4 * Copyright (C) 1991, 1992, 1999 Linus Torvalds
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>
14 #include <linux/log2.h>
15 #include <linux/mount.h>
16 #include <linux/pipe_fs_i.h>
17 #include <linux/uio.h>
18 #include <linux/highmem.h>
19 #include <linux/pagemap.h>
20 #include <linux/audit.h>
21 #include <linux/syscalls.h>
22 #include <linux/fcntl.h>
24 #include <asm/uaccess.h>
25 #include <asm/ioctls.h>
28 * The max size that a non-root user is allowed to grow the pipe. Can
29 * be set by root in /proc/sys/fs/pipe-max-pages
31 unsigned int pipe_max_pages
= PIPE_DEF_BUFFERS
* 16;
34 * We use a start+len construction, which provides full use of the
36 * -- Florian Coosmann (FGC)
38 * Reads with count = 0 should always return 0.
39 * -- Julian Bradfield 1999-06-07.
41 * FIFOs and Pipes now generate SIGIO for both readers and writers.
42 * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
44 * pipe_read & write cleanup
45 * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
48 static void pipe_lock_nested(struct pipe_inode_info
*pipe
, int subclass
)
51 mutex_lock_nested(&pipe
->inode
->i_mutex
, subclass
);
54 void pipe_lock(struct pipe_inode_info
*pipe
)
57 * pipe_lock() nests non-pipe inode locks (for writing to a file)
59 pipe_lock_nested(pipe
, I_MUTEX_PARENT
);
61 EXPORT_SYMBOL(pipe_lock
);
63 void pipe_unlock(struct pipe_inode_info
*pipe
)
66 mutex_unlock(&pipe
->inode
->i_mutex
);
68 EXPORT_SYMBOL(pipe_unlock
);
70 void pipe_double_lock(struct pipe_inode_info
*pipe1
,
71 struct pipe_inode_info
*pipe2
)
73 BUG_ON(pipe1
== pipe2
);
76 pipe_lock_nested(pipe1
, I_MUTEX_PARENT
);
77 pipe_lock_nested(pipe2
, I_MUTEX_CHILD
);
79 pipe_lock_nested(pipe2
, I_MUTEX_PARENT
);
80 pipe_lock_nested(pipe1
, I_MUTEX_CHILD
);
84 /* Drop the inode semaphore and wait for a pipe event, atomically */
85 void pipe_wait(struct pipe_inode_info
*pipe
)
90 * Pipes are system-local resources, so sleeping on them
91 * is considered a noninteractive wait:
93 prepare_to_wait(&pipe
->wait
, &wait
, TASK_INTERRUPTIBLE
);
96 finish_wait(&pipe
->wait
, &wait
);
101 pipe_iov_copy_from_user(void *to
, struct iovec
*iov
, unsigned long len
,
107 while (!iov
->iov_len
)
109 copy
= min_t(unsigned long, len
, iov
->iov_len
);
112 if (__copy_from_user_inatomic(to
, iov
->iov_base
, copy
))
115 if (copy_from_user(to
, iov
->iov_base
, copy
))
120 iov
->iov_base
+= copy
;
121 iov
->iov_len
-= copy
;
127 pipe_iov_copy_to_user(struct iovec
*iov
, const void *from
, unsigned long len
,
133 while (!iov
->iov_len
)
135 copy
= min_t(unsigned long, len
, iov
->iov_len
);
138 if (__copy_to_user_inatomic(iov
->iov_base
, from
, copy
))
141 if (copy_to_user(iov
->iov_base
, from
, copy
))
146 iov
->iov_base
+= copy
;
147 iov
->iov_len
-= copy
;
153 * Attempt to pre-fault in the user memory, so we can use atomic copies.
154 * Returns the number of bytes not faulted in.
156 static int iov_fault_in_pages_write(struct iovec
*iov
, unsigned long len
)
158 while (!iov
->iov_len
)
162 unsigned long this_len
;
164 this_len
= min_t(unsigned long, len
, iov
->iov_len
);
165 if (fault_in_pages_writeable(iov
->iov_base
, this_len
))
176 * Pre-fault in the user memory, so we can use atomic copies.
