Merge pull request #7957 from majianpeng/bluestore-read

os/filestore: require offset == length == 0 for full object read; add test

Reviewed-by: Sage Weil <sage@redhat.com>
Reviewed-by: Igor Fedotov <ifedotov@mirantis.com>

src/os/filestore/FileStore.cc

@@ -2973,7 +2973,7 @@ int FileStore::read(
     return r;
   }
 
-  if (len == 0) {
+  if (offset == 0 && len == 0) {
     struct stat st;
     memset(&st, 0, sizeof(struct stat));
     int r = ::fstat(**fd, &st);

src/test/objectstore/store_test.cc

@@ -525,6 +525,17 @@ TEST_P(StoreTest, SimpleObjectTest) {
     in.hexdump(cout);
     ASSERT_TRUE(in.contents_equal(bl));
   }
+  {
+    bufferlist bl;
+    bl.append("abcde01234012340123401234abcde01234012340123401234abcde01234012340123401234abcde01234012340123401234");
+
+    //test: offset=len=0 mean read all data
+    bufferlist in;
+    r = store->read(cid, hoid, 0, 0, in);
+    ASSERT_EQ((int)bl.length(), r);
+    in.hexdump(cout);
+    ASSERT_TRUE(in.contents_equal(bl));
+  }
   {
     ObjectStore::Transaction t;
     t.remove(cid, hoid);