Granted Patent B2

US 8,407,401 · App. 12/324,099 · Granted Mar 26, 2013

Abstract

Claims (47)

1. A method comprising:

receiving, at a controller embodied on a block-based mass memory, an erase command from a host device in communication with the mass memory such that the host device has ability to read from and write to the mass memory and is configured to free one or more blocks of the mass memory by writing to memory allocation data stored in the mass memory prior to sending the erase command to the controller, wherein the erase command comprises a location of a block storing memory allocation data for one or more blocks of the mass memory, an indication of a size of an entry in the memory allocation data, an indication of a value of an entry denoting that a corresponding block is free, an indication of a number of entries in the memory allocation data, an indication of a location of a block in the mass memory corresponding to the first entry in the memory allocation data, and an indication of a size of a block in the mass memory;

accessing the block storing memory allocation data based at least in part upon the location included in the erase command;

determining, based at least in part upon the memory allocation data, at least one block within the mass memory that has been freed by the host device; and

erasing the at least one freed block in response to the erase command.

2. A method according to claim 1 , wherein the host device has direct read and write access to the mass memory.

3. A method according to claim 1 , wherein erasing the freed blocks comprises securely erasing the freed blocks so that data erased from the freed blocks cannot be restored.

4. A method according to claim 1 , wherein:

receiving an erase command comprises receiving an erase command for each file system partition on the mass memory;

accessing the block storing memory allocation data comprises accessing the memory allocation data for each file system partition;

determining blocks within the mass memory that have been freed by the host device comprises determining blocks within each file system partition on the mass memory that have been freed by the host device; and

erasing the freed blocks comprises erasing the freed blocks in each file system partition.

5. A method according to claim 1 , wherein the location of the block storing memory allocation data for one or more blocks of the mass memory further comprises a location of a block storing data comprising a free/allocated status of one or more blocks of the mass memory.

6. A method according to claim 1 , wherein the mass memory comprises a flash memory.

7. A computer program product comprising at least one non-transitory computer-readable storage medium having computer-readable program instructions stored therein, the computer-readable program instructions comprising:

a program instruction for receiving, at a controller embodied on a block-based mass memory, an erase command from a host device in communication with the mass memory such that the host device has ability to read from and write to the mass memory and is configured to free one or more blocks of the mass memory by writing to memory allocation data stored in the mass memory prior to sending the erase command to the controller, wherein the erase command comprises a location of a block storing memory allocation data for one or more blocks of the mass memory, an indication of a size of an entry in the memory allocation data, an indication of a value of an entry denoting that a corresponding block is free, an indication of a number of entries in the memory allocation data, an indication of a location of a block in the mass memory corresponding to the first entry in the memory allocation data, and an indication of a size of a block in the mass memory;

a program instruction for accessing the block storing memory allocation data based at least in part upon the location included in the erase command;

a program instruction for determining, based at least in part upon the memory allocation data, at least one block within the mass memory that has been freed by the host device; and

a program instruction for erasing the at least one freed block in response to the erase command.

8. A computer program product according to claim 7 , wherein the host device has direct read and write access to the mass memory.

9. A computer program product according to claim 7 , wherein the program instruction for erasing the freed blocks comprises instructions for securely erasing the freed blocks so that data erased from the freed blocks cannot be restored.

10. A computer program product according to claim 7 , wherein:

the program instruction for receiving an erase command comprises instructions for receiving an erase command for each file system partition on the mass memory;

the program instruction for accessing the block storing memory allocation data comprises instructions for accessing the memory allocation data for each file system partition;

the program instruction for determining blocks within the mass memory that have been freed by the host device comprises instructions for determining blocks within each file system partition on the mass memory that have been freed by the host device; and

the program instruction for erasing the freed blocks comprises instructions for erasing the freed blocks in each file system partition.

11. A computer program product according to claim 7 , wherein the location of the block storing memory allocation data for one or more blocks of the mass memory further comprises a location of a block storing data comprising a free/allocated status of one or more blocks of the mass memory.

12. A computer program product according to claim 7 , wherein the mass memory comprises a flash memory.

13. An apparatus comprising a block-based mass memory and a controller, wherein the controller is configured to:

receive an erase command from a host device in communication with the mass memory such that the host device has ability to read from and write to the mass memory and is configured to free one or more blocks of the mass memory by writing to memory allocation data stored in the mass memory prior to sending the erase command to the controller, wherein the erase command comprises a location of a block storing memory allocation data for one or more blocks of the mass memory, an indication of a size of an entry in the memory allocation data, an indication of a value of an entry denoting that a corresponding block is free, an indication of a number of entries in the memory allocation data, an indication of a location of a block in the mass memory corresponding to the first entry in the memory allocation data, and an indication of a size of a block in the mass memory;

access the block storing memory allocation data based at least in part upon the location included in the erase command;

determine, based at least in part upon the memory allocation data, at least one block within the mass memory that has been freed by the host device; and

erase the at least one freed block in response to the erase command.

14. The apparatus of claim 13 , wherein the host device has direct read and write access to the mass memory.

15. The apparatus of claim 13 , wherein the controller is configured to erase the freed blocks by securely erasing the freed blocks so that data erased from the freed blocks cannot be restored.

16. The apparatus of claim 13 , wherein the controller is configured to:

receive an erase command by receiving an erase command for each file system partition on the mass memory;

access the block storing memory allocation data by accessing the memory allocation data for each file system partition;

determine blocks within the mass memory that have been freed by the host device by determining blocks within each file system partition on the mass memory that have been freed by the host device; and

erase the freed blocks by erasing the freed blocks in each file system partition.

17. The apparatus of claim 13 , wherein the location of the block storing memory allocation data for one or more blocks of the mass memory further comprises a location of a block storing data comprising a free/allocated status of one or more blocks of the mass memory.

18. The apparatus of claim 13 , wherein the mass memory comprises a flash memory.

19. An apparatus comprising:

means for receiving, at a controller embodied on a block-based mass memory, an erase command from a host device in communication with the memory such that the host device has ability to read from and write to the memory and is configured to free one or more blocks of the mass memory by writing to memory allocation data stored in the mass memory prior to sending the erase command to the controller, wherein the erase command comprises a location of a block storing memory allocation data for one or more blocks of the mass memory, an indication of a size of an entry in the memory allocation data, an indication of a value of an entry denoting that a corresponding block is free, an indication of a number of entries in the memory allocation data, an indication of a location of a block in the mass memory corresponding to the first entry in the memory allocation data, and an indication of a size of a block in the mass memory;

means for accessing the block storing memory allocation data based at least in part upon the location included in the erase command;

means for determining, based at least in part upon the memory allocation data, at least one block within the mass memory that has been freed by the host device; and

means for erasing the at least one freed block in response to the erase command.

Assignments (10)