qemu-nbd: Add --bitmap=NAME option

Having to fire up qemu, then use QMP commands for nbd-server-start
and nbd-server-add, just to expose a persistent dirty bitmap, is
rather tedious.  Make it possible to expose a dirty bitmap using
just qemu-nbd (of course, for now this only works when qemu-nbd is
visiting a BDS formatted as qcow2).

Of course, any good feature also needs unit testing, so expand
iotest 223 to cover it.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190111194720.15671-9-eblake@redhat.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/qemu-nbd.c b/qemu-nbd.c
index 1552274c18..51b55f2e06 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -95,6 +95,7 @@ static void usage(const char *name)
 "Exposing part of the image:\n"
 "  -o, --offset=OFFSET       offset into the image\n"
 "  -P, --partition=NUM       only expose partition NUM\n"
+"  -B, --bitmap=NAME         expose a persistent dirty bitmap\n"
 "\n"
 "General purpose options:\n"
 "  --object type,id=ID,...   define an object such as 'secret' for providing\n"
@@ -509,7 +510,7 @@ int main(int argc, char **argv)
     off_t fd_size;
     QemuOpts *sn_opts = NULL;
     const char *sn_id_or_name = NULL;
-    const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:";
+    const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:B:";
     struct option lopt[] = {
         { "help", no_argument, NULL, 'h' },
         { "version", no_argument, NULL, 'V' },
@@ -519,6 +520,7 @@ int main(int argc, char **argv)
         { "offset", required_argument, NULL, 'o' },
         { "read-only", no_argument, NULL, 'r' },
         { "partition", required_argument, NULL, 'P' },
+        { "bitmap", required_argument, NULL, 'B' },
         { "connect", required_argument, NULL, 'c' },
         { "disconnect", no_argument, NULL, 'd' },
         { "snapshot", no_argument, NULL, 's' },
@@ -558,6 +560,7 @@ int main(int argc, char **argv)
     QDict *options = NULL;
     const char *export_name = ""; /* Default export name */
     const char *export_description = NULL;
+    const char *bitmap = NULL;
     const char *tlscredsid = NULL;
     bool imageOpts = false;
     bool writethrough = true;
@@ -695,6 +698,9 @@ int main(int argc, char **argv)
                 exit(EXIT_FAILURE);
             }
             break;
+        case 'B':
+            bitmap = optarg;
+            break;
         case 'k':
             sockpath = optarg;
             if (sockpath[0] != '/') {
@@ -1016,7 +1022,7 @@ int main(int argc, char **argv)
     }
 
     export = nbd_export_new(bs, dev_offset, fd_size, export_name,
-                            export_description, NULL, nbdflags,
+                            export_description, bitmap, nbdflags,
                             nbd_export_closed, writethrough, NULL,
                             &error_fatal);