block: Skip implicit nodes in query-block/blockstats

Commits 0db832f and 6cdbceb introduced the automatic insertion of filter nodes above the top layer of mirror and commit block jobs. The assumption made there was that since libvirt doesn't do node-level management of the block layer yet, it shouldn't be affected by added nodes. This is true as far as commands issued by libvirt are concerned. It only uses BlockBackend names to address nodes, so any operations it performs still operate on the root of the tree as intended. However, the assumption breaks down when you consider query commands, which return data for the wrong node now. These commands also return information on some child nodes (bs->file and/or bs->backing), which libvirt does make use of, and which refer to the wrong nodes, too. One of the consequences is that oVirt gets wrong information about the image size and stops the VM in response as long as a mirror or commit job is running: https://bugzilla.redhat.com/show_bug.cgi?id=1470634 This patch fixes the problem by hiding the implicit nodes created automatically by the mirror and commit block jobs in the output of query-block and BlockBackend-based query-blockstats as long as the user doesn't indicate that they are aware of those nodes by providing a node name for them in the QMP command to start the block job. The node-based commands query-named-block-nodes and query-blockstats with query-nodes=true still show all nodes, including implicit ones. This ensures that users that are capable of node-level management can still access the full information; users that only know BlockBackends won't use these commands. Cc: [email protected] Signed-off-by: Kevin Wolf <[email protected]> Reviewed-by: Peter Krempa <[email protected]> Reviewed-by: Max Reitz <[email protected]> Tested-by: Eric Blake <[email protected]>
mattkelly · Jul 24, 2017 · d3c8c67 · d3c8c67
1 parent 24bae02
commit d3c8c67
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Showing 11 changed files with 108 additions and 28 deletions.
diff --git a/block.c b/block.c
@@ -3973,19 +3973,6 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
     return retval;
 }
 
-int bdrv_get_backing_file_depth(BlockDriverState *bs)
-{
-    if (!bs->drv) {
-        return 0;
-    }
-
-    if (!bs->backing) {
-        return 0;
-    }
-
-    return 1 + bdrv_get_backing_file_depth(bs->backing->bs);
-}
-
 void bdrv_init(void)
 {
     module_call_init(MODULE_INIT_BLOCK);

diff --git a/block/commit.c b/block/commit.c
@@ -346,6 +346,9 @@ void commit_start(const char *job_id, BlockDriverState *bs,
     if (commit_top_bs == NULL) {
         goto fail;
     }
+    if (!filter_node_name) {
+        commit_top_bs->implicit = true;
+    }
     commit_top_bs->total_sectors = top->total_sectors;
     bdrv_set_aio_context(commit_top_bs, bdrv_get_aio_context(top));
 

diff --git a/block/mirror.c b/block/mirror.c
@@ -1168,6 +1168,9 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
     if (mirror_top_bs == NULL) {
         return;
     }
+    if (!filter_node_name) {
+        mirror_top_bs->implicit = true;
+    }
     mirror_top_bs->total_sectors = bs->total_sectors;
     bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
 

diff --git a/block/qapi.c b/block/qapi.c
@@ -64,7 +64,6 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
         info->backing_file = g_strdup(bs->backing_file);
     }
 
-    info->backing_file_depth = bdrv_get_backing_file_depth(bs);
     info->detect_zeroes = bs->detect_zeroes;
 
     if (blk && blk_get_public(blk)->throttle_state) {
@@ -125,6 +124,7 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
 
     bs0 = bs;
     p_image_info = &info->image;
+    info->backing_file_depth = 0;
     while (1) {
         Error *local_err = NULL;
         bdrv_query_image_info(bs0, p_image_info, &local_err);
@@ -133,13 +133,21 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
             qapi_free_BlockDeviceInfo(info);
             return NULL;
         }
+
         if (bs0->drv && bs0->backing) {
+            info->backing_file_depth++;
             bs0 = bs0->backing->bs;
             (*p_image_info)->has_backing_image = true;
             p_image_info = &((*p_image_info)->backing_image);
         } else {
             break;
         }
+
+        /* Skip automatically inserted nodes that the user isn't aware of for
+         * query-block (blk != NULL), but not for query-named-block-nodes */
+        while (blk && bs0 && bs0->drv && bs0->implicit) {
+            bs0 = backing_bs(bs0);
+        }
     }
 
     return info;
@@ -324,6 +332,11 @@ static void bdrv_query_info(BlockBackend *blk, BlockInfo **p_info,
     BlockDriverState *bs = blk_bs(blk);
     char *qdev;
 
