sanity checks in getblk() and geteblk()

[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 02c6db1..76a6772 100644 (file)
--- a/usr/src/sys/kern/vfs_cluster.c
+++ b/usr/src/sys/kern/vfs_cluster.c
@@ -1,16 +1,23 @@
-/*     vfs_cluster.c   4.33    82/06/07        */
-
-#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"
+/*
+ * Copyright (c) 1982 Regents of the University of California.
+ * All rights reserved.  The Berkeley software License Agreement
+ * specifies the terms and conditions for redistribution.
+ *
+ *     @(#)vfs_cluster.c       6.8 (Berkeley) %G%
+ */
+
+#include "../machine/pte.h"
+
+#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.
 
 /*
  * Read in (if necessary) the block and return a buffer pointer.


@@ -23,15 +30,19 @@ bread(dev, blkno, size)
 {
        register struct buf *bp;
 
 {
        register struct buf *bp;
 

+       if (size == 0)
+               panic("bread: size 0");

        bp = getblk(dev, blkno, size);
        if (bp->b_flags&B_DONE) {
        bp = getblk(dev, blkno, size);
        if (bp->b_flags&B_DONE) {

-               trace(TR_BREADHIT, dev, blkno);
+               trace(TR_BREADHIT, pack(dev, size), blkno);

                return(bp);
        }
        bp->b_flags |= B_READ;
                return(bp);
        }
        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);

-       trace(TR_BREADMISS, dev, blkno);
-       u.u_vm.vm_inblk++;              /* pay for read */
+       trace(TR_BREADMISS, pack(dev, size), blkno);
+       u.u_ru.ru_inblock++;            /* pay for read */

        biowait(bp);
        return(bp);
 }
        biowait(bp);
        return(bp);
 }


@@ -41,10 +52,10 @@ 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, size, rablkno, rasize)
+breada(dev, blkno, size, rablkno, rabsize)

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

-       daddr_t rablkno; int rasize;
+       daddr_t rablkno; int rabsize;

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


@@ -58,11 +69,13 @@ breada(dev, blkno, size, rablkno, rasize)
                bp = getblk(dev, blkno, size);
                if ((bp->b_flags&B_DONE) == 0) {
                        bp->b_flags |= B_READ;
                bp = getblk(dev, blkno, size);
                if ((bp->b_flags&B_DONE) == 0) {
                        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);

-                       trace(TR_BREADMISS, dev, blkno);
-                       u.u_vm.vm_inblk++;              /* pay for read */
+                       trace(TR_BREADMISS, pack(dev, size), blkno);
+                       u.u_ru.ru_inblock++;            /* pay for read */

                } else
                } else

-                       trace(TR_BREADHIT, dev, blkno);
+                       trace(TR_BREADHIT, pack(dev, size), blkno);

        }
 
        /*
        }
 
        /*


@@ -70,15 +83,17 @@ breada(dev, blkno, size, rablkno, rasize)
         * on it also (as above).
         */
        if (rablkno && !incore(dev, rablkno)) {
         * on it also (as above).
         */
        if (rablkno && !incore(dev, rablkno)) {

-               rabp = getblk(dev, rablkno, rasize);
+               rabp = getblk(dev, rablkno, rabsize);

                if (rabp->b_flags & B_DONE) {
                        brelse(rabp);
                if (rabp->b_flags & B_DONE) {
                        brelse(rabp);

-                       trace(TR_BREADHITRA, dev, blkno);
+                       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);

-                       trace(TR_BREADMISSRA, dev, rablock);
-                       u.u_vm.vm_inblk++;              /* pay in advance */
+                       trace(TR_BREADMISSRA, pack(dev, rabsize), rablock);
+                       u.u_ru.ru_inblock++;            /* pay in advance */

                }
        }
 
                }
        }
 


@@ -103,26 +118,24 @@ bwrite(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);
+       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 */
-       trace(TR_BWRITE, bp->b_dev, bp->b_blkno);
+               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);
 
        /*
         * 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.
        (*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.

-        * Otherwise, the i/o must be finished and we check for
-        * an error.

         */
        if ((flag&B_ASYNC) == 0) {
                biowait(bp);
                brelse(bp);
        } else if (flag & B_DELWRI)
                bp->b_flags |= B_AGE;
         */
        if ((flag&B_ASYNC) == 0) {
                biowait(bp);
                brelse(bp);
        } else if (flag & B_DELWRI)
                bp->b_flags |= B_AGE;

-       else
-               geterror(bp);

 }
 
 /*
 }
 
 /*


@@ -139,7 +152,7 @@ bdwrite(bp)
        register int flags;
 
        if ((bp->b_flags&B_DELWRI) == 0)
        register int flags;
 
        if ((bp->b_flags&B_DELWRI) == 0)

-               u.u_vm.vm_oublk++;              /* noone paid yet */
+               u.u_ru.ru_oublock++;            /* noone paid yet */

        flags = bdevsw[major(bp->b_dev)].d_flags;
        if(flags & B_TAPE)
                bawrite(bp);
        flags = bdevsw[major(bp->b_dev)].d_flags;
        if(flags & B_TAPE)
                bawrite(bp);


@@ -169,6 +182,7 @@ brelse(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 someone's waiting for the buffer, or
         * is waiting for a buffer wake 'em up.


