2 * "splice": joining two ropes together by interweaving their strands.
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.
8 * The traditional unix read/write is extended with a "splice()" operation
9 * that transfers data buffers to or from a pipe buffer.
11 * Named by Larry McVoy, original implementation from Linus, extended by
12 * Jens to support splicing to files, network, direct splicing, etc and
13 * fixing lots of bugs.
15 * Copyright (C) 2005-2006 Jens Axboe <axboe@suse.de>
16 * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
17 * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
21 #include <linux/file.h>
22 #include <linux/pagemap.h>
23 #include <linux/pipe_fs_i.h>
24 #include <linux/mm_inline.h>
25 #include <linux/swap.h>
26 #include <linux/writeback.h>
27 #include <linux/buffer_head.h>
28 #include <linux/module.h>
29 #include <linux/syscalls.h>
32 * Passed to the actors
35 unsigned int len, total_len; /* current and remaining length */
36 unsigned int flags; /* splice flags */
37 struct file *file; /* file to read/write */
38 loff_t pos; /* file position */
42 * Attempt to steal a page from a pipe buffer. This should perhaps go into
43 * a vm helper function, it's already simplified quite a bit by the
44 * addition of remove_mapping(). If success is returned, the caller may
45 * attempt to reuse this page for another destination.
47 static int page_cache_pipe_buf_steal(struct pipe_inode_info *info,
48 struct pipe_buffer *buf)
50 struct page *page = buf->page;
51 struct address_space *mapping = page_mapping(page);
53 WARN_ON(!PageLocked(page));
54 WARN_ON(!PageUptodate(page));
57 * At least for ext2 with nobh option, we need to wait on writeback
58 * completing on this page, since we'll remove it from the pagecache.
59 * Otherwise truncate wont wait on the page, allowing the disk
60 * blocks to be reused by someone else before we actually wrote our
61 * data to them. fs corruption ensues.
63 wait_on_page_writeback(page);
65 if (PagePrivate(page))
66 try_to_release_page(page, mapping_gfp_mask(mapping));
68 if (!remove_mapping(mapping, page))
71 buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
75 static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
76 struct pipe_buffer *buf)
78 page_cache_release(buf->page);
80 buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU);
83 static void *page_cache_pipe_buf_map(struct file *file,
84 struct pipe_inode_info *info,
85 struct pipe_buffer *buf)
87 struct page *page = buf->page;
90 if (!PageUptodate(page)) {
94 * Page got truncated/unhashed. This will cause a 0-byte
95 * splice, if this is the first page.
103 * Uh oh, read-error from disk.
105 if (!PageUptodate(page)) {
111 * Page is ok afterall, fall through to mapping.
122 static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
123 struct pipe_buffer *buf)
128 static void page_cache_pipe_buf_get(struct pipe_inode_info *info,
129 struct pipe_buffer *buf)
131 page_cache_get(buf->page);
134 static struct pipe_buf_operations page_cache_pipe_buf_ops = {
136 .map = page_cache_pipe_buf_map,
137 .unmap = page_cache_pipe_buf_unmap,
138 .release = page_cache_pipe_buf_release,
139 .steal = page_cache_pipe_buf_steal,
140 .get = page_cache_pipe_buf_get,
144 * Pipe output worker. This sets up our pipe format with the page cache
145 * pipe buffer operations. Otherwise very similar to the regular pipe_writev().
147 static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
148 int nr_pages, unsigned long len,
149 unsigned int offset, unsigned int flags)
151 int ret, do_wakeup, i;
158 mutex_lock(&pipe->inode->i_mutex);
161 if (!pipe->readers) {
162 send_sig(SIGPIPE, current, 0);
168 if (pipe->nrbufs < PIPE_BUFFERS) {
169 int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
170 struct pipe_buffer *buf = pipe->bufs + newbuf;
171 struct page *page = pages[i++];
172 unsigned long this_len;
174 this_len = PAGE_CACHE_SIZE - offset;
179 buf->offset = offset;
181 buf->ops = &page_cache_pipe_buf_ops;
193 if (pipe->nrbufs < PIPE_BUFFERS)
199 if (flags & SPLICE_F_NONBLOCK) {
205 if (signal_pending(current)) {
213 if (waitqueue_active(&pipe->wait))
214 wake_up_interruptible_sync(&pipe->wait);
215 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
219 pipe->waiting_writers++;
221 pipe->waiting_writers--;
225 mutex_unlock(&pipe->inode->i_mutex);
229 if (waitqueue_active(&pipe->wait))
230 wake_up_interruptible(&pipe->wait);
231 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
235 page_cache_release(pages[i++]);
241 __generic_file_splice_read(struct file *in, loff_t *ppos,
242 struct pipe_inode_info *pipe, size_t len,
245 struct address_space *mapping = in->f_mapping;
246 unsigned int loff, offset, nr_pages;
247 struct page *pages[PIPE_BUFFERS];
249 pgoff_t index, end_index;
254 index = *ppos >> PAGE_CACHE_SHIFT;
255 loff = offset = *ppos & ~PAGE_CACHE_MASK;
256 nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
258 if (nr_pages > PIPE_BUFFERS)
259 nr_pages = PIPE_BUFFERS;
262 * Initiate read-ahead on this page range. however, don't call into
263 * read-ahead if this is a non-zero offset (we are likely doing small
264 * chunk splice and the page is already there) for a single page.
266 if (!offset || nr_pages > 1)
267 do_page_cache_readahead(mapping, in, index, nr_pages);
270 * Now fill in the holes:
274 for (i = 0; i < nr_pages; i++, index++) {
277 * lookup the page for this index
279 page = find_get_page(mapping, index);
282 * page didn't exist, allocate one
284 page = page_cache_alloc_cold(mapping);
288 error = add_to_page_cache_lru(page, mapping, index,
289 mapping_gfp_mask(mapping));
290 if (unlikely(error)) {
291 page_cache_release(page);
299 * If the page isn't uptodate, we may need to start io on it
301 if (!PageUptodate(page)) {
303 * If in nonblock mode then dont block on waiting
304 * for an in-flight io page
306 if (flags & SPLICE_F_NONBLOCK)
312 * page was truncated, stop here. if this isn't the
313 * first page, we'll just complete what we already
316 if (!page->mapping) {
318 page_cache_release(page);
322 * page was already under io and is now done, great
324 if (PageUptodate(page)) {
331 * need to read in the page
333 error = mapping->a_ops->readpage(in, page);
335 if (unlikely(error)) {
336 page_cache_release(page);
337 if (error == AOP_TRUNCATED_PAGE)
343 * i_size must be checked after ->readpage().
345 isize = i_size_read(mapping->host);
346 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
347 if (unlikely(!isize || index > end_index)) {
348 page_cache_release(page);
353 * if this is the last page, see if we need to shrink
354 * the length and stop
356 if (end_index == index) {
357 loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
358 if (bytes + loff > isize) {
359 page_cache_release(page);
363 * force quit after adding this page
370 bytes += PAGE_CACHE_SIZE - loff;
375 return move_to_pipe(pipe, pages, i, bytes, offset, flags);
381 * generic_file_splice_read - splice data from file to a pipe
382 * @in: file to splice from
383 * @pipe: pipe to splice to
384 * @len: number of bytes to splice
385 * @flags: splice modifier flags
387 * Will read pages from given file and fill them into a pipe.
389 ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
390 struct pipe_inode_info *pipe, size_t len,
400 ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
407 if (flags & SPLICE_F_NONBLOCK) {
424 EXPORT_SYMBOL(generic_file_splice_read);
427 * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
430 static int pipe_to_sendpage(struct pipe_inode_info *info,
431 struct pipe_buffer *buf, struct splice_desc *sd)
433 struct file *file = sd->file;
434 loff_t pos = sd->pos;
441 * Sub-optimal, but we are limited by the pipe ->map. We don't
442 * need a kmap'ed buffer here, we just want to make sure we
443 * have the page pinned if the pipe page originates from the
446 ptr = buf->ops->map(file, info, buf);
450 offset = pos & ~PAGE_CACHE_MASK;
451 more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
453 ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more);
455 buf->ops->unmap(info, buf);
463 * This is a little more tricky than the file -> pipe splicing. There are
464 * basically three cases:
466 * - Destination page already exists in the address space and there
467 * are users of it. For that case we have no other option that
468 * copying the data. Tough luck.
469 * - Destination page already exists in the address space, but there
470 * are no users of it. Make sure it's uptodate, then drop it. Fall
471 * through to last case.
472 * - Destination page does not exist, we can add the pipe page to
473 * the page cache and avoid the copy.
