diff --git a/fs/udf/balloc.c b/fs/udf/balloc.c
index e48e9a3af76312d683723658ed42c51db7d8a740..1e068535b58bfc78b0970dc3ccb34e03cc7c1ecb 100644
--- a/fs/udf/balloc.c
+++ b/fs/udf/balloc.c
@@ -238,7 +238,7 @@ static int udf_bitmap_prealloc_blocks(struct super_block *sb,
 
 	mutex_lock(&sbi->s_alloc_mutex);
 	part_len = sbi->s_partmaps[partition].s_partition_len;
-	if (first_block < 0 || first_block >= part_len)
+	if (first_block >= part_len)
 		goto out;
 
 	if (first_block + block_count > part_len)
@@ -297,7 +297,7 @@ static int udf_bitmap_new_block(struct super_block *sb,
 	mutex_lock(&sbi->s_alloc_mutex);
 
 repeat:
-	if (goal < 0 || goal >= sbi->s_partmaps[partition].s_partition_len)
+	if (goal >= sbi->s_partmaps[partition].s_partition_len)
 		goal = 0;
 
 	nr_groups = bitmap->s_nr_groups;
@@ -666,8 +666,7 @@ static int udf_table_prealloc_blocks(struct super_block *sb,
 	int8_t etype = -1;
 	struct udf_inode_info *iinfo;
 
-	if (first_block < 0 ||
-		first_block >= sbi->s_partmaps[partition].s_partition_len)
+	if (first_block >= sbi->s_partmaps[partition].s_partition_len)
 		return 0;
 
 	iinfo = UDF_I(table);
@@ -743,7 +742,7 @@ static int udf_table_new_block(struct super_block *sb,
 		return newblock;
 
 	mutex_lock(&sbi->s_alloc_mutex);
-	if (goal < 0 || goal >= sbi->s_partmaps[partition].s_partition_len)
+	if (goal >= sbi->s_partmaps[partition].s_partition_len)
 		goal = 0;
 
 	/* We search for the closest matching block to goal. If we find
diff --git a/fs/udf/lowlevel.c b/fs/udf/lowlevel.c
index 703843f30ffd383f556639af7146c0d99a212c25..1b88fd5df05d6d7f6694a3d9284162d4ed386a0b 100644
--- a/fs/udf/lowlevel.c
+++ b/fs/udf/lowlevel.c
@@ -56,7 +56,12 @@ unsigned long udf_get_last_block(struct super_block *sb)
 	struct block_device *bdev = sb->s_bdev;
 	unsigned long lblock = 0;
 
-	if (ioctl_by_bdev(bdev, CDROM_LAST_WRITTEN, (unsigned long) &lblock))
+	/*
+	 * ioctl failed or returned obviously bogus value?
+	 * Try using the device size...
+	 */
+	if (ioctl_by_bdev(bdev, CDROM_LAST_WRITTEN, (unsigned long) &lblock) ||
+	    lblock == 0)
 		lblock = bdev->bd_inode->i_size >> sb->s_blocksize_bits;
 
 	if (lblock)