meson: move libmpathpersist test

This is the first compiler/linker test that has been moved to Meson.
Add more section headings to keep things clearer.

This also fixes static linking to libmpathpersist, which has a
dependency on libmultipath but no pkg-config file to describe it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

configure

@@ -403,7 +403,7 @@ netmap="no"
 sdl="auto"
 sdl_image="auto"
 virtfs=""
-mpath=""
+mpath="auto"
 vnc="enabled"
 sparse="no"
 vde=""
@@ -1116,9 +1116,9 @@ for opt do
   ;;
   --enable-virtfs) virtfs="yes"
   ;;
-  --disable-mpath) mpath="no"
+  --disable-mpath) mpath="disabled"
   ;;
-  --enable-mpath) mpath="yes"
+  --enable-mpath) mpath="enabled"
   ;;
   --disable-vnc) vnc="disabled"
   ;;
@@ -3852,57 +3852,6 @@ if test "$modules" = yes; then
     fi
 fi
 
-##########################################
-# libmpathpersist probe
-
-if test "$mpath" != "no" ; then
-  # probe for the new API
-  cat > $TMPC <<EOF
-#include <libudev.h>
-#include <mpath_persist.h>
-unsigned mpath_mx_alloc_len = 1024;
-int logsink;
-static struct config *multipath_conf;
-extern struct udev *udev;
-extern struct config *get_multipath_config(void);
-extern void put_multipath_config(struct config *conf);
-struct udev *udev;
-struct config *get_multipath_config(void) { return multipath_conf; }
-void put_multipath_config(struct config *conf) { }
-
-int main(void) {
-    udev = udev_new();
-    multipath_conf = mpath_lib_init();
-    return 0;
-}
-EOF
-  if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
-    mpathpersist=yes
-    mpathpersist_new_api=yes
-  else
-    # probe for the old API
-    cat > $TMPC <<EOF
-#include <libudev.h>
-#include <mpath_persist.h>
-unsigned mpath_mx_alloc_len = 1024;
-int logsink;
-int main(void) {
-    struct udev *udev = udev_new();
-    mpath_lib_init(udev);
-    return 0;
-}
-EOF
-    if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
-      mpathpersist=yes
-      mpathpersist_new_api=no
-    else
-      mpathpersist=no
-    fi
-  fi
-else
-  mpathpersist=no
-fi
-
 ##########################################
 # pthread probe
 PTHREADLIBS_LIST="-pthread -lpthread -lpthreadGC2"
@@ -6337,23 +6286,11 @@ if test "$softmmu" = yes ; then
       fi
       virtfs=no
     fi
-    if test "$mpath" != no && test "$mpathpersist" = yes ; then
-      mpath=yes
-    else
-      if test "$mpath" = yes; then
-        error_exit "Multipath requires libmpathpersist devel"
-      fi
-      mpath=no
-    fi
   else
     if test "$virtfs" = yes; then
       error_exit "VirtFS is supported only on Linux"
     fi
     virtfs=no
-    if test "$mpath" = yes; then
-      error_exit "Multipath is supported only on Linux"
-    fi
-    mpath=no
   fi
 fi
 
@@ -6894,12 +6831,6 @@ fi
 if test "$virtfs" = "yes" ; then
   echo "CONFIG_VIRTFS=y" >> $config_host_mak
 fi
-if test "$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" >> $config_host_mak
 fi
@@ -7988,7 +7919,7 @@ NINJA=${ninja:-$PWD/ninjatool} $meson setup \
         -Dstrip=$(if test "$strip_opt" = yes; then echo true; else echo false; fi) \
         -Db_pie=$(if test "$pie" = yes; then echo true; else echo false; fi) \
         -Db_coverage=$(if test "$gcov" = yes; then echo true; else echo false; fi) \
-	-Dsdl=$sdl -Dsdl_image=$sdl_image \
+	-Dmpath=$mpath -Dsdl=$sdl -Dsdl_image=$sdl_image \
 	-Dvnc=$vnc -Dvnc_sasl=$vnc_sasl -Dvnc_jpeg=$vnc_jpeg -Dvnc_png=$vnc_png \
 	-Dgettext=$gettext -Dxkbcommon=$xkbcommon -Du2f=$u2f\
         $cross_arg \

meson.build

@@ -86,6 +86,14 @@ if 'SPARSE_CFLAGS' in config_host
                        'compile_commands.json'])
 endif
 