+    /* Skip automatically inserted nodes that the user isn't aware of */
+    while (bs && bs->drv && bs->implicit) {
+        bs = backing_bs(bs);
+    }
+
     info->device = g_strdup(blk_name(blk));
     info->type = g_strdup("unknown");
     info->locked = blk_dev_is_medium_locked(blk);
@@ -434,8 +447,8 @@ static void bdrv_query_blk_stats(BlockDeviceStats *ds, BlockBackend *blk)
     }
 }
 
-static BlockStats *bdrv_query_bds_stats(const BlockDriverState *bs,
-                                 bool query_backing)
+static BlockStats *bdrv_query_bds_stats(BlockDriverState *bs,
+                                        bool blk_level)
 {
     BlockStats *s = NULL;
 
@@ -446,6 +459,14 @@ static BlockStats *bdrv_query_bds_stats(const BlockDriverState *bs,
         return s;
     }
 
+    /* Skip automatically inserted nodes that the user isn't aware of in
+     * a BlockBackend-level command. Stay at the exact node for a node-level
+     * command. */
+    while (blk_level && bs->drv && bs->implicit) {
+        bs = backing_bs(bs);
+        assert(bs);
+    }
+
     if (bdrv_get_node_name(bs)[0]) {
         s->has_node_name = true;
         s->node_name = g_strdup(bdrv_get_node_name(bs));
@@ -455,12 +476,12 @@ static BlockStats *bdrv_query_bds_stats(const BlockDriverState *bs,
 
     if (bs->file) {
         s->has_parent = true;
-        s->parent = bdrv_query_bds_stats(bs->file->bs, query_backing);
+        s->parent = bdrv_query_bds_stats(bs->file->bs, blk_level);
     }
 
-    if (query_backing && bs->backing) {
+    if (blk_level && bs->backing) {
         s->has_backing = true;
-        s->backing = bdrv_query_bds_stats(bs->backing->bs, query_backing);
+        s->backing = bdrv_query_bds_stats(bs->backing->bs, blk_level);
     }
 
     return s;

diff --git a/include/block/block.h b/include/block/block.h
@@ -300,7 +300,6 @@ int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
                                        int bytes, BdrvRequestFlags flags);
 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
     const char *backing_file);
-int bdrv_get_backing_file_depth(BlockDriverState *bs);
 void bdrv_refresh_filename(BlockDriverState *bs);
 int bdrv_truncate(BdrvChild *child, int64_t offset, PreallocMode prealloc,
                   Error **errp);

diff --git a/include/block/block_int.h b/include/block/block_int.h
@@ -549,6 +549,7 @@ struct BlockDriverState {
     bool sg;        /* if true, the device is a /dev/sg* */
     bool probed;    /* if true, format was probed rather than specified */
     bool force_share; /* if true, always allow all shared permissions */
+    bool implicit;  /* if true, this filter node was automatically inserted */
 
     BlockDriver *drv; /* NULL means no media */
     void *opaque;

diff --git a/qapi/block-core.json b/qapi/block-core.json
@@ -520,7 +520,8 @@
 #
 # Get a list of BlockInfo for all virtual block devices.
 #
-# Returns: a list of @BlockInfo describing each virtual block device
+# Returns: a list of @BlockInfo describing each virtual block device. Filter
+# nodes that were created implicitly are skipped over.
 #
 # Since: 0.14.0
 #
@@ -780,7 +781,8 @@
 #               information, but not "backing".
 #               If false or omitted, the behavior is as before - query all the
 #               device backends, recursively including their "parent" and
-#               "backing". (Since 2.3)
+#               "backing". Filter nodes that were created implicitly are
+#               skipped over in this mode. (Since 2.3)
 #
 # Returns: A list of @BlockStats for each virtual block devices.
 #

diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
@@ -81,7 +81,7 @@ class TestSingleDrive(ImageCommitTestCase):
         qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % mid_img, test_img)
         qemu_io('-f', 'raw', '-c', 'write -P 0xab 0 524288', backing_img)
         qemu_io('-f', iotests.imgfmt, '-c', 'write -P 0xef 524288 524288', mid_img)
-        self.vm = iotests.VM().add_drive(test_img, interface="none")
+        self.vm = iotests.VM().add_drive(test_img, "node-name=top,backing.node-name=mid,backing.backing.node-name=base", interface="none")
         self.vm.add_device("virtio-scsi-pci")
         self.vm.add_device("scsi-hd,id=scsi0,drive=drive0")
         self.vm.launch()
@@ -163,6 +163,34 @@ class TestSingleDrive(ImageCommitTestCase):
 
         self.assert_no_active_block_jobs()
 
