-/* kern_physio.c 3.2 %H% */
-
-int distrust = 1; /* TEST */
-#include "../h/param.h"
-#include "../h/systm.h"
-#include "../h/dir.h"
-#include "../h/user.h"
-#include "../h/buf.h"
-#include "../h/conf.h"
-#include "../h/proc.h"
-#include "../h/seg.h"
-#include "../h/pte.h"
-#include "../h/vm.h"
-
-/*
- * The following several routines allocate and free
- * buffers with various side effects. In general the
- * arguments to an allocate routine are a device and
- * a block number, and the value is a pointer to
- * to the buffer header; the buffer is marked "busy"
- * so that no one else can touch it. If the block was
- * already in core, no I/O need be done; if it is
- * already busy, the process waits until it becomes free.
- * The following routines allocate a buffer:
- * getblk
- * bread
- * breada
- * baddr (if it is incore)
- * Eventually the buffer must be released, possibly with the
- * side effect of writing it out, by using one of
- * bwrite
- * bdwrite
- * bawrite
- * brelse
- */
-
-#define BUFHSZ 63
-#define BUFHASH(blkno) (blkno % BUFHSZ)
-short bufhash[BUFHSZ];
-
-/*
- * Initialize hash links for buffers.
- */
-bhinit()
-{
- register int i;
-
- for (i = 0; i < BUFHSZ; i++)
- bufhash[i] = -1;
-}
-
-/* #define DISKMON 1 */
-
-#ifdef DISKMON
-struct {
- int nbuf;
- long nread;
- long nreada;
- long ncache;
- long nwrite;
- long bufcount[NBUF];
-} io_info;
-#endif
-
-/*
- * Swap IO headers -
- * They contain the necessary information for the swap I/O.
- * At any given time, a swap header can be in three
- * different lists. When free it is in the free list,
- * when allocated and the I/O queued, it is on the swap
- * device list, and finally, if the operation was a dirty
- * page push, when the I/O completes, it is inserted
- * in a list of cleaned pages to be processed by the pageout daemon.
- */
-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);
-}
-
-/* HASHING IS A GUN LIKE CHANGE, THIS IS THE SAFETY */
-struct buf *
-oincore(dev, blkno)
- dev_t dev;
- daddr_t blkno;
-{
- register struct buf *bp;
- register struct buf *dp;
- register int dblkno = fsbtodb(blkno);
-
- dp = bdevsw[major(dev)].d_tab;
- for (bp=dp->b_forw; bp != dp; bp = bp->b_forw)
- if (bp->b_blkno==dblkno && bp->b_dev==dev &&
- bp >= buf && bp < &buf[NBUF])
- return (bp);
- return ((struct buf *)0);
-}
-
-/*
- * 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) {
- if (distrust)
- if (oincore(dev, blkno) != bp) /* TEST */
- panic("incore 1"); /* TEST */
- return (1);
- }
- if (distrust)
- if (oincore(dev, blkno)) /* TEST */
- panic("incore 2"); /* TEST */
- 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;
- if (distrust)
- if (bp != oincore(dev, blkno)) /* TEST */
- panic("getblk 1"); /* TEST */
- 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 (distrust)
- if (oincore(dev, blkno)) /* TEST */
- panic("getblk 2"); /* TEST */
- 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");
-}
-
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