1 files changed, 81 insertions, 17 deletions

diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index 377ad172d74..e7b2bafa1dd 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -69,9 +69,53 @@ struct ext2_group_desc * ext2_get_group_desc(struct super_block * sb,
 	return desc + offset;
 }
 
+static int ext2_valid_block_bitmap(struct super_block *sb,
+					struct ext2_group_desc *desc,
+					unsigned int block_group,
+					struct buffer_head *bh)
+{
+	ext2_grpblk_t offset;
+	ext2_grpblk_t next_zero_bit;
+	ext2_fsblk_t bitmap_blk;
+	ext2_fsblk_t group_first_block;
+
+	group_first_block = ext2_group_first_block_no(sb, block_group);
+
+	/* check whether block bitmap block number is set */
+	bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
+	offset = bitmap_blk - group_first_block;
+	if (!ext2_test_bit(offset, bh->b_data))
+		/* bad block bitmap */
+		goto err_out;
+
+	/* check whether the inode bitmap block number is set */
+	bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
+	offset = bitmap_blk - group_first_block;
+	if (!ext2_test_bit(offset, bh->b_data))
+		/* bad block bitmap */
+		goto err_out;
+
+	/* check whether the inode table block number is set */
+	bitmap_blk = le32_to_cpu(desc->bg_inode_table);
+	offset = bitmap_blk - group_first_block;
+	next_zero_bit = ext2_find_next_zero_bit(bh->b_data,
+				offset + EXT2_SB(sb)->s_itb_per_group,
+				offset);
+	if (next_zero_bit >= offset + EXT2_SB(sb)->s_itb_per_group)
+		/* good bitmap for inode tables */
+		return 1;
+
+err_out:
+	ext2_error(sb, __FUNCTION__,
+			"Invalid block bitmap - "
+			"block_group = %d, block = %lu",
+			block_group, bitmap_blk);
+	return 0;
+}
+
 /*
- * Read the bitmap for a given block_group, reading into the specified 
- * slot in the superblock's bitmap cache.
+ * Read the bitmap for a given block_group,and validate the
+ * bits for block/inode/inode tables are set in the bitmaps
  *
  * Return buffer_head on success or NULL in case of failure.
  */
@@ -80,17 +124,36 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group)
 {
 	struct ext2_group_desc * desc;
 	struct buffer_head * bh = NULL;
-	
-	desc = ext2_get_group_desc (sb, block_group, NULL);
+	ext2_fsblk_t bitmap_blk;
+
+	desc = ext2_get_group_desc(sb, block_group, NULL);
 	if (!desc)
-		goto error_out;
-	bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
-	if (!bh)
-		ext2_error (sb, "read_block_bitmap",
+		return NULL;
+	bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
+	bh = sb_getblk(sb, bitmap_blk);
+	if (unlikely(!bh)) {
+		ext2_error(sb, __FUNCTION__,
+			    "Cannot read block bitmap - "
+			    "block_group = %d, block_bitmap = %u",
+			    block_group, le32_to_cpu(desc->bg_block_bitmap));
+		return NULL;
+	}
+	if (likely(bh_uptodate_or_lock(bh)))
+		return bh;
+
+	if (bh_submit_read(bh) < 0) {
+		brelse(bh);
+		ext2_error(sb, __FUNCTION__,
 			    "Cannot read block bitmap - "
 			    "block_group = %d, block_bitmap = %u",
 			    block_group, le32_to_cpu(desc->bg_block_bitmap));
-error_out:
+		return NULL;
+	}
+	if (!ext2_valid_block_bitmap(sb, desc, block_group, bh)) {
+		brelse(bh);
+		return NULL;
+	}
+
 	return bh;
 }
 
@@ -474,11 +537,13 @@ do_more:
 	    in_range (block, le32_to_cpu(desc->bg_inode_table),
 		      sbi->s_itb_per_group) ||
 	    in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
-		      sbi->s_itb_per_group))
+		      sbi->s_itb_per_group)) {
 		ext2_error (sb, "ext2_free_blocks",
 			    "Freeing blocks in system zones - "
 			    "Block = %lu, count = %lu",
 			    block, count);
+		goto error_return;
+	}
 
 	for (i = 0, group_freed = 0; i < count; i++) {
 		if (!ext2_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
@@ -1250,8 +1315,8 @@ retry_alloc:
 	smp_rmb();
 
 	/*
-	 * Now search the rest of the groups.  We assume that 
-	 * i and gdp correctly point to the last group visited.
+	 * Now search the rest of the groups.  We assume that
+	 * group_no and gdp correctly point to the last group visited.
 	 */
 	for (bgi = 0; bgi < ngroups; bgi++) {
 		group_no++;
@@ -1311,11 +1376,13 @@ allocated:
 	    in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
 		      EXT2_SB(sb)->s_itb_per_group) ||
 	    in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
-		      EXT2_SB(sb)->s_itb_per_group))
+		      EXT2_SB(sb)->s_itb_per_group)) {
 		ext2_error(sb, "ext2_new_blocks",
 			    "Allocating block in system zone - "
 			    "blocks from "E2FSBLK", length %lu",
 			    ret_block, num);
+		goto out;
+	}
 
 	performed_allocation = 1;
 
@@ -1466,9 +1533,6 @@ int ext2_bg_has_super(struct super_block *sb, int group)
  */
 unsigned long ext2_bg_num_gdb(struct super_block *sb, int group)
 {
-	if (EXT2_HAS_RO_COMPAT_FEATURE(sb,EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
-	    !ext2_group_sparse(group))
-		return 0;
-	return EXT2_SB(sb)->s_gdb_count;
+	return ext2_bg_has_super(sb, group) ? EXT2_SB(sb)->s_gdb_count : 0;
 }