMODE_WRITE)
1684 error = do_splice(in.file, off_in,
1685 out.file, off_out,
Ingo Molnar529565d2006-04-10 15:18:58 +02001686 len, flags);
Al Viro2903ff02012-08-28 12:52:22 -04001687 fdput(out);
Jens Axboe5274f052006-03-30 15:15:30 +02001688 }
1689 }
Al Viro2903ff02012-08-28 12:52:22 -04001690 fdput(in);
Jens Axboe5274f052006-03-30 15:15:30 +02001691 }
Jens Axboe5274f052006-03-30 15:15:30 +02001692 return error;
1693}
Jens Axboe70524492006-04-11 15:51:17 +02001694
1695/*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001696 * Make sure there's data to read. Wait for input if we can, otherwise
1697 * return an appropriate error.
1698 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001699static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001700{
1701 int ret;
1702
1703 /*
1704 * Check ->nrbufs without the inode lock first. This function
1705 * is speculative anyways, so missing one is ok.
1706 */
1707 if (pipe->nrbufs)
1708 return 0;
1709
1710 ret = 0;
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001711 pipe_lock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001712
1713 while (!pipe->nrbufs) {
1714 if (signal_pending(current)) {
1715 ret = -ERESTARTSYS;
1716 break;
1717 }
1718 if (!pipe->writers)
1719 break;
1720 if (!pipe->waiting_writers) {
1721 if (flags & SPLICE_F_NONBLOCK) {
1722 ret = -EAGAIN;
1723 break;
1724 }
1725 }
1726 pipe_wait(pipe);
1727 }
1728
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001729 pipe_unlock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001730 return ret;
1731}
1732
1733/*
1734 * Make sure there's writeable room. Wait for room if we can, otherwise
1735 * return an appropriate error.
1736 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001737static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001738{
1739 int ret;
1740
1741 /*
1742 * Check ->nrbufs without the inode lock first. This function
1743 * is speculative anyways, so missing one is ok.
1744 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001745 if (pipe->nrbufs < pipe->buffers)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001746 return 0;
1747
1748 ret = 0;
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001749 pipe_lock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001750
Jens Axboe35f3d142010-05-20 10:43:18 +02001751 while (pipe->nrbufs >= pipe->buffers) {
Jens Axboeaadd06e2006-07-10 11:00:01 +02001752 if (!pipe->readers) {
1753 send_sig(SIGPIPE, current, 0);
1754 ret = -EPIPE;
1755 break;
1756 }
1757 if (flags & SPLICE_F_NONBLOCK) {
1758 ret = -EAGAIN;
1759 break;
1760 }
1761 if (signal_pending(current)) {
1762 ret = -ERESTARTSYS;
1763 break;
1764 }
1765 pipe->waiting_writers++;
1766 pipe_wait(pipe);
1767 pipe->waiting_writers--;
1768 }
1769
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001770 pipe_unlock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001771 return ret;
1772}
1773
1774/*
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001775 * Splice contents of ipipe to opipe.
1776 */
1777static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1778 struct pipe_inode_info *opipe,
1779 size_t len, unsigned int flags)
1780{
1781 struct pipe_buffer *ibuf, *obuf;
1782 int ret = 0, nbuf;
1783 bool input_wakeup = false;
1784
1785
1786retry:
1787 ret = ipipe_prep(ipipe, flags);
1788 if (ret)
1789 return ret;
1790
1791 ret = opipe_prep(opipe, flags);
1792 if (ret)
1793 return ret;
1794
1795 /*
1796 * Potential ABBA deadlock, work around it by ordering lock
1797 * grabbing by pipe info address. Otherwise two different processes
1798 * could deadlock (one doing tee from A -> B, the other from B -> A).
1799 */
1800 pipe_double_lock(ipipe, opipe);
1801
1802 do {
1803 if (!opipe->readers) {
1804 send_sig(SIGPIPE, current, 0);
1805 if (!ret)
1806 ret = -EPIPE;
1807 break;
1808 }
1809
1810 if (!ipipe->nrbufs && !ipipe->writers)
1811 break;
1812
1813 /*
1814 * Cannot make any progress, because either the input
1815 * pipe is empty or the output pipe is full.
