On Thu, Nov 16, 2017 at 07:45:09PM -0800, Darrick J. Wong wrote:
> On Thu, Nov 16, 2017 at 03:10:39PM -0600, Eric Sandeen wrote:
> >
> >
> > On 11/15/17 7:14 PM, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > >
> > > If xfs_copy is told to copy a filesystem and /all/ the writer threads
> > > hit an write error, there won't be any threads to unlock mainwait, which
> > > means that write_wbuf will deadlock with itself trying to lock mainwait.
> > > Therefore, if we discover that all the writer threads are dead, just
> > > bail out.
> > >
> > > Discovered by running xfs/073 with a tiny test device.
> > >
> > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > > ---
> > > copy/xfs_copy.c | 12 ++++++++++++
> > > 1 file changed, 12 insertions(+)
> > >
> > > diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c
> > > index 33e05df..fb37375 100644
> > > --- a/copy/xfs_copy.c
> > > +++ b/copy/xfs_copy.c
> > > @@ -476,6 +476,7 @@ void
> > > write_wbuf(void)
> > > {
> > > int i;
> > > + int badness = 0;
> > >
> > > /* verify target threads */
> > > for (i = 0; i < num_targets; i++)
> > > @@ -486,6 +487,17 @@ write_wbuf(void)
> > > for (i = 0; i < num_targets; i++)
> > > if (target[i].state != INACTIVE)
> > > pthread_mutex_unlock(&targ[i].wait); /* wake up */
> > > + else
> > > + badness++;
> > > +
> > > + /*
> > > + * If all the targets are inactive then there won't be any io
> > > + * threads left to release mainwait. We're screwed, so bail out.
> > > + */
> > > + if (badness == num_targets) {
> > > + check_errors();
> >
> > libxfs_umount(mp); ?
>
> Doh. v2 on its way
Hmmm. The other error bailouts don't call libxfs_umount and it hardly
matters since we're exiting anyway. The mp is a local variable to main
so we'd have to convey abort status out of write_wbuf back to main.
That's a bigger change; do you want me to pursue that instead?
--D
> --D
>
> > -Eric
> >
> > > + exit(1);
> > > + }
> > >
> > > signal_maskfunc(SIGCHLD, SIG_UNBLOCK);
> > > pthread_mutex_lock(&mainwait);
> > > --
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