BRT: Check bv_mos_entries in brt_entry_lookup()

When vdev first sees some block cloning, there is a window when brt_maybe_exists() might already return true since something was cloned, but bv_mos_entries is still 0 since BRT ZAP was not yet created. In such case we should not try to look into the ZAP and dereference NULL bv_mos_entries_dnode. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Rob Norris <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc. Closes #16851
openzfs · Dec 12, 2024 · 19a04e5 · 19a04e5
1 parent e0039c7
commit 19a04e5
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/module/zfs/brt.c b/module/zfs/brt.c
@@ -859,6 +859,9 @@ brt_entry_lookup(brt_vdev_t *brtvd, brt_entry_t *bre)
 {
 	uint64_t off = BRE_OFFSET(bre);
 
+	if (brtvd->bv_mos_entries == 0)
+		return (SET_ERROR(ENOENT));
+
 	return (zap_lookup_uint64_by_dnode(brtvd->bv_mos_entries_dnode,
 	    &off, BRT_KEY_WORDS, 1, sizeof (bre->bre_count), &bre->bre_count));
 }