Revert "input: touch: raydium: V61.7 code drop"
[linux-3.10.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/magic.h>
17 #include <linux/pipe_fs_i.h>
18 #include <linux/uio.h>
19 #include <linux/highmem.h>
20 #include <linux/pagemap.h>
21 #include <linux/audit.h>
22 #include <linux/syscalls.h>
23 #include <linux/fcntl.h>
24 #include <linux/aio.h>
25
26 #include <asm/uaccess.h>
27 #include <asm/ioctls.h>
28
29 #include "internal.h"
30
31 /*
32  * The max size that a non-root user is allowed to grow the pipe. Can
33  * be set by root in /proc/sys/fs/pipe-max-size
34  */
35 unsigned int pipe_max_size = 1048576;
36
37 /*
38  * Minimum pipe size, as required by POSIX
39  */
40 unsigned int pipe_min_size = PAGE_SIZE;
41
42 /*
43  * We use a start+len construction, which provides full use of the 
44  * allocated memory.
45  * -- Florian Coosmann (FGC)
46  * 
47  * Reads with count = 0 should always return 0.
48  * -- Julian Bradfield 1999-06-07.
49  *
50  * FIFOs and Pipes now generate SIGIO for both readers and writers.
51  * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
52  *
53  * pipe_read & write cleanup
54  * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
55  */
56
57 static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass)
58 {
59         if (pipe->files)
60                 mutex_lock_nested(&pipe->mutex, subclass);
61 }
62
63 void pipe_lock(struct pipe_inode_info *pipe)
64 {
65         /*
66          * pipe_lock() nests non-pipe inode locks (for writing to a file)
67          */
68         pipe_lock_nested(pipe, I_MUTEX_PARENT);
69 }
70 EXPORT_SYMBOL(pipe_lock);
71
72 void pipe_unlock(struct pipe_inode_info *pipe)
73 {
74         if (pipe->files)
75                 mutex_unlock(&pipe->mutex);
76 }
77 EXPORT_SYMBOL(pipe_unlock);
78
79 static inline void __pipe_lock(struct pipe_inode_info *pipe)
80 {
81         mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT);
82 }
83
84 static inline void __pipe_unlock(struct pipe_inode_info *pipe)
85 {
86         mutex_unlock(&pipe->mutex);
87 }
88
89 void pipe_double_lock(struct pipe_inode_info *pipe1,
90                       struct pipe_inode_info *pipe2)
91 {
92         BUG_ON(pipe1 == pipe2);
93
94         if (pipe1 < pipe2) {
95                 pipe_lock_nested(pipe1, I_MUTEX_PARENT);
96                 pipe_lock_nested(pipe2, I_MUTEX_CHILD);
97         } else {
98                 pipe_lock_nested(pipe2, I_MUTEX_PARENT);
99                 pipe_lock_nested(pipe1, I_MUTEX_CHILD);
100         }
101 }
102
103 /* Drop the inode semaphore and wait for a pipe event, atomically */
104 void pipe_wait(struct pipe_inode_info *pipe)
105 {
106         DEFINE_WAIT(wait);
107
108         /*
109          * Pipes are system-local resources, so sleeping on them
110          * is considered a noninteractive wait:
111          */
112         prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE);
113         pipe_unlock(pipe);
114         schedule();
115         finish_wait(&pipe->wait, &wait);
116         pipe_lock(pipe);
117 }
118
119 static int
120 pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
121                         int atomic)
122 {
123         unsigned long copy;
124
125         while (len > 0) {
126                 while (!iov->iov_len)
127                         iov++;
128                 copy = min_t(unsigned long, len, iov->iov_len);
129
130                 if (atomic) {
131                         if (__copy_from_user_inatomic(to, iov->iov_base, copy))
132                                 return -EFAULT;
133                 } else {
134                         if (copy_from_user(to, iov->iov_base, copy))
135                                 return -EFAULT;
136                 }
137                 to += copy;
138                 len -= copy;
139                 iov->iov_base += copy;
140                 iov->iov_len -= copy;
141         }
142         return 0;
143 }
144
145 static int
146 pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len,
147                       int atomic)
148 {
149         unsigned long copy;
150
151         while (len > 0) {
152                 while (!iov->iov_len)
153                         iov++;
154                 copy = min_t(unsigned long, len, iov->iov_len);
155
156                 if (atomic) {
157                         if (__copy_to_user_inatomic(iov->iov_base, from, copy))
158                                 return -EFAULT;
159                 } else {
160                         if (copy_to_user(iov->iov_base, from, copy))
161                                 return -EFAULT;
162                 }
163                 from += copy;
164                 len -= copy;
165                 iov->iov_base += copy;
166                 iov->iov_len -= copy;
167         }
168         return 0;
169 }
170
171 /*
172  * Attempt to pre-fault in the user memory, so we can use atomic copies.
173  * Returns the number of bytes not faulted in.
