btrfs-progs: check: prevent attempt to insert extent record with max_size==0

When this happens, we will trip a BUG_ON(end < start) in insert_state
because in check_extent_refs, we use this max_size expecting it's not zero:

  set_extent_dirty(root->fs_info->excluded_extents,
                   rec->start,
                   rec->start + rec->max_size - 1);

See https://bugzilla.redhat.com/show_bug.cgi?id=1435567
for an example where this scenario occurs.

Signed-off-by: Christophe de Dinechin <dinechin@redhat.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/cmds-check.c b/cmds-check.c
index e825119..571bd4e 100644 (file)
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -6030,6 +6030,7 @@ static int add_extent_rec_nolookup(struct cache_tree *extent_cache,
        struct extent_record *rec;
        int ret = 0;
 
+       BUG_ON(tmpl->max_size == 0);
        rec = malloc(sizeof(*rec));
        if (!rec)
                return -ENOMEM;