From c1775d1a93a77a57380a4ce87ac3a8f807c944b2 Mon Sep 17 00:00:00 2001 From: Kim Kibum Date: Sun, 29 Apr 2012 16:59:19 +0900 Subject: upload tizen1.0 source --- fs/pipe.c | 1294 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1294 insertions(+) create mode 100644 fs/pipe.c (limited to 'fs/pipe.c') diff --git a/fs/pipe.c b/fs/pipe.c new file mode 100644 index 00000000..a58d7ee7 --- /dev/null +++ b/fs/pipe.c @@ -0,0 +1,1294 @@ +/* + * linux/fs/pipe.c + * + * Copyright (C) 1991, 1992, 1999 Linus Torvalds + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +/* + * The max size that a non-root user is allowed to grow the pipe. Can + * be set by root in /proc/sys/fs/pipe-max-size + */ +unsigned int pipe_max_size = 1048576; + +/* + * Minimum pipe size, as required by POSIX + */ +unsigned int pipe_min_size = PAGE_SIZE; + +/* + * 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 2001-08-16 + * + * pipe_read & write cleanup + * -- Manfred Spraul 2002-05-09 + */ + +static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass) +{ + if (pipe->inode) + mutex_lock_nested(&pipe->inode->i_mutex, subclass); +} + +void pipe_lock(struct pipe_inode_info *pipe) +{ + /* + * pipe_lock() nests non-pipe inode locks (for writing to a file) + */ + pipe_lock_nested(pipe, I_MUTEX_PARENT); +} +EXPORT_SYMBOL(pipe_lock); + +void pipe_unlock(struct pipe_inode_info *pipe) +{ + if (pipe->inode) + mutex_unlock(&pipe->inode->i_mutex); +} +EXPORT_SYMBOL(pipe_unlock); + +void pipe_double_lock(struct pipe_inode_info *pipe1, + struct pipe_inode_info *pipe2) +{ + BUG_ON(pipe1 == pipe2); + + if (pipe1 < pipe2) { + pipe_lock_nested(pipe1, I_MUTEX_PARENT); + pipe_lock_nested(pipe2, I_MUTEX_CHILD); + } else { + pipe_lock_nested(pipe2, I_MUTEX_PARENT); + pipe_lock_nested(pipe1, I_MUTEX_CHILD); + } +} + +/* Drop the inode semaphore and wait for a pipe event, atomically */ +void pipe_wait(struct pipe_inode_info *pipe) +{ + DEFINE_WAIT(wait); + + /* + * Pipes are system-local resources, so sleeping on them + * is considered a noninteractive wait: + */ + prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE); + pipe_unlock(pipe); + schedule(); + finish_wait(&pipe->wait, &wait); + pipe_lock(pipe); +} + +static int +pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len, + int atomic) +{ + unsigned long copy; + + while (len > 0) { + while (!iov->iov_len) + iov++; + copy = min_t(unsigned long, len, iov->iov_len); + + if (atomic) { + if (__copy_from_user_inatomic(to, iov->iov_base, copy)) + return -EFAULT; + } else { + 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 int +pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len, + int atomic) +{ + unsigned long copy; + + while (len > 0) { + while (!iov->iov_len) + iov++; + copy = min_t(unsigned long, len, iov->iov_len); + + if (atomic) { + if (__copy_to_user_inatomic(iov->iov_base, from, copy)) + return -EFAULT; + } else { + 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; +} + +/* + * Attempt to pre-fault in the user memory, so we can use atomic copies. + * Returns the number of bytes not faulted in. + */ +static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len) +{ + while (!iov->iov_len) + iov++; + + while (len > 0) { + unsigned long this_len; + + this_len = min_t(unsigned long, len, iov->iov_len); + if (fault_in_pages_writeable(iov->iov_base, this_len)) + break; + + len -= this_len; + iov++; + } + + return len; +} + +/* + * Pre-fault in the user memory, so we can use atomic copies. + */ +static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len) +{ + while (!iov->iov_len) + iov++; + + while (len > 