From: David Sterba <dsterba@suse.cz>
To: Jeff Mahoney <jeffm@suse.com>
Cc: Anand Jain <anand.jain@oracle.com>, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v3] btrfs: fix a possible umount deadlock
Date: Mon, 3 Oct 2016 18:20:37 +0200 [thread overview]
Message-ID: <20161003162037.GB6576@suse.cz> (raw)
In-Reply-To: <b16b4d32-9990-25d3-2973-f2bae1e6fba5@suse.com>
On Thu, Sep 22, 2016 at 12:24:07PM -0400, Jeff Mahoney wrote:
> This isn't necessarily a comment on this code in particular, but what's
> the reason for using call_rcu to defer the freeing instead of
> synchronize_rcu and freeing the device directly via __free_device (if it
> accepted a btrfs_device)? It's a pattern that's used throughout
> volumes.c and it's old[1]. I'm not sure if it was intentional to defer
> freeing since that was actually a functional change from the code it
> replaced.
It could be unintentional, the patch was supposed to relax the read-only
side, ie. use RCU instead of mutex. Deferred freeing does not seem to be
necessary. The device locking code needs cleanup/refactoring.
prev parent reply other threads:[~2016-10-03 16:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-09 8:31 [PATCH] btrfs: fix a possible umount deadlock Anand Jain
2016-09-09 12:53 ` David Sterba
2016-09-09 23:08 ` Anand Jain
2016-09-09 23:03 ` [PATCH v2] " Anand Jain
2016-09-21 14:26 ` David Sterba
2016-09-22 4:59 ` Anand Jain
2016-09-22 4:56 ` [PATCH v3] " Anand Jain
2016-09-22 15:35 ` David Sterba
2016-09-22 16:24 ` Jeff Mahoney
2016-10-03 16:20 ` David Sterba [this message]
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