[PATCH] s390: fadvise hint values.

Add special case for the POSIX_FADV_DONTNEED and POSIX_FADV_NOREUSE hint
values for s390-64.  The user space values in the s390-64 glibc headers for
these two defines have always been 6 and 7 instead of 4 and 5.  All 64 bit
applications therefore use the "wrong" values.  To get these applications
working without recompiling the kernel needs to accept the "wrong" values.
Since the values for s390-31 are 4 and 5 the compat wrapper for fadvise64
and fadvise64_64 need to rewrite the values for 31 bit system calls.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 50 insertions, 2 deletions

diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 6140562..18610ce 100644
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -58,6 +58,7 @@
 #include <linux/compat.h>
 #include <linux/vfs.h>
 #include <linux/ptrace.h>
+#include <linux/fadvise.h>
 
 #include <asm/types.h>
 #include <asm/ipc.h>
@@ -1043,3 +1044,40 @@ sys32_timer_create(clockid_t which_clock, struct compat_sigevent *se32,
 
 	return ret;
 }
+
+/*
+ * 31 bit emulation wrapper functions for sys_fadvise64/fadvise64_64.
+ * These need to rewrite the advise values for POSIX_FADV_{DONTNEED,NOREUSE}
+ * because the 31 bit values differ from the 64 bit values.
+ */
+
+asmlinkage long
+sys32_fadvise64(int fd, loff_t offset, size_t len, int advise)
+{
+	if (advise == 4)
+		advise = POSIX_FADV_DONTNEED;
+	else if (advise == 5)
+		advise = POSIX_FADV_NOREUSE;
+	return sys_fadvise64(fd, offset, len, advise);
+}
+
+struct fadvise64_64_args {
+	int fd;
+	long long offset;
+	long long len;
+	int advice;
+};
+
+asmlinkage long
+sys32_fadvise64_64(struct fadvise64_64_args __user *args)
+{
+	struct fadvise64_64_args a;
+
+	if ( copy_from_user(&a, args, sizeof(a)) )
+		return -EFAULT;
+	if (a.advice == 4)
+		a.advice = POSIX_FADV_DONTNEED;
+	else if (a.advice == 5)
+		a.advice = POSIX_FADV_NOREUSE;
+	return sys_fadvise64_64(a.fd, a.offset, a.len, a.advice);
+}
diff --git a/arch/s390/kernel/compat_wrapper.S b/arch/s390/kernel/compat_wrapper.S
index bf52973..799a98e 100644
--- a/arch/s390/kernel/compat_wrapper.S
+++ b/arch/s390/kernel/compat_wrapper.S
@@ -1251,12 +1251,12 @@ sys32_fadvise64_wrapper:
 	or	%r3,%r4			# get low word of 64bit loff_t
 	llgfr	%r4,%r5			# size_t (unsigned long)
 	lgfr	%r5,%r6			# int
-	jg	sys_fadvise64
+	jg	sys32_fadvise64
 
 	.globl	sys32_fadvise64_64_wrapper
 sys32_fadvise64_64_wrapper:
 	llgtr	%r2,%r2			# struct fadvise64_64_args *
-	jg	s390_fadvise64_64
+	jg	sys32_fadvise64_64
 
 	.globl	sys32_clock_settime_wrapper
 sys32_clock_settime_wrapper:
diff --git a/include/linux/fadvise.h b/include/linux/fadvise.h
index 6fc656d..e8e7471 100644
--- a/include/linux/fadvise.h
+++ b/include/linux/fadvise.h
@@ -5,7 +5,17 @@
 #define POSIX_FADV_RANDOM	1 /* Expect random page references.  */
 #define POSIX_FADV_SEQUENTIAL	2 /* Expect sequential page references.  */
 #define POSIX_FADV_WILLNEED	3 /* Will need these pages.  */
+
+/*
+ * The advise values for POSIX_FADV_DONTNEED and POSIX_ADV_NOREUSE
+ * for s390-64 differ from the values for the rest of the world.
+ */
+#if defined(__s390x__)
+#define POSIX_FADV_DONTNEED	6 /* Don't need these pages.  */
+#define POSIX_FADV_NOREUSE	7 /* Data will be accessed once.  */
+#else
 #define POSIX_FADV_DONTNEED	4 /* Don't need these pages.  */
 #define POSIX_FADV_NOREUSE	5 /* Data will be accessed once.  */
+#endif
 
 #endif	/* FADVISE_H_INCLUDED */