174  */
175 static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len)
176 {
177         while (!iov->iov_len)
178                 iov++;
179
180         while (len > 0) {
181                 unsigned long this_len;
182
183                 this_len = min_t(unsigned long, len, iov->iov_len);
184                 if (fault_in_pages_writeable(iov->iov_base, this_len))
185                         break;
186
187                 len -= this_len;
188                 iov++;
189         }
190
191         return len;
192 }
193
194 /*
195  * Pre-fault in the user memory, so we can use atomic copies.
196  */
197 static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
198 {
199         while (!iov->iov_len)
200                 iov++;
201
202         while (len > 0) {
203                 unsigned long this_len;
204
205                 this_len = min_t(unsigned long, len, iov->iov_len);
206                 fault_in_pages_readable(iov->iov_base, this_len);
207                 len -= this_len;
208                 iov++;
209         }
210 }
211
212 static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
213                                   struct pipe_buffer *buf)
214 {
215         struct page *page = buf->page;
216
217         /*
218          * If nobody else uses this page, and we don't already have a
219          * temporary page, let's keep track of it as a one-deep
220          * allocation cache. (Otherwise just release our reference to it)
221          */
222         if (page_count(page) == 1 && !pipe->tmp_page)
223                 pipe->tmp_page = page;
224         else
225                 page_cache_release(page);
226 }
227
228 /**
229  * generic_pipe_buf_map - virtually map a pipe buffer
230  * @pipe:       the pipe that the buffer belongs to
231  * @buf:        the buffer that should be mapped
232  * @atomic:     whether to use an atomic map
233  *
234  * Description:
235  *      This function returns a kernel virtual address mapping for the
236  *      pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided
237  *      and the caller has to be careful not to fault before calling
238  *      the unmap function.
239  *
240  *      Note that this function calls kmap_atomic() if @atomic != 0.
241  */
242 void *generic_pipe_buf_map(struct pipe_inode_info *pipe,
243                            struct pipe_buffer *buf, int atomic)
244 {
245         if (atomic) {
246                 buf->flags |= PIPE_BUF_FLAG_ATOMIC;
247                 return kmap_atomic(buf->page);
248         }
249
250         return kmap(buf->page);
251 }
252 EXPORT_SYMBOL(generic_pipe_buf_map);
253
254 /**
255  * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer
256  * @pipe:       the pipe that the buffer belongs to
257  * @buf:        the buffer that should be unmapped
258  * @map_data:   the data that the mapping function returned
259  *
260  * Description:
261  *      This function undoes the mapping that ->map() provided.
262  */
263 void generic_pipe_buf_unmap(struct pipe_inode_info *pipe,
264                             struct pipe_buffer *buf, void *map_data)
265 {
266         if (buf->flags & PIPE_BUF_FLAG_ATOMIC) {
267                 buf->flags &= ~PIPE_BUF_FLAG_ATOMIC;
268                 kunmap_atomic(map_data);
269         } else
270                 kunmap(buf->page);
271 }
272 EXPORT_SYMBOL(generic_pipe_buf_unmap);
273
274 /**
275  * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
276  * @pipe:       the pipe that the buffer belongs to
277  * @buf:        the buffer to attempt to steal
278  *
279  * Description:
280  *      This function attempts to steal the &struct page attached to
281  *      @buf. If successful, this function returns 0 and returns with
282  *      the page locked. The caller may then reuse the page for whatever
283  *      he wishes; the typical use is insertion into a different file
284  *      page cache.
285  */
286 int generic_pipe_buf_steal(struct pipe_inode_info *pipe,
287                            struct pipe_buffer *buf)
288 {
289         struct page *page = buf->page;
290
291         /*
292          * A reference of one is golden, that means that the owner of this
293          * page is the only one holding a reference to it. lock the page
294          * and return OK.
295          */
296         if (page_count(page) == 1) {
297                 lock_page(page);
298                 return 0;
299         }
300
301         return 1;
302 }
303 EXPORT_SYMBOL(generic_pipe_buf_steal);
304
305 /**
306  * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
307  * @pipe:       the pipe that the buffer belongs to
308  * @buf:        the buffer to get a reference to
309  *
310  * Description:
311  *      This function grabs an extra reference to @buf. It's used in
312  *      in the tee() system call, when we duplicate the buffers in one
313  *      pipe into another.
314  */
315 void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
316 {
317         page_cache_get(buf->page);
318 }
319 EXPORT_SYMBOL(generic_pipe_buf_get);
320
321 /**
322  * generic_pipe_buf_confirm - verify contents of the pipe buffer
323  * @info:       the pipe that the buffer belongs to
324  * @buf:        the buffer to confirm
325  *
326  * Description:
327  *      This function does nothing, because the generic pipe code uses
328  *      pages that are always good when inserted into the pipe.
329  */
330 int generic_pipe_buf_confirm(struct pipe_inode_info *info,
331                              struct pipe_buffer *buf)
332 {
333         return 0;
334 }
335 EXPORT_SYMBOL(generic_pipe_buf_confirm);
336
337 /**
338  * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
339  * @pipe:       the pipe that the buffer belongs to
340  * @buf:        the buffer to put a reference to
341  *
342  * Description:
343  *      This function releases a reference to @buf.
