![Jens Axboe](/assets/img/avatar_default.png)
This enables the caller to migrate pages from one address space page cache to another. In buzz word marketing, you can do zero-copy file copies! Signed-off-by: Jens Axboe <axboe@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
871 lines
19 KiB
C
871 lines
19 KiB
C
/*
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* linux/fs/pipe.c
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*
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* Copyright (C) 1991, 1992, 1999 Linus Torvalds
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*/
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#include <linux/mm.h>
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#include <linux/file.h>
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#include <linux/poll.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/pipe_fs_i.h>
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#include <linux/uio.h>
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#include <linux/highmem.h>
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#include <linux/pagemap.h>
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#include <asm/uaccess.h>
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#include <asm/ioctls.h>
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/*
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* We use a start+len construction, which provides full use of the
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* allocated memory.
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* -- Florian Coosmann (FGC)
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*
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* Reads with count = 0 should always return 0.
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* -- Julian Bradfield 1999-06-07.
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*
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* FIFOs and Pipes now generate SIGIO for both readers and writers.
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* -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
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*
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* pipe_read & write cleanup
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* -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
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*/
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/* Drop the inode semaphore and wait for a pipe event, atomically */
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void pipe_wait(struct inode * inode)
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{
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DEFINE_WAIT(wait);
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/*
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* Pipes are system-local resources, so sleeping on them
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* is considered a noninteractive wait:
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*/
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prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE|TASK_NONINTERACTIVE);
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mutex_unlock(PIPE_MUTEX(*inode));
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schedule();
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finish_wait(PIPE_WAIT(*inode), &wait);
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mutex_lock(PIPE_MUTEX(*inode));
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}
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static int
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pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len)
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{
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unsigned long copy;
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while (len > 0) {
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while (!iov->iov_len)
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iov++;
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copy = min_t(unsigned long, len, iov->iov_len);
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if (copy_from_user(to, iov->iov_base, copy))
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return -EFAULT;
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to += copy;
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len -= copy;
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iov->iov_base += copy;
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iov->iov_len -= copy;
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}
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return 0;
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}
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static int
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pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len)
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{
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unsigned long copy;
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while (len > 0) {
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while (!iov->iov_len)
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iov++;
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copy = min_t(unsigned long, len, iov->iov_len);
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if (copy_to_user(iov->iov_base, from, copy))
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return -EFAULT;
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from += copy;
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len -= copy;
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iov->iov_base += copy;
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iov->iov_len -= copy;
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}
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return 0;
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}
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static void anon_pipe_buf_release(struct pipe_inode_info *info, struct pipe_buffer *buf)
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{
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struct page *page = buf->page;
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/*
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* If nobody else uses this page, and we don't already have a
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* temporary page, let's keep track of it as a one-deep
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* allocation cache
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*/
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if (page_count(page) == 1 && !info->tmp_page) {
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info->tmp_page = page;
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return;
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}
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/*
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* Otherwise just release our reference to it
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*/
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page_cache_release(page);
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}
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static void *anon_pipe_buf_map(struct file *file, struct pipe_inode_info *info, struct pipe_buffer *buf)
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{
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return kmap(buf->page);
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}
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static void anon_pipe_buf_unmap(struct pipe_inode_info *info, struct pipe_buffer *buf)
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{
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kunmap(buf->page);
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}
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static int anon_pipe_buf_steal(struct pipe_inode_info *info,
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struct pipe_buffer *buf)
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{
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buf->stolen = 1;
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return 0;
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}
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static struct pipe_buf_operations anon_pipe_buf_ops = {
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.can_merge = 1,
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.map = anon_pipe_buf_map,
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.unmap = anon_pipe_buf_unmap,
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.release = anon_pipe_buf_release,
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.steal = anon_pipe_buf_steal,
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};
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static ssize_t
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pipe_readv(struct file *filp, const struct iovec *_iov,
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unsigned long nr_segs, loff_t *ppos)
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{
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struct inode *inode = filp->f_dentry->d_inode;
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struct pipe_inode_info *info;
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int do_wakeup;
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ssize_t ret;
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struct iovec *iov = (struct iovec *)_iov;
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size_t total_len;
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total_len = iov_length(iov, nr_segs);
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/* Null read succeeds. */
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if (unlikely(total_len == 0))
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return 0;
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do_wakeup = 0;
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ret = 0;
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mutex_lock(PIPE_MUTEX(*inode));
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info = inode->i_pipe;
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for (;;) {
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int bufs = info->nrbufs;
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if (bufs) {
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int curbuf = info->curbuf;
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struct pipe_buffer *buf = info->bufs + curbuf;
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struct pipe_buf_operations *ops = buf->ops;
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void *addr;
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size_t chars = buf->len;
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int error;
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if (chars > total_len)
