typo

[unix-history] / usr / src / sys / kern / vfs_cluster.c

diff --git a/usr/src/sys/kern/vfs_cluster.c b/usr/src/sys/kern/vfs_cluster.c
index 55770f8..4f74f8f 100644 (file)
--- a/usr/src/sys/kern/vfs_cluster.c
+++ b/usr/src/sys/kern/vfs_cluster.c
@@ -1,120 +1,61 @@
-/*     vfs_cluster.c   4.30    82/05/22        */
-
-/* merged into kernel:  @(#)bio.c 2.3 4/8/82 */
-
-#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"
-#include "../h/trace.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
- */
-
-struct buf bfreelist[BQUEUES];
-struct buf bswlist, *bclnlist;
-
-#define        BUFHSZ  63
-#define RND    (MAXBSIZE/DEV_BSIZE)
-struct bufhd bufhash[BUFHSZ];
-#define        BUFHASH(dev, dblkno)    \
-       ((struct buf *)&bufhash[((int)(dev)+(((int)(dblkno))/RND)) % BUFHSZ])
-

 /*
 /*

- * Initialize hash links for buffers.
+ * Copyright (c) 1982, 1986 Regents of the University of California.
+ * All rights reserved.  The Berkeley software License Agreement
+ * specifies the terms and conditions for redistribution.
+ *
+ *     @(#)vfs_cluster.c       7.3 (Berkeley) %G%

  */
  */

-bhinit()
-{
-       register int i;
-       register struct bufhd *bp;

 
 

-       for (bp = bufhash, i = 0; i < BUFHSZ; i++, bp++)
-               bp->b_forw = bp->b_back = (struct buf *)bp;
-}
+#include "../machine/pte.h"

 
 

-/* #define     DISKMON 1 */
-
-#ifdef DISKMON
-struct {
-       int     nbuf;
-       long    nread;
-       long    nreada;
-       long    ncache;
-       long    nwrite;
-       long    bufcount[64];
-} io_info;
-#endif
-
-/*
-
-#ifndef        UNFAST
-#define        notavail(bp) \
-{ \
-       int x = spl6(); \
-       (bp)->av_back->av_forw = (bp)->av_forw; \
-       (bp)->av_forw->av_back = (bp)->av_back; \
-       (bp)->b_flags |= B_BUSY; \
-       splx(x); \
-}
-#endif
+#include "param.h"
+#include "systm.h"
+#include "dir.h"
+#include "user.h"
+#include "buf.h"
+#include "conf.h"
+#include "proc.h"
+#include "seg.h"
+#include "vm.h"
+#include "trace.h"

 
 /*
  * Read in (if necessary) the block and return a buffer pointer.
  */
 struct buf *
 
 /*
  * Read in (if necessary) the block and return a buffer pointer.
  */
 struct buf *

+#ifdef SECSIZE
+bread(dev, blkno, size, secsize)
+#else SECSIZE

 bread(dev, blkno, size)
 bread(dev, blkno, size)

+#endif SECSIZE

        dev_t dev;
        daddr_t blkno;
        int size;
        dev_t dev;
        daddr_t blkno;
        int size;

+#ifdef SECSIZE
+       long secsize;
+#endif SECSIZE

 {
        register struct buf *bp;
 
 {
        register struct buf *bp;
 

+       if (size == 0)
+               panic("bread: size 0");
+#ifdef SECSIZE
+       bp = getblk(dev, blkno, size, secsize);
+#else SECSIZE

        bp = getblk(dev, blkno, size);
        bp = getblk(dev, blkno, size);

-       if (bp->b_flags&B_DONE) {
-#ifdef TRACE
-               trace(TR_BREADHIT, dev, blkno);
-#endif
-#ifdef DISKMON
-               io_info.ncache++;
-#endif
-               return(bp);
+#endif SECSIZE
+       if (bp->b_flags&(B_DONE|B_DELWRI)) {
+               trace(TR_BREADHIT, pack(dev, size), blkno);
+               return (bp);

        }
        bp->b_flags |= B_READ;
        }
        bp->b_flags |= B_READ;

+       if (bp->b_bcount > bp->b_bufsize)
+               panic("bread");

        (*bdevsw[major(dev)].d_strategy)(bp);
        (*bdevsw[major(dev)].d_strategy)(bp);

-#ifdef TRACE
-       trace(TR_BREADMISS, dev, blkno);
-#endif
-#ifdef DISKMON
-       io_info.nread++;
-#endif
-       u.u_vm.vm_inblk++;              /* pay for read */
-       iowait(bp);
-       return(bp);
+       trace(TR_BREADMISS, pack(dev, size), blkno);
+       u.u_ru.ru_inblock++;            /* pay for read */
+       biowait(bp);
+       return (bp);

