block migration: Allow compile time disable

Many users now prefer to use drive_mirror over NBD as an
alternative to the older migrate -b option; drive_mirror is
more complex to setup but gives you more options (e.g. only
migrating some of the disks if some of them are shared).

Allow the large chunk of block migration code to be compiled
out for those who don't use it.

Based on a downstream-patch we've had for a while by Jeff Cody.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
--

- When compiled out, allow seting block only with false value (eric)

diff --git a/configure b/configure
index 139638e922e00fb0df971dc505cfa997944aac1c..1a5ee4b909b8c82b89bebd956382b34640a243d0 100755 (executable)
--- a/configure
+++ b/configure
@@ -316,6 +316,7 @@ vte=""
 virglrenderer=""
 tpm="yes"
 libssh2=""
+live_block_migration="yes"
 numa=""
 tcmalloc="no"
 jemalloc="no"
@@ -1169,6 +1170,10 @@ for opt do
   ;;
   --enable-libssh2) libssh2="yes"
   ;;
+  --disable-live-block-migration) live_block_migration="no"
+  ;;
+  --enable-live-block-migration) live_block_migration="yes"
+  ;;
   --disable-numa) numa="no"
   ;;
   --enable-numa) numa="yes"
@@ -1401,6 +1406,7 @@ disabled with --disable-FEATURE, default is enabled if available:
   libnfs          nfs support
   smartcard       smartcard support (libcacard)
   libusb          libusb (for usb passthrough)
+  live-block-migration   Block migration in the main migration stream
   usb-redir       usb network redirection support
   lzo             support of lzo compression library
   snappy          support of snappy compression library
@@ -5216,6 +5222,7 @@ echo "TPM support       $tpm"
 echo "libssh2 support   $libssh2"
 echo "TPM passthrough   $tpm_passthrough"
 echo "QOM debugging     $qom_cast_debug"
+echo "Live block migration $live_block_migration"
 echo "lzo support       $lzo"
 echo "snappy support    $snappy"
 echo "bzip2 support     $bzip2"
@@ -5782,6 +5789,10 @@ if test "$libssh2" = "yes" ; then
   echo "LIBSSH2_LIBS=$libssh2_libs" >> $config_host_mak
 fi
 
+if test "$live_block_migration" = "yes" ; then
+  echo "CONFIG_LIVE_BLOCK_MIGRATION=y" >> $config_host_mak
+fi
+
 # USB host support
 if test "$libusb" = "yes"; then
   echo "HOST_USB=libusb legacy" >> $config_host_mak

diff --git a/include/migration/block.h b/include/migration/block.h
index 5225af9d2b6a2a0d6f8057680b22263cdc2ef7f9..28cff53a23159f2701c1df140fb7d2c59444db4f 100644 (file)
--- a/include/migration/block.h
+++ b/include/migration/block.h
@@ -14,12 +14,34 @@
 #ifndef MIGRATION_BLOCK_H
 #define MIGRATION_BLOCK_H
 
+#ifdef CONFIG_LIVE_BLOCK_MIGRATION
 void blk_mig_init(void);
 int blk_mig_active(void);
 uint64_t blk_mig_bytes_transferred(void);
 uint64_t blk_mig_bytes_remaining(void);
 uint64_t blk_mig_bytes_total(void);
 
-void migrate_set_block_enabled(bool value, Error **errp);
+#else
+static inline void blk_mig_init(void) { }
+static inline int blk_mig_active(void)
+{
+    return false;
+}
+static inline uint64_t blk_mig_bytes_transferred(void)
+{
+    return 0;
+}
+
+static inline uint64_t blk_mig_bytes_remaining(void)
+{
+    return 0;
+}
 
+static inline uint64_t blk_mig_bytes_total(void)
+{
+    return 0;
+}
+#endif /* CONFIG_LIVE_BLOCK_MIGRATION */
+
+void migrate_set_block_enabled(bool value, Error **errp);
 #endif /* MIGRATION_BLOCK_H */

diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index c1920b6fc0d935e2e224c81148a560211d458380..00a3f4a1d9e52b24b260f6d34ea71b0584c53282 100644 (file)
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -9,5 +9,5 @@ common-obj-y += qjson.o
 
 common-obj-$(CONFIG_RDMA) += rdma.o
 
-common-obj-y += block.o
+common-obj-$(CONFIG_LIVE_BLOCK_MIGRATION) += block.o
 

diff --git a/migration/migration.c b/migration/migration.c
index ed66158377d67d2f3ad19c21a76b132d43514ad6..2feeee8787924d188fdc8a083bdcc357c666ed78 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -547,6 +547,11 @@ MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
 
     caps = NULL; /* silence compiler warning */
     for (i = 0; i < MIGRATION_CAPABILITY__MAX; i++) {
+#ifndef CONFIG_LIVE_BLOCK_MIGRATION
+        if (i == MIGRATION_CAPABILITY_BLOCK) {
+            continue;
+        }
+#endif
         if (i == MIGRATION_CAPABILITY_X_COLO && !colo_supported()) {
             continue;
         }
@@ -763,6 +768,15 @@ void qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
     }
 
     for (cap = params; cap; cap = cap->next) {
+#ifndef CONFIG_LIVE_BLOCK_MIGRATION
+        if (cap->value->capability == MIGRATION_CAPABILITY_BLOCK
+            && cap->value->state) {
+            error_setg(errp, "QEMU compiled without old-style (blk/-b, inc/-i) "
+                       "block migration");
+            error_append_hint(errp, "Use drive_mirror+NBD instead.\n");
+            continue;
+        }
+#endif
         if (cap->value->capability == MIGRATION_CAPABILITY_X_COLO) {
             if (!colo_supported()) {
                 error_setg(errp, "COLO is not currently supported, please"