Fix build failures on PaX/GRSecurity patched kernels

Gentoo Hardened kernels include the PaX/GRSecurity patches. They use a
dialect of C that relies on a GCC plugin. In particular, struct
file_operations has been marked do_const in the PaX/GRSecurity dialect,
which causes GCC to consider all instances of it as const. This caused
failures in the autotools checks and the ZFS source code.

To address this, we modify the autotools checks to take into account
differences between the PaX C dialect and the regular C dialect. We also
modify struct zfs_acl's z_ops member to be a pointer to a function
pointer table. Lastly, we modify zpl_put_link() to address a PaX change
to the function prototype of nd_get_link().  This avoids compiler errors
in the PaX/GRSecurity dialect.

Note that the change in zpl_put_link() causes a warning that becomes a
build failure when debugging is enabled. Fixing that warning requires
ryao/spl@5ca50ef459c59bc74b7a7cd3af7311da2b1cd2c3.

Signed-off-by: Richard Yao <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #484

3 files changed, 85 insertions, 4 deletions

diff --git a/config/kernel-evict-inode.m4 b/config/kernel-evict-inode.m4
index 0700792f9..683cedb6d 100644
--- a/config/kernel-evict-inode.m4
+++ b/config/kernel-evict-inode.m4
@@ -7,12 +7,12 @@ AC_DEFUN([ZFS_AC_KERNEL_EVICT_INODE], [
 	AC_MSG_CHECKING([whether sops->evict_inode() exists])
 	ZFS_LINUX_TRY_COMPILE([
 		#include <linux/fs.h>
-	],[
-		void (*evict_inode) (struct inode *) = NULL;
-		struct super_operations sops __attribute__ ((unused)) = {
+		void evict_inode (struct inode * t) { return; }
+		static struct super_operations sops __attribute__ ((unused)) = {
 			.evict_inode = evict_inode,
 		};
 	],[
+	],[
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_EVICT_INODE, 1, [sops->evict_inode() exists])
 	],[
diff --git a/config/kernel-fallocate.m4 b/config/kernel-fallocate.m4
index d551276c7..6ac5ae65c 100644
--- a/config/kernel-fallocate.m4
+++ b/config/kernel-fallocate.m4
@@ -39,10 +39,31 @@ AC_DEFUN([ZFS_AC_KERNEL_INODE_FALLOCATE], [
 ])
 
 dnl #
+dnl # PaX Linux 2.6.38 - 3.x API
+dnl #
+AC_DEFUN([ZFS_AC_PAX_KERNEL_FILE_FALLOCATE], [
+	AC_MSG_CHECKING([whether fops->fallocate() exists])
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+	],[
+		long (*fallocate) (struct file *, int, loff_t, loff_t) = NULL;
+		struct file_operations_no_const fops __attribute__ ((unused)) = {
+			.fallocate = fallocate,
+		};
+	],[
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_FILE_FALLOCATE, 1, [fops->fallocate() exists])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
+
+dnl #
 dnl # The fallocate callback was moved from the inode_operations
 dnl # structure to the file_operations structure.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_FALLOCATE], [
 	ZFS_AC_KERNEL_FILE_FALLOCATE
 	ZFS_AC_KERNEL_INODE_FALLOCATE
+	ZFS_AC_PAX_KERNEL_FILE_FALLOCATE
 ])
diff --git a/config/kernel-fsync.m4 b/config/kernel-fsync.m4
index 862b89782..ca00d93be 100644
--- a/config/kernel-fsync.m4
+++ b/config/kernel-fsync.m4
@@ -37,7 +37,7 @@ AC_DEFUN([ZFS_AC_KERNEL_FSYNC_WITHOUT_DENTRY], [
 ])
 
 dnl #
-dnl # Linux 3.1 -x 3.x API
+dnl # Linux 3.1 - 3.x API
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_FSYNC_RANGE], [
 	ZFS_LINUX_TRY_COMPILE([
@@ -55,9 +55,69 @@ AC_DEFUN([ZFS_AC_KERNEL_FSYNC_RANGE], [
 	])
 ])
 
+dnl #
+dnl # PaX Linux 2.6.x - 2.6.34 API
+dnl #
+AC_DEFUN([ZFS_AC_PAX_KERNEL_FSYNC_WITH_DENTRY], [
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+	],[
+		int (*fsync) (struct file *, struct dentry *, int) = NULL;
+		file_operations_no_const fops __attribute__ ((unused));
+
+		fops.fsync = fsync;
+	],[
+		AC_MSG_RESULT([dentry])
+		AC_DEFINE(HAVE_FSYNC_WITH_DENTRY, 1,
+			[fops->fsync() with dentry])
+	],[
+	])
+])
+
+dnl #
+dnl # PaX Linux 2.6.35 - Linux 3.0 API
+dnl #
+AC_DEFUN([ZFS_AC_PAX_KERNEL_FSYNC_WITHOUT_DENTRY], [
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+	],[
+		int (*fsync) (struct file *, int) = NULL;
+		file_operations_no_const fops __attribute__ ((unused));
+
+		fops.fsync = fsync;
+	],[
+		AC_MSG_RESULT([no dentry])
+		AC_DEFINE(HAVE_FSYNC_WITHOUT_DENTRY, 1,
+			[fops->fsync() without dentry])
+	],[
+	])
+])
+
+dnl #
+dnl # PaX Linux 3.1 - 3.x API
+dnl #
+AC_DEFUN([ZFS_AC_PAX_KERNEL_FSYNC_RANGE], [
+	ZFS_LINUX_TRY_COMPILE([
+		#include <linux/fs.h>
+	],[
+		int (*fsync) (struct file *, loff_t, loff_t, int) = NULL;
+		file_operations_no_const fops __attribute__ ((unused));
+
+		fops.fsync = fsync;
+	],[
+		AC_MSG_RESULT([range])
+		AC_DEFINE(HAVE_FSYNC_RANGE, 1,
+			[fops->fsync() with range])
+	],[
+	])
+])
+
 AC_DEFUN([ZFS_AC_KERNEL_FSYNC], [
 	AC_MSG_CHECKING([whether fops->fsync() wants])
 	ZFS_AC_KERNEL_FSYNC_WITH_DENTRY
 	ZFS_AC_KERNEL_FSYNC_WITHOUT_DENTRY
 	ZFS_AC_KERNEL_FSYNC_RANGE
+	ZFS_AC_PAX_KERNEL_FSYNC_WITH_DENTRY
+	ZFS_AC_PAX_KERNEL_FSYNC_WITHOUT_DENTRY
+	ZFS_AC_PAX_KERNEL_FSYNC_RANGE
 ])