major overhaul to generalize for a logical buffer pool

SCCS-vsn: sys/kern/vfs_bio.c 7.15
SCCS-vsn: sys/kern/vfs_cluster.c 7.15

diff --git a/usr/src/sys/kern/vfs_bio.c b/usr/src/sys/kern/vfs_bio.c
index 4b5eaad..7d1af52 100644 (file)
--- a/usr/src/sys/kern/vfs_bio.c
+++ b/usr/src/sys/kern/vfs_bio.c
@@ -14,13 +14,14 @@
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *

- *     @(#)vfs_bio.c   7.14 (Berkeley) %G%
+ *     @(#)vfs_bio.c   7.15 (Berkeley) %G%

  */
 
 #include "param.h"
 #include "user.h"
 #include "buf.h"
 #include "vnode.h"
  */
 
 #include "param.h"
 #include "user.h"
 #include "buf.h"
 #include "vnode.h"

+#include "mount.h"

 #include "trace.h"
 #include "ucred.h"
 
 #include "trace.h"
 #include "ucred.h"
 


@@ -159,7 +160,7 @@ bwrite(bp)
        if ((flag&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */
        trace(TR_BWRITE,
        if ((flag&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */
        trace(TR_BWRITE,

-           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bcount), bp->b_blkno);
+           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bcount), bp->b_lblkno);

        if (bp->b_bcount > bp->b_bufsize)
                panic("bwrite");
        VOP_STRATEGY(bp);
        if (bp->b_bcount > bp->b_bufsize)
                panic("bwrite");
        VOP_STRATEGY(bp);


@@ -193,22 +194,15 @@ bdwrite(bp)
 
        if ((bp->b_flags&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */
 
        if ((bp->b_flags&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */

-#ifdef notdef

        /*
        /*

-        * This does not work for buffers associated with
-        * vnodes that are remote - they have no dev.
-        * Besides, we don't use bio with tapes, so rather
-        * than develop a fix, we just ifdef this out for now.
+        * If this is a tape drive, the write must be initiated.

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

-       else {
+       } else {

                bp->b_flags |= B_DELWRI | B_DONE;
                brelse(bp);
        }
                bp->b_flags |= B_DELWRI | B_DONE;
                brelse(bp);
        }

-#endif
-       bp->b_flags |= B_DELWRI | B_DONE;
-       brelse(bp);

 }
 
 /*
 }
 
 /*


@@ -232,10 +226,10 @@ brelse(bp)
        register s;
 
        trace(TR_BRELSE,
        register s;
 
        trace(TR_BRELSE,

-           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_blkno);
+           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_lblkno);

        /*
        /*

-        * If someone's waiting for the buffer, or
-        * is waiting for a buffer wake 'em up.
+        * If a process is waiting for the buffer, or
+        * is waiting for a free buffer, awaken it.

         */
        if (bp->b_flags&B_WANTED)
                wakeup((caddr_t)bp);
         */
        if (bp->b_flags&B_WANTED)
                wakeup((caddr_t)bp);


@@ -243,15 +237,22 @@ brelse(bp)
                bfreelist[0].b_flags &= ~B_WANTED;
                wakeup((caddr_t)bfreelist);
        }
                bfreelist[0].b_flags &= ~B_WANTED;
                wakeup((caddr_t)bfreelist);
        }

-       if (bp->b_flags & B_NOCACHE) {
+       /*
+        * Retry I/O for locked buffers rather than invalidating them.
+        */
+       if ((bp->b_flags & B_ERROR) && (bp->b_flags & B_LOCKED))
+               bp->b_flags &= ~B_ERROR;
+
+       /*
+        * Disassociate buffers that are no longer valid.
+        */
+       if (bp->b_flags & (B_NOCACHE|B_ERROR))

                bp->b_flags |= B_INVAL;
                bp->b_flags |= B_INVAL;

+       if ((bp->b_bufsize <= 0) || (bp->b_flags & (B_ERROR|B_INVAL))) {
+               if (bp->b_vp)
+                       brelvp(bp);
+               bp->b_flags &= ~B_DELWRI;

        }
        }

-       if (bp->b_flags&B_ERROR)
-               if (bp->b_flags & B_LOCKED)
-                       bp->b_flags &= ~B_ERROR;        /* try again later */
-               else
-                       brelvp(bp);                     /* no assoc */
-

        /*
         * Stick the buffer back on a free list.
         */
        /*
         * Stick the buffer back on a free list.
         */


@@ -290,12 +291,15 @@ incore(vp, blkno)
 
        dp = BUFHASH(vp, blkno);
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
 
        dp = BUFHASH(vp, blkno);
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)

-               if (bp->b_blkno == blkno && bp->b_vp == vp &&
+               if (bp->b_lblkno == blkno && bp->b_vp == vp &&

                    (bp->b_flags & B_INVAL) == 0)
                        return (1);
        return (0);
 }
 
                    (bp->b_flags & B_INVAL) == 0)
                        return (1);
        return (0);
 }
 

+/*
+ * Return a block if it is in memory.
+ */

 baddr(vp, blkno, size, cred, bpp)
        struct vnode *vp;
        daddr_t blkno;
 baddr(vp, blkno, size, cred, bpp)
        struct vnode *vp;
        daddr_t blkno;


@@ -319,13 +323,6 @@ baddr(vp, blkno, size, cred, bpp)
  * 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.
  * 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.


