cifs: add cifs_revalidate_file

...to allow updating inode attributes on an existing inode by
filehandle. Change mmap and llseek codepaths to use that
instead of cifs_revalidate_dentry since they have a filehandle
readily available.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index ce9199f..39e47f4 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -104,10 +104,12 @@
 extern struct inode *cifs_iget(struct super_block *sb,
 			       struct cifs_fattr *fattr);
 
+extern int cifs_get_file_info(struct file *filp);
 extern int cifs_get_inode_info(struct inode **pinode,
 			const unsigned char *search_path,
 			FILE_ALL_INFO *pfile_info,
 			struct super_block *sb, int xid, const __u16 *pfid);
+extern int cifs_get_file_info_unix(struct file *filp);
 extern int cifs_get_inode_info_unix(struct inode **pinode,
 			const unsigned char *search_path,
 			struct super_block *sb, int xid);