[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>
diff --git a/include/asm-i386/unistd.h b/include/asm-i386/unistd.h
index 014e356..789e9bd 100644
--- a/include/asm-i386/unistd.h
+++ b/include/asm-i386/unistd.h
@@ -318,8 +318,9 @@
#define __NR_unshare 310
#define __NR_set_robust_list 311
#define __NR_get_robust_list 312
+#define __NR_sys_splice 313
-#define NR_syscalls 313
+#define NR_syscalls 314
/*
* user-visible error numbers are in the range -1 - -128: see
diff --git a/include/asm-ia64/unistd.h b/include/asm-ia64/unistd.h
index 019956c..36070c1 100644
--- a/include/asm-ia64/unistd.h
+++ b/include/asm-ia64/unistd.h
@@ -285,12 +285,13 @@
#define __NR_faccessat 1293
/* 1294, 1295 reserved for pselect/ppoll */
#define __NR_unshare 1296
+#define __NR_splice 1297
#ifdef __KERNEL__
#include <linux/config.h>
-#define NR_syscalls 273 /* length of syscall table */
+#define NR_syscalls 274 /* length of syscall table */
#define __ARCH_WANT_SYS_RT_SIGACTION
diff --git a/include/asm-powerpc/unistd.h b/include/asm-powerpc/unistd.h
index 1e99074..536ba08 100644
--- a/include/asm-powerpc/unistd.h
+++ b/include/asm-powerpc/unistd.h
@@ -301,8 +301,9 @@
#define __NR_pselect6 280
#define __NR_ppoll 281
#define __NR_unshare 282
+#define __NR_splice 283
-#define __NR_syscalls 283
+#define __NR_syscalls 284
#ifdef __KERNEL__
#define __NR__exit __NR_exit
diff --git a/include/asm-x86_64/unistd.h b/include/asm-x86_64/unistd.h
index fcc5163..f21ff2c 100644
--- a/include/asm-x86_64/unistd.h
+++ b/include/asm-x86_64/unistd.h
@@ -609,8 +609,10 @@
__SYSCALL(__NR_set_robust_list, sys_set_robust_list)
#define __NR_get_robust_list 274
__SYSCALL(__NR_get_robust_list, sys_get_robust_list)
+#define __NR_splice 275
+__SYSCALL(__NR_splice, sys_splice)
-#define __NR_syscall_max __NR_get_robust_list
+#define __NR_syscall_max __NR_splice
#ifndef __NO_STUBS
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 408fe89..20fa5f6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1032,6 +1032,8 @@
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 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,
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index e487e3b..e78ffc7 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -569,5 +569,7 @@
asmlinkage long compat_sys_openat(unsigned int dfd, const char __user *filename,
int flags, int mode);
asmlinkage long sys_unshare(unsigned long unshare_flags);
+asmlinkage long sys_splice(int fdin, int fdout, size_t len,
+ unsigned int flags);
#endif