1816 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001817 if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001818 /* Already processed some buffers, break */
1819 if (ret)
1820 break;
1821
1822 if (flags & SPLICE_F_NONBLOCK) {
1823 ret = -EAGAIN;
1824 break;
1825 }
1826
1827 /*
1828 * We raced with another reader/writer and haven't
1829 * managed to process any buffers. A zero return
1830 * value means EOF, so retry instead.
1831 */
1832 pipe_unlock(ipipe);
1833 pipe_unlock(opipe);
1834 goto retry;
1835 }
1836
1837 ibuf = ipipe->bufs + ipipe->curbuf;
Jens Axboe35f3d142010-05-20 10:43:18 +02001838 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001839 obuf = opipe->bufs + nbuf;
1840
1841 if (len >= ibuf->len) {
1842 /*
1843 * Simply move the whole buffer from ipipe to opipe
1844 */
1845 *obuf = *ibuf;
1846 ibuf->ops = NULL;
1847 opipe->nrbufs++;
Jens Axboe35f3d142010-05-20 10:43:18 +02001848 ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001849 ipipe->nrbufs--;
1850 input_wakeup = true;
1851 } else {
1852 /*
1853 * Get a reference to this pipe buffer,
1854 * so we can copy the contents over.
1855 */
1856 ibuf->ops->get(ipipe, ibuf);
1857 *obuf = *ibuf;
1858
1859 /*
1860 * Don't inherit the gift flag, we need to
1861 * prevent multiple steals of this page.
1862 */
1863 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1864
1865 obuf->len = len;
1866 opipe->nrbufs++;
1867 ibuf->offset += obuf->len;
1868 ibuf->len -= obuf->len;
1869 }
1870 ret += obuf->len;
1871 len -= obuf->len;
1872 } while (len);
1873
1874 pipe_unlock(ipipe);
1875 pipe_unlock(opipe);
1876
1877 /*
1878 * If we put data in the output pipe, wakeup any potential readers.
1879 */
Namhyung Kim825cdcb2011-05-23 19:58:53 +02001880 if (ret > 0)
1881 wakeup_pipe_readers(opipe);
1882
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001883 if (input_wakeup)
1884 wakeup_pipe_writers(ipipe);
1885
1886 return ret;
1887}
1888
1889/*
Jens Axboe70524492006-04-11 15:51:17 +02001890 * Link contents of ipipe to opipe.
1891 */
1892static int link_pipe(struct pipe_inode_info *ipipe,
1893 struct pipe_inode_info *opipe,
1894 size_t len, unsigned int flags)
1895{
1896 struct pipe_buffer *ibuf, *obuf;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001897 int ret = 0, i = 0, nbuf;
Jens Axboe70524492006-04-11 15:51:17 +02001898
1899 /*
1900 * Potential ABBA deadlock, work around it by ordering lock
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001901 * grabbing by pipe info address. Otherwise two different processes
Jens Axboe70524492006-04-11 15:51:17 +02001902 * could deadlock (one doing tee from A -> B, the other from B -> A).
1903 */
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001904 pipe_double_lock(ipipe, opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001905
Jens Axboeaadd06e2006-07-10 11:00:01 +02001906 do {
Jens Axboe70524492006-04-11 15:51:17 +02001907 if (!opipe->readers) {
1908 send_sig(SIGPIPE, current, 0);
1909 if (!ret)
1910 ret = -EPIPE;
1911 break;
1912 }
Jens Axboe70524492006-04-11 15:51:17 +02001913
1914 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001915 * If we have iterated all input buffers or ran out of
1916 * output room, break.
Jens Axboe70524492006-04-11 15:51:17 +02001917 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001918 if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
Jens Axboe70524492006-04-11 15:51:17 +02001919 break;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001920
Jens Axboe35f3d142010-05-20 10:43:18 +02001921 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
1922 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001923
Jens Axboe2a27250e2006-04-19 15:56:40 +02001924 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001925 * Get a reference to this pipe buffer,
1926 * so we can copy the contents over.