@@ -354,9 +351,13 @@ getblk(vp, blkno, size)
         * 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
         * 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

+        *
+        * Make it a panic to see if it ever really happens. mkm 11/89

         */
         */

-       if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-DEV_BSHIFT))
+       if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-DEV_BSHIFT)) {
+               panic("getblk: blkno too big");

                blkno = 1 << ((sizeof(int)*NBBY-DEV_BSHIFT) + 1);
                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


@@ -365,7 +366,7 @@ getblk(vp, blkno, size)
        dp = BUFHASH(vp, blkno);
 loop:
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
        dp = BUFHASH(vp, blkno);
 loop:
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {

-               if (bp->b_blkno != blkno || bp->b_vp != vp ||
+               if (bp->b_lblkno != blkno || bp->b_vp != vp ||

                    bp->b_flags&B_INVAL)
                        continue;
                s = splbio();
                    bp->b_flags&B_INVAL)
                        continue;
                s = splbio();


@@ -378,27 +379,19 @@ loop:
                splx(s);
                notavail(bp);
                if (bp->b_bcount != size) {
                splx(s);
                notavail(bp);
                if (bp->b_bcount != size) {

-                       if (bp->b_bcount < size && (bp->b_flags&B_DELWRI)) {
-                               bp->b_flags &= ~B_ASYNC;
-                               (void) bwrite(bp);
-                               goto loop;
-                       }
-                       if (brealloc(bp, size) == 0)
-                               goto loop;
-               }
-               if (bp->b_bcount != size && brealloc(bp, size) == 0)
+                       printf("getblk: stray size");
+                       bp->b_flags |= B_INVAL;
+                       bwrite(bp);

                        goto loop;
                        goto loop;

+               }

                bp->b_flags |= B_CACHE;
                return (bp);
        }
        bp = getnewbuf();
        bfree(bp);
        bremhash(bp);
                bp->b_flags |= B_CACHE;
                return (bp);
        }
        bp = getnewbuf();
        bfree(bp);
        bremhash(bp);

-       if (bp->b_vp)
-               brelvp(bp);
-       VREF(vp);
-       bp->b_vp = vp;
-       bp->b_dev = vp->v_rdev;
+       bgetvp(vp, bp);
+       bp->b_lblkno = blkno;

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


@@ -406,8 +399,7 @@ loop:
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, dp);
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, dp);

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

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


@@ -423,27 +415,23 @@ geteblk(size)
 
        if (size > MAXBSIZE)
                panic("geteblk: size too big");
 
        if (size > MAXBSIZE)
                panic("geteblk: size too big");

-loop:

        bp = getnewbuf();
        bp->b_flags |= B_INVAL;
        bfree(bp);
        bremhash(bp);
        flist = &bfreelist[BQ_AGE];
        bp = getnewbuf();
        bp->b_flags |= B_INVAL;
        bfree(bp);
        bremhash(bp);
        flist = &bfreelist[BQ_AGE];

-       brelvp(bp);

 #ifdef SECSIZE
        bp->b_blksize = DEV_BSIZE;
 #endif SECSIZE
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, flist);
 #ifdef SECSIZE
        bp->b_blksize = DEV_BSIZE;
 #endif SECSIZE
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, flist);

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

        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;


@@ -454,72 +442,9 @@ brealloc(bp, size)
        struct buf *dp;
        int s;
 
        struct buf *dp;
        int s;
 

-       /*
-        * First need to make sure that all overlapping previous I/O
-        * is dispatched with.
-        */

        if (size == bp->b_bcount)
        if (size == bp->b_bcount)

-               return (1);
-       if (size < bp->b_bcount) { 
-               if (bp->b_flags & B_DELWRI) {
-                       (void) bwrite(bp);
-                       return (0);
-               }
-               if (bp->b_flags & B_LOCKED)
-                       panic("brealloc");
-               return (allocbuf(bp, size));
-       }
-       bp->b_flags &= ~B_DONE;
-       if (bp->b_vp == (struct vnode *)0)
-               return (allocbuf(bp, size));
-
-       trace(TR_BREALLOC,
-           pack(bp->b_vp->v_mount->m_fsid[0], 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_vp, bp->b_blkno);
-loop:
-       for (ep = dp->b_forw; ep != dp; ep = ep->b_forw) {
-               if (ep == bp || ep->b_vp != bp->b_vp ||
-                   (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;
-               }
-               splx(s);
-               notavail(ep);
-               if (ep->b_flags & B_DELWRI) {
-                       (void) bwrite(ep);
-                       goto loop;
-               }
-               ep->b_flags |= B_INVAL;
-               brelse(ep);
-       }
-       return (allocbuf(bp, size));
+               return;
+       allocbuf(bp, size);

 }
 
 /*
 }
 
 /*


@@ -553,8 +478,9 @@ loop:
                goto loop;
        }
        trace(TR_BRELSE,
                goto loop;
        }
        trace(TR_BRELSE,

-           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_blkno);
-       brelvp(bp);
+           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_lblkno);
+       if (bp->b_vp)
+               brelvp(bp);

        if (bp->b_rcred != NOCRED) {
                cred = bp->b_rcred;
                bp->b_rcred = NOCRED;
        if (bp->b_rcred != NOCRED) {
                cred = bp->b_rcred;
                bp->b_rcred = NOCRED;


@@ -624,7 +550,7 @@ biodone(bp)
 /*
  * Ensure that no part of a specified block is in an incore buffer.
 #ifdef SECSIZE
 /*
  * Ensure 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).
+ * "size" is given in device blocks (the units of b_lblkno).

