[PATCH 04/10] Introduce vfs_fcntl() helper

[ntl@pobox.com]

From: Nathan Lynch <ntl@pobox.com>

When restoring process state from a checkpoint image, it will be
necessary to restore file status flags; add vfs_fcntl() for this
purpose.

Based on original code by Oren Laadan.

Signed-off-by: Oren Laadan <orenl@cs.columbia.edu>
[ntl: extracted from "c/r: checkpoint and restart open file descriptors"]
Signed-off-by: Nathan Lynch <ntl@pobox.com>
---
 fs/fcntl.c         |   21 +++++++++++++--------
 include/linux/fs.h |    2 ++
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/fs/fcntl.c b/fs/fcntl.c
index ecc8b39..8e797b7 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -426,6 +426,18 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 	return err;
 }
 
+int vfs_fcntl(int fd, unsigned int cmd, unsigned long arg, struct file *filp)
+{
+	int err;
+
+	err = security_file_fcntl(filp, cmd, arg);
+	if (err)
+		goto out;
+	err = do_fcntl(fd, cmd, arg, filp);
+ out:
+	return err;
+}
+
 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 {	
 	struct file *filp;
@@ -435,14 +447,7 @@ SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 	if (!filp)
 		goto out;
 
-	err = security_file_fcntl(filp, cmd, arg);
-	if (err) {
-		fput(filp);
-		return err;
-	}
-
-	err = do_fcntl(fd, cmd, arg, filp);
-
+	err = vfs_fcntl(fd, cmd, arg, filp);
  	fput(filp);
 out:
 	return err;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 315ded4..175bb75 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1112,6 +1112,8 @@ struct file_lock {
 
 #include <linux/fcntl.h>
 
+extern int vfs_fcntl(int fd, unsigned cmd, unsigned long arg, struct file *fp);
+
 extern void send_sigio(struct fown_struct *fown, int fd, int band);
 
 #ifdef CONFIG_FILE_LOCKING
-- 
1.7.4