From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.de>
Subject: Re: [PATCH/RFC] fscache/cachefiles versus btrfs
Date: Fri, 10 Apr 2015 11:24:31 +1000
Message-ID: <20150410112431.0e9c337d@notabene.brown>
References: <20150409174916.5a2efef5@notabene.brown>
	<29536.1428571388@warthog.procyon.org.uk>
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Cc: linux-btrfs@vger.kernel.org, linux-cachefs@redhat.com,
	linux-fsdevel@vger.kernel.org
To: David Howells <dhowells@redhat.com>
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On Thu, 09 Apr 2015 10:23:08 +0100 David Howells <dhowells@redhat.com> wrot=
e:

> NeilBrown <neilb@suse.de> wrote:
>=20
> >  Is there a better way?  Could a better way be created?  Maybe
> >  SEEK_DATA_RELIABLE ??
>=20
> fiemap() maybe?
>=20
> > Also, if you do try to use fscache on btrfs with 3.19, then nothing gets
> > cached (as expected) and with a heavy load you can lose a race and get =
an
> > asserting fail in fscache_enqueue_operation
>=20
> Do you have the patches here applied?
>=20
> 	http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=
=3Dfscache-fixes
>=20

Do I don't.  I had looked through them and while they did seem to be
addressing similar sorts of races, nothing seems like an obvious match.
I haven't been able to reproduce the BUG_ON myself.  I only have a report
of it repeatedly affecting someone else:

  https://bugzilla.opensuse.org/show_bug.cgi?id=3D908706

I'll probably have to be happy with fixing usage on btrfs, and hope the oth=
er
bug is fixed already or doesn't become a problem.

Thanks,
NeilBrown

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