fs: add ksys_getdents64() helper; remove in-kernel calls to sys_getdents64()

Using this helper allows us to avoid the in-kernel calls to the
sys_getdents64() syscall. The ksys_ prefix denotes that this function
is meant as a drop-in replacement for the syscall. In particular, it
uses the same calling convention as sys_getdents64().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index f9df17dcec1c..c056aff6d7ad 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -955,6 +955,8 @@ ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count);
 int ksys_chdir(const char __user *filename);
 int ksys_fchmod(unsigned int fd, umode_t mode);
 int ksys_fchown(unsigned int fd, uid_t user, gid_t group);
+int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
+                    unsigned int count);
 
 /*
  * The following kernel syscall equivalents are just wrappers to fs-internal