Buffered I/O buffers, allocating

The operating system includes a cache of buffers that are used for block I/O transfers. The header structure for these buffers is described on the buf(D4) manual page.

See ``Memory allocation'' for information about allocating memory other than buffer cache buffers in a driver.

DDI functions

The following DDI structures are used for buffered I/O operations:

buf(D4)

Buffer header structure.

bcb(D4)

Breakup control block.

The following DDI functions are used to allocate buffer headers:

bcb_alloc(D3)

Allocate a breakup control block

bcb_prep(D3)

Prepare an allocated breakup control block

bcb_free(D3)

Free a breakup control block

biodone(D3)

Release buffer and unblock processes after a block I/O operation is complete.

bioerror(D3)

Manipulate error fields within a buf(D4) structure.

biowait(D3)

Suspend execution pending completion of a block I/O operation.

biowait_sig(D3)

Suspend execution pending completion of a block I/O operation or a signal.

brelse(D3)

Release buffer

buf_breakup(D3)

buffer breakup routine

clrbuf(D3)

Clear buffer contents

freerbuf(D3)

Release buffer from getrbuf

geteblk(D3)

Allocate 1024 byte buffer, return pointer

geterror(D3)

Return buffer error number

getrbuf(D3)

Allocate buffer header only

ngeteblk(D3)

Allocate n-byte buffer, return pointer

ODDI functions

The following ODDI functions are used to allocate buffer headers:

brelse(D3oddi)

Release buffer.

disksort(D3oddi)

Add a block I/O request to a device's queue.

geteblk(D3oddi)

Get a free buffer from the block buffer pool.

iodone(D3oddi)

Release buffer and unblock processes after a block I/O operation is complete.

iowait(D3oddi)

Suspend execution pending completion of a block I/O operation.

pio_breakup(D3oddi)

Break up a programmed I/O request.