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chars = total_len;
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addr = ops->map(filp, info, buf);
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if (IS_ERR(addr)) {
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if (!ret)
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ret = PTR_ERR(addr);
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break;
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}
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error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars);
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ops->unmap(info, buf);
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if (unlikely(error)) {
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if (!ret) ret = -EFAULT;
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break;
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}
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ret += chars;
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buf->offset += chars;
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buf->len -= chars;
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if (!buf->len) {
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buf->ops = NULL;
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ops->release(info, buf);
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curbuf = (curbuf + 1) & (PIPE_BUFFERS-1);
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info->curbuf = curbuf;
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info->nrbufs = --bufs;
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do_wakeup = 1;
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}
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total_len -= chars;
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if (!total_len)
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break; /* common path: read succeeded */
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}
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if (bufs) /* More to do? */
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continue;
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if (!PIPE_WRITERS(*inode))
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break;
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if (!PIPE_WAITING_WRITERS(*inode)) {
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/* syscall merging: Usually we must not sleep
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* if O_NONBLOCK is set, or if we got some data.
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* But if a writer sleeps in kernel space, then
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* we can wait for that data without violating POSIX.
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*/
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if (ret)
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break;
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if (filp->f_flags & O_NONBLOCK) {
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ret = -EAGAIN;
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break;
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}
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}
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if (signal_pending(current)) {
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if (!ret) ret = -ERESTARTSYS;
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break;
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}
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if (do_wakeup) {
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wake_up_interruptible_sync(PIPE_WAIT(*inode));
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kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
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}
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pipe_wait(inode);
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}
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mutex_unlock(PIPE_MUTEX(*inode));
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/* Signal writers asynchronously that there is more room. */
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if (do_wakeup) {
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wake_up_interruptible(PIPE_WAIT(*inode));
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kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
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}
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if (ret > 0)
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file_accessed(filp);
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return ret;
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}
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static ssize_t
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pipe_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
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{
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struct iovec iov = { .iov_base = buf, .iov_len = count };
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return pipe_readv(filp, &iov, 1, ppos);
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}
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static ssize_t
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pipe_writev(struct file *filp, const struct iovec *_iov,
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unsigned long nr_segs, loff_t *ppos)
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{
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struct inode *inode = filp->f_dentry->d_inode;
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struct pipe_inode_info *info;
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ssize_t ret;
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int do_wakeup;
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struct iovec *iov = (struct iovec *)_iov;
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size_t total_len;
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ssize_t chars;
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total_len = iov_length(iov, nr_segs);
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/* Null write succeeds. */
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if (unlikely(total_len == 0))
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return 0;
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do_wakeup = 0;
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ret = 0;
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mutex_lock(PIPE_MUTEX(*inode));
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info = inode->i_pipe;
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if (!PIPE_READERS(*inode)) {
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send_sig(SIGPIPE, current, 0);
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ret = -EPIPE;
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goto out;
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}
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/* We try to merge small writes */
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chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
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if (info->nrbufs && chars != 0) {
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int lastbuf = (info->curbuf + info->nrbufs - 1) & (PIPE_BUFFERS-1);
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struct pipe_buffer *buf = info->bufs + lastbuf;
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struct pipe_buf_operations *ops = buf->ops;
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int offset = buf->offset + buf->len;
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if (ops->can_merge && offset + chars <= PAGE_SIZE) {
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void *addr;
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int error;
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addr = ops->map(filp, info, buf);
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if (IS_ERR(addr)) {
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error = PTR_ERR(addr);
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goto out;
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}
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error = pipe_iov_copy_from_user(offset + addr, iov,
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chars);
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ops->unmap(info, buf);
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ret = error;
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do_wakeup = 1;
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if (error)
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goto out;
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buf->len += chars;
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total_len -= chars;
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ret = chars;
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if (!total_len)
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goto out;
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}
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}
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for (;;) {
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int bufs;
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if (!PIPE_READERS(*inode)) {
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send_sig(SIGPIPE, current, 0);
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if (!ret) ret = -EPIPE;
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break;
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}
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bufs = info->nrbufs;
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if (bufs < PIPE_BUFFERS) {
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int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS-1);
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struct pipe_buffer *buf = info->bufs + newbuf;
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struct page *page = info->tmp_page;
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int error;
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if (!page) {
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page = alloc_page(GFP_HIGHUSER);
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if (unlikely(!page)) {
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ret = ret ? : -ENOMEM;
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break;
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}
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info->tmp_page = page;
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}
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/* Always wakeup, even if the copy fails. Otherwise
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* we lock up (O_NONBLOCK-)readers that sleep due to
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* syscall merging.