+###########################################
+# Target-specific checks and dependencies #
+###########################################
+
+if targetos != 'linux' and get_option('mpath').enabled()
+  error('Multipath is supported only on Linux')
+endif
+
 m = cc.find_library('m', required: false)
 util = cc.find_library('util', required: false)
 winmm = []
@@ -117,6 +125,11 @@ elif targetos == 'haiku'
             cc.find_library('network'),
             cc.find_library('bsd')]
 endif
+
+################
+# Dependencies #
+################
+
 # The path to glib.h is added to all compilation commands.  This was
 # grandfathered in from the QEMU Makefiles.
 add_project_arguments(config_host['GLIB_CFLAGS'].split(),
@@ -223,10 +236,6 @@ if 'CONFIG_SPICE' in config_host
                              link_args: config_host['SPICE_LIBS'].split())
 endif
 rt = cc.find_library('rt', required: false)
-libmpathpersist = not_found
-if config_host.has_key('CONFIG_MPATH')
-  libmpathpersist = cc.find_library('mpathpersist')
-endif
 libdl = not_found
 if 'CONFIG_PLUGIN' in config_host
   libdl = cc.find_library('dl', required: true)
@@ -258,8 +267,64 @@ if 'CONFIG_CURL' in config_host
 endif
 libudev = not_found
 if targetos == 'linux' and (have_system or have_tools)
-  libudev = dependency('libudev', static: enable_static)
+  libudev = dependency('libudev',
+                       required: get_option('mpath').enabled(),
+                       static: enable_static)
 endif
+
+mpathpersist = not_found
+mpathpersist_new_api = false
+if targetos == 'linux' and have_tools and not get_option('mpath').disabled()
+  mpath_test_source_new = '''
+    #include <libudev.h>
+    #include <mpath_persist.h>
+    unsigned mpath_mx_alloc_len = 1024;
+    int logsink;
+    static struct config *multipath_conf;
+    extern struct udev *udev;
+    extern struct config *get_multipath_config(void);
+    extern void put_multipath_config(struct config *conf);
+    struct udev *udev;
+    struct config *get_multipath_config(void) { return multipath_conf; }
+    void put_multipath_config(struct config *conf) { }
+    int main(void) {
+        udev = udev_new();
+        multipath_conf = mpath_lib_init();
+        return 0;
+    }'''
+  mpath_test_source_old = '''
+      #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;
+      }'''
+  libmultipath = cc.find_library('multipath',
+                                 required: get_option('mpath'),
+                                 static: enable_static)
+  libmpathpersist = cc.find_library('mpathpersist',
+                                    required: get_option('mpath'),
+                                    static: enable_static)
+  if libmultipath.found() and libmpathpersist.found() and libudev.found()
+    mpathlibs = [libmultipath, libmpathpersist, libudev]
+    if cc.links(mpath_test_source_new, dependencies: mpathlibs)
+      mpathpersist = declare_dependency(dependencies: mpathlibs)
+      mpathpersist_new_api = true
+    elif cc.links(mpath_test_source_old, dependencies: mpathlibs)
+      mpathpersist = declare_dependency(dependencies: mpathlibs)
+    else
+      if get_option('mpath').enabled()
+        error('Cannot detect libmpathpersist API')
+      else
+        warning('Cannot detect libmpathpersist API, disabling')
+      endif
+    endif
+  endif
+endif
+
 brlapi = not_found
 if 'CONFIG_BRLAPI' in config_host
   brlapi = declare_dependency(link_args: config_host['BRLAPI_LIBS'].split())
@@ -441,6 +506,8 @@ has_gettid = cc.has_function('gettid')
 # Create config-host.h
 
 config_host_data.set('CONFIG_LIBUDEV', libudev.found())
+config_host_data.set('CONFIG_MPATH', mpathpersist.found())
+config_host_data.set('CONFIG_MPATH_NEW_API', mpathpersist_new_api)
 config_host_data.set('CONFIG_SDL', sdl.found())
 config_host_data.set('CONFIG_SDL_IMAGE', sdl_image.found())
 config_host_data.set('CONFIG_VNC', vnc.found())
@@ -1205,7 +1272,7 @@ if have_tools
 
     executable('qemu-pr-helper', files('scsi/qemu-pr-helper.c', 'scsi/utils.c'),
                dependencies: [authz, crypto, io, qom, qemuutil,
-                              libcap_ng, libudev, libmpathpersist],
+                              libcap_ng, mpathpersist],
                install: true)
   endif
 
@@ -1342,7 +1409,7 @@ summary_info += {'Audio drivers':     config_host['CONFIG_AUDIO_DRIVERS']}
 summary_info += {'Block whitelist (rw)': config_host['CONFIG_BDRV_RW_WHITELIST']}
 summary_info += {'Block whitelist (ro)': config_host['CONFIG_BDRV_RO_WHITELIST']}
 summary_info += {'VirtFS support':    config_host.has_key('CONFIG_VIRTFS')}
-summary_info += {'Multipath support': config_host.has_key('CONFIG_MPATH')}
+summary_info += {'Multipath support': mpathpersist.found()}
 summary_info += {'VNC support':       vnc.found()}
 if vnc.found()
   summary_info += {'VNC SASL support':  sasl.found()}

meson_options.txt

@@ -6,6 +6,8 @@ option('docdir', type : 'string', value : 'doc',
 option('gettext', type : 'boolean', value : true,
        description: 'Localization of the GTK+ user interface')
 
+option('mpath', type : 'feature', value : 'auto',
+       description: 'Multipath persistent reservation passthrough')
 option('sdl', type : 'feature', value : 'auto',
        description: 'SDL user interface')
 option('sdl_image', type : 'feature', value : 'auto',