pipe: fix check in "set size" fcntl
[linux-2.6.git] / fs / pipe.c
1 /*
2  *  linux/fs/pipe.c
3  *
4  *  Copyright (C) 1991, 1992, 1999  Linus Torvalds
5  */
6
7 #include <linux/mm.h>
8 #include <linux/file.h>
9 #include <linux/poll.h>
10 #include <linux/slab.h>
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/fs.h>
14 #include <linux/log2.h>
15 #include <linux/mount.h>
16 #include <linux/pipe_fs_i.h>
17 #include <linux/uio.h>
18 #include <linux/highmem.h>
19 #include <linux/pagemap.h>
20 #include <linux/audit.h>
21 #include <linux/syscalls.h>
22 #include <linux/fcntl.h>
23
24 #include <asm/uaccess.h>
25 #include <asm/ioctls.h>
26
27 /*
28  * The max size that a non-root user is allowed to grow the pipe. Can
29  * be set by root in /proc/sys/fs/pipe-max-size
30  */
31 unsigned int pipe_max_size = 1048576;
32
33 /*
34  * Minimum pipe size, as required by POSIX
35  */
36 unsigned int pipe_min_size = PAGE_SIZE;
37
38 /*
39  * We use a start+len construction, which provides full use of the 
40  * allocated memory.
41  * -- Florian Coosmann (FGC)
42  * 
43  * Reads with count = 0 should always return 0.
44  * -- Julian Bradfield 1999-06-07.
45  *
46  * FIFOs and Pipes now generate SIGIO for both readers and writers.
47  * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
48  *
49  * pipe_read & write cleanup
50  * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
51  */
52
53 static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
54 {
55         if (pipe->inode)
56                 mutex_lock_nested(&pipe->inode->i_mutex, subclass);
57 }
58
59 void pipe_lock(struct pipe_inode_info *pipe)
60 {
61         /*
62          * pipe_lock() nests non-pipe inode locks (for writing to a file)
63          */
64         pipe_lock_nested(pipe, I_MUTEX_PARENT);
65 }
66 EXPORT_SYMBOL(pipe_lock);
67
68 void pipe_unlock(struct pipe_inode_info *pipe)
69 {
70         if (pipe->inode)
71                 mutex_unlock(&pipe->inode->i_mutex);
72 }
73 EXPORT_SYMBOL(pipe_unlock);
74
75 void pipe_double_lock(struct pipe_inode_info *pipe1,
76                       struct pipe_inode_info *pipe2)
77 {
78         BUG_ON(pipe1 == pipe2);
79
80         if (pipe1 < pipe2) {
81                 pipe_lock_nested(pipe1, I_MUTEX_PARENT);
82                 pipe_lock_nested(pipe2, I_MUTEX_CHILD);
83         } else {
84                 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
85                 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
86         }
87 }
88
89 /* Drop the inode semaphore and wait for a pipe event, atomically */
90 void pipe_wait(struct pipe_inode_info *pipe)
91 {
92         DEFINE_WAIT(wait);
93
94         /*
95          * Pipes are system-local resources, so sleeping on them
96          * is considered a noninteractive wait:
97          */
98         prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
99         pipe_unlock(pipe);
100         schedule();
101         finish_wait(&pipe->wait, &wait);
102         pipe_lock(pipe);
103 }
104
105 static int
106 pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
107                         int atomic)
108 {
109         unsigned long copy;
110
111         while (len > 0) {
112                 while (!iov->iov_len)
113                         iov++;
114                 copy = min_t(unsigned long, len, iov->iov_len);
115
116                 if (atomic) {
117                         if (__copy_from_user_inatomic(to, iov->iov_base, copy))
118                                 return -EFAULT;
119                 } else {
120                         if (copy_from_user(to, iov->iov_base, copy))
121                                 return -EFAULT;
122                 }
123                 to += copy;
124                 len -= copy;
125                 iov->iov_base += copy;
126                 iov->iov_len -= copy;
127         }
128         return 0;
129 }
130
131 static int
132 pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len,
133                       int atomic)
134 {
135         unsigned long copy;
136
137         while (len > 0) {
138                 while (!iov->iov_len)
139                         iov++;
140                 copy = min_t(unsigned long, len, iov->iov_len);
141
142                 if (atomic) {
143                         if (__copy_to_user_inatomic(iov->iov_base, from, copy))
144                                 return -EFAULT;
145                 } else {
146                         if (copy_to_user(iov->iov_base, from, copy))
147                                 return -EFAULT;
148                 }
149                 from += copy;
150                 len -= copy;
151                 iov->iov_base += copy;
152                 iov->iov_len -= copy;
153         }
154         return 0;
155 }
156
157 /*
158  * Attempt to pre-fault in the user memory, so we can use atomic copies.
159  * Returns the number of bytes not faulted in.
