[PATCH 2/5] fallocate() on s390

Amit K. Arora
2007-04-26T18:28:12Z

This patch implements support of fallocate system call on s390(x)
platform. A wrapper is added to address the issue which s390 ABI has
with "preferred" ordering of arguments in this system call (i.e. int,
int, loff_t, loff_t).

I will request s390 experts to please review this code and verify if
this patch is correct. Thanks!

Signed-off-by: Amit Arora <aarora@in.ibm.com>
---
arch/s390/kernel/compat_wrapper.S | 10 ++++++++++
arch/s390/kernel/sys_s390.c | 10 ++++++++++
arch/s390/kernel/syscalls.S | 1 +
include/asm-s390/unistd.h | 3 ++-
4 files changed, 23 insertions(+), 1 deletion(-)

Index: linux-2.6.21/arch/s390/kernel/compat_wrapper.S
===================================================================
--- linux-2.6.21.orig/arch/s390/kernel/compat_wrapper.S
+++ linux-2.6.21/arch/s390/kernel/compat_wrapper.S
@@ -1682,3 +1682,13 @@ compat_sys_utimes_wrapper:
llgtr %r2,%r2 # char *
llgtr %r3,%r3 # struct compat_timeval *
jg compat_sys_utimes
+
+ .globl s390_fallocate_wrapper
+s390_fallocate_wrapper:
+ lgfr %r2,%r2 # int
+ sllg %r3,%r3,32 # get high word of 64bit loff_t
+ or %r3,%r4 # get low word of 64bit loff_t
+ sllg %r4,%r5,32 # get high word of 64bit loff_t
+ or %r4,%r6 # get low word of 64bit loff_t
+ llgf %r5,164(%r15) # unsigned int
+ jg s390_fallocate
Index: linux-2.6.21/arch/s390/kernel/sys_s390.c
===================================================================
--- linux-2.6.21.orig/arch/s390/kernel/sys_s390.c
+++ linux-2.6.21/arch/s390/kernel/sys_s390.c
@@ -268,6 +268,16 @@ s390_fadvise64_64(struct fadvise64_64_ar
}

/*
+ * This is a wrapper to call sys_fallocate(). Since s390 ABI has a problem
+ * with the int, int, loff_t, loff_t ordering of arguments, this wrapper
+ * is required.
+ */
+asmlinkage long s390_fallocate(int fd, loff_t offset, loff_t len, int mode)
+{
+ return sys_fallocate(fd, mode, offset, len);
+}
+
+/*
* Do a system call from kernel instead of calling sys_execve so we
* end up with proper pt_regs.
*/
Index: linux-2.6.21/arch/s390/kernel/syscalls.S
===================================================================
--- linux-2.6.21.orig/arch/s390/kernel/syscalls.S
+++ linux-2.6.21/arch/s390/kernel/syscalls.S
@@ -322,3 +322,4 @@ NI_SYSCALL /* 310 sys_move_pages *
SYSCALL(sys_getcpu,sys_getcpu,sys_getcpu_wrapper)
SYSCALL(sys_epoll_pwait,sys_epoll_pwait,compat_sys_epoll_pwait_wrapper)
SYSCALL(sys_utimes,sys_utimes,compat_sys_utimes_wrapper)
+SYSCALL(s390_fallocate,s390_fallocate,s390_fallocate_wrapper)
Index: linux-2.6.21/include/asm-s390/unistd.h
===================================================================
--- linux-2.6.21.orig/include/asm-s390/unistd.h
+++ linux-2.6.21/include/asm-s390/unistd.h
@@ -251,8 +251,9 @@
#define __NR_getcpu 311
#define __NR_epoll_pwait 312
#define __NR_utimes 313
+#define __NR_fallocate 314

-#define NR_syscalls 314
+#define NR_syscalls 315

/*
* There are some system calls that are not present on 64 bit, some