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dnl #
dnl # 3.1 API change
dnl # The super_block structure now stores a per-filesystem shrinker.
dnl # This interface is preferable because it can be used to specifically
dnl # target only the zfs filesystem for pruning.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SHRINK], [
AC_MSG_CHECKING([whether super_block has s_shrink])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
int shrink(struct shrinker *s, struct shrink_control *sc)
{ return 0; }
static const struct super_block
sb __attribute__ ((unused)) = {
.s_shrink.shrink = shrink,
.s_shrink.seeks = DEFAULT_SEEKS,
.s_shrink.batch = 0,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_SHRINK, 1, [struct super_block has s_shrink])
],[
AC_MSG_RESULT(no)
])
])
dnl #
dnl # 3.3 API change
dnl # The super_block structure was changed to use an hlist_node instead
dnl # of a list_head for the .s_instance linkage.
dnl #
dnl # This was done in part to resolve a race in the iterate_supers_type()
dnl # function which was introduced in Linux 3.0 kernel. The iterator
dnl # was supposed to provide a safe way to call an arbitrary function on
dnl # all super blocks of a specific type. Unfortunately, because a
dnl # list_head was used it was possible for iterate_supers_type() to
dnl # get stuck spinning a super block which was just deactivated.
dnl #
dnl # This can occur because when the list head is removed from the
dnl # fs_supers list it is reinitialized to point to itself. If the
dnl # iterate_supers_type() function happened to be processing the
dnl # removed list_head it will get stuck spinning on that list_head.
dnl #
dnl # To resolve the issue for existing 3.0 - 3.2 kernels we detect when
dnl # a list_head is used. Then to prevent the spinning from occurring
dnl # the .next pointer is set to the fs_supers list_head which ensures
dnl # the iterate_supers_type() function will always terminate.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_S_INSTANCES_LIST_HEAD], [
AC_MSG_CHECKING([whether super_block has s_instances list_head])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
],[
struct super_block sb __attribute__ ((unused));
INIT_LIST_HEAD(&sb.s_instances);
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_S_INSTANCES_LIST_HEAD, 1,
[struct super_block has s_instances list_head])
],[
AC_MSG_RESULT(no)
])
])
AC_DEFUN([ZFS_AC_KERNEL_NR_CACHED_OBJECTS], [
AC_MSG_CHECKING([whether sops->nr_cached_objects() exists])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
int nr_cached_objects(struct super_block *sb) { return 0; }
static const struct super_operations
sops __attribute__ ((unused)) = {
.nr_cached_objects = nr_cached_objects,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_NR_CACHED_OBJECTS, 1,
[sops->nr_cached_objects() exists])
],[
AC_MSG_RESULT(no)
])
])
AC_DEFUN([ZFS_AC_KERNEL_FREE_CACHED_OBJECTS], [
AC_MSG_CHECKING([whether sops->free_cached_objects() exists])
ZFS_LINUX_TRY_COMPILE([
#include <linux/fs.h>
void free_cached_objects(struct super_block *sb, int x)
{ return; }
static const struct super_operations
sops __attribute__ ((unused)) = {
.free_cached_objects = free_cached_objects,
};
],[
],[
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_FREE_CACHED_OBJECTS, 1,
[sops->free_cached_objects() exists])
],[
AC_MSG_RESULT(no)
])
])
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