178 static void iov_fault_in_pages_read(struct iovec
*iov
, unsigned long len
)
180 while (!iov
->iov_len
)
184 unsigned long this_len
;
186 this_len
= min_t(unsigned long, len
, iov
->iov_len
);
187 fault_in_pages_readable(iov
->iov_base
, this_len
);
193 static void anon_pipe_buf_release(struct pipe_inode_info
*pipe
,
194 struct pipe_buffer
*buf
)
196 struct page
*page
= buf
->page
;
199 * If nobody else uses this page, and we don't already have a
200 * temporary page, let's keep track of it as a one-deep
201 * allocation cache. (Otherwise just release our reference to it)
203 if (page_count(page
) == 1 && !pipe
->tmp_page
)
204 pipe
->tmp_page
= page
;
206 page_cache_release(page
);
210 * generic_pipe_buf_map - virtually map a pipe buffer
211 * @pipe: the pipe that the buffer belongs to
212 * @buf: the buffer that should be mapped
213 * @atomic: whether to use an atomic map
216 * This function returns a kernel virtual address mapping for the
217 * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided
218 * and the caller has to be careful not to fault before calling
219 * the unmap function.
221 * Note that this function occupies KM_USER0 if @atomic != 0.
223 void *generic_pipe_buf_map(struct pipe_inode_info
*pipe
,
224 struct pipe_buffer
*buf
, int atomic
)
227 buf
->flags
|= PIPE_BUF_FLAG_ATOMIC
;
228 return kmap_atomic(buf
->page
, KM_USER0
);
231 return kmap(buf
->page
);
235 * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer
236 * @pipe: the pipe that the buffer belongs to
237 * @buf: the buffer that should be unmapped
238 * @map_data: the data that the mapping function returned
241 * This function undoes the mapping that ->map() provided.
243 void generic_pipe_buf_unmap(struct pipe_inode_info
*pipe
,
244 struct pipe_buffer
*buf
, void *map_data
)
246 if (buf
->flags
& PIPE_BUF_FLAG_ATOMIC
) {
247 buf
->flags
&= ~PIPE_BUF_FLAG_ATOMIC
;
248 kunmap_atomic(map_data
, KM_USER0
);
254 * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer
255 * @pipe: the pipe that the buffer belongs to
256 * @buf: the buffer to attempt to steal
259 * This function attempts to steal the &struct page attached to
260 * @buf. If successful, this function returns 0 and returns with
261 * the page locked. The caller may then reuse the page for whatever
262 * he wishes; the typical use is insertion into a different file
265 int generic_pipe_buf_steal(struct pipe_inode_info
*pipe
,
266 struct pipe_buffer
*buf
)
268 struct page
*page
= buf
->page
;
271 * A reference of one is golden, that means that the owner of this
272 * page is the only one holding a reference to it. lock the page
275 if (page_count(page
) == 1) {
284 * generic_pipe_buf_get - get a reference to a &struct pipe_buffer
285 * @pipe: the pipe that the buffer belongs to
286 * @buf: the buffer to get a reference to
289 * This function grabs an extra reference to @buf. It's used in
290 * in the tee() system call, when we duplicate the buffers in one
293 void generic_pipe_buf_get(struct pipe_inode_info
*pipe
, struct pipe_buffer
*buf
)
295 page_cache_get(buf
->page
);
299 * generic_pipe_buf_confirm - verify contents of the pipe buffer
300 * @info: the pipe that the buffer belongs to
301 * @buf: the buffer to confirm
304 * This function does nothing, because the generic pipe code uses
305 * pages that are always good when inserted into the pipe.
307 int generic_pipe_buf_confirm(struct pipe_inode_info
*info
,
308 struct pipe_buffer
*buf
)
314 * generic_pipe_buf_release - put a reference to a &struct pipe_buffer
315 * @pipe: the pipe that the buffer belongs to
316 * @buf: the buffer to put a reference to
319 * This function releases a reference to @buf.
