blob: 4cf700d50b4037e6c334b0647cdb81b816f9ef65 [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}
Hannes Frederic Sowa2b514572015-05-21 17:00:01 +0200264EXPORT_SYMBOL_GPL(splice_to_pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200265
Hugh Dickins708e3502011-07-25 17:12:32 -0700266void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800267{
268 page_cache_release(spd->pages[i]);
269}
270
Jens Axboe35f3d142010-05-20 10:43:18 +0200271/*
272 * Check if we need to grow the arrays holding pages and partial page
273 * descriptions.
274 */
Eric Dumazet047fe362012-06-12 15:24:40 +0200275int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
Jens Axboe35f3d142010-05-20 10:43:18 +0200276{
Eric Dumazet047fe362012-06-12 15:24:40 +0200277 unsigned int buffers = ACCESS_ONCE(pipe->buffers);
278
279 spd->nr_pages_max = buffers;
280 if (buffers <= PIPE_DEF_BUFFERS)
Jens Axboe35f3d142010-05-20 10:43:18 +0200281 return 0;
282
Eric Dumazet047fe362012-06-12 15:24:40 +0200283 spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
284 spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
Jens Axboe35f3d142010-05-20 10:43:18 +0200285
286 if (spd->pages && spd->partial)
287 return 0;
288
289 kfree(spd->pages);
290 kfree(spd->partial);
291 return -ENOMEM;
292}
293
Eric Dumazet047fe362012-06-12 15:24:40 +0200294void splice_shrink_spd(struct splice_pipe_desc *spd)
Jens Axboe35f3d142010-05-20 10:43:18 +0200295{
Eric Dumazet047fe362012-06-12 15:24:40 +0200296 if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
Jens Axboe35f3d142010-05-20 10:43:18 +0200297 return;
298
299 kfree(spd->pages);
300 kfree(spd->partial);
301}
302
Ingo Molnar3a326a22006-04-10 15:18:35 +0200303static int
Jens Axboecbb7e572006-04-11 14:57:50 +0200304__generic_file_splice_read(struct file *in, loff_t *ppos,
305 struct pipe_inode_info *pipe, size_t len,
306 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200307{
308 struct address_space *mapping = in->f_mapping;
Fengguang Wud8983912007-07-19 01:48:06 -0700309 unsigned int loff, nr_pages, req_pages;
Jens Axboe35f3d142010-05-20 10:43:18 +0200310 struct page *pages[PIPE_DEF_BUFFERS];
311 struct partial_page partial[PIPE_DEF_BUFFERS];
Jens Axboe5274f052006-03-30 15:15:30 +0200312 struct page *page;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200313 pgoff_t index, end_index;
314 loff_t isize;
Jens Axboeeb207962006-04-27 11:05:22 +0200315 int error, page_nr;
Jens Axboe912d35f2006-04-26 10:59:21 +0200316 struct splice_pipe_desc spd = {
317 .pages = pages,
318 .partial = partial,
Eric Dumazet047fe362012-06-12 15:24:40 +0200319 .nr_pages_max = PIPE_DEF_BUFFERS,
Jens Axboe912d35f2006-04-26 10:59:21 +0200320 .flags = flags,
321 .ops = &page_cache_pipe_buf_ops,
Jens Axboebbdfc2f2007-11-06 23:29:47 -0800322 .spd_release = spd_release_page,
Jens Axboe912d35f2006-04-26 10:59:21 +0200323 };
Jens Axboe5274f052006-03-30 15:15:30 +0200324
Jens Axboe35f3d142010-05-20 10:43:18 +0200325 if (splice_grow_spd(pipe, &spd))
326 return -ENOMEM;
327
Jens Axboecbb7e572006-04-11 14:57:50 +0200328 index = *ppos >> PAGE_CACHE_SHIFT;
Jens Axboe912d35f2006-04-26 10:59:21 +0200329 loff = *ppos & ~PAGE_CACHE_MASK;
Fengguang Wud8983912007-07-19 01:48:06 -0700330 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Eric Dumazet047fe362012-06-12 15:24:40 +0200331 nr_pages = min(req_pages, spd.nr_pages_max);
Jens Axboe5274f052006-03-30 15:15:30 +0200332
333 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200334 * Lookup the (hopefully) full range of pages we need.
335 */
Jens Axboe35f3d142010-05-20 10:43:18 +0200336 spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages);
Fengguang Wu431a48202007-07-19 01:48:05 -0700337 index += spd.nr_pages;
Jens Axboeeb207962006-04-27 11:05:22 +0200338
339 /*
340 * If find_get_pages_contig() returned fewer pages than we needed,
Fengguang Wu431a48202007-07-19 01:48:05 -0700341 * readahead/allocate the rest and fill in the holes.
Jens Axboeeb207962006-04-27 11:05:22 +0200342 */
Fengguang Wu431a48202007-07-19 01:48:05 -0700343 if (spd.nr_pages < nr_pages)
Rusty Russellcf914a72007-07-19 01:48:08 -0700344 page_cache_sync_readahead(mapping, &in->f_ra, in,
345 index, req_pages - spd.nr_pages);
Fengguang Wu431a48202007-07-19 01:48:05 -0700346
Jens Axboe932cc6d2007-06-21 13:10:21 +0200347 error = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200348 while (spd.nr_pages < nr_pages) {
349 /*
350 * Page could be there, find_get_pages_contig() breaks on
351 * the first hole.
352 */
353 page = find_get_page(mapping, index);
354 if (!page) {
Jens Axboee27dedd2006-05-01 19:59:54 +0200355 /*
Jens Axboeeb207962006-04-27 11:05:22 +0200356 * page didn't exist, allocate one.
357 */
358 page = page_cache_alloc_cold(mapping);
359 if (!page)
360 break;
361
362 error = add_to_page_cache_lru(page, mapping, index,
Michal Hockoc62d2552015-11-06 16:28:49 -0800363 mapping_gfp_constraint(mapping, GFP_KERNEL));
Jens Axboeeb207962006-04-27 11:05:22 +0200364 if (unlikely(error)) {
365 page_cache_release(page);
Jens Axboea0548872006-05-03 10:58:22 +0200366 if (error == -EEXIST)
367 continue;
Jens Axboeeb207962006-04-27 11:05:22 +0200368 break;
369 }
370 /*
371 * add_to_page_cache() locks the page, unlock it
372 * to avoid convoluting the logic below even more.
373 */
374 unlock_page(page);
375 }
376
Jens Axboe35f3d142010-05-20 10:43:18 +0200377 spd.pages[spd.nr_pages++] = page;
Jens Axboeeb207962006-04-27 11:05:22 +0200378 index++;
379 }
380
381 /*
382 * Now loop over the map and see if we need to start IO on any
383 * pages, fill in the partial map, etc.
384 */
385 index = *ppos >> PAGE_CACHE_SHIFT;
386 nr_pages = spd.nr_pages;
387 spd.nr_pages = 0;
388 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
Jens Axboe82aa5d62006-04-20 13:05:48 +0200389 unsigned int this_len;
390
391 if (!len)
392 break;
393
394 /*
395 * this_len is the max we'll use from this page
396 */
Andrew Mortonba5f5d92006-04-25 15:33:34 +0200397 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
Jens Axboe35f3d142010-05-20 10:43:18 +0200398 page = spd.pages[page_nr];
Jens Axboe7480a902006-04-11 13:52:47 +0200399
Fengguang Wua08a1662007-07-19 01:48:03 -0700400 if (PageReadahead(page))
Rusty Russellcf914a72007-07-19 01:48:08 -0700401 page_cache_async_readahead(mapping, &in->f_ra, in,
Fengguang Wud8983912007-07-19 01:48:06 -0700402 page, index, req_pages - page_nr);
Fengguang Wua08a1662007-07-19 01:48:03 -0700403
Jens Axboe7480a902006-04-11 13:52:47 +0200404 /*
405 * If the page isn't uptodate, we may need to start io on it
406 */
407 if (!PageUptodate(page)) {
Miklos Szeredi69650312010-08-03 12:48:50 +0200408 lock_page(page);
Jens Axboe7480a902006-04-11 13:52:47 +0200409
410 /*
Miklos Szeredi32502b82008-07-04 09:35:17 +0200411 * Page was truncated, or invalidated by the
412 * filesystem. Redo the find/create, but this time the
413 * page is kept locked, so there's no chance of another
414 * race with truncate/invalidate.
Jens Axboe7480a902006-04-11 13:52:47 +0200415 */
416 if (!page->mapping) {
417 unlock_page(page);
Miklos Szeredi32502b82008-07-04 09:35:17 +0200418 page = find_or_create_page(mapping, index,
419 mapping_gfp_mask(mapping));
420
421 if (!page) {
422 error = -ENOMEM;
423 break;
424 }
Jens Axboe35f3d142010-05-20 10:43:18 +0200425 page_cache_release(spd.pages[page_nr]);
426 spd.pages[page_nr] = page;
Jens Axboe7480a902006-04-11 13:52:47 +0200427 }
428 /*
429 * page was already under io and is now done, great
430 */
431 if (PageUptodate(page)) {
432 unlock_page(page);
433 goto fill_it;
434 }
435
Jens Axboe7480a902006-04-11 13:52:47 +0200436 /*
437 * need to read in the page
438 */
439 error = mapping->a_ops->readpage(in, page);
Jens Axboe7480a902006-04-11 13:52:47 +0200440 if (unlikely(error)) {
Jens Axboeeb207962006-04-27 11:05:22 +0200441 /*
442 * We really should re-lookup the page here,
443 * but it complicates things a lot. Instead
444 * lets just do what we already stored, and
445 * we'll get it the next time we are called.
446 */
Jens Axboe7480a902006-04-11 13:52:47 +0200447 if (error == AOP_TRUNCATED_PAGE)
Jens Axboeeb207962006-04-27 11:05:22 +0200448 error = 0;
449
Jens Axboe7480a902006-04-11 13:52:47 +0200450 break;
451 }
Jens Axboe620a3242007-06-07 09:39:42 +0200452 }
453fill_it:
454 /*
455 * i_size must be checked after PageUptodate.
