LU-766 Fix sops->statfs() autoconf check

Building with RHEL6.2 beta (kernel-2.6.32-204) exposed that the
HAVE_STATFS_DENTRY_PARAM autoconf check was incorrect. The test
was setup to check the first argument of vfs_statfs() function.
However, the conditional code itself doesn't use the vfs_statfs()
function it registers a function with the sops->statfs() callback.

Historically, this always worked because both of these prototypes
were changed in a single upstream kernel commit (726c3342). However,
as of RHEL6.2 the vfs_statfs() function changed again and the
sops->statfs() callback stayed the same. The vfs_statfs() function
now takes a path structure as the first parameter.

This was fixed by simply updating the autoconf test to check the
prototype of the function were going to actually use.

Change-Id: I0cf36e758fd9c85609c47c13dbdf249321664b26
Signed-off-by: Yang Sheng <ys@whamcloud.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-on: http://review.whamcloud.com/1527
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Lai Siyao <laisiyao@whamcloud.com>
Reviewed-by: Niu Yawei <niu@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>

diff --git a/lustre/autoconf/lustre-core.m4 b/lustre/autoconf/lustre-core.m4
index de554d4..69371f7 100644 (file)
--- a/lustre/autoconf/lustre-core.m4
+++ b/lustre/autoconf/lustre-core.m4
@@ -965,22 +965,27 @@ LB_LINUX_TRY_COMPILE([
 
 #
 # LC_STATFS_DENTRY_PARAM
-# starting from 2.6.18 linux kernel uses dentry instead of
-# super_block for first vfs_statfs argument
+# starting from 2.6.18 linux kernel uses dentry instead of super_block
+# for the first parameter of the super_operations->statfs() callback.
+#
 #
 AC_DEFUN([LC_STATFS_DENTRY_PARAM],
-[AC_MSG_CHECKING([first vfs_statfs parameter is dentry])
+[AC_MSG_CHECKING([if super_ops.statfs() first parameter is dentry])
+tmp_flags="$EXTRA_KCFLAGS"
+EXTRA_KCFLAGS="-Werror"
 LB_LINUX_TRY_COMPILE([
         #include <linux/fs.h>
 ],[
-       int vfs_statfs(struct dentry *, struct kstatfs *);
+        struct super_operations *sop = NULL;
+        sop->statfs((struct dentry *)0, (struct kstatfs*)0);
 ],[
         AC_DEFINE(HAVE_STATFS_DENTRY_PARAM, 1,
-                [first parameter of vfs_statfs is dentry])
+                [super_ops.statfs() first parameter is dentry])
         AC_MSG_RESULT([yes])
 ],[
         AC_MSG_RESULT([no])
 ])
+EXTRA_KCFLAGS="$tmp_flags"
 ])
 
 #