Storage system with decrement protection of reference counts

A method comprising:

• receiving a write input/output (IO) request, the write IO request comprising a data segment smaller than a page granularity of a plurality of storage devices, the plurality of storage devices being configured to store a plurality of data pages, each of the data pages having a content-based signature derived from content of that data page, the content-based signatures of the data pages being associated with physical locations in the plurality of storage devices where the data pages are stored, the plurality of storage devices storing a reference count for each physical location, a given reference count indicating a number of the data pages that map via their respective content-based signatures to the same physical location in the plurality of storage devices;
• in response to receiving the write IO request, determining a content-based signature associated with the data segment, the content-based signature corresponding to a target data page stored at one of the physical locations;
• and
• in response to a decrement request to decrement a reference count of the physical location corresponding to the content-based signature of the target data page, postponing the decrement request,
• wherein the method is implemented by at least one processing device comprising a processor coupled to a memory.

A computer program product comprising a non-transitory processor-readable storage medium having stored therein program code of one or more software programs, wherein the program code when executed by at least one processing device causes said at least one processing device to:

• receive a write input/output (IO) request, the write IO request comprising a data segment smaller than a page granularity of a plurality of storage devices, the plurality of storage devices being configured to store a plurality of data pages, each of the data pages having a content-based signature derived from content of that data page, the content-based signatures of the data pages being associated with physical locations in the plurality of storage devices where the data pages are stored, the plurality of storage devices storing a reference count for each physical location, a given reference count indicating a number of the data pages that map via their respective content-based signatures to the same physical location in the plurality of storage devices;
• in response to receiving the write IO request, determine a content-based signature associated with the data segment, the content-based signature corresponding to a target data page stored at one of the physical locations;
• and
• in response to a decrement request to decrement a reference count of the physical location corresponding to the content-based signature of the target data page, postpone the decrement request.