 }
 
 /*
 }
 
 /*


@@ -122,55 +63,79 @@ bread(dev, blkno, size)
  * read-ahead block (which is not allocated to the caller)
  */
 struct buf *
  * read-ahead block (which is not allocated to the caller)
  */
 struct buf *

-breada(dev, blkno, rablkno, size)
+#ifdef SECSIZE
+breada(dev, blkno, size, secsize, rablkno, rabsize)
+#else SECSIZE
+breada(dev, blkno, size, rablkno, rabsize)
+#endif SECSIZE

        dev_t dev;
        dev_t dev;

-       daddr_t blkno, rablkno;
-       int size;
+       daddr_t blkno; int size;
+#ifdef SECSIZE
+       long secsize;
+#endif SECSIZE
+       daddr_t rablkno; int rabsize;

 {
        register struct buf *bp, *rabp;
 
        bp = NULL;
 {
        register struct buf *bp, *rabp;
 
        bp = NULL;

+       /*
+        * If the block isn't in core, then allocate
+        * a buffer and initiate i/o (getblk checks
+        * for a cache hit).
+        */

        if (!incore(dev, blkno)) {
        if (!incore(dev, blkno)) {

+#ifdef SECSIZE
+               bp = getblk(dev, blkno, size, secsize);
+#else SECSIZE

                bp = getblk(dev, blkno, size);
                bp = getblk(dev, blkno, size);

-               if ((bp->b_flags&B_DONE) == 0) {
+#endif SECSIZE
+               if ((bp->b_flags&(B_DONE|B_DELWRI)) == 0) {

                        bp->b_flags |= B_READ;
                        bp->b_flags |= B_READ;

+                       if (bp->b_bcount > bp->b_bufsize)
+                               panic("breada");

                        (*bdevsw[major(dev)].d_strategy)(bp);
                        (*bdevsw[major(dev)].d_strategy)(bp);

-#ifdef TRACE
-                       trace(TR_BREADMISS, dev, blkno);
-#endif
-#ifdef DISKMON
-                       io_info.nread++;
-#endif
-                       u.u_vm.vm_inblk++;              /* pay for read */
-               }
-#ifdef TRACE
-               else
-                       trace(TR_BREADHIT, dev, blkno);
-#endif
+                       trace(TR_BREADMISS, pack(dev, size), blkno);
+                       u.u_ru.ru_inblock++;            /* pay for read */
+               } else
+                       trace(TR_BREADHIT, pack(dev, size), blkno);

        }
        }

+
+       /*
+        * If there's a read-ahead block, start i/o
+        * on it also (as above).
+        */

        if (rablkno && !incore(dev, rablkno)) {
        if (rablkno && !incore(dev, rablkno)) {

-               rabp = getblk(dev, rablkno, size);
-               if (rabp->b_flags & B_DONE) {
+#ifdef SECSIZE
+               rabp = getblk(dev, rablkno, rabsize, secsize);
+#else SECSIZE
+               rabp = getblk(dev, rablkno, rabsize);
+#endif SECSIZE
+               if (rabp->b_flags & (B_DONE|B_DELWRI)) {

                        brelse(rabp);
                        brelse(rabp);

-#ifdef TRACE
-                       trace(TR_BREADHITRA, dev, blkno);
-#endif
+                       trace(TR_BREADHITRA, pack(dev, rabsize), blkno);

                } else {
                        rabp->b_flags |= B_READ|B_ASYNC;
                } else {
                        rabp->b_flags |= B_READ|B_ASYNC;

+                       if (rabp->b_bcount > rabp->b_bufsize)
+                               panic("breadrabp");

                        (*bdevsw[major(dev)].d_strategy)(rabp);
                        (*bdevsw[major(dev)].d_strategy)(rabp);

-#ifdef TRACE
-                       trace(TR_BREADMISSRA, dev, rablock);
-#endif
-#ifdef DISKMON
-                       io_info.nreada++;
-#endif
-                       u.u_vm.vm_inblk++;              /* pay in advance */
+                       trace(TR_BREADMISSRA, pack(dev, rabsize), rablock);
+                       u.u_ru.ru_inblock++;            /* pay in advance */

                }
        }
                }
        }

-       if(bp == NULL)
-               return(bread(dev, blkno, size));
-       iowait(bp);
-       return(bp);
+
+       /*
+        * If block was in core, let bread get it.
+        * If block wasn't in core, then the read was started
+        * above, and just wait for it.
+        */
+       if (bp == NULL)
+#ifdef SECSIZE
+               return (bread(dev, blkno, size, secsize));
+#else SECSIZE
+               return (bread(dev, blkno, size));
+#endif SECSIZE
+       biowait(bp);
+       return (bp);

 }
 
 /*
 }
 
 /*


@@ -178,28 +143,29 @@ breada(dev, blkno, rablkno, size)
  * Then release the buffer.
  */
 bwrite(bp)
  * Then release the buffer.
  */
 bwrite(bp)