160  */
161 static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
162 {
163         while (!iov->iov_len)
164                 iov++;
165
166         while (len > 0) {
167                 unsigned long this_len;
168
169                 this_len = min_t(unsigned long, len, iov->iov_len);
170                 if (fault_in_pages_writeable(iov->iov_base, this_len))
171                         break;
172
173                 len -= this_len;
174                 iov++;
175         }
176
177         return len;
178 }
179
180 /*
181  * Pre-fault in the user memory, so we can use atomic copies.
182  */
183 static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
184 {
185         while (!iov->iov_len)
186                 iov++;
187
188         while (len > 0) {
189                 unsigned long this_len;
190
191                 this_len = min_t(unsigned long, len, iov->iov_len);
192                 fault_in_pages_readable(iov->iov_base, this_len);
193                 len -= this_len;
194                 iov++;
195         }
196 }
197
198 static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
199                                   struct pipe_buffer *buf)
200 {
201         struct page *page = buf->page;
202
203         /*
204          * If nobody else uses this page, and we don't already have a
205          * temporary page, let's keep track of it as a one-deep
206          * allocation cache. (Otherwise just release our reference to it)
207          */
208         if (page_count(page) == 1 && !pipe->tmp_page)
209                 pipe->tmp_page = page;
210         else
211                 page_cache_release(page);
212 }
213
214 /**
215  * generic_pipe_buf_map - virtually map a pipe buffer
216  * @pipe:       the pipe that the buffer belongs to
217  * @buf:        the buffer that should be mapped
218  * @atomic:     whether to use an atomic map
219  *
220  * Description:
221  *      This function returns a kernel virtual address mapping for the
222  *      pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided
223  *      and the caller has to be careful not to fault before calling
224  *      the unmap function.
225  *
226  *      Note that this function occupies KM_USER0 if @atomic != 0.
227  */
228 void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
229                            struct pipe_buffer *buf, int atomic)
230 {
231         if (atomic) {
232                 buf->flags |= PIPE_BUF_FLAG_ATOMIC;
233                 return kmap_atomic(buf->page, KM_USER0);
234         }
235
236         return kmap(buf->page);
237 }
238 EXPORT_SYMBOL(generic_pipe_buf_map);
239
240 /**
241  * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer
242  * @pipe:       the pipe that the buffer belongs to
243  * @buf:        the buffer that should be unmapped
244  * @map_data:   the data that the mapping function returned
245  *
246  * Description:
247  *      This function undoes the mapping that ->map() provided.
248  */
249 void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
250                             struct pipe_buffer *buf, void *map_data)
251 {
252         if (buf->flags & PIPE_BUF_FLAG_ATOMIC) {
253                 buf->flags &= ~PIPE_BUF_FLAG_ATOMIC;
254                 kunmap_atomic(map_data, KM_USER0);
255         } else
256                 kunmap(buf->page);
257 }
258 EXPORT_SYMBOL(generic_pipe_buf_unmap);
259
260 /**
261  * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
262  * @pipe:       the pipe that the buffer belongs to
263  * @buf:        the buffer to attempt to steal
264  *
265  * Description:
266  *      This function attempts to steal the &struct page attached to
267  *      @buf. If successful, this function returns 0 and returns with
268  *      the page locked. The caller may then reuse the page for whatever
269  *      he wishes; the typical use is insertion into a different file
270  *      page cache.
271  */
272 int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
273                            struct pipe_buffer *buf)
274 {
275         struct page *page = buf->page;
276
277         /*
278          * A reference of one is golden, that means that the owner of this
279          * page is the only one holding a reference to it. lock the page
280          * and return OK.
281          */
282         if (page_count(page) == 1) {
283                 lock_page(page);
284                 return 0;
285         }
286
287         return 1;
288 }
289 EXPORT_SYMBOL(generic_pipe_buf_steal);
290
291 /**
292  * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
293  * @pipe:       the pipe that the buffer belongs to
294  * @buf:        the buffer to get a reference to
295  *
296  * Description:
297  *      This function grabs an extra reference to @buf. It's used in
298  *      in the tee() system call, when we duplicate the buffers in one
299  *      pipe into another.
300  */
301 void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
302 {
303         page_cache_get(buf->page);
304 }
305 EXPORT_SYMBOL(generic_pipe_buf_get);
306
307 /**
308  * generic_pipe_buf_confirm - verify contents of the pipe buffer
309  * @info:       the pipe that the buffer belongs to
310  * @buf:        the buffer to confirm
311  *
312  * Description:
313  *      This function does nothing, because the generic pipe code uses
314  *      pages that are always good when inserted into the pipe.
315  */
316 int generic_pipe_buf_confirm(struct pipe_inode_info *info,
317                              struct pipe_buffer *buf)
318 {
319         return 0;
320 }
321 EXPORT_SYMBOL(generic_pipe_buf_confirm);
322
323 /**
324  * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
325  * @pipe:       the pipe that the buffer belongs to
326  * @buf:        the buffer to put a reference to
327  *
328  * Description:
329  *      This function releases a reference to @buf.
