-struct buf swbuf[NSWBUF];
-short swsize[NSWBUF]; /* CAN WE JUST USE B_BCOUNT? */
-int swpf[NSWBUF];
-
-
-#ifdef FASTVAX
-#define notavail(bp) \
-{ \
- int s = spl6(); \
- (bp)->av_back->av_forw = (bp)->av_forw; \
- (bp)->av_forw->av_back = (bp)->av_back; \
- (bp)->b_flags |= B_BUSY; \
- splx(s); \
-}
-#endif
-
-/*
- * Read in (if necessary) the block and return a buffer pointer.
- */
-struct buf *
-bread(dev, blkno)
-dev_t dev;
-daddr_t blkno;
-{
- register struct buf *bp;
-
- bp = getblk(dev, blkno);
- if (bp->b_flags&B_DONE) {
-#ifdef DISKMON
- io_info.ncache++;
-#endif
- return(bp);
- }
- bp->b_flags |= B_READ;
- bp->b_bcount = BSIZE;
- (*bdevsw[major(dev)].d_strategy)(bp);
-#ifdef DISKMON
- io_info.nread++;
-#endif
- u.u_vm.vm_inblk++; /* pay for read */
- iowait(bp);
- return(bp);
-}
-
-/*
- * Read in the block, like bread, but also start I/O on the
- * read-ahead block (which is not allocated to the caller)
- */
-struct buf *
-breada(dev, blkno, rablkno)
-dev_t dev;
-daddr_t blkno, rablkno;
-{
- register struct buf *bp, *rabp;
-
- bp = NULL;
- if (!incore(dev, blkno)) {
- bp = getblk(dev, blkno);
- if ((bp->b_flags&B_DONE) == 0) {
- bp->b_flags |= B_READ;
- bp->b_bcount = BSIZE;
- (*bdevsw[major(dev)].d_strategy)(bp);
-#ifdef DISKMON
- io_info.nread++;
-#endif
- u.u_vm.vm_inblk++; /* pay for read */
- }
- }
- if (rablkno && !incore(dev, rablkno)) {
- rabp = getblk(dev, rablkno);
- if (rabp->b_flags & B_DONE)
- brelse(rabp);
- else {
- rabp->b_flags |= B_READ|B_ASYNC;
- rabp->b_bcount = BSIZE;
- (*bdevsw[major(dev)].d_strategy)(rabp);
-#ifdef DISKMON
- io_info.nreada++;
-#endif
- u.u_vm.vm_inblk++; /* pay in advance */
- }
- }
- if(bp == NULL)
- return(bread(dev, blkno));
- iowait(bp);
- return(bp);
-}
-
-/*
- * Write the buffer, waiting for completion.
- * Then release the buffer.
- */
-bwrite(bp)
-register struct buf *bp;
-{
- register flag;
-
- flag = bp->b_flags;
- bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI | B_AGE);
- bp->b_bcount = BSIZE;
-#ifdef DISKMON
- io_info.nwrite++;
-#endif
- if ((flag&B_DELWRI) == 0)
- u.u_vm.vm_oublk++; /* noone paid yet */
- (*bdevsw[major(bp->b_dev)].d_strategy)(bp);
- if ((flag&B_ASYNC) == 0) {
- iowait(bp);
- brelse(bp);
- } else if (flag & B_DELWRI)
- bp->b_flags |= B_AGE;
- else
- geterror(bp);
-}
-
-/*
- * Release the buffer, marking it so that if it is grabbed
- * for another purpose it will be written out before being
- * given up (e.g. when writing a partial block where it is
- * assumed that another write for the same block will soon follow).
- * This can't be done for magtape, since writes must be done
- * in the same order as requested.
- */
-bdwrite(bp)
-register struct buf *bp;
-{
- register struct buf *dp;
-
- if ((bp->b_flags&B_DELWRI) == 0)
- u.u_vm.vm_oublk++; /* noone paid yet */
- dp = bdevsw[major(bp->b_dev)].d_tab;
- if(dp->b_flags & B_TAPE)
- bawrite(bp);
- else {
- bp->b_flags |= B_DELWRI | B_DONE;
- brelse(bp);
- }
-}
-
-/*
- * Release the buffer, start I/O on it, but don't wait for completion.
- */
-bawrite(bp)
-register struct buf *bp;
-{
-
- bp->b_flags |= B_ASYNC;
- bwrite(bp);
-}
-
-/*
- * release the buffer, with no I/O implied.