344  */
345 void generic_pipe_buf_release(struct pipe_inode_info *pipe,
346                               struct pipe_buffer *buf)
347 {
348         page_cache_release(buf->page);
349 }
350 EXPORT_SYMBOL(generic_pipe_buf_release);
351
352 static const struct pipe_buf_operations anon_pipe_buf_ops = {
353         .can_merge = 1,
354         .map = generic_pipe_buf_map,
355         .unmap = generic_pipe_buf_unmap,
356         .confirm = generic_pipe_buf_confirm,
357         .release = anon_pipe_buf_release,
358         .steal = generic_pipe_buf_steal,
359         .get = generic_pipe_buf_get,
360 };
361
362 static const struct pipe_buf_operations packet_pipe_buf_ops = {
363         .can_merge = 0,
364         .map = generic_pipe_buf_map,
365         .unmap = generic_pipe_buf_unmap,
366         .confirm = generic_pipe_buf_confirm,
367         .release = anon_pipe_buf_release,
368         .steal = generic_pipe_buf_steal,
369         .get = generic_pipe_buf_get,
370 };
371
372 static ssize_t
373 pipe_read(struct kiocb *iocb, const struct iovec *_iov,
374            unsigned long nr_segs, loff_t pos)
375 {
376         struct file *filp = iocb->ki_filp;
377         struct pipe_inode_info *pipe = filp->private_data;
378         int do_wakeup;
379         ssize_t ret;
380         struct iovec *iov = (struct iovec *)_iov;
381         size_t total_len;
382
383         total_len = iov_length(iov, nr_segs);
384         /* Null read succeeds. */
385         if (unlikely(total_len == 0))
386                 return 0;
387
388         do_wakeup = 0;
389         ret = 0;
390         __pipe_lock(pipe);
391         for (;;) {
392                 int bufs = pipe->nrbufs;
393                 if (bufs) {
394                         int curbuf = pipe->curbuf;
395                         struct pipe_buffer *buf = pipe->bufs + curbuf;
396                         const struct pipe_buf_operations *ops = buf->ops;
397                         void *addr;
398                         size_t chars = buf->len;
399                         int error, atomic;
400
401                         if (chars > total_len)
402                                 chars = total_len;
403
404                         error = ops->confirm(pipe, buf);
405                         if (error) {
406                                 if (!ret)
407                                         ret = error;
408                                 break;
409                         }
410
411                         atomic = !iov_fault_in_pages_write(iov, chars);
412 redo:
413                         addr = ops->map(pipe, buf, atomic);
414                         error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
415                         ops->unmap(pipe, buf, addr);
416                         if (unlikely(error)) {
417                                 /*
418                                  * Just retry with the slow path if we failed.
419                                  */
420                                 if (atomic) {
421                                         atomic = 0;
422                                         goto redo;
423                                 }
424                                 if (!ret)
425                                         ret = error;
426                                 break;
427                         }
428                         ret += chars;
429                         buf->offset += chars;
430                         buf->len -= chars;
431
432                         /* Was it a packet buffer? Clean up and exit */
433                         if (buf->flags & PIPE_BUF_FLAG_PACKET) {
434                                 total_len = chars;
435                                 buf->len = 0;
436                         }
437
438                         if (!buf->len) {
439                                 buf->ops = NULL;
440                                 ops->release(pipe, buf);
441                                 curbuf = (curbuf + 1) & (pipe->buffers - 1);
442                                 pipe->curbuf = curbuf;
443                                 pipe->nrbufs = --bufs;
444                                 do_wakeup = 1;
445                         }
446                         total_len -= chars;
447                         if (!total_len)
448                                 break;  /* common path: read succeeded */
449                 }
450                 if (bufs)       /* More to do? */
451                         continue;
452                 if (!pipe->writers)
453                         break;
454                 if (!pipe->waiting_writers) {
455                         /* syscall merging: Usually we must not sleep
456                          * if O_NONBLOCK is set, or if we got some data.
457                          * But if a writer sleeps in kernel space, then
458                          * we can wait for that data without violating POSIX.
