lfiballoc.c

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/* lfiballoc.c - lfiballoc */

#include <xinu.h>

/*------------------------------------------------------------------------
 * lfiballoc  -  Allocate a new index block from free list on disk
 *          (assumes directory mutex held)
 *------------------------------------------------------------------------
 */
ibid32  lfiballoc (void)
{
    ibid32  ibnum;      /* ID of next block on the free list    */
    struct  lfiblk  iblock; /* Buffer to hold an index block    */

    /* Get ID of first index block on free list */

    ibnum = Lf_data.lf_dir.lfd_ifree;
    if (ibnum == LF_INULL) {    /* Ran out of free index blocks */
        panic("out of index blocks");
    }
    lfibget(Lf_data.lf_dskdev, ibnum, &iblock);

    /* Unlink index block from the directory free list */

    Lf_data.lf_dir.lfd_ifree = iblock.ib_next;

    /* Write a copy of the directory to disk after the change */

    write(Lf_data.lf_dskdev, (char *) &Lf_data.lf_dir, LF_AREA_DIR);
    Lf_data.lf_dirdirty = FALSE;

    return ibnum;
}