From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:38771 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753970AbcINQWf (ORCPT ); Wed, 14 Sep 2016 12:22:35 -0400 From: Liu Bo To: linux-btrfs@vger.kernel.org Cc: David Sterba Subject: [PATCH] Btrfs: kill BUG_ON in do_relocation Date: Wed, 14 Sep 2016 09:27:47 -0700 Message-Id: <1473870467-18721-1-git-send-email-bo.li.liu@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: While updating btree, we try to push items between sibling nodes/leaves in order to keep height as low as possible. But we don't memset the original places with zero when pushing items so that we could end up leaving stale content in nodes/leaves. One may read the above stale content by increasing btree blocks' @nritems. One case I've come across is that in fs tree, a leaf has two parent nodes, hence running balance ends up with processing this leaf with two parent nodes, but it can only reach the valid parent node through btrfs_search_slot, so it'd be like, do_relocation for P in all parent nodes of block A: if !P->eb: btrfs_search_slot(key); --> get path from P to A. if lowest: BUG_ON(A->bytenr != bytenr of A recorded in P); btrfs_cow_block(P, A); --> change A's bytenr in P. After btrfs_cow_block, P has the new bytenr of A, but with the same @key, we get the same path again, and get panic by BUG_ON. Signed-off-by: Liu Bo --- fs/btrfs/relocation.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 680e234..bce8fea 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2723,7 +2723,14 @@ static int do_relocation(struct btrfs_trans_handle *trans, bytenr = btrfs_node_blockptr(upper->eb, slot); if (lowest) { - BUG_ON(bytenr != node->bytenr); + if (bytenr != node->bytenr) { + btrfs_err(root->fs_info, + "lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu", + bytenr, node->bytenr, slot, + upper->eb->start); + err = -EEXIST; + goto next; + } } else { if (node->eb->start == bytenr) goto next; -- 2.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-