Refactor unmapped buffer address handling.

 - Use pointer assignment rather than a combination of pointers and
   flags to switch buffers between unmapped and mapped.  This eliminates
   multiple flags and generally simplifies the logic.
 - Eliminate b_saveaddr since it is only used with pager bufs which have
   their b_data re-initialized on each allocation.
 - Gather up some convenience routines in the buffer cache for
   manipulating buf space and buf malloc space.
 - Add an inline, buf_mapped(), to standardize checks around unmapped
   buffers.

In collaboration with: mlaier
Reviewed by:	kib
Tested by:	pho (many small revisions ago)
Sponsored by:	EMC / Isilon Storage Division

3 files changed, 10 insertions, 25 deletions

diff --git a/sys/ufs/ffs/ffs_rawread.c b/sys/ufs/ffs/ffs_rawread.c
index aaa052e..84fa0db 100644
--- a/sys/ufs/ffs/ffs_rawread.c
+++ b/sys/ufs/ffs/ffs_rawread.c
@@ -62,8 +62,7 @@ static int ffs_rawread_readahead(struct vnode *vp,
 				 off_t offset,
 				 size_t len,
 				 struct thread *td,
-				 struct buf *bp,
-				 caddr_t sa);
+				 struct buf *bp);
 static int ffs_rawread_main(struct vnode *vp,
 			    struct uio *uio);
 
@@ -190,8 +189,7 @@ ffs_rawread_readahead(struct vnode *vp,
 		      off_t offset,
 		      size_t len,
 		      struct thread *td,
-		      struct buf *bp,
-		      caddr_t sa)
+		      struct buf *bp)
 {
 	int error;
 	u_int iolen;
@@ -219,7 +217,6 @@ ffs_rawread_readahead(struct vnode *vp,
 	bp->b_iocmd = BIO_READ;
 	bp->b_iodone = bdone;
 	bp->b_data = udata;
-	bp->b_saveaddr = sa;
 	blockno = offset / bsize;
 	blockoff = (offset % bsize) / DEV_BSIZE;
 	if ((daddr_t) blockno != blockno) {
@@ -272,7 +269,6 @@ ffs_rawread_main(struct vnode *vp,
 {
 	int error, nerror;
 	struct buf *bp, *nbp, *tbp;
-	caddr_t sa, nsa, tsa;
 	u_int iolen;
 	int spl;
 	caddr_t udata;
@@ -295,18 +291,15 @@ ffs_rawread_main(struct vnode *vp,
 	
 	bp = NULL;
 	nbp = NULL;
-	sa = NULL;
-	nsa = NULL;
 	
 	while (resid > 0) {
 		
 		if (bp == NULL) { /* Setup first read */
 			/* XXX: Leave some bufs for swap */
 			bp = getpbuf(&ffsrawbufcnt);
-			sa = bp->b_data;
 			pbgetvp(vp, bp);
 			error = ffs_rawread_readahead(vp, udata, offset,
-						     resid, td, bp, sa);
+						     resid, td, bp);
 			if (error != 0)
 				break;
 			
@@ -317,7 +310,6 @@ ffs_rawread_main(struct vnode *vp,
 				else
 					nbp = NULL;
 				if (nbp != NULL) {
-					nsa = nbp->b_data;
 					pbgetvp(vp, nbp);
 					
 					nerror = ffs_rawread_readahead(vp, 
@@ -328,8 +320,7 @@ ffs_rawread_main(struct vnode *vp,
 								       resid -
 								       bp->b_bufsize,
 								       td,
-								       nbp,
-								       nsa);
+								       nbp);
 					if (nerror) {
 						pbrelvp(nbp);
 						relpbuf(nbp, &ffsrawbufcnt);
@@ -365,8 +356,7 @@ ffs_rawread_main(struct vnode *vp,
 						      offset,
 						      bp->b_bufsize - iolen,
 						      td,
-						      bp,
-						      sa);
+						      bp);
 			if (error != 0)
 				break;
 		} else if (nbp != NULL) { /* Complete read with readahead */
@@ -375,10 +365,6 @@ ffs_rawread_main(struct vnode *vp,
 			bp = nbp;
 			nbp = tbp;
 			
-			tsa = sa;
-			sa = nsa;
-			nsa = tsa;
-			
 			if (resid <= bp->b_bufsize) { /* No more readaheads */
 				pbrelvp(nbp);
 				relpbuf(nbp, &ffsrawbufcnt);
@@ -392,8 +378,7 @@ ffs_rawread_main(struct vnode *vp,
 							       resid -
 							       bp->b_bufsize,
 							       td,
-							       nbp,
-							       nsa);
+							       nbp);
 				if (nerror != 0) {
 					pbrelvp(nbp);
 					relpbuf(nbp, &ffsrawbufcnt);
@@ -404,7 +389,7 @@ ffs_rawread_main(struct vnode *vp,
 			break;		
 		}  else if (resid > 0) { /* More to read, no readahead */
 			error = ffs_rawread_readahead(vp, udata, offset,
-						      resid, td, bp, sa);
+						      resid, td, bp);
 			if (error != 0)
 				break;
 		}
diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index 1f59a86..ebd8520 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -2094,7 +2094,7 @@ ffs_bufwrite(struct buf *bp)
 		if (newbp == NULL)
 			goto normal_write;
 
-		KASSERT((bp->b_flags & B_UNMAPPED) == 0, ("Unmapped cg"));
+		KASSERT(buf_mapped(bp), ("Unmapped cg"));
 		memcpy(newbp->b_data, bp->b_data, bp->b_bufsize);
 		BO_LOCK(bp->b_bufobj);
 		bp->b_vflags |= BV_BKGRDINPROG;
diff --git a/sys/ufs/ffs/ffs_vnops.c b/sys/ufs/ffs/ffs_vnops.c
index 618ed8e..5a70e5c 100644
--- a/sys/ufs/ffs/ffs_vnops.c
+++ b/sys/ufs/ffs/ffs_vnops.c
@@ -581,7 +581,7 @@ ffs_read(ap)
 			xfersize = size;
 		}
 
-		if ((bp->b_flags & B_UNMAPPED) == 0) {
+		if (buf_mapped(bp)) {
 			error = vn_io_fault_uiomove((char *)bp->b_data +
 			    blkoffset, (int)xfersize, uio);
 		} else {
@@ -758,7 +758,7 @@ ffs_write(ap)
 		if (size < xfersize)
 			xfersize = size;
 
-		if ((bp->b_flags & B_UNMAPPED) == 0) {
+		if (buf_mapped(bp)) {
 			error = vn_io_fault_uiomove((char *)bp->b_data +
 			    blkoffset, (int)xfersize, uio);
 		} else {