+# LC_CANCEL_DIRTY_PAGE
+# 2.6.20 introduse cancel_dirty_page instead of
+# clear_page_dirty.
+AC_DEFUN([LC_CANCEL_DIRTY_PAGE],
+[AC_MSG_CHECKING([kernel has cancel_dirty_page])
+LB_LINUX_TRY_COMPILE([
+ #include <linux/page-flags.h>
+],[
+ cancel_dirty_page(NULL, 0);
+],[
+ AC_MSG_RESULT(yes)
+ AC_DEFINE(HAVE_CANCEL_DIRTY_PAGE, 1,
+ [kernel has cancel_dirty_page instead of clear_page_dirty])
+],[
+ AC_MSG_RESULT(NO)
+])
+])
+
+#
+# LC_PAGE_CONSTANT
+#
+# In order to support raid5 zerocopy patch, we have to patch the kernel to make
+# it support constant page, which means the page won't be modified during the
+# IO.
+#
+AC_DEFUN([LC_PAGE_CONSTANT],
+[AC_MSG_CHECKING([if kernel have PageConstant defined])
+LB_LINUX_TRY_COMPILE([
+ #include <linux/page-flags.h>
+],[
+ #ifndef PG_constant
+ #error "Have no raid5 zcopy patch"
+ #endif
+],[
+ AC_MSG_RESULT(yes)
+ AC_DEFINE(HAVE_PAGE_CONSTANT, 1, [kernel have PageConstant supported])
+],[
+ AC_MSG_RESULT(no);
+])
+])
+
+# RHEL5 in FS-cache patch rename PG_checked flag
+# into PG_fs_misc
+AC_DEFUN([LC_PG_FS_MISC],
+[AC_MSG_CHECKING([kernel has PG_fs_misc])
+LB_LINUX_TRY_COMPILE([
+ #include <linux/page-flags.h>
+],[
+ #ifndef PG_fs_misc
+ #error PG_fs_misc not defined in kernel
+ #endif
+],[
+ AC_MSG_RESULT(yes)
+ AC_DEFINE(HAVE_PG_FS_MISC, 1,
+ [is kernel have PG_fs_misc])
+],[
+ AC_MSG_RESULT(NO)
+])
+])
+
+AC_DEFUN([LC_EXPORT_TRUNCATE_COMPLETE],
+[LB_CHECK_SYMBOL_EXPORT([truncate_complete_page],
+[mm/truncate.c],[
+AC_DEFINE(HAVE_TRUNCATE_COMPLETE_PAGE, 1,
+ [kernel export truncate_complete_page])
+],[
+])
+])
+
+AC_DEFUN([LC_EXPORT_D_REHASH_COND],
+[LB_CHECK_SYMBOL_EXPORT([d_rehash_cond],
+[fs/dcache.c],[
+AC_DEFINE(HAVE_D_REHASH_COND, 1,
+ [d_rehash_cond is exported by the kernel])
+],[
+])
+])
+
+AC_DEFUN([LC_EXPORT___D_REHASH],
+[LB_CHECK_SYMBOL_EXPORT([__d_rehash],
+[fs/dcache.c],[
+AC_DEFINE(HAVE___D_REHASH, 1,
+ [__d_rehash is exported by the kernel])
+],[
+])
+])
+
+# The actual symbol exported varies among architectures, so we need
+# to check many symbols (but only in the current architecture.) No
+# matter what symbol is exported, the kernel #defines node_to_cpumask
+# to the appropriate function and that's what we use.
+AC_DEFUN([LC_EXPORT_NODE_TO_CPUMASK],
+ [LB_LINUX_ARCH
+ LB_CHECK_SYMBOL_EXPORT([node_to_cpumask],
+ [arch/$LINUX_ARCH/mm/numa.c],
+ [AC_DEFINE(HAVE_NODE_TO_CPUMASK, 1,
+ [node_to_cpumask is exported by
+ the kernel])]) # x86_64
+ LB_CHECK_SYMBOL_EXPORT([node_to_cpu_mask],
+ [arch/$LINUX_ARCH/kernel/smpboot.c],
+ [AC_DEFINE(HAVE_NODE_TO_CPUMASK, 1,
+ [node_to_cpumask is exported by
+ the kernel])]) # ia64
+ LB_CHECK_SYMBOL_EXPORT([node_2_cpu_mask],
+ [arch/$LINUX_ARCH/kernel/smpboot.c],
+ [AC_DEFINE(HAVE_NODE_TO_CPUMASK, 1,
+ [node_to_cpumask is exported by
+ the kernel])]) # i386
+ ])
+
+#
+# LC_VFS_INTENT_PATCHES
+#
+# check if the kernel has the VFS intent patches
+AC_DEFUN([LC_VFS_INTENT_PATCHES],
+[AC_MSG_CHECKING([if the kernel has the VFS intent patches])
+LB_LINUX_TRY_COMPILE([
+ #include <linux/fs.h>
+ #include <linux/namei.h>
+],[
+ struct nameidata nd;
+ struct lookup_intent *it;
+
+ it = &nd.intent;
+ intent_init(it, IT_OPEN);
+ it->d.lustre.it_disposition = 0;
+ it->d.lustre.it_data = NULL;
+],[
+ AC_MSG_RESULT([yes])
+ AC_DEFINE(HAVE_VFS_INTENT_PATCHES, 1, [VFS intent patches are applied])
+],[
+ AC_MSG_RESULT([no])
+])
+])