[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 <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/socket.c b/net/socket.c
index fcd77eac0ccf..b13042f68c02 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -119,6 +119,9 @@ static ssize_t sock_writev(struct file *file, const struct iovec *vector,
 static ssize_t sock_sendpage(struct file *file, struct page *page,
                              int offset, size_t size, loff_t *ppos, int more);
 
+extern ssize_t generic_splice_sendpage(struct inode *inode, struct file *out,
+                                size_t len, unsigned int flags);
+
 
 /*
  *      Socket files have a set of 'special' operations as well as the generic file ones. These don't appear
@@ -141,7 +144,8 @@ static struct file_operations socket_file_ops = {
         .fasync =       sock_fasync,
         .readv =        sock_readv,
         .writev =       sock_writev,
-        .sendpage =     sock_sendpage
+        .sendpage =     sock_sendpage,
+        .splice_write = generic_splice_sendpage,
 };
 
 /*