FS_OPENPAGEFILE

Purpose

Creates/opens the paging file for the Pager.

Calling Sequence

int far pascal FS_OPENPAGEFILE(pFlags, pcMaxReq, pName, psffsi, psffsd, usOpenMode, usOpenFlag, usAttr, Reserved) unsigned long far * pFlag; unsigned long far * pcMaxReq; char far * pName; struct sffsi far * psffsi; struct sffsd far * psffsi; unsigned short usOpenMode; unsigned short usOpenFlag; unsigned short usAttr; unsigned long Reserved;

Where

pFlag is a pointer to a flag double word for passing of information between the pager and the file system.

pFlag == 0x00000001	indicates first open of the page file.
pFlag == 0x00004000	indicates physical addresses are required in the page list.
pFlag == 0x00008000	indicates 16:16 virtual addresses are required in the page list.

All other values are reserved.

pcMaxReq is a pointer to a unsigned long where the FSD places the maximum request list length that can be managed by an enhanced strategy device driver.

pName is a pointer to the ASCIIZ path and filename of the paging file.

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.

usOpenMode indicates the desired sharing mode and access mode for the file handle.

See OS/2 Version 2.0 Control Program Programming Reference for a description of the OpenMode parameter for DosOpen.

usOpenFlag indicates the action taken when the file is present or absent.

See OS/2 Version 2.0 Control Program Programming Reference for a description of the usOpenFlag parameter for DosOpen.

usAttr are the OS/2 file attributes.

Reserved is a double word parameter reserved for use in the future.

Remarks

Enough information is provided for the FSD to perform a “normal” open/create call.

Since a page file has special requirements about contiguity of its allocations, FS_OPENPAGEFILE must assure that any data sectors allocated are returned (Create call only). FS_ALLOCATEPAGESPACE will be called to handle file allocation.

If the FSD cannot support the FS_DOPAGEIO (usually due to an disk device driver which does not support the Extended strategy entry point), the FSD can return zero (0) for *pcMaxReq. This tells the kernel file system that it must emulate FS_DOPAGEIO.

The FSD can require either physical or virtual (16:16) addresses for subsequent calls to FS_DOPAGEIO. This allows an FSD to emulate FS_DOPAGEIO without having to worry about dealing with physical addresses.

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