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* FIXME! Is this really true?
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*/
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do_wakeup = 1;
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chars = PAGE_SIZE;
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if (chars > total_len)
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chars = total_len;
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error = pipe_iov_copy_from_user(kmap(page), iov, chars);
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kunmap(page);
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if (unlikely(error)) {
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if (!ret) ret = -EFAULT;
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break;
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}
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ret += chars;
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/* Insert it into the buffer array */
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buf->page = page;
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buf->ops = &anon_pipe_buf_ops;
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buf->offset = 0;
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buf->len = chars;
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info->nrbufs = ++bufs;
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info->tmp_page = NULL;
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total_len -= chars;
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if (!total_len)
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break;
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}
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if (bufs < PIPE_BUFFERS)
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continue;
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if (filp->f_flags & O_NONBLOCK) {
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if (!ret) ret = -EAGAIN;
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break;
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}
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if (signal_pending(current)) {
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if (!ret) ret = -ERESTARTSYS;
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break;
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}
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if (do_wakeup) {
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wake_up_interruptible_sync(PIPE_WAIT(*inode));
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kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
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do_wakeup = 0;
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}
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PIPE_WAITING_WRITERS(*inode)++;
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pipe_wait(inode);
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PIPE_WAITING_WRITERS(*inode)--;
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}
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out:
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mutex_unlock(PIPE_MUTEX(*inode));
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if (do_wakeup) {
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wake_up_interruptible(PIPE_WAIT(*inode));
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kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
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}
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if (ret > 0)
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file_update_time(filp);
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return ret;
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}
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static ssize_t
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pipe_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
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return pipe_writev(filp, &iov, 1, ppos);
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}
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static ssize_t
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bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
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{
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return -EBADF;
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}
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static ssize_t
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bad_pipe_w(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
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{
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return -EBADF;
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}
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static int
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pipe_ioctl(struct inode *pino, struct file *filp,
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unsigned int cmd, unsigned long arg)
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{
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struct inode *inode = filp->f_dentry->d_inode;
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struct pipe_inode_info *info;
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int count, buf, nrbufs;
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switch (cmd) {
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case FIONREAD:
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mutex_lock(PIPE_MUTEX(*inode));
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info = inode->i_pipe;
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count = 0;
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buf = info->curbuf;
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nrbufs = info->nrbufs;
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while (--nrbufs >= 0) {
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count += info->bufs[buf].len;
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buf = (buf+1) & (PIPE_BUFFERS-1);
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}
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mutex_unlock(PIPE_MUTEX(*inode));
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return put_user(count, (int __user *)arg);
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default:
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return -EINVAL;
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}
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}
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/* No kernel lock held - fine */
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static unsigned int
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pipe_poll(struct file *filp, poll_table *wait)
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{
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unsigned int mask;
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struct inode *inode = filp->f_dentry->d_inode;
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struct pipe_inode_info *info = inode->i_pipe;
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int nrbufs;
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poll_wait(filp, PIPE_WAIT(*inode), wait);
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/* Reading only -- no need for acquiring the semaphore. */
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nrbufs = info->nrbufs;
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mask = 0;
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if (filp->f_mode & FMODE_READ) {
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mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
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if (!PIPE_WRITERS(*inode) && filp->f_version != PIPE_WCOUNTER(*inode))
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mask |= POLLHUP;
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}
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if (filp->f_mode & FMODE_WRITE) {
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mask |= (nrbufs < PIPE_BUFFERS) ? POLLOUT | POLLWRNORM : 0;
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/*
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* Most Unices do not set POLLERR for FIFOs but on Linux they
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* behave exactly like pipes for poll().
