diff --git a/fs/reiserfs/bitmap.c b/fs/reiserfs/bitmap.c
index f09a6f6..16b331d 100644
--- a/fs/reiserfs/bitmap.c
+++ b/fs/reiserfs/bitmap.c
@@ -61,6 +61,7 @@
 int is_reusable(struct super_block *s, b_blocknr_t block, int bit_value)
 {
 	unsigned int bmap, offset;
+	unsigned int bmap_count = reiserfs_bmap_count(s);
 
 	if (block == 0 || block >= SB_BLOCK_COUNT(s)) {
 		reiserfs_warning(s,
@@ -76,25 +77,26 @@
 	if (unlikely(test_bit(REISERFS_OLD_FORMAT,
 			      &(REISERFS_SB(s)->s_properties)))) {
 		b_blocknr_t bmap1 = REISERFS_SB(s)->s_sbh->b_blocknr + 1;
-		if (block >= bmap1 && block <= bmap1 + SB_BMAP_NR(s)) {
+		if (block >= bmap1 &&
+		    block <= bmap1 + bmap_count) {
 			reiserfs_warning(s, "vs: 4019: is_reusable: "
 					 "bitmap block %lu(%u) can't be freed or reused",
-					 block, SB_BMAP_NR(s));
+					 block, bmap_count);
 			return 0;
 		}
 	} else {
 		if (offset == 0) {
 			reiserfs_warning(s, "vs: 4020: is_reusable: "
 					 "bitmap block %lu(%u) can't be freed or reused",
-					 block, SB_BMAP_NR(s));
+					 block, bmap_count);
 			return 0;
 		}
 	}
 
-	if (bmap >= SB_BMAP_NR(s)) {
+	if (bmap >= bmap_count) {
 		reiserfs_warning(s,
 				 "vs-4030: is_reusable: there is no so many bitmap blocks: "
-				 "block=%lu, bitmap_nr=%d", block, bmap);
+				 "block=%lu, bitmap_nr=%u", block, bmap);
 		return 0;
 	}
 
@@ -143,8 +145,8 @@
 
 	BUG_ON(!th->t_trans_id);
 
-	RFALSE(bmap_n >= SB_BMAP_NR(s), "Bitmap %d is out of range (0..%d)",
-	       bmap_n, SB_BMAP_NR(s) - 1);
+	RFALSE(bmap_n >= reiserfs_bmap_count(s), "Bitmap %u is out of "
+	       "range (0..%u)", bmap_n, reiserfs_bmap_count(s) - 1);
 	PROC_INFO_INC(s, scan_bitmap.bmap);
 /* this is unclear and lacks comments, explain how journal bitmaps
    work here for the reader.  Convey a sense of the design here. What
@@ -249,12 +251,12 @@
 	} else {
 		hash_in = (char *)(&id);
 		hash = keyed_hash(hash_in, 4);
-		bm = hash % SB_BMAP_NR(s);
+		bm = hash % reiserfs_bmap_count(s);
 		if (!bm)
 			bm = 1;
 	}
 	/* this can only be true when SB_BMAP_NR = 1 */
-	if (bm >= SB_BMAP_NR(s))
+	if (bm >= reiserfs_bmap_count(s))
 		bm = 0;
 	return bm;
 }
@@ -328,10 +330,10 @@
 
 	get_bit_address(s, *start, &bm, &off);
 	get_bit_address(s, finish, &end_bm, &end_off);
-	if (bm > SB_BMAP_NR(s))
+	if (bm > reiserfs_bmap_count(s))
 		return 0;
-	if (end_bm > SB_BMAP_NR(s))
-		end_bm = SB_BMAP_NR(s);
+	if (end_bm > reiserfs_bmap_count(s))
+		end_bm = reiserfs_bmap_count(s);
 
 	/* When the bitmap is more than 10% free, anyone can allocate.
 	 * When it's less than 10% free, only files that already use the
@@ -397,10 +399,12 @@
 
 	get_bit_address(s, block, &nr, &offset);
 
-	if (nr >= sb_bmap_nr(rs)) {
+	if (nr >= reiserfs_bmap_count(s)) {
 		reiserfs_warning(s, "vs-4075: reiserfs_free_block: "
-				 "block %lu is out of range on %s",
-				 block, reiserfs_bdevname(s));
+				 "block %lu is out of range on %s "
+				 "(nr=%u,max=%u)", block,
+				 reiserfs_bdevname(s), nr,
+				 reiserfs_bmap_count(s));
 		return;
 	}
 
@@ -1269,12 +1273,13 @@
 int reiserfs_init_bitmap_cache(struct super_block *sb)
 {
 	struct reiserfs_bitmap_info *bitmap;
+	unsigned int bmap_nr = reiserfs_bmap_count(sb);
 
