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