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OpenCloudOS-Kernel/fs/pipe.c

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/*
* linux/fs/pipe.c
*
* Copyright (C) 1991, 1992, 1999 Linus Torvalds
*/
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pipe_fs_i.h>
#include <linux/uio.h>
#include <linux/highmem.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
/*
* We use a start+len construction, which provides full use of the
* allocated memory.
* -- Florian Coosmann (FGC)
*
* Reads with count = 0 should always return 0.
* -- Julian Bradfield 1999-06-07.
*
* FIFOs and Pipes now generate SIGIO for both readers and writers.
* -- Jeremy Elson <jelson@circlemud.org> 2001-08-16
*
* pipe_read & write cleanup
* -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
*/
/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct inode * inode)
{
DEFINE_WAIT(wait);
prepare_to_wait(PIPE_WAIT(*inode), &wait, TASK_INTERRUPTIBLE);
up(PIPE_SEM(*inode));
schedule();
finish_wait(PIPE_WAIT(*inode), &wait);
down(PIPE_SEM(*inode));
}
static inline int
pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len)
{
unsigned long copy;
while (len > 0) {
while (!iov->iov_len)
iov++;
copy = min_t(unsigned long, len, iov->iov_len);
if (copy_from_user(to, iov->iov_base, copy))
return -EFAULT;
to += copy;
len -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
return 0;
}
static inline int
pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len)
{
unsigned long copy;
while (len > 0) {
while (!iov->iov_len)
iov++;
copy = min_t(unsigned long, len, iov->iov_len);
if (copy_to_user(iov->iov_base, from, copy))
return -EFAULT;
from += copy;
len -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
return 0;
}
static void anon_pipe_buf_release(struct pipe_inode_info *info, struct pipe_buffer *buf)
{
struct page *page = buf->page;
if (info->tmp_page) {
__free_page(page);
return;
}
info->tmp_page = page;
}
static void *anon_pipe_buf_map(struct file *file, struct pipe_inode_info *info, struct pipe_buffer *buf)
{
return kmap(buf->page);
}
static void anon_pipe_buf_unmap(struct pipe_inode_info *info, struct pipe_buffer *buf)
{
kunmap(buf->page);
}
static struct pipe_buf_operations anon_pipe_buf_ops = {
.can_merge = 1,
.map = anon_pipe_buf_map,
.unmap = anon_pipe_buf_unmap,
.release = anon_pipe_buf_release,
};
static ssize_t
pipe_readv(struct file *filp, const struct iovec *_iov,
unsigned long nr_segs, loff_t *ppos)
{
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *info;
int do_wakeup;
ssize_t ret;
struct iovec *iov = (struct iovec *)_iov;
size_t total_len;
total_len = iov_length(iov, nr_segs);
/* Null read succeeds. */
if (unlikely(total_len == 0))
return 0;
do_wakeup = 0;
ret = 0;
down(PIPE_SEM(*inode));
info = inode->i_pipe;
for (;;) {
int bufs = info->nrbufs;
if (bufs) {
int curbuf = info->curbuf;
struct pipe_buffer *buf = info->bufs + curbuf;
struct pipe_buf_operations *ops = buf->ops;
void *addr;
size_t chars = buf->len;
int error;
if (chars > total_len)
chars = total_len;
addr = ops->map(filp, info, buf);
error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars);
ops->unmap(info, buf);
if (unlikely(error)) {
if (!ret) ret = -EFAULT;
break;
}
ret += chars;
buf->offset += chars;
buf->len -= chars;
if (!buf->len) {
buf->ops = NULL;
ops->release(info, buf);
curbuf = (curbuf + 1) & (PIPE_BUFFERS-1);
info->curbuf = curbuf;
info->nrbufs = --bufs;
do_wakeup = 1;
}
total_len -= chars;
if (!total_len)
break; /* common path: read succeeded */
}
if (bufs) /* More to do? */
continue;
if (!PIPE_WRITERS(*inode))
break;
if (!PIPE_WAITING_WRITERS(*inode)) {
/* syscall merging: Usually we must not sleep
* if O_NONBLOCK is set, or if we got some data.
* But if a writer sleeps in kernel space, then
* we can wait for that data without violating POSIX.