- */
-brelse(bp)
-register struct buf *bp;
-{
- register struct buf **backp;
- register s;
-
- if (bp->b_flags&B_WANTED)
- wakeup((caddr_t)bp);
- if (bfreelist.b_flags&B_WANTED) {
- bfreelist.b_flags &= ~B_WANTED;
- wakeup((caddr_t)&bfreelist);
- }
- if ((bp->b_flags&B_ERROR) && bp->b_dev != NODEV) {
- bunhash(bp);
- bp->b_dev = NODEV; /* no assoc. on error */
- }
- s = spl6();
- if(bp->b_flags & (B_AGE|B_ERROR)) {
- backp = &bfreelist.av_forw;
- (*backp)->av_back = bp;
- bp->av_forw = *backp;
- *backp = bp;
- bp->av_back = &bfreelist;
- } else {
- backp = &bfreelist.av_back;
- (*backp)->av_forw = bp;
- bp->av_back = *backp;
- *backp = bp;
- bp->av_forw = &bfreelist;
- }
- bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC|B_AGE);
- splx(s);
-}
-
-/*
- * See if the block is associated with some buffer
- * (mainly to avoid getting hung up on a wait in breada)
- */
-incore(dev, blkno)
-dev_t dev;
-daddr_t blkno;
-{
- register struct buf *bp;
- register int dblkno = fsbtodb(blkno);
-
- for (bp = &buf[bufhash[BUFHASH(blkno)]]; bp != &buf[-1];
- bp = &buf[bp->b_hlink])
- if (bp->b_blkno == dblkno && bp->b_dev == dev)
- return (1);
- return (0);
-}
-
-struct buf *
-baddr(dev, blkno)
-dev_t dev;
-daddr_t blkno;
-{
-
- if (incore(dev, blkno))
- return (bread(dev, blkno));
- return (0);
-}
-
-/*
- * Assign a buffer for the given block. If the appropriate
- * block is already associated, return it; otherwise search
- * for the oldest non-busy buffer and reassign it.
- */
-struct buf *
-getblk(dev, blkno)
-dev_t dev;
-daddr_t blkno;
-{
- register struct buf *bp, *dp, *ep;
- register int i, x;
- register int dblkno = fsbtodb(blkno);
-
- loop:
- (void) spl0();
- for (bp = &buf[bufhash[BUFHASH(blkno)]]; bp != &buf[-1];
- bp = &buf[bp->b_hlink]) {
- if (bp->b_blkno != dblkno || bp->b_dev != dev)
- continue;
- (void) spl6();
- if (bp->b_flags&B_BUSY) {
- bp->b_flags |= B_WANTED;
- sleep((caddr_t)bp, PRIBIO+1);
- goto loop;
- }
- (void) spl0();
-#ifdef DISKMON
- i = 0;
- dp = bp->av_forw;
- while (dp != &bfreelist) {
- i++;
- dp = dp->av_forw;
- }
- if (i<NBUF)
- io_info.bufcount[i]++;
-#endif
- notavail(bp);
- bp->b_flags |= B_CACHE;
- return(bp);
- }
- if (major(dev) >= nblkdev)
- panic("blkdev");
- dp = bdevsw[major(dev)].d_tab;
- if (dp == NULL)
- panic("devtab");
- (void) spl6();
- if (bfreelist.av_forw == &bfreelist) {
- bfreelist.b_flags |= B_WANTED;
- sleep((caddr_t)&bfreelist, PRIBIO+1);
- goto loop;
- }
- spl0();
- bp = bfreelist.av_forw;
- notavail(bp);
- if (bp->b_flags & B_DELWRI) {
- bp->b_flags |= B_ASYNC;
- bwrite(bp);
- goto loop;
- }
- if (bp->b_dev == NODEV)
- goto done;
- /* INLINE EXPANSION OF bunhash(bp) */
- i = BUFHASH(dbtofsb(bp->b_blkno));
- x = bp - buf;
- if (bufhash[i] == x) {
- bufhash[i] = bp->b_hlink;
- } else {
- for (ep = &buf[bufhash[i]]; ep != &buf[-1];
- ep = &buf[ep->b_hlink])
- if (ep->b_hlink == x) {
- ep->b_hlink = bp->b_hlink;
- goto done;
- }
- panic("getblk");
- }
-done:
- /* END INLINE EXPANSION */
- bp->b_flags = B_BUSY;
- bp->b_back->b_forw = bp->b_forw;
