[PATCH] Add support for the sys_vmsplice syscall

sys_splice() moves data to/from pipes with a file input/output. sys_vmsplice()
moves data to a pipe, with the input being a user address range instead.

This uses an approach suggested by Linus, where we can hold partial ranges
inside the pages[] map. Hopefully this will be useful for network
receive support as well.

Signed-off-by: Jens Axboe <axboe@suse.de>

include/asm-i386/unistd.h

@@ -321,8 +321,9 @@
 #define __NR_splice		313
 #define __NR_sync_file_range	314
 #define __NR_tee		315
+#define __NR_vmsplice		316
 
-#define NR_syscalls 316
+#define NR_syscalls 317
 
 /*
  * user-visible error numbers are in the range -1 - -128: see

include/asm-ia64/unistd.h

@@ -290,12 +290,13 @@
 #define __NR_get_robust_list		1299
 #define __NR_sync_file_range		1300
 #define __NR_tee			1301
+#define __NR_vmsplice			1302
 
 #ifdef __KERNEL__
 
 #include <linux/config.h>
 
-#define NR_syscalls			278 /* length of syscall table */
+#define NR_syscalls			279 /* length of syscall table */
 
 #define __ARCH_WANT_SYS_RT_SIGACTION
 

include/asm-powerpc/unistd.h

@@ -303,8 +303,9 @@
 #define __NR_unshare		282
 #define __NR_splice		283
 #define __NR_tee		284
+#define __NR_vmsplice		285
 
-#define __NR_syscalls		285
+#define __NR_syscalls		286
 
 #ifdef __KERNEL__
 #define __NR__exit __NR_exit

include/asm-x86_64/unistd.h

@@ -615,8 +615,10 @@ __SYSCALL(__NR_splice, sys_splice)
 __SYSCALL(__NR_tee, sys_tee)
 #define __NR_sync_file_range	277
 __SYSCALL(__NR_sync_file_range, sys_sync_file_range)
+#define __NR_vmsplice		278
+__SYSCALL(__NR_vmsplice, sys_vmsplice)
 
-#define __NR_syscall_max __NR_sync_file_range
+#define __NR_syscall_max __NR_vmsplice
 
 #ifndef __NO_STUBS
 

include/linux/syscalls.h

@@ -574,6 +574,9 @@ asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
 			   int fd_out, loff_t __user *off_out,
 			   size_t len, unsigned int flags);
 
+asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
+			     unsigned long nr_segs, unsigned int flags);
+
 asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags);
 
 asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,