diff options
| -rw-r--r-- | fs/splice.c | 142 |
1 files changed, 138 insertions, 4 deletions
diff --git a/fs/splice.c b/fs/splice.c index 3bd9cb21b38..eefd96b1d7f 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -535,6 +535,21 @@ static ssize_t kernel_readv(struct file *file, const struct iovec *vec, return res; } +static ssize_t kernel_writev(struct file *file, const struct iovec *vec, + unsigned long vlen, loff_t *ppos) +{ + mm_segment_t old_fs; + ssize_t res; + + old_fs = get_fs(); + set_fs(get_ds()); + /* The cast to a user pointer is valid due to the set_fs() */ + res = vfs_writev(file, (const struct iovec __user *)vec, vlen, ppos); + set_fs(old_fs); + + return res; +} + ssize_t default_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) @@ -988,6 +1003,122 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, EXPORT_SYMBOL(generic_file_splice_write); +static struct pipe_buffer *nth_pipe_buf(struct pipe_inode_info *pipe, int n) +{ + return &pipe->bufs[(pipe->curbuf + n) % PIPE_BUFFERS]; +} + +static ssize_t default_file_splice_write(struct pipe_inode_info *pipe, + struct file *out, loff_t *ppos, + size_t len, unsigned int flags) +{ + ssize_t ret = 0; + ssize_t total_len = 0; + int do_wakeup = 0; + + pipe_lock(pipe); + while (len) { + struct pipe_buffer *buf; + void *data[PIPE_BUFFERS]; + struct iovec vec[PIPE_BUFFERS]; + unsigned int nr_pages = 0; + unsigned int write_len = 0; + unsigned int now_len = len; + unsigned int this_len; + int i; + + BUG_ON(pipe->nrbufs > PIPE_BUFFERS); + for (i = 0; i < pipe->nrbufs && now_len; i++) { + buf = nth_pipe_buf(pipe, i); + + ret = buf->ops->confirm(pipe, buf); + if (ret) + break; + + data[i] = buf->ops->map(pipe, buf, 0); + this_len = min(buf->len, now_len); + vec[i].iov_base = (void __user *) data[i] + buf->offset; + vec[i].iov_len = this_len; + now_len -= this_len; + write_len += this_len; + nr_pages++; + } + + if (nr_pages) { + ret = kernel_writev(out, vec, nr_pages, ppos); + if (ret == 0) + ret = -EIO; + if (ret > 0) { + len -= ret; + total_len += ret; + } + } + + for (i = 0; i < nr_pages; i++) { + buf = nth_pipe_buf(pipe, i); + buf->ops->unmap(pipe, buf, data[i]); + + if (ret > 0) { + this_len = min_t(unsigned, vec[i].iov_len, ret); + buf->offset += this_len; + buf->len -= this_len; + ret -= this_len; + } + } + + if (ret < 0) + break; + + while (pipe->nrbufs) { + const struct pipe_buf_operations *ops; + + buf = nth_pipe_buf(pipe, 0); + if (buf->len) + break; + + ops = buf->ops; + buf->ops = NULL; + ops->release(pipe, buf); + pipe->curbuf = (pipe->curbuf + 1) % PIPE_BUFFERS; + pipe->nrbufs--; + if (pipe->inode) + do_wakeup = 1; + } + + if (pipe->nrbufs) + continue; + if (!pipe->writers) + break; + if (!pipe->waiting_writers) { + if (total_len) + break; + } + + if (flags & SPLICE_F_NONBLOCK) { + ret = -EAGAIN; + break; + } + + if (signal_pending(current)) { + ret = -ERESTARTSYS; + break; + } + + if (do_wakeup) { + wakeup_pipe_writers(pipe); + do_wakeup = 0; + } + + pipe_wait(pipe); + } + pipe_unlock(pipe); + + if (do_wakeup) + wakeup_pipe_writers(pipe); + + return total_len ? total_len : ret; +} + /** * generic_splice_sendpage - splice data from a pipe to a socket * @pipe: pipe to splice from @@ -1015,11 +1146,10 @@ EXPORT_SYMBOL(generic_splice_sendpage); static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags) { + ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, + loff_t *, size_t, unsigned int); int ret; - if (unlikely(!out->f_op || !out->f_op->splice_write)) - return -EINVAL; - if (unlikely(!(out->f_mode & FMODE_WRITE))) return -EBADF; @@ -1030,7 +1160,11 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, if (unlikely(ret < 0)) return ret; - return out->f_op->splice_write(pipe, out, ppos, len, flags); + splice_write = out->f_op->splice_write; + if (!splice_write) + splice_write = default_file_splice_write; + + return splice_write(pipe, out, ppos, len, flags); } /* |