-register struct buf *bp;
+       register struct buf *bp;

 {
        register flag;
 
        flag = bp->b_flags;
 {
        register flag;
 
        flag = bp->b_flags;

-       bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI | B_AGE);
-#ifdef DISKMON
-       io_info.nwrite++;
-#endif
+       bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);

        if ((flag&B_DELWRI) == 0)
        if ((flag&B_DELWRI) == 0)

-               u.u_vm.vm_oublk++;              /* noone paid yet */
-#ifdef TRACE
-       trace(TR_BWRITE, bp->b_dev, bp->b_blkno);
-#endif
+               u.u_ru.ru_oublock++;            /* noone paid yet */
+       trace(TR_BWRITE, pack(bp->b_dev, bp->b_bcount), bp->b_blkno);
+       if (bp->b_bcount > bp->b_bufsize)
+               panic("bwrite");

        (*bdevsw[major(bp->b_dev)].d_strategy)(bp);
        (*bdevsw[major(bp->b_dev)].d_strategy)(bp);

+
+       /*
+        * If the write was synchronous, then await i/o completion.
+        * If the write was "delayed", then we put the buffer on
+        * the q of blocks awaiting i/o completion status.
+        */

        if ((flag&B_ASYNC) == 0) {
        if ((flag&B_ASYNC) == 0) {

-               iowait(bp);
+               biowait(bp);

                brelse(bp);
        } else if (flag & B_DELWRI)
                bp->b_flags |= B_AGE;
                brelse(bp);
        } else if (flag & B_DELWRI)
                bp->b_flags |= B_AGE;

-       else
-               geterror(bp);

 }
 
 /*
 }
 
 /*


@@ -211,14 +177,12 @@ register struct buf *bp;
  * in the same order as requested.
  */
 bdwrite(bp)
  * in the same order as requested.
  */
 bdwrite(bp)

-register struct buf *bp;
+       register struct buf *bp;

 {
 {

-       register int flags;

 
        if ((bp->b_flags&B_DELWRI) == 0)
 
        if ((bp->b_flags&B_DELWRI) == 0)

-               u.u_vm.vm_oublk++;              /* noone paid yet */
-       flags = bdevsw[major(bp->b_dev)].d_flags;
-       if(flags & B_TAPE)
+               u.u_ru.ru_oublock++;            /* noone paid yet */
+       if (bdevsw[major(bp->b_dev)].d_flags & B_TAPE)

                bawrite(bp);
        else {
                bp->b_flags |= B_DELWRI | B_DONE;
                bawrite(bp);
        else {
                bp->b_flags |= B_DELWRI | B_DONE;


@@ -230,7 +194,7 @@ register struct buf *bp;
  * Release the buffer, start I/O on it, but don't wait for completion.
  */
 bawrite(bp)
  * Release the buffer, start I/O on it, but don't wait for completion.
  */
 bawrite(bp)

-register struct buf *bp;
+       register struct buf *bp;

 {
 
        bp->b_flags |= B_ASYNC;
 {
 
        bp->b_flags |= B_ASYNC;


@@ -238,14 +202,19 @@ register struct buf *bp;
 }
 
 /*
 }
 
 /*

- * release the buffer, with no I/O implied.
+ * Release the buffer, with no I/O implied.

  */
 brelse(bp)
  */
 brelse(bp)

-register struct buf *bp;
+       register struct buf *bp;

 {
        register struct buf *flist;
        register s;
 
 {
        register struct buf *flist;
        register s;
 

+       trace(TR_BRELSE, pack(bp->b_dev, bp->b_bufsize), bp->b_blkno);
+       /*
+        * If someone's waiting for the buffer, or
+        * is waiting for a buffer wake 'em up.
+        */

        if (bp->b_flags&B_WANTED)
                wakeup((caddr_t)bp);
        if (bfreelist[0].b_flags&B_WANTED) {
        if (bp->b_flags&B_WANTED)
                wakeup((caddr_t)bp);
        if (bfreelist[0].b_flags&B_WANTED) {


@@ -257,14 +226,19 @@ register struct buf *bp;
                        bp->b_flags &= ~B_ERROR;        /* try again later */
                else
                        bp->b_dev = NODEV;              /* no assoc */
                        bp->b_flags &= ~B_ERROR;        /* try again later */
                else
                        bp->b_dev = NODEV;              /* no assoc */

-       s = spl6();
-       if (bp->b_flags & (B_ERROR|B_INVAL)) {
+
+       /*
+        * Stick the buffer back on a free list.
+        */
+       s = splbio();
+       if (bp->b_bufsize <= 0) {
+               /* block has no buffer ... put at front of unused buffer list */
+               flist = &bfreelist[BQ_EMPTY];
+               binsheadfree(bp, flist);
+       } else if (bp->b_flags & (B_ERROR|B_INVAL)) {