- bp->b_forw->b_back = bp->b_back;
- bp->b_forw = dp->b_forw;
- bp->b_back = dp;
- dp->b_forw->b_back = bp;
- dp->b_forw = bp;
- bp->b_dev = dev;
- bp->b_blkno = dblkno;
- i = BUFHASH(blkno);
- bp->b_hlink = bufhash[i];
- bufhash[i] = bp - buf;
- return(bp);
-}
-
-/*
- * get an empty block,
- * not assigned to any particular device
- */
-struct buf *
-geteblk()
-{
- register struct buf *bp, *dp, *ep;
- register int i, x;
-
-loop:
- (void) spl6();
- while (bfreelist.av_forw == &bfreelist) {
- bfreelist.b_flags |= B_WANTED;
- sleep((caddr_t)&bfreelist, PRIBIO+1);
- }
- (void) spl0();
- dp = &bfreelist;
- bp = bfreelist.av_forw;
- notavail(bp);
- if (bp->b_flags & B_DELWRI) {
- bp->b_flags |= B_ASYNC;
- bwrite(bp);
- goto loop;
- }
- if (bp->b_dev != NODEV)
- bunhash(bp);
- bp->b_flags = B_BUSY;
- bp->b_back->b_forw = bp->b_forw;
- bp->b_forw->b_back = bp->b_back;
- bp->b_forw = dp->b_forw;
- bp->b_back = dp;
- dp->b_forw->b_back = bp;
- dp->b_forw = bp;
- bp->b_dev = (dev_t)NODEV;
- bp->b_hlink = -1;
- return(bp);
-}
-
-bunhash(bp)
- register struct buf *bp;
-{
- register struct buf *ep;
- register int i, x;
-
- if (bp->b_dev == NODEV)
- return;
- i = BUFHASH(dbtofsb(bp->b_blkno));
- x = bp - buf;
- if (bufhash[i] == x) {
- bufhash[i] = bp->b_hlink;
- return;
- }
- for (ep = &buf[bufhash[i]]; ep != &buf[-1];
- ep = &buf[ep->b_hlink])
- if (ep->b_hlink == x) {
- ep->b_hlink = bp->b_hlink;
- return;
- }
- panic("bunhash");
-}
-
-/*
- * Wait for I/O completion on the buffer; return errors
- * to the user.
- */
-iowait(bp)
-register struct buf *bp;
-{
-
- (void) spl6();
- while ((bp->b_flags&B_DONE)==0)
- sleep((caddr_t)bp, PRIBIO);
- (void) spl0();
- geterror(bp);
-}
-
-#ifndef FASTVAX
-/*
- * Unlink a buffer from the available list and mark it busy.
- * (internal interface)
- */
-notavail(bp)
-register struct buf *bp;
-{
- register s;
-
- s = spl6();
- bp->av_back->av_forw = bp->av_forw;
- bp->av_forw->av_back = bp->av_back;
- bp->b_flags |= B_BUSY;
- splx(s);
-}
-#endif
-
-/*
- * Mark I/O complete on a buffer. If the header
- * indicates a dirty page push completion, the
- * header is inserted into the ``cleaned'' list
- * to be processed by the pageout daemon. Otherwise
- * release it if I/O is asynchronous, and wake
- * up anyone waiting for it.
- */
-iodone(bp)
-register struct buf *bp;
-{
- register int s;
-
- bp->b_flags |= B_DONE;
- if (bp->b_flags & B_DIRTY) {
- if (bp->b_flags & B_ERROR)
- panic("IO err in push");
- s = spl6();
- cnt.v_pgout++;
- bp->av_forw = bclnlist;
- bp->b_bcount = swsize[bp - swbuf];
- bp->b_pfcent = swpf[bp - swbuf];
- bclnlist = bp;
- if (bswlist.b_flags & B_WANTED)
- wakeup((caddr_t)&proc[2]);
- splx(s);
- }
- if (bp->b_flags&B_ASYNC)
- brelse(bp);
- else {
- bp->b_flags &= ~B_WANTED;
- wakeup((caddr_t)bp);
- }
-}
-
-/*
- * Zero the core associated with a buffer.
- */
-clrbuf(bp)
-struct buf *bp;
-{
- register *p;
- register c;
-
- p = bp->b_un.b_words;
- c = BSIZE/sizeof(int);
- do
- *p++ = 0;
- while (--c);
- bp->b_resid = 0;
-}
projects / unix-history / blobdiff