-------- Original Message --------
Subject: Re: [PATCH] btrfs-progs: Check the consistence between the
parent node and child node/leaf.
From: Chris Mason <clm@xxxxxx>
To: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
Date: 2014年10月01日 23:49
On Fri, Sep 26, 2014 at 3:36 AM, Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
wrote:
When btrfs-progs walk down the tree, it does not check whether the child
node/leaf is valid.
In fact, there is some corrupted image whose csum is all valid but
parent node points to a invalid leaf.
In my case, the parent node in fs tree point to a invalid leaf(gen 11),
whose generation(15) and first key(EXTENT_TREE ROOT_ITEM 0) is
completely invalid, and will cause BUG_ON in process_inode_item().
Unfortunately, we are unable to fix when it happens.
So we can only output meaningful error message and avoid the insane
node/leaf, which is still much better than the original BUG_ON().
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
cmds-check.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/cmds-check.c b/cmds-check.c
index d479361..9471709 100644
--- a/cmds-check.c
+++ b/cmds-check.c
@@ -1302,6 +1302,52 @@ static void reada_walk_down(struct btrfs_root
*root,
}
}
+/*
+ * Check the child node/leaf by the following condition:
+ * 1. the first item key of the node/leaf should be the same with
the one
+ * in parent.
+ * 2. block in parent node should match the child node/leaf.
+ * 3. generation of parent node and child's header should be
consistent.
+ *
+ * Or the child node/leaf pointed by the key in parent is not valid.
+ *
+ * We hope to check leaf owner too, but since subvol may share leaves,
+ * which makes leaf owner check not so strong, key check should be
+ * sufficient enough for that case.
+ */
+static int check_child_node(struct btrfs_root *root,
+ struct extent_buffer *parent, int slot,
+ struct extent_buffer *child)
+{
+ struct btrfs_key parent_key;
+ struct btrfs_key child_key;
+ int ret = 0;
+
+ btrfs_item_key_to_cpu(parent, &parent_key, slot);
Dave mentioned he was getting a bunch of Wrong key of child node
messages from his current tree. I should have spotted it sooner, but
this call should be btrfs_node_key_to_cpu(), since the parent is
always a node.
+ btrfs_item_key_to_cpu(child, &child_key, 0);
This should check the level and only use btrfs_item_key_to_cpu on the
leaves.
Thanks!
-chris
Oh, that's completely right...
I forgot node and leaf should use different key to cpu func... :(
I'll fix it soon.
Thanks,
Qu
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