330  */
331 void generic_pipe_buf_release(struct pipe_inode_info *pipe,
332                               struct pipe_buffer *buf)
333 {
334         page_cache_release(buf->page);
335 }
336 EXPORT_SYMBOL(generic_pipe_buf_release);
337
338 static const struct pipe_buf_operations anon_pipe_buf_ops = {
339         .can_merge = 1,
340         .map = generic_pipe_buf_map,
341         .unmap = generic_pipe_buf_unmap,
342         .confirm = generic_pipe_buf_confirm,
343         .release = anon_pipe_buf_release,
344         .steal = generic_pipe_buf_steal,
345         .get = generic_pipe_buf_get,
346 };
347
348 static ssize_t
349 pipe_read(struct kiocb *iocb, const struct iovec *_iov,
350            unsigned long nr_segs, loff_t pos)
351 {
352         struct file *filp = iocb->ki_filp;
353         struct inode *inode = filp->f_path.dentry->d_inode;
354         struct pipe_inode_info *pipe;
355         int do_wakeup;
356         ssize_t ret;
357         struct iovec *iov = (struct iovec *)_iov;
358         size_t total_len;
359
360         total_len = iov_length(iov, nr_segs);
361         /* Null read succeeds. */
362         if (unlikely(total_len == 0))
363                 return 0;
364
365         do_wakeup = 0;
366         ret = 0;
367         mutex_lock(&inode->i_mutex);
368         pipe = inode->i_pipe;
369         for (;;) {
370                 int bufs = pipe->nrbufs;
371                 if (bufs) {
372                         int curbuf = pipe->curbuf;
373                         struct pipe_buffer *buf = pipe->bufs + curbuf;
374                         const struct pipe_buf_operations *ops = buf->ops;
375                         void *addr;
376                         size_t chars = buf->len;
377                         int error, atomic;
378
379                         if (chars > total_len)
380                                 chars = total_len;
381
382                         error = ops->confirm(pipe, buf);
383                         if (error) {
384                                 if (!ret)
385                                         error = ret;
386                                 break;
387                         }
388
389                         atomic = !iov_fault_in_pages_write(iov, chars);
390 redo:
391                         addr = ops->map(pipe, buf, atomic);
392                         error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
393                         ops->unmap(pipe, buf, addr);
394                         if (unlikely(error)) {
395                                 /*
396                                  * Just retry with the slow path if we failed.
397                                  */
398                                 if (atomic) {
399                                         atomic = 0;
400                                         goto redo;
401                                 }
402                                 if (!ret)
403                                         ret = error;
404                                 break;
405                         }
406                         ret += chars;
407                         buf->offset += chars;
408                         buf->len -= chars;
409                         if (!buf->len) {
410                                 buf->ops = NULL;
411                                 ops->release(pipe, buf);
412                                 curbuf = (curbuf + 1) & (pipe->buffers - 1);
413                                 pipe->curbuf = curbuf;
414                                 pipe->nrbufs = --bufs;
415                                 do_wakeup = 1;
416                         }
417                         total_len -= chars;
418                         if (!total_len)
419                                 break;  /* common path: read succeeded */
420                 }
421                 if (bufs)       /* More to do? */
422                         continue;
423                 if (!pipe->writers)
424                         break;
425                 if (!pipe->waiting_writers) {
426                         /* syscall merging: Usually we must not sleep
427                          * if O_NONBLOCK is set, or if we got some data.
428                          * But if a writer sleeps in kernel space, then
429                          * we can wait for that data without violating POSIX.
