Re: nnull

["Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>]

Matthew Dillon wrote:

>     There is one issue with regards to overlayed namecache entries.
>     The issue occurs when you try to do a rename() or other namespace 
>     operation and you have multiple namecache records refering to the
>     same physical namespace.  Since rename() locks the namespace by locking
>     the related namecache records, it becomes possible for a namespace
>     operation in the nullfs layer to race a namespace operation in the
>     underlying filesystem layer.  The system probably wouldn't be too happy
>     when this happens.

Maybe a doubly linked list of/in the namecache entries.  Locking would 
always lock either just the first entry in the list (I think that's 
sufficient) or at least always obey the same order to prevent deadlocks. 
 This way renames to self (in another incarnation) can be detected as 
well (by running through the list).

cheers
  simon

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