==== FS_DOPAGEIO ====

**Purpose**

Performs all the I/O operations in a PageCmdList.   

**Calling Sequence**

<code c>
int far pascal FS_DOPAGEIO(psffsi, psffsd, pList)

struct sffsi far * psffsi;
struct sffsd far * psffsd;
struct PageCmdHeader far * pList;
</code>

**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:   

<code c>
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                   */
}
</code>

The //PageCmd// structure has the following format:   

<code c>
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  */
}
</code>

**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.