430                          */
431                         if (ret)
432                                 break;
433                         if (filp->f_flags & O_NONBLOCK) {
434                                 ret = -EAGAIN;
435                                 break;
436                         }
437                 }
438                 if (signal_pending(current)) {
439                         if (!ret)
440                                 ret = -ERESTARTSYS;
441                         break;
442                 }
443                 if (do_wakeup) {
444                         wake_up_interruptible_sync(&pipe->wait);
445                         kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
446                 }
447                 pipe_wait(pipe);
448         }
449         mutex_unlock(&inode->i_mutex);
450
451         /* Signal writers asynchronously that there is more room. */
452         if (do_wakeup) {
453                 wake_up_interruptible_sync(&pipe->wait);
454                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
455         }
456         if (ret > 0)
457                 file_accessed(filp);
458         return ret;
459 }
460
461 static ssize_t
462 pipe_write(struct kiocb *iocb, const struct iovec *_iov,
463             unsigned long nr_segs, loff_t ppos)
464 {
465         struct file *filp = iocb->ki_filp;
466         struct inode *inode = filp->f_path.dentry->d_inode;
467         struct pipe_inode_info *pipe;
468         ssize_t ret;
469         int do_wakeup;
470         struct iovec *iov = (struct iovec *)_iov;
471         size_t total_len;
472         ssize_t chars;
473
474         total_len = iov_length(iov, nr_segs);
475         /* Null write succeeds. */
476         if (unlikely(total_len == 0))
477                 return 0;
478
479         do_wakeup = 0;
480         ret = 0;
481         mutex_lock(&inode->i_mutex);
482         pipe = inode->i_pipe;
483
484         if (!pipe->readers) {
485                 send_sig(SIGPIPE, current, 0);
486                 ret = -EPIPE;
487                 goto out;
488         }
489
490         /* We try to merge small writes */
491         chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
492         if (pipe->nrbufs && chars != 0) {
493                 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
494                                                         (pipe->buffers - 1);
495                 struct pipe_buffer *buf = pipe->bufs + lastbuf;
496                 const struct pipe_buf_operations *ops = buf->ops;
497                 int offset = buf->offset + buf->len;
498
499                 if (ops->can_merge && offset + chars <= PAGE_SIZE) {
500                         int error, atomic = 1;
501                         void *addr;
502
503                         error = ops->confirm(pipe, buf);
504                         if (error)
505                                 goto out;
506
507                         iov_fault_in_pages_read(iov, chars);
508 redo1:
509                         addr = ops->map(pipe, buf, atomic);
510                         error = pipe_iov_copy_from_user(offset + addr, iov,
511                                                         chars, atomic);
512                         ops->unmap(pipe, buf, addr);
513                         ret = error;
514                         do_wakeup = 1;
515                         if (error) {
516                                 if (atomic) {
517                                         atomic = 0;
518                                         goto redo1;
519                                 }
520                                 goto out;
521                         }
522                         buf->len += chars;
523                         total_len -= chars;
524                         ret = chars;
525                         if (!total_len)
526                                 goto out;
527                 }
528         }
529
530         for (;;) {
531                 int bufs;
532
533                 if (!pipe->readers) {
534                         send_sig(SIGPIPE, current, 0);
535                         if (!ret)
536                                 ret = -EPIPE;
537                         break;
538                 }
539                 bufs = pipe->nrbufs;
540                 if (bufs < pipe->buffers) {
541                         int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
542                         struct pipe_buffer *buf = pipe->bufs + newbuf;
543                         struct page *page = pipe->tmp_page;
544                         char *src;
545                         int error, atomic = 1;
546
547                         if (!page) {
548                                 page = alloc_page(GFP_HIGHUSER);
549                                 if (unlikely(!page)) {
550                                         ret = ret ? : -ENOMEM;
551                                         break;
552                                 }
553                                 pipe->tmp_page = page;
554                         }
555                         /* Always wake up, even if the copy fails. Otherwise
556                          * we lock up (O_NONBLOCK-)readers that sleep due to
557                          * syscall merging.
558                          * FIXME! Is this really true?
559                          */
560                         do_wakeup = 1;
561                         chars = PAGE_SIZE;
562                         if (chars > total_len)
563                                 chars = total_len;
564
565                         iov_fault_in_pages_read(iov, chars);
566 redo2:
567                         if (atomic)
568                                 src = kmap_atomic(page, KM_USER0);
569                         else
570                                 src = kmap(page);
571
572                         error = pipe_iov_copy_from_user(src, iov, chars,
573                                                         atomic);
574                         if (atomic)
575                                 kunmap_atomic(src, KM_USER0);
576                         else
577                                 kunmap(page);
578
579                         if (unlikely(error)) {
580                                 if (atomic) {