456 */
457 isize = i_size_read(mapping->host);
458 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
459 if (unlikely(!isize || index > end_index))
460 break;
461
462 /*
463 * if this is the last page, see if we need to shrink
464 * the length and stop
465 */
466 if (end_index == index) {
467 unsigned int plen;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200468
469 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200470 * max good bytes in this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200471 */
Jens Axboe620a3242007-06-07 09:39:42 +0200472 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
473 if (plen <= loff)
Jens Axboe91ad66e2006-04-19 15:55:10 +0200474 break;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200475
476 /*
Jens Axboe620a3242007-06-07 09:39:42 +0200477 * force quit after adding this page
Jens Axboe91ad66e2006-04-19 15:55:10 +0200478 */
Jens Axboe620a3242007-06-07 09:39:42 +0200479 this_len = min(this_len, plen - loff);
480 len = this_len;
Jens Axboe7480a902006-04-11 13:52:47 +0200481 }
Jens Axboe620a3242007-06-07 09:39:42 +0200482
Jens Axboe35f3d142010-05-20 10:43:18 +0200483 spd.partial[page_nr].offset = loff;
484 spd.partial[page_nr].len = this_len;
Jens Axboe82aa5d62006-04-20 13:05:48 +0200485 len -= this_len;
Jens Axboe91ad66e2006-04-19 15:55:10 +0200486 loff = 0;
Jens Axboeeb207962006-04-27 11:05:22 +0200487 spd.nr_pages++;
488 index++;
Jens Axboe5274f052006-03-30 15:15:30 +0200489 }
490
Jens Axboeeb207962006-04-27 11:05:22 +0200491 /*
Hugh Dickins475ecad2007-06-07 09:36:00 +0200492 * Release any pages at the end, if we quit early. 'page_nr' is how far
Jens Axboeeb207962006-04-27 11:05:22 +0200493 * we got, 'nr_pages' is how many pages are in the map.
494 */
495 while (page_nr < nr_pages)
Jens Axboe35f3d142010-05-20 10:43:18 +0200496 page_cache_release(spd.pages[page_nr++]);
Fengguang Wuf4e6b492007-10-16 01:24:33 -0700497 in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
Jens Axboeeb207962006-04-27 11:05:22 +0200498
Jens Axboe912d35f2006-04-26 10:59:21 +0200499 if (spd.nr_pages)
Jens Axboe35f3d142010-05-20 10:43:18 +0200500 error = splice_to_pipe(pipe, &spd);
Jens Axboe5274f052006-03-30 15:15:30 +0200501
Eric Dumazet047fe362012-06-12 15:24:40 +0200502 splice_shrink_spd(&spd);
Jens Axboe7480a902006-04-11 13:52:47 +0200503 return error;
Jens Axboe5274f052006-03-30 15:15:30 +0200504}
505
Jens Axboe83f91352006-04-02 23:05:09 +0200506/**
507 * generic_file_splice_read - splice data from file to a pipe
508 * @in: file to splice from
Jens Axboe932cc6d2007-06-21 13:10:21 +0200509 * @ppos: position in @in
Jens Axboe83f91352006-04-02 23:05:09 +0200510 * @pipe: pipe to splice to
511 * @len: number of bytes to splice
512 * @flags: splice modifier flags
513 *
Jens Axboe932cc6d2007-06-21 13:10:21 +0200514 * Description:
515 * Will read pages from given file and fill them into a pipe. Can be
516 * used as long as the address_space operations for the source implements
517 * a readpage() hook.
518 *
Jens Axboe83f91352006-04-02 23:05:09 +0200519 */
Jens Axboecbb7e572006-04-11 14:57:50 +0200520ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
521 struct pipe_inode_info *pipe, size_t len,
522 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +0200523{
Jens Axboed366d3982007-06-01 14:54:11 +0200524 loff_t isize, left;
Jens Axboe8191ecd2008-04-10 08:24:25 +0200525 int ret;
Jens Axboed366d3982007-06-01 14:54:11 +0200526
Boaz Harroshbe64f882015-04-15 16:15:17 -0700527 if (IS_DAX(in->f_mapping->host))
528 return default_file_splice_read(in, ppos, pipe, len, flags);
529
Jens Axboed366d3982007-06-01 14:54:11 +0200530 isize = i_size_read(in->f_mapping->host);
531 if (unlikely(*ppos >= isize))
532 return 0;
533
534 left = isize - *ppos;
535 if (unlikely(left < len))
536 len = left;
Jens Axboe5274f052006-03-30 15:15:30 +0200537
Jens Axboe8191ecd2008-04-10 08:24:25 +0200538 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
Miklos Szeredi723590e2009-08-15 08:43:22 +0200539 if (ret > 0) {
Jens Axboecbb7e572006-04-11 14:57:50 +0200540 *ppos += ret;
Miklos Szeredi723590e2009-08-15 08:43:22 +0200541 file_accessed(in);
542 }
Jens Axboe5274f052006-03-30 15:15:30 +0200543
544 return ret;
545}
Jens Axboe059a8f32006-04-02 23:06:05 +0200546EXPORT_SYMBOL(generic_file_splice_read);
547
Miklos Szeredi68181732009-05-07 15:37:36 +0200548static const struct pipe_buf_operations default_pipe_buf_ops = {
549 .can_merge = 0,
Miklos Szeredi68181732009-05-07 15:37:36 +0200550 .confirm = generic_pipe_buf_confirm,
551 .release = generic_pipe_buf_release,
552 .steal = generic_pipe_buf_steal,
553 .get = generic_pipe_buf_get,
554};
555
Miklos Szeredi28a625c2014-01-22 19:36:57 +0100556static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
557 struct pipe_buffer *buf)
558{
559 return 1;
560}
561
562/* Pipe buffer operations for a socket and similar. */
563const struct pipe_buf_operations nosteal_pipe_buf_ops = {
564 .can_merge = 0,
Miklos Szeredi28a625c2014-01-22 19:36:57 +0100565 .confirm = generic_pipe_buf_confirm,
566 .release = generic_pipe_buf_release,
567 .steal = generic_pipe_buf_nosteal,
568 .get = generic_pipe_buf_get,
569};
570EXPORT_SYMBOL(nosteal_pipe_buf_ops);
571
Miklos Szeredi68181732009-05-07 15:37:36 +0200572static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
573 unsigned long vlen, loff_t offset)
574{
575 mm_segment_t old_fs;
576 loff_t pos = offset;
577 ssize_t res;
578
579 old_fs = get_fs();
580 set_fs(get_ds());
581 /* The cast to a user pointer is valid due to the set_fs() */
582 res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos);
583 set_fs(old_fs);
584
585 return res;
586}
587
Al Viro7bb307e2013-02-23 14:51:48 -0500588ssize_t kernel_write(struct file *file, const char *buf, size_t count,
Miklos Szeredib2858d72009-05-19 11:37:46 +0200589 loff_t pos)
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200590{
591 mm_segment_t old_fs;
592 ssize_t res;
593
594 old_fs = get_fs();
595 set_fs(get_ds());
596 /* The cast to a user pointer is valid due to the set_fs() */
Al Viro7bb307e2013-02-23 14:51:48 -0500597 res = vfs_write(file, (__force const char __user *)buf, count, &pos);
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200598 set_fs(old_fs);
599
600 return res;
601}
Al Viro7bb307e2013-02-23 14:51:48 -0500602EXPORT_SYMBOL(kernel_write);
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +0200603
Miklos Szeredi68181732009-05-07 15:37:36 +0200604ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
605 struct pipe_inode_info *pipe, size_t len,
606 unsigned int flags)
607{
608 unsigned int nr_pages;
609 unsigned int nr_freed;
610 size_t offset;
Jens Axboe35f3d142010-05-20 10:43:18 +0200611 struct page *pages[PIPE_DEF_BUFFERS];
612 struct partial_page partial[PIPE_DEF_BUFFERS];
613 struct iovec *vec, __vec[PIPE_DEF_BUFFERS];
Miklos Szeredi68181732009-05-07 15:37:36 +0200614 ssize_t res;
615 size_t this_len;
616 int error;
617 int i;
618 struct splice_pipe_desc spd = {
619 .pages = pages,
620 .partial = partial,
Eric Dumazet047fe362012-06-12 15:24:40 +0200621 .nr_pages_max = PIPE_DEF_BUFFERS,
Miklos Szeredi68181732009-05-07 15:37:36 +0200622 .flags = flags,
623 .ops = &default_pipe_buf_ops,
624 .spd_release = spd_release_page,
625 };
626
Jens Axboe35f3d142010-05-20 10:43:18 +0200627 if (splice_grow_spd(pipe, &spd))
628 return -ENOMEM;
629
630 res = -ENOMEM;
631 vec = __vec;
Eric Dumazet047fe362012-06-12 15:24:40 +0200632 if (spd.nr_pages_max > PIPE_DEF_BUFFERS) {
633 vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL);
Jens Axboe35f3d142010-05-20 10:43:18 +0200634 if (!vec)
635 goto shrink_ret;
636 }
637
Miklos Szeredi68181732009-05-07 15:37:36 +0200638 offset = *ppos & ~PAGE_CACHE_MASK;
639 nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
640
Eric Dumazet047fe362012-06-12 15:24:40 +0200641 for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) {
Miklos Szeredi68181732009-05-07 15:37:36 +0200642 struct page *page;
643
Jens Axboe4f231222009-05-13 08:35:35 +0200644 page = alloc_page(GFP_USER);
Miklos Szeredi68181732009-05-07 15:37:36 +0200645 error = -ENOMEM;
646 if (!page)
647 goto err;
648
649 this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset);
Jens Axboe4f231222009-05-13 08:35:35 +0200650 vec[i].iov_base = (void __user *) page_address(page);
Miklos Szeredi68181732009-05-07 15:37:36 +0200651 vec[i].iov_len = this_len;
Jens Axboe35f3d142010-05-20 10:43:18 +0200652 spd.pages[i] = page;
Miklos Szeredi68181732009-05-07 15:37:36 +0200653 spd.nr_pages++;
654 len -= this_len;
655 offset = 0;
656 }
657
658 res = kernel_readv(in, vec, spd.nr_pages, *ppos);
Andrew Morton77f6bf52009-05-14 09:49:44 +0200659 if (res < 0) {
660 error = res;
Miklos Szeredi68181732009-05-07 15:37:36 +0200661 goto err;
Andrew Morton77f6bf52009-05-14 09:49:44 +0200662 }
Miklos Szeredi68181732009-05-07 15:37:36 +0200663
664 error = 0;
665 if (!res)
666 goto err;
667
668 nr_freed = 0;
669 for (i = 0; i < spd.nr_pages; i++) {
Miklos Szeredi68181732009-05-07 15:37:36 +0200670 this_len = min_t(size_t, vec[i].iov_len, res);
Jens Axboe35f3d142010-05-20 10:43:18 +0200671 spd.partial[i].offset = 0;
672 spd.partial[i].len = this_len;
Miklos Szeredi68181732009-05-07 15:37:36 +0200673 if (!this_len) {
Jens Axboe35f3d142010-05-20 10:43:18 +0200674 __free_page(spd.pages[i]);
675 spd.pages[i] = NULL;
Miklos Szeredi68181732009-05-07 15:37:36 +0200676 nr_freed++;
677 }
678 res -= this_len;
679 }
680 spd.nr_pages -= nr_freed;
681
682 res = splice_to_pipe(pipe, &spd);
683 if (res > 0)
684 *ppos += res;
685
Jens Axboe35f3d142010-05-20 10:43:18 +0200686shrink_ret:
687 if (vec != __vec)
688 kfree(vec);
Eric Dumazet047fe362012-06-12 15:24:40 +0200689 splice_shrink_spd(&spd);
Miklos Szeredi68181732009-05-07 15:37:36 +0200690 return res;
691
692err:
Jens Axboe4f231222009-05-13 08:35:35 +0200693 for (i = 0; i < spd.nr_pages; i++)
Jens Axboe35f3d142010-05-20 10:43:18 +0200694 __free_page(spd.pages[i]);
Jens Axboe4f231222009-05-13 08:35:35 +0200695
Jens Axboe35f3d142010-05-20 10:43:18 +0200696 res = error;
697 goto shrink_ret;
Miklos Szeredi68181732009-05-07 15:37:36 +0200698}
699EXPORT_SYMBOL(default_file_splice_read);
700
Jens Axboe5274f052006-03-30 15:15:30 +0200701/*
Jens Axboe4f6f0bd2006-04-02 23:04:46 +0200702 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
Jens Axboe016b6612006-04-25 15:42:00 +0200703 * using sendpage(). Return the number of bytes sent.
