Relocating compressed extents using batch-hole list

A data storage system, comprising control circuitry that includes a set of processing units coupled to memory, the control circuitry constructed and arranged to:

• aggregate a set of data received in I/O (Input/Output) requests into a batch of data, the batch of data including multiple extents, each extent directed to a respective logical address in a file system running in the data storage system;
• compress a current extent of the batch of data to produce a compressed extent, the current extent directed to a logical address that is already backed by a fragment in the data storage system, such that a write of the compressed extent is an overwrite;
• and
• perform a batch-relocate operation, the batch-relocate operation (i) obtaining a set of mapping metadata that maps all of the extents in the batch of data, (ii) creating a batch-hole list that identifies a set of holes pointed to by the set of mapping metadata, each hole representing a range of storage that contains no currently-valid data, and (iii) placing the compressed extent into one of the holes identified in the batch-hole list,
• wherein the control circuitry is further constructed and arranged to select a hole in the batch-hole list that is minimally large enough to accommodate the compressed extent.

A computer program product including a set of non-transitory, computer-readable media having instructions which, when executed by control circuitry of a data storage system, cause the control circuitry to perform a method of writing data, the method comprising:

• aggregating a set of data received in I/O (Input/Output) requests into a batch of data, the batch of data including multiple extents, each extent directed to a respective logical address in a file system running in the data storage system;
• compressing a current extent of the batch of data to produce a compressed extent, the current extent directed to a logical address that is already backed by a fragment in the data storage system, such that a write of the compressed extent is an overwrite;
• and
• performing a batch-relocate operation, the batch-relocate operation (i) obtaining a set of mapping metadata that maps all of the extents in the batch of data, (ii) creating a batch-hole list that identifies a set of holes pointed to by the set of mapping metadata, each hole representing a range of storage that contains no currently-valid data, and (iii) placing the compressed extent into one of the holes identified in the batch-hole list,
• wherein the relocate operation further includes selecting a hole in the batch-hole list that is minimally large enough to accommodate the compressed extent, and wherein the act of placing the compressed extent places the compressed extent into the selected hole.