321 void generic_pipe_buf_release(struct pipe_inode_info
*pipe
,
322 struct pipe_buffer
*buf
)
324 page_cache_release(buf
->page
);
327 static const struct pipe_buf_operations anon_pipe_buf_ops
= {
329 .map
= generic_pipe_buf_map
,
330 .unmap
= generic_pipe_buf_unmap
,
331 .confirm
= generic_pipe_buf_confirm
,
332 .release
= anon_pipe_buf_release
,
333 .steal
= generic_pipe_buf_steal
,
334 .get
= generic_pipe_buf_get
,
338 pipe_read(struct kiocb
*iocb
, const struct iovec
*_iov
,
339 unsigned long nr_segs
, loff_t pos
)
341 struct file
*filp
= iocb
->ki_filp
;
342 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
343 struct pipe_inode_info
*pipe
;
346 struct iovec
*iov
= (struct iovec
*)_iov
;
349 total_len
= iov_length(iov
, nr_segs
);
350 /* Null read succeeds. */
351 if (unlikely(total_len
== 0))
356 mutex_lock(&inode
->i_mutex
);
357 pipe
= inode
->i_pipe
;
359 int bufs
= pipe
->nrbufs
;
361 int curbuf
= pipe
->curbuf
;
362 struct pipe_buffer
*buf
= pipe
->bufs
+ curbuf
;
363 const struct pipe_buf_operations
*ops
= buf
->ops
;
365 size_t chars
= buf
->len
;
368 if (chars
> total_len
)
371 error
= ops
->confirm(pipe
, buf
);
378 atomic
= !iov_fault_in_pages_write(iov
, chars
);
380 addr
= ops
->map(pipe
, buf
, atomic
);
381 error
= pipe_iov_copy_to_user(iov
, addr
+ buf
->offset
, chars
, atomic
);
382 ops
->unmap(pipe
, buf
, addr
);
383 if (unlikely(error
)) {
385 * Just retry with the slow path if we failed.
396 buf
->offset
+= chars
;
400 ops
->release(pipe
, buf
);
401 curbuf
= (curbuf
+ 1) & (pipe
->buffers
- 1);
402 pipe
->curbuf
= curbuf
;
403 pipe
->nrbufs
= --bufs
;
408 break; /* common path: read succeeded */
410 if (bufs
) /* More to do? */
414 if (!pipe
->waiting_writers
) {
415 /* syscall merging: Usually we must not sleep
416 * if O_NONBLOCK is set, or if we got some data.
417 * But if a writer sleeps in kernel space, then
418 * we can wait for that data without violating POSIX.
422 if (filp
->f_flags
& O_NONBLOCK
) {
427 if (signal_pending(current
)) {
433 wake_up_interruptible_sync(&pipe
->wait
);
434 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
438 mutex_unlock(&inode
->i_mutex
);
440 /* Signal writers asynchronously that there is more room. */
442 wake_up_interruptible_sync(&pipe
->wait
);
443 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
451 pipe_write(struct kiocb
*iocb
, const struct iovec
*_iov
,
452 unsigned long nr_segs
, loff_t ppos
)
454 struct file
*filp
= iocb
->ki_filp
;
455 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
456 struct pipe_inode_info
*pipe
;
459 struct iovec
*iov
= (struct iovec
*)_iov
;
463 total_len
= iov_length(iov
, nr_segs
);
464 /* Null write succeeds. */
465 if (unlikely(total_len
== 0))
470 mutex_lock(&inode
->i_mutex
);
471 pipe
= inode
->i_pipe
;
473 if (!pipe
->readers
) {
474 send_sig(SIGPIPE
, current
, 0);
479 /* We try to merge small writes */
480 chars
= total_len
& (PAGE_SIZE
-1); /* size of the last buffer */
481 if (pipe
->nrbufs
&& chars
!= 0) {
482 int lastbuf
= (pipe
->curbuf
+ pipe
->nrbufs
- 1) &
484 struct pipe_buffer
*buf
= pipe
->bufs
+ lastbuf
;
485 const struct pipe_buf_operations
*ops
= buf
->ops
;
486 int offset
= buf
->offset
+ buf
->len
;
488 if (ops
->can_merge
&& offset
+ chars
<= PAGE_SIZE
) {
489 int error
, atomic
= 1;
492 error
= ops
->confirm(pipe
, buf
);
496 iov_fault_in_pages_read(iov
, chars
);
498 addr
= ops
->map(pipe
, buf
, atomic
);
499 error
= pipe_iov_copy_from_user(offset
+ addr
, iov
,
501 ops
->unmap(pipe
, buf
, addr
);
522 if (!pipe
->readers
) {
523 send_sig(SIGPIPE
, current
, 0);
529 if (bufs
< pipe
->buffers
) {
530 int newbuf
= (pipe
->curbuf
+ bufs
) & (pipe
->buffers
-1);
531 struct pipe_buffer
*buf
= pipe
->bufs
+ newbuf
;
532 struct page
*page
= pipe
->tmp_page
;
534 int error
, atomic
= 1;
537 page
= alloc_page(GFP_HIGHUSER
);
538 if (unlikely(!page
)) {
539 ret
= ret
? : -ENOMEM
;
542 pipe
->tmp_page
= page
;
544 /* Always wake up, even if the copy fails. Otherwise
545 * we lock up (O_NONBLOCK-)readers that sleep due to
547 * FIXME! Is this really true?
