Mailing List Archive: [PATCH] devfs v123 available

[PATCH] devfs v123 available

Oct 9, 1999, 5:56 PM

Post #1 of 3 (258 views)

Hi, all. Version 123 of my devfs patch is now available from:
http://www.atnf.csiro.au/~rgooch/linux/kernel-patches.html
The devfs FAQ is also available here.
This is against 2.3.20. Highlights of this release:
- Ported to kernel 2.3.20
<FLAMEWAR NOTE>
I know some people are wondering why I've been silent. Well, I can't
be bothered going over the same old tired ground again. Pretty much
every point has been debated many times before.
Even many of the "technical" points raised are a mixture of FUD, myth
and ignorance. Or simply a lack of *careful* reading of the FAQ or
source. Just one simple example: Alex and Ted's assertion that devfs
can only be mounted once. Have a look around line 45 of the FAQ for
the facts.
So I'm not going to respond until I see something new, relevant and
technically sound. Assuming I don't miss it amidst the flames and
noise. Oh. And don't Cc me in this flamewar.
Finally, a small number of people (on both sides) have been abusive,
personal and insulting. I can't stop you, and it's not my place to
tell people what to do, but I'd rather you didn't do it. It helps
no-one.
</FLAMEWAR NOTE>
Regards,
Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca
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Re: [PATCH] devfs v123 available [ In reply to ]

viro at math

Oct 9, 1999, 10:14 PM

Post #2 of 3 (252 views)

Permalink

On Sat, 9 Oct 1999, Richard Gooch wrote:
[snip]
> Even many of the "technical" points raised are a mixture of FUD, myth
> and ignorance. Or simply a lack of *careful* reading of the FAQ or
> source. Just one simple example: Alex and Ted's assertion that devfs
> can only be mounted once. Have a look around line 45 of the FAQ for
> the facts.
Ted misread my posting. What I'm saying is that once you mounted it
several times you are in for races. You can forget about the dir->i_sem
protection, since the semaphore is associated with inode and you have
different inodes in different instances. _VFS_ is (ab)using the existence
of dir->i_sem serialization and it's part of the problem. You have to rely
on revalidate and I'ld recommend you to look at the namei.c::cached_lookup.
Notice the behaviour of dcache.c::d_invalidate on directory inodes.
BTW, the same thing goes for devfs_unregister() - order of invalidation
matters since you may block in between (i.e. big lock doesn't help).
Richard, stuff around ->d_aliases/d_invalidate()/->i_dentry/->i_count/iget()
is a large painful mess right now. Most of filesystems do not notice it,
but those who go for invalidation usage are stumbling into this mess.
Especially if they support links. Doubly so if they can be mounted several
times. It's a VFS problem compounded by several misuses of ->i_dentry that
block more-or-less obvious fixes. Sigh... The fact that i_sem is used for
dcache protection also doesn't help.
Could we please take it into email or on fsdevel?
Cheers,
Al
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Re: [PATCH] devfs v123 available [ In reply to ]

rgooch at ras

Oct 9, 1999, 10:37 PM

Post #3 of 3 (251 views)

Permalink

Alexander Viro writes:
> Could we please take it into email or on fsdevel?
Sure. I'll get back to you (privately) once I've had a chance to look.
Regards,
Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca
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