                /* block has no info ... put at front of most free list */
                /* block has no info ... put at front of most free list */

-               flist = &bfreelist[BQUEUES-1];
-               flist->av_forw->av_back = bp;
-               bp->av_forw = flist->av_forw;
-               flist->av_forw = bp;
-               bp->av_back = flist;
+               flist = &bfreelist[BQ_AGE];
+               binsheadfree(bp, flist);

        } else {
                if (bp->b_flags & B_LOCKED)
                        flist = &bfreelist[BQ_LOCKED];
        } else {
                if (bp->b_flags & B_LOCKED)
                        flist = &bfreelist[BQ_LOCKED];


@@ -272,10 +246,7 @@ register struct buf *bp;
                        flist = &bfreelist[BQ_AGE];
                else
                        flist = &bfreelist[BQ_LRU];
                        flist = &bfreelist[BQ_AGE];
                else
                        flist = &bfreelist[BQ_LRU];

-               flist->av_back->av_forw = bp;
-               bp->av_back = flist->av_back;
-               flist->av_back = bp;
-               bp->av_forw = flist;
+               binstailfree(bp, flist);

        }
        bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC|B_AGE);
        splx(s);
        }
        bp->b_flags &= ~(B_WANTED|B_BUSY|B_ASYNC|B_AGE);
        splx(s);


@@ -286,8 +257,8 @@ register struct buf *bp;
  * (mainly to avoid getting hung up on a wait in breada)
  */
 incore(dev, blkno)
  * (mainly to avoid getting hung up on a wait in breada)
  */
 incore(dev, blkno)

-dev_t dev;
-daddr_t blkno;
+       dev_t dev;
+       daddr_t blkno;

 {
        register struct buf *bp;
        register struct buf *dp;
 {
        register struct buf *bp;
        register struct buf *dp;


@@ -295,20 +266,31 @@ daddr_t blkno;
        dp = BUFHASH(dev, blkno);
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
                if (bp->b_blkno == blkno && bp->b_dev == dev &&
        dp = BUFHASH(dev, blkno);
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
                if (bp->b_blkno == blkno && bp->b_dev == dev &&

-                   !(bp->b_flags & B_INVAL))
+                   (bp->b_flags & B_INVAL) == 0)

                        return (1);
        return (0);
 }
 
 struct buf *
                        return (1);
        return (0);
 }
 
 struct buf *

+#ifdef SECSIZE
+baddr(dev, blkno, size, secsize)
+#else SECSIZE

 baddr(dev, blkno, size)
 baddr(dev, blkno, size)

+#endif SECSIZE

        dev_t dev;
        daddr_t blkno;
        int size;
        dev_t dev;
        daddr_t blkno;
        int size;

+#ifdef SECSIZE
+       long secsize;
+#endif SECSIZE

 {
 
        if (incore(dev, blkno))
 {
 
        if (incore(dev, blkno))

+#ifdef SECSIZE
+               return (bread(dev, blkno, size, secsize));
+#else SECSIZE

                return (bread(dev, blkno, size));
                return (bread(dev, blkno, size));

+#endif SECSIZE

        return (0);
 }
 
        return (0);
 }
 


@@ -317,31 +299,57 @@ baddr(dev, blkno, size)
  * block is already associated, return it; otherwise search
  * for the oldest non-busy buffer and reassign it.
  *
  * block is already associated, return it; otherwise search
  * for the oldest non-busy buffer and reassign it.
  *

+ * If we find the buffer, but it is dirty (marked DELWRI) and
+ * its size is changing, we must write it out first. When the
+ * buffer is shrinking, the write is done by brealloc to avoid
+ * losing the unwritten data. When the buffer is growing, the
+ * write is done by getblk, so that bread will not read stale
+ * disk data over the modified data in the buffer.
+ *

  * We use splx here because this routine may be called
  * on the interrupt stack during a dump, and we don't
  * want to lower the ipl back to 0.
  */
 struct buf *
  * We use splx here because this routine may be called
  * on the interrupt stack during a dump, and we don't
  * want to lower the ipl back to 0.
  */
 struct buf *

+#ifdef SECSIZE
+getblk(dev, blkno, size, secsize)
+#else SECSIZE

 getblk(dev, blkno, size)
 getblk(dev, blkno, size)

+#endif SECSIZE

        dev_t dev;
        daddr_t blkno;
        int size;
        dev_t dev;
        daddr_t blkno;
        int size;

+#ifdef SECSIZE
+       long secsize;
+#endif SECSIZE

 {
 {

-       register struct buf *bp, *dp, *ep;
-#ifdef DISKMON
-       register int i;
-#endif
+       register struct buf *bp, *dp;

        int s;
 
        int s;
 

