fs: add ksys_open() wrapper; remove in-kernel calls to sys_open()
Using this wrapper allows us to avoid the in-kernel calls to the
sys_open() 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_open().
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: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 38805f3..f9df17d 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1057,4 +1057,15 @@ static inline int ksys_close(unsigned int fd)
return __close_fd(current->files, fd);
}
+extern long do_sys_open(int dfd, const char __user *filename, int flags,
+ umode_t mode);
+
+static inline long ksys_open(const char __user *filename, int flags,
+ umode_t mode)
+{
+ if (force_o_largefile())
+ flags |= O_LARGEFILE;
+ return do_sys_open(AT_FDCWD, filename, flags, mode);
+}
+
#endif