Jens Axboe5274f052006-03-30 15:15:30 +0200704 */
Jens Axboe76ad4d12006-05-03 10:41:33 +0200705static int pipe_to_sendpage(struct pipe_inode_info *pipe,
Jens Axboe5274f052006-03-30 15:15:30 +0200706 struct pipe_buffer *buf, struct splice_desc *sd)
707{
Jens Axboe6a14b902007-06-14 13:08:55 +0200708 struct file *file = sd->u.file;
Jens Axboe5274f052006-03-30 15:15:30 +0200709 loff_t pos = sd->pos;
Michał Mirosława8adbe32010-12-17 08:56:44 +0100710 int more;
Jens Axboe5274f052006-03-30 15:15:30 +0200711
Al Viro72c2d532013-09-22 16:27:52 -0400712 if (!likely(file->f_op->sendpage))
Michał Mirosława8adbe32010-12-17 08:56:44 +0100713 return -EINVAL;
Jens Axboe5274f052006-03-30 15:15:30 +0200714
Eric Dumazet35f9c092012-04-05 03:05:35 +0000715 more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
Eric Dumazetae62ca72013-01-06 18:21:49 +0000716
717 if (sd->len < sd->total_len && pipe->nrbufs > 1)
Eric Dumazet35f9c092012-04-05 03:05:35 +0000718 more |= MSG_SENDPAGE_NOTLAST;
Eric Dumazetae62ca72013-01-06 18:21:49 +0000719
Michał Mirosława8adbe32010-12-17 08:56:44 +0100720 return file->f_op->sendpage(file, buf->page, buf->offset,
721 sd->len, &pos, more);
Jens Axboe5274f052006-03-30 15:15:30 +0200722}
723
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200724static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
725{
726 smp_mb();
727 if (waitqueue_active(&pipe->wait))
728 wake_up_interruptible(&pipe->wait);
729 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
730}
731
732/**
733 * splice_from_pipe_feed - feed available data from a pipe to a file
734 * @pipe: pipe to splice from
735 * @sd: information to @actor
736 * @actor: handler that splices the data
737 *
738 * Description:
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200739 * This function loops over the pipe and calls @actor to do the
740 * actual moving of a single struct pipe_buffer to the desired
741 * destination. It returns when there's no more buffers left in
742 * the pipe or if the requested number of bytes (@sd->total_len)
743 * have been copied. It returns a positive number (one) if the
744 * pipe needs to be filled with more data, zero if the required
745 * number of bytes have been copied and -errno on error.
746 *
747 * This, together with splice_from_pipe_{begin,end,next}, may be
748 * used to implement the functionality of __splice_from_pipe() when
749 * locking is required around copying the pipe buffers to the
750 * destination.
751 */
Al Viro96f9bc82014-04-05 04:35:49 -0400752static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200753 splice_actor *actor)
754{
755 int ret;
756
757 while (pipe->nrbufs) {
758 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
759 const struct pipe_buf_operations *ops = buf->ops;
760
761 sd->len = buf->len;
762 if (sd->len > sd->total_len)
763 sd->len = sd->total_len;
764
Michał Mirosława8adbe32010-12-17 08:56:44 +0100765 ret = buf->ops->confirm(pipe, buf);
766 if (unlikely(ret)) {
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200767 if (ret == -ENODATA)
768 ret = 0;
769 return ret;
770 }
Michał Mirosława8adbe32010-12-17 08:56:44 +0100771
772 ret = actor(pipe, buf, sd);
773 if (ret <= 0)
774 return ret;
775
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200776 buf->offset += ret;
777 buf->len -= ret;
778
779 sd->num_spliced += ret;
780 sd->len -= ret;
781 sd->pos += ret;
782 sd->total_len -= ret;
783
784 if (!buf->len) {
785 buf->ops = NULL;
786 ops->release(pipe, buf);
Jens Axboe35f3d142010-05-20 10:43:18 +0200787 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200788 pipe->nrbufs--;
Al Viro6447a3c2013-03-21 11:01:38 -0400789 if (pipe->files)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200790 sd->need_wakeup = true;
791 }
792
793 if (!sd->total_len)
794 return 0;
795 }
796
797 return 1;
798}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200799
800/**
801 * splice_from_pipe_next - wait for some data to splice from
802 * @pipe: pipe to splice from
803 * @sd: information about the splice operation
804 *
805 * Description:
806 * This function will wait for some data and return a positive
807 * value (one) if pipe buffers are available. It will return zero
808 * or -errno if no more data needs to be spliced.
809 */
Al Viro96f9bc82014-04-05 04:35:49 -0400810static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200811{
Jan Karac725bfc2015-11-23 13:09:50 +0100812 /*
813 * Check for signal early to make process killable when there are
814 * always buffers available
815 */
816 if (signal_pending(current))
817 return -ERESTARTSYS;
818
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200819 while (!pipe->nrbufs) {
820 if (!pipe->writers)
821 return 0;
822
823 if (!pipe->waiting_writers && sd->num_spliced)
824 return 0;
825
826 if (sd->flags & SPLICE_F_NONBLOCK)
827 return -EAGAIN;
828
829 if (signal_pending(current))
830 return -ERESTARTSYS;
831
832 if (sd->need_wakeup) {
833 wakeup_pipe_writers(pipe);
834 sd->need_wakeup = false;
835 }
836
837 pipe_wait(pipe);
838 }
839
840 return 1;
841}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200842
843/**
844 * splice_from_pipe_begin - start splicing from pipe
Randy Dunlapb80901b2009-04-16 19:09:55 -0700845 * @sd: information about the splice operation
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200846 *
847 * Description:
848 * This function should be called before a loop containing
849 * splice_from_pipe_next() and splice_from_pipe_feed() to
850 * initialize the necessary fields of @sd.
851 */
Al Viro96f9bc82014-04-05 04:35:49 -0400852static void splice_from_pipe_begin(struct splice_desc *sd)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200853{
854 sd->num_spliced = 0;
855 sd->need_wakeup = false;
856}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200857
858/**
859 * splice_from_pipe_end - finish splicing from pipe
860 * @pipe: pipe to splice from
861 * @sd: information about the splice operation
862 *
863 * Description:
864 * This function will wake up pipe writers if necessary. It should
865 * be called after a loop containing splice_from_pipe_next() and
866 * splice_from_pipe_feed().
867 */
Al Viro96f9bc82014-04-05 04:35:49 -0400868static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200869{
870 if (sd->need_wakeup)
871 wakeup_pipe_writers(pipe);
872}
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200873
Jens Axboe932cc6d2007-06-21 13:10:21 +0200874/**
875 * __splice_from_pipe - splice data from a pipe to given actor
876 * @pipe: pipe to splice from
877 * @sd: information to @actor
878 * @actor: handler that splices the data
879 *
880 * Description:
881 * This function does little more than loop over the pipe and call
882 * @actor to do the actual moving of a single struct pipe_buffer to
883 * the desired destination. See pipe_to_file, pipe_to_sendpage, or
884 * pipe_to_user.
885 *
Jens Axboe83f91352006-04-02 23:05:09 +0200886 */
Jens Axboec66ab6f2007-06-12 21:17:17 +0200887ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
888 splice_actor *actor)
Jens Axboe5274f052006-03-30 15:15:30 +0200889{
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200890 int ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200891
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200892 splice_from_pipe_begin(sd);
893 do {
Jan Karac2489e02015-11-23 13:09:51 +0100894 cond_resched();
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200895 ret = splice_from_pipe_next(pipe, sd);
896 if (ret > 0)
897 ret = splice_from_pipe_feed(pipe, sd, actor);
898 } while (ret > 0);
899 splice_from_pipe_end(pipe, sd);
Jens Axboe5274f052006-03-30 15:15:30 +0200900
Miklos Szeredib3c2d2d2009-04-14 19:48:36 +0200901 return sd->num_spliced ? sd->num_spliced : ret;
Jens Axboe5274f052006-03-30 15:15:30 +0200902}
Mark Fasheh40bee44e2007-03-21 13:11:02 +0100903EXPORT_SYMBOL(__splice_from_pipe);
Jens Axboe5274f052006-03-30 15:15:30 +0200904
Jens Axboe932cc6d2007-06-21 13:10:21 +0200905/**
906 * splice_from_pipe - splice data from a pipe to a file
907 * @pipe: pipe to splice from
908 * @out: file to splice to
909 * @ppos: position in @out
910 * @len: how many bytes to splice
911 * @flags: splice modifier flags
912 * @actor: handler that splices the data
913 *
914 * Description:
Miklos Szeredi29339702009-04-14 19:48:37 +0200915 * See __splice_from_pipe. This function locks the pipe inode,
Jens Axboe932cc6d2007-06-21 13:10:21 +0200916 * otherwise it's identical to __splice_from_pipe().