581                                         atomic = 0;
582                                         goto redo2;
583                                 }
584                                 if (!ret)
585                                         ret = error;
586                                 break;
587                         }
588                         ret += chars;
589
590                         /* Insert it into the buffer array */
591                         buf->page = page;
592                         buf->ops = &anon_pipe_buf_ops;
593                         buf->offset = 0;
594                         buf->len = chars;
595                         pipe->nrbufs = ++bufs;
596                         pipe->tmp_page = NULL;
597
598                         total_len -= chars;
599                         if (!total_len)
600                                 break;
601                 }
602                 if (bufs < pipe->buffers)
603                         continue;
604                 if (filp->f_flags & O_NONBLOCK) {
605                         if (!ret)
606                                 ret = -EAGAIN;
607                         break;
608                 }
609                 if (signal_pending(current)) {
610                         if (!ret)
611                                 ret = -ERESTARTSYS;
612                         break;
613                 }
614                 if (do_wakeup) {
615                         wake_up_interruptible_sync(&pipe->wait);
616                         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
617                         do_wakeup = 0;
618                 }
619                 pipe->waiting_writers++;
620                 pipe_wait(pipe);
621                 pipe->waiting_writers--;
622         }
623 out:
624         mutex_unlock(&inode->i_mutex);
625         if (do_wakeup) {
626                 wake_up_interruptible_sync(&pipe->wait);
627                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
628         }
629         if (ret > 0)
630                 file_update_time(filp);
631         return ret;
632 }
633
634 static ssize_t
635 bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
636 {
637         return -EBADF;
638 }
639
640 static ssize_t
641 bad_pipe_w(struct file *filp, const char __user *buf, size_t count,
642            loff_t *ppos)
643 {
644         return -EBADF;
645 }
646
647 static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
648 {
649         struct inode *inode = filp->f_path.dentry->d_inode;
650         struct pipe_inode_info *pipe;
651         int count, buf, nrbufs;
652
653         switch (cmd) {
654                 case FIONREAD:
655                         mutex_lock(&inode->i_mutex);
656                         pipe = inode->i_pipe;
657                         count = 0;
658                         buf = pipe->curbuf;
659                         nrbufs = pipe->nrbufs;
660                         while (--nrbufs >= 0) {
661                                 count += pipe->bufs[buf].len;
662                                 buf = (buf+1) & (pipe->buffers - 1);
663                         }
664                         mutex_unlock(&inode->i_mutex);
665
666                         return put_user(count, (int __user *)arg);
667                 default:
668                         return -EINVAL;
669         }
670 }
671
672 /* No kernel lock held - fine */
673 static unsigned int
674 pipe_poll(struct file *filp, poll_table *wait)
675 {
676         unsigned int mask;
677         struct inode *inode = filp->f_path.dentry->d_inode;
678         struct pipe_inode_info *pipe = inode->i_pipe;
679         int nrbufs;
680
681         poll_wait(filp, &pipe->wait, wait);
682
683         /* Reading only -- no need for acquiring the semaphore.  */
684         nrbufs = pipe->nrbufs;
685         mask = 0;
686         if (filp->f_mode & FMODE_READ) {
687                 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
688                 if (!pipe->writers && filp->f_version != pipe->w_counter)
689                         mask |= POLLHUP;
690         }
691
692         if (filp->f_mode & FMODE_WRITE) {
693                 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
694                 /*
695                  * Most Unices do not set POLLERR for FIFOs but on Linux they
696                  * behave exactly like pipes for poll().
697                  */
698                 if (!pipe->readers)
699                         mask |= POLLERR;
700         }
701
702         return mask;
703 }
704
705 static int
706 pipe_release(struct inode *inode, int decr, int decw)
707 {
708         struct pipe_inode_info *pipe;
709
710         mutex_lock(&inode->i_mutex);
711         pipe = inode->i_pipe;
712         pipe->readers -= decr;
713         pipe->writers -= decw;
714
715         if (!pipe->readers && !pipe->writers) {
716                 free_pipe_info(inode);
717         } else {
718                 wake_up_interruptible_sync(&pipe->wait);
719                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
720                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
721         }
722         mutex_unlock(&inode->i_mutex);
723
724         return 0;
725 }
726
727 static int
728 pipe_read_fasync(int fd, struct file *filp, int on)
729 {
730         struct inode *inode = filp->f_path.dentry->d_inode;
731         int retval;
732
733         mutex_lock(&inode->i_mutex);
734         retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
735         mutex_unlock(&inode->i_mutex);
736
737         return retval;
738 }
739
740
741 static int
742 pipe_write_fasync(int fd, struct file *filp, int on)
743 {
744         struct inode *inode = filp->f_path.dentry->d_inode;
745         int retval;
746
747         mutex_lock(&inode->i_mutex);
748         retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
749         mutex_unlock(&inode->i_mutex);
750
751         return retval;
752 }
753
754
755 static int
756 pipe_rdwr_fasync(int fd, struct file *filp, int on)
757 {
758         struct inode *inode = filp->f_path.dentry->d_inode;
759         struct pipe_inode_info *pipe = inode->i_pipe;
760         int retval;
761
762         mutex_lock(&inode->i_mutex);
763         retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
