Miklos Szeredi wrote:
> On Fri, 11 Jul 2008, Sage Weil wrote:
>> However, vfs_rename_dir() doesn't properly account for filesystems with
>> FS_RENAME_DOES_D_MOVE. If new_dentry has a target inode attached, it
>> unhashes the new_dentry prior to the rename() iop and rehashes it after,
>> but doesn't account for the possibility that rename() may have swapped
>> {old,new}_dentry. For FS_RENAME_DOES_D_MOVE filesystems, it rehashes
>> new_dentry (now the old renamed-from name, which d_move() expected to go
>> away), such that a subsequent lookup will find it.
>>
>> To correct this, move vfs_rename_dir()'s call to d_move() _before_ the
>> target inode mutex is dealt with. Since d_move() will have been called
>> for all filesystems at this point, there is no need to rehash new_dentry
>> unless the rename failed. (If the rename succeeded, old_dentry should
>> already be rehashed in the new location.)
>
> I think rehashing the new dentry is bogus, even on error.
So we'd just come back through lookup to repopulate the existing
destination name that vfs_rename_dir() unhashed before calling
->rename() in the case that the rename fails? That seems gross, but
relatively harmless.
> So a better fix would be just to remove the rehashing completely.
> Does the below patch work for you?
It'd work for my case, yeah.
- z
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