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); ?
-Eric
> + exit(1);
> + }
>
> signal_maskfunc(SIGCHLD, SIG_UNBLOCK);
> pthread_mutex_lock(&mainwait);
> --
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