Method and apparatus for increasing efficiency of data storage in a file system

• US 7,647,355 B2
• Filed: 10/30/2003
• Issued: 01/12/2010
• Est. Priority Date: 10/30/2003
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Best, Steven Francis, Cooper, Michael Richard
• Primary Examiner(s): Lu; Kuen S
• Assistant Examiner(s): HO, BINH VAN
• Application Number:
  US10/697,899
• Publication Number:
  US 20050097142A1
• Time in Patent Office: 2,266 Days
• Field of Search: 707/200
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0674 Disk device

Abstract

A method, apparatus, and computer instructions for storing data in a file system. A determination is made as to whether space is available in an inode of the file in the file system. The data is stored into the inode in response to space being available. Additionally, data for a file may be stored in a block that is partially filled with data from another file. Data for a file may be stored using either the inode or by sharing a block. Data also may be stored using both of these mechanisms.

Claims

1. A computer implemented method comprising:

receiving, using a processor, a command to store a file in a file system having an inode, wherein the inode is usable to store metadata associated with the file;

responsive to the file having a size that is greater than a block size of blocks in the file system, storing a plurality of data of the file only in an integer number of blocks, wherein a first remainder data of the file remains after storing, and wherein the first remainder data is less than the block size;

placing the first remainder data directly into the inode;

responsive to a second remainder data of the file still remaining after the first remainder data is placed into the inode, placing the second remainder data into an unused space of a partially used block of the file system, wherein the partially used block also stores data of another file; and

responsive to the partially used block becoming full from storing the second remainder data in the partially used block, removing the partially used block from a list of free shared blocks, wherein, for each free shared block on the list of free shared blocks, the list of free shared blocks contains a block number, a free byte quantity, and a pointer to a next free shared block.

2. The computer implemented method of claim 1 wherein placing the first remainder data directly into the inode further comprises placing the first remainder data in an extension area of the inode formerly reserved for the metadata, and the computer implemented method further comprises:

updating a mode field in the inode to designate that the first remainder data of the file has been stored in the inode;

prior to performing the step of placing the second remainder data into an unused space of the partially used block of the file system, determining whether the partially used block exists and whether the partially used block has a sufficient free space to store the second remainder data; and

updating the mode field in the inode to designate that the second remainder data has been stored in the partially used block.

3. The computer implemented method of claim 1 further comprising:

when the size is less than the block size, placing data of the file directly into the inode.

4. The computer implemented method of claim 3, further comprising:

when the second remainder data remains after placing the data into the inode, placing the second remainder data into an unused space of a first block of the file system, wherein the first block also stores data of another file, and wherein the first block comprises a last block of the another file.

5. A recordable-type computer readable computer readable medium on which is stored a computer program product executable in a data processing system, the computer program product comprising:

instructions for receiving a command to store a file in a file system having an inode, wherein the inode is usable to store metadata associated with the file;

instructions for, responsive to the file having a size that is greater than a block size of blocks in the file system, storing a plurality of data of the file only in an integer number of blocks, wherein a first remainder data of the file remains after storing, and wherein the first remainder data is less than the block size;

instructions for placing the first remainder data directly into the inode;

instructions for placing a second remainder data into an unused space of a partially used block of the file system responsive to the second remainder data of the file still remaining after the first remainder data is placed into the inode, wherein the partially used block also stores data of another file; and

instructions for removing the partially used block from a list of free shared blocks responsive to the partially used block becoming full from storing the second remainder data in the partially used block, wherein, for each free shared block on the list of free shared blocks, the list of free shared blocks contains a block number, a free byte quantity, and a pointer to a next free shared block.

6. The recordable-type computer readable medium of claim 5 wherein placing the first remainder data directly into the inode further comprises placing the first remainder data in an extension area of the inode formerly reserved for the metadata, and the recordable-type computer readable medium further comprises:

instructions for updating a mode field in the inode to designate that the first remainder data of the file has been stored in the inode;

instructions for, prior to performing the step of placing the second remainder data into an unused space of the partially used block of the file system, determining whether the partially used block exists and whether the partially used block has a sufficient free space to store the second remainder data; and

instructions for updating the mode field in the inode to designate that the second remainder data of the file has been stored in the partially used block.

7. The recordable-type computer readable medium of claim 5, further comprising:

instructions for placing data of the file directly into the inode when the size is less than the block size.

8. A data processing system comprising:

a bus system;

a communications unit connected to the bus system;

a memory connected to the bus system, wherein the memory includes a set of instructions; and

a processing unit connected to the bus system, wherein the processing unit executes the set of instructions comprising;

instructions to receive a command to store a file in a file system having an inode, wherein the inode is usable to store metadata associated with the file;

instructions to store data of the file only in an integer number of blocks responsive to the file having a size that is greater than a block size of blocks in the file system, wherein a first remainder data of the file remains after storing, and wherein the first remainder data is less than the block size;

instructions to place the first remainder data directly into the inode;

instructions to place a second remainder data into an unused space of a partially used block of the file system responsive to the second remainder data of the file still remaining after the first remainder data is placed into the inode, wherein the partially used block also stores data of another file; and

instructions to remove the partially used block from a list of free shared blocks responsive to the partially used block becoming full from storing the second remainder data in the partially used block, wherein, for each free shared block on the list of free shared blocks, the list of free shared blocks contains a block number, a free byte quantity, and a pointer to a next free shared block.

9. The data processing system of claim 8, wherein the instructions to place the first remainder data directly into the inode further comprise instructions to place the first remainder data in an extension area of the inode formerly reserved for the metadata, and the data processing system further comprises:

instructions to update a mode field in the inode to designate that the first remainder data of the file has been stored in the inode;

instructions to determine whether the partially used block exists and whether the partially used block has a sufficient free space to store the second remainder data prior to performing the step of placing the second remainder data into an unused space of the partially used block of the file system;

instructions to update the mode field in the inode to designate that the second remainder data has been stored in the partially used block.