bcachefs: Try to print full btree error message

Metadata corruption bugs are hard to debug if we can't see exactly what
went wrong - try to allocate a bigger buffer so we can print out
everything we have.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_io.c

@@ -635,21 +635,26 @@ enum btree_validate_ret {
 ({									\
 	__label__ out;							\
 	char _buf[300];							\
+	char *buf2 = _buf;						\
 	struct printbuf out = PBUF(_buf);				\
 									\
+	buf2 = kmalloc(4096, GFP_ATOMIC);				\
+	if (buf2)							\
+		out = _PBUF(buf2, 4986);				\
+									\
 	btree_err_msg(&out, c, b, i, b->written, write);		\
 	pr_buf(&out, ": " msg, ##__VA_ARGS__);				\
 									\
 	if (type == BTREE_ERR_FIXABLE &&				\
 	    write == READ &&						\
 	    !test_bit(BCH_FS_INITIAL_GC_DONE, &c->flags)) {		\
-		mustfix_fsck_err(c, "%s", _buf);			\
+		mustfix_fsck_err(c, "%s", buf2);			\
 		goto out;						\
 	}								\
 									\
 	switch (write) {						\
 	case READ:							\
-		bch_err(c, "%s", _buf);					\
+		bch_err(c, "%s", buf2);					\
 									\
 		switch (type) {						\
 		case BTREE_ERR_FIXABLE:					\
@@ -670,7 +675,7 @@ enum btree_validate_ret {
 		}							\
 		break;							\
 	case WRITE:							\
-		bch_err(c, "corrupt metadata before write: %s", _buf);	\
+		bch_err(c, "corrupt metadata before write: %s", buf2);	\
 									\
 		if (bch2_fs_inconsistent(c)) {				\
 			ret = BCH_FSCK_ERRORS_NOT_FIXED;		\
@@ -679,6 +684,8 @@ enum btree_validate_ret {
 		break;							\
 	}								\
 out:									\
+	if (buf2 != _buf)						\
+		kfree(buf2);						\
 	true;								\
 })
 
@@ -844,7 +851,7 @@ static int validate_bset_keys(struct bch_fs *c, struct btree *b,
 
 			bch2_bkey_val_to_text(&PBUF(buf), c, u.s_c);
 			btree_err(BTREE_ERR_FIXABLE, c, b, i,
-				  "invalid bkey:\n%s\n%s", invalid, buf);
+				  "invalid bkey: %s\n%s", invalid, buf);
 
 			i->u64s = cpu_to_le16(le16_to_cpu(i->u64s) - k->u64s);
 			memmove_u64s_down(k, bkey_next(k),

fs/bcachefs/btree_iter.c

@@ -875,9 +875,19 @@ static void btree_iter_verify_new_node(struct btree_iter *iter, struct btree *b)
 		char buf[100];
 		struct bkey uk = bkey_unpack_key(b, k);
 
+		bch2_dump_btree_node(iter->trans->c, l->b);
 		bch2_bkey_to_text(&PBUF(buf), &uk);
-		panic("parent iter doesn't point to new node:\n%s\n%llu:%llu\n",
-		      buf, b->key.k.p.inode, b->key.k.p.offset);
+		panic("parent iter doesn't point to new node:\n"
+		      "iter pos %s %llu:%llu\n"
+		      "iter key %s\n"
+		      "new node %llu:%llu-%llu:%llu\n",
+		      bch2_btree_ids[iter->btree_id],
+		      iter->pos.inode,
+		      iter->pos.offset,
+		      buf,
+		      b->data->min_key.inode,
+		      b->data->min_key.offset,
+		      b->key.k.p.inode, b->key.k.p.offset);
 	}
 
 	if (!parent_locked)