 #endif SECSIZE
 #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).


@@ -661,8 +587,8 @@ loop:
                        if (ep->b_vp != vp || (ep->b_flags & B_INVAL))
                                continue;
                        /* look for overlap */
                        if (ep->b_vp != vp || (ep->b_flags & B_INVAL))
                                continue;
                        /* look for overlap */

-                       if (ep->b_bcount == 0 || ep->b_blkno > ecurblk ||
-                           ep->b_blkno + btodb(ep->b_bcount) <= curblk)
+                       if (ep->b_bcount == 0 || ep->b_lblkno > ecurblk ||
+                           ep->b_lblkno + btodb(ep->b_bcount) <= curblk)

                                continue;
                        s = splbio();
                        if (ep->b_flags&B_BUSY) {
                                continue;
                        s = splbio();
                        if (ep->b_flags&B_BUSY) {


@@ -688,92 +614,213 @@ loop:
  * Make sure all write-behind blocks associated
  * with mount point are flushed out (from sync).
  */
  * Make sure all write-behind blocks associated
  * with mount point are flushed out (from sync).
  */

-bflush(mountp)
+mntflushbuf(mountp, flags)

        struct mount *mountp;
        struct mount *mountp;

+       int flags;

 {
 {

-       register struct buf *bp;

        register struct vnode *vp;
        register struct vnode *vp;

-       register struct buf *flist;
+
+loop:
+       for (vp = mountp->m_mounth; vp; vp = vp->v_mountf) {
+               if (vget(vp))
+                       goto loop;
+               vflushbuf(vp, flags);
+               vput(vp);
+       }
+}
+
+/*
+ * Flush all dirty buffers associated with a vnode.
+ */
+vflushbuf(vp, flags)
+       register struct vnode *vp;
+       int flags;
+{
+       register struct buf *bp;
+       struct buf *nbp;

        int s;
 
 loop:
        s = splbio();
        int s;
 
 loop:
        s = splbio();

-       for (flist = bfreelist; flist < &bfreelist[BQ_EMPTY]; flist++) {
-               for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
-                       if ((bp->b_flags & B_BUSY))
-                               continue;
-                       if ((bp->b_flags & B_DELWRI) == 0)
-                               continue;
-                       if ((vp = bp->b_vp) == NULL)
-                               continue;
-                       if (vp->v_mount == mountp ||
-                           (vp->v_type == VBLK && vp->v_mounton == mountp)) {
-                               splx(s);
-                               notavail(bp);
-                               (void) bawrite(bp);
-                               goto loop;
-                       }
+       for (bp = vp->v_blockh; bp; bp = nbp) {
+               nbp = bp->b_blockf;
+               if ((bp->b_flags & B_BUSY))
+                       continue;
+               if ((bp->b_flags & B_DELWRI) == 0)
+                       continue;
+               splx(s);
+               notavail(bp);
+               (void) bawrite(bp);
+               goto loop;
+       }
+       if ((flags & B_SYNC) == 0)
+               return;
+wloop:
+       s = splbio();
+       for (bp = vp->v_blockh; bp; bp = nbp) {
+               nbp = bp->b_blockf;
+               if (bp->b_flags & B_BUSY) {
+                       bp->b_flags |= B_WANTED;
+                       sleep((caddr_t)bp, PRIBIO+1);
+                       splx(s);
+                       goto wloop;

                }
                }

+               if ((bp->b_flags & B_DELWRI))
+                       goto loop;

        }
        }

-       splx(s);

 }
 
 /*
  * Invalidate in core blocks belonging to closed or umounted filesystem
  *
 }
 
 /*
  * Invalidate in core blocks belonging to closed or umounted filesystem
  *

- * We walk through the buffer pool and invalidate any buffers for the
- * indicated mount point. Normally this routine is preceeded by a bflush
- * call, so that on a quiescent filesystem there will be no dirty
- * buffers when we are done. We return the count of dirty buffers when
- * we are finished.
+ * Go through the list of vnodes associated with the file system;
+ * for each vnode invalidate any buffers that it holds. Normally
+ * this routine is preceeded by a bflush call, so that on a quiescent
+ * filesystem there will be no dirty buffers when we are done. Binval
+ * returns the count of dirty buffers when it is finished.

