freebsd-dev/config/kernel-follow-link-nameidata.m4
Brian Behlendorf bd29109f1a Linux 4.2 compat: follow_link() / put_link()
As of Linux 4.2 the kernel has completely retired the nameidata
structure.  One of the few remaining consumers of this interface
were the follow_link() and put_link() callbacks.

This patch adds the required checks to configure to detect the
interface change and updates the functions accordingly.  Migrating
to the simple_follow_link() interface was considered but was decided
against ironically due to the increased complexity.

It also should be noted that the kernel follow_link() and put_link()
interfaces changes several times after 4.1 and but before 4.2.  This
means there is a narrow range of kernel commits which never appear
in an official tag of the Linux kernel which ZoL will not build.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Issue #3596
2015-07-17 09:18:16 -07:00

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dnl #
dnl # 4.2 API change
dnl # This kernel retired the nameidata structure which forced the
dnl # restructuring of the follow_link() prototype and how it is called.
dnl # We check for the new interface rather than detecting the old one.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_FOLLOW_LINK], [
AC_MSG_CHECKING([whether iops->follow_link() passes nameidata])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
const char *follow_link(struct dentry *de, void **cookie)
{ return "symlink"; }
static struct inode_operations iops __attribute__ ((unused)) = {
.follow_link = follow_link,
};
],[
],[
AC_MSG_RESULT(no)
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_FOLLOW_LINK_NAMEIDATA, 1,
[iops->follow_link() nameidata])
])
])