459                          */
460                         if (ret)
461                                 break;
462                         if (filp->f_flags & O_NONBLOCK) {
463                                 ret = -EAGAIN;
464                                 break;
465                         }
466                 }
467                 if (signal_pending(current)) {
468                         if (!ret)
469                                 ret = -ERESTARTSYS;
470                         break;
471                 }
472                 if (do_wakeup) {
473                         wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
474                         kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
475                 }
476                 pipe_wait(pipe);
477         }
478         __pipe_unlock(pipe);
479
480         /* Signal writers asynchronously that there is more room. */
481         if (do_wakeup) {
482                 wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM);
483                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
484         }
485         if (ret > 0)
486                 file_accessed(filp);
487         return ret;
488 }
489
490 static inline int is_packetized(struct file *file)
491 {
492         return (file->f_flags & O_DIRECT) != 0;
493 }
494
495 static ssize_t
496 pipe_write(struct kiocb *iocb, const struct iovec *_iov,
497             unsigned long nr_segs, loff_t ppos)
498 {
499         struct file *filp = iocb->ki_filp;
500         struct pipe_inode_info *pipe = filp->private_data;
501         ssize_t ret;
502         int do_wakeup;
503         struct iovec *iov = (struct iovec *)_iov;
504         size_t total_len;
505         ssize_t chars;
506
507         total_len = iov_length(iov, nr_segs);
508         /* Null write succeeds. */
509         if (unlikely(total_len == 0))
510                 return 0;
511
512         do_wakeup = 0;
513         ret = 0;
514         __pipe_lock(pipe);
515
516         if (!pipe->readers) {
517                 send_sig(SIGPIPE, current, 0);
518                 ret = -EPIPE;
519                 goto out;
520         }
521
522         /* We try to merge small writes */
523         chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
524         if (pipe->nrbufs && chars != 0) {
525                 int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) &
526                                                         (pipe->buffers - 1);
527                 struct pipe_buffer *buf = pipe->bufs + lastbuf;
528                 const struct pipe_buf_operations *ops = buf->ops;
529                 int offset = buf->offset + buf->len;
530
531                 if (ops->can_merge && offset + chars <= PAGE_SIZE) {
532                         int error, atomic = 1;
533                         void *addr;
534
535                         error = ops->confirm(pipe, buf);
536                         if (error)
537                                 goto out;
538
539                         iov_fault_in_pages_read(iov, chars);
540 redo1:
541                         addr = ops->map(pipe, buf, atomic);
542                         error = pipe_iov_copy_from_user(offset + addr, iov,
543                                                         chars, atomic);
544                         ops->unmap(pipe, buf, addr);
545                         ret = error;
546                         do_wakeup = 1;
547                         if (error) {
548                                 if (atomic) {
549                                         atomic = 0;
550                                         goto redo1;
551                                 }
552                                 goto out;
553                         }
554                         buf->len += chars;
555                         total_len -= chars;
556                         ret = chars;
557                         if (!total_len)
558                                 goto out;
559                 }
560         }
561
562         for (;;) {
563                 int bufs;
564
565                 if (!pipe->readers) {
566                         send_sig(SIGPIPE, current, 0);
567                         if (!ret)
568                                 ret = -EPIPE;
569                         break;
570                 }
571                 bufs = pipe->nrbufs;
572                 if (bufs < pipe->buffers) {
573                         int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
574                         struct pipe_buffer *buf = pipe->bufs + newbuf;
575                         struct page *page = pipe->tmp_page;
576                         char *src;
577                         int error, atomic = 1;
578
579                         if (!page) {
580                                 page = alloc_page(GFP_HIGHUSER);
581                                 if (unlikely(!page)) {
582                                         ret = ret ? : -ENOMEM;
583                                         break;
584                                 }
585                                 pipe->tmp_page = page;
586                         }
587                         /* Always wake up, even if the copy fails. Otherwise
588                          * we lock up (O_NONBLOCK-)readers that sleep due to
589                          * syscall merging.
590                          * FIXME! Is this really true?
591                          */
592                         do_wakeup = 1;
593                         chars = PAGE_SIZE;
594                         if (chars > total_len)
595                                 chars = total_len;
596
597                         iov_fault_in_pages_read(iov, chars);
598 redo2:
599                         if (atomic)
600                                 src = kmap_atomic(page);
601                         else
602                                 src = kmap(page);
603
604                         error = pipe_iov_copy_from_user(src, iov, chars,
605                                                         atomic);
606                         if (atomic)
607                                 kunmap_atomic(src);
608                         else
609                                 kunmap(page);
610
611                         if (unlikely(error)) {
612                                 if (atomic) {
613                                         atomic = 0;
614                                         goto redo2;
615                                 }
616                                 if (!ret)
617                                         ret = error;
618                                 break;
619                         }
620                         ret += chars;
621
622                         /* Insert it into the buffer array */
623                         buf->page = page;
624                         buf->ops = &anon_pipe_buf_ops;
625                         buf->offset = 0;
626                         buf->len = chars;
