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: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>

diff --git a/block.c b/block.c
index 2dd9262cd00e3da884816fd1f2d6a657830e4b9f..37e72b7a96ff1580ffffbbe0c3987a9158d88921 100644 (file)
--- 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
index 5cc910f567c788f18f5d896179b3a2ba256c672d..c7857c3321362aefe3f95a09d7ae65f103cbf785 100644 (file)
--- 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
index 8583b764a0c83c4941bbe2f047d7e7dfddca7960..c9a6a3ca869b9b394fccc30148c326c7599127eb 100644 (file)
--- 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
index 95b2e2daa5dd10f9e416e829e7b9df2a67f2de74..d2b18ee9df722e08a65a94d83aaa01fd0f76b385 100644 (file)
--- 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
index b3e2674845a09fe987696695922d68e9cb9b2ad3..34770bb33a9d7f144f98d642573cd7e46bd1041a 100644 (file)
--- 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
index 5c6b761d8149cb00c9be688af6a412701c7f2bad..d4f4ea7584a52b15ea63f25dcb7e5c1c162f4bfb 100644 (file)
--- 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
index ff8e2ba0cb963a04a08a06f74ef77a8aa723af0e..006e048975b79d74564aea7631320dd796ccae5b 100644 (file)
--- 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
index 9d381d9b72946d9dd1365869c95e93b98ef7714f..95b7510571dc18853ff83af964c9fe21a896dd51 100755 (executable)
--- 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
index 6d9bee1a4b3cc501c6d6c3954d56289d4becb04a..e20a75ce4f199ef4d6bf46cd23a49f61e5eb8d6b 100644 (file)
--- 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
index 2f5498643462440bfd3d4a8f922969c10e33120e..60f09cc1756965bbf096e614c7e764b921185bbd 100755 (executable)
--- 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
index e30fd3b05bbbbfdb87a1bb54ea3669e5a052ad94..c28b392b87e4b604ea5130b9ed863f18da2d0e84 100644 (file)
--- a/tests/qemu-iotests/041.out
+++ b/tests/qemu-iotests/041.out
@@ -1,5 +1,5 @@
-...............................................................................
+.....................................................................................
 ----------------------------------------------------------------------
-Ran 79 tests
+Ran 85 tests
 
 OK