bcachefs: Handle backpointers with unknown data types

New data types might be added later, so we don't want to disallow
unknown data types - that'll be a compatibility hassle later. Instead,
ignore them.

Reported-by: syzbot+3a290f5ff67ca3023834@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index 8da1b68821a004026767b3d0fc127777c4387e5f..20c497f0c2cb4fe8cd36bbe42f3f6fb985aca22b 100644 (file)
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -784,7 +784,7 @@ enum alloc_sector_counter {
        ALLOC_SECTORS_NR
 };
 
-static enum alloc_sector_counter data_type_to_alloc_counter(enum bch_data_type t)
+static int data_type_to_alloc_counter(enum bch_data_type t)
 {
        switch (t) {
        case BCH_DATA_btree:
@@ -796,7 +796,7 @@ static enum alloc_sector_counter data_type_to_alloc_counter(enum bch_data_type t
        case BCH_DATA_parity:
                return ALLOC_stripe;
        default:
-               BUG();
+               return -1;
        }
 }
 
@@ -847,7 +847,11 @@ static int check_bucket_backpointer_mismatch(struct btree_trans *trans, struct b
                if (bp.v->bucket_gen != a->gen)
                        continue;
 
-               sectors[data_type_to_alloc_counter(bp.v->data_type)] += bp.v->bucket_len;
+               int alloc_counter = data_type_to_alloc_counter(bp.v->data_type);
+               if (alloc_counter < 0)
+                       continue;
+
+               sectors[alloc_counter] += bp.v->bucket_len;
        };
        bch2_trans_iter_exit(trans, &iter);
        if (ret)