Jens Axboe2a27250e2006-04-19 15:56:40 +02001927 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001928 ibuf->ops->get(ipipe, ibuf);
Jens Axboe70524492006-04-11 15:51:17 +02001929
Jens Axboeaadd06e2006-07-10 11:00:01 +02001930 obuf = opipe->bufs + nbuf;
1931 *obuf = *ibuf;
Jens Axboe70524492006-04-11 15:51:17 +02001932
Jens Axboeaadd06e2006-07-10 11:00:01 +02001933 /*
1934 * Don't inherit the gift flag, we need to
1935 * prevent multiple steals of this page.
1936 */
1937 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1938
1939 if (obuf->len > len)
1940 obuf->len = len;
1941
1942 opipe->nrbufs++;
1943 ret += obuf->len;
1944 len -= obuf->len;
1945 i++;
1946 } while (len);
Jens Axboe70524492006-04-11 15:51:17 +02001947
Jens Axboe02cf01a2008-02-20 10:34:51 +01001948 /*
1949 * return EAGAIN if we have the potential of some data in the
1950 * future, otherwise just return 0
1951 */
1952 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1953 ret = -EAGAIN;
1954
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001955 pipe_unlock(ipipe);
1956 pipe_unlock(opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001957
Jens Axboeaadd06e2006-07-10 11:00:01 +02001958 /*
1959 * If we put data in the output pipe, wakeup any potential readers.
1960 */
Namhyung Kim825cdcb2011-05-23 19:58:53 +02001961 if (ret > 0)
1962 wakeup_pipe_readers(opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001963
1964 return ret;
1965}
1966
1967/*
1968 * This is a tee(1) implementation that works on pipes. It doesn't copy
1969 * any data, it simply references the 'in' pages on the 'out' pipe.
1970 * The 'flags' used are the SPLICE_F_* variants, currently the only
1971 * applicable one is SPLICE_F_NONBLOCK.
1972 */
1973static long do_tee(struct file *in, struct file *out, size_t len,
1974 unsigned int flags)
1975{
Linus Torvalds71993e62010-11-28 13:56:09 -08001976 struct pipe_inode_info *ipipe = get_pipe_info(in);
1977 struct pipe_inode_info *opipe = get_pipe_info(out);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001978 int ret = -EINVAL;
Jens Axboe70524492006-04-11 15:51:17 +02001979
1980 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001981 * Duplicate the contents of ipipe to opipe without actually
1982 * copying the data.
Jens Axboe70524492006-04-11 15:51:17 +02001983 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001984 if (ipipe && opipe && ipipe != opipe) {
1985 /*
1986 * Keep going, unless we encounter an error. The ipipe/opipe
1987 * ordering doesn't really matter.
1988 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001989 ret = ipipe_prep(ipipe, flags);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001990 if (!ret) {
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001991 ret = opipe_prep(opipe, flags);
Jens Axboe02cf01a2008-02-20 10:34:51 +01001992 if (!ret)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001993 ret = link_pipe(ipipe, opipe, len, flags);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001994 }
1995 }
Jens Axboe70524492006-04-11 15:51:17 +02001996
Jens Axboeaadd06e2006-07-10 11:00:01 +02001997 return ret;
Jens Axboe70524492006-04-11 15:51:17 +02001998}
1999
Heiko Carstens836f92a2009-01-14 14:14:33 +01002000SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
Jens Axboe70524492006-04-11 15:51:17 +02002001{
Al Viro2903ff02012-08-28 12:52:22 -04002002 struct fd in;
2003 int error;
Jens Axboe70524492006-04-11 15:51:17 +02002004
2005 if (unlikely(!len))
2006 return 0;
2007
2008 error = -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -04002009 in = fdget(fdin);
2010 if (in.file) {
2011 if (in.file->f_mode & FMODE_READ) {
2012 struct fd out = fdget(fdout);
2013 if (out.file) {
2014 if (out.file->f_mode & FMODE_WRITE)
2015 error = do_tee(in.file, out.file,
2016 len, flags);
2017 fdput(out);
Jens Axboe70524492006-04-11 15:51:17 +02002018 }
2019 }
Al Viro2903ff02012-08-28 12:52:22 -04002020 fdput(in);
Jens Axboe70524492006-04-11 15:51:17 +02002021 }
2022
2023 return error;
2024}