A memory controller, comprising: a controller memory (411, 413) configured to store a logical-to-physical, L2P, address mapping table (4271, 4273) corresponding to a file; and a controller processor configured to control a memory device, receive a mapping update command, and update the L2P address mapping table (4271, 4273) according to the mapping update command by: replacing original logical addresses of logical block address, LBA, segments of the file with new continuous logical addresses of a merged LBA segment of the file, and changing an original mapping relation between the original logical addresses of the LBA segment of the file and physical addresses of the file, to a new mapping relation between the new continuous logical addresses of the merged LBA segment of the file and the physical addresses of the file; the controller processor is further configured to transmit the updated L2P address mapping table (4271, 4273) to a physical data block of the memory device and transmit an instruction to the host acknowledging that the L2P address mapping table (4271, 4273) has been updated, wherein the controller processor is configured to generate a merge log by recording the new mapping relation between the new continuous logical addresses of the merged LBA segment of the file and the physical addresses of the file and transmit the merge log to the physical data block of the memory device. a controller memory (411, 413) configured to store a logical-to-physical, L2P, address mapping table (4271, 4273) corresponding to a file; and a controller processor configured to control a memory device, receive a mapping update command, and update the L2P address mapping table (4271, 4273) according to the mapping update command by: replacing original logical addresses of logical block address, LBA, segments of the file with new continuous logical addresses of a merged LBA segment of the file, and changing an original mapping relation between the original logical addresses of the LBA segment of the file and physical addresses of the file, to a new mapping relation between the new continuous logical addresses of the merged LBA segment of the file and the physical addresses of the file; the controller processor is further configured to transmit the updated L2P address mapping table (4271, 4273) to a physical data block of the memory device and transmit an instruction to the host acknowledging that the L2P address mapping table (4271, 4273) has been updated, wherein the controller processor is configured to generate a merge log by recording the new mapping relation between the new continuous logical addresses of the merged LBA segment of the file and the physical addresses of the file and transmit the merge log to the physical data block of the memory device. replacing original logical addresses of logical block address, LBA, segments of the file with new continuous logical addresses of a merged LBA segment of the file, and changing an original mapping relation between the original logical addresses of the LBA segment of the file and physical addresses of the file, to a new mapping relation between the new continuous logical addresses of the merged LBA segment of the file and the physical addresses of the file; the controller processor is further configured to transmit the updated L2P address mapping table (4271, 4273) to a physical data block of the memory device and transmit an instruction to the host acknowledging that the L2P address mapping table (4271, 4273) has been updated, wherein the controller processor is configured to generate a merge log by recording the new mapping relation between the new continuous logical addresses of the merged LBA segment of the file and the physical addresses of the file and transmit the merge log to the physical data block of the memory device.