590 lines
15 KiB
C
590 lines
15 KiB
C
/*
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* Copyright (c) 1989, 1990, 1991, 1992 William F. Jolitz, TeleMuse
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This software is a component of "386BSD" developed by
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* William F. Jolitz, TeleMuse.
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* 4. Neither the name of the developer nor the name "386BSD"
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS A COMPONENT OF 386BSD DEVELOPED BY WILLIAM F. JOLITZ
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* AND IS INTENDED FOR RESEARCH AND EDUCATIONAL PURPOSES ONLY. THIS
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* SOFTWARE SHOULD NOT BE CONSIDERED TO BE A COMMERCIAL PRODUCT.
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* THE DEVELOPER URGES THAT USERS WHO REQUIRE A COMMERCIAL PRODUCT
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* NOT MAKE USE THIS WORK.
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*
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* FOR USERS WHO WISH TO UNDERSTAND THE 386BSD SYSTEM DEVELOPED
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* BY WILLIAM F. JOLITZ, WE RECOMMEND THE USER STUDY WRITTEN
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* REFERENCES SUCH AS THE "PORTING UNIX TO THE 386" SERIES
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* (BEGINNING JANUARY 1991 "DR. DOBBS JOURNAL", USA AND BEGINNING
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* JUNE 1991 "UNIX MAGAZIN", GERMANY) BY WILLIAM F. JOLITZ AND
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* LYNNE GREER JOLITZ, AS WELL AS OTHER BOOKS ON UNIX AND THE
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* ON-LINE 386BSD USER MANUAL BEFORE USE. A BOOK DISCUSSING THE INTERNALS
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* OF 386BSD ENTITLED "386BSD FROM THE INSIDE OUT" WILL BE AVAILABLE LATE 1992.
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*
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPER ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE DEVELOPER BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: vfs__bio.c,v 1.3 1993/05/18 15:38:35 cgd Exp $
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*/
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#include "param.h"
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#include "proc.h"
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#include "vnode.h"
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#include "buf.h"
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#include "specdev.h"
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#include "mount.h"
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#include "malloc.h"
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#include "vm/vm.h"
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#include "resourcevar.h"
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struct buf *getnewbuf(int);
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extern vm_map_t buffer_map;
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/*
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* Initialize buffer headers and related structures.
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*/
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void bufinit()
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{
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struct bufhd *bh;
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struct buf *bp;
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/* first, make a null hash table */
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for(bh = bufhash; bh < bufhash + BUFHSZ; bh++) {
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bh->b_flags = 0;
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bh->b_forw = (struct buf *)bh;
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bh->b_back = (struct buf *)bh;
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}
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/* next, make a null set of free lists */
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for(bp = bfreelist; bp < bfreelist + BQUEUES; bp++) {
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bp->b_flags = 0;
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bp->av_forw = bp;
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bp->av_back = bp;
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bp->b_forw = bp;
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bp->b_back = bp;
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}
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/* finally, initialize each buffer header and stick on empty q */
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for(bp = buf; bp < buf + nbuf ; bp++) {
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bp->b_flags = B_HEAD | B_INVAL; /* we're just an empty header */
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bp->b_dev = NODEV;
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bp->b_vp = 0;
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binstailfree(bp, bfreelist + BQ_EMPTY);
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binshash(bp, bfreelist + BQ_EMPTY);
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}
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}
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/*
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* Find the block in the buffer pool.
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* If the buffer is not present, allocate a new buffer and load
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* its contents according to the filesystem fill routine.