627                         buf->flags = 0;
628                         if (is_packetized(filp)) {
629                                 buf->ops = &packet_pipe_buf_ops;
630                                 buf->flags = PIPE_BUF_FLAG_PACKET;
631                         }
632                         pipe->nrbufs = ++bufs;
633                         pipe->tmp_page = NULL;
634
635                         total_len -= chars;
636                         if (!total_len)
637                                 break;
638                 }
639                 if (bufs < pipe->buffers)
640                         continue;
641                 if (filp->f_flags & O_NONBLOCK) {
642                         if (!ret)
643                                 ret = -EAGAIN;
644                         break;
645                 }
646                 if (signal_pending(current)) {
647                         if (!ret)
648                                 ret = -ERESTARTSYS;
649                         break;
650                 }
651                 if (do_wakeup) {
652                         wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
653                         kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
654                         do_wakeup = 0;
655                 }
656                 pipe->waiting_writers++;
657                 pipe_wait(pipe);
658                 pipe->waiting_writers--;
659         }
660 out:
661         __pipe_unlock(pipe);
662         if (do_wakeup) {
663                 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM);
664                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
665         }
666         if (ret > 0) {
667                 int err = file_update_time(filp);
668                 if (err)
669                         ret = err;
670         }
671         return ret;
672 }
673
674 static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
675 {
676         struct pipe_inode_info *pipe = filp->private_data;
677         int count, buf, nrbufs;
678
679         switch (cmd) {
680                 case FIONREAD:
681                         __pipe_lock(pipe);
682                         count = 0;
683                         buf = pipe->curbuf;
684                         nrbufs = pipe->nrbufs;
685                         while (--nrbufs >= 0) {
686                                 count += pipe->bufs[buf].len;
687                                 buf = (buf+1) & (pipe->buffers - 1);
688                         }
689                         __pipe_unlock(pipe);
690
691                         return put_user(count, (int __user *)arg);
692                 default:
693                         return -ENOIOCTLCMD;
694         }
695 }
696
697 /* No kernel lock held - fine */
698 static unsigned int
699 pipe_poll(struct file *filp, poll_table *wait)
700 {
701         unsigned int mask;
702         struct pipe_inode_info *pipe = filp->private_data;
703         int nrbufs;
704
705         poll_wait(filp, &pipe->wait, wait);
706
707         /* Reading only -- no need for acquiring the semaphore.  */
708         nrbufs = pipe->nrbufs;
709         mask = 0;
710         if (filp->f_mode & FMODE_READ) {
711                 mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
712                 if (!pipe->writers && filp->f_version != pipe->w_counter)
713                         mask |= POLLHUP;
714         }
715
716         if (filp->f_mode & FMODE_WRITE) {
717                 mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0;
718                 /*
719                  * Most Unices do not set POLLERR for FIFOs but on Linux they
720                  * behave exactly like pipes for poll().
721                  */
722                 if (!pipe->readers)
723                         mask |= POLLERR;
724         }
725
726         return mask;
727 }
728
729 static void put_pipe_info(struct inode *inode, struct pipe_inode_info *pipe)
730 {
731         int kill = 0;
732
733         spin_lock(&inode->i_lock);
734         if (!--pipe->files) {
735                 inode->i_pipe = NULL;
736                 kill = 1;
737         }
738         spin_unlock(&inode->i_lock);
739
740         if (kill)
741                 free_pipe_info(pipe);
742 }
743
744 static int
745 pipe_release(struct inode *inode, struct file *file)
746 {
747         struct pipe_inode_info *pipe = file->private_data;
748
749         __pipe_lock(pipe);
750         if (file->f_mode & FMODE_READ)
751                 pipe->readers--;
752         if (file->f_mode & FMODE_WRITE)
753                 pipe->writers--;
754
755         if (pipe->readers || pipe->writers) {
756                 wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP);
757                 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
758                 kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
759         }
760         __pipe_unlock(pipe);
761
762         put_pipe_info(inode, pipe);
763         return 0;
764 }
765
766 static int
767 pipe_fasync(int fd, struct file *filp, int on)
768 {
769         struct pipe_inode_info *pipe = filp->private_data;
770         int retval = 0;
771
772         __pipe_lock(pipe);
773         if (filp->f_mode & FMODE_READ)
774                 retval = fasync_helper(fd, filp, on, &pipe->fasync_readers);
775         if ((filp->f_mode & FMODE_WRITE) && retval >= 0) {
776                 retval = fasync_helper(fd, filp, on, &pipe->fasync_writers);
777                 if (retval < 0 && (filp->f_mode & FMODE_READ))
778                         /* this can happen only if on == T */
779                         fasync_helper(-1, filp, 0, &pipe->fasync_readers);
780         }
781         __pipe_unlock(pipe);
782         return retval;
783 }
784
785 struct pipe_inode_info *alloc_pipe_info(void)
786 {
787         struct pipe_inode_info *pipe;
788
789         pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
790         if (pipe) {
791                 pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
792                 if (pipe->bufs) {
793                         init_waitqueue_head(&pipe->wait);
794                         pipe->r_counter = pipe->w_counter = 1;
795                         pipe->buffers = PIPE_DEF_BUFFERS;
796                         mutex_init(&pipe->mutex);
797                         return pipe;
798                 }
799                 kfree(pipe);
800         }
801
802         return NULL;
803 }
804
805 void free_pipe_info(struct pipe_inode_info *pipe)
806 {
807         int i;
808
809         for (i = 0; i < pipe->buffers; i++) {
810                 struct pipe_buffer *buf = pipe->bufs + i;
811                 if (buf->ops)
812                         buf->ops->release(pipe, buf);
813         }
814         if (pipe->tmp_page)
815                 __free_page(pipe->tmp_page);
816         kfree(pipe->bufs);
817         kfree(pipe);
818 }
819
820 static struct vfsmount *pipe_mnt __read_mostly;
821
822 /*
823  * pipefs_dname() is called from d_path().
824  */
825 static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen)
826 {
827         return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]",
828                                 dentry->d_inode->i_ino);
829 }
830
831 static const struct dentry_operations pipefs_dentry_operations = {
832         .d_dname        = pipefs_dname,
833 };
834
835 static struct inode * get_pipe_inode(void)
836 {
837         struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb);
838         struct pipe_inode_info *pipe;
839
840         if (!inode)
841                 goto fail_inode;
842
843         inode->i_ino = get_next_ino();
844
845         pipe = alloc_pipe_info();
846         if (!pipe)
847                 goto fail_iput;
848
849         inode->i_pipe = pipe;
850         pipe->files = 2;
851         pipe->readers = pipe->writers = 1;
852         inode->i_fop = &pipefifo_fops;
853
854         /*
855          * Mark the inode dirty from the very beginning,
856          * that way it will never be moved to the dirty
857          * list because "mark_inode_dirty()" will think
858          * that it already _is_ on the dirty list.
859          */
860         inode->i_state = I_DIRTY;
861         inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
862         inode->i_uid = current_fsuid();
863         inode->i_gid = current_fsgid();
864         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
865
866         return inode;
867
868 fail_iput:
869         iput(inode);
870
871 fail_inode:
872         return NULL;
873 }
874
875 int create_pipe_files(struct file **res, int flags)
876 {
877         int err;
878         struct inode *inode = get_pipe_inode();
879         struct file *f;
880         struct path path;
881         static struct qstr name = { .name = "" };
882
883         if (!inode)
884                 return -ENFILE;
885
886         err = -ENOMEM;
887         path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name);
888         if (!path.dentry)
889                 goto err_inode;
890         path.mnt = mntget(pipe_mnt);
891
892         d_instantiate(path.dentry, inode);
893
894         err = -ENFILE;
895         f = alloc_file(&path, FMODE_WRITE, &pipefifo_fops);
896         if (IS_ERR(f))
897                 goto err_dentry;
898
899         f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT));
900         f->private_data = inode->i_pipe;
901
902         res[0] = alloc_file(&path, FMODE_READ, &pipefifo_fops);
903         if (IS_ERR(res[0]))
904                 goto err_file;
905
906         path_get(&path);
907         res[0]->private_data = inode->i_pipe;
908         res[0]->f_flags = O_RDONLY | (flags & O_NONBLOCK);
909         res[1] = f;
910         return 0;
911
912 err_file:
913         put_filp(f);
914 err_dentry:
915         free_pipe_info(inode->i_pipe);
916         path_put(&path);
917         return err;
918
919 err_inode:
920         free_pipe_info(inode->i_pipe);
921         iput(inode);
922         return err;
923 }
924
925 static int __do_pipe_flags(int *fd, struct file **files, int flags)
926 {
927         int error;
928         int fdw, fdr;
929
930         if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT))
931                 return -EINVAL;
932
933         error = create_pipe_files(files, flags);
934         if (error)
935                 return error;
936
937         error = get_unused_fd_flags(flags);
938         if (error < 0)
939                 goto err_read_pipe;
940         fdr = error;
941
942         error = get_unused_fd_flags(flags);
943         if (error < 0)
944                 goto err_fdr;
945         fdw = error;
946
947         audit_fd_pair(fdr, fdw);
948         fd[0] = fdr;
949         fd[1] = fdw;
950         return 0;
951
952  err_fdr:
953         put_unused_fd(fdr);
954  err_read_pipe:
955         fput(files[0]);
956         fput(files[1]);
957         return error;
958 }
959
960 int do_pipe_flags(int *fd, int flags)
961 {
962         struct file *files[2];
963         int error = __do_pipe_flags(fd, files, flags);
964         if (!error) {
965                 fd_install(fd[0], files[0]);
966                 fd_install(fd[1], files[1]);
967         }
968         return error;
969 }
970
971 /*
972  * sys_pipe() is the normal C calling standard for creating
973  * a pipe. It's not the way Unix traditionally does this, though.
