From 5274f052e7b3dbd81935772eb551dfd0325dfa9d Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 30 Mar 2006 15:15:30 +0200 Subject: [PATCH] Introduce sys_splice() system call This adds support for the sys_splice system call. Using a pipe as a transport, it can connect to files or sockets (latter as output only). From the splice.c comments: "splice": joining two ropes together by interweaving their strands. This is the "extended pipe" functionality, where a pipe is used as an arbitrary in-memory buffer. Think of a pipe as a small kernel buffer that you can use to transfer data from one end to the other. The traditional unix read/write is extended with a "splice()" operation that transfers data buffers to or from a pipe buffer. Named by Larry McVoy, original implementation from Linus, extended by Jens to support splicing to files and fixing the initial implementation bugs. Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds --- fs/pipe.c | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) (limited to 'fs/pipe.c') diff --git a/fs/pipe.c b/fs/pipe.c index e2f4f1d9ffc..2414bf270db 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -94,11 +95,20 @@ static void anon_pipe_buf_release(struct pipe_inode_info *info, struct pipe_buff { struct page *page = buf->page; - if (info->tmp_page) { - __free_page(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 + */ + if (page_count(page) == 1 && !info->tmp_page) { + info->tmp_page = page; return; } - info->tmp_page = page; + + /* + * Otherwise just release our reference to it + */ + page_cache_release(page); } static void *anon_pipe_buf_map(struct file *file, struct pipe_inode_info *info, struct pipe_buffer *buf) @@ -152,6 +162,11 @@ pipe_readv(struct file *filp, const struct iovec *_iov, chars = total_len; addr = ops->map(filp, info, buf); + if (IS_ERR(addr)) { + if (!ret) + ret = PTR_ERR(addr); + break; + } error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars); ops->unmap(info, buf); if (unlikely(error)) { @@ -254,8 +269,16 @@ pipe_writev(struct file *filp, const struct iovec *_iov, 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); + void *addr; + int error; + + addr = ops->map(filp, info, buf); + if (IS_ERR(addr)) { + error = PTR_ERR(addr); + goto out; + } + error = pipe_iov_copy_from_user(offset + addr, iov, + chars); ops->unmap(info, buf); ret = error; do_wakeup = 1; -- cgit v1.2.3-18-g5258