  */
  */

-binval(mountp)
+mntinvalbuf(mountp)

        struct mount *mountp;
 {
        struct mount *mountp;
 {

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

        register struct vnode *vp;
        register struct vnode *vp;

+       int dirty = 0;
+
+loop:
+       for (vp = mountp->m_mounth; vp; vp = vp->v_mountf) {
+               if (vget(vp))
+                       goto loop;
+               dirty += vinvalbuf(vp, 1);
+               vput(vp);
+       }
+       return (dirty);
+}
+
+/*
+ * Flush out and invalidate all buffers associated with a vnode.
+ * Called with the underlying object locked.
+ */
+vinvalbuf(vp, save)
+       register struct vnode *vp;
+       int save;
+{
+       register struct buf *bp;
+       struct buf *nbp;

        int s, dirty = 0;
        int s, dirty = 0;

-#define dp ((struct buf *)hp)

 
 loop:
 
 loop:

-       for (hp = bufhash; hp < &bufhash[BUFHSZ]; hp++) {
-               for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
-                       if ((vp = bp->b_vp) == NULL)
-                               continue;
-                       if (vp->v_mount != mountp &&
-                           (vp->v_type != VBLK || vp->v_mounton != mountp))
-                               continue;
-                       s = splbio();
-                       if (bp->b_flags & B_BUSY) {
-                               bp->b_flags |= B_WANTED;
-                               sleep((caddr_t)bp, PRIBIO+1);
-                               splx(s);
-                               goto loop;
-                       }
+       for (bp = vp->v_blockh; bp; bp = nbp) {
+               nbp = bp->b_blockf;
+               s = splbio();
+               if (bp->b_flags & B_BUSY) {
+                       bp->b_flags |= B_WANTED;
+                       sleep((caddr_t)bp, PRIBIO+1);

                        splx(s);
                        splx(s);

-                       notavail(bp);
+                       goto loop;
+               }
+               splx(s);
+               notavail(bp);
+               if (save) {

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

-                               (void) bawrite(bp);

                                dirty++;
                                dirty++;

-                               continue;
+                               (void) bwrite(bp);
+                               goto loop;

                        }
                        }

-                       bp->b_flags |= B_INVAL;
-                       brelvp(bp);
-                       brelse(bp);

                }
                }

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

        }
        }

+       if (vp->v_blockh != 0)
+               panic("vinvalbuf: flush failed");

        return (dirty);
 }
 
        return (dirty);
 }
 

+/*
+ * Associate a buffer with a vnode.
+ */
+bgetvp(vp, bp)
+       register struct vnode *vp;
+       register struct buf *bp;
+{
+
+       if (bp->b_vp)
+               panic("bgetvp: not free");
+       VREF(vp);
+       bp->b_vp = vp;
+       if (vp->v_type == VBLK || vp->v_type == VCHR)
+               bp->b_dev = vp->v_rdev;
+       else
+               bp->b_dev = NODEV;
+       /*
+        * Insert onto list for new vnode.
+        */
+       if (vp->v_blockh) {
+               bp->b_blockf = vp->v_blockh;
+               bp->b_blockb = &vp->v_blockh;
+               vp->v_blockh->b_blockb = &bp->b_blockf;
+               vp->v_blockh = bp;
+       } else {
+               vp->v_blockh = bp;
+               bp->b_blockb = &vp->v_blockh;
+               bp->b_blockf = NULL;
+       }
+}
+
+/*
+ * Disassociate a buffer from a vnode.
+ */

 brelvp(bp)
 brelvp(bp)

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

 {
 {

+       struct buf *bq;

        struct vnode *vp;
 
        if (bp->b_vp == (struct vnode *) 0)
        struct vnode *vp;
 
        if (bp->b_vp == (struct vnode *) 0)

-               return;
+               panic("brelvp: NULL");
+       /*
+        * Delete from old vnode list, if on one.
+        */
+       if (bp->b_blockb) {
+               if (bq = bp->b_blockf)
+                       bq->b_blockb = bp->b_blockb;
+               *bp->b_blockb = bq;
+               bp->b_blockf = NULL;
+               bp->b_blockb = NULL;
+       }

        vp = bp->b_vp;
        bp->b_vp = (struct vnode *) 0;
        vrele(vp);
 }
        vp = bp->b_vp;
        bp->b_vp = (struct vnode *) 0;
        vrele(vp);
 }

+
+/*
+ * Reassign a buffer from one vnode to another.
+ * Used to assign file specific control information
+ * (indirect blocks) to the vnode to which they belong.
+ */
+reassignbuf(bp, newvp)
+       register struct buf *bp;
+       register struct vnode *newvp;
+{
+       register struct buf *bq;
+
+       /*
+        * Delete from old vnode list, if on one.
+        */
+       if (bp->b_blockb) {
+               if (bq = bp->b_blockf)
+                       bq->b_blockb = bp->b_blockb;
+               *bp->b_blockb = bq;
+       }
+       /*
+        * Insert onto list for new vnode.
+        */
+       if (newvp->v_blockh) {
+               bp->b_blockf = newvp->v_blockh;
+               bp->b_blockb = &newvp->v_blockh;
+               newvp->v_blockh->b_blockb = &bp->b_blockf;
+               newvp->v_blockh = bp;
+       } else {
+               newvp->v_blockh = bp;
+               bp->b_blockb = &newvp->v_blockh;
+               bp->b_blockf = NULL;
+       }
+}

diff --git a/usr/src/sys/kern/vfs_cluster.c b/usr/src/sys/kern/vfs_cluster.c
index 549960a..7138384 100644 (file)
--- a/usr/src/sys/kern/vfs_cluster.c
+++ b/usr/src/sys/kern/vfs_cluster.c
@@ -14,13 +14,14 @@
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *

- *     @(#)vfs_cluster.c       7.14 (Berkeley) %G%
+ *     @(#)vfs_cluster.c       7.15 (Berkeley) %G%

  */
 
 #include "param.h"
 #include "user.h"
 #include "buf.h"
 #include "vnode.h"
  */
 
 #include "param.h"
 #include "user.h"
 #include "buf.h"
 #include "vnode.h"

+#include "mount.h"

 #include "trace.h"
 #include "ucred.h"
 
 #include "trace.h"
 #include "ucred.h"
 


@@ -159,7 +160,7 @@ bwrite(bp)
        if ((flag&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */
        trace(TR_BWRITE,
        if ((flag&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */
        trace(TR_BWRITE,

-           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bcount), bp->b_blkno);
+           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bcount), bp->b_lblkno);

        if (bp->b_bcount > bp->b_bufsize)
                panic("bwrite");
        VOP_STRATEGY(bp);
        if (bp->b_bcount > bp->b_bufsize)
                panic("bwrite");
        VOP_STRATEGY(bp);


@@ -193,22 +194,15 @@ bdwrite(bp)
 
        if ((bp->b_flags&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */
 
        if ((bp->b_flags&B_DELWRI) == 0)
                u.u_ru.ru_oublock++;            /* noone paid yet */

-#ifdef notdef

        /*
        /*

-        * This does not work for buffers associated with
-        * vnodes that are remote - they have no dev.
-        * Besides, we don't use bio with tapes, so rather
-        * than develop a fix, we just ifdef this out for now.
+        * If this is a tape drive, the write must be initiated.

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

-       else {
+       } else {

                bp->b_flags |= B_DELWRI | B_DONE;
                brelse(bp);
        }
                bp->b_flags |= B_DELWRI | B_DONE;
                brelse(bp);
        }

-#endif
-       bp->b_flags |= B_DELWRI | B_DONE;
-       brelse(bp);

 }
 
 /*
 }
 
 /*


@@ -232,10 +226,10 @@ brelse(bp)
        register s;
 
        trace(TR_BRELSE,
        register s;
 
        trace(TR_BRELSE,

-           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_blkno);
+           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_lblkno);

        /*
        /*

-        * If someone's waiting for the buffer, or
-        * is waiting for a buffer wake 'em up.
+        * If a process is waiting for the buffer, or
+        * is waiting for a free buffer, awaken it.

         */
        if (bp->b_flags&B_WANTED)
                wakeup((caddr_t)bp);
         */
        if (bp->b_flags&B_WANTED)
                wakeup((caddr_t)bp);


@@ -243,15 +237,22 @@ brelse(bp)
                bfreelist[0].b_flags &= ~B_WANTED;
                wakeup((caddr_t)bfreelist);
        }
                bfreelist[0].b_flags &= ~B_WANTED;
                wakeup((caddr_t)bfreelist);
        }

-       if (bp->b_flags & B_NOCACHE) {
+       /*
+        * Retry I/O for locked buffers rather than invalidating them.
+        */
+       if ((bp->b_flags & B_ERROR) && (bp->b_flags & B_LOCKED))
+               bp->b_flags &= ~B_ERROR;
+
+       /*
+        * Disassociate buffers that are no longer valid.
+        */
+       if (bp->b_flags & (B_NOCACHE|B_ERROR))

                bp->b_flags |= B_INVAL;
                bp->b_flags |= B_INVAL;

+       if ((bp->b_bufsize <= 0) || (bp->b_flags & (B_ERROR|B_INVAL))) {
+               if (bp->b_vp)
+                       brelvp(bp);
+               bp->b_flags &= ~B_DELWRI;

        }
        }

-       if (bp->b_flags&B_ERROR)
-               if (bp->b_flags & B_LOCKED)
-                       bp->b_flags &= ~B_ERROR;        /* try again later */
-               else
-                       brelvp(bp);                     /* no assoc */
-

        /*
         * Stick the buffer back on a free list.
         */
        /*
         * Stick the buffer back on a free list.
         */


@@ -290,12 +291,15 @@ incore(vp, blkno)
 
        dp = BUFHASH(vp, blkno);
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)
 
        dp = BUFHASH(vp, blkno);
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw)

-               if (bp->b_blkno == blkno && bp->b_vp == vp &&
+               if (bp->b_lblkno == blkno && bp->b_vp == vp &&

                    (bp->b_flags & B_INVAL) == 0)
                        return (1);
        return (0);
 }
 
                    (bp->b_flags & B_INVAL) == 0)
                        return (1);
        return (0);
 }
 

+/*
+ * Return a block if it is in memory.
+ */

 baddr(vp, blkno, size, cred, bpp)
        struct vnode *vp;
        daddr_t blkno;
 baddr(vp, blkno, size, cred, bpp)
        struct vnode *vp;
        daddr_t blkno;


@@ -319,13 +323,6 @@ baddr(vp, blkno, size, cred, bpp)
  * 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.
  * 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.