0) { + unsigned long this_len; + + this_len = min_t(unsigned long, len, iov->iov_len); + fault_in_pages_readable(iov->iov_base, this_len); + len -= this_len; + iov++; + } +} + +static void anon_pipe_buf_release(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + struct page *page = buf->page; + + /* + * If nobody else uses this page, and we don't already have a + * temporary page, let's keep track of it as a one-deep + * allocation cache. (Otherwise just release our reference to it) + */ + if (page_count(page) == 1 && !pipe->tmp_page) + pipe->tmp_page = page; + else + page_cache_release(page); +} + +/** + * generic_pipe_buf_map - virtually map a pipe buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer that should be mapped + * @atomic: whether to use an atomic map + * + * Description: + * This function returns a kernel virtual address mapping for the + * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided + * and the caller has to be careful not to fault before calling + * the unmap function. + * + * Note that this function occupies KM_USER0 if @atomic != 0. + */ +void *generic_pipe_buf_map(struct pipe_inode_info *pipe, + struct pipe_buffer *buf, int atomic) +{ + if (atomic) { + buf->flags |= PIPE_BUF_FLAG_ATOMIC; + return kmap_atomic(buf->page, KM_USER0); + } + + return kmap(buf->page); +} +EXPORT_SYMBOL(generic_pipe_buf_map); + +/** + * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer that should be unmapped + * @map_data: the data that the mapping function returned + * + * Description: + * This function undoes the mapping that ->map() provided. + */ +void generic_pipe_buf_unmap(struct pipe_inode_info *pipe, + struct pipe_buffer *buf, void *map_data) +{ + if (buf->flags & PIPE_BUF_FLAG_ATOMIC) { + buf->flags &= ~PIPE_BUF_FLAG_ATOMIC; + kunmap_atomic(map_data, KM_USER0); + } else + kunmap(buf->page); +} +EXPORT_SYMBOL(generic_pipe_buf_unmap); + +/** + * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer to attempt to steal + * + * Description: + * This function attempts to steal the &struct page attached to + * @buf. If successful, this function returns 0 and returns with + * the page locked. The caller may then reuse the page for whatever + * he wishes; the typical use is insertion into a different file + * page cache. + */ +int generic_pipe_buf_steal(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + struct page *page = buf->page; + + /* + * A reference of one is golden, that means that the owner of this + * page is the only one holding a reference to it. lock the page + * and return OK. + */ + if (page_count(page) == 1) { + lock_page(page); + return 0; + } + + return 1; +} +EXPORT_SYMBOL(generic_pipe_buf_steal); + +/** + * generic_pipe_buf_get - get a reference to a &struct pipe_buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer to get a reference to + * + * Description: + * This function grabs an extra reference to @buf. It's used in + * in the tee() system call, when we duplicate the buffers in one + * pipe into another. + */ +void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) +{ + page_cache_get(buf->page); +} +EXPORT_SYMBOL(generic_pipe_buf_get); + +/** + * generic_pipe_buf_confirm - verify contents of the pipe buffer + * @info: the pipe that the buffer belongs to + * @buf: the buffer to confirm + * + * Description: + * This function does nothing, because the generic pipe code uses + * pages that are always good when inserted into the pipe. + */ +int generic_pipe_buf_confirm(struct pipe_inode_info *info, + struct pipe_buffer *buf) +{ + return 0; +} +EXPORT_SYMBOL(generic_pipe_buf_confirm); + +/** + * generic_pipe_buf_release - put a reference to a &struct pipe_buffer + * @pipe: the pipe that the buffer belongs to + * @buf: the buffer to put a reference to + * + * Description: + * This function releases a reference to @buf. + */ +void generic_pipe_buf_release(struct pipe_inode_info *pipe, + struct pipe_buffer *buf) +{ + page_cache_release(buf->page); +} +EXPORT_SYMBOL(generic_pipe_buf_release); + +static const struct pipe_buf_operations anon_pipe_buf_ops = { + .can_merge = 1, + .map = generic_pipe_buf_map, + .unmap = generic_pipe_buf_unmap, + .confirm = generic_pipe_buf_confirm, + .release = anon_pipe_buf_release, + .steal = generic_pipe_buf_steal, + .get = generic_pipe_buf_get, +}; + +static ssize_t +pipe_read(struct kiocb *iocb, const struct iovec *_iov, + unsigned long nr_segs, loff_t pos) +{ + struct file *filp = iocb->ki_filp; + struct inode *inode = filp->f_path.dentry->d_inode; + struct pipe_inode_info *pipe; + 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; + mutex_lock(&inode->i_mutex); + pipe = inode->i_pipe; + for (;;) { + int bufs = pipe->nrbufs; + if (bufs) { + int curbuf = pipe->curbuf; + struct pipe_buffer *buf = pipe->bufs + curbuf; + const struct pipe_buf_operations *ops = buf->ops; + void *addr; + size_t chars = buf->len; + int error, atomic; + + if (chars > total_len) + chars = total_len; + + error = ops->confirm(pipe, buf); + if (error) { + if (!ret) + ret = error; + break; + } + + atomic = !iov_fault_in_pages_write(iov, chars); +redo: + addr = ops->map(pipe, buf, atomic); + error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic); + ops->unmap(pipe, buf, addr); + if (unlikely(error)) { + /* + * Just retry with the slow path if we failed. + */ + if (atomic) { + atomic = 0; + goto redo; + } + if (!ret) + ret = error; + break; + } + ret += chars; + buf->offset += chars; + buf->len -= chars; + if (!buf->len) { + buf->ops = NULL; + ops->release(pipe, buf); + curbuf = (curbuf + 1) & (pipe->buffers - 1); + pipe->curbuf = curbuf; + pipe->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) + break; + if (!pipe->waiting_writers) { + /* 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); + kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); + } + pipe_wait(pipe); + } + mutex_unlock(&inode->i_mutex); + + /* Signal writers asynchronously that there is more room. */ + if (do_wakeup) { + wake_up_interruptible_sync(&pipe->wait); + kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); + } + if (ret > 0) + file_accessed(filp); + return ret; +} + +static ssize_t +pipe_write(struct kiocb *iocb, const struct iovec *_iov, + unsigned long nr_segs, loff_t ppos) +{ + struct file *filp = iocb->ki_filp; + struct inode *inode = filp->f_path.dentry->d_inode; + struct pipe_inode_info *pipe; + 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; + mutex_lock(&inode->i_mutex); + pipe = inode->i_pipe; + + if (!pipe->readers) { + 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 (pipe->nrbufs && chars != 0) { + int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) & + (pipe->buffers - 1); + struct pipe_buffer *buf = pipe->bufs + lastbuf; + const struct pipe_buf_operations *ops = buf->ops; + int offset = buf->offset + buf->len; + + if (ops->can_merge && offset + chars <= PAGE_SIZE) { + int error, atomic = 1; + void *addr; + + error = ops->confirm(pipe, buf); + if (error) + goto out; + + iov_fault_in_pages_read(iov, chars); +redo1: + addr = ops->map(pipe, buf, atomic); + error = pipe_iov_copy_from_user(offset + addr, iov, + chars, atomic); + ops->unmap(pipe, buf, addr); + ret = error; + do_wakeup = 1; + if (error) { + if (atomic) { + atomic = 0; + goto redo1; + } + goto out; + } + buf->len += chars; + total_len -= chars; + ret = chars; + if (!total_len) + goto out; + } + } + + for (;;) { + int bufs; + + if (!pipe->readers) { + send_sig(SIGPIPE, current, 0); + if (!ret) + ret = -EPIPE; + break; + } + bufs = pipe->nrbufs; + if (bufs < pipe->buffers) { + int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1); + struct pipe_buffer *buf = pipe->bufs + newbuf; + struct page *page = pipe->tmp_page; + char *src; + int error, atomic = 1; + + if (!page) { + page = alloc_page(GFP_HIGHUSER); + if (unlikely(!page)) { + ret = ret ? : -ENOMEM; + break; + } + pipe->tmp_page = page; + } + /* Always wake up, 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; + + iov_fault_in_pages_read(iov, chars); +redo2: + if (atomic) + src = kmap_atomic(page, KM_USER0); + else + src = kmap(page); + + error = pipe_iov_copy_from_user(src, iov, chars, + atomic); + if (atomic) + kunmap_atomic(src, KM_USER0); + else + kunmap(page); + + if (unlikely(error)) { + if (atomic) { + atomic = 0; + goto redo2; + } + if (!ret) + ret = error; + break; + } + ret += chars; + + /* Insert it into the buffer array */ + buf->page = page; + buf->ops = &anon_pipe_buf_ops; + buf->offset = 0; + buf->len = chars; + pipe->nrbufs = ++bufs; + pipe->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); + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); + do_wakeup = 0; + } + pipe->waiting_writers++; + pipe_wait(pipe); + pipe->waiting_writers--; + } +out: + mutex_unlock(&inode->i_mutex); + if (do_wakeup) { + wake_up_interruptible_sync(&pipe->wait); + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); + } + if (ret > 0) + file_update_time(filp); + return ret; +} + +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 long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) +{ + struct inode *inode = filp->f_path.dentry->d_inode; + struct pipe_inode_info *pipe; + int count, buf, nrbufs; + + switch (cmd) { + case FIONREAD: + mutex_lock(&inode->i_mutex); + pipe = inode->i_pipe; + count = 0; + buf = pipe->curbuf; + nrbufs = pipe->nrbufs; + while (--nrbufs >= 0) { + count += pipe->bufs[buf].len; + buf = (buf+1) & (pipe->buffers - 1); + } + mutex_unlock(&inode->i_mutex); + + 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_path.dentry->d_inode; + struct pipe_inode_info *pipe = inode->i_pipe; + int nrbufs; + + poll_wait(filp, &pipe->wait, wait); + + /* Reading only -- no need for acquiring the semaphore. */ + nrbufs = pipe->nrbufs; + mask = 0; + if (filp->f_mode & FMODE_READ) { + mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0; + if (!pipe->writers && filp->f_version != pipe->w_counter) + mask |= POLLHUP; + } + + if (filp->f_mode & FMODE_WRITE) { + mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0; + /* + * Most Unices do not set POLLERR for FIFOs but on Linux they + * behave exactly like pipes for poll(). + */ + if (!pipe->readers) + mask |= POLLERR; + } + + return mask; +} + +static int +pipe_release(struct inode *inode, int decr, int decw) +{ + struct pipe_inode_info *pipe; + + mutex_lock(&inode->i_mutex); + pipe = inode->i_pipe; + pipe->readers -= decr; + pipe->writers -= decw; + + if (!pipe->readers && !pipe->writers) { + free_pipe_info(inode); + } else { + wake_up_interruptible_sync(&pipe->wait); + kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); + kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); + } + mutex_unlock(&inode->i_mutex); + + return 0; +} + +static int +pipe_read_fasync(int fd, struct file *filp, int on) +{ + struct inode *inode = filp->f_path.dentry->d_inode; + int retval; + + mutex_lock(&inode->i_mutex); + retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers); + mutex_unlock(&inode->i_mutex); + + return retval; +} + + +static int +pipe_write_fasync(int fd, struct file *filp, int on) +{ + struct inode *inode = filp->f_path.dentry->d_inode; + int retval; + + mutex_lock(&inode->i_mutex); + retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers); + mutex_unlock(&inode->i_mutex); + + return retval; +} + + +static int +pipe_rdwr_fasync(int fd, struct file *filp, int on) +{ + struct inode *inode = filp->f_path.dentry->d_inode; + struct pipe_inode_info *pipe = inode->i_pipe; + int retval; + + mutex_lock(&inode->i_mutex); + retval = fasync_helper(fd, filp, on, &pipe->fasync_readers); + if (retval >= 0) { + retval = fasync_helper(fd, filp, on, &pipe->fasync_writers); + if (retval < 0) /* this can happen only if on == T */ + fasync_helper(-1, filp, 0, &pipe->fasync_readers); + } + mutex_unlock(&inode->i_mutex); + return retval; +} + + +static int +pipe_read_release(struct inode *inode, struct file *filp) +{ + return pipe_release(inode, 1, 0); +} + +static int +pipe_write_release(struct inode *inode, struct file *filp) +{ + return pipe_release(inode, 0, 1); +} + +static int +pipe_rdwr_release(struct inode *inode, struct file *filp) +{ + int decr, decw; + + 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) +{ + int ret = -ENOENT; + + mutex_lock(&inode->i_mutex); + + if (inode->i_pipe) { + ret = 0; + inode->i_pipe->readers++; + } + + mutex_unlock(&inode->i_mutex); + + return ret; +} + +static int +pipe_write_open(struct inode *inode, struct file *filp) +{ + int ret = -ENOENT; + + mutex_lock(&inode->i_mutex); + + if (inode->i_pipe) { + ret = 0; + inode->i_pipe->writers++; + } + + mutex_unlock(&inode->i_mutex); + + return ret; +} + +static int +pipe_rdwr_open(struct inode *inode, struct file *filp) +{ + int ret = -ENOENT; + + mutex_lock(&inode->i_mutex); + + if (inode->i_pipe) { + ret = 0; + if (filp->f_mode & FMODE_READ) + inode->i_pipe->readers++; + if (filp->f_mode & FMODE_WRITE) + inode->i_pipe->writers++; + } + + mutex_unlock(&inode->i_mutex); + + return ret; +} + +/* + * The file_operations structs are not static because they + * are also used in linux/fs/fifo.c to do operations on FIFOs. + * + * Pipes reuse fifos' file_operations structs. + */ +const struct file_operations read_pipefifo_fops = { + .llseek = no_llseek, + .read = do_sync_read, + .aio_read = pipe_read, + .write = bad_pipe_w, + .poll = pipe_poll, + .unlocked_ioctl = pipe_ioctl, + .open = pipe_read_open, + .release = pipe_read_release, + .fasync = pipe_read_fasync, +}; + +const struct file_operations write_pipefifo_fops = { + .llseek = no_llseek, + .read = bad_pipe_r, + .write = do_sync_write, + .aio_write = pipe_write, + .poll = pipe_poll, + .unlocked_ioctl = pipe_ioctl, + .open = pipe_write_open, + .release = pipe_write_release, + .fasync = pipe_write_fasync, +}; + +const struct file_operations rdwr_pipefifo_fops = { + .llseek = no_llseek, + .read = do_sync_read, + .aio_read = pipe_read, + .write = do_sync_write, + .aio_write = pipe_write, + .poll = pipe_poll, + .unlocked_ioctl = pipe_ioctl, + .open = pipe_rdwr_open, + .release = pipe_rdwr_release, + .fasync = pipe_rdwr_fasync, +}; + +struct pipe_inode_info * alloc_pipe_info(struct inode *inode) +{ + struct pipe_inode_info *pipe; + + pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); + if (pipe) { + pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL); + if (pipe->bufs) { + init_waitqueue_head(&pipe->wait); + pipe->r_counter = pipe->w_counter = 