On 11/16/17 10:48 PM, Darrick J. Wong wrote:
> 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?
Eh if there's precedent for such sloppiness, I guess we can stick with
V1. ;)
Thanks for checking.
-Eric
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