librbd: diff-iterate shouldn't crash on an empty byte range

Commit 0b5ba5fedf70 ("librbd/object_map: add support for ranged
diff-iterate") introduced a regression for the case when whole_object
parameter is set to true.  Despite DiffRequest being called into and
another DiffIterate potentially being spawned recursively, an empty
byte range previously happened to make it.

Bail on an empty byte range early just like we have always done on an
empty snap id range (i.e. when start and end versions are the same).

Fixes: https://tracker.ceph.com/issues/66418
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
(cherry picked from commit a3441a701963fef155fdda7d8f949d73bae26b69)

diff --git a/src/librbd/api/DiffIterate.cc b/src/librbd/api/DiffIterate.cc
index 8d19542b3f3b18cb26e3c4136f46f05f77d825f4..4655f643ba686b2407ec78103535a6acac42e85b 100644 (file)
--- a/src/librbd/api/DiffIterate.cc
+++ b/src/librbd/api/DiffIterate.cc
@@ -312,13 +312,13 @@ int DiffIterate<I>::execute() {
   if (from_snap_id == CEPH_NOSNAP) {
     return -ENOENT;
   }
-  if (from_snap_id == end_snap_id) {
+  if (from_snap_id > end_snap_id) {
+    return -EINVAL;
+  }
+  if (from_snap_id == end_snap_id || m_length == 0) {
     // no diff.
     return 0;
   }
-  if (from_snap_id >= end_snap_id) {
-    return -EINVAL;
-  }
 
   int r;
   bool fast_diff_enabled = false;

diff --git a/src/test/librbd/test_librbd.cc b/src/test/librbd/test_librbd.cc
index f4b4b3907bfe4407f2e3bcc69ed1ad0cc4c3c822..8d138cdec34325ec868368ebd70819ada4786252 100644 (file)
--- a/src/test/librbd/test_librbd.cc
+++ b/src/test/librbd/test_librbd.cc
@@ -7071,23 +7071,59 @@ TYPED_TEST(DiffIterateTest, DiffIterateUnalignedSmall)
   {
     librbd::RBD rbd;
     librbd::Image image;
-    int order = 0;
+    int order = 22;
     std::string name = this->get_temp_image_name();
-    ssize_t size = 10 << 20;
+    ssize_t data_end = 8 << 20;
 
-    ASSERT_EQ(0, create_image_pp(rbd, ioctx, name.c_str(), size, &order));
+    ASSERT_EQ(0, create_image_pp(rbd, ioctx, name.c_str(),
+                                 data_end + (2 << 20), &order));
     ASSERT_EQ(0, rbd.open(ioctx, image, name.c_str(), NULL));
 
     ceph::bufferlist bl;
-    bl.append(std::string(size, '1'));
-    ASSERT_EQ(size, image.write(0, size, bl));
+    bl.append(std::string(data_end, '1'));
+    ASSERT_EQ(data_end, image.write(0, data_end, bl));
 
     std::vector<diff_extent> extents;
+    ASSERT_EQ(0, image.diff_iterate2(NULL, 0, 0, true,
+                                     this->whole_object, vector_iterate_cb,
+                                     &extents));
+    ASSERT_EQ(0u, extents.size());
+
     ASSERT_EQ(0, image.diff_iterate2(NULL, 5000005, 1234, true,
                                      this->whole_object, vector_iterate_cb,
                                      &extents));
     ASSERT_EQ(1u, extents.size());
     ASSERT_EQ(diff_extent(5000005, 1234, true, 0), extents[0]);
+    extents.clear();
+
+    ASSERT_EQ(0, image.diff_iterate2(NULL, data_end - 1, 0, true,
+                                     this->whole_object, vector_iterate_cb,
+                                     &extents));
+    ASSERT_EQ(0u, extents.size());
+
+    ASSERT_EQ(0, image.diff_iterate2(NULL, data_end - 1, 1, true,
+                                     this->whole_object, vector_iterate_cb,
+                                     &extents));
+    ASSERT_EQ(1u, extents.size());
+    ASSERT_EQ(diff_extent(data_end - 1, 1, true, 0), extents[0]);
+    extents.clear();
+
+    ASSERT_EQ(0, image.diff_iterate2(NULL, data_end - 1, 2, true,
+                                     this->whole_object, vector_iterate_cb,
+                                     &extents));
+    ASSERT_EQ(1u, extents.size());
+    ASSERT_EQ(diff_extent(data_end - 1, 1, true, 0), extents[0]);
+    extents.clear();
+
+    ASSERT_EQ(0, image.diff_iterate2(NULL, data_end, 0, true,
+                                     this->whole_object, vector_iterate_cb,
+                                     &extents));
+    ASSERT_EQ(0u, extents.size());
+
+    ASSERT_EQ(0, image.diff_iterate2(NULL, data_end, 1, true,
+                                     this->whole_object, vector_iterate_cb,
+                                     &extents));
+    ASSERT_EQ(0u, extents.size());
 
     ASSERT_PASSED(this->validate_object_map, image);
   }
@@ -7122,6 +7158,20 @@ TYPED_TEST(DiffIterateTest, DiffIterateUnaligned)
     ASSERT_EQ(diff_extent(8376263, 12345, true, 0), extents[0]);
     ASSERT_EQ(diff_extent(8388608, 4194304, true, 0), extents[1]);
     ASSERT_EQ(diff_extent(12582912, 54321, true, 0), extents[2]);
+    extents.clear();
+
+    // length is clipped up to end
+    ASSERT_EQ(0, image.diff_iterate2(NULL, size - 1, size, true,
+                                     this->whole_object, vector_iterate_cb,
+                                     &extents));
+    ASSERT_EQ(1u, extents.size());
+    ASSERT_EQ(diff_extent(size - 1, 1, true, 0), extents[0]);
+    extents.clear();
+
+    // offset past end
+    ASSERT_EQ(-EINVAL, image.diff_iterate2(NULL, size, size, true,
+                                           this->whole_object,
+                                           vector_iterate_cb, &extents));
 
     ASSERT_PASSED(this->validate_object_map, image);
   }