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*/
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if (!PIPE_READERS(*inode))
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mask |= POLLERR;
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}
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return mask;
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}
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static int
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pipe_release(struct inode *inode, int decr, int decw)
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{
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mutex_lock(PIPE_MUTEX(*inode));
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PIPE_READERS(*inode) -= decr;
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PIPE_WRITERS(*inode) -= decw;
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if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) {
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free_pipe_info(inode);
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} else {
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wake_up_interruptible(PIPE_WAIT(*inode));
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kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
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kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
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}
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mutex_unlock(PIPE_MUTEX(*inode));
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return 0;
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}
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static int
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pipe_read_fasync(int fd, struct file *filp, int on)
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{
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struct inode *inode = filp->f_dentry->d_inode;
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int retval;
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mutex_lock(PIPE_MUTEX(*inode));
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retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
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mutex_unlock(PIPE_MUTEX(*inode));
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if (retval < 0)
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return retval;
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return 0;
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}
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static int
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pipe_write_fasync(int fd, struct file *filp, int on)
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{
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struct inode *inode = filp->f_dentry->d_inode;
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int retval;
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mutex_lock(PIPE_MUTEX(*inode));
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retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
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mutex_unlock(PIPE_MUTEX(*inode));
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if (retval < 0)
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return retval;
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return 0;
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}
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static int
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pipe_rdwr_fasync(int fd, struct file *filp, int on)
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{
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struct inode *inode = filp->f_dentry->d_inode;
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int retval;
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mutex_lock(PIPE_MUTEX(*inode));
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|
|
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
|
|
|
|
if (retval >= 0)
|
|
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
|
|
|
|
mutex_unlock(PIPE_MUTEX(*inode));
|
|
|
|
if (retval < 0)
|
|
return retval;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static int
|
|
pipe_read_release(struct inode *inode, struct file *filp)
|
|
{
|
|
pipe_read_fasync(-1, filp, 0);
|
|
return pipe_release(inode, 1, 0);
|
|
}
|
|
|
|
static int
|
|
pipe_write_release(struct inode *inode, struct file *filp)
|
|
{
|
|
pipe_write_fasync(-1, filp, 0);
|
|
return pipe_release(inode, 0, 1);
|
|
}
|
|
|
|
static int
|
|
pipe_rdwr_release(struct inode *inode, struct file *filp)
|
|
{
|
|
int decr, decw;
|
|
|
|
pipe_rdwr_fasync(-1, filp, 0);
|
|
decr = (filp->f_mode & FMODE_READ) != 0;
|
|
decw = (filp->f_mode & FMODE_WRITE) != 0;
|
|
return pipe_release(inode, decr, decw);
|
|
}
|
|
|
|
static int
|
|
pipe_read_open(struct inode *inode, struct file *filp)
|
|
{
|
|
/* We could have perhaps used atomic_t, but this and friends
|
|
below are the only places. So it doesn't seem worthwhile. */
|
|
mutex_lock(PIPE_MUTEX(*inode));
|
|
PIPE_READERS(*inode)++;
|
|
mutex_unlock(PIPE_MUTEX(*inode));
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
pipe_write_open(struct inode *inode, struct file *filp)
|
|
{
|
|
mutex_lock(PIPE_MUTEX(*inode));
|
|
PIPE_WRITERS(*inode)++;
|
|
mutex_unlock(PIPE_MUTEX(*inode));
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
pipe_rdwr_open(struct inode *inode, struct file *filp)
|
|
{
|
|
mutex_lock(PIPE_MUTEX(*inode));
|
|
if (filp->f_mode & FMODE_READ)
|
|
PIPE_READERS(*inode)++;
|
|
if (filp->f_mode & FMODE_WRITE)
|
|
PIPE_WRITERS(*inode)++;
|
|
mutex_unlock(PIPE_MUTEX(*inode));
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* The file_operations structs are not static because they
|
|
* are also used in linux/fs/fifo.c to do operations on FIFOs.
