staging/lustre/obdclass: Proper swabbing of llog_rec_tail.

A variable-length structure preceeds llog_rec_tail within an llog
block. Thus cr_tail shouldn't be accessed directly as a structure
member but its actual location should be computed dynamically.
Signed-off-by: Henri Doreau <henri.doreau@cea.fr>
Reviewed-on: http://review.whamcloud.com/11937
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5631Reviewed-by: jacques-Charles Lafoucriere <jacques-charles.lafoucriere@cea.fr>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/obdclass/llog_swab.c

@@ -168,7 +168,8 @@ void lustre_swab_llog_rec(struct llog_rec_hdr *rec)
 	}
 	case CHANGELOG_REC:
 	{
-		struct llog_changelog_rec *cr = (struct llog_changelog_rec *)rec;
+		struct llog_changelog_rec *cr =
+			(struct llog_changelog_rec *)rec;
 
 		__swab16s(&cr->cr.cr_namelen);
 		__swab16s(&cr->cr.cr_flags);
@@ -188,6 +189,8 @@ void lustre_swab_llog_rec(struct llog_rec_hdr *rec)
 		} else {
 			tail = &cr->cr_tail;
 		}
+		tail = (struct llog_rec_tail *)((char *)tail +
+						cr->cr.cr_namelen);
 		break;
 	}
 	case CHANGELOG_USER_REC: