CRED: Use creds in file structs

Attach creds to file structs and discard f_uid/f_gid.

file_operations::open() methods (such as hppfs_open()) should use file->f_cred
rather than current_cred().  At the moment file->f_cred will be current_cred()
at this point.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/fs/hppfs/hppfs.c b/fs/hppfs/hppfs.c
index 795e2c1..b278f7f 100644
--- a/fs/hppfs/hppfs.c
+++ b/fs/hppfs/hppfs.c
@@ -426,7 +426,7 @@
 
 static int hppfs_open(struct inode *inode, struct file *file)
 {
-	const struct cred *cred = current_cred();
+	const struct cred *cred = file->f_cred;
 	struct hppfs_private *data;
 	struct vfsmount *proc_mnt;
 	struct dentry *proc_dentry;
@@ -490,7 +490,7 @@
 
 static int hppfs_dir_open(struct inode *inode, struct file *file)
 {
-	const struct cred *cred = current_cred();
+	const struct cred *cred = file->f_cred;
 	struct hppfs_private *data;
 	struct vfsmount *proc_mnt;
 	struct dentry *proc_dentry;