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*/
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int
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bread(struct vnode *vp, daddr_t blkno, int size, struct ucred *cred,
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struct buf **bpp)
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{
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struct buf *bp;
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int rv = 0;
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bp = getblk (vp, blkno, size);
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/* if not found in cache, do some I/O */
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if ((bp->b_flags & B_CACHE) == 0 || (bp->b_flags & B_INVAL) != 0) {
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bp->b_flags |= B_READ;
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bp->b_flags &= ~(B_DONE|B_ERROR|B_INVAL);
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if (cred != NOCRED) crhold(cred); /* 25 Apr 92*/
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bp->b_rcred = cred;
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VOP_STRATEGY(bp);
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rv = biowait (bp);
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}
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*bpp = bp;
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return (rv);
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}
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/*
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* Operates like bread, but also starts I/O on the specified
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* read-ahead block. [See page 55 of Bach's Book]
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*/
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int
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breada(struct vnode *vp, daddr_t blkno, int size, daddr_t rablkno, int rabsize,
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struct ucred *cred, struct buf **bpp)
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{
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struct buf *bp, *rabp;
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int rv = 0, needwait = 0;
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bp = getblk (vp, blkno, size);
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/* if not found in cache, do some I/O */
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if ((bp->b_flags & B_CACHE) == 0 || (bp->b_flags & B_INVAL) != 0) {
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bp->b_flags |= B_READ;
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bp->b_flags &= ~(B_DONE|B_ERROR|B_INVAL);
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if (cred != NOCRED) crhold(cred); /* 25 Apr 92*/
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bp->b_rcred = cred;
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VOP_STRATEGY(bp);
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needwait++;
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}
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rabp = getblk (vp, rablkno, rabsize);
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/* if not found in cache, do some I/O (overlapped with first) */
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if ((rabp->b_flags & B_CACHE) == 0 || (rabp->b_flags & B_INVAL) != 0) {
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rabp->b_flags |= B_READ | B_ASYNC;
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rabp->b_flags &= ~(B_DONE|B_ERROR|B_INVAL);
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if (cred != NOCRED) crhold(cred); /* 25 Apr 92*/
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rabp->b_rcred = cred;
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VOP_STRATEGY(rabp);
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} else
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brelse(rabp);
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/* wait for original I/O */
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if (needwait)
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rv = biowait (bp);
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*bpp = bp;
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return (rv);
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}
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/*
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* Synchronous write.
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* Release buffer on completion.
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*/
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int
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bwrite(register struct buf *bp)
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{
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int rv;
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if(bp->b_flags & B_INVAL) {
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brelse(bp);
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return (0);
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} else {
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int wasdelayed;
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if(!(bp->b_flags & B_BUSY))
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panic("bwrite: not busy");
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wasdelayed = bp->b_flags & B_DELWRI;
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bp->b_flags &= ~(B_READ|B_DONE|B_ERROR|B_ASYNC|B_DELWRI);
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if(wasdelayed)
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reassignbuf(bp, bp->b_vp);
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bp->b_flags |= B_DIRTY;
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bp->b_vp->v_numoutput++;
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VOP_STRATEGY(bp);
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rv = biowait(bp);
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brelse(bp);
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return (rv);
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}
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}
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/*
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* Delayed write.
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*
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* The buffer is marked dirty, but is not queued for I/O.
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* This routine should be used when the buffer is expected
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* to be modified again soon, typically a small write that
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* partially fills a buffer.
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*
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* NB: magnetic tapes cannot be delayed; they must be
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* written in the order that the writes are requested.
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*/
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void
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bdwrite(register struct buf *bp)
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{
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if(!(bp->b_flags & B_BUSY))
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panic("bdwrite: not busy");
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if(bp->b_flags & B_INVAL) {
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brelse(bp);
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}
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if(bp->b_flags & B_TAPE) {
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bwrite(bp);
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return;
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}
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bp->b_flags &= ~(B_READ|B_DONE);
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bp->b_flags |= B_DIRTY|B_DELWRI;
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reassignbuf(bp, bp->b_vp);
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brelse(bp);
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return;
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}
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/*
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* Asynchronous write.
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* Start I/O on a buffer, but do not wait for it to complete.
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* The buffer is released when the I/O completes.
