/* lfdballoc.c - lfdballoc */

#include 

#define  DFILL  '+'             /* Character used to fill an empty block*/

/*------------------------------------------------------------------------
 * lfdballoc  -  Allocate a new data block from free list on disk
 *                      (assumes directory mutex held)
 *------------------------------------------------------------------------
 */
dbid32  lfdballoc (
          struct lfdbfree *dbuff /* Addr. of buffer to hold data block  */
        )
{
        dbid32  dnum;           /* ID of next d-block on the free list  */
        int32   retval;         /* Return value                         */

        /* Get the ID of first data block on the free list */

        dnum = Lf_data.lf_dir.lfd_dfree;
        if (dnum == LF_DNULL) { /* Ran out of free data blocks */
                panic("out of data blocks");
        }
        retval = read(Lf_data.lf_dskdev, (char *)dbuff, dnum);
        if (retval == SYSERR) {
                panic("lfdballoc cannot read disk block\n");
        }

        /* Unlink d-block from in-memory directory */

        Lf_data.lf_dir.lfd_dfree = dbuff->lf_nextdb;
        write(Lf_data.lf_dskdev, (char *)&Lf_data.lf_dir, LF_AREA_DIR);
        Lf_data.lf_dirdirty = FALSE;

        /* Fill data block to erase old data */

        memset((char *)dbuff, DFILL, LF_BLKSIZ);
        return dnum;
}