@@ -354,9 +351,13 @@ getblk(vp, blkno, size)
         * 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
         * 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

+        *
+        * Make it a panic to see if it ever really happens. mkm 11/89

         */
         */

-       if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-DEV_BSHIFT))
+       if ((unsigned)blkno >= 1 << (sizeof(int)*NBBY-DEV_BSHIFT)) {
+               panic("getblk: blkno too big");

                blkno = 1 << ((sizeof(int)*NBBY-DEV_BSHIFT) + 1);
                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


@@ -365,7 +366,7 @@ getblk(vp, blkno, size)
        dp = BUFHASH(vp, blkno);
 loop:
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
        dp = BUFHASH(vp, blkno);
 loop:
        for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {

-               if (bp->b_blkno != blkno || bp->b_vp != vp ||
+               if (bp->b_lblkno != blkno || bp->b_vp != vp ||

                    bp->b_flags&B_INVAL)
                        continue;
                s = splbio();
                    bp->b_flags&B_INVAL)
                        continue;
                s = splbio();


@@ -378,27 +379,19 @@ loop:
                splx(s);
                notavail(bp);
                if (bp->b_bcount != size) {
                splx(s);
                notavail(bp);
                if (bp->b_bcount != size) {

-                       if (bp->b_bcount < size && (bp->b_flags&B_DELWRI)) {
-                               bp->b_flags &= ~B_ASYNC;
-                               (void) bwrite(bp);
-                               goto loop;
-                       }
-                       if (brealloc(bp, size) == 0)
-                               goto loop;
-               }
-               if (bp->b_bcount != size && brealloc(bp, size) == 0)
+                       printf("getblk: stray size");
+                       bp->b_flags |= B_INVAL;
+                       bwrite(bp);

                        goto loop;
                        goto loop;

+               }

                bp->b_flags |= B_CACHE;
                return (bp);
        }
        bp = getnewbuf();
        bfree(bp);
        bremhash(bp);
                bp->b_flags |= B_CACHE;
                return (bp);
        }
        bp = getnewbuf();
        bfree(bp);
        bremhash(bp);

-       if (bp->b_vp)
-               brelvp(bp);
-       VREF(vp);
-       bp->b_vp = vp;
-       bp->b_dev = vp->v_rdev;
+       bgetvp(vp, bp);
+       bp->b_lblkno = blkno;

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


@@ -406,8 +399,7 @@ loop:
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, dp);
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, dp);

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

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


@@ -423,27 +415,23 @@ geteblk(size)
 
        if (size > MAXBSIZE)
                panic("geteblk: size too big");
 
        if (size > MAXBSIZE)
                panic("geteblk: size too big");

-loop:

        bp = getnewbuf();
        bp->b_flags |= B_INVAL;
        bfree(bp);
        bremhash(bp);
        flist = &bfreelist[BQ_AGE];
        bp = getnewbuf();
        bp->b_flags |= B_INVAL;
        bfree(bp);
        bremhash(bp);
        flist = &bfreelist[BQ_AGE];

-       brelvp(bp);

 #ifdef SECSIZE
        bp->b_blksize = DEV_BSIZE;
 #endif SECSIZE
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, flist);
 #ifdef SECSIZE
        bp->b_blksize = DEV_BSIZE;
 #endif SECSIZE
        bp->b_error = 0;
        bp->b_resid = 0;
        binshash(bp, flist);

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

        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;


@@ -454,72 +442,9 @@ brealloc(bp, size)
        struct buf *dp;
        int s;
 
        struct buf *dp;
        int s;
 

-       /*
-        * First need to make sure that all overlapping previous I/O
-        * is dispatched with.
-        */

        if (size == bp->b_bcount)
        if (size == bp->b_bcount)

-               return (1);
-       if (size < bp->b_bcount) { 
-               if (bp->b_flags & B_DELWRI) {
-                       (void) bwrite(bp);
-                       return (0);
-               }
-               if (bp->b_flags & B_LOCKED)
-                       panic("brealloc");
-               return (allocbuf(bp, size));
-       }
-       bp->b_flags &= ~B_DONE;
-       if (bp->b_vp == (struct vnode *)0)
-               return (allocbuf(bp, size));
-
-       trace(TR_BREALLOC,
-           pack(bp->b_vp->v_mount->m_fsid[0], 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_vp, bp->b_blkno);
-loop:
-       for (ep = dp->b_forw; ep != dp; ep = ep->b_forw) {
-               if (ep == bp || ep->b_vp != bp->b_vp ||
-                   (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;
-               }
-               splx(s);
-               notavail(ep);
-               if (ep->b_flags & B_DELWRI) {
-                       (void) bwrite(ep);
-                       goto loop;
-               }
-               ep->b_flags |= B_INVAL;
-               brelse(ep);
-       }
-       return (allocbuf(bp, size));
+               return;
+       allocbuf(bp, size);

 }
 
 /*
 }
 
 /*


@@ -553,8 +478,9 @@ loop:
                goto loop;
        }
        trace(TR_BRELSE,
                goto loop;
        }
        trace(TR_BRELSE,

-           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_blkno);
-       brelvp(bp);
+           pack(bp->b_vp->v_mount->m_fsid[0], bp->b_bufsize), bp->b_lblkno);
+       if (bp->b_vp)
+               brelvp(bp);

        if (bp->b_rcred != NOCRED) {
                cred = bp->b_rcred;
                bp->b_rcred = NOCRED;
        if (bp->b_rcred != NOCRED) {
                cred = bp->b_rcred;
                bp->b_rcred = NOCRED;


@@ -624,7 +550,7 @@ biodone(bp)
 /*
  * Ensure that no part of a specified block is in an incore buffer.
 #ifdef SECSIZE
 /*
  * Ensure 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).
+ * "size" is given in device blocks (the units of b_lblkno).

