bcachefs: Check for nonce offset inconsistency in data_update path

We've rarely been seeing a nonce offset inconsistency that doesn't show
up in tests: this adds some extra verification code to the data update
path that prints out more relevant info when it occurs.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c
index 0771a6d880bf5e2e4efcbcc21d91d34b64160dd4..5ed66202c22654a71b79fde919f6dd425e472874 100644 (file)
--- a/fs/bcachefs/data_update.c
+++ b/fs/bcachefs/data_update.c
@@ -239,6 +239,34 @@ restart_drop_extra_replicas:
 
                next_pos = insert->k.p;
 
+               /*
+                * Check for nonce offset inconsistency:
+                * This is debug code - we've been seeing this bug rarely, and
+                * it's been hard to reproduce, so this should give us some more
+                * information when it does occur:
+                */
+               struct printbuf err = PRINTBUF;
+               int invalid = bch2_bkey_invalid(c, bkey_i_to_s_c(insert), __btree_node_type(0, m->btree_id), 0, &err);
+               printbuf_exit(&err);
+
+               if (invalid) {
+                       struct printbuf buf = PRINTBUF;
+
+                       prt_str(&buf, "about to insert invalid key in data update path");
+                       prt_str(&buf, "\nold: ");
+                       bch2_bkey_val_to_text(&buf, c, old);
+                       prt_str(&buf, "\nk:   ");
+                       bch2_bkey_val_to_text(&buf, c, k);
+                       prt_str(&buf, "\nnew: ");
+                       bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(insert));
+
+                       bch2_print_string_as_lines(KERN_ERR, buf.buf);
+                       printbuf_exit(&buf);
+
+                       bch2_fatal_error(c);
+                       goto out;
+               }
+
                ret =   bch2_insert_snapshot_whiteouts(trans, m->btree_id,
                                                k.k->p, bkey_start_pos(&insert->k)) ?:
                        bch2_insert_snapshot_whiteouts(trans, m->btree_id,