nbd: Update qapi to support exporting multiple bitmaps

Since 'block-export-add' is new to 5.2, we can still tweak the
interface; there, allowing 'bitmaps':['str'] is nicer than
'bitmap':'str'.  This wires up the qapi and qemu-nbd changes to permit
passing multiple bitmaps as distinct metadata contexts that the NBD
client may request, but the actual support for more than one will
require a further patch to the server.

Note that there are no changes made to the existing deprecated
'nbd-server-add' command; this required splitting the QAPI type
BlockExportOptionsNbd, which fortunately does not affect QMP
introspection.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201027050556.269064-5-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/nbd/server.c b/nbd/server.c
index 08b621f70a..8d01662b45 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1474,6 +1474,7 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
     uint64_t perm, shared_perm;
     bool readonly = !exp_args->writable;
     bool shared = !exp_args->writable;
+    strList *bitmaps;
     int ret;
 
     assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD);
@@ -1533,12 +1534,18 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
     }
     exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE);
 
-    if (arg->bitmap) {
+    /* XXX Allow more than one bitmap */
+    if (arg->bitmaps && arg->bitmaps->next) {
+        error_setg(errp, "multiple bitmaps per export not supported yet");
+        return -EOPNOTSUPP;
+    }
+    for (bitmaps = arg->bitmaps; bitmaps; bitmaps = bitmaps->next) {
+        const char *bitmap = bitmaps->value;
         BlockDriverState *bs = blk_bs(blk);
         BdrvDirtyBitmap *bm = NULL;
 
         while (bs) {
-            bm = bdrv_find_dirty_bitmap(bs, arg->bitmap);
+            bm = bdrv_find_dirty_bitmap(bs, bitmap);
             if (bm != NULL) {
                 break;
             }
@@ -1548,7 +1555,7 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
 
         if (bm == NULL) {
             ret = -ENOENT;
-            error_setg(errp, "Bitmap '%s' is not found", arg->bitmap);
+            error_setg(errp, "Bitmap '%s' is not found", bitmap);
             goto fail;
         }
 
@@ -1562,15 +1569,15 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
             ret = -EINVAL;
             error_setg(errp,
                        "Enabled bitmap '%s' incompatible with readonly export",
-                       arg->bitmap);
+                       bitmap);
             goto fail;
         }
 
         bdrv_dirty_bitmap_set_busy(bm, true);
         exp->export_bitmap = bm;
-        assert(strlen(arg->bitmap) <= BDRV_BITMAP_MAX_NAME_SIZE);
+        assert(strlen(bitmap) <= BDRV_BITMAP_MAX_NAME_SIZE);
         exp->export_bitmap_context = g_strdup_printf("qemu:dirty-bitmap:%s",
-                                                     arg->bitmap);
+                                                     bitmap);
         assert(strlen(exp->export_bitmap_context) < NBD_MAX_STRING_SIZE);
     }