917 *
918 */
Mark Fasheh6da61802006-10-17 18:43:07 +0200919ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
920 loff_t *ppos, size_t len, unsigned int flags,
921 splice_actor *actor)
922{
923 ssize_t ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +0200924 struct splice_desc sd = {
925 .total_len = len,
926 .flags = flags,
927 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +0200928 .u.file = out,
Jens Axboec66ab6f2007-06-12 21:17:17 +0200929 };
Mark Fasheh6da61802006-10-17 18:43:07 +0200930
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200931 pipe_lock(pipe);
Jens Axboec66ab6f2007-06-12 21:17:17 +0200932 ret = __splice_from_pipe(pipe, &sd, actor);
Miklos Szeredi61e0d472009-04-14 19:48:41 +0200933 pipe_unlock(pipe);
Mark Fasheh6da61802006-10-17 18:43:07 +0200934
935 return ret;
936}
937
938/**
Al Viro8d020762014-04-05 04:27:08 -0400939 * iter_file_splice_write - splice data from a pipe to a file
940 * @pipe: pipe info
941 * @out: file to write to
942 * @ppos: position in @out
943 * @len: number of bytes to splice
944 * @flags: splice modifier flags
945 *
946 * Description:
947 * Will either move or copy pages (determined by @flags options) from
948 * the given pipe inode to the given file.
949 * This one is ->write_iter-based.
950 *
951 */
952ssize_t
953iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
954 loff_t *ppos, size_t len, unsigned int flags)
955{
956 struct splice_desc sd = {
957 .total_len = len,
958 .flags = flags,
959 .pos = *ppos,
960 .u.file = out,
961 };
962 int nbufs = pipe->buffers;
963 struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
964 GFP_KERNEL);
965 ssize_t ret;
966
967 if (unlikely(!array))
968 return -ENOMEM;
969
970 pipe_lock(pipe);
971
972 splice_from_pipe_begin(&sd);
973 while (sd.total_len) {
974 struct iov_iter from;
Al Viro8d020762014-04-05 04:27:08 -0400975 size_t left;
976 int n, idx;
977
978 ret = splice_from_pipe_next(pipe, &sd);
979 if (ret <= 0)
980 break;
981
982 if (unlikely(nbufs < pipe->buffers)) {
983 kfree(array);
984 nbufs = pipe->buffers;
985 array = kcalloc(nbufs, sizeof(struct bio_vec),
986 GFP_KERNEL);
987 if (!array) {
988 ret = -ENOMEM;
989 break;
990 }
991 }
992
993 /* build the vector */
994 left = sd.total_len;
995 for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) {
996 struct pipe_buffer *buf = pipe->bufs + idx;
997 size_t this_len = buf->len;
998
999 if (this_len > left)
1000 this_len = left;
1001
1002 if (idx == pipe->buffers - 1)
1003 idx = -1;
1004
1005 ret = buf->ops->confirm(pipe, buf);
1006 if (unlikely(ret)) {
1007 if (ret == -ENODATA)
1008 ret = 0;
1009 goto done;
1010 }
1011
1012 array[n].bv_page = buf->page;
1013 array[n].bv_len = this_len;
1014 array[n].bv_offset = buf->offset;
1015 left -= this_len;
1016 }
1017
Al Viro05afcb72015-01-23 01:08:07 -05001018 iov_iter_bvec(&from, ITER_BVEC | WRITE, array, n,
1019 sd.total_len - left);
Christoph Hellwigdbe4e192015-01-25 21:11:59 +01001020 ret = vfs_iter_write(out, &from, &sd.pos);
Al Viro8d020762014-04-05 04:27:08 -04001021 if (ret <= 0)
1022 break;
1023
1024 sd.num_spliced += ret;
1025 sd.total_len -= ret;
Christoph Hellwigdbe4e192015-01-25 21:11:59 +01001026 *ppos = sd.pos;
Al Viro8d020762014-04-05 04:27:08 -04001027
1028 /* dismiss the fully eaten buffers, adjust the partial one */
1029 while (ret) {
1030 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
1031 if (ret >= buf->len) {
1032 const struct pipe_buf_operations *ops = buf->ops;
1033 ret -= buf->len;
1034 buf->len = 0;
1035 buf->ops = NULL;
1036 ops->release(pipe, buf);
1037 pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
1038 pipe->nrbufs--;
1039 if (pipe->files)
1040 sd.need_wakeup = true;
1041 } else {
1042 buf->offset += ret;
1043 buf->len -= ret;
1044 ret = 0;
1045 }
1046 }
1047 }
1048done:
1049 kfree(array);
1050 splice_from_pipe_end(pipe, &sd);
1051
1052 pipe_unlock(pipe);
1053
1054 if (sd.num_spliced)
1055 ret = sd.num_spliced;
1056
1057 return ret;
1058}
1059
1060EXPORT_SYMBOL(iter_file_splice_write);
1061
Miklos Szeredib2858d72009-05-19 11:37:46 +02001062static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1063 struct splice_desc *sd)
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001064{
Miklos Szeredib2858d72009-05-19 11:37:46 +02001065 int ret;
1066 void *data;
Al Viro06ae43f2013-03-20 13:19:30 -04001067 loff_t tmp = sd->pos;
Miklos Szeredib2858d72009-05-19 11:37:46 +02001068
Al Virofbb32752014-02-02 21:09:54 -05001069 data = kmap(buf->page);
Al Viro06ae43f2013-03-20 13:19:30 -04001070 ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
Al Virofbb32752014-02-02 21:09:54 -05001071 kunmap(buf->page);
Miklos Szeredib2858d72009-05-19 11:37:46 +02001072
1073 return ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001074}
1075
1076static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
1077 struct file *out, loff_t *ppos,
1078 size_t len, unsigned int flags)
1079{
Miklos Szeredib2858d72009-05-19 11:37:46 +02001080 ssize_t ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001081
Miklos Szeredib2858d72009-05-19 11:37:46 +02001082 ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
1083 if (ret > 0)
1084 *ppos += ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001085
Miklos Szeredib2858d72009-05-19 11:37:46 +02001086 return ret;
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001087}
1088
Jens Axboe83f91352006-04-02 23:05:09 +02001089/**
1090 * generic_splice_sendpage - splice data from a pipe to a socket
Jens Axboe932cc6d2007-06-21 13:10:21 +02001091 * @pipe: pipe to splice from
Jens Axboe83f91352006-04-02 23:05:09 +02001092 * @out: socket to write to
Jens Axboe932cc6d2007-06-21 13:10:21 +02001093 * @ppos: position in @out
Jens Axboe83f91352006-04-02 23:05:09 +02001094 * @len: number of bytes to splice
1095 * @flags: splice modifier flags
1096 *
Jens Axboe932cc6d2007-06-21 13:10:21 +02001097 * Description:
1098 * Will send @len bytes from the pipe to a network socket. No data copying
1099 * is involved.
Jens Axboe83f91352006-04-02 23:05:09 +02001100 *
1101 */
Ingo Molnar3a326a22006-04-10 15:18:35 +02001102ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +02001103 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001104{
Jens Axboe00522fb2006-04-26 14:39:29 +02001105 return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
Jens Axboe5274f052006-03-30 15:15:30 +02001106}
1107
Jens Axboe059a8f32006-04-02 23:06:05 +02001108EXPORT_SYMBOL(generic_splice_sendpage);
Jeff Garzika0f06782006-03-30 23:06:13 -05001109
Jens Axboe83f91352006-04-02 23:05:09 +02001110/*
1111 * Attempt to initiate a splice from pipe to file.
1112 */
Ingo Molnar3a326a22006-04-10 15:18:35 +02001113static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
Jens Axboecbb7e572006-04-11 14:57:50 +02001114 loff_t *ppos, size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001115{
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001116 ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
1117 loff_t *, size_t, unsigned int);
Jens Axboe5274f052006-03-30 15:15:30 +02001118
Al Viro72c2d532013-09-22 16:27:52 -04001119 if (out->f_op->splice_write)
Changli Gaocc56f7d2009-11-04 09:09:52 +01001120 splice_write = out->f_op->splice_write;
1121 else
Miklos Szeredi0b0a47f2009-05-07 15:37:37 +02001122 splice_write = default_file_splice_write;
1123
Al Viro500368f2013-05-23 20:07:11 -04001124 return splice_write(pipe, out, ppos, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001125}
1126
Jens Axboe83f91352006-04-02 23:05:09 +02001127/*
1128 * Attempt to initiate a splice from a file to a pipe.
1129 */
Jens Axboecbb7e572006-04-11 14:57:50 +02001130static long do_splice_to(struct file *in, loff_t *ppos,
1131 struct pipe_inode_info *pipe, size_t len,
1132 unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001133{
Miklos Szeredi68181732009-05-07 15:37:36 +02001134 ssize_t (*splice_read)(struct file *, loff_t *,
1135 struct pipe_inode_info *, size_t, unsigned int);
Jens Axboe5274f052006-03-30 15:15:30 +02001136 int ret;
1137
Jens Axboe49570e92006-04-11 13:56:09 +02001138 if (unlikely(!(in->f_mode & FMODE_READ)))
Jens Axboe5274f052006-03-30 15:15:30 +02001139 return -EBADF;
1140
Jens Axboecbb7e572006-04-11 14:57:50 +02001141 ret = rw_verify_area(READ, in, ppos, len);
Jens Axboe5274f052006-03-30 15:15:30 +02001142 if (unlikely(ret < 0))
1143 return ret;
1144
Al Viro72c2d532013-09-22 16:27:52 -04001145 if (in->f_op->splice_read)
Changli Gaocc56f7d2009-11-04 09:09:52 +01001146 splice_read = in->f_op->splice_read;
1147 else
Miklos Szeredi68181732009-05-07 15:37:36 +02001148 splice_read = default_file_splice_read;
1149
1150 return splice_read(in, ppos, pipe, len, flags);
Jens Axboe5274f052006-03-30 15:15:30 +02001151}
1152
Jens Axboe932cc6d2007-06-21 13:10:21 +02001153/**
1154 * splice_direct_to_actor - splices data directly between two non-pipes
1155 * @in: file to splice from
1156 * @sd: actor information on where to splice to
1157 * @actor: handles the data splicing
1158 *
1159 * Description:
1160 * This is a special case helper to splice directly between two
1161 * points, without requiring an explicit pipe. Internally an allocated
Randy Dunlap79685b82007-07-27 08:08:51 +02001162 * pipe is cached in the process, and reused during the lifetime of
Jens Axboe932cc6d2007-06-21 13:10:21 +02001163 * that process.
