1. A method for modular block allocation, the method comprising: identifying, by a data storage computing device, one or more dirty buffers to be cleaned in response to a received cleaner message identifying one or more index nodes associated with the dirty buffers, wherein the cleaner message comprises at least one of a specific type of storage medium or a specific location on the storage medium to which data in the dirty buffers is to be written; allocating, by the data storage computing device, one or more volume block numbers (VBNs) of a file system to the dirty buffers, wherein the VBNs correspond to one or more free data blocks of a bucket in a bucket cache; mapping, by the data storage computing device, the VBNs to a stripe set and determining when the stripe set is full; and sending, by the data storage computing device, the stripe set to one or more RAID groups and updating metadata of the file system to indicate that the VBNs allocated to the free data blocks of the bucket have been used, when the determining indicates the stripe set is full.