rdsclose.c

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/* rdsclose.c - rdsclose */

#include <xinu.h>

/*------------------------------------------------------------------------
 * rdsclose  -  Close a remote disk device
 *------------------------------------------------------------------------
 */
devcall rdsclose (
      struct dentry *devptr     /* Entry in device switch table */
    )
{
    struct  rdscblk *rdptr;     /* Ptr to control block entry   */
    struct  rdbuff  *bptr;      /* Ptr to buffer on a list  */
    struct  rdbuff  *nptr;      /* Ptr to next buff on the list */
    int32   nmoved;         /* Number of buffers moved  */

    /* Device must be open */

    rdptr = &rdstab[devptr->dvminor];
    if (rdptr->rd_state != RD_OPEN) {
        return SYSERR;
    }

    /* Request queue must be empty */

    if (rdptr->rd_rhnext != (struct rdbuff *)&rdptr->rd_rtnext) {
        return SYSERR;
    }

    /* Move all buffers from the cache to the free list */

    bptr = rdptr->rd_chnext;
    nmoved = 0;
    while (bptr != (struct rdbuff *)&rdptr->rd_ctnext) {
        nmoved++;

        /* Unlink buffer from cache */

        nptr = bptr->rd_next;
        (bptr->rd_prev)->rd_next = nptr;
        nptr->rd_prev = bptr->rd_prev;

        /* Insert buffer into free list */

        bptr->rd_next = rdptr->rd_free;
    
        rdptr->rd_free = bptr;
        bptr->rd_status = RD_INVALID;

        /* Move to next buffer in the cache */

        bptr = nptr;
    }

    /* Set the state to indicate the device is closed */

    rdptr->rd_state = RD_FREE;
    return OK;
}