Re: reiser4: maybe just fix bugs?

From: David Masover
Date: Fri Aug 04 2006 - 17:07:16 EST

Theodore Tso wrote:
On Tue, Aug 01, 2006 at 11:55:57AM -0500, David Masover wrote:
If I understand it right, the original Reiser4 model of file metadata is the file-as-directory stuff that caused such a furor the last big push for inclusion (search for "Silent semantic changes in Reiser4"):

The furor was caused by concerns Al Viro expressed about
locking/deadlock issues that reiser4 introduced.

Which, I believe, was about file-as-dir. Which also had problems with things like directory loops. That's sort of a disk space memory leak.

The bigger issue with xattr support is two-fold. First of all, there
are the progams that are expecting the existing extended attribute


More importantly are the system-level extended attributes, such as
those used by SELINUX, which by definition are not supposed to be
visible to the user at all,

I don't see why either of these are issues. The SELINUX stuff can be a plugin which doesn't necessarily have a user-level interface. Cryptocompress, for instance, exists independent of its user-level interface (probably the file-as-dir stuff), and will probably be implemented in some sort of stable form as a system-wide default for new files.

So, certainly metadata (xattrs) as a plugin could be implemented with no UI at all, or any given UI.

... Anyway, I still see no reason why these cannot be implemented in Reiser4, other than the possibility that if it uses "plugins", I guarantee that at least one or two people will hate the implementation for that reason alone.

Not supporting xattrs means that those distro's that use SELINUX by
default (i.e., RHEL, Fedora, etc.) won't want to use reiser4, because
SELINUX won't work on reiser4 filesytstems.

Right. So they will be implemented, eventually.

Whether or not Hans cares about this is up to him....

He does, or he should. Reiser4 needs every bit of acceptance it can get right now, as long as it can get them without compromising its goals or philosophy. Extended attributes only compromise these because it provides less incentive to learn any other metadata interface that Reiser4 provides. But that's irrelevant if Reiser4 doesn't gain enough acceptance due to lack of xattr support, anything it has will be irrelevant anyway.

So just as we provide the standard interface to Unix permissions (even though we intend to implement things like acls and views, and even though there was a file/.pseudo/rwx interface), we should provide the standard xattr interface, and the standard direct IO interface, and anything else that's practical. Be a good, standard filesystem first, and an innovative filesystem second.
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