-       if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-PGSHIFT))
-               blkno = 1 << ((sizeof(int)*NBBY-PGSHIFT) + 1);
+       if (size > MAXBSIZE)
+               panic("getblk: size too big");
+       /*
+        * To prevent overflow of 32-bit ints when converting block
+        * numbers to byte offsets, blknos > 2^32 / DEV_BSIZE are set
+        * to the maximum number that can be converted to a byte offset
+        * without overflow. This is historic code; what bug it fixed,
+        * or whether it is still a reasonable thing to do is open to
+        * dispute. mkm 9/85
+        */
+       if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-DEV_BSHIFT))
+               blkno = 1 << ((sizeof(int)*NBBY-DEV_BSHIFT) + 1);
+       /*
+        * Search the cache for the block.  If we hit, but
+        * the buffer is in use for i/o, then we wait until
+        * the i/o has completed.
+        */

        dp = BUFHASH(dev, blkno);
        dp = BUFHASH(dev, blkno);

-    loop:
+loop:

        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
                if (bp->b_blkno != blkno || bp->b_dev != dev ||
                    bp->b_flags&B_INVAL)
                        continue;
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
                if (bp->b_blkno != blkno || bp->b_dev != dev ||
                    bp->b_flags&B_INVAL)
                        continue;

-               s = spl6();
+               s = splbio();

                if (bp->b_flags&B_BUSY) {
                        bp->b_flags |= B_WANTED;
                        sleep((caddr_t)bp, PRIBIO+1);
                if (bp->b_flags&B_BUSY) {
                        bp->b_flags |= B_WANTED;
                        sleep((caddr_t)bp, PRIBIO+1);


@@ -349,56 +357,36 @@ getblk(dev, blkno, size)
                        goto loop;
                }
                splx(s);
                        goto loop;
                }
                splx(s);

-#ifdef DISKMON
-               i = 0;
-               dp = bp->av_forw;
-               while ((dp->b_flags & B_HEAD) == 0) {
-                       i++;
-                       dp = dp->av_forw;
-               }
-               if (i<64)
-                       io_info.bufcount[i]++;
-#endif

                notavail(bp);
                notavail(bp);

-               brealloc(bp, size);
+               if (bp->b_bcount != size) {
+                       if (bp->b_bcount < size && (bp->b_flags&B_DELWRI)) {
+                               bp->b_flags &= ~B_ASYNC;
+                               bwrite(bp);
+                               goto loop;
+                       }
+                       if (brealloc(bp, size) == 0)
+                               goto loop;
+               }
+               if (bp->b_bcount != size && brealloc(bp, size) == 0)
+                       goto loop;

                bp->b_flags |= B_CACHE;
                bp->b_flags |= B_CACHE;

-               return(bp);
+               return (bp);

        }
        if (major(dev) >= nblkdev)
                panic("blkdev");
        }
        if (major(dev) >= nblkdev)
                panic("blkdev");

-       s = spl6();
-       for (ep = &bfreelist[BQUEUES-1]; ep > bfreelist; ep--)
-               if (ep->av_forw != ep)
-                       break;
-       if (ep == bfreelist) {          /* no free blocks at all */
-               ep->b_flags |= B_WANTED;
-               sleep((caddr_t)ep, PRIBIO+1);
-               splx(s);
-               goto loop;
-       }
-       splx(s);
-       bp = ep->av_forw;
-       notavail(bp);
-       if (bp->b_flags & B_DELWRI) {
-               bp->b_flags |= B_ASYNC;
-               bwrite(bp);
-               goto loop;
-       }
-#ifdef TRACE
-       trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
-#endif
-       bp->b_flags = B_BUSY;
+       bp = getnewbuf();

        bfree(bp);
        bfree(bp);

-       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;
+       bremhash(bp);
+       binshash(bp, dp);

        bp->b_dev = dev;
        bp->b_dev = dev;

+#ifdef SECSIZE
+       bp->b_blksize = secsize;
+#endif SECSIZE

        bp->b_blkno = blkno;
        bp->b_blkno = blkno;

-       brealloc(bp, size);
-       return(bp);
+       bp->b_error = 0;
+       if (brealloc(bp, size) == 0)
+               goto loop;
+       return (bp);

 }
 
 /*
 }
 
 /*


@@ -409,44 +397,30 @@ struct buf *
 geteblk(size)
        int size;
 {
 geteblk(size)
        int size;
 {

-       register struct buf *bp, *dp;
-       int s;
+       register struct buf *bp, *flist;

 
 

+       if (size > MAXBSIZE)
+               panic("geteblk: size too big");

 loop:
 loop:

-       s = spl6();
-       for (dp = &bfreelist[BQUEUES-1]; dp > bfreelist; dp--)
-               if (dp->av_forw != dp)
-                       break;
-       if (dp == bfreelist) {          /* no free blocks */
-               dp->b_flags |= B_WANTED;
-               sleep((caddr_t)dp, PRIBIO+1);
-               goto loop;
-       }
-       splx(s);
-       bp = dp->av_forw;
-       notavail(bp);
-       if (bp->b_flags & B_DELWRI) {
-               bp->b_flags |= B_ASYNC;
-               bwrite(bp);
-               goto loop;
-       }
-#ifdef TRACE
-       trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
-#endif
-       bp->b_flags = B_BUSY|B_INVAL;
-       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 = getnewbuf();
+       bp->b_flags |= B_INVAL;
+       bfree(bp);
+       bremhash(bp);
+       flist = &bfreelist[BQ_AGE];
+       binshash(bp, flist);

        bp->b_dev = (dev_t)NODEV;
        bp->b_dev = (dev_t)NODEV;

-       bp->b_bcount = size;
-       return(bp);
+#ifdef SECSIZE
+       bp->b_blksize = DEV_BSIZE;
+#endif SECSIZE
+       bp->b_error = 0;
+       if (brealloc(bp, size) == 0)
+               goto loop;
+       return (bp);

 }
 
 /*
  * Allocate space associated with a buffer.
 }
 
 /*
  * Allocate space associated with a buffer.

+ * If can't get space, buffer is released

  */
 brealloc(bp, size)
        register struct buf *bp;
  */
 brealloc(bp, size)
        register struct buf *bp;


@@ -458,136 +432,139 @@ brealloc(bp, size)
        int s;
 
        /*
        int s;
 
        /*

-        * First need to make sure that all overlaping previous I/O
+        * First need to make sure that all overlapping previous I/O

         * is dispatched with.
         */
        if (size == bp->b_bcount)
         * is dispatched with.
         */
        if (size == bp->b_bcount)

-               return;
-       if (size < bp->b_bcount) {
-               bp->b_bcount = size;
-               return;
-       }
-       start = bp->b_blkno + (bp->b_bcount / DEV_BSIZE);
-       last = bp->b_blkno + (size / DEV_BSIZE) - 1;
-       if (bp->b_bcount == 0) {
-               start++;
-               if (start == last)
-                       goto allocit;
+               return (1);
+       if (size < bp->b_bcount) { 
+               if (bp->b_flags & B_DELWRI) {
+                       bwrite(bp);
+                       return (0);
+               }
+               if (bp->b_flags & B_LOCKED)
+                       panic("brealloc");
+               return (allocbuf(bp, size));

        }
        }

+       bp->b_flags &= ~B_DONE;
+       if (bp->b_dev == NODEV)
+               return (allocbuf(bp, size));
+
+       trace(TR_BREALLOC, pack(bp->b_dev, size), bp->b_blkno);
+       /*
+        * Search cache for any buffers that overlap the one that we
+        * are trying to allocate. Overlapping buffers must be marked
+        * invalid, after being written out if they are dirty. (indicated
+        * by B_DELWRI) A disk block must be mapped by at most one buffer
+        * at any point in time. Care must be taken to avoid deadlocking
+        * when two buffer are trying to get the same set of disk blocks.
+        */
+       start = bp->b_blkno;
+#ifdef SECSIZE
+       last = start + size/bp->b_blksize - 1;
+#else SECSIZE
+       last = start + btodb(size) - 1;
+#endif SECSIZE

        dp = BUFHASH(bp->b_dev, bp->b_blkno);
 loop:
        dp = BUFHASH(bp->b_dev, bp->b_blkno);
 loop:

-       (void) spl0();

        for (ep = dp->b_forw; ep != dp; ep = ep->b_forw) {
        for (ep = dp->b_forw; ep != dp; ep = ep->b_forw) {

-               if (ep->b_blkno < start || ep->b_blkno > last ||
-                   ep->b_dev != bp->b_dev || ep->b_flags&B_INVAL)
+               if (ep == bp || ep->b_dev != bp->b_dev || (ep->b_flags&B_INVAL))
+                       continue;
+               /* look for overlap */
+               if (ep->b_bcount == 0 || ep->b_blkno > last ||
+#ifdef SECSIZE
+                   ep->b_blkno + ep->b_bcount/ep->b_blksize <= start)
+#else SECSIZE
+                   ep->b_blkno + btodb(ep->b_bcount) <= start)
+#endif SECSIZE

                        continue;
                        continue;

-               s = spl6();
+               s = splbio();

                if (ep->b_flags&B_BUSY) {
                        ep->b_flags |= B_WANTED;
                        sleep((caddr_t)ep, PRIBIO+1);
                        splx(s);
                        goto loop;
                }
                if (ep->b_flags&B_BUSY) {
                        ep->b_flags |= B_WANTED;
                        sleep((caddr_t)ep, PRIBIO+1);
                        splx(s);
                        goto loop;
                }

