On Tue, Jun 11, 2019 at 11:49:02PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Create a pwork destroy function that uses polling instead of
> uninterruptible sleep to wait for work items to finish so that we can
> touch the softlockup watchdog. IOWs, gross hack.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_iwalk.c | 3 +++
> fs/xfs/xfs_iwalk.h | 3 ++-
> fs/xfs/xfs_pwork.c | 19 +++++++++++++++++++
> fs/xfs/xfs_pwork.h | 3 +++
> fs/xfs/xfs_qm.c | 2 +-
> 5 files changed, 28 insertions(+), 2 deletions(-)
>
>
...
> diff --git a/fs/xfs/xfs_pwork.c b/fs/xfs/xfs_pwork.c
> index 8d0d5f130252..c2f02b710b8c 100644
> --- a/fs/xfs/xfs_pwork.c
> +++ b/fs/xfs/xfs_pwork.c
> @@ -13,6 +13,7 @@
> #include "xfs_trace.h"
> #include "xfs_sysctl.h"
> #include "xfs_pwork.h"
> +#include <linux/nmi.h>
>
> /*
> * Parallel Work Queue
> @@ -46,6 +47,8 @@ xfs_pwork_work(
> error = pctl->work_fn(pctl->mp, pwork);
> if (error && !pctl->error)
> pctl->error = error;
> + atomic_dec(&pctl->nr_work);
> + wake_up(&pctl->poll_wait);
We could use atomic_dec_and_test() here to avoid some unnecessary
wakeups. With that fixed up:
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> }
>
> /*
> @@ -76,6 +79,8 @@ xfs_pwork_init(
> pctl->work_fn = work_fn;
> pctl->error = 0;
> pctl->mp = mp;
> + atomic_set(&pctl->nr_work, 0);
> + init_waitqueue_head(&pctl->poll_wait);
>
> return 0;
> }
> @@ -88,6 +93,7 @@ xfs_pwork_queue(
> {
> INIT_WORK(&pwork->work, xfs_pwork_work);
> pwork->pctl = pctl;
> + atomic_inc(&pctl->nr_work);
> queue_work(pctl->wq, &pwork->work);
> }
>
> @@ -101,6 +107,19 @@ xfs_pwork_destroy(
> return pctl->error;
> }
>
> +/*
> + * Wait for the work to finish by polling completion status and touch the soft
> + * lockup watchdog. This is for callers such as mount which hold locks.
> + */
> +void
> +xfs_pwork_poll(
> + struct xfs_pwork_ctl *pctl)
> +{
> + while (wait_event_timeout(pctl->poll_wait,
> + atomic_read(&pctl->nr_work) == 0, HZ) == 0)
> + touch_softlockup_watchdog();
> +}
> +
> /*
> * Return the amount of parallelism that the data device can handle, or 0 for
> * no limit.
> diff --git a/fs/xfs/xfs_pwork.h b/fs/xfs/xfs_pwork.h
> index 4cf1a6f48237..ff93873df8d3 100644
> --- a/fs/xfs/xfs_pwork.h
> +++ b/fs/xfs/xfs_pwork.h
> @@ -18,6 +18,8 @@ struct xfs_pwork_ctl {
> struct workqueue_struct *wq;
> struct xfs_mount *mp;
> xfs_pwork_work_fn work_fn;
> + struct wait_queue_head poll_wait;
> + atomic_t nr_work;
> int error;
> };
>
> @@ -53,6 +55,7 @@