475 * If asked to move pages to the output file (SPLICE_F_MOVE is set in
476 * sd->flags), we attempt to migrate pages from the pipe to the output
477 * file address space page cache. This is possible if no one else has
478 * the pipe page referenced outside of the pipe and page cache. If
479 * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
480 * a new page in the output file page cache and fill/dirty that.
482 static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
483 struct splice_desc *sd)
485 struct file *file = sd->file;
486 struct address_space *mapping = file->f_mapping;
487 gfp_t gfp_mask = mapping_gfp_mask(mapping);
495 * make sure the data in this buffer is uptodate
497 src = buf->ops->map(file, info, buf);
501 index = sd->pos >> PAGE_CACHE_SHIFT;
502 offset = sd->pos & ~PAGE_CACHE_MASK;
505 * Reuse buf page, if SPLICE_F_MOVE is set.
507 if (sd->flags & SPLICE_F_MOVE) {
509 * If steal succeeds, buf->page is now pruned from the vm
510 * side (LRU and page cache) and we can reuse it.
512 if (buf->ops->steal(info, buf))
516 * this will also set the page locked
519 if (add_to_page_cache(page, mapping, index, gfp_mask))
522 if (!(buf->flags & PIPE_BUF_FLAG_LRU))
527 page = find_or_create_page(mapping, index, gfp_mask);
532 * If the page is uptodate, it is also locked. If it isn't
533 * uptodate, we can mark it uptodate if we are filling the
534 * full page. Otherwise we need to read it in first...
536 if (!PageUptodate(page)) {
537 if (sd->len < PAGE_CACHE_SIZE) {
538 ret = mapping->a_ops->readpage(file, page);
544 if (!PageUptodate(page)) {
546 * Page got invalidated, repeat.
548 if (!page->mapping) {
550 page_cache_release(page);
557 WARN_ON(!PageLocked(page));
558 SetPageUptodate(page);
563 ret = mapping->a_ops->prepare_write(file, page, 0, sd->len);
564 if (ret == AOP_TRUNCATED_PAGE) {
565 page_cache_release(page);
570 if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
571 char *dst = kmap_atomic(page, KM_USER0);
573 memcpy(dst + offset, src + buf->offset, sd->len);
574 flush_dcache_page(page);
575 kunmap_atomic(dst, KM_USER0);
578 ret = mapping->a_ops->commit_write(file, page, 0, sd->len);
579 if (ret == AOP_TRUNCATED_PAGE) {
580 page_cache_release(page);
585 mark_page_accessed(page);
586 balance_dirty_pages_ratelimited(mapping);
588 if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
589 page_cache_release(page);
593 buf->ops->unmap(info, buf);
597 typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
598 struct splice_desc *);
601 * Pipe input worker. Most of this logic works like a regular pipe, the
602 * key here is the 'actor' worker passed in that actually moves the data
603 * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
605 static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
606 loff_t *ppos, size_t len, unsigned int flags,
609 int ret, do_wakeup, err;
610 struct splice_desc sd;
621 mutex_lock(&pipe->inode->i_mutex);
625 struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
626 struct pipe_buf_operations *ops = buf->ops;
629 if (sd.len > sd.total_len)
630 sd.len = sd.total_len;
632 err = actor(pipe, buf, &sd);
634 if (!ret && err != -ENODATA)
641 buf->offset += sd.len;
646 ops->release(pipe, buf);
647 pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
654 sd.total_len -= sd.len;
663 if (!pipe->waiting_writers) {
668 if (flags & SPLICE_F_NONBLOCK) {
674 if (signal_pending(current)) {
682 if (waitqueue_active(&pipe->wait))
683 wake_up_interruptible_sync(&pipe->wait);
684 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
692 mutex_unlock(&pipe->inode->i_mutex);
696 if (waitqueue_active(&pipe->wait))
697 wake_up_interruptible(&pipe->wait);
698 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
705 * generic_file_splice_write - splice data from a pipe to a file
707 * @out: file to write to
708 * @len: number of bytes to splice
709 * @flags: splice modifier flags
711 * Will either move or copy pages (determined by @flags options) from
712 * the given pipe inode to the given file.
716 generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
717 loff_t *ppos, size_t len, unsigned int flags)
719 struct address_space *mapping = out->f_mapping;
722 ret = move_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
725 * If file or inode is SYNC and we actually wrote some data, sync it.
