qemu-pr-helper: Fix build on CentOS 7

After commit b3f1c8c413bc83e4a2cc7a63e4eddf9fe6449052 "qemu-pr-helper: use new
libmultipath API", QEMU started using new libmultipath API, which is not
available on CentOS 7.x.

This fixes that by probing the new libmultipath API in configure.  If it fails,
then try probing the old API.  If it fails, then consider libmultipath not
available.

With this, configure script defines CONFIG_MPATH_NEW_API that is used in
scsi/qemu-pr-helper.c to use the new libmultipath API.

Fixes: b3f1c8c413bc83e4a2cc7a63e4eddf9fe6449052
BugLink: https://bugs.launchpad.net/qemu/+bug/1786343
Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Message-Id: <20180810141116.24016-1-muriloo@linux.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/configure b/configure
index e7bddc04b0480109bf224755c92ee1580bd97ada..af0c1490959acd27389fb9db9b29fb84f2ef1fa7 100755 (executable)
--- a/configure
+++ b/configure
@@ -3612,6 +3612,7 @@ fi
 # libmpathpersist probe
 
 if test "$mpath" != "no" ; then
+  # probe for the new API
   cat > $TMPC <<EOF
 #include <libudev.h>
 #include <mpath_persist.h>
@@ -3633,8 +3634,26 @@ int main(void) {
 EOF
   if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
     mpathpersist=yes
+    mpathpersist_new_api=yes
   else
-    mpathpersist=no
+    # probe for the old API
+    cat > $TMPC <<EOF
+#include <libudev.h>
+#include <mpath_persist.h>
+unsigned mpath_mx_alloc_len = 1024;
+int logsink;
+int main(void) {
+    struct udev *udev = udev_new();
+    mpath_lib_init(udev);
+    return 0;
+}
+EOF
+    if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
+      mpathpersist=yes
+      mpathpersist_new_api=no
+    else
+      mpathpersist=no
+    fi
   fi
 else
   mpathpersist=no
@@ -6495,6 +6514,9 @@ if test "$virtfs" = "yes" ; then
 fi
 if test "$mpath" = "yes" ; then
   echo "CONFIG_MPATH=y" >> $config_host_mak
+  if test "$mpathpersist_new_api" = "yes"; then
+    echo "CONFIG_MPATH_NEW_API=y" >> $config_host_mak
+  fi
 fi
 if test "$vhost_scsi" = "yes" ; then
   echo "CONFIG_VHOST_SCSI=y" >> $config_host_mak

diff --git a/scsi/qemu-pr-helper.c b/scsi/qemu-pr-helper.c
index 1528a712a0cf9c8ad4221ddd0d33e1173c771f05..ed037aabeec451922faa1a87df3ea26d7a391c59 100644 (file)
--- a/scsi/qemu-pr-helper.c
+++ b/scsi/qemu-pr-helper.c
@@ -301,7 +301,11 @@ void put_multipath_config(struct config *conf)
 static void multipath_pr_init(void)
 {
     udev = udev_new();
+#ifdef CONFIG_MPATH_NEW_API
     multipath_conf = mpath_lib_init();
+#else
+    mpath_lib_init(udev);
+#endif
 }
 
 static int is_mpath(int fd)