1164 *
Jens Axboec66ab6f2007-06-12 21:17:17 +02001165 */
1166ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
1167 splice_direct_actor *actor)
Jens Axboeb92ce552006-04-11 13:52:07 +02001168{
1169 struct pipe_inode_info *pipe;
1170 long ret, bytes;
1171 umode_t i_mode;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001172 size_t len;
Christophe Leroy0ff28d92015-05-06 17:26:47 +02001173 int i, flags, more;
Jens Axboeb92ce552006-04-11 13:52:07 +02001174
1175 /*
1176 * We require the input being a regular file, as we don't want to
1177 * randomly drop data for eg socket -> socket splicing. Use the
1178 * piped splicing for that!
1179 */
Al Viro496ad9a2013-01-23 17:07:38 -05001180 i_mode = file_inode(in)->i_mode;
Jens Axboeb92ce552006-04-11 13:52:07 +02001181 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
1182 return -EINVAL;
1183
1184 /*
1185 * neither in nor out is a pipe, setup an internal pipe attached to
1186 * 'out' and transfer the wanted data from 'in' to 'out' through that
1187 */
1188 pipe = current->splice_pipe;
Jens Axboe49570e92006-04-11 13:56:09 +02001189 if (unlikely(!pipe)) {
Al Viro7bee1302013-03-21 11:04:15 -04001190 pipe = alloc_pipe_info();
Jens Axboeb92ce552006-04-11 13:52:07 +02001191 if (!pipe)
1192 return -ENOMEM;
1193
1194 /*
1195 * We don't have an immediate reader, but we'll read the stuff
Jens Axboe00522fb2006-04-26 14:39:29 +02001196 * out of the pipe right after the splice_to_pipe(). So set
Jens Axboeb92ce552006-04-11 13:52:07 +02001197 * PIPE_READERS appropriately.
1198 */
1199 pipe->readers = 1;
1200
1201 current->splice_pipe = pipe;
1202 }
1203
1204 /*
Ingo Molnar73d62d82006-04-11 13:57:21 +02001205 * Do the splice.
Jens Axboeb92ce552006-04-11 13:52:07 +02001206 */
1207 ret = 0;
1208 bytes = 0;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001209 len = sd->total_len;
1210 flags = sd->flags;
1211
1212 /*
1213 * Don't block on output, we have to drain the direct pipe.
1214 */
1215 sd->flags &= ~SPLICE_F_NONBLOCK;
Christophe Leroy0ff28d92015-05-06 17:26:47 +02001216 more = sd->flags & SPLICE_F_MORE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001217
1218 while (len) {
Jens Axboe51a92c02007-07-13 14:11:43 +02001219 size_t read_len;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001220 loff_t pos = sd->pos, prev_pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001221
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001222 ret = do_splice_to(in, &pos, pipe, len, flags);
Jens Axboe51a92c02007-07-13 14:11:43 +02001223 if (unlikely(ret <= 0))
Jens Axboeb92ce552006-04-11 13:52:07 +02001224 goto out_release;
1225
1226 read_len = ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001227 sd->total_len = read_len;
Jens Axboeb92ce552006-04-11 13:52:07 +02001228
1229 /*
Christophe Leroy0ff28d92015-05-06 17:26:47 +02001230 * If more data is pending, set SPLICE_F_MORE
1231 * If this is the last data and SPLICE_F_MORE was not set
1232 * initially, clears it.
1233 */
1234 if (read_len < len)
1235 sd->flags |= SPLICE_F_MORE;
1236 else if (!more)
1237 sd->flags &= ~SPLICE_F_MORE;
1238 /*
Jens Axboeb92ce552006-04-11 13:52:07 +02001239 * NOTE: nonblocking mode only applies to the input. We
1240 * must not do the output in nonblocking mode as then we
1241 * could get stuck data in the internal pipe:
1242 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001243 ret = actor(pipe, sd);
Tom Zanussia82c53a2008-05-09 13:28:36 +02001244 if (unlikely(ret <= 0)) {
1245 sd->pos = prev_pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001246 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001247 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001248
1249 bytes += ret;
1250 len -= ret;
Jens Axboebcd4f3a2007-07-16 14:41:49 +02001251 sd->pos = pos;
Jens Axboeb92ce552006-04-11 13:52:07 +02001252
Tom Zanussia82c53a2008-05-09 13:28:36 +02001253 if (ret < read_len) {
1254 sd->pos = prev_pos + ret;
Jens Axboe51a92c02007-07-13 14:11:43 +02001255 goto out_release;
Tom Zanussia82c53a2008-05-09 13:28:36 +02001256 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001257 }
1258
Jens Axboe9e971982008-01-29 21:05:57 +01001259done:
Jens Axboeb92ce552006-04-11 13:52:07 +02001260 pipe->nrbufs = pipe->curbuf = 0;
Jens Axboe80848702008-01-30 12:24:48 +01001261 file_accessed(in);
Jens Axboeb92ce552006-04-11 13:52:07 +02001262 return bytes;
1263
1264out_release:
1265 /*
1266 * If we did an incomplete transfer we must release
1267 * the pipe buffers in question:
1268 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001269 for (i = 0; i < pipe->buffers; i++) {
Jens Axboeb92ce552006-04-11 13:52:07 +02001270 struct pipe_buffer *buf = pipe->bufs + i;
1271
1272 if (buf->ops) {
1273 buf->ops->release(pipe, buf);
1274 buf->ops = NULL;
1275 }
1276 }
Jens Axboeb92ce552006-04-11 13:52:07 +02001277
Jens Axboe9e971982008-01-29 21:05:57 +01001278 if (!bytes)
1279 bytes = ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001280
Jens Axboe9e971982008-01-29 21:05:57 +01001281 goto done;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001282}
1283EXPORT_SYMBOL(splice_direct_to_actor);
1284
1285static int direct_splice_actor(struct pipe_inode_info *pipe,
1286 struct splice_desc *sd)
1287{
Jens Axboe6a14b902007-06-14 13:08:55 +02001288 struct file *file = sd->u.file;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001289
Al Viro7995bd22013-06-20 18:58:36 +04001290 return do_splice_from(pipe, file, sd->opos, sd->total_len,
Changli Gao2cb4b052010-06-29 13:09:18 +02001291 sd->flags);
Jens Axboec66ab6f2007-06-12 21:17:17 +02001292}
1293
Jens Axboe932cc6d2007-06-21 13:10:21 +02001294/**
1295 * do_splice_direct - splices data directly between two files
1296 * @in: file to splice from
1297 * @ppos: input file offset
1298 * @out: file to splice to
Randy Dunlapacdb37c2013-06-22 19:44:08 -07001299 * @opos: output file offset
Jens Axboe932cc6d2007-06-21 13:10:21 +02001300 * @len: number of bytes to splice
1301 * @flags: splice modifier flags
1302 *
1303 * Description:
1304 * For use by do_sendfile(). splice can easily emulate sendfile, but
1305 * doing it in the application would incur an extra system call
1306 * (splice in + splice out, as compared to just sendfile()). So this helper
1307 * can splice directly through a process-private pipe.
1308 *
1309 */
Jens Axboec66ab6f2007-06-12 21:17:17 +02001310long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
Al Viro7995bd22013-06-20 18:58:36 +04001311 loff_t *opos, size_t len, unsigned int flags)
Jens Axboec66ab6f2007-06-12 21:17:17 +02001312{
1313 struct splice_desc sd = {
1314 .len = len,
1315 .total_len = len,
1316 .flags = flags,
1317 .pos = *ppos,
Jens Axboe6a14b902007-06-14 13:08:55 +02001318 .u.file = out,
Al Viro7995bd22013-06-20 18:58:36 +04001319 .opos = opos,
Jens Axboec66ab6f2007-06-12 21:17:17 +02001320 };
Jens Axboe51a92c02007-07-13 14:11:43 +02001321 long ret;
Jens Axboec66ab6f2007-06-12 21:17:17 +02001322
Al Viro18c67cb2013-06-19 15:41:54 +04001323 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1324 return -EBADF;
1325
1326 if (unlikely(out->f_flags & O_APPEND))
1327 return -EINVAL;
1328
1329 ret = rw_verify_area(WRITE, out, opos, len);
1330 if (unlikely(ret < 0))
1331 return ret;
1332
Jens Axboec66ab6f2007-06-12 21:17:17 +02001333 ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
Jens Axboe51a92c02007-07-13 14:11:43 +02001334 if (ret > 0)
Tom Zanussia82c53a2008-05-09 13:28:36 +02001335 *ppos = sd.pos;
Jens Axboe51a92c02007-07-13 14:11:43 +02001336
Jens Axboec66ab6f2007-06-12 21:17:17 +02001337 return ret;
Jens Axboeb92ce552006-04-11 13:52:07 +02001338}
Miklos Szeredi1c118592014-10-24 00:14:35 +02001339EXPORT_SYMBOL(do_splice_direct);
Jens Axboeb92ce552006-04-11 13:52:07 +02001340
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001341static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1342 struct pipe_inode_info *opipe,
1343 size_t len, unsigned int flags);
Jens Axboeddac0d32006-11-04 12:49:32 +01001344
1345/*
Jens Axboe83f91352006-04-02 23:05:09 +02001346 * Determine where to splice to/from.
