f2fs: relocate inode_{,un}lock in F2FS_IOC_SETFLAGS

This patch expands cover region of inode->i_rwsem to keep setting flag
atomically.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -1473,10 +1473,10 @@ static int f2fs_ioc_setflags(struct file *filp, unsigned long arg)
 	if (ret)
 		return ret;
 
-	flags = f2fs_mask_flags(inode->i_mode, flags);
-
 	inode_lock(inode);
 
+	flags = f2fs_mask_flags(inode->i_mode, flags);
+
 	oldflags = fi->i_flags;
 
 	if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL)) {
@@ -1490,10 +1490,11 @@ static int f2fs_ioc_setflags(struct file *filp, unsigned long arg)
 	flags = flags & FS_FL_USER_MODIFIABLE;
 	flags |= oldflags & ~FS_FL_USER_MODIFIABLE;
 	fi->i_flags = flags;
-	inode_unlock(inode);
 
 	inode->i_ctime = current_time(inode);
 	f2fs_set_inode_flags(inode);
+
+	inode_unlock(inode);
 out:
 	mnt_drop_write_file(filp);
 	return ret;