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*/
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void
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bawrite(register struct buf *bp)
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{
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if(!(bp->b_flags & B_BUSY))
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panic("bawrite: not busy");
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if(bp->b_flags & B_INVAL)
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brelse(bp);
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else {
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int wasdelayed;
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wasdelayed = bp->b_flags & B_DELWRI;
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bp->b_flags &= ~(B_READ|B_DONE|B_ERROR|B_DELWRI);
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if(wasdelayed)
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reassignbuf(bp, bp->b_vp);
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bp->b_flags |= B_DIRTY | B_ASYNC;
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bp->b_vp->v_numoutput++;
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VOP_STRATEGY(bp);
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}
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}
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/*
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* Release a buffer.
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* Even if the buffer is dirty, no I/O is started.
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*/
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void
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brelse(register struct buf *bp)
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{
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int x;
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/* anyone need a "free" block? */
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x=splbio();
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if ((bfreelist + BQ_AGE)->b_flags & B_WANTED) {
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(bfreelist + BQ_AGE) ->b_flags &= ~B_WANTED;
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wakeup(bfreelist);
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}
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/* anyone need this very block? */
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if (bp->b_flags & B_WANTED) {
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bp->b_flags &= ~B_WANTED;
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wakeup(bp);
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}
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if (bp->b_flags & (B_INVAL|B_ERROR)) {
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bp->b_flags |= B_INVAL;
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bp->b_flags &= ~(B_DELWRI|B_CACHE);
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if(bp->b_vp)
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brelvp(bp);
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}
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/* enqueue */
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/* just an empty buffer head ... */
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/*if(bp->b_flags & B_HEAD)
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binsheadfree(bp, bfreelist + BQ_EMPTY)*/
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/* buffers with junk contents */
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/*else*/ if(bp->b_flags & (B_ERROR|B_INVAL|B_NOCACHE))
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binsheadfree(bp, bfreelist + BQ_AGE)
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/* buffers with stale but valid contents */
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else if(bp->b_flags & B_AGE)
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binstailfree(bp, bfreelist + BQ_AGE)
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/* buffers with valid and quite potentially reuseable contents */
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else
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binstailfree(bp, bfreelist + BQ_LRU)
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/* unlock */
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bp->b_flags &= ~B_BUSY;
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splx(x);
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}
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int freebufspace;
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int allocbufspace;
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/*
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* Find a buffer which is available for use.
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* If free memory for buffer space and an empty header from the empty list,
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* use that. Otherwise, select something from a free list.
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* Preference is to AGE list, then LRU list.
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*/
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static struct buf *
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getnewbuf(int sz)
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{
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struct buf *bp;
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int x;
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x = splbio();
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start:
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/* can we constitute a new buffer? */
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if (freebufspace > sz
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&& bfreelist[BQ_EMPTY].av_forw != (struct buf *)bfreelist+BQ_EMPTY) {
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caddr_t addr;
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/*#define notyet*/
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#ifndef notyet
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if ((addr = malloc (sz, M_TEMP, M_WAITOK)) == 0) goto tryfree;
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#else /* notyet */
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/* get new memory buffer */
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if (round_page(sz) == sz)
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addr = (caddr_t) kmem_alloc_wired_wait(buffer_map, sz);
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else
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addr = (caddr_t) malloc (sz, M_TEMP, M_WAITOK);
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/*if ((addr = malloc (sz, M_TEMP, M_NOWAIT)) == 0) goto tryfree;*/
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bzero(addr, sz);
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#endif /* notyet */
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freebufspace -= sz;
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allocbufspace += sz;
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bp = bfreelist[BQ_EMPTY].av_forw;
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bp->b_flags = B_BUSY | B_INVAL;
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bremfree(bp);
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bp->b_un.b_addr = addr;
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bp->b_bufsize = sz; /* 20 Aug 92*/
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goto fillin;
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}
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tryfree:
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if (bfreelist[BQ_AGE].av_forw != (struct buf *)bfreelist+BQ_AGE) {
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bp = bfreelist[BQ_AGE].av_forw;
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bremfree(bp);
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} else if (bfreelist[BQ_LRU].av_forw != (struct buf *)bfreelist+BQ_LRU) {
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bp = bfreelist[BQ_LRU].av_forw;
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bremfree(bp);
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} else {
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/* wait for a free buffer of any kind */
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(bfreelist + BQ_AGE)->b_flags |= B_WANTED;