1347 */
Ingo Molnar529565d2006-04-10 15:18:58 +02001348static long do_splice(struct file *in, loff_t __user *off_in,
1349 struct file *out, loff_t __user *off_out,
1350 size_t len, unsigned int flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001351{
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001352 struct pipe_inode_info *ipipe;
1353 struct pipe_inode_info *opipe;
Al Viro7995bd22013-06-20 18:58:36 +04001354 loff_t offset;
Jens Axboea4514eb2006-04-19 15:57:05 +02001355 long ret;
Jens Axboe5274f052006-03-30 15:15:30 +02001356
Linus Torvalds71993e62010-11-28 13:56:09 -08001357 ipipe = get_pipe_info(in);
1358 opipe = get_pipe_info(out);
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001359
1360 if (ipipe && opipe) {
1361 if (off_in || off_out)
1362 return -ESPIPE;
1363
1364 if (!(in->f_mode & FMODE_READ))
1365 return -EBADF;
1366
1367 if (!(out->f_mode & FMODE_WRITE))
1368 return -EBADF;
1369
1370 /* Splicing to self would be fun, but... */
1371 if (ipipe == opipe)
1372 return -EINVAL;
1373
1374 return splice_pipe_to_pipe(ipipe, opipe, len, flags);
1375 }
1376
1377 if (ipipe) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001378 if (off_in)
1379 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001380 if (off_out) {
Changli Gao19c9a492010-06-29 13:10:36 +02001381 if (!(out->f_mode & FMODE_PWRITE))
Jens Axboeb92ce552006-04-11 13:52:07 +02001382 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001383 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001384 return -EFAULT;
Al Viro7995bd22013-06-20 18:58:36 +04001385 } else {
1386 offset = out->f_pos;
1387 }
Ingo Molnar529565d2006-04-10 15:18:58 +02001388
Al Viro18c67cb2013-06-19 15:41:54 +04001389 if (unlikely(!(out->f_mode & FMODE_WRITE)))
1390 return -EBADF;
1391
1392 if (unlikely(out->f_flags & O_APPEND))
1393 return -EINVAL;
1394
1395 ret = rw_verify_area(WRITE, out, &offset, len);
1396 if (unlikely(ret < 0))
1397 return ret;
1398
Al Viro500368f2013-05-23 20:07:11 -04001399 file_start_write(out);
Al Viro7995bd22013-06-20 18:58:36 +04001400 ret = do_splice_from(ipipe, out, &offset, len, flags);
Al Viro500368f2013-05-23 20:07:11 -04001401 file_end_write(out);
Jens Axboea4514eb2006-04-19 15:57:05 +02001402
Al Viro7995bd22013-06-20 18:58:36 +04001403 if (!off_out)
1404 out->f_pos = offset;
1405 else if (copy_to_user(off_out, &offset, sizeof(loff_t)))
Jens Axboea4514eb2006-04-19 15:57:05 +02001406 ret = -EFAULT;
1407
1408 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001409 }
Jens Axboe5274f052006-03-30 15:15:30 +02001410
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001411 if (opipe) {
Ingo Molnar529565d2006-04-10 15:18:58 +02001412 if (off_out)
1413 return -ESPIPE;
Jens Axboeb92ce552006-04-11 13:52:07 +02001414 if (off_in) {
Changli Gao19c9a492010-06-29 13:10:36 +02001415 if (!(in->f_mode & FMODE_PREAD))
Jens Axboeb92ce552006-04-11 13:52:07 +02001416 return -EINVAL;
Jens Axboecbb7e572006-04-11 14:57:50 +02001417 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
Jens Axboeb92ce552006-04-11 13:52:07 +02001418 return -EFAULT;
Al Viro7995bd22013-06-20 18:58:36 +04001419 } else {
1420 offset = in->f_pos;
1421 }
Ingo Molnar529565d2006-04-10 15:18:58 +02001422
Al Viro7995bd22013-06-20 18:58:36 +04001423 ret = do_splice_to(in, &offset, opipe, len, flags);
Jens Axboea4514eb2006-04-19 15:57:05 +02001424
Al Viro7995bd22013-06-20 18:58:36 +04001425 if (!off_in)
1426 in->f_pos = offset;
1427 else if (copy_to_user(off_in, &offset, sizeof(loff_t)))
Jens Axboea4514eb2006-04-19 15:57:05 +02001428 ret = -EFAULT;
1429
1430 return ret;
Ingo Molnar529565d2006-04-10 15:18:58 +02001431 }
Jens Axboe5274f052006-03-30 15:15:30 +02001432
1433 return -EINVAL;
1434}
1435
Jens Axboe912d35f2006-04-26 10:59:21 +02001436/*
1437 * Map an iov into an array of pages and offset/length tupples. With the
1438 * partial_page structure, we can map several non-contiguous ranges into
1439 * our ones pages[] map instead of splitting that operation into pieces.
1440 * Could easily be exported as a generic helper for other users, in which
1441 * case one would probably want to add a 'max_nr_pages' parameter as well.
1442 */
1443static int get_iovec_page_array(const struct iovec __user *iov,
1444 unsigned int nr_vecs, struct page **pages,
Eric Dumazetbd1a68b2012-04-04 11:08:51 +02001445 struct partial_page *partial, bool aligned,
Jens Axboe35f3d142010-05-20 10:43:18 +02001446 unsigned int pipe_buffers)
Jens Axboe912d35f2006-04-26 10:59:21 +02001447{
1448 int buffers = 0, error = 0;
1449
Jens Axboe912d35f2006-04-26 10:59:21 +02001450 while (nr_vecs) {
1451 unsigned long off, npages;
Linus Torvalds75723952007-10-01 13:17:28 -07001452 struct iovec entry;
Jens Axboe912d35f2006-04-26 10:59:21 +02001453 void __user *base;
1454 size_t len;
1455 int i;
1456
Linus Torvalds75723952007-10-01 13:17:28 -07001457 error = -EFAULT;
Nick Pigginbc40d732008-07-25 19:45:26 -07001458 if (copy_from_user(&entry, iov, sizeof(entry)))
Jens Axboe912d35f2006-04-26 10:59:21 +02001459 break;
Linus Torvalds75723952007-10-01 13:17:28 -07001460
1461 base = entry.iov_base;
1462 len = entry.iov_len;
Jens Axboe912d35f2006-04-26 10:59:21 +02001463
1464 /*
1465 * Sanity check this iovec. 0 read succeeds.
1466 */
Linus Torvalds75723952007-10-01 13:17:28 -07001467 error = 0;
Jens Axboe912d35f2006-04-26 10:59:21 +02001468 if (unlikely(!len))
1469 break;
1470 error = -EFAULT;
Bastian Blank712a30e2008-02-10 16:47:57 +02001471 if (!access_ok(VERIFY_READ, base, len))
Jens Axboe912d35f2006-04-26 10:59:21 +02001472 break;
1473
1474 /*
1475 * Get this base offset and number of pages, then map
1476 * in the user pages.
1477 */
1478 off = (unsigned long) base & ~PAGE_MASK;
Jens Axboe7afa6fd2006-05-01 20:02:33 +02001479
1480 /*
1481 * If asked for alignment, the offset must be zero and the
1482 * length a multiple of the PAGE_SIZE.
1483 */
1484 error = -EINVAL;
1485 if (aligned && (off || len & ~PAGE_MASK))
1486 break;
1487
Jens Axboe912d35f2006-04-26 10:59:21 +02001488 npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
Jens Axboe35f3d142010-05-20 10:43:18 +02001489 if (npages > pipe_buffers - buffers)
1490 npages = pipe_buffers - buffers;
Jens Axboe912d35f2006-04-26 10:59:21 +02001491
Nick Pigginbc40d732008-07-25 19:45:26 -07001492 error = get_user_pages_fast((unsigned long)base, npages,
1493 0, &pages[buffers]);
Jens Axboe912d35f2006-04-26 10:59:21 +02001494
1495 if (unlikely(error <= 0))
1496 break;
1497
1498 /*
1499 * Fill this contiguous range into the partial page map.
1500 */
1501 for (i = 0; i < error; i++) {
Jens Axboe75914892006-05-02 12:57:18 +02001502 const int plen = min_t(size_t, len, PAGE_SIZE - off);
Jens Axboe912d35f2006-04-26 10:59:21 +02001503
1504 partial[buffers].offset = off;
1505 partial[buffers].len = plen;
1506
1507 off = 0;
1508 len -= plen;
1509 buffers++;
1510 }
1511
1512 /*
1513 * We didn't complete this iov, stop here since it probably
1514 * means we have to move some of this into a pipe to
1515 * be able to continue.
1516 */
1517 if (len)
1518 break;
1519
1520 /*
1521 * Don't continue if we mapped fewer pages than we asked for,
1522 * or if we mapped the max number of pages that we have
1523 * room for.
1524 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001525 if (error < npages || buffers == pipe_buffers)
Jens Axboe912d35f2006-04-26 10:59:21 +02001526 break;
1527
1528 nr_vecs--;
1529 iov++;
1530 }
1531
Jens Axboe912d35f2006-04-26 10:59:21 +02001532 if (buffers)
1533 return buffers;
1534
1535 return error;
1536}
1537
Jens Axboe6a14b902007-06-14 13:08:55 +02001538static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
1539 struct splice_desc *sd)
1540{
Al Viro6130f532014-02-03 18:19:51 -05001541 int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
1542 return n == sd->len ? n : -EFAULT;
Jens Axboe6a14b902007-06-14 13:08:55 +02001543}
1544
1545/*
1546 * For lack of a better implementation, implement vmsplice() to userspace
1547 * as a simple copy of the pipes pages to the user iov.
1548 */
Al Viro6130f532014-02-03 18:19:51 -05001549static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
Jens Axboe6a14b902007-06-14 13:08:55 +02001550 unsigned long nr_segs, unsigned int flags)
1551{
1552 struct pipe_inode_info *pipe;
1553 struct splice_desc sd;
Jens Axboe6a14b902007-06-14 13:08:55 +02001554 long ret;
Al Viro6130f532014-02-03 18:19:51 -05001555 struct iovec iovstack[UIO_FASTIOV];
1556 struct iovec *iov = iovstack;
1557 struct iov_iter iter;
Jens Axboe6a14b902007-06-14 13:08:55 +02001558
Linus Torvalds71993e62010-11-28 13:56:09 -08001559 pipe = get_pipe_info(file);
Jens Axboe6a14b902007-06-14 13:08:55 +02001560 if (!pipe)
1561 return -EBADF;
1562
Al Viro345995f2015-03-21 19:17:55 -04001563 ret = import_iovec(READ, uiov, nr_segs,
1564 ARRAY_SIZE(iovstack), &iov, &iter);
1565 if (ret < 0)
1566 return ret;
Al Viro6130f532014-02-03 18:19:51 -05001567
Al Viro345995f2015-03-21 19:17:55 -04001568 sd.total_len = iov_iter_count(&iter);
Al Viro6130f532014-02-03 18:19:51 -05001569 sd.len = 0;
Al Viro6130f532014-02-03 18:19:51 -05001570 sd.flags = flags;
1571 sd.u.data = &iter;
1572 sd.pos = 0;
1573
Al Viro345995f2015-03-21 19:17:55 -04001574 if (sd.total_len) {
1575 pipe_lock(pipe);
1576 ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
1577 pipe_unlock(pipe);
1578 }
Jens Axboe6a14b902007-06-14 13:08:55 +02001579
Al Viro345995f2015-03-21 19:17:55 -04001580 kfree(iov);
Jens Axboe6a14b902007-06-14 13:08:55 +02001581 return ret;
1582}
1583
Jens Axboe912d35f2006-04-26 10:59:21 +02001584/*
1585 * vmsplice splices a user address range into a pipe. It can be thought of
1586 * as splice-from-memory, where the regular splice is splice-from-file (or
1587 * to file). In both cases the output is a pipe, naturally.