764         if (retval >= 0) {
765                 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
766                 if (retval < 0) /* this can happen only if on == T */
767                         fasync_helper(-1, filp, 0, &pipe->fasync_readers);
768         }
769         mutex_unlock(&inode->i_mutex);
770         return retval;
771 }
772
773
774 static int
775 pipe_read_release(struct inode *inode, struct file *filp)
776 {
777         return pipe_release(inode, 1, 0);
778 }
779
780 static int
781 pipe_write_release(struct inode *inode, struct file *filp)
782 {
783         return pipe_release(inode, 0, 1);
784 }
785
786 static int
787 pipe_rdwr_release(struct inode *inode, struct file *filp)
788 {
789         int decr, decw;
790
791         decr = (filp->f_mode & FMODE_READ) != 0;
792         decw = (filp->f_mode & FMODE_WRITE) != 0;
793         return pipe_release(inode, decr, decw);
794 }
795
796 static int
797 pipe_read_open(struct inode *inode, struct file *filp)
798 {
799         int ret = -ENOENT;
800
801         mutex_lock(&inode->i_mutex);
802
803         if (inode->i_pipe) {
804                 ret = 0;
805                 inode->i_pipe->readers++;
806         }
807
808         mutex_unlock(&inode->i_mutex);
809
810         return ret;
811 }
812
813 static int
814 pipe_write_open(struct inode *inode, struct file *filp)
815 {
816         int ret = -ENOENT;
817
818         mutex_lock(&inode->i_mutex);
819
820         if (inode->i_pipe) {
821                 ret = 0;
822                 inode->i_pipe->writers++;
823         }
824
825         mutex_unlock(&inode->i_mutex);
826
827         return ret;
828 }
829
830 static int
831 pipe_rdwr_open(struct inode *inode, struct file *filp)
832 {
833         int ret = -ENOENT;
834
835         mutex_lock(&inode->i_mutex);
836
837         if (inode->i_pipe) {
838                 ret = 0;
839                 if (filp->f_mode & FMODE_READ)
840                         inode->i_pipe->readers++;
841                 if (filp->f_mode & FMODE_WRITE)
842                         inode->i_pipe->writers++;
843         }
844
845         mutex_unlock(&inode->i_mutex);
846
847         return ret;
848 }
849
850 /*
851  * The file_operations structs are not static because they
852  * are also used in linux/fs/fifo.c to do operations on FIFOs.
853  *
854  * Pipes reuse fifos' file_operations structs.
855  */
856 const struct file_operations read_pipefifo_fops = {
857         .llseek         = no_llseek,
858         .read           = do_sync_read,
859         .aio_read       = pipe_read,
860         .write          = bad_pipe_w,
861         .poll           = pipe_poll,
862         .unlocked_ioctl = pipe_ioctl,
863         .open           = pipe_read_open,
864         .release        = pipe_read_release,
865         .fasync         = pipe_read_fasync,
866 };
867
868 const struct file_operations write_pipefifo_fops = {
869         .llseek         = no_llseek,
870         .read           = bad_pipe_r,
871         .write          = do_sync_write,
872         .aio_write      = pipe_write,
873         .poll           = pipe_poll,
874         .unlocked_ioctl = pipe_ioctl,
875         .open           = pipe_write_open,
876         .release        = pipe_write_release,
877         .fasync         = pipe_write_fasync,
878 };
879
880 const struct file_operations rdwr_pipefifo_fops = {
881         .llseek         = no_llseek,
882         .read           = do_sync_read,
883         .aio_read       = pipe_read,
884         .write          = do_sync_write,
885         .aio_write      = pipe_write,
886         .poll           = pipe_poll,
887         .unlocked_ioctl = pipe_ioctl,
888         .open           = pipe_rdwr_open,
889         .release        = pipe_rdwr_release,
890         .fasync         = pipe_rdwr_fasync,
891 };
892
893 struct pipe_inode_info * alloc_pipe_info(struct inode *inode)
894 {
895         struct pipe_inode_info *pipe;
896
897         pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
898         if (pipe) {
899                 pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
900                 if (pipe->bufs) {
901                         init_waitqueue_head(&pipe->wait);
902                         pipe->r_counter = pipe->w_counter = 1;
903                         pipe->inode = inode;
904                         pipe->buffers = PIPE_DEF_BUFFERS;
905                         return pipe;
906                 }
907                 kfree(pipe);
908         }
909
910         return NULL;
911 }
912
913 void __free_pipe_info(struct pipe_inode_info *pipe)
914 {
915         int i;
916
917         for (i = 0; i < pipe->buffers; i++) {
918                 struct pipe_buffer *buf = pipe->bufs + i;
919                 if (buf->ops)
920                         buf->ops->release(pipe, buf);
921         }
922         if (pipe->tmp_page)
923                 __free_page(pipe->tmp_page);
924         kfree(pipe->bufs);
925         kfree(pipe);
926 }
927
928 void free_pipe_info(struct inode *inode)
929 {
930         __free_pipe_info(inode->i_pipe);
931         inode->i_pipe = NULL;
932 }
933
934 static struct vfsmount *pipe_mnt __read_mostly;
935
936 /*
937  * pipefs_dname() is called from d_path().
938  */
939 static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
940 {
941         return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
942                                 dentry->d_inode->i_ino);
943 }
944
945 static const struct dentry_operations pipefs_dentry_operations = {
946         .d_dname        = pipefs_dname,
947 };
948
949 static struct inode * get_pipe_inode(void)
950 {
951         struct inode *inode = new_inode(pipe_mnt->mnt_sb);
952         struct pipe_inode_info *pipe;
953
954         if (!inode)
955                 goto fail_inode;
956
957         pipe = alloc_pipe_info(inode);
958         if (!pipe)
959                 goto fail_iput;
960         inode->i_pipe = pipe;
961
962         pipe->readers = pipe->writers = 1;
963         inode->i_fop = &rdwr_pipefifo_fops;
964
965         /*
966          * Mark the inode dirty from the very beginning,
967          * that way it will never be moved to the dirty
968          * list because "mark_inode_dirty()" will think
969          * that it already _is_ on the dirty list.