 #endif SECSIZE
 #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).


@@ -661,8 +587,8 @@ loop:
                        if (ep->b_vp != vp || (ep->b_flags & B_INVAL))
                                continue;
                        /* look for overlap */
                        if (ep->b_vp != vp || (ep->b_flags & B_INVAL))
                                continue;
                        /* look for overlap */

-                       if (ep->b_bcount == 0 || ep->b_blkno > ecurblk ||
-                           ep->b_blkno + btodb(ep->b_bcount) <= curblk)
+                       if (ep->b_bcount == 0 || ep->b_lblkno > ecurblk ||
+                           ep->b_lblkno + btodb(ep->b_bcount) <= curblk)

                                continue;
                        s = splbio();
                        if (ep->b_flags&B_BUSY) {
                                continue;
                        s = splbio();
                        if (ep->b_flags&B_BUSY) {


@@ -688,92 +614,213 @@ loop:
  * Make sure all write-behind blocks associated
  * with mount point are flushed out (from sync).
  */
  * Make sure all write-behind blocks associated
  * with mount point are flushed out (from sync).
  */

-bflush(mountp)
+mntflushbuf(mountp, flags)

        struct mount *mountp;
        struct mount *mountp;

+       int flags;

 {
 {

-       register struct buf *bp;

        register struct vnode *vp;
        register struct vnode *vp;

-       register struct buf *flist;
+
+loop:
+       for (vp = mountp->m_mounth; vp; vp = vp->v_mountf) {
+               if (vget(vp))
+                       goto loop;
+               vflushbuf(vp, flags);
+               vput(vp);
+       }
+}
+
+/*
+ * Flush all dirty buffers associated with a vnode.
+ */
+vflushbuf(vp, flags)
+       register struct vnode *vp;
+       int flags;
+{
+       register struct buf *bp;
+       struct buf *nbp;

        int s;
 
 loop:
        s = splbio();
        int s;
 
 loop:
        s = splbio();

-       for (flist = bfreelist; flist < &bfreelist[BQ_EMPTY]; flist++) {
-               for (bp = flist->av_forw; bp != flist; bp = bp->av_forw) {
-                       if ((bp->b_flags & B_BUSY))
-                               continue;
-                       if ((bp->b_flags & B_DELWRI) == 0)
-                               continue;
-                       if ((vp = bp->b_vp) == NULL)
-                               continue;
-                       if (vp->v_mount == mountp ||
-                           (vp->v_type == VBLK && vp->v_mounton == mountp)) {
-                               splx(s);
-                               notavail(bp);
-                               (void) bawrite(bp);
-                               goto loop;
-                       }
+       for (bp = vp->v_blockh; bp; bp = nbp) {
+               nbp = bp->b_blockf;
+               if ((bp->b_flags & B_BUSY))
+                       continue;
+               if ((bp->b_flags & B_DELWRI) == 0)
+                       continue;
+               splx(s);
+               notavail(bp);
+               (void) bawrite(bp);
+               goto loop;
+       }
+       if ((flags & B_SYNC) == 0)
+               return;
+wloop:
+       s = splbio();
+       for (bp = vp->v_blockh; bp; bp = nbp) {
+               nbp = bp->b_blockf;
+               if (bp->b_flags & B_BUSY) {
+                       bp->b_flags |= B_WANTED;
+                       sleep((caddr_t)bp, PRIBIO+1);
+                       splx(s);
+                       goto wloop;

                }
                }

+               if ((bp->b_flags & B_DELWRI))
+                       goto loop;

        }
        }

-       splx(s);

 }
 
 /*
  * Invalidate in core blocks belonging to closed or umounted filesystem
  *
 }
 
 /*
  * Invalidate in core blocks belonging to closed or umounted filesystem
  *

- * We walk through the buffer pool and invalidate any buffers for the
- * indicated mount point. Normally this routine is preceeded by a bflush
- * call, so that on a quiescent filesystem there will be no dirty
- * buffers when we are done. We return the count of dirty buffers when
- * we are finished.
+ * Go through the list of vnodes associated with the file system;
+ * for each vnode invalidate any buffers that it holds. Normally
+ * this routine is preceeded by a bflush call, so that on a quiescent
+ * filesystem there will be no dirty buffers when we are done. Binval
+ * returns the count of dirty buffers when it is finished.