Jens Axboe912d35f2006-04-26 10:59:21 +02001588 */
Jens Axboe6a14b902007-06-14 13:08:55 +02001589static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
1590 unsigned long nr_segs, unsigned int flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001591{
Jens Axboeddac0d32006-11-04 12:49:32 +01001592 struct pipe_inode_info *pipe;
Jens Axboe35f3d142010-05-20 10:43:18 +02001593 struct page *pages[PIPE_DEF_BUFFERS];
1594 struct partial_page partial[PIPE_DEF_BUFFERS];
Jens Axboe912d35f2006-04-26 10:59:21 +02001595 struct splice_pipe_desc spd = {
1596 .pages = pages,
1597 .partial = partial,
Eric Dumazet047fe362012-06-12 15:24:40 +02001598 .nr_pages_max = PIPE_DEF_BUFFERS,
Jens Axboe912d35f2006-04-26 10:59:21 +02001599 .flags = flags,
1600 .ops = &user_page_pipe_buf_ops,
Jens Axboebbdfc2f2007-11-06 23:29:47 -08001601 .spd_release = spd_release_page,
Jens Axboe912d35f2006-04-26 10:59:21 +02001602 };
Jens Axboe35f3d142010-05-20 10:43:18 +02001603 long ret;
Jens Axboe912d35f2006-04-26 10:59:21 +02001604
Linus Torvalds71993e62010-11-28 13:56:09 -08001605 pipe = get_pipe_info(file);
Jens Axboeddac0d32006-11-04 12:49:32 +01001606 if (!pipe)
Jens Axboe912d35f2006-04-26 10:59:21 +02001607 return -EBADF;
Jens Axboe912d35f2006-04-26 10:59:21 +02001608
Jens Axboe35f3d142010-05-20 10:43:18 +02001609 if (splice_grow_spd(pipe, &spd))
1610 return -ENOMEM;
Jens Axboe912d35f2006-04-26 10:59:21 +02001611
Jens Axboe35f3d142010-05-20 10:43:18 +02001612 spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
Eric Dumazetbd1a68b2012-04-04 11:08:51 +02001613 spd.partial, false,
Eric Dumazet047fe362012-06-12 15:24:40 +02001614 spd.nr_pages_max);
Jens Axboe35f3d142010-05-20 10:43:18 +02001615 if (spd.nr_pages <= 0)
1616 ret = spd.nr_pages;
1617 else
1618 ret = splice_to_pipe(pipe, &spd);
1619
Eric Dumazet047fe362012-06-12 15:24:40 +02001620 splice_shrink_spd(&spd);
Jens Axboe35f3d142010-05-20 10:43:18 +02001621 return ret;
Jens Axboe912d35f2006-04-26 10:59:21 +02001622}
1623
Jens Axboe6a14b902007-06-14 13:08:55 +02001624/*
1625 * Note that vmsplice only really supports true splicing _from_ user memory
1626 * to a pipe, not the other way around. Splicing from user memory is a simple
1627 * operation that can be supported without any funky alignment restrictions
1628 * or nasty vm tricks. We simply map in the user memory and fill them into
1629 * a pipe. The reverse isn't quite as easy, though. There are two possible
1630 * solutions for that:
1631 *
1632 * - memcpy() the data internally, at which point we might as well just
1633 * do a regular read() on the buffer anyway.
1634 * - Lots of nasty vm tricks, that are neither fast nor flexible (it
1635 * has restriction limitations on both ends of the pipe).
1636 *
1637 * Currently we punt and implement it as a normal copy, see pipe_to_user().
1638 *
1639 */
Heiko Carstens836f92a2009-01-14 14:14:33 +01001640SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
1641 unsigned long, nr_segs, unsigned int, flags)
Jens Axboe912d35f2006-04-26 10:59:21 +02001642{
Al Viro2903ff02012-08-28 12:52:22 -04001643 struct fd f;
Jens Axboe912d35f2006-04-26 10:59:21 +02001644 long error;
Jens Axboe912d35f2006-04-26 10:59:21 +02001645
Jens Axboe6a14b902007-06-14 13:08:55 +02001646 if (unlikely(nr_segs > UIO_MAXIOV))
1647 return -EINVAL;
1648 else if (unlikely(!nr_segs))
1649 return 0;
1650
Jens Axboe912d35f2006-04-26 10:59:21 +02001651 error = -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -04001652 f = fdget(fd);
1653 if (f.file) {
1654 if (f.file->f_mode & FMODE_WRITE)
1655 error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
1656 else if (f.file->f_mode & FMODE_READ)
1657 error = vmsplice_to_user(f.file, iov, nr_segs, flags);
Jens Axboe912d35f2006-04-26 10:59:21 +02001658
Al Viro2903ff02012-08-28 12:52:22 -04001659 fdput(f);
Jens Axboe912d35f2006-04-26 10:59:21 +02001660 }
1661
1662 return error;
1663}
1664
Al Viro76b021d2013-03-02 10:19:56 -05001665#ifdef CONFIG_COMPAT
1666COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
1667 unsigned int, nr_segs, unsigned int, flags)
1668{
1669 unsigned i;
1670 struct iovec __user *iov;
1671 if (nr_segs > UIO_MAXIOV)
1672 return -EINVAL;
1673 iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
1674 for (i = 0; i < nr_segs; i++) {
1675 struct compat_iovec v;
1676 if (get_user(v.iov_base, &iov32[i].iov_base) ||
1677 get_user(v.iov_len, &iov32[i].iov_len) ||
1678 put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
1679 put_user(v.iov_len, &iov[i].iov_len))
1680 return -EFAULT;
1681 }
1682 return sys_vmsplice(fd, iov, nr_segs, flags);
1683}
1684#endif
1685
Heiko Carstens836f92a2009-01-14 14:14:33 +01001686SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
1687 int, fd_out, loff_t __user *, off_out,
1688 size_t, len, unsigned int, flags)
Jens Axboe5274f052006-03-30 15:15:30 +02001689{
Al Viro2903ff02012-08-28 12:52:22 -04001690 struct fd in, out;
Jens Axboe5274f052006-03-30 15:15:30 +02001691 long error;
Jens Axboe5274f052006-03-30 15:15:30 +02001692
1693 if (unlikely(!len))
1694 return 0;
1695
1696 error = -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -04001697 in = fdget(fd_in);
1698 if (in.file) {
1699 if (in.file->f_mode & FMODE_READ) {
1700 out = fdget(fd_out);
1701 if (out.file) {
1702 if (out.file->f_mode & FMODE_WRITE)
1703 error = do_splice(in.file, off_in,
1704 out.file, off_out,
Ingo Molnar529565d2006-04-10 15:18:58 +02001705 len, flags);
Al Viro2903ff02012-08-28 12:52:22 -04001706 fdput(out);
Jens Axboe5274f052006-03-30 15:15:30 +02001707 }
1708 }
Al Viro2903ff02012-08-28 12:52:22 -04001709 fdput(in);
Jens Axboe5274f052006-03-30 15:15:30 +02001710 }
Jens Axboe5274f052006-03-30 15:15:30 +02001711 return error;
1712}
Jens Axboe70524492006-04-11 15:51:17 +02001713
1714/*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001715 * Make sure there's data to read. Wait for input if we can, otherwise
1716 * return an appropriate error.
1717 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001718static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001719{
1720 int ret;
1721
1722 /*
1723 * Check ->nrbufs without the inode lock first. This function
1724 * is speculative anyways, so missing one is ok.
1725 */
1726 if (pipe->nrbufs)
1727 return 0;
1728
1729 ret = 0;
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001730 pipe_lock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001731
1732 while (!pipe->nrbufs) {
1733 if (signal_pending(current)) {
1734 ret = -ERESTARTSYS;
1735 break;
1736 }
1737 if (!pipe->writers)
1738 break;
1739 if (!pipe->waiting_writers) {
1740 if (flags & SPLICE_F_NONBLOCK) {
1741 ret = -EAGAIN;
1742 break;
1743 }
1744 }
1745 pipe_wait(pipe);
1746 }
1747
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001748 pipe_unlock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001749 return ret;
1750}
1751
1752/*
1753 * Make sure there's writeable room. Wait for room if we can, otherwise
1754 * return an appropriate error.
1755 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001756static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001757{
1758 int ret;
1759
1760 /*
1761 * Check ->nrbufs without the inode lock first. This function
1762 * is speculative anyways, so missing one is ok.
1763 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001764 if (pipe->nrbufs < pipe->buffers)
Jens Axboeaadd06e2006-07-10 11:00:01 +02001765 return 0;
1766
1767 ret = 0;
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001768 pipe_lock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001769
Jens Axboe35f3d142010-05-20 10:43:18 +02001770 while (pipe->nrbufs >= pipe->buffers) {
Jens Axboeaadd06e2006-07-10 11:00:01 +02001771 if (!pipe->readers) {
1772 send_sig(SIGPIPE, current, 0);
1773 ret = -EPIPE;
1774 break;
1775 }
1776 if (flags & SPLICE_F_NONBLOCK) {
1777 ret = -EAGAIN;
1778 break;
1779 }
1780 if (signal_pending(current)) {
1781 ret = -ERESTARTSYS;
1782 break;
1783 }
1784 pipe->waiting_writers++;
1785 pipe_wait(pipe);
1786 pipe->waiting_writers--;
1787 }
1788
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001789 pipe_unlock(pipe);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001790 return ret;
1791}
1792
1793/*
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001794 * Splice contents of ipipe to opipe.