551 if (chars
> total_len
)
554 iov_fault_in_pages_read(iov
, chars
);
557 src
= kmap_atomic(page
, KM_USER0
);
561 error
= pipe_iov_copy_from_user(src
, iov
, chars
,
564 kunmap_atomic(src
, KM_USER0
);
568 if (unlikely(error
)) {
579 /* Insert it into the buffer array */
581 buf
->ops
= &anon_pipe_buf_ops
;
584 pipe
->nrbufs
= ++bufs
;
585 pipe
->tmp_page
= NULL
;
591 if (bufs
< pipe
->buffers
)
593 if (filp
->f_flags
& O_NONBLOCK
) {
598 if (signal_pending(current
)) {
604 wake_up_interruptible_sync(&pipe
->wait
);
605 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
608 pipe
->waiting_writers
++;
610 pipe
->waiting_writers
--;
613 mutex_unlock(&inode
->i_mutex
);
615 wake_up_interruptible_sync(&pipe
->wait
);
616 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
619 file_update_time(filp
);
624 bad_pipe_r(struct file
*filp
, char __user
*buf
, size_t count
, loff_t
*ppos
)
630 bad_pipe_w(struct file
*filp
, const char __user
*buf
, size_t count
,
636 static long pipe_ioctl(struct file
*filp
, unsigned int cmd
, unsigned long arg
)
638 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
639 struct pipe_inode_info
*pipe
;
640 int count
, buf
, nrbufs
;
644 mutex_lock(&inode
->i_mutex
);
645 pipe
= inode
->i_pipe
;
648 nrbufs
= pipe
->nrbufs
;
649 while (--nrbufs
>= 0) {
650 count
+= pipe
->bufs
[buf
].len
;
651 buf
= (buf
+1) & (pipe
->buffers
- 1);
653 mutex_unlock(&inode
->i_mutex
);
655 return put_user(count
, (int __user
*)arg
);
661 /* No kernel lock held - fine */
663 pipe_poll(struct file
*filp
, poll_table
*wait
)
666 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
667 struct pipe_inode_info
*pipe
= inode
->i_pipe
;
670 poll_wait(filp
, &pipe
->wait
, wait
);
672 /* Reading only -- no need for acquiring the semaphore. */
673 nrbufs
= pipe
->nrbufs
;
675 if (filp
->f_mode
& FMODE_READ
) {
676 mask
= (nrbufs
> 0) ? POLLIN
| POLLRDNORM
: 0;
677 if (!pipe
->writers
&& filp
->f_version
!= pipe
->w_counter
)
681 if (filp
->f_mode
& FMODE_WRITE
) {
682 mask
|= (nrbufs
< pipe
->buffers
) ? POLLOUT
| POLLWRNORM
: 0;
684 * Most Unices do not set POLLERR for FIFOs but on Linux they
685 * behave exactly like pipes for poll().