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sleep(bfreelist, PRIBIO);
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splx(x);
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return (0);
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}
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/* if we are a delayed write, convert to an async write! */
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if (bp->b_flags & B_DELWRI) {
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bp->b_flags |= B_BUSY;
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bawrite (bp);
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goto start;
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}
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if(bp->b_vp)
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brelvp(bp);
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/* we are not free, nor do we contain interesting data */
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if (bp->b_rcred != NOCRED) crfree(bp->b_rcred); /* 25 Apr 92*/
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if (bp->b_wcred != NOCRED) crfree(bp->b_wcred);
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bp->b_flags = B_BUSY;
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fillin:
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bremhash(bp);
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splx(x);
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bp->b_dev = NODEV;
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bp->b_vp = NULL;
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bp->b_blkno = bp->b_lblkno = 0;
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bp->b_iodone = 0;
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bp->b_error = 0;
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bp->b_wcred = bp->b_rcred = NOCRED;
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if (bp->b_bufsize != sz)
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allocbuf(bp, sz);
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bp->b_bcount = bp->b_bufsize = sz;
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bp->b_dirtyoff = bp->b_dirtyend = 0;
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return (bp);
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}
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/*
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* Check to see if a block is currently memory resident.
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*/
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struct buf *
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incore(struct vnode *vp, daddr_t blkno)
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{
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struct buf *bh;
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struct buf *bp;
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bh = BUFHASH(vp, blkno);
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/* Search hash chain */
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bp = bh->b_forw;
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while (bp != (struct buf *) bh) {
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/* hit */
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if (bp->b_lblkno == blkno && bp->b_vp == vp
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&& (bp->b_flags & B_INVAL) == 0)
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return (bp);
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bp = bp->b_forw;
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}
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return(0);
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}
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/*
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* Get a block of requested size that is associated with
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* a given vnode and block offset. If it is found in the
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* block cache, mark it as having been found, make it busy
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* and return it. Otherwise, return an empty block of the
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* correct size. It is up to the caller to insure that the
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* cached blocks be of the correct size.
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*/
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struct buf *
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getblk(register struct vnode *vp, daddr_t blkno, int size)
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{
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struct buf *bp, *bh;
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int x;
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for (;;) {
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if (bp = incore(vp, blkno)) {
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x = splbio();
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if (bp->b_flags & B_BUSY) {
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bp->b_flags |= B_WANTED;
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sleep (bp, PRIBIO);
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splx(x);
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continue;
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}
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bp->b_flags |= B_BUSY | B_CACHE;
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bremfree(bp);
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if (size > bp->b_bufsize)
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panic("now what do we do?");
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/* if (bp->b_bufsize != size) allocbuf(bp, size); */
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} else {
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if((bp = getnewbuf(size)) == 0) continue;
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bp->b_blkno = bp->b_lblkno = blkno;
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bgetvp(vp, bp);
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x = splbio();
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bh = BUFHASH(vp, blkno);
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binshash(bp, bh);
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bp->b_flags = B_BUSY;
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}
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splx(x);
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return (bp);
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}
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}
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/*
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* Get an empty, disassociated buffer of given size.
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*/
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struct buf *
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geteblk(int size)
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{
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struct buf *bp;
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int x;
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while ((bp = getnewbuf(size)) == 0)
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;
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x = splbio();
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binshash(bp, bfreelist + BQ_AGE);
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splx(x);
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return (bp);
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}
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/*
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* Exchange a buffer's underlying buffer storage for one of different
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* size, taking care to maintain contents appropriately. When buffer
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* increases in size, caller is responsible for filling out additional
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* contents. When buffer shrinks in size, data is lost, so caller must
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* first return it to backing store before shrinking the buffer, as
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* no implied I/O will be done.