974  */
975 SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags)
976 {
977         struct file *files[2];
978         int fd[2];
979         int error;
980
981         error = __do_pipe_flags(fd, files, flags);
982         if (!error) {
983                 if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) {
984                         fput(files[0]);
985                         fput(files[1]);
986                         put_unused_fd(fd[0]);
987                         put_unused_fd(fd[1]);
988                         error = -EFAULT;
989                 } else {
990                         fd_install(fd[0], files[0]);
991                         fd_install(fd[1], files[1]);
992                 }
993         }
994         return error;
995 }
996
997 SYSCALL_DEFINE1(pipe, int __user *, fildes)
998 {
999         return sys_pipe2(fildes, 0);
1000 }
1001
1002 static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt)
1003 {
1004         int cur = *cnt; 
1005
1006         while (cur == *cnt) {
1007                 pipe_wait(pipe);
1008                 if (signal_pending(current))
1009                         break;
1010         }
1011         return cur == *cnt ? -ERESTARTSYS : 0;
1012 }
1013
1014 static void wake_up_partner(struct pipe_inode_info *pipe)
1015 {
1016         wake_up_interruptible(&pipe->wait);
1017 }
1018
1019 static int fifo_open(struct inode *inode, struct file *filp)
1020 {
1021         struct pipe_inode_info *pipe;
1022         bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC;
1023         int ret;
1024
1025         filp->f_version = 0;
1026
1027         spin_lock(&inode->i_lock);
1028         if (inode->i_pipe) {
1029                 pipe = inode->i_pipe;
1030                 pipe->files++;
1031                 spin_unlock(&inode->i_lock);
1032         } else {
1033                 spin_unlock(&inode->i_lock);
1034                 pipe = alloc_pipe_info();
1035                 if (!pipe)
1036                         return -ENOMEM;
1037                 pipe->files = 1;
1038                 spin_lock(&inode->i_lock);
1039                 if (unlikely(inode->i_pipe)) {
1040                         inode->i_pipe->files++;
1041                         spin_unlock(&inode->i_lock);
1042                         free_pipe_info(pipe);
1043                         pipe = inode->i_pipe;
1044                 } else {
1045                         inode->i_pipe = pipe;
1046                         spin_unlock(&inode->i_lock);
1047                 }
1048         }
1049         filp->private_data = pipe;
1050         /* OK, we have a pipe and it's pinned down */
1051
1052         __pipe_lock(pipe);
1053
1054         /* We can only do regular read/write on fifos */
1055         filp->f_mode &= (FMODE_READ | FMODE_WRITE);
1056
1057         switch (filp->f_mode) {
1058         case FMODE_READ:
1059         /*
1060          *  O_RDONLY
1061          *  POSIX.1 says that O_NONBLOCK means return with the FIFO
1062          *  opened, even when there is no process writing the FIFO.
1063          */
1064                 pipe->r_counter++;
1065                 if (pipe->readers++ == 0)
1066                         wake_up_partner(pipe);
1067
1068                 if (!is_pipe && !pipe->writers) {
1069                         if ((filp->f_flags & O_NONBLOCK)) {
1070                                 /* suppress POLLHUP until we have
1071                                  * seen a writer */
1072                                 filp->f_version = pipe->w_counter;
1073                         } else {
1074                                 if (wait_for_partner(pipe, &pipe->w_counter))
1075                                         goto err_rd;
1076                         }
1077                 }
1078                 break;
1079         
1080         case FMODE_WRITE:
1081         /*
1082          *  O_WRONLY
1083          *  POSIX.1 says that O_NONBLOCK means return -1 with
1084          *  errno=ENXIO when there is no process reading the FIFO.
1085          */
1086                 ret = -ENXIO;
1087                 if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers)
1088                         goto err;
1089
1090                 pipe->w_counter++;
1091                 if (!pipe->writers++)
1092                         wake_up_partner(pipe);
1093
1094                 if (!is_pipe && !pipe->readers) {
1095                         if (wait_for_partner(pipe, &pipe->r_counter))
1096                                 goto err_wr;
1097                 }
1098                 break;
1099         
1100         case FMODE_READ | FMODE_WRITE:
1101         /*
1102          *  O_RDWR
1103          *  POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
1104          *  This implementation will NEVER block on a O_RDWR open, since
1105          *  the process can at least talk to itself.
1106          */
1107
1108                 pipe->readers++;
1109                 pipe->writers++;
1110                 pipe->r_counter++;
1111                 pipe->w_counter++;
1112                 if (pipe->readers == 1 || pipe->writers == 1)
1113                         wake_up_partner(pipe);
1114                 break;
1115
1116         default:
1117                 ret = -EINVAL;
1118                 goto err;
1119         }
1120
1121         /* Ok! */
1122         __pipe_unlock(pipe);
1123         return 0;
1124
1125 err_rd:
1126         if (!--pipe->readers)
1127                 wake_up_interruptible(&pipe->wait);
1128         ret = -ERESTARTSYS;
1129         goto err;
1130
1131 err_wr:
1132         if (!--pipe->writers)
1133                 wake_up_interruptible(&pipe->wait);
1134         ret = -ERESTARTSYS;
1135         goto err;
1136
1137 err:
1138         __pipe_unlock(pipe);
1139
1140         put_pipe_info(inode, pipe);
1141         return ret;
1142 }
1143
1144 const struct file_operations pipefifo_fops = {
1145         .open           = fifo_open,
1146         .llseek         = no_llseek,
1147         .read           = do_sync_read,
1148         .aio_read       = pipe_read,
1149         .write          = do_sync_write,
1150         .aio_write      = pipe_write,
1151         .poll           = pipe_poll,
1152         .unlocked_ioctl = pipe_ioctl,
1153         .release        = pipe_release,
1154         .fasync         = pipe_fasync,
1155 };
1156
1157 /*
1158  * Allocate a new array of pipe buffers and copy the info over. Returns the
1159  * pipe size if successful, or return -ERROR on error.