-	bitmap = vmalloc(sizeof (*bitmap) * SB_BMAP_NR(sb));
+	bitmap = vmalloc(sizeof(*bitmap) * bmap_nr);
 	if (bitmap == NULL)
 		return -ENOMEM;
 
-	memset(bitmap, 0xff, sizeof(*bitmap) * SB_BMAP_NR(sb));
+	memset(bitmap, 0xff, sizeof(*bitmap) * bmap_nr);
 
 	SB_AP_BITMAP(sb) = bitmap;
 
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 0e30ba0..bb05a3e 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -240,7 +240,7 @@
 	if (jb->bitmaps == NULL)
 		return;
 
-	for (i = 0; i < SB_BMAP_NR(p_s_sb); i++) {
+	for (i = 0; i < reiserfs_bmap_count(p_s_sb); i++) {
 		if (jb->bitmaps[i]) {
 			free_bitmap_node(p_s_sb, jb->bitmaps[i]);
 			jb->bitmaps[i] = NULL;
@@ -2734,7 +2734,7 @@
 	journal->j_persistent_trans = 0;
 	if (reiserfs_allocate_list_bitmaps(p_s_sb,
 					   journal->j_list_bitmap,
-					   SB_BMAP_NR(p_s_sb)))
+					   reiserfs_bmap_count(p_s_sb)))
 		goto free_and_return;
 	allocate_bitmap_nodes(p_s_sb);
 
@@ -2742,7 +2742,7 @@
 	SB_JOURNAL_1st_RESERVED_BLOCK(p_s_sb) = (old_format ?
 						 REISERFS_OLD_DISK_OFFSET_IN_BYTES
 						 / p_s_sb->s_blocksize +
-						 SB_BMAP_NR(p_s_sb) +
+						 reiserfs_bmap_count(p_s_sb) +
 						 1 :
 						 REISERFS_DISK_OFFSET_IN_BYTES /
 						 p_s_sb->s_blocksize + 2);
diff --git a/fs/reiserfs/resize.c b/fs/reiserfs/resize.c
index 66f1cda..f71c394 100644
--- a/fs/reiserfs/resize.c
+++ b/fs/reiserfs/resize.c
@@ -61,7 +61,8 @@
 	}
 
 	/* count used bits in last bitmap block */
-	block_r = SB_BLOCK_COUNT(s) - (SB_BMAP_NR(s) - 1) * s->s_blocksize * 8;
+	block_r = SB_BLOCK_COUNT(s) -
+			(reiserfs_bmap_count(s) - 1) * s->s_blocksize * 8;
 
 	/* count bitmap blocks in new fs */
 	bmap_nr_new = block_count_new / (s->s_blocksize * 8);
@@ -73,7 +74,7 @@
 
 	/* save old values */
 	block_count = SB_BLOCK_COUNT(s);
-	bmap_nr = SB_BMAP_NR(s);
+	bmap_nr = reiserfs_bmap_count(s);
 
 	/* resizing of reiserfs bitmaps (journal and real), if needed */
 	if (bmap_nr_new > bmap_nr) {
@@ -200,7 +201,7 @@
 			   free_blocks + (block_count_new - block_count -
 					  (bmap_nr_new - bmap_nr)));
 	PUT_SB_BLOCK_COUNT(s, block_count_new);
-	PUT_SB_BMAP_NR(s, bmap_nr_new);
+	PUT_SB_BMAP_NR(s, bmap_would_wrap(bmap_nr_new) ? : bmap_nr_new);
 	s->s_dirt = 1;
 
 	journal_mark_dirty(&th, s, SB_BUFFER_WITH_SB(s));
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index b82897a..57adfe9 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1725,6 +1725,21 @@
 		set_sb_umount_state(rs, REISERFS_ERROR_FS);
 		set_sb_fs_state(rs, 0);
 
+		/* Clear out s_bmap_nr if it would wrap. We can handle this
+		 * case, but older revisions can't. This will cause the
+		 * file system to fail mount on those older implementations,
+		 * avoiding corruption. -jeffm */
+		if (bmap_would_wrap(reiserfs_bmap_count(s)) &&
+		    sb_bmap_nr(rs) != 0) {
+			reiserfs_warning(s, "super-2030: This file system "
+					"claims to use %u bitmap blocks in "
+					"its super block, but requires %u. "
+					"Clearing to zero.", sb_bmap_nr(rs),
+					reiserfs_bmap_count(s));
+
+			set_sb_bmap_nr(rs, 0);
+		}
+
 		if (old_format_only(s)) {
 			/* filesystem of format 3.5 either with standard or non-standard
 			   journal */