[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, 4 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 408fe89498f4..20fa5f6d7269 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1032,6 +1032,8 @@ struct file_operations {
         int (*check_flags)(int);
         int (*dir_notify)(struct file *filp, unsigned long arg);
         int (*flock) (struct file *, int, struct file_lock *);
+        ssize_t (*splice_write)(struct inode *, struct file *, size_t, unsigned int);
+        ssize_t (*splice_read)(struct file *, struct inode *, size_t, unsigned int);
 };
 
 struct inode_operations {
@@ -1609,6 +1611,8 @@ extern ssize_t generic_file_sendfile(struct file *, loff_t *, size_t, read_actor
 extern void do_generic_mapping_read(struct address_space *mapping,
                                     struct file_ra_state *, struct file *,
                                     loff_t *, read_descriptor_t *, read_actor_t);
+extern ssize_t generic_file_splice_read(struct file *, struct inode *, size_t, unsigned int);
+extern ssize_t generic_file_splice_write(struct inode *, struct file *, size_t, unsigned int);
 extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
 extern ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,