CRED: Wrap task credential accesses in the CIFS 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>
Cc: Steve French <sfrench@samba.org>
Cc: linux-cifs-client@lists.samba.org
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/fs/cifs/cifs_fs_sb.h b/fs/cifs/cifs_fs_sb.h
index 877c854..1e7b874 100644
--- a/fs/cifs/cifs_fs_sb.h
+++ b/fs/cifs/cifs_fs_sb.h
@@ -19,7 +19,7 @@
 #define _CIFS_FS_SB_H
 
 #define CIFS_MOUNT_NO_PERM      1 /* do not do client vfs_perm check */
-#define CIFS_MOUNT_SET_UID      2 /* set current->euid in create etc. */
+#define CIFS_MOUNT_SET_UID      2 /* set current's euid in create etc. */
 #define CIFS_MOUNT_SERVER_INUM  4 /* inode numbers from uniqueid from server */
 #define CIFS_MOUNT_DIRECT_IO    8 /* do not write nor read through page cache */
 #define CIFS_MOUNT_NO_XATTR     0x10  /* if set - disable xattr support       */