|
|
*/
|
|
const struct file_operations read_fifo_fops = {
|
|
.llseek = no_llseek,
|
|
.read = pipe_read,
|
|
.readv = pipe_readv,
|
|
.write = bad_pipe_w,
|
|
.poll = pipe_poll,
|
|
.ioctl = pipe_ioctl,
|
|
.open = pipe_read_open,
|
|
.release = pipe_read_release,
|
|
.fasync = pipe_read_fasync,
|
|
};
|
|
|
|
const struct file_operations write_fifo_fops = {
|
|
.llseek = no_llseek,
|
|
.read = bad_pipe_r,
|
|
.write = pipe_write,
|
|
.writev = pipe_writev,
|
|
.poll = pipe_poll,
|
|
.ioctl = pipe_ioctl,
|
|
.open = pipe_write_open,
|
|
.release = pipe_write_release,
|
|
.fasync = pipe_write_fasync,
|
|
};
|
|
|
|
const struct file_operations rdwr_fifo_fops = {
|
|
.llseek = no_llseek,
|
|
.read = pipe_read,
|
|
.readv = pipe_readv,
|
|
.write = pipe_write,
|
|
.writev = pipe_writev,
|
|
.poll = pipe_poll,
|
|
.ioctl = pipe_ioctl,
|
|
.open = pipe_rdwr_open,
|
|
.release = pipe_rdwr_release,
|
|
.fasync = pipe_rdwr_fasync,
|
|
};
|
|
|
|
static struct file_operations read_pipe_fops = {
|
|
.llseek = no_llseek,
|
|
.read = pipe_read,
|
|
.readv = pipe_readv,
|
|
.write = bad_pipe_w,
|
|
.poll = pipe_poll,
|
|
.ioctl = pipe_ioctl,
|
|
.open = pipe_read_open,
|
|
.release = pipe_read_release,
|
|
.fasync = pipe_read_fasync,
|
|
};
|
|
|
|
static struct file_operations write_pipe_fops = {
|
|
.llseek = no_llseek,
|
|
.read = bad_pipe_r,
|
|
.write = pipe_write,
|
|
.writev = pipe_writev,
|
|
.poll = pipe_poll,
|
|
.ioctl = pipe_ioctl,
|
|
.open = pipe_write_open,
|
|
.release = pipe_write_release,
|
|
.fasync = pipe_write_fasync,
|
|
};
|
|
|
|
static struct file_operations rdwr_pipe_fops = {
|
|
.llseek = no_llseek,
|
|
.read = pipe_read,
|
|
.readv = pipe_readv,
|
|
.write = pipe_write,
|
|
.writev = pipe_writev,
|
|
.poll = pipe_poll,
|
|
.ioctl = pipe_ioctl,
|
|
.open = pipe_rdwr_open,
|
|
.release = pipe_rdwr_release,
|
|
.fasync = pipe_rdwr_fasync,
|
|
};
|
|
|
|
void free_pipe_info(struct inode *inode)
|
|
{
|
|
int i;
|
|
struct pipe_inode_info *info = inode->i_pipe;
|
|
|
|
inode->i_pipe = NULL;
|
|
for (i = 0; i < PIPE_BUFFERS; i++) {
|
|
struct pipe_buffer *buf = info->bufs + i;
|
|
if (buf->ops)
|
|
buf->ops->release(info, buf);
|
|
}
|
|
if (info->tmp_page)
|
|
__free_page(info->tmp_page);
|
|
kfree(info);
|
|
}
|
|
|
|
struct inode* pipe_new(struct inode* inode)
|
|
{
|
|
struct pipe_inode_info *info;
|
|
|
|
info = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
|
|
if (!info)
|
|
goto fail_page;
|
|
inode->i_pipe = info;
|
|
|
|
init_waitqueue_head(PIPE_WAIT(*inode));
|
|
PIPE_RCOUNTER(*inode) = PIPE_WCOUNTER(*inode) = 1;
|
|
|
|
return inode;
|
|
fail_page:
|
|
return NULL;
|
|
}
|
|
|
|
static struct vfsmount *pipe_mnt __read_mostly;
|
|
static int pipefs_delete_dentry(struct dentry *dentry)
|
|
{
|
|
return 1;
|
|
}
|
|
static struct dentry_operations pipefs_dentry_operations = {
|
|
.d_delete = pipefs_delete_dentry,
|
|
};
|
|
|
|
static struct inode * get_pipe_inode(void)
|
|
{
|
|
struct inode *inode = new_inode(pipe_mnt->mnt_sb);
|
|
|
|
if (!inode)
|
|
goto fail_inode;
|
|
|
|
if(!pipe_new(inode))
|
|
goto fail_iput;
|
|
PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 1;
|
|
inode->i_fop = &rdwr_pipe_fops;
|
|
|
|
/*
|
|
* Mark the inode dirty from the very beginning,
|
|
* that way it will never be moved to the dirty
|
|
* list because "mark_inode_dirty()" will think
|
|
* that it already _is_ on the dirty list.