1160  */
1161 static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
1162 {
1163         struct pipe_buffer *bufs;
1164
1165         /*
1166          * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1167          * expect a lot of shrink+grow operations, just free and allocate
1168          * again like we would do for growing. If the pipe currently
1169          * contains more buffers than arg, then return busy.
1170          */
1171         if (nr_pages < pipe->nrbufs)
1172                 return -EBUSY;
1173
1174         bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL | __GFP_NOWARN);
1175         if (unlikely(!bufs))
1176                 return -ENOMEM;
1177
1178         /*
1179          * The pipe array wraps around, so just start the new one at zero
1180          * and adjust the indexes.
1181          */
1182         if (pipe->nrbufs) {
1183                 unsigned int tail;
1184                 unsigned int head;
1185
1186                 tail = pipe->curbuf + pipe->nrbufs;
1187                 if (tail < pipe->buffers)
1188                         tail = 0;
1189                 else
1190                         tail &= (pipe->buffers - 1);
1191
1192                 head = pipe->nrbufs - tail;
1193                 if (head)
1194                         memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
1195                 if (tail)
1196                         memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
1197         }
1198
1199         pipe->curbuf = 0;
1200         kfree(pipe->bufs);
1201         pipe->bufs = bufs;
1202         pipe->buffers = nr_pages;
1203         return nr_pages * PAGE_SIZE;
1204 }
1205
1206 /*
1207  * Currently we rely on the pipe array holding a power-of-2 number
1208  * of pages.
1209  */
1210 static inline unsigned int round_pipe_size(unsigned int size)
1211 {
1212         unsigned long nr_pages;
1213
1214         nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
1215         return roundup_pow_of_two(nr_pages) << PAGE_SHIFT;
1216 }
1217
1218 /*
1219  * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax
1220  * will return an error.
1221  */
1222 int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
1223                  size_t *lenp, loff_t *ppos)
1224 {
1225         int ret;
1226
1227         ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
1228         if (ret < 0 || !write)
1229                 return ret;
1230
1231         pipe_max_size = round_pipe_size(pipe_max_size);
1232         return ret;
1233 }
1234
1235 /*
1236  * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same
1237  * location, so checking ->i_pipe is not enough to verify that this is a
1238  * pipe.
1239  */
1240 struct pipe_inode_info *get_pipe_info(struct file *file)
1241 {
1242         return file->f_op == &pipefifo_fops ? file->private_data : NULL;
1243 }
1244
1245 long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
1246 {
1247         struct pipe_inode_info *pipe;
1248         long ret;
1249
1250         pipe = get_pipe_info(file);
1251         if (!pipe)
1252                 return -EBADF;
1253
1254         __pipe_lock(pipe);
1255
1256         switch (cmd) {
1257         case F_SETPIPE_SZ: {
1258                 unsigned int size, nr_pages;
1259
1260                 size = round_pipe_size(arg);
1261                 nr_pages = size >> PAGE_SHIFT;
1262
1263                 ret = -EINVAL;
1264                 if (!nr_pages)
1265                         goto out;
1266
1267                 if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
1268                         ret = -EPERM;
1269                         goto out;
1270                 }
1271                 ret = pipe_set_size(pipe, nr_pages);
1272                 break;
1273                 }
1274         case F_GETPIPE_SZ:
1275                 ret = pipe->buffers * PAGE_SIZE;
1276                 break;
1277         default:
1278                 ret = -EINVAL;
1279                 break;
1280         }
1281
1282 out:
1283         __pipe_unlock(pipe);
1284         return ret;
1285 }
1286
1287 static const struct super_operations pipefs_ops = {
1288         .destroy_inode = free_inode_nonrcu,
1289         .statfs = simple_statfs,
1290 };
1291
1292 /*
1293  * pipefs should _never_ be mounted by userland - too much of security hassle,
1294  * no real gain from having the whole whorehouse mounted. So we don't need
1295  * any operations on the root directory. However, we need a non-trivial
1296  * d_name - pipe: will go nicely and kill the special-casing in procfs.
1297  */
1298 static struct dentry *pipefs_mount(struct file_system_type *fs_type,
1299                          int flags, const char *dev_name, void *data)
1300 {
1301         return mount_pseudo(fs_type, "pipe:", &pipefs_ops,
1302                         &pipefs_dentry_operations, PIPEFS_MAGIC);
1303 }
1304
1305 static struct file_system_type pipe_fs_type = {
1306         .name           = "pipefs",
1307         .mount          = pipefs_mount,
1308         .kill_sb        = kill_anon_super,
1309 };
1310
1311 static int __init init_pipe_fs(void)
1312 {
1313         int err = register_filesystem(&pipe_fs_type);
1314
1315         if (!err) {
1316                 pipe_mnt = kern_mount(&pipe_fs_type);
1317                 if (IS_ERR(pipe_mnt)) {
1318                         err = PTR_ERR(pipe_mnt);
1319                         unregister_filesystem(&pipe_fs_type);
1320                 }
1321         }
1322         return err;
1323 }
1324
1325 fs_initcall(init_pipe_fs);