On Mon, 2008-08-18 at 20:33 +0100, David Woodhouse wrote:
> On Mon, 2008-08-18 at 15:23 -0400, Chris Mason wrote:
> > The search key in Yan's patch changes to (u64)-1. We know that if
> > we're in slot 0, there's nothing after us in the tree.
>
> But because we searched for a reference to (u64)-1, the item we want is
> actually _earlier_ in the tree, not later.
>
Lets pretend I had put in commments something like the code below. The
important part is that directories have only one link, so they have only
one backref.
/*
* we're a directory and we have at most 1 back reference
* to our one and only parent directory
*/
if (namelen == 2 && strcmp(name, "..") == 0) {
struct btrfs_key key;
struct extent_buffer *leaf;
int slot;
key.objectid = dir->i_ino;
/* after the search, we'll be
* one slot after the last back reference for this
* inode.
*/
key.offset = (u64)-1;
btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
/* normally, I would check the return values after the
* search. But this time I merged the patch wrong and
* made a bug. If path->slots[0] == 0 after the
* search, there won't be any keys smaller to ours
* in the tree.
*/
if (ret < 0 || path->slots[0] == 0)
goto out_err;
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
BUG_ON(ret == 0);
ret = 0;
leaf = path->nodes[0];
/* go back one slot and find our only backref */
slot = path->slots[0] - 1;
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != dir->i_ino ||
key.type != BTRFS_INODE_REF_KEY) {
goto out_err;
}
location->objectid = key.offset;
location->type = BTRFS_INODE_ITEM_KEY;
location->offset = 0;
goto out;
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