970          */
971         inode->i_state = I_DIRTY;
972         inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
973         inode->i_uid = current_fsuid();
974         inode->i_gid = current_fsgid();
975         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
976
977         return inode;
978
979 fail_iput:
980         iput(inode);
981
982 fail_inode:
983         return NULL;
984 }
985
986 struct file *create_write_pipe(int flags)
987 {
988         int err;
989         struct inode *inode;
990         struct file *f;
991         struct path path;
992         struct qstr name = { .name = "" };
993
994         err = -ENFILE;
995         inode = get_pipe_inode();
996         if (!inode)
997                 goto err;
998
999         err = -ENOMEM;
1000         path.dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &name);
1001         if (!path.dentry)
1002                 goto err_inode;
1003         path.mnt = mntget(pipe_mnt);
1004
1005         path.dentry->d_op = &pipefs_dentry_operations;
1006         d_instantiate(path.dentry, inode);
1007
1008         err = -ENFILE;
1009         f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops);
1010         if (!f)
1011                 goto err_dentry;
1012         f->f_mapping = inode->i_mapping;
1013
1014         f->f_flags = O_WRONLY | (flags & O_NONBLOCK);
1015         f->f_version = 0;
1016
1017         return f;
1018
1019  err_dentry:
1020         free_pipe_info(inode);
1021         path_put(&path);
1022         return ERR_PTR(err);
1023
1024  err_inode:
1025         free_pipe_info(inode);
1026         iput(inode);
1027  err:
1028         return ERR_PTR(err);
1029 }
1030
1031 void free_write_pipe(struct file *f)
1032 {
1033         free_pipe_info(f->f_dentry->d_inode);
1034         path_put(&f->f_path);
1035         put_filp(f);
1036 }
1037
1038 struct file *create_read_pipe(struct file *wrf, int flags)
1039 {
1040         /* Grab pipe from the writer */
1041         struct file *f = alloc_file(&wrf->f_path, FMODE_READ,
1042                                     &read_pipefifo_fops);
1043         if (!f)
1044                 return ERR_PTR(-ENFILE);
1045
1046         path_get(&wrf->f_path);
1047         f->f_flags = O_RDONLY | (flags & O_NONBLOCK);
1048
1049         return f;
1050 }
1051
1052 int do_pipe_flags(int *fd, int flags)
1053 {
1054         struct file *fw, *fr;
1055         int error;
1056         int fdw, fdr;
1057
1058         if (flags & ~(O_CLOEXEC | O_NONBLOCK))
1059                 return -EINVAL;
1060
1061         fw = create_write_pipe(flags);
1062         if (IS_ERR(fw))
1063                 return PTR_ERR(fw);
1064         fr = create_read_pipe(fw, flags);
1065         error = PTR_ERR(fr);
1066         if (IS_ERR(fr))
1067                 goto err_write_pipe;
1068
1069         error = get_unused_fd_flags(flags);
1070         if (error < 0)
1071                 goto err_read_pipe;
1072         fdr = error;
1073
1074         error = get_unused_fd_flags(flags);
1075         if (error < 0)
1076                 goto err_fdr;
1077         fdw = error;
1078
1079         audit_fd_pair(fdr, fdw);
1080         fd_install(fdr, fr);
1081         fd_install(fdw, fw);
1082         fd[0] = fdr;
1083         fd[1] = fdw;
1084
1085         return 0;
1086
1087  err_fdr:
1088         put_unused_fd(fdr);
1089  err_read_pipe:
1090         path_put(&fr->f_path);
1091         put_filp(fr);
1092  err_write_pipe:
1093         free_write_pipe(fw);
1094         return error;
1095 }
1096
1097 /*
1098  * sys_pipe() is the normal C calling standard for creating
1099  * a pipe. It's not the way Unix traditionally does this, though.
1100  */
1101 SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
1102 {
1103         int fd[2];
1104         int error;
1105
1106         error = do_pipe_flags(fd, flags);
1107         if (!error) {
1108                 if (copy_to_user(fildes, fd, sizeof(fd))) {
1109                         sys_close(fd[0]);
1110                         sys_close(fd[1]);
1111                         error = -EFAULT;
1112                 }
1113         }
1114         return error;
1115 }
1116
1117 SYSCALL_DEFINE1(pipe, int __user *, fildes)
1118 {
1119         return sys_pipe2(fildes, 0);
1120 }
1121
1122 /*
1123  * Allocate a new array of pipe buffers and copy the info over. Returns the
1124  * pipe size if successful, or return -ERROR on error.
