From: Jan Kara <jack@suse.cz>
To: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Jan Kara <jack@suse.cz>, Brown Neil <neilb@suse.de>,
Viro Alexander <viro@zeniv.linux.org.uk>,
NFS <linux-nfs@vger.kernel.org>
Subject: Re: NFS deadlock between 'sync' and commit after unmount....
Date: Tue, 8 Apr 2014 00:32:09 +0200 [thread overview]
Message-ID: <20140407223209.GA1125@quack.suse.cz> (raw)
In-Reply-To: <1396908542.5563.12.camel@leira.trondhjem.org>
On Mon 07-04-14 18:09:02, Trond Myklebust wrote:
> On Mon, 2014-04-07 at 22:27 +0200, Jan Kara wrote:
> > Hello,
> >
> > On Mon 07-04-14 10:10:27, Trond Myklebust wrote:
>
> > > The problem seems to be the use of iterate_supers(), which grabs a
> > > passive reference, and conflicts with our use of an active reference in
> > > the open context.
> > Yeah, we cannot really do otherwise in iterate_supers() - we have to grab
> > some superblock reference and we don't really want to get an active one
> > since that would result in spurious EBUSY returns from umount.
>
> BTW: By what mechanism does an active reference lead to EBUSY issues
> here?
Ah, sorry. I was wrong. We use mount usecount for this. But still using
active reference for iterate_supers() seems wrong as that could result in
handling of destruction of superblock from it...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
prev parent reply other threads:[~2014-04-07 22:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-07 3:50 NFS deadlock between 'sync' and commit after unmount NeilBrown
2014-04-07 14:10 ` Trond Myklebust
2014-04-07 20:27 ` Jan Kara
2014-04-07 22:02 ` Trond Myklebust
2014-04-07 22:35 ` Jan Kara
2014-04-07 23:07 ` Trond Myklebust
2014-04-10 21:25 ` Jan Kara
2014-04-07 22:09 ` Trond Myklebust
2014-04-07 22:32 ` Jan Kara [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140407223209.GA1125@quack.suse.cz \
--to=jack@suse.cz \
--cc=linux-nfs@vger.kernel.org \
--cc=neilb@suse.de \
--cc=trond.myklebust@primarydata.com \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).