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Annotation of 43BSDReno/sys/hp300/ufs_machdep.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1983, 1988 Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution is only permitted until one year after the first shipment
                      6:  * of 4.4BSD by the Regents.  Otherwise, redistribution and use in source and
                      7:  * binary forms are permitted provided that: (1) source distributions retain
                      8:  * this entire copyright notice and comment, and (2) distributions including
                      9:  * binaries display the following acknowledgement:  This product includes
                     10:  * software developed by the University of California, Berkeley and its
                     11:  * contributors'' in the documentation or other materials provided with the
                     12:  * distribution and in all advertising materials mentioning features or use
                     13:  * of this software.  Neither the name of the University nor the names of
                     14:  * its contributors may be used to endorse or promote products derived from
                     15:  * this software without specific prior written permission.
                     16:  * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
                     17:  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
                     18:  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     19:  *
                     20:  *     @(#)ufs_machdep.c       7.1 (Berkeley) 5/8/90
                     21:  */
                     22: 
                     23: #include "param.h"
                     24: #include "systm.h"
                     25: #include "user.h"
                     26: #include "buf.h"
                     27: #include "conf.h"
                     28: #include "proc.h"
                     29: #include "seg.h"
                     30: #include "vm.h"
                     31: 
                     32: #include "pte.h"
                     33: 
                     34: /*
                     35:  * Machine dependent handling of the buffer cache.
                     36:  */
                     37: 
                     38: /*
                     39:  * Expand or contract the actual memory allocated to a buffer.
                     40:  * If no memory is available, release buffer and take error exit
                     41:  */
                     42: allocbuf(tp, size)
                     43:        register struct buf *tp;
                     44:        int size;
                     45: {
                     46:        register struct buf *bp, *ep;
                     47:        int sizealloc, take, s;
                     48: 
                     49:        sizealloc = roundup(size, CLBYTES);
                     50:        /*
                     51:         * Buffer size does not change
                     52:         */
                     53:        if (sizealloc == tp->b_bufsize)
                     54:                goto out;
                     55:        /*
                     56:         * Buffer size is shrinking.
                     57:         * Place excess space in a buffer header taken from the
                     58:         * BQ_EMPTY buffer list and placed on the "most free" list.
                     59:         * If no extra buffer headers are available, leave the
                     60:         * extra space in the present buffer.
                     61:         */
                     62:        if (sizealloc < tp->b_bufsize) {
                     63:                ep = bfreelist[BQ_EMPTY].av_forw;
                     64:                if (ep == &bfreelist[BQ_EMPTY])
                     65:                        goto out;
                     66:                s = splbio();
                     67:                bremfree(ep);
                     68:                ep->b_flags |= B_BUSY;
                     69:                splx(s);
                     70:                pagemove(tp->b_un.b_addr + sizealloc, ep->b_un.b_addr,
                     71:                    (int)tp->b_bufsize - sizealloc);
                     72:                ep->b_bufsize = tp->b_bufsize - sizealloc;
                     73:                tp->b_bufsize = sizealloc;
                     74:                ep->b_flags |= B_INVAL;
                     75:                ep->b_bcount = 0;
                     76:                brelse(ep);
                     77:                goto out;
                     78:        }
                     79:        /*
                     80:         * More buffer space is needed. Get it out of buffers on
                     81:         * the "most free" list, placing the empty headers on the
                     82:         * BQ_EMPTY buffer header list.
                     83:         */
                     84:        while (tp->b_bufsize < sizealloc) {
                     85:                take = sizealloc - tp->b_bufsize;
                     86:                bp = getnewbuf();
                     87:                if (take >= bp->b_bufsize)
                     88:                        take = bp->b_bufsize;
                     89:                pagemove(&bp->b_un.b_addr[bp->b_bufsize - take],
                     90:                    &tp->b_un.b_addr[tp->b_bufsize], take);
                     91:                tp->b_bufsize += take;
                     92:                bp->b_bufsize = bp->b_bufsize - take;
                     93:                if (bp->b_bcount > bp->b_bufsize)
                     94:                        bp->b_bcount = bp->b_bufsize;
                     95:                if (bp->b_bufsize <= 0) {
                     96:                        bremhash(bp);
                     97:                        binshash(bp, &bfreelist[BQ_EMPTY]);
                     98:                        bp->b_dev = (dev_t)NODEV;
                     99:                        bp->b_error = 0;
                    100:                        bp->b_flags |= B_INVAL;
                    101:                }
                    102:                brelse(bp);
                    103:        }
                    104: out:
                    105:        tp->b_bcount = size;
                    106:        return (1);
                    107: }
                    108: 
                    109: /*
                    110:  * Release space associated with a buffer.
                    111:  */
                    112: bfree(bp)
                    113:        struct buf *bp;
                    114: {
                    115: 
                    116:        bp->b_bcount = 0;
                    117: }

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