Index: vfs_cluster.c
===================================================================
RCS file: /cvs/src/sys/kern/vfs_cluster.c,v
retrieving revision 1.17
diff -u -r1.17 vfs_cluster.c
--- vfs_cluster.c	5 Mar 2006 18:38:34 -0000	1.17
+++ vfs_cluster.c	7 Mar 2006 20:00:01 -0000
@@ -179,7 +179,7 @@
 				nblks = racluster;
 
 	    		error = VOP_BMAP(vp, lblkno, NULL,
-				&blkno, &ncontigafter, NULL);
+					 &blkno, &ncontigafter, NULL);
 			if (error)
 				goto single_block_read;
 			if (blkno == -1)
@@ -190,7 +190,7 @@
 				nblks = ncontigafter + 1;
 
 			bp = cluster_rbuild(vp, filesize, lblkno,
-				blkno, size, nblks, bp);
+					    blkno, size, nblks, bp);
 			lblkno += (bp->b_bufsize / size);
 		} else {
 single_block_read:
@@ -204,36 +204,46 @@
 	}
 
 	/*
-	 * if we have been doing sequential I/O, then do some read-ahead
+	 * If we have been doing sequential I/O, then do some read-ahead.
 	 */
 	rbp = NULL;
-	if (seqcount && (lblkno < (origblkno + seqcount))) {
-		/*
-		 * we now build the read-ahead buffer if it is desirable.
-		 */
-		if (((u_quad_t)(lblkno + 1) * size) <= filesize &&
-		    !(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) &&
-		    blkno != -1) {
+	if (seqcount &&
+	    lblkno < origblkno + seqcount &&
+	    (u_quad_t)(lblkno + 1) * size <= filesize
+	) {
+		rbp = getblk(vp, lblkno, size, 0, 0);
+		if ((rbp->b_flags & B_CACHE) == 0) {
 			int nblksread;
-			int ntoread = num_ra + 1;
+			int ntoread;
+
+			error = VOP_BMAP(vp, lblkno, NULL,
+					 &blkno, &num_ra, NULL);
+			if (error || blkno == (daddr_t)-1) {
+				rbp->b_flags &= ~(B_ASYNC | B_READ);
+				brelse(rbp);
+				rbp = NULL;
+				goto no_read_ahead;
+			}
+			ntoread = num_ra + 1;
 			nblksread = (origtotread + size - 1) / size;
 			if (seqcount < nblksread)
 				seqcount = nblksread;
 			if (seqcount < ntoread)
 				ntoread = seqcount;
+
+			rbp->b_flags |= B_READ | B_ASYNC | B_RAM;
 			if (num_ra) {
 				rbp = cluster_rbuild(vp, filesize, lblkno,
-					blkno, size, ntoread, NULL);
+						     blkno, size, ntoread, rbp);
 			} else {
-				rbp = getblk(vp, lblkno, size, 0, 0);
-				rbp->b_flags |= B_READ | B_ASYNC | B_RAM;
 				rbp->b_bio2.bio_blkno = blkno;
 			}
 		}
 	}
+no_read_ahead:
 
 	/*
-	 * handle the synchronous read
+	 * Handle the synchronous read
 	 */
 	if (bp) {
 #if defined(CLUSTERDEBUG)
@@ -252,7 +262,7 @@
 	}
 
 	/*
-	 * and if we have read-aheads, do them too
+	 * And if we have read-aheads, do them too
 	 */
 	if (rbp) {
 		if (error) {
@@ -316,16 +326,8 @@
 		--run;
 	}
 
-	if (fbp) {
-		tbp = fbp;
-		tbp->b_flags |= B_READ; 
-	} else {
-		tbp = getblk(vp, lbn, size, 0, 0);
-		if (tbp->b_flags & B_CACHE)
-			return tbp;
-		tbp->b_flags |= B_ASYNC | B_READ | B_RAM;
-	}
-
+	tbp = fbp;
+	tbp->b_flags |= B_READ; 
 	tbp->b_bio2.bio_blkno = blkno;
 	if( (tbp->b_flags & B_MALLOC) ||
 		((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
@@ -420,7 +422,7 @@
 			/*
 			 * Set a read-ahead mark as appropriate
 			 */
-			if ((fbp && (i == 1)) || (i == (run - 1)))
+			if (i == 1 || i == (run - 1))
 				tbp->b_flags |= B_RAM;
 
 			/*