-               (void) spl0();
-               /*
-                * What we would really like to do is kill this
-                * I/O since it is now useless. We cannot do that
-                * so we force it to complete, so that it cannot
-                * over-write our useful data later.
-                */
+               splx(s);
+               notavail(ep);

                if (ep->b_flags & B_DELWRI) {
                if (ep->b_flags & B_DELWRI) {

-                       notavail(ep);
-                       ep->b_flags |= B_ASYNC;

                        bwrite(ep);
                        goto loop;
                }
                        bwrite(ep);
                        goto loop;
                }

+               ep->b_flags |= B_INVAL;
+               brelse(ep);

        }
        }

-allocit:
-       /*
-        * Here the buffer is already available, so all we
-        * need to do is set the size. Someday a better memory
-        * management scheme will be implemented.
-        */
-       bp->b_bcount = size;
+       return (allocbuf(bp, size));

 }
 
 /*
 }
 
 /*

- * Release space associated with a buffer.
+ * Find a buffer which is available for use.
+ * Select something from a free list.
+ * Preference is to AGE list, then LRU list.

  */
  */

-bfree(bp)
-       struct buf *bp;
+struct buf *
+getnewbuf()

 {
 {

-       /*
-        * Here the buffer does not change, so all we
-        * need to do is set the size. Someday a better memory
-        * management scheme will be implemented.
-        */
-       bp->b_bcount = 0;
+       register struct buf *bp, *dp;
+       int s;
+
+loop:
+       s = splbio();
+       for (dp = &bfreelist[BQ_AGE]; dp > bfreelist; dp--)
+               if (dp->av_forw != dp)
+                       break;
+       if (dp == bfreelist) {          /* no free blocks */
+               dp->b_flags |= B_WANTED;
+               sleep((caddr_t)dp, PRIBIO+1);
+               splx(s);
+               goto loop;
+       }
+       splx(s);
+       bp = dp->av_forw;
+       notavail(bp);
+       if (bp->b_flags & B_DELWRI) {
+               bp->b_flags |= B_ASYNC;
+               bwrite(bp);
+               goto loop;
+       }
+       trace(TR_BRELSE, pack(bp->b_dev, bp->b_bufsize), bp->b_blkno);
+       bp->b_flags = B_BUSY;
+       return (bp);

 }
 
 /*
  * Wait for I/O completion on the buffer; return errors
  * to the user.
  */
 }
 
 /*
  * Wait for I/O completion on the buffer; return errors
  * to the user.
  */

-iowait(bp)
+biowait(bp)

        register struct buf *bp;
 {
        int s;
 
        register struct buf *bp;
 {
        int s;
 

-       s = spl6();
+       s = splbio();

        while ((bp->b_flags&B_DONE)==0)
                sleep((caddr_t)bp, PRIBIO);
        splx(s);
        while ((bp->b_flags&B_DONE)==0)
                sleep((caddr_t)bp, PRIBIO);
        splx(s);

-       geterror(bp);
+       if (u.u_error == 0)                     /* XXX */
+               u.u_error = geterror(bp);

 }
 
 }
 

-#ifdef UNFAST

 /*
 /*

- * Unlink a buffer from the available list and mark it busy.
- * (internal interface)
+ * Mark I/O complete on a buffer.
+ * If someone should be called, e.g. the pageout
+ * daemon, do so.  Otherwise, wake up anyone
+ * waiting for it.

  */
  */

-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;
+biodone(bp)
+       register struct buf *bp;

 {
 {

-       register int s;

 
        if (bp->b_flags & B_DONE)
 
        if (bp->b_flags & B_DONE)

-               panic("dup iodone");
+               panic("dup biodone");

        bp->b_flags |= B_DONE;
        bp->b_flags |= B_DONE;

-       if (bp->b_flags & B_DIRTY) {
-               if (bp->b_flags & B_ERROR)
-                       panic("IO err in push");
-               s = spl6();
-               bp->av_forw = bclnlist;
-               bp->b_bcount = swsize[bp - swbuf];
-               bp->b_pfcent = swpf[bp - swbuf];
-               cnt.v_pgout++;
-               cnt.v_pgpgout += bp->b_bcount / NBPG;
-               bclnlist = bp;
-               if (bswlist.b_flags & B_WANTED)
-                       wakeup((caddr_t)&proc[2]);
-               splx(s);
+       if (bp->b_flags & B_CALL) {
+               bp->b_flags &= ~B_CALL;
+               (*bp->b_iodone)(bp);

                return;
        }
        if (bp->b_flags&B_ASYNC)
                return;
        }
        if (bp->b_flags&B_ASYNC)


