BlockInputStream#readChunkFromContainer() reads the whole chunk from disk even if we need to read only a part of the chunk.
This Jira aims to improve readChunkFromContainer so that only that part of the chunk file is read which is needed by client plus the part of chunk file which is required to verify the checksum.
For example, lets say the client is reading from index 120 to 450 in the chunk. And let's say checksum is stored for every 100 bytes in the chunk i.e. the first checksum is for bytes from index 0 to 99, the next for bytes from index 100 to 199 and so on. To verify bytes from 120 to 450, we would need to read from bytes 100 to 499 so that checksum verification can be done.