|
|
*/
|
|
inode->i_state = I_DIRTY;
|
|
inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR;
|
|
inode->i_uid = current->fsuid;
|
|
inode->i_gid = current->fsgid;
|
|
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
|
|
inode->i_blksize = PAGE_SIZE;
|
|
return inode;
|
|
|
|
fail_iput:
|
|
iput(inode);
|
|
fail_inode:
|
|
return NULL;
|
|
}
|
|
|
|
int do_pipe(int *fd)
|
|
{
|
|
struct qstr this;
|
|
char name[32];
|
|
struct dentry *dentry;
|
|
struct inode * inode;
|
|
struct file *f1, *f2;
|
|
int error;
|
|
int i,j;
|
|
|
|
error = -ENFILE;
|
|
f1 = get_empty_filp();
|
|
if (!f1)
|
|
goto no_files;
|
|
|
|
f2 = get_empty_filp();
|
|
if (!f2)
|
|
goto close_f1;
|
|
|
|
inode = get_pipe_inode();
|
|
if (!inode)
|
|
goto close_f12;
|
|
|
|
error = get_unused_fd();
|
|
if (error < 0)
|
|
goto close_f12_inode;
|
|
i = error;
|
|
|
|
error = get_unused_fd();
|
|
if (error < 0)
|
|
goto close_f12_inode_i;
|
|
j = error;
|
|
|
|
error = -ENOMEM;
|
|
sprintf(name, "[%lu]", inode->i_ino);
|
|
this.name = name;
|
|
this.len = strlen(name);
|
|
this.hash = inode->i_ino; /* will go */
|
|
dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &this);
|
|
if (!dentry)
|
|
goto close_f12_inode_i_j;
|
|
dentry->d_op = &pipefs_dentry_operations;
|
|
d_add(dentry, inode);
|
|
f1->f_vfsmnt = f2->f_vfsmnt = mntget(mntget(pipe_mnt));
|
|
f1->f_dentry = f2->f_dentry = dget(dentry);
|
|
f1->f_mapping = f2->f_mapping = inode->i_mapping;
|
|
|
|
/* read file */
|
|
f1->f_pos = f2->f_pos = 0;
|
|
f1->f_flags = O_RDONLY;
|
|
f1->f_op = &read_pipe_fops;
|
|
f1->f_mode = FMODE_READ;
|
|
f1->f_version = 0;
|
|
|
|
/* write file */
|
|
f2->f_flags = O_WRONLY;
|
|
f2->f_op = &write_pipe_fops;
|
|
f2->f_mode = FMODE_WRITE;
|
|
f2->f_version = 0;
|
|
|
|
fd_install(i, f1);
|
|
fd_install(j, f2);
|
|
fd[0] = i;
|
|
fd[1] = j;
|
|
return 0;
|
|
|
|
close_f12_inode_i_j:
|
|
put_unused_fd(j);
|
|
close_f12_inode_i:
|
|
put_unused_fd(i);
|
|
close_f12_inode:
|
|
free_pipe_info(inode);
|
|
iput(inode);
|
|
close_f12:
|
|
put_filp(f2);
|
|
close_f1:
|
|
put_filp(f1);
|
|
no_files:
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* pipefs should _never_ be mounted by userland - too much of security hassle,
|
|
* no real gain from having the whole whorehouse mounted. So we don't need
|
|
* any operations on the root directory. However, we need a non-trivial
|
|
* d_name - pipe: will go nicely and kill the special-casing in procfs.
|
|
*/
|
|
|
|
static struct super_block *pipefs_get_sb(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name, void *data)
|
|
{
|
|
return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC);
|
|
}
|
|
|
|
static struct file_system_type pipe_fs_type = {
|
|
.name = "pipefs",
|
|
.get_sb = pipefs_get_sb,
|
|
.kill_sb = kill_anon_super,
|
|
};
|
|
|
|
static int __init init_pipe_fs(void)
|
|
{
|
|
int err = register_filesystem(&pipe_fs_type);
|
|
if (!err) {
|
|
pipe_mnt = kern_mount(&pipe_fs_type);
|
|
if (IS_ERR(pipe_mnt)) {
|
|
err = PTR_ERR(pipe_mnt);
|
|
unregister_filesystem(&pipe_fs_type);
|
|
}
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static void __exit exit_pipe_fs(void)
|
|
{
|
|
unregister_filesystem(&pipe_fs_type);
|
|
mntput(pipe_mnt);
|
|
}
|
|
|
|
fs_initcall(init_pipe_fs);
|
|
module_exit(exit_pipe_fs);
|