[PATCH 058/109] fs: add do_compat_fcntl64() helper; remove in-kernel call to compat syscall

From: Dominik Brodowski
Date: Thu Mar 29 2018 - 07:50:45 EST


Using the fs-internal do_compat_fcntl64() helper allows us to get rid of
the fs-internal call to the compat_sys_fcntl64() syscall.

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@xxxxxxxxxxxxxxxxxxxxxxxxxx

Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
---
fs/fcntl.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 1e97f1fda90c..d737ff082472 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -607,8 +607,8 @@ static int fixup_compat_flock(struct flock *flock)
return 0;
}

-COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
- compat_ulong_t, arg)
+static long do_compat_fcntl64(unsigned int fd, unsigned int cmd,
+ compat_ulong_t arg)
{
struct fd f = fdget_raw(fd);
struct flock flock;
@@ -672,6 +672,12 @@ COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
return err;
}

+COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
+ compat_ulong_t, arg)
+{
+ return do_compat_fcntl64(fd, cmd, arg);
+}
+
COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,
compat_ulong_t, arg)
{
@@ -684,7 +690,7 @@ COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,
case F_OFD_SETLKW:
return -EINVAL;
}
- return compat_sys_fcntl64(fd, cmd, arg);
+ return do_compat_fcntl64(fd, cmd, arg);
}
#endif

--
2.16.3