@@ -599,44 +576,88 @@ register struct buf *bp;
 }
 
 /*
 }
 
 /*

- * Zero the core associated with a buffer.
+ * Insure that no part of a specified block is in an incore buffer.
+#ifdef SECSIZE
+ * "size" is given in device blocks (the units of b_blkno).
+#endif SECSIZE
+#ifdef SECSIZE
+ * "size" is given in device blocks (the units of b_blkno).
+#endif SECSIZE

  */
  */

-clrbuf(bp)
-       struct buf *bp;
+blkflush(dev, blkno, size)
+       dev_t dev;
+       daddr_t blkno;
+#ifdef SECSIZE
+       int size;
+#else SECSIZE
+       long size;
+#endif SECSIZE

 {
 {

-       register int *p;
-       register int c;
-
-       p = bp->b_un.b_words;
-       c = bp->b_bcount/sizeof(int);
-       do
-               *p++ = 0;
-       while (--c);
-       bp->b_resid = 0;
+       register struct buf *ep;
+       struct buf *dp;
+       daddr_t start, last;
+       int s;
+
+       start = blkno;
+#ifdef SECSIZE
+       last = start + size - 1;
+#else SECSIZE
+       last = start + btodb(size) - 1;
+#endif SECSIZE
+       dp = BUFHASH(dev, blkno);
+loop:
+       for (ep = dp->b_forw; ep != dp; ep = ep->b_forw) {
+               if (ep->b_dev != dev || (ep->b_flags&B_INVAL))
+                       continue;
+               /* look for overlap */
+               if (ep->b_bcount == 0 || ep->b_blkno > last ||
+#ifdef SECSIZE
+                   ep->b_blkno + ep->b_bcount / ep->b_blksize <= start)
+#else SECSIZE
+                   ep->b_blkno + btodb(ep->b_bcount) <= start)
+#endif SECSIZE
+                       continue;
+               s = splbio();
+               if (ep->b_flags&B_BUSY) {
+                       ep->b_flags |= B_WANTED;
+                       sleep((caddr_t)ep, PRIBIO+1);
+                       splx(s);
+                       goto loop;
+               }
+               if (ep->b_flags & B_DELWRI) {
+                       splx(s);
+                       notavail(ep);
+                       bwrite(ep);
+                       goto loop;
+               }
+               splx(s);
+       }

 }
 
 /*
 }
 
 /*

- * make sure all write-behind blocks
+ * Make sure all write-behind blocks

  * on dev (or NODEV for all)
  * are flushed out.
  * (from umount and update)
  * on dev (or NODEV for all)
  * are flushed out.
  * (from umount and update)

- * (and temporarily pagein)

  */
 bflush(dev)
  */
 bflush(dev)

-dev_t dev;
+       dev_t dev;

 {
        register struct buf *bp;
        register struct buf *flist;
        int s;
 
 loop:
 {
        register struct buf *bp;
        register struct buf *flist;
        int s;
 
 loop:

-       s = spl6();
-       for (flist = bfreelist; flist < &bfreelist[BQUEUES]; flist++)
+       s = splbio();
+       for (flist = bfreelist; flist < &bfreelist[BQ_EMPTY]; flist++)

        for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
        for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {

-               if (bp->b_flags&B_DELWRI && (dev == NODEV||dev==bp->b_dev)) {
+               if ((bp->b_flags & B_DELWRI) == 0)
+                       continue;
+               if (dev == NODEV || dev == bp->b_dev) {

                        bp->b_flags |= B_ASYNC;
                        notavail(bp);
                        bwrite(bp);
                        bp->b_flags |= B_ASYNC;
                        notavail(bp);
                        bwrite(bp);

+                       splx(s);

                        goto loop;
                }
        }
                        goto loop;
                }
        }


@@ -645,17 +666,17 @@ loop:
 
 /*
  * Pick up the device's error number and pass it to the user;
 
 /*
  * Pick up the device's error number and pass it to the user;

- * if there is an error but the number is 0 set a generalized
- * code.  Actually the latter is always true because devices
- * don't yet return specific errors.
+ * if there is an error but the number is 0 set a generalized code.

  */
 geterror(bp)
  */
 geterror(bp)

-register struct buf *bp;
+       register struct buf *bp;

 {
 {

+       int error = 0;

 
        if (bp->b_flags&B_ERROR)
 
        if (bp->b_flags&B_ERROR)

-               if ((u.u_error = bp->b_error)==0)
-                       u.u_error = EIO;
+               if ((error = bp->b_error)==0)
+                       return (EIO);
+       return (error);

 }
 
 /*
 }
 
 /*


@@ -670,7 +691,7 @@ register struct buf *bp;
  * correctness.                                                ... kre
  */
 binval(dev)
  * correctness.                                                ... kre
  */
 binval(dev)

-dev_t dev;
+       dev_t dev;

 {
        register struct buf *bp;
        register struct bufhd *hp;
 {
        register struct buf *bp;
        register struct bufhd *hp;