JPH04219836A - Block control system - Google Patents

Abstract

PURPOSE:To utilize a file resource effectively by effectively assigning free blocks in a block area. CONSTITUTION:When the system is started, a block control initializing means 2 initializes a free block quantity table 6 and a block control table 7. When blocks are secured at a request from a user program 1, a block securing means 3 finds minimum successive free blocks, which satisfy a block quantity requested from the user program, by using the free block quantity table and block control table 7 and passes it to the user program 1. When the blocks are released at a request from the user program 1, a block releasing means 4 releases free blocks before and after the blocks to be released as a series of free blocks by using the free block quantity table 6 and block control table 7 when there are the free blocks before and after the blocks to be released.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a block management method for managing block areas, which are file resources, in a computer system.

0002

2. Description of the Related Art When a user program requires a block to store a file, it requests a block management means to secure the block. Also,
When a block is no longer needed after use, a request is made to the block management means to release the block.

[0003] For ease of management, conventional block management means search for and allocate free space from the block that was last allocated when allocating a block, and also release the block. In some cases, the blocks to be freed were simply left unused.

0004

[Problems to be Solved by the Invention] As mentioned above, in the conventional block management system, blocks that have already been allocated and released are not reused, so the blocks released in the block area are in a state of worm-eaten state. This has the disadvantage that the file resources are not effectively used because the file is left behind and the division loss increases.

The present invention has been proposed in view of the above points, and its purpose is to provide a block management system that can effectively utilize file resources.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides block management initialization means that initializes a free block number table and a block management table at the time of system startup, and When securing a block, a block securing means is provided to obtain the minimum continuous free block that satisfies the number of blocks requested by the user program from a free block count table and a block management table, and to pass it to the user program. A block release means that utilizes a free block number table and a block management table when releasing a block according to a request, and if there are free blocks before and after the block to be released, connects them and releases them as a series of free blocks. I'm trying to prepare.

[0007]

[Operation] In the block management method of the present invention, the block management initialization means initializes the free block number table and the block management table when the system starts, and when allocating blocks according to a request from a user program, When the securing means obtains the minimum continuous free block that satisfies the number of blocks requested by the user program from the free block number table and the block management table, passes it to the user program, and releases the block according to the request from the user program. First, the block release means uses the free block number table and the block management table, and if there are free blocks before and after the block to be released, the free blocks are connected and released as a series of free blocks.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the block management system of the present invention.

In FIG. 1, 1 is a user program 1 that requests the reservation and release of blocks, and 8 is a block area that becomes a file resource. Furthermore, block management initialization means 2, block reservation means 3, block release means 4, and block management termination means 5 are provided as functional units for managing blocks. Further, the free block number table 6 and the block management table 7 are areas for storing information necessary for management.

FIG. 2 shows a concrete example of the free block number table 6 and the block management table 7.

In FIG. 2, the free block number table 6
has the same number of entries as the number of blocks in the block area 8, and each entry has items for the number of free blocks and the number of the first free block.

The block management table 7 also has the same number of entries as the number of blocks in the block area 8, and each entry has items such as a block number, the number of free blocks, a BEFORE chain block number, a NEXT chain block number, and a block address. are doing.

[0014] When there are, for example, n consecutive free blocks in the block area 8, the entry in the block management table 7 corresponding to the first block number of the free blocks is changed to the free block where the number of free blocks is n. Empty blocks are managed by chaining to entries in the block number table 6. Note that n is an integer greater than or equal to 1 and less than or equal to the maximum number of blocks MAX.

For example, in FIG. 2, block number 2
, 4, 7 to 8, 10 to 13, and 21 to 256 are empty, but block numbers 2 and 4, in which there is one consecutive empty block, are entries with the number of empty blocks of 1 in the empty block number table 6. The first block number 7 with two consecutive free blocks is chained to the entry with two free blocks in the free block number table 6, and the first block number 10 with four consecutive free blocks is The number of free blocks in the number of free blocks table 6 is chained to the entry with the number of free blocks being 4, and the first block number 21 having 236 consecutive free blocks is chained to the entry with the number of free blocks of 236 in the number of free blocks table 6.

The functions of other parts will be explained through the following operations to avoid duplication.

The operation of the above embodiment will now be explained in different cases.

(1) Table Initialization Process The block management initialization means 2 is activated once by some trigger when the system is started, and initializes the free block number table 6 and the block management table 7.

