On Fri, Nov 21, 2014 at 8:01 AM, Patrick Schmid <sch...@phys.ethz.ch>
wrote:
On 15.11.2014 00:47, Chris Mason wrote:
Ok, I think this is related to the new fair read/writer lock
implementation in the generic kernel code.
btrfs_clear_path_blocking()
will end up taking locks outside of the strict locking order the
rest
of Btrfs uses. This used to be fine because we hold the blocking
lock
while we do it, but with the new queued locks we're running into
trouble. We hit a similar bug earlier and I convinced myself the
problem was only with btrfs_next_leaf and our trylock. But it's a
bigger problem than I realized.
So for now I've changed btrfs_clear_path_blocking to honor the rules
and fixed up our trylock to make it faster.
I'm letting a test run on this patch over the weekend, since I don't
want any surprises with your backup farm.
-chris
Hi Chris
Here comes a short feedback.... I applied your patch (Fix lockups from
btrfs_clear_path_blocking) yesterday and my system survived this
night! ;-)
Thank you for the quick fix.
Great to hear, thanks for following up. I'm sending this to Linus for
the next 3.18 rc.
-chris
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