Techniques for compressing a data block involve adding a compression flag to a data block after the data block is decompressed by a protocol layer, the compression flag indicating that the data block is compressible or uncompressible. Such techniques further involve acquiring the compression flag of the data block. Such techniques further involve determining, in response to the compression flag of the data block indicating that the data block is compressible, to perform inline compression on the data block. Such techniques further involve preventing, in response to the compression flag of the data block indicating that the data block is uncompressible, the inline compression from being performed on the data block.