695 pipe_release(struct inode
*inode
, int decr
, int decw
)
697 struct pipe_inode_info
*pipe
;
699 mutex_lock(&inode
->i_mutex
);
700 pipe
= inode
->i_pipe
;
701 pipe
->readers
-= decr
;
702 pipe
->writers
-= decw
;
704 if (!pipe
->readers
&& !pipe
->writers
) {
705 free_pipe_info(inode
);
707 wake_up_interruptible_sync(&pipe
->wait
);
708 kill_fasync(&pipe
->fasync_readers
, SIGIO
, POLL_IN
);
709 kill_fasync(&pipe
->fasync_writers
, SIGIO
, POLL_OUT
);
711 mutex_unlock(&inode
->i_mutex
);
717 pipe_read_fasync(int fd
, struct file
*filp
, int on
)
719 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
722 mutex_lock(&inode
->i_mutex
);
723 retval
= fasync_helper(fd
, filp
, on
, &inode
->i_pipe
->fasync_readers
);
724 mutex_unlock(&inode
->i_mutex
);
731 pipe_write_fasync(int fd
, struct file
*filp
, int on
)
733 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
736 mutex_lock(&inode
->i_mutex
);
737 retval
= fasync_helper(fd
, filp
, on
, &inode
->i_pipe
->fasync_writers
);
738 mutex_unlock(&inode
->i_mutex
);
745 pipe_rdwr_fasync(int fd
, struct file
*filp
, int on
)
747 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
748 struct pipe_inode_info
*pipe
= inode
->i_pipe
;
751 mutex_lock(&inode
->i_mutex
);
752 retval
= fasync_helper(fd
, filp
, on
, &pipe
->fasync_readers
);
754 retval
= fasync_helper(fd
, filp
, on
, &pipe
->fasync_writers
);
755 if (retval
< 0) /* this can happen only if on == T */
756 fasync_helper(-1, filp
, 0, &pipe
->fasync_readers
);
758 mutex_unlock(&inode
->i_mutex
);
764 pipe_read_release(struct inode
*inode
, struct file
*filp
)
766 return pipe_release(inode
, 1, 0);
770 pipe_write_release(struct inode
*inode
, struct file
*filp
)
772 return pipe_release(inode
, 0, 1);
776 pipe_rdwr_release(struct inode
*inode
, struct file
*filp
)
780 decr
= (filp
->f_mode
& FMODE_READ
) != 0;
781 decw
= (filp
->f_mode
& FMODE_WRITE
) != 0;
782 return pipe_release(inode
, decr
, decw
);
786 pipe_read_open(struct inode
*inode
, struct file
*filp
)
790 mutex_lock(&inode
->i_mutex
);
794 inode
->i_pipe
->readers
++;
797 mutex_unlock(&inode
->i_mutex
);
803 pipe_write_open(struct inode
*inode
, struct file
*filp
)
807 mutex_lock(&inode
->i_mutex
);
811 inode
->i_pipe
->writers
++;
814 mutex_unlock(&inode
->i_mutex
);
820 pipe_rdwr_open(struct inode
*inode
, struct file
*filp
)
824 mutex_lock(&inode
->i_mutex
);
828 if (filp
->f_mode
& FMODE_READ
)
829 inode
->i_pipe
->readers
++;
830 if (filp
->f_mode
& FMODE_WRITE
)
831 inode
->i_pipe
->writers
++;
834 mutex_unlock(&inode
->i_mutex
);
840 * The file_operations structs are not static because they
841 * are also used in linux/fs/fifo.c to do operations on FIFOs.
843 * Pipes reuse fifos' file_operations structs.
845 const struct file_operations read_pipefifo_fops
= {
847 .read
= do_sync_read
,
848 .aio_read
= pipe_read
,
851 .unlocked_ioctl
= pipe_ioctl
,
852 .open
= pipe_read_open
,
853 .release
= pipe_read_release
,
854 .fasync
= pipe_read_fasync
,
857 const struct file_operations write_pipefifo_fops
= {
860 .write
= do_sync_write
,
861 .aio_write
= pipe_write
,
863 .unlocked_ioctl
= pipe_ioctl
,
864 .open
= pipe_write_open
,
865 .release
= pipe_write_release
,
866 .fasync
= pipe_write_fasync
,
869 const struct file_operations rdwr_pipefifo_fops
= {
871 .read
= do_sync_read
,
872 .aio_read
= pipe_read
,
873 .write
= do_sync_write
,
874 .aio_write
= pipe_write
,
876 .unlocked_ioctl
= pipe_ioctl
,
877 .open
= pipe_rdwr_open
,
878 .release
= pipe_rdwr_release
,
879 .fasync
= pipe_rdwr_fasync
,
882 struct pipe_inode_info
* alloc_pipe_info(struct inode
*inode
)
884 struct pipe_inode_info
*pipe
;
886 pipe
= kzalloc(sizeof(struct pipe_inode_info
), GFP_KERNEL
);
888 pipe
->bufs
= kzalloc(sizeof(struct pipe_buffer
) * PIPE_DEF_BUFFERS
, GFP_KERNEL
);
890 init_waitqueue_head(&pipe
->wait
);
891 pipe
->r_counter
= pipe
->w_counter
= 1;
893 pipe
->buffers
= PIPE_DEF_BUFFERS
;
902 void __free_pipe_info(struct pipe_inode_info
*pipe
)
906 for (i
= 0; i
< pipe
->buffers
; i
++) {
907 struct pipe_buffer
*buf
= pipe
->bufs
+ i
;
909 buf
->ops
->release(pipe
, buf
);
912 __free_page(pipe
->tmp_page
);
917 void free_pipe_info(struct inode
*inode
)
919 __free_pipe_info(inode
->i_pipe
);
920 inode
->i_pipe
= NULL
;
923 static struct vfsmount
*pipe_mnt __read_mostly
;
926 * pipefs_dname() is called from d_path().