727 if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host))
729 struct inode *inode = mapping->host;
732 mutex_lock(&inode->i_mutex);
733 err = generic_osync_inode(mapping->host, mapping,
734 OSYNC_METADATA|OSYNC_DATA);
735 mutex_unlock(&inode->i_mutex);
744 EXPORT_SYMBOL(generic_file_splice_write);
747 * generic_splice_sendpage - splice data from a pipe to a socket
749 * @out: socket to write to
750 * @len: number of bytes to splice
751 * @flags: splice modifier flags
753 * Will send @len bytes from the pipe to a network socket. No data copying
757 ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
758 loff_t *ppos, size_t len, unsigned int flags)
760 return move_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
763 EXPORT_SYMBOL(generic_splice_sendpage);
766 * Attempt to initiate a splice from pipe to file.
768 static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
769 loff_t *ppos, size_t len, unsigned int flags)
773 if (unlikely(!out->f_op || !out->f_op->splice_write))
776 if (unlikely(!(out->f_mode & FMODE_WRITE)))
779 ret = rw_verify_area(WRITE, out, ppos, len);
780 if (unlikely(ret < 0))
783 return out->f_op->splice_write(pipe, out, ppos, len, flags);
787 * Attempt to initiate a splice from a file to a pipe.
789 static long do_splice_to(struct file *in, loff_t *ppos,
790 struct pipe_inode_info *pipe, size_t len,
796 if (unlikely(!in->f_op || !in->f_op->splice_read))
799 if (unlikely(!(in->f_mode & FMODE_READ)))
802 ret = rw_verify_area(READ, in, ppos, len);
803 if (unlikely(ret < 0))
806 isize = i_size_read(in->f_mapping->host);
807 if (unlikely(*ppos >= isize))
810 left = isize - *ppos;
811 if (unlikely(left < len))
814 return in->f_op->splice_read(in, ppos, pipe, len, flags);
817 long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
818 size_t len, unsigned int flags)
820 struct pipe_inode_info *pipe;
827 * We require the input being a regular file, as we don't want to
828 * randomly drop data for eg socket -> socket splicing. Use the
829 * piped splicing for that!
831 i_mode = in->f_dentry->d_inode->i_mode;
832 if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
836 * neither in nor out is a pipe, setup an internal pipe attached to
837 * 'out' and transfer the wanted data from 'in' to 'out' through that
839 pipe = current->splice_pipe;
840 if (unlikely(!pipe)) {
841 pipe = alloc_pipe_info(NULL);
846 * We don't have an immediate reader, but we'll read the stuff
847 * out of the pipe right after the move_to_pipe(). So set
848 * PIPE_READERS appropriately.
852 current->splice_pipe = pipe;
863 size_t read_len, max_read_len;
866 * Do at most PIPE_BUFFERS pages worth of transfer:
868 max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
870 ret = do_splice_to(in, ppos, pipe, max_read_len, flags);
871 if (unlikely(ret < 0))
877 * NOTE: nonblocking mode only applies to the input. We
878 * must not do the output in nonblocking mode as then we
879 * could get stuck data in the internal pipe:
881 ret = do_splice_from(pipe, out, &out_off, read_len,
882 flags & ~SPLICE_F_NONBLOCK);
883 if (unlikely(ret < 0))
890 * In nonblocking mode, if we got back a short read then
891 * that was due to either an IO error or due to the
892 * pagecache entry not being there. In the IO error case
893 * the _next_ splice attempt will produce a clean IO error
894 * return value (not a short read), so in both cases it's
895 * correct to break out of the loop here:
897 if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
901 pipe->nrbufs = pipe->curbuf = 0;
907 * If we did an incomplete transfer we must release
908 * the pipe buffers in question:
910 for (i = 0; i < PIPE_BUFFERS; i++) {
911 struct pipe_buffer *buf = pipe->bufs + i;
914 buf->ops->release(pipe, buf);
918 pipe->nrbufs = pipe->curbuf = 0;
921 * If we transferred some data, return the number of bytes:
929 EXPORT_SYMBOL(do_splice_direct);
932 * Determine where to splice to/from.
934 static long do_splice(struct file *in, loff_t __user *off_in,
935 struct file *out, loff_t __user *off_out,
936 size_t len, unsigned int flags)
938 struct pipe_inode_info *pipe;
941 pipe = in->f_dentry->d_inode->i_pipe;
946 if (out->f_op->llseek == no_llseek)
948 if (copy_from_user(&offset, off_out, sizeof(loff_t)))
954 return do_splice_from(pipe, out, off, len, flags);
957 pipe = out->f_dentry->d_inode->i_pipe;
962 if (in->f_op->llseek == no_llseek)
964 if (copy_from_user(&offset, off_in, sizeof(loff_t)))
970 return do_splice_to(in, off, pipe, len, flags);
976 asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
977 int fd_out, loff_t __user *off_out,
978 size_t len, unsigned int flags)
981 struct file *in, *out;
982 int fput_in, fput_out;
988 in = fget_light(fd_in, &fput_in);
990 if (in->f_mode & FMODE_READ) {
991 out = fget_light(fd_out, &fput_out);
993 if (out->f_mode & FMODE_WRITE)
994 error = do_splice(in, off_in,
997 fput_light(out, fput_out);
1001 fput_light(in, fput_in);
1008 * Link contents of ipipe to opipe.
1010 static int link_pipe(struct pipe_inode_info *ipipe,
1011 struct pipe_inode_info *opipe,
1012 size_t len, unsigned int flags)
1014 struct pipe_buffer *ibuf, *obuf;
1015 int ret = 0, do_wakeup = 0, i;
1018 * Potential ABBA deadlock, work around it by ordering lock
1019 * grabbing by inode address. Otherwise two different processes
1020 * could deadlock (one doing tee from A -> B, the other from B -> A).
1022 if (ipipe->inode < opipe->inode) {
1023 mutex_lock(&ipipe->inode->i_mutex);
1024 mutex_lock(&opipe->inode->i_mutex);
1026 mutex_lock(&opipe->inode->i_mutex);
1027 mutex_lock(&ipipe->inode->i_mutex);
1031 if (!opipe->readers) {
1032 send_sig(SIGPIPE, current, 0);
1037 if (ipipe->nrbufs - i) {
1038 ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
1041 * If we have room, fill this buffer
1043 if (opipe->nrbufs < PIPE_BUFFERS) {
1044 int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1);
1047 * Get a reference to this pipe buffer,
1048 * so we can copy the contents over.
1050 ibuf->ops->get(ipipe, ibuf);
1052 obuf = opipe->bufs + nbuf;
1055 if (obuf->len > len)
1065 if (opipe->nrbufs < PIPE_BUFFERS)
1070 * We have input available, but no output room.
1071 * If we already copied data, return that.
1073 if (flags & SPLICE_F_NONBLOCK) {
1078 if (signal_pending(current)) {
1085 if (waitqueue_active(&opipe->wait))
1086 wake_up_interruptible(&opipe->wait);
1087 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1091 opipe->waiting_writers++;
1093 opipe->waiting_writers--;
1098 * No input buffers, do the usual checks for available
1099 * writers and blocking and wait if necessary
1101 if (!ipipe->writers)
1103 if (!ipipe->waiting_writers) {
1107 if (flags & SPLICE_F_NONBLOCK) {
1112 if (signal_pending(current)) {
1118 if (waitqueue_active(&ipipe->wait))
1119 wake_up_interruptible_sync(&ipipe->wait);
1120 kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT);
1125 mutex_unlock(&ipipe->inode->i_mutex);
1126 mutex_unlock(&opipe->inode->i_mutex);
1130 if (waitqueue_active(&opipe->wait))
1131 wake_up_interruptible(&opipe->wait);
1132 kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
1139 * This is a tee(1) implementation that works on pipes. It doesn't copy
1140 * any data, it simply references the 'in' pages on the 'out' pipe.
1141 * The 'flags' used are the SPLICE_F_* variants, currently the only
1142 * applicable one is SPLICE_F_NONBLOCK.
1144 static long do_tee(struct file *in, struct file *out, size_t len,
1147 struct pipe_inode_info *ipipe = in->f_dentry->d_inode->i_pipe;
1148 struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
1151 * Link ipipe to the two output pipes, consuming as we go along.
1154 return link_pipe(ipipe, opipe, len, flags);
1159 asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
1168 in = fget_light(fdin, &fput_in);
1170 if (in->f_mode & FMODE_READ) {
1172 struct file *out = fget_light(fdout, &fput_out);
1175 if (out->f_mode & FMODE_WRITE)
1176 error = do_tee(in, out, len, flags);
1177 fput_light(out, fput_out);
1180 fput_light(in, fput_in);