block: add native support for NFS

This patch adds native support for accessing images on NFS
shares without the requirement to actually mount the entire
NFS share on the host.

NFS Images can simply be specified by an url of the form:
nfs://<host>/<export>/<filename>[?param=value[&param2=value2[&...]]]

For example:
qemu-img create -f qcow2 nfs://10.0.0.1/qemu-images/test.qcow2

You need LibNFS from Ronnie Sahlberg available at:
   git://github.com/sahlberg/libnfs.git
for this to work.

During configure it is automatically probed for libnfs and support
is enabled on-the-fly. You can forbid or enforce libnfs support
with --disable-libnfs or --enable-libnfs respectively.

Due to NFS restrictions you might need to execute your binaries
as root, allow them to open priviledged ports (<1024) or specify
insecure option on the NFS server.

For additional information on ROOT vs. non-ROOT operation and URL
format + parameters see:
   https://raw.github.com/sahlberg/libnfs/master/README

Supported by qemu are the uid, gid and tcp-syncnt URL parameters.

LibNFS currently support NFS version 3 only.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/configure b/configure
index 236764a3bd..5b20ce6139 100755
--- a/configure
+++ b/configure
@@ -251,6 +251,7 @@ vss_win32_sdk=""
 win_sdk="no"
 want_tools="yes"
 libiscsi=""
+libnfs=""
 coroutine=""
 coroutine_pool=""
 seccomp=""
@@ -840,6 +841,10 @@ for opt do
   ;;
   --enable-libiscsi) libiscsi="yes"
   ;;
+  --disable-libnfs) libnfs="no"
+  ;;
+  --enable-libnfs) libnfs="yes"
+  ;;
   --enable-profiler) profiler="yes"
   ;;
   --disable-cocoa) cocoa="no"
@@ -1229,6 +1234,8 @@ Advanced options (experts only):
   --enable-rbd             enable building the rados block device (rbd)
   --disable-libiscsi       disable iscsi support
   --enable-libiscsi        enable iscsi support
+  --disable-libnfs         disable nfs support
+  --enable-libnfs          enable nfs support
   --disable-smartcard-nss  disable smartcard nss support
   --enable-smartcard-nss   enable smartcard nss support
   --disable-libusb         disable libusb (for usb passthrough)
@@ -3600,6 +3607,20 @@ elif test "$debug" = "no" ; then
   CFLAGS="-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
 fi
 
+##########################################
+# Do we have libnfs
+if test "$libnfs" != "no" ; then
+  if $pkg_config --atleast-version=1.9.2 libnfs; then
+    libnfs="yes"
+    libnfs_libs=$($pkg_config --libs libnfs)
+    LIBS="$LIBS $libnfs_libs"
+  else
+    if test "$libnfs" = "yes" ; then
+      feature_not_found "libnfs"
+    fi
+    libnfs="no"
+  fi
+fi
 
 # Disable zero malloc errors for official releases unless explicitly told to
 # enable/disable
@@ -3829,6 +3850,7 @@ echo "libiscsi support  $libiscsi (1.4.0)"
 else
 echo "libiscsi support  $libiscsi"
 fi
+echo "libnfs support    $libnfs"
 echo "build guest agent $guest_agent"
 echo "QGA VSS support   $guest_agent_with_vss"
 echo "seccomp support   $seccomp"
@@ -4165,6 +4187,10 @@ if test "$libiscsi" = "yes" ; then
   fi
 fi
 
+if test "$libnfs" = "yes" ; then
+  echo "CONFIG_LIBNFS=y" >> $config_host_mak
+fi
+
 if test "$seccomp" = "yes"; then
   echo "CONFIG_SECCOMP=y" >> $config_host_mak
 fi