928 static char *pipefs_dname(struct dentry
*dentry
, char *buffer
, int buflen
)
930 return dynamic_dname(dentry
, buffer
, buflen
, "pipe:[%lu]",
931 dentry
->d_inode
->i_ino
);
934 static const struct dentry_operations pipefs_dentry_operations
= {
935 .d_dname
= pipefs_dname
,
938 static struct inode
* get_pipe_inode(void)
940 struct inode
*inode
= new_inode(pipe_mnt
->mnt_sb
);
941 struct pipe_inode_info
*pipe
;
946 pipe
= alloc_pipe_info(inode
);
949 inode
->i_pipe
= pipe
;
951 pipe
->readers
= pipe
->writers
= 1;
952 inode
->i_fop
= &rdwr_pipefifo_fops
;
955 * Mark the inode dirty from the very beginning,
956 * that way it will never be moved to the dirty
957 * list because "mark_inode_dirty()" will think
958 * that it already _is_ on the dirty list.
960 inode
->i_state
= I_DIRTY
;
961 inode
->i_mode
= S_IFIFO
| S_IRUSR
| S_IWUSR
;
962 inode
->i_uid
= current_fsuid();
963 inode
->i_gid
= current_fsgid();
964 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
975 struct file
*create_write_pipe(int flags
)
981 struct qstr name
= { .name
= "" };
984 inode
= get_pipe_inode();
989 path
.dentry
= d_alloc(pipe_mnt
->mnt_sb
->s_root
, &name
);
992 path
.mnt
= mntget(pipe_mnt
);
994 path
.dentry
->d_op
= &pipefs_dentry_operations
;
995 d_instantiate(path
.dentry
, inode
);
998 f
= alloc_file(&path
, FMODE_WRITE
, &write_pipefifo_fops
);
1001 f
->f_mapping
= inode
->i_mapping
;
1003 f
->f_flags
= O_WRONLY
| (flags
& O_NONBLOCK
);
1009 free_pipe_info(inode
);
1011 return ERR_PTR(err
);
1014 free_pipe_info(inode
);
1017 return ERR_PTR(err
);
1020 void free_write_pipe(struct file
*f
)
1022 free_pipe_info(f
->f_dentry
->d_inode
);
1023 path_put(&f
->f_path
);
1027 struct file
*create_read_pipe(struct file
*wrf
, int flags
)
1029 /* Grab pipe from the writer */
1030 struct file
*f
= alloc_file(&wrf
->f_path
, FMODE_READ
,
1031 &read_pipefifo_fops
);
1033 return ERR_PTR(-ENFILE
);
1035 path_get(&wrf
->f_path
);
1036 f
->f_flags
= O_RDONLY
| (flags
& O_NONBLOCK
);
1041 int do_pipe_flags(int *fd
, int flags
)
1043 struct file
*fw
, *fr
;
1047 if (flags
& ~(O_CLOEXEC
| O_NONBLOCK
))
1050 fw
= create_write_pipe(flags
);
1053 fr
= create_read_pipe(fw
, flags
);
1054 error
= PTR_ERR(fr
);
1056 goto err_write_pipe
;
1058 error
= get_unused_fd_flags(flags
);
1063 error
= get_unused_fd_flags(flags
);
1068 audit_fd_pair(fdr
, fdw
);
1069 fd_install(fdr
, fr
);
1070 fd_install(fdw
, fw
);
1079 path_put(&fr
->f_path
);
1082 free_write_pipe(fw
);
1087 * sys_pipe() is the normal C calling standard for creating
1088 * a pipe. It's not the way Unix traditionally does this, though.