@@ -189,9 +203,13 @@ brelse(bp)
         * Stick the buffer back on a free list.
         */
        s = spl6();
         * Stick the buffer back on a free list.
         */
        s = spl6();

-       if (bp->b_flags & (B_ERROR|B_INVAL)) {
+       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 = &bfreelist[BQ_AGE];

                binsheadfree(bp, flist);
        } else {
                if (bp->b_flags & B_LOCKED)
                binsheadfree(bp, flist);
        } else {
                if (bp->b_flags & B_LOCKED)


@@ -252,11 +270,21 @@ getblk(dev, blkno, size)
        daddr_t blkno;
        int size;
 {
        daddr_t blkno;
        int size;
 {

-       register struct buf *bp, *dp, *ep;
+       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
        /*
         * Search the cache for the block.  If we hit, but
         * the buffer is in use for i/o, then we wait until


@@ -277,42 +305,22 @@ loop:
                }
                splx(s);
                notavail(bp);
                }
                splx(s);
                notavail(bp);

-               brealloc(bp, size);
+               if (bp->b_bcount != size && brealloc(bp, size) == 0)
+                       goto loop;

                bp->b_flags |= B_CACHE;
                return(bp);
        }
        if (major(dev) >= nblkdev)
                panic("blkdev");
                bp->b_flags |= B_CACHE;
                return(bp);
        }
        if (major(dev) >= nblkdev)
                panic("blkdev");

-       /*
-        * Not found in the cache, select something from
-        * a free list.  Preference is to LRU list, then AGE list.
-        */
-       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;
-       }
-       trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
-       bp->b_flags = B_BUSY;
+       bp = getnewbuf();

        bfree(bp);
        bremhash(bp);
        binshash(bp, dp);
        bp->b_dev = dev;
        bp->b_blkno = blkno;
        bfree(bp);
        bremhash(bp);
        binshash(bp, dp);
        bp->b_dev = dev;
        bp->b_blkno = blkno;

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

        return(bp);
 }
 
        return(bp);
 }
 


@@ -324,39 +332,27 @@ 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;
-       }
-       trace(TR_BRELSE, bp->b_dev, bp->b_blkno);
-       bp->b_flags = B_BUSY|B_INVAL;
+       bp = getnewbuf();
+       bp->b_flags |= B_INVAL;

        bfree(bp);
        bremhash(bp);
        bfree(bp);
        bremhash(bp);

-       binshash(bp, dp);
+       flist = &bfreelist[BQ_AGE];
+       binshash(bp, flist);

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

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

        return(bp);
 }
 
 /*
  * Allocate space associated with a buffer.
        return(bp);
 }
 
 /*
  * 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;


@@ -372,65 +368,92 @@ brealloc(bp, size)
         * is dispatched with.
         */
        if (size == bp->b_bcount)
         * is dispatched with.
         */
        if (size == bp->b_bcount)

-               return;
-       if (size < bp->b_bcount || bp->b_dev == NODEV)
-               goto allocit;
-
-       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;
+       last = start + btodb(size) - 1;

        dp = BUFHASH(bp->b_dev, bp->b_blkno);
 loop:
        for (ep = dp->b_forw; ep != dp; ep = ep->b_forw) {
        dp = BUFHASH(bp->b_dev, bp->b_blkno);
 loop:
        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 ||
+                   ep->b_blkno + btodb(ep->b_bcount) <= start)

                        continue;
                s = spl6();
                if (ep->b_flags&B_BUSY) {
                        ep->b_flags |= B_WANTED;
                        sleep((caddr_t)ep, PRIBIO+1);
                        continue;
                s = spl6();
                if (ep->b_flags&B_BUSY) {
                        ep->b_flags |= B_WANTED;
                        sleep((caddr_t)ep, PRIBIO+1);

-                       (void) splx(s);
+                       splx(s);

                        goto loop;
                }
                        goto loop;
                }

-               (void) splx(s);
-               /*
-                * 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 = spl6();
+       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);

 }
 
 /*
 }
 
 /*


@@ -446,38 +469,26 @@ biowait(bp)
        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);

 }
 
 /*
 }
 
 /*

- * 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.
+ * 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.

  */
 biodone(bp)
        register struct buf *bp;
 {
  */
 biodone(bp)
        register struct buf *bp;
 {

-       register int s;

 
        if (bp->b_flags & B_DONE)
                panic("dup biodone");
        bp->b_flags |= B_DONE;
 
        if (bp->b_flags & B_DONE)
                panic("dup biodone");
        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)


@@ -489,11 +500,51 @@ biodone(bp)
 }
 
 /*
 }
 
 /*

- * make sure all write-behind blocks
+ * Insure that no part of a specified block is in an incore buffer.
+ */
+blkflush(dev, blkno, size)
+       dev_t dev;
+       daddr_t blkno;
+       long size;
+{
+       register struct buf *ep;
+       struct buf *dp;
+       daddr_t start, last;
+       int s;
+
+       start = blkno;
+       last = start + btodb(size) - 1;
+       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 ||
+                   ep->b_blkno + btodb(ep->b_bcount) <= start)
+                       continue;
+               s = spl6();
+               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

  * 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)
        dev_t dev;
  */
 bflush(dev)
        dev_t dev;


@@ -504,7 +555,7 @@ bflush(dev)
 
 loop:
        s = spl6();
 
 loop:
        s = spl6();

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

        for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
                if ((bp->b_flags & B_DELWRI) == 0)
                        continue;
        for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
                if ((bp->b_flags & B_DELWRI) == 0)
                        continue;


@@ -512,6 +563,7 @@ loop:
                        bp->b_flags |= B_ASYNC;
                        notavail(bp);
                        bwrite(bp);
                        bp->b_flags |= B_ASYNC;
                        notavail(bp);
                        bwrite(bp);

+                       splx(s);

                        goto loop;
                }
        }
                        goto loop;
                }
        }


@@ -520,17 +572,17 @@ 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)
        register struct buf *bp;
 {
  */
 geterror(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);

 }
 
 /*
 }
 
 /*