Functional Specification

This section describes the data structure, external interfaces of the component and briefly identifies the consumers of these interfaces.

Data structures

I/O FOMs use the following data structure:

The Bulk I/O Service is required to maintain run-time context of I/O FOMs. The data structure m0_io_fom_cob_rw maintain required context data.

Pointer to generic FOM structure
This holds the information about generic FOM (e.g. its generic states, type, locality, reply FOP, file operation log etc.)
Total number of descriptor for bulk data transfer requested.
Current network buffer descriptor index
Current index vector list index
Batch size for bulk I/O processing.
Actual data transferd.
STOB identifier
Storage object identifier which tells the actual device on which I/O operation intended.
List of STOB operation vector
This holds the information required for async STOB I/O (e.g. data segments, operations, channel to signal on completion etc.)
List acquired network buffers pointer
zero-copy fills this buffers in bulk I/O case.

Interfaces

Bulk I/O Service will be implemented as read FOM and write FOM. Since request handler processes FOM, each FOM needs to define its operations:

Bulk I/O FOM type operations:

m0_io_fom_cob_rw_create()    Request handler uses this interface to
                             create I/O FOM.

Bulk I/O FOM operations :

m0_io_fom_cob_rw_locality_get()   Request handler uses this interface to
                                  get the locality for this I/O FOM.
m0_io_fom_cob_rw_tick()           Request handler uses this interface to
                                  execute next phase of I/O FOM.
m0_io_fom_cob_rw_fini()           Request handler uses this interface after
                                  I/O FOM finishes its execution.

Bulk I/O Service type operations :

m0_io_service_init()       This interface will be called by request handler
                           to create & initiate Bulk I/O Service.

Bulk I/O Service operations :

m0_io_service_start()      This interface will be called by request handler
                           to start Buk I/O Service.

m0_io_service_stop()       This interface will be called by request handler
                           to stop Buk I/O Service.

m0_io_service_fini()       This interface will be called by request handler
                           to finish & de-allocate Bulk I/O Service.

Bulk I/O FOM creation & initialization

On receiving of bulk I/O FOP, FOM is created & initialized for respective FOP type. Then it is placed into FOM processing queue.