1090 SYSCALL_DEFINE2(pipe2
, int __user
*, fildes
, int, flags
)
1095 error
= do_pipe_flags(fd
, flags
);
1097 if (copy_to_user(fildes
, fd
, sizeof(fd
))) {
1106 SYSCALL_DEFINE1(pipe
, int __user
*, fildes
)
1108 return sys_pipe2(fildes
, 0);
1112 * Allocate a new array of pipe buffers and copy the info over. Returns the
1113 * pipe size if successful, or return -ERROR on error.
1115 static long pipe_set_size(struct pipe_inode_info
*pipe
, unsigned long arg
)
1117 struct pipe_buffer
*bufs
;
1120 * Must be a power-of-2 currently
1122 if (!is_power_of_2(arg
))
1126 * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't
1127 * expect a lot of shrink+grow operations, just free and allocate
1128 * again like we would do for growing. If the pipe currently
1129 * contains more buffers than arg, then return busy.
1131 if (arg
< pipe
->nrbufs
)
1134 bufs
= kcalloc(arg
, sizeof(struct pipe_buffer
), GFP_KERNEL
);
1135 if (unlikely(!bufs
))
1139 * The pipe array wraps around, so just start the new one at zero
1140 * and adjust the indexes.
1143 const unsigned int tail
= pipe
->nrbufs
& (pipe
->buffers
- 1);
1144 const unsigned int head
= pipe
->nrbufs
- tail
;
1147 memcpy(bufs
, pipe
->bufs
+ pipe
->curbuf
, head
* sizeof(struct pipe_buffer
));
1149 memcpy(bufs
+ head
, pipe
->bufs
+ pipe
->curbuf
, tail
* sizeof(struct pipe_buffer
));
1155 pipe
->buffers
= arg
;
1159 long pipe_fcntl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
1161 struct pipe_inode_info
*pipe
;
1164 pipe
= file
->f_path
.dentry
->d_inode
->i_pipe
;
1168 mutex_lock(&pipe
->inode
->i_mutex
);
1172 if (!capable(CAP_SYS_ADMIN
) && arg
> pipe_max_pages
)
1175 * The pipe needs to be at least 2 pages large to
1176 * guarantee POSIX behaviour.
1180 ret
= pipe_set_size(pipe
, arg
);
1183 ret
= pipe
->buffers
;
1190 mutex_unlock(&pipe
->inode
->i_mutex
);
1195 * pipefs should _never_ be mounted by userland - too much of security hassle,
1196 * no real gain from having the whole whorehouse mounted. So we don't need
1197 * any operations on the root directory. However, we need a non-trivial
1198 * d_name - pipe: will go nicely and kill the special-casing in procfs.
1200 static int pipefs_get_sb(struct file_system_type
*fs_type
,
1201 int flags
, const char *dev_name
, void *data
,
1202 struct vfsmount
*mnt
)
1204 return get_sb_pseudo(fs_type
, "pipe:", NULL
, PIPEFS_MAGIC
, mnt
);
1207 static struct file_system_type pipe_fs_type
= {
1209 .get_sb
= pipefs_get_sb
,
1210 .kill_sb
= kill_anon_super
,
1213 static int __init
init_pipe_fs(void)
1215 int err
= register_filesystem(&pipe_fs_type
);
1218 pipe_mnt
= kern_mount(&pipe_fs_type
);
1219 if (IS_ERR(pipe_mnt
)) {
1220 err
= PTR_ERR(pipe_mnt
);
1221 unregister_filesystem(&pipe_fs_type
);
1227 static void __exit
exit_pipe_fs(void)
1229 unregister_filesystem(&pipe_fs_type
);
1233 fs_initcall(init_pipe_fs
);
1234 module_exit(exit_pipe_fs
);