[#LU-10371] Kernel >= 4.8 has no posix_acl_xattr_entry a

Compiling on Kernel >= 4.8 results in error

error: ‘struct posix_acl_xattr_header’ has no member named ‘a_entries’

due to Linux Kernel commit 2211d5ba5c6c4e972ba6dbc912b2897425ea6621

...
-typedef struct {
+struct posix_acl_xattr_header {
        __le32                  a_version;
-       posix_acl_xattr_entry   a_entries[0];
-} posix_acl_xattr_header;
+};
...

where the a_entries[0] was removed. There exists in already a check for this structure

#
# LC_STRUCT_POSIX_ACL_XATTR
#
# Kernel version 4.8 commit 2211d5ba5c6c4e972ba6dbc912b2897425ea6621
# posix_acl: xattr representation cleanups
#
AC_DEFUN([LC_STRUCT_POSIX_ACL_XATTR], [
LB_CHECK_COMPILE([if 'struct posix_acl_xattr_{header,entry}' defined],
struct_posix_acl_xattr, [
        #include <linux/fs.h>
        #include <linux/posix_acl_xattr.h>
],[
        struct posix_acl_xattr_header *h = NULL;
        struct posix_acl_xattr_entry  *e;
        e = (void *)(h + 1);
],[
        AC_DEFINE(HAVE_STRUCT_POSIX_ACL_XATTR, 1,
                [struct posix_acl_xattr_{header,entry} defined])
])
]) # LC_STRUCT_POSIX_ACL_XATTR

so let's use the check for fixing it e.g. as follows:

diff --git a/lustre/ptlrpc/wiretest.c b/lustre/ptlrpc/wiretest.c
index 40e3d55..01a5220 100644
--- a/lustre/ptlrpc/wiretest.c
+++ b/lustre/ptlrpc/wiretest.c
@@ -4548,10 +4548,12 @@ void lustre_assert_wire_constants(void)
                 (long long)(int)offsetof(posix_acl_xattr_header, a_version));
        LASSERTF((int)sizeof(((posix_acl_xattr_header *)0)->a_version) == 4, "found %lld\n",
                 (long long)(int)sizeof(((posix_acl_xattr_header *)0)->a_version));
+#ifndef HAVE_STRUCT_POSIX_ACL_XATTR
        LASSERTF((int)offsetof(posix_acl_xattr_header, a_entries) == 4, "found %lld\n",
                 (long long)(int)offsetof(posix_acl_xattr_header, a_entries));
        LASSERTF((int)sizeof(((posix_acl_xattr_header *)0)->a_entries) == 0, "found %lld\n",
                 (long long)(int)sizeof(((posix_acl_xattr_header *)0)->a_entries));
+#endif /* HAVE_STRUCT_POSIX_ACL_XATTR */
 #endif /* CONFIG_FS_POSIX_ACL */

[LU-10371] Kernel >= 4.8 has no posix_acl_xattr_entry a_entries[0] Created: 12/Dec/17 Updated: 08/Jan/18 Resolved: 22/Dec/17
Status:	Resolved
Project:	Lustre
Component/s:	None
Affects Version/s:	Lustre 2.10.1
Fix Version/s:	Lustre 2.11.0, Lustre 2.10.3

[LU-10371] Kernel >= 4.8 has no posix_acl_xattr_entry a_entries[0] Created: 12/Dec/17 Updated: 08/Jan/18 Resolved: 22/Dec/17