lustre: Account for changelog_ext_rec in CR_MAXSIZE

CR_MAXSIZE needs to account for an llog_changelog_rec that actually
contains a changelog_ext_rec structure rather than a changelog_rec.
With out doing so, a file size approaching the Linux kernel NAME_MAX
length that is renamed to a size also close to, or at, NAME_MAX will
exceed CR_MAXSIZE and trip an assertion.

Signed-off-by: Christopher J. Morrone <morrone2@llnl.gov>
Reviewed-on: http://review.whamcloud.com/6993
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3587
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lustre/lustre_user.h

@@ -760,7 +760,8 @@ static inline void hsm_set_cl_error(int *flags, int error)
 	*flags |= (error << CLF_HSM_ERR_L);
 }
 
-#define CR_MAXSIZE cfs_size_round(2*NAME_MAX + 1 + sizeof(struct changelog_rec))
+#define CR_MAXSIZE cfs_size_round(2*NAME_MAX + 1 + \
+				  sizeof(struct changelog_ext_rec))
 
 struct changelog_rec {
 	__u16		 cr_namelen;