1125  */
1126 static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
1127 {
1128         struct pipe_buffer *bufs;
1129
1130         /*
1131          * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1132          * expect a lot of shrink+grow operations, just free and allocate
1133          * again like we would do for growing. If the pipe currently
1134          * contains more buffers than arg, then return busy.
1135          */
1136         if (nr_pages < pipe->nrbufs)
1137                 return -EBUSY;
1138
1139         bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL);
1140         if (unlikely(!bufs))
1141                 return -ENOMEM;
1142
1143         /*
1144          * The pipe array wraps around, so just start the new one at zero
1145          * and adjust the indexes.
1146          */
1147         if (pipe->nrbufs) {
1148                 unsigned int tail;
1149                 unsigned int head;
1150
1151                 tail = pipe->curbuf + pipe->nrbufs;
1152                 if (tail < pipe->buffers)
1153                         tail = 0;
1154                 else
1155                         tail &= (pipe->buffers - 1);
1156
1157                 head = pipe->nrbufs - tail;
1158                 if (head)
1159                         memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1160                 if (tail)
1161                         memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1162         }
1163
1164         pipe->curbuf = 0;
1165         kfree(pipe->bufs);
1166         pipe->bufs = bufs;
1167         pipe->buffers = nr_pages;
1168         return nr_pages * PAGE_SIZE;
1169 }
1170
1171 /*
1172  * Currently we rely on the pipe array holding a power-of-2 number
1173  * of pages.
1174  */
1175 static inline unsigned int round_pipe_size(unsigned int size)
1176 {
1177         unsigned long nr_pages;
1178
1179         nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1180         return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
1181 }
1182
1183 /*
1184  * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax
1185  * will return an error.
1186  */
1187 int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
1188                  size_t *lenp, loff_t *ppos)
1189 {
1190         int ret;
1191
1192         ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
1193         if (ret < 0 || !write)
1194                 return ret;
1195
1196         pipe_max_size = round_pipe_size(pipe_max_size);
1197         return ret;
1198 }
1199
1200 long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1201 {
1202         struct pipe_inode_info *pipe;
1203         long ret;
1204
1205         pipe = file->f_path.dentry->d_inode->i_pipe;
1206         if (!pipe)
1207                 return -EBADF;
1208
1209         mutex_lock(&pipe->inode->i_mutex);
1210
1211         switch (cmd) {
1212         case F_SETPIPE_SZ: {
1213                 unsigned int size, nr_pages;
1214
1215                 size = round_pipe_size(arg);
1216                 nr_pages = size >> PAGE_SHIFT;
1217
1218                 ret = -EINVAL;
1219                 if (!nr_pages)
1220                         goto out;
1221
1222                 if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
1223                         ret = -EPERM;
1224                         goto out;
1225                 }
1226                 ret = pipe_set_size(pipe, nr_pages);
1227                 break;
1228                 }
1229         case F_GETPIPE_SZ:
1230                 ret = pipe->buffers * PAGE_SIZE;
1231                 break;
1232         default:
1233                 ret = -EINVAL;
1234                 break;
1235         }
1236
1237 out:
1238         mutex_unlock(&pipe->inode->i_mutex);
1239         return ret;
1240 }
1241
1242 /*
1243  * pipefs should _never_ be mounted by userland - too much of security hassle,
1244  * no real gain from having the whole whorehouse mounted. So we don't need
1245  * any operations on the root directory. However, we need a non-trivial
1246  * d_name - pipe: will go nicely and kill the special-casing in procfs.
1247  */
1248 static int pipefs_get_sb(struct file_system_type *fs_type,
1249                          int flags, const char *dev_name, void *data,
1250                          struct vfsmount *mnt)
1251 {
1252         return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC, mnt);
1253 }
1254
1255 static struct file_system_type pipe_fs_type = {
1256         .name           = "pipefs",
1257         .get_sb         = pipefs_get_sb,
1258         .kill_sb        = kill_anon_super,
1259 };
1260
1261 static int __init init_pipe_fs(void)
1262 {
1263         int err = register_filesystem(&pipe_fs_type);
1264
1265         if (!err) {
1266                 pipe_mnt = kern_mount(&pipe_fs_type);
1267                 if (IS_ERR(pipe_mnt)) {
1268                         err = PTR_ERR(pipe_mnt);
1269                         unregister_filesystem(&pipe_fs_type);
1270                 }
1271         }
1272         return err;
1273 }
1274
1275 static void __exit exit_pipe_fs(void)
1276 {
1277         unregister_filesystem(&pipe_fs_type);
1278         mntput(pipe_mnt);
1279 }
1280
1281 fs_initcall(init_pipe_fs);
1282 module_exit(exit_pipe_fs);