  */
  */

-binval(mountp)
+mntinvalbuf(mountp)

        struct mount *mountp;
 {
        struct mount *mountp;
 {

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

        register struct vnode *vp;
        register struct vnode *vp;

+       int dirty = 0;
+
+loop:
+       for (vp = mountp->m_mounth; vp; vp = vp->v_mountf) {
+               if (vget(vp))
+                       goto loop;
+               dirty += vinvalbuf(vp, 1);
+               vput(vp);
+       }
+       return (dirty);
+}
+
+/*
+ * Flush out and invalidate all buffers associated with a vnode.
+ * Called with the underlying object locked.
+ */
+vinvalbuf(vp, save)
+       register struct vnode *vp;
+       int save;
+{
+       register struct buf *bp;
+       struct buf *nbp;

        int s, dirty = 0;
        int s, dirty = 0;

-#define dp ((struct buf *)hp)

 
 loop:
 
 loop:

-       for (hp = bufhash; hp < &bufhash[BUFHSZ]; hp++) {
-               for (bp = dp->b_forw; bp != dp; bp = bp->b_forw) {
-                       if ((vp = bp->b_vp) == NULL)
-                               continue;
-                       if (vp->v_mount != mountp &&
-                           (vp->v_type != VBLK || vp->v_mounton != mountp))
-                               continue;
-                       s = splbio();
-                       if (bp->b_flags & B_BUSY) {
-                               bp->b_flags |= B_WANTED;
-                               sleep((caddr_t)bp, PRIBIO+1);
-                               splx(s);
-                               goto loop;
-                       }
+       for (bp = vp->v_blockh; bp; bp = nbp) {
+               nbp = bp->b_blockf;
+               s = splbio();
+               if (bp->b_flags & B_BUSY) {
+                       bp->b_flags |= B_WANTED;
+                       sleep((caddr_t)bp, PRIBIO+1);

                        splx(s);
                        splx(s);

-                       notavail(bp);
+                       goto loop;
+               }
+               splx(s);
+               notavail(bp);
+               if (save) {

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

-                               (void) bawrite(bp);

                                dirty++;
                                dirty++;

-                               continue;
+                               (void) bwrite(bp);
+                               goto loop;

                        }
                        }

-                       bp->b_flags |= B_INVAL;
-                       brelvp(bp);
-                       brelse(bp);

                }
                }

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

        }
        }

+       if (vp->v_blockh != 0)
+               panic("vinvalbuf: flush failed");

        return (dirty);
 }
 
        return (dirty);
 }
 

+/*
+ * Associate a buffer with a vnode.
+ */
+bgetvp(vp, bp)
+       register struct vnode *vp;
+       register struct buf *bp;
+{
+
+       if (bp->b_vp)
+               panic("bgetvp: not free");
+       VREF(vp);
+       bp->b_vp = vp;
+       if (vp->v_type == VBLK || vp->v_type == VCHR)
+               bp->b_dev = vp->v_rdev;
+       else
+               bp->b_dev = NODEV;
+       /*
+        * Insert onto list for new vnode.
+        */
+       if (vp->v_blockh) {
+               bp->b_blockf = vp->v_blockh;
+               bp->b_blockb = &vp->v_blockh;
+               vp->v_blockh->b_blockb = &bp->b_blockf;
+               vp->v_blockh = bp;
+       } else {
+               vp->v_blockh = bp;
+               bp->b_blockb = &vp->v_blockh;
+               bp->b_blockf = NULL;
+       }
+}
+
+/*
+ * Disassociate a buffer from a vnode.
+ */

 brelvp(bp)
 brelvp(bp)

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

 {
 {

+       struct buf *bq;

        struct vnode *vp;
 
        if (bp->b_vp == (struct vnode *) 0)
        struct vnode *vp;
 
        if (bp->b_vp == (struct vnode *) 0)

-               return;
+               panic("brelvp: NULL");
+       /*
+        * Delete from old vnode list, if on one.
+        */
+       if (bp->b_blockb) {
+               if (bq = bp->b_blockf)
+                       bq->b_blockb = bp->b_blockb;
+               *bp->b_blockb = bq;
+               bp->b_blockf = NULL;
+               bp->b_blockb = NULL;
+       }

        vp = bp->b_vp;
        bp->b_vp = (struct vnode *) 0;
        vrele(vp);
 }
        vp = bp->b_vp;
        bp->b_vp = (struct vnode *) 0;
        vrele(vp);
 }

+
+/*
+ * Reassign a buffer from one vnode to another.
+ * Used to assign file specific control information
+ * (indirect blocks) to the vnode to which they belong.
+ */
+reassignbuf(bp, newvp)
+       register struct buf *bp;
+       register struct vnode *newvp;
+{
+       register struct buf *bq;
+
+       /*
+        * Delete from old vnode list, if on one.
+        */
+       if (bp->b_blockb) {
+               if (bq = bp->b_blockf)
+                       bq->b_blockb = bp->b_blockb;
+               *bp->b_blockb = bq;
+       }
+       /*
+        * Insert onto list for new vnode.
+        */
+       if (newvp->v_blockh) {
+               bp->b_blockf = newvp->v_blockh;
+               bp->b_blockb = &newvp->v_blockh;
+               newvp->v_blockh->b_blockb = &bp->b_blockf;
+               newvp->v_blockh = bp;
+       } else {
+               newvp->v_blockh = bp;
+               bp->b_blockb = &newvp->v_blockh;
+               bp->b_blockf = NULL;
+       }
+}