On Fri, Sep 14, 2012 at 02:58:03AM -0600, Liu Bo wrote:

While testing xfstests 068, I realized that

commit bd7de2c9a449e26a5493d918618eb20ae60d56bd
(Btrfs: fix deadlock with freeze and sync V2)

did not fix the bug yet, since someone might jump in between checking
running transaction and joining transaction, and we may still run into
deadlock between freeze and sync.

So IMO the safest and most efficient way is to check running transaction
in joining a transaction directly.

With this patch, I tested xfstests 068 for 120 times and it did not get
into deadlock at least here.

Ok I've come up with a different way to fix this one and I'm still trying to
reproduce the problem your 2nd patch talks about, but I've taken the other 3 and
pushed them to btrfs-next.  Thanks!

Josef