+    # Tests that the insertion of the commit_top filter node doesn't make a
+    # difference to query-blockstat
+    def test_implicit_node(self):
+        if self.image_len == 0:
+            return
+
+        self.assert_no_active_block_jobs()
+        result = self.vm.qmp('block-commit', device='drive0', top=mid_img,
+                             base=backing_img, speed=(self.image_len / 4))
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('query-block')
+        self.assert_qmp(result, 'return[0]/inserted/file', test_img)
+        self.assert_qmp(result, 'return[0]/inserted/drv', iotests.imgfmt)
+        self.assert_qmp(result, 'return[0]/inserted/backing_file', mid_img)
+        self.assert_qmp(result, 'return[0]/inserted/backing_file_depth', 2)
+        self.assert_qmp(result, 'return[0]/inserted/image/filename', test_img)
+        self.assert_qmp(result, 'return[0]/inserted/image/backing-image/filename', mid_img)
+        self.assert_qmp(result, 'return[0]/inserted/image/backing-image/backing-image/filename', backing_img)
+
+        result = self.vm.qmp('query-blockstats')
+        self.assert_qmp(result, 'return[0]/node-name', 'top')
+        self.assert_qmp(result, 'return[0]/backing/node-name', 'mid')
+        self.assert_qmp(result, 'return[0]/backing/backing/node-name', 'base')
+
+        self.cancel_and_wait()
+        self.assert_no_active_block_jobs()
+
 class TestRelativePaths(ImageCommitTestCase):
     image_len = 1 * 1024 * 1024
     test_len = 1 * 1024 * 256

diff --git a/tests/qemu-iotests/040.out b/tests/qemu-iotests/040.out
@@ -1,5 +1,5 @@
-...........................
+.............................
 ----------------------------------------------------------------------
-Ran 27 tests
+Ran 29 tests
 
 OK
diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
@@ -42,7 +42,7 @@ class TestSingleDrive(iotests.QMPTestCase):
     def setUp(self):
         iotests.create_image(backing_img, self.image_len)
         qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % backing_img, test_img)
-        self.vm = iotests.VM().add_drive(test_img)
+        self.vm = iotests.VM().add_drive(test_img, "node-name=top,backing.node-name=base")
         if iotests.qemu_default_machine == 'pc':
             self.vm.add_drive(None, 'media=cdrom', 'ide')
         self.vm.launch()
@@ -169,6 +169,42 @@ class TestSingleDrive(iotests.QMPTestCase):
         self.assertTrue(iotests.compare_images(test_img, target_img),
                         'target image does not match source after mirroring')
 
+    # Tests that the insertion of the mirror_top filter node doesn't make a
+    # difference to query-block
+    def test_implicit_node(self):
+        self.assert_no_active_block_jobs()
+
+        result = self.vm.qmp(self.qmp_cmd, device='drive0', sync='full',
+                             target=self.qmp_target)
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('query-block')
+        self.assert_qmp(result, 'return[0]/inserted/file', test_img)
+        self.assert_qmp(result, 'return[0]/inserted/drv', iotests.imgfmt)
+        self.assert_qmp(result, 'return[0]/inserted/backing_file', backing_img)
+        self.assert_qmp(result, 'return[0]/inserted/backing_file_depth', 1)
+        self.assert_qmp(result, 'return[0]/inserted/image/filename', test_img)
+        self.assert_qmp(result, 'return[0]/inserted/image/backing-image/filename', backing_img)
+
+        result = self.vm.qmp('query-blockstats')
+        self.assert_qmp(result, 'return[0]/node-name', 'top')
+        self.assert_qmp(result, 'return[0]/backing/node-name', 'base')
+
+        self.cancel_and_wait(force=True)
+        result = self.vm.qmp('query-block')
+        self.assert_qmp(result, 'return[0]/inserted/file', test_img)
+        self.assert_qmp(result, 'return[0]/inserted/drv', iotests.imgfmt)
+        self.assert_qmp(result, 'return[0]/inserted/backing_file', backing_img)
+        self.assert_qmp(result, 'return[0]/inserted/backing_file_depth', 1)
+        self.assert_qmp(result, 'return[0]/inserted/image/filename', test_img)
+        self.assert_qmp(result, 'return[0]/inserted/image/backing-image/filename', backing_img)
+
+        result = self.vm.qmp('query-blockstats')
+        self.assert_qmp(result, 'return[0]/node-name', 'top')
+        self.assert_qmp(result, 'return[0]/backing/node-name', 'base')
+
+        self.vm.shutdown()
+
     def test_medium_not_found(self):
         if iotests.qemu_default_machine != 'pc':
             return

diff --git a/tests/qemu-iotests/041.out b/tests/qemu-iotests/041.out
@@ -1,5 +1,5 @@
-...............................................................................
+.....................................................................................
 ----------------------------------------------------------------------
-Ran 79 tests
+Ran 85 tests
 
 OK