btrfs-progs: chunk-recovery: Fix a float point error

Fix a zero division causing chunk-recovery fail.

Also fix a typo "strpie_length" -> "stripe_length".

Reported-by: Scotty Edmonds <scotty@scottyedmonds.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

2 files changed, 23 insertions, 3 deletions

diff --git a/btrfsck.h b/btrfsck.h
index 0882a383..e16f52f5 100644
--- a/btrfsck.h
+++ b/btrfsck.h
@@ -142,6 +142,23 @@ static inline unsigned long btrfs_chunk_record_size(int num_stripes)
 }
 void free_chunk_cache_tree(struct cache_tree *chunk_cache);
 
+/*
+ * Function to check validation for num_stripes, or it can call
+ * float point error for 0 division
+ * return < 0 for invalid combination
+ * return 0 for valid combination
+ */
+static inline int check_num_stripes(u64 type, int num_stripes)
+{
+	if (num_stripes == 0)
+		return -1;
+	if (type & BTRFS_BLOCK_GROUP_RAID5 && num_stripes <= 1)
+		return -1;
+	if (type & BTRFS_BLOCK_GROUP_RAID6 && num_stripes <= 2)
+		return -1;
+	return 0;
+}
+
 u64 calc_stripe_length(u64 type, u64 length, int num_stripes);
 /* For block group tree */
 static inline void block_group_tree_init(struct block_group_tree *tree)
diff --git a/chunk-recover.c b/chunk-recover.c
index 0d4c8ffa..85dc1bca 100644
--- a/chunk-recover.c
+++ b/chunk-recover.c
@@ -1607,16 +1607,19 @@ static int btrfs_verify_device_extents(struct block_group_record *bg,
 				       struct list_head *devexts, int ndevexts)
 {
 	struct device_extent_record *devext;
-	u64 strpie_length;
+	u64 stripe_length;
 	int expected_num_stripes;
 
 	expected_num_stripes = calc_num_stripes(bg->flags);
 	if (expected_num_stripes && expected_num_stripes != ndevexts)
 		return 1;
 
-	strpie_length = calc_stripe_length(bg->flags, bg->offset, ndevexts);
+	if (check_num_stripes(bg->flags, ndevexts) < 0)
+		return 1;
+
+	stripe_length = calc_stripe_length(bg->flags, bg->offset, ndevexts);
 	list_for_each_entry(devext, devexts, chunk_list) {
-		if (devext->length != strpie_length)
+		if (devext->length != stripe_length)
 			return 1;
 	}
 	return 0;