Specifically, in the free block number table 6, the number of free blocks for each entry is set in ascending order from 1 to the maximum block number MAX, and 0 is set as the first free block number.

[0020] Also, the number of free blocks is the maximum number of blocks M
The first empty block number of the entry AX is set to 1.

Regarding the block management table 7, the block number of each entry is set in ascending order from 1 to the maximum block number MAX, and the maximum block number MAX is set as the number of free blocks for the entry with block number 1. , the other block numbers are set to 0, the BEFORE chain block number and the NEXT chain block number are set to 0, and the block address is set to the address of each block in the block area 8.

(2) Block reservation processing When the user program 1 needs a block to store a file, the block reservation means 3
Specify the required number of blocks for a request to reserve consecutive blocks.

[0023] The block securing means 3 searches the free block count table 6 and selects free blocks among the entries that have the number of free blocks equal to or greater than the number of blocks requested by the user program 1 and whose first free block number is not 0. Find the entry with the smallest number.

Next, the entry in the block management table 7 pointed to by the first free block number in that entry is removed from the chain from the free block number table 6, and the first block number of the block pointed to by the block address in that entry is removed. is passed to user program 1.

[0025] At this time, if the number of free blocks in the entry removed from the chain is larger than the number of blocks requested by the user program 1, the block removed from the chain will remain, so the remaining first block number will be The corresponding entry in the block management table 7 is chained to the entry in the free block number table 6 whose number of free blocks is equal to the number of remaining blocks.

FIG. 3 shows an HC diagram showing the above process in more detail.
P chart (hierarchical and co
-mpact description chart
). Note that a free block number table counter and work are used as the data area for work.

(3) Block release processing When a block is no longer needed in the user program 1, it requests the block release means 4 to release the block by specifying the block number to be released and the number of blocks to be released. .

The block release means 4 finds an entry in the block management table 7 corresponding to the block number to be released, and if the entry immediately before that entry is free,
The entry of the block to be released is chained to the previous entry, and the same process is repeated for the entry immediately before the first entry in the free area until an entry in use is found.

Furthermore, the entry in the block management table 7 corresponding to the last block to be released is obtained, and if the entry immediately after that entry is free, the entry immediately after it is removed from the chain of the free block count table 6. Chaining is performed to the entry corresponding to the last block to be released, and the same process is repeated for the entry immediately after the last entry in the free area until an entry in use is found.

The number of consecutive free blocks is set in the first entry of the finally obtained continuous free blocks, and the entry in the free block number table 6 having the same number of free blocks as that number is set. Chain.

FIG. 4 shows an HC diagram showing the above process in more detail.
This is a P chart.

(4) Termination process When terminating block management, block management termination means 5
performs predetermined termination processing such as saving the free block count table 6 and the block management table 7.

[0033]

[Effects of the Invention] As explained above, in the block management method of the present invention, when securing a block, the minimum free block that satisfies the number of blocks requested by the user program is sought and the user is notified. When transferring and releasing a block, if there are free blocks before and after the block to be released, the free blocks before and after the block to be released are connected and released as a continuous free block area. By reducing the chances of the area being left moth-eaten, and by keeping the division loss to a minimum,
This has the effect that file resources can be used effectively.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of a block management method of the present invention.

FIG. 2 is an explanatory diagram of a free block number table and a block management table.

FIG. 3 is an HCP chart showing details of block reservation processing.

FIG. 4 is an HCP chart showing details of block release processing.

[Explanation of symbols]

1...User program 2...Block management initialization means 3...Means for securing blocks 4...Block release means 5... Block management termination means 6...Free block number table 7...Block management table 8...Block area

Claims (2)

[Claims] Claim 1: Block management initialization means that initializes a free block number table and a block management table at the time of system startup, and a block number requested by the user program when securing blocks according to a request from the user program. block securing means for finding the minimum continuous free block satisfying the above criteria from a free block number table and a block management table and passing it to a user program;
When releasing a block according to a request from a user program, the free block count table and block management table are used, and if there are free blocks before and after the block to be released, they are linked and released as a series of free blocks. A block management method characterized by comprising block release means. [Claim 2] The free block number table has an entry having the number of free blocks and the first free block number as items, and the block management table has entries including the block number, the number of free blocks, the BEFORE chain block number, and the NEXT
2. The block management system according to claim 1, further comprising an entry having a chain block number and a block address as items.