FS_DOPAGEIO

Purpose

Performs all the I/O operations in a PageCmdList.

Calling Sequence

int far pascal FS_DOPAGEIO(psffsi, psffsd, pList) struct sffsi far * psffsi; struct sffsd far * psffsd; struct PageCmdHeader far * pList;

Where

psffsi is a pointer to the file-system-independent portion of an open file instance.

psffsd is a pointer to the file-system-dependent portion of an open file instance.

pList is a pointer to a PageCmdHeader structure.

The PageCmdHeader structure has the following format:

struct PageCmdHeader { unsigned char InFlags; /* Input Flags */ unsigned char OutFlags; /* Output Flags - must be 0 on entry */ unsigned char OpCount; /* Number of operations */ unsigned char Pad; /* Pad for DWORD alignment */ unsigned long Reserved1; /* Currently Unused */ unsigned long Reserved2; /* Currently Unused */ unsigned long Reserved3; /* Currently Unused */ struct PageCmd PageCmdList; /* Currently Unused */ }

The PageCmd structure has the following format:

struct PageCmd { unsigned char Cmd; /* Cmd Code (Read,Write,Verify) */ unsigned char Priority; /* Same values as for req packets */ unsigned char Status; /* Status byte */ unsigned char Error; /* I24 error code */ unsigned long Addr; /* Physical(0:32) or Virtual(16:16) */ unsigned long FileOffset; /* Byte Offset in page file */ }

Remarks

FS_DOPAGEIO performs all the I/O operations specified in the PageCmdList.

If the disk driver Extended Strategy requests, a request list will be built from the PageCmdList and issued to the driver.

If the disk driver does not support Extended Strategy requests, the FSD can either let the kernel do the emulation (See FS_OPENPAGEFILE to set this state) or has the option to do the emulation itself.

For a detailed description of the Extended Strategy request interface please see the OS/2 Version 2.0 Physical Device Driver Reference.