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*
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* Expanded buffer is returned as value.
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*/
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void
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allocbuf(register struct buf *bp, int size)
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{
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caddr_t newcontents;
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/* get new memory buffer */
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#ifndef notyet
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newcontents = (caddr_t) malloc (size, M_TEMP, M_WAITOK);
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#else /* notyet */
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if (round_page(size) == size)
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newcontents = (caddr_t) kmem_alloc_wired_wait(buffer_map, size);
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else
|
|
newcontents = (caddr_t) malloc (size, M_TEMP, M_WAITOK);
|
|
#endif /* notyet */
|
|
|
|
/* copy the old into the new, up to the maximum that will fit */
|
|
bcopy (bp->b_un.b_addr, newcontents, min(bp->b_bufsize, size));
|
|
|
|
/* return old contents to free heap */
|
|
#ifndef notyet
|
|
free (bp->b_un.b_addr, M_TEMP);
|
|
#else /* notyet */
|
|
if (round_page(bp->b_bufsize) == bp->b_bufsize)
|
|
kmem_free_wakeup(buffer_map, bp->b_un.b_addr, bp->b_bufsize);
|
|
else
|
|
free (bp->b_un.b_addr, M_TEMP);
|
|
#endif /* notyet */
|
|
|
|
/* adjust buffer cache's idea of memory allocated to buffer contents */
|
|
freebufspace -= size - bp->b_bufsize;
|
|
allocbufspace += size - bp->b_bufsize;
|
|
|
|
/* update buffer header */
|
|
bp->b_un.b_addr = newcontents;
|
|
bp->b_bcount = bp->b_bufsize = size;
|
|
}
|
|
|
|
/*
|
|
* Patiently await operations to complete on this buffer.
|
|
* When they do, extract error value and return it.
|
|
* Extract and return any errors associated with the I/O.
|
|
* If an invalid block, force it off the lookup hash chains.
|
|
*/
|
|
int
|
|
biowait(register struct buf *bp)
|
|
{
|
|
int x;
|
|
|
|
x = splbio();
|
|
while ((bp->b_flags & B_DONE) == 0)
|
|
sleep((caddr_t)bp, PRIBIO);
|
|
if((bp->b_flags & B_ERROR) || bp->b_error) {
|
|
if ((bp->b_flags & B_INVAL) == 0) {
|
|
bp->b_flags |= B_INVAL;
|
|
bremhash(bp);
|
|
binshash(bp, bfreelist + BQ_AGE);
|
|
}
|
|
if (!bp->b_error)
|
|
bp->b_error = EIO;
|
|
else
|
|
bp->b_flags |= B_ERROR;
|
|
splx(x);
|
|
return (bp->b_error);
|
|
} else {
|
|
splx(x);
|
|
return (0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Finish up operations on a buffer, calling an optional
|
|
* function (if requested), and releasing the buffer if
|
|
* marked asynchronous. Then mark this buffer done so that
|
|
* others biowait()'ing for it will notice when they are
|
|
* woken up from sleep().
|
|
*/
|
|
int
|
|
biodone(register struct buf *bp)
|
|
{
|
|
int x;
|
|
|
|
x = splbio();
|
|
if (bp->b_flags & B_CALL) (*bp->b_iodone)(bp);
|
|
bp->b_flags &= ~B_CALL;
|
|
if ((bp->b_flags & (B_READ|B_DIRTY)) == B_DIRTY) {
|
|
bp->b_flags &= ~B_DIRTY;
|
|
vwakeup(bp);
|
|
}
|
|
if (bp->b_flags & B_ASYNC)
|
|
brelse(bp);
|
|
bp->b_flags &= ~B_ASYNC;
|
|
bp->b_flags |= B_DONE;
|
|
wakeup(bp);
|
|
splx(x);
|
|
}
|