No need to set zeroes for lbas not in use.

Author: Ravi Nagarjun Akella

src/lib/volume/tests/test_volume_io.cpp

@@ -147,8 +147,6 @@ class VolumeIOImpl {
             if(auto it = m_lba_data.find(lba); it != m_lba_data.end()) {
                 data_pattern = it->second;
                 test_common::HBTestHelper::validate_data_buf(buf, m_vol_ptr->info()->page_size, data_pattern);
-            } else {
-                test_common::HBTestHelper::validate_zeros(buf, m_vol_ptr->info()->page_size);
             }
 
             LOGDEBUG("Verify data lba={} pattern expected={} actual={}", lba, data_pattern, *r_cast< uint64_t* >(read_blob.bytes()));

src/lib/volume_mgr.cpp

@@ -274,17 +274,16 @@ VolumeManager::NullAsyncResult HomeBlocksImpl::read(const VolumePtr& vol, const
     for (uint32_t i = 0, blk_count = 0, start_idx = 0; i < out_vector.size(); ++i, ++cur_lba) {
         auto const& [key, value] = out_vector[i];
         // cur_lba is used to keep track of the holes
-        // fill the read buffer with zeroes for the holes
+        // move the read buffer by the size of the holes
         if(cur_lba != key.key()) {
             if(blk_count > 0) {
                 // submit the read for the previous blkids
                 submit_read_to_backend(read_buf, futs, out_vector[start_idx], blk_count, vol, req->part_of_batch);
                 start_idx = i;
                 blk_count = 0;
             }
-            auto fill_size = (key.key() - cur_lba) * vol->rd()->get_blk_size();
-            std::memset(read_buf, 0, fill_size);
-            read_buf += fill_size;
+            auto offset = (key.key() - cur_lba) * vol->rd()->get_blk_size();
+            read_buf += offset;
             cur_lba = key.key();
         }
 
@@ -310,10 +309,6 @@ VolumeManager::NullAsyncResult HomeBlocksImpl::read(const VolumePtr& vol, const
             submit_read_to_backend(read_buf, futs, out_vector[start_idx], 1, vol, req->part_of_batch);
         }
     }
-    // fill the holes at the end of the read buffer
-    if(cur_lba != req->end_lba() + 1) {
-        std::memset(read_buf, 0, (req->end_lba() - cur_lba + 1) * vol->rd()->get_blk_size());
-    }
 
     return out_vector.empty() ? folly::Unit() :
       folly::collectAllUnsafe(futs).thenValue([out_vector = std::move(out_vector), buf = req->buffer