Re: what is necessary for directory hard links

From: Horst H. von Brand
Date: Fri Jul 21 2006 - 14:55:10 EST

Joshua Hudson <joshudson@xxxxxxxxx> wrote:
> This patch is the sum total of all that I had to change in the kernel
> VFS layer to support hard links to directories

Can't be done, as it creates the possibility of loops. The "only files can
be hardlinked" idea makes garbage collection (== deleting of unreachable
objects) simple: Just check the number of references.

Detecting unconnected subgraphs uses a /lot/ of memory; and much worse, you
have to stop (almost) all filesystem activity while doing it.

Besides, the flow "root down through directories" gives a natural order in
which to go locking stuff when needed; if there can be loops, the system
could easily deadlock.
Dr. Horst H. von Brand User #22616
Departamento de Informatica Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria +56 32 654239
Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at