[PATCH v4 5/6] namei: add getname_uflags()

[Dmitry Kadashev <dkadashev@gmail.com>]

There are a couple of places where we already open-code the (flags &
AT_EMPTY_PATH) check and io_uring will likely add another one in the
future.  Let's just add a simple helper getname_uflags() that handles
this directly and use it.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/io-uring/20210415100815.edrn4a7cy26wkowe@wittgenstein/
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
---

Christian, I've kept your Signed-off-by here, even though I took only
part of the change (leaving getname_flags() switch to boolean out to
keep the change smaller). Please let me know if that is OK or not and/or
if you prefer the rest of the change be restored.

 fs/exec.c          | 8 ++------
 fs/namei.c         | 8 ++++++++
 include/linux/fs.h | 1 +
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 18594f11c31f..df33ecaf2111 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -2069,10 +2069,8 @@ SYSCALL_DEFINE5(execveat,
 		const char __user *const __user *, envp,
 		int, flags)
 {
-	int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
-
 	return do_execveat(fd,
-			   getname_flags(filename, lookup_flags, NULL),
+			   getname_uflags(filename, flags),
 			   argv, envp, flags);
 }
 
@@ -2090,10 +2088,8 @@ COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
 		       const compat_uptr_t __user *, envp,
 		       int,  flags)
 {
-	int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
-
 	return compat_do_execveat(fd,
-				  getname_flags(filename, lookup_flags, NULL),
+				  getname_uflags(filename, flags),
 				  argv, envp, flags);
 }
 #endif
diff --git a/fs/namei.c b/fs/namei.c
index 76572d703e82..010455938826 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -203,6 +203,14 @@ getname_flags(const char __user *filename, int flags, int *empty)
 	return result;
 }
 
+struct filename *
+getname_uflags(const char __user *filename, int uflags)
+{
+	int flags = (uflags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
+
+	return getname_flags(filename, flags, NULL);
+}
+
 struct filename *
 getname(const char __user * filename)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bf4e90d3ab18..c46e70682fc0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2783,6 +2783,7 @@ static inline struct file *file_clone_open(struct file *file)
 extern int filp_close(struct file *, fl_owner_t id);
 
 extern struct filename *getname_flags(const char __user *, int, int *);
+extern struct filename *getname_uflags(const char __user *, int);
 extern struct filename *getname(const char __user *);
 extern struct filename *getname_kernel(const char *);
 extern void putname(struct filename *name);
-- 
2.30.2