1795 */
1796static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
1797 struct pipe_inode_info *opipe,
1798 size_t len, unsigned int flags)
1799{
1800 struct pipe_buffer *ibuf, *obuf;
1801 int ret = 0, nbuf;
1802 bool input_wakeup = false;
1803
1804
1805retry:
1806 ret = ipipe_prep(ipipe, flags);
1807 if (ret)
1808 return ret;
1809
1810 ret = opipe_prep(opipe, flags);
1811 if (ret)
1812 return ret;
1813
1814 /*
1815 * Potential ABBA deadlock, work around it by ordering lock
1816 * grabbing by pipe info address. Otherwise two different processes
1817 * could deadlock (one doing tee from A -> B, the other from B -> A).
1818 */
1819 pipe_double_lock(ipipe, opipe);
1820
1821 do {
1822 if (!opipe->readers) {
1823 send_sig(SIGPIPE, current, 0);
1824 if (!ret)
1825 ret = -EPIPE;
1826 break;
1827 }
1828
1829 if (!ipipe->nrbufs && !ipipe->writers)
1830 break;
1831
1832 /*
1833 * Cannot make any progress, because either the input
1834 * pipe is empty or the output pipe is full.
1835 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001836 if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001837 /* Already processed some buffers, break */
1838 if (ret)
1839 break;
1840
1841 if (flags & SPLICE_F_NONBLOCK) {
1842 ret = -EAGAIN;
1843 break;
1844 }
1845
1846 /*
1847 * We raced with another reader/writer and haven't
1848 * managed to process any buffers. A zero return
1849 * value means EOF, so retry instead.
1850 */
1851 pipe_unlock(ipipe);
1852 pipe_unlock(opipe);
1853 goto retry;
1854 }
1855
1856 ibuf = ipipe->bufs + ipipe->curbuf;
Jens Axboe35f3d142010-05-20 10:43:18 +02001857 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001858 obuf = opipe->bufs + nbuf;
1859
1860 if (len >= ibuf->len) {
1861 /*
1862 * Simply move the whole buffer from ipipe to opipe
1863 */
1864 *obuf = *ibuf;
1865 ibuf->ops = NULL;
1866 opipe->nrbufs++;
Jens Axboe35f3d142010-05-20 10:43:18 +02001867 ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001868 ipipe->nrbufs--;
1869 input_wakeup = true;
1870 } else {
1871 /*
1872 * Get a reference to this pipe buffer,
1873 * so we can copy the contents over.
1874 */
1875 ibuf->ops->get(ipipe, ibuf);
1876 *obuf = *ibuf;
1877
1878 /*
1879 * Don't inherit the gift flag, we need to
1880 * prevent multiple steals of this page.
1881 */
1882 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1883
1884 obuf->len = len;
1885 opipe->nrbufs++;
1886 ibuf->offset += obuf->len;
1887 ibuf->len -= obuf->len;
1888 }
1889 ret += obuf->len;
1890 len -= obuf->len;
1891 } while (len);
1892
1893 pipe_unlock(ipipe);
1894 pipe_unlock(opipe);
1895
1896 /*
1897 * If we put data in the output pipe, wakeup any potential readers.
1898 */
Namhyung Kim825cdcb2011-05-23 19:58:53 +02001899 if (ret > 0)
1900 wakeup_pipe_readers(opipe);
1901
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02001902 if (input_wakeup)
1903 wakeup_pipe_writers(ipipe);
1904
1905 return ret;
1906}
1907
1908/*
Jens Axboe70524492006-04-11 15:51:17 +02001909 * Link contents of ipipe to opipe.
1910 */
1911static int link_pipe(struct pipe_inode_info *ipipe,
1912 struct pipe_inode_info *opipe,
1913 size_t len, unsigned int flags)
1914{
1915 struct pipe_buffer *ibuf, *obuf;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001916 int ret = 0, i = 0, nbuf;
Jens Axboe70524492006-04-11 15:51:17 +02001917
1918 /*
1919 * Potential ABBA deadlock, work around it by ordering lock
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001920 * grabbing by pipe info address. Otherwise two different processes
Jens Axboe70524492006-04-11 15:51:17 +02001921 * could deadlock (one doing tee from A -> B, the other from B -> A).
1922 */
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001923 pipe_double_lock(ipipe, opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001924
Jens Axboeaadd06e2006-07-10 11:00:01 +02001925 do {
Jens Axboe70524492006-04-11 15:51:17 +02001926 if (!opipe->readers) {
1927 send_sig(SIGPIPE, current, 0);
1928 if (!ret)
1929 ret = -EPIPE;
1930 break;
1931 }
Jens Axboe70524492006-04-11 15:51:17 +02001932
1933 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001934 * If we have iterated all input buffers or ran out of
1935 * output room, break.
Jens Axboe70524492006-04-11 15:51:17 +02001936 */
Jens Axboe35f3d142010-05-20 10:43:18 +02001937 if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
Jens Axboe70524492006-04-11 15:51:17 +02001938 break;
Jens Axboeaadd06e2006-07-10 11:00:01 +02001939
Jens Axboe35f3d142010-05-20 10:43:18 +02001940 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
1941 nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001942
Jens Axboe2a27250e2006-04-19 15:56:40 +02001943 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02001944 * Get a reference to this pipe buffer,
1945 * so we can copy the contents over.
Jens Axboe2a27250e2006-04-19 15:56:40 +02001946 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02001947 ibuf->ops->get(ipipe, ibuf);
Jens Axboe70524492006-04-11 15:51:17 +02001948
Jens Axboeaadd06e2006-07-10 11:00:01 +02001949 obuf = opipe->bufs + nbuf;
1950 *obuf = *ibuf;
Jens Axboe70524492006-04-11 15:51:17 +02001951
Jens Axboeaadd06e2006-07-10 11:00:01 +02001952 /*
1953 * Don't inherit the gift flag, we need to
1954 * prevent multiple steals of this page.
1955 */
1956 obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
1957
1958 if (obuf->len > len)
1959 obuf->len = len;
1960
1961 opipe->nrbufs++;
1962 ret += obuf->len;
1963 len -= obuf->len;
1964 i++;
1965 } while (len);
Jens Axboe70524492006-04-11 15:51:17 +02001966
Jens Axboe02cf01a2008-02-20 10:34:51 +01001967 /*
1968 * return EAGAIN if we have the potential of some data in the
1969 * future, otherwise just return 0
1970 */
1971 if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
1972 ret = -EAGAIN;
1973
Miklos Szeredi61e0d472009-04-14 19:48:41 +02001974 pipe_unlock(ipipe);
1975 pipe_unlock(opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001976
Jens Axboeaadd06e2006-07-10 11:00:01 +02001977 /*
1978 * If we put data in the output pipe, wakeup any potential readers.
1979 */
Namhyung Kim825cdcb2011-05-23 19:58:53 +02001980 if (ret > 0)
1981 wakeup_pipe_readers(opipe);
Jens Axboe70524492006-04-11 15:51:17 +02001982
1983 return ret;
1984}
1985
1986/*
1987 * This is a tee(1) implementation that works on pipes. It doesn't copy
1988 * any data, it simply references the 'in' pages on the 'out' pipe.
1989 * The 'flags' used are the SPLICE_F_* variants, currently the only
1990 * applicable one is SPLICE_F_NONBLOCK.
1991 */
1992static long do_tee(struct file *in, struct file *out, size_t len,
1993 unsigned int flags)
1994{
Linus Torvalds71993e62010-11-28 13:56:09 -08001995 struct pipe_inode_info *ipipe = get_pipe_info(in);
1996 struct pipe_inode_info *opipe = get_pipe_info(out);
Jens Axboeaadd06e2006-07-10 11:00:01 +02001997 int ret = -EINVAL;
Jens Axboe70524492006-04-11 15:51:17 +02001998
1999 /*
Jens Axboeaadd06e2006-07-10 11:00:01 +02002000 * Duplicate the contents of ipipe to opipe without actually
2001 * copying the data.
Jens Axboe70524492006-04-11 15:51:17 +02002002 */
Jens Axboeaadd06e2006-07-10 11:00:01 +02002003 if (ipipe && opipe && ipipe != opipe) {
2004 /*
2005 * Keep going, unless we encounter an error. The ipipe/opipe
2006 * ordering doesn't really matter.
2007 */
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02002008 ret = ipipe_prep(ipipe, flags);
Jens Axboeaadd06e2006-07-10 11:00:01 +02002009 if (!ret) {
Miklos Szeredi7c77f0b2009-05-07 15:37:35 +02002010 ret = opipe_prep(opipe, flags);
Jens Axboe02cf01a2008-02-20 10:34:51 +01002011 if (!ret)
Jens Axboeaadd06e2006-07-10 11:00:01 +02002012 ret = link_pipe(ipipe, opipe, len, flags);
Jens Axboeaadd06e2006-07-10 11:00:01 +02002013 }
2014 }
Jens Axboe70524492006-04-11 15:51:17 +02002015
Jens Axboeaadd06e2006-07-10 11:00:01 +02002016 return ret;
Jens Axboe70524492006-04-11 15:51:17 +02002017}
2018
Heiko Carstens836f92a2009-01-14 14:14:33 +01002019SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
Jens Axboe70524492006-04-11 15:51:17 +02002020{
Al Viro2903ff02012-08-28 12:52:22 -04002021 struct fd in;
2022 int error;
Jens Axboe70524492006-04-11 15:51:17 +02002023
2024 if (unlikely(!len))
2025 return 0;
2026
2027 error = -EBADF;
Al Viro2903ff02012-08-28 12:52:22 -04002028 in = fdget(fdin);
2029 if (in.file) {
2030 if (in.file->f_mode & FMODE_READ) {
2031 struct fd out = fdget(fdout);
2032 if (out.file) {
2033 if (out.file->f_mode & FMODE_WRITE)
2034 error = do_tee(in.file, out.file,
2035 len, flags);
2036 fdput(out);
Jens Axboe70524492006-04-11 15:51:17 +02002037 }
2038 }
Al Viro2903ff02012-08-28 12:52:22 -04002039 fdput(in);
Jens Axboe70524492006-04-11 15:51:17 +02002040 }
2041
2042 return error;
2043}