CRED: Wrap task credential accesses in the UDF filesystem

Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.

Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().

Change some task->e?[ug]id to task_e?[ug]id().  In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: James Morris <jmorris@namei.org>

fs/udf/ialloc.c

@@ -126,13 +126,13 @@ struct inode *udf_new_inode(struct inode *dir, int mode, int *err)
 	}
 	mutex_unlock(&sbi->s_alloc_mutex);
 	inode->i_mode = mode;
-	inode->i_uid = current->fsuid;
+	inode->i_uid = current_fsuid();
 	if (dir->i_mode & S_ISGID) {
 		inode->i_gid = dir->i_gid;
 		if (S_ISDIR(mode))
 			mode |= S_ISGID;
 	} else {
-		inode->i_gid = current->fsgid;
+		inode->i_gid = current_fsgid();
 	}
 
 	iinfo->i_location.logicalBlockNum = block;

fs/udf/namei.c

@@ -604,7 +604,7 @@ static int udf_mknod(struct inode *dir, struct dentry *dentry, int mode,
 		goto out;
 
 	iinfo = UDF_I(inode);
-	inode->i_uid = current->fsuid;
+	inode->i_uid = current_fsuid();
 	init_special_inode(inode, mode, rdev);
 	fi = udf_add_entry(dir, dentry, &fibh, &cfi, &err);
 	if (!fi) {