mirror_zfs/config/kernel-bio-tryget.m4
Brian Behlendorf 49f065d5a4 Linux 5.5 compat: blkg_tryget()
Commit https://github.com/torvalds/linux/commit/9e8d42a0f accidentally
converted the static inline function blkg_tryget() to GPL-only for
kernels built with CONFIG_PREEMPT_RCU=y and CONFIG_BLK_CGROUP=y.

Resolve the build issue by providing our own equivalent functionality
when needed which uses rcu_read_lock_sched() internally as before.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #9745
Closes #10072
2020-05-12 10:53:32 -07:00

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dnl #
dnl # Linux 5.5 API,
dnl #
dnl # The Linux 5.5 kernel updated percpu_ref_tryget() which is inlined by
dnl # blkg_tryget() to use rcu_read_lock() instead of rcu_read_lock_sched().
dnl # As a side effect the function was converted to GPL-only.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKG_TRYGET], [
ZFS_LINUX_TEST_SRC([blkg_tryget], [
#include <linux/blk-cgroup.h>
#include <linux/bio.h>
#include <linux/fs.h>
],[
struct blkcg_gq blkg __attribute__ ((unused));
bool rc __attribute__ ((unused));
rc = blkg_tryget(&blkg);
], [], [$ZFS_META_LICENSE])
])
AC_DEFUN([ZFS_AC_KERNEL_BLKG_TRYGET], [
AC_MSG_CHECKING([whether blkg_tryget() is available])
ZFS_LINUX_TEST_RESULT([blkg_tryget], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLKG_TRYGET, 1, [blkg_tryget() is available])
AC_MSG_CHECKING([whether blkg_tryget() is GPL-only])
ZFS_LINUX_TEST_RESULT([blkg_tryget_license], [
AC_MSG_RESULT(no)
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLKG_TRYGET_GPL_ONLY, 1,
[blkg_tryget() GPL-only])
])
],[
AC_MSG_RESULT(no)
])
])