1; + pipe->inode = inode; + pipe->buffers = PIPE_DEF_BUFFERS; + return pipe; + } + kfree(pipe); + } + + return NULL; +} + +void __free_pipe_info(struct pipe_inode_info *pipe) +{ + int i; + + for (i = 0; i < pipe->buffers; i++) { + struct pipe_buffer *buf = pipe->bufs + i; + if (buf->ops) + buf->ops->release(pipe, buf); + } + if (pipe->tmp_page) + __free_page(pipe->tmp_page); + kfree(pipe->bufs); + kfree(pipe); +} + +void free_pipe_info(struct inode *inode) +{ + __free_pipe_info(inode->i_pipe); + inode->i_pipe = NULL; +} + +static struct vfsmount *pipe_mnt __read_mostly; + +/* + * pipefs_dname() is called from d_path(). + */ +static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen) +{ + return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", + dentry->d_inode->i_ino); +} + +static const struct dentry_operations pipefs_dentry_operations = { + .d_dname = pipefs_dname, +}; + +static struct inode * get_pipe_inode(void) +{ + struct inode *inode = new_inode(pipe_mnt->mnt_sb); + struct pipe_inode_info *pipe; + + if (!inode) + goto fail_inode; + + pipe = alloc_pipe_info(inode); + if (!pipe) + goto fail_iput; + inode->i_pipe = pipe; + + pipe->readers = pipe->writers = 1; + inode->i_fop = &rdwr_pipefifo_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; + + return inode; + +fail_iput: + iput(inode); + +fail_inode: + return NULL; +} + +struct file *create_write_pipe(int flags) +{ + int err; + struct inode *inode; + struct file *f; + struct path path; + struct qstr name = { .name = "" }; + + err = -ENFILE; + inode = get_pipe_inode(); + if (!inode) + goto err; + + err = -ENOMEM; + path.dentry = d_alloc(pipe_mnt->mnt_sb->s_root, &name); + if (!path.dentry) + goto err_inode; + path.mnt = mntget(pipe_mnt); + + path.dentry->d_op = &pipefs_dentry_operations; + d_instantiate(path.dentry, inode); + + err = -ENFILE; + f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops); + if (!f) + goto err_dentry; + f->f_mapping = inode->i_mapping; + + f->f_flags = O_WRONLY | (flags & O_NONBLOCK); + f->f_version = 0; + + return f; + + err_dentry: + free_pipe_info(inode); + path_put(&path); + return ERR_PTR(err); + + err_inode: + free_pipe_info(inode); + iput(inode); + err: + return ERR_PTR(err); +} + +void free_write_pipe(struct file *f) +{ + free_pipe_info(f->f_dentry->d_inode); + path_put(&f->f_path); + put_filp(f); +} + +struct file *create_read_pipe(struct file *wrf, int flags) +{ + /* Grab pipe from the writer */ + struct file *f = alloc_file(&wrf->f_path, FMODE_READ, + &read_pipefifo_fops); + if (!f) + return ERR_PTR(-ENFILE); + + path_get(&wrf->f_path); + f->f_flags = O_RDONLY | (flags & O_NONBLOCK); + + return f; +} + +int do_pipe_flags(int *fd, int flags) +{ + struct file *fw, *fr; + int error; + int fdw, fdr; + + if (flags & ~(O_CLOEXEC | O_NONBLOCK)) + return -EINVAL; + + fw = create_write_pipe(flags); + if (IS_ERR(fw)) + return PTR_ERR(fw); + fr = create_read_pipe(fw, flags); + error = PTR_ERR(fr); + if (IS_ERR(fr)) + goto err_write_pipe; + + error = get_unused_fd_flags(flags); + if (error < 0) + goto err_read_pipe; + fdr = error; + + error = get_unused_fd_flags(flags); + if (error < 0) + goto err_fdr; + fdw = error; + + audit_fd_pair(fdr, fdw); + fd_install(fdr, fr); + fd_install(fdw, fw); + fd[0] = fdr; + fd[1] = fdw; + + return 0; + + err_fdr: + put_unused_fd(fdr); + err_read_pipe: + path_put(&fr->f_path); + put_filp(fr); + err_write_pipe: + free_write_pipe(fw); + return error; +} + +/* + * sys_pipe() is the normal C calling standard for creating + * a pipe. It's not the way Unix traditionally does this, though. + */ +SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags) +{ + int fd[2]; + int error; + + error = do_pipe_flags(fd, flags); + if (!error) { + if (copy_to_user(fildes, fd, sizeof(fd))) { + sys_close(fd[0]); + sys_close(fd[1]); + error = -EFAULT; + } + } + return error; +} + +SYSCALL_DEFINE1(pipe, int __user *, fildes) +{ + return sys_pipe2(fildes, 0); +} + +/* + * Allocate a new array of pipe buffers and copy the info over. Returns the + * pipe size if successful, or return -ERROR on error. + */ +static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) +{ + struct pipe_buffer *bufs; + + /* + * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't + * expect a lot of shrink+grow operations, just free and allocate + * again like we would do for growing. If the pipe currently + * contains more buffers than arg, then return busy. + */ + if (nr_pages < pipe->nrbufs) + return -EBUSY; + + bufs = kcalloc(nr_pages, sizeof(struct pipe_buffer), GFP_KERNEL); + if (unlikely(!bufs)) + return -ENOMEM; + + /* + * The pipe array wraps around, so just start the new one at zero + * and adjust the indexes. + */ + if (pipe->nrbufs) { + unsigned int tail; + unsigned int head; + + tail = pipe->curbuf + pipe->nrbufs; + if (tail < pipe->buffers) + tail = 0; + else + tail &= (pipe->buffers - 1); + + head = pipe->nrbufs - tail; + if (head) + memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer)); + if (tail) + memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer)); + } + + pipe->curbuf = 0; + kfree(pipe->bufs); + pipe->bufs = bufs; + pipe->buffers = nr_pages; + return nr_pages * PAGE_SIZE; +} + +/* + * Currently we rely on the pipe array holding a power-of-2 number + * of pages. + */ +static inline unsigned int round_pipe_size(unsigned int size) +{ + unsigned long nr_pages; + + nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; + return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; +} + +/* + * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax + * will return an error. + */ +int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf, + size_t *lenp, loff_t *ppos) +{ + int ret; + + ret = proc_dointvec_minmax(table, write, buf, lenp, ppos); + if (ret < 0 || !write) + return ret; + + pipe_max_size = round_pipe_size(pipe_max_size); + return ret; +} + +/* + * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same + * location, so checking ->i_pipe is not enough to verify that this is a + * pipe. + */ +struct pipe_inode_info *get_pipe_info(struct file *file) +{ + struct inode *i = file->f_path.dentry->d_inode; + + return S_ISFIFO(i->i_mode) ? i->i_pipe : NULL; +} + +long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct pipe_inode_info *pipe; + long ret; + + pipe = get_pipe_info(file); + if (!pipe) + return -EBADF; + + mutex_lock(&pipe->inode->i_mutex); + + switch (cmd) { + case F_SETPIPE_SZ: { + unsigned int size, nr_pages; + + size = round_pipe_size(arg); + nr_pages = size >> PAGE_SHIFT; + + ret = -EINVAL; + if (!nr_pages) + goto out; + + if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) { + ret = -EPERM; + goto out; + } + ret = pipe_set_size(pipe, nr_pages); + break; + } + case F_GETPIPE_SZ: + ret = pipe->buffers * PAGE_SIZE; + break; + default: + ret = -EINVAL; + break; + } + +out: + mutex_unlock(&pipe->inode->i_mutex); + return ret; +} + +/* + * 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 int pipefs_get_sb(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data, + struct vfsmount *mnt) +{ + return get_sb_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC, mnt); +} + +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); -- cgit v1.2.3