double close strikes panic if md attaching a corrupt file

[Csaba Henk]

On Fri, Nov 25, 2005 at 09:56:20PM -0500, Kris Kennaway wrote:
> > I attach two patches, they realize the above ideas, respectively.
> > Note that I didn't test either.
> 
> You probably should do so ;-) This isn't the easiest thing for someone
> to test without such corrupted media.

Umm... I was hoping that someone in the list will suggest a way for
easily creating corrupt files. As I don't have a corrupt media, either
:)

I picked this when Fuse was panicking upon md attaching from a Fuse
based filesystem, cf.

http://lists.freebsd.org/pipermail/freebsd-ports/2005-November/027724.html

The fuse module didn't implement VOP_READ (it rather used a file level
"fo_read" method), hence from the point of the md code all files under a
Fuse filesystem seem corrupt. So this was triggered. (Since then I added
the VOP_READ, btw.)

If I test the proposed fixes with a VOP_READ-less fuse module and they
will save me from the panic (and work well on traditional fs-es), will
you say it's OK? The fuse module lacks a proper audit from "serious"
people, so you could dismiss it as well, saying you can't be sure that
the problem is not with Fuse...

Btw, if you said yes, that means you can as well easily get at a fine
"corrupt media" :)

Csaba