*/
if (ret)
break;
if (filp->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
break;
}
}
if (signal_pending(current)) {
if (!ret) ret = -ERESTARTSYS;
break;
}
if (do_wakeup) {
wake_up_interruptible_sync(PIPE_WAIT(*inode));
kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
}
pipe_wait(inode);
}
up(PIPE_SEM(*inode));
/* Signal writers asynchronously that there is more room. */
if (do_wakeup) {
wake_up_interruptible(PIPE_WAIT(*inode));
kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
}
if (ret > 0)
file_accessed(filp);
return ret;
}
static ssize_t
pipe_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
struct iovec iov = { .iov_base = buf, .iov_len = count };
return pipe_readv(filp, &iov, 1, ppos);
}
static ssize_t
pipe_writev(struct file *filp, const struct iovec *_iov,
unsigned long nr_segs, loff_t *ppos)
{
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *info;
ssize_t ret;
int do_wakeup;
struct iovec *iov = (struct iovec *)_iov;
size_t total_len;
ssize_t chars;
total_len = iov_length(iov, nr_segs);
/* Null write succeeds. */
if (unlikely(total_len == 0))
return 0;
do_wakeup = 0;
ret = 0;
down(PIPE_SEM(*inode));
info = inode->i_pipe;
if (!PIPE_READERS(*inode)) {
send_sig(SIGPIPE, current, 0);
ret = -EPIPE;
goto out;
}
/* We try to merge small writes */
chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
if (info->nrbufs && chars != 0) {
int lastbuf = (info->curbuf + info->nrbufs - 1) & (PIPE_BUFFERS-1);
struct pipe_buffer *buf = info->bufs + lastbuf;
struct pipe_buf_operations *ops = buf->ops;
int offset = buf->offset + buf->len;
if (ops->can_merge && offset + chars <= PAGE_SIZE) {
void *addr = ops->map(filp, info, buf);
int error = pipe_iov_copy_from_user(offset + addr, iov, chars);
ops->unmap(info, buf);
ret = error;
do_wakeup = 1;
if (error)
goto out;
buf->len += chars;
total_len -= chars;
ret = chars;
if (!total_len)
goto out;
}
}
for (;;) {
int bufs;
if (!PIPE_READERS(*inode)) {
send_sig(SIGPIPE, current, 0);
if (!ret) ret = -EPIPE;
break;
}
bufs = info->nrbufs;
if (bufs < PIPE_BUFFERS) {
int newbuf = (info->curbuf + bufs) & (PIPE_BUFFERS-1);
struct pipe_buffer *buf = info->bufs + newbuf;
struct page *page = info->tmp_page;
int error;
if (!page) {
page = alloc_page(GFP_HIGHUSER);
if (unlikely(!page)) {
ret = ret ? : -ENOMEM;
break;
}
info->tmp_page = page;
}
/* Always wakeup, even if the copy fails. Otherwise
* we lock up (O_NONBLOCK-)readers that sleep due to
* syscall merging.
* FIXME! Is this really true?
*/
do_wakeup = 1;
chars = PAGE_SIZE;
if (chars > total_len)
chars = total_len;
error = pipe_iov_copy_from_user(kmap(page), iov, chars);
kunmap(page);
if (unlikely(error)) {
if (!ret) ret = -EFAULT;
break;
}
ret += chars;
/* Insert it into the buffer array */
buf->page = page;
buf->ops = &anon_pipe_buf_ops;
buf->offset = 0;
buf->len = chars;
info->nrbufs = ++bufs;
info->tmp_page = NULL;
total_len -= chars;
if (!total_len)
break;
}
if (bufs < PIPE_BUFFERS)
continue;
if (filp->f_flags & O_NONBLOCK) {
if (!ret) ret = -EAGAIN;
break;
}
if (signal_pending(current)) {
if (!ret) ret = -ERESTARTSYS;
break;
}
if (do_wakeup) {
wake_up_interruptible_sync(PIPE_WAIT(*inode));
kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
do_wakeup = 0;
}
PIPE_WAITING_WRITERS(*inode)++;
pipe_wait(inode);
PIPE_WAITING_WRITERS(*inode)--;
}
out:
up(PIPE_SEM(*inode));
if (do_wakeup) {
wake_up_interruptible(PIPE_WAIT(*inode));
kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
}
if (ret > 0)
inode_update_time(inode, 1); /* mtime and ctime */
return ret;
}
static ssize_t
pipe_write(struct file *filp, const char __user *buf,
size_t count, loff_t *ppos)
{
struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = count };
return pipe_writev(filp, &iov, 1, ppos);
}
static ssize_t
bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
return -EBADF;
}
static ssize_t
bad_pipe_w(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
{
return -EBADF;
}
static int
pipe_ioctl(struct inode *pino, struct file *filp,
unsigned int cmd, unsigned long arg)
{
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *info;
int count, buf, nrbufs;
switch (cmd) {
case FIONREAD:
down(PIPE_SEM(*inode));
info = inode->i_pipe;
count = 0;
buf = info->curbuf;
nrbufs = info->nrbufs;
while (--nrbufs >= 0) {
count += info->bufs[buf].len;
buf = (buf+1) & (PIPE_BUFFERS-1);
}
up(PIPE_SEM(*inode));
return put_user(count, (int __user *)arg);
default:
return -EINVAL;
}
}
/* No kernel lock held - fine */
static unsigned int
pipe_poll(struct file *filp, poll_table *wait)
{
unsigned int mask;
struct inode *inode = filp->f_dentry->d_inode;
struct pipe_inode_info *info = inode->i_pipe;
int nrbufs;
poll_wait(filp, PIPE_WAIT(*inode), wait);
/* Reading only -- no need for acquiring the semaphore. */
nrbufs = info->nrbufs;
mask = 0;
if (filp->f_mode & FMODE_READ) {
mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0;
if (!PIPE_WRITERS(*inode) && filp->f_version != PIPE_WCOUNTER(*inode))
mask |= POLLHUP;
}
if (filp->f_mode & FMODE_WRITE) {
mask |= (nrbufs < PIPE_BUFFERS) ? POLLOUT | POLLWRNORM : 0;
if (!PIPE_READERS(*inode))
mask |= POLLERR;
}
return mask;
}
/* FIXME: most Unices do not set POLLERR for fifos */
#define fifo_poll pipe_poll
static int
pipe_release(struct inode *inode, int decr, int decw)
{
down(PIPE_SEM(*inode));
PIPE_READERS(*inode) -= decr;
PIPE_WRITERS(*inode) -= decw;
if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) {
free_pipe_info(inode);
} else {
wake_up_interruptible(PIPE_WAIT(*inode));
kill_fasync(PIPE_FASYNC_READERS(*inode), SIGIO, POLL_IN);
kill_fasync(PIPE_FASYNC_WRITERS(*inode), SIGIO, POLL_OUT);
}
up(PIPE_SEM(*inode));
return 0;
}
static int
pipe_read_fasync(int fd, struct file *filp, int on)
{
struct inode *inode = filp->f_dentry->d_inode;
int retval;
down(PIPE_SEM(*inode));
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
up(PIPE_SEM(*inode));
if (retval < 0)
return retval;
return 0;
}
static int
pipe_write_fasync(int fd, struct file *filp, int on)
{
struct inode *inode = filp->f_dentry->d_inode;
int retval;
down(PIPE_SEM(*inode));
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
up(PIPE_SEM(*inode));
if (retval < 0)
return retval;
return 0;
}
static int
pipe_rdwr_fasync(int fd, struct file *filp, int on)
{
struct inode *inode = filp->f_dentry->d_inode;
int retval;
down(PIPE_SEM(*inode));
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_READERS(*inode));
if (retval >= 0)
retval = fasync_helper(fd, filp, on, PIPE_FASYNC_WRITERS(*inode));
up(PIPE_SEM(*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. */
down(PIPE_SEM(*inode));
PIPE_READERS(*inode)++;
up(PIPE_SEM(*inode));
return 0;
}
static int
pipe_write_open(struct inode *inode, struct file *filp)
{
down(PIPE_SEM(*inode));
PIPE_WRITERS(*inode)++;
up(PIPE_SEM(*inode));
return 0;
}
static int
pipe_rdwr_open(struct inode *inode, struct file *filp)
{
down(PIPE_SEM(*inode));
if (filp->f_mode & FMODE_READ)
PIPE_READERS(*inode)++;
if (filp->f_mode & FMODE_WRITE)
PIPE_WRITERS(*inode)++;
up(PIPE_SEM(*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.
*/
struct file_operations read_fifo_fops = {
.llseek = no_llseek,
.read = pipe_read,
.readv = pipe_readv,
.write = bad_pipe_w,
.poll = fifo_poll,
.ioctl = pipe_ioctl,
.open = pipe_read_open,
.release = pipe_read_release,
.fasync = pipe_read_fasync,
};
struct file_operations write_fifo_fops = {
.llseek = no_llseek,
.read = bad_pipe_r,
.write = pipe_write,
.writev = pipe_writev,
.poll = fifo_poll,
.ioctl = pipe_ioctl,
.open = pipe_write_open,
.release = pipe_write_release,
.fasync = pipe_write_fasync,
};
struct file_operations rdwr_fifo_fops = {
.llseek = no_llseek,
.read = pipe_read,
.readv = pipe_readv,
.write = pipe_write,
.writev = pipe_writev,
.poll = fifo_poll,
.ioctl = pipe_ioctl,
.open = pipe_rdwr_open,
.release = pipe_rdwr_release,
.fasync = pipe_rdwr_fasync,
};
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,
};
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,
};
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 = kmalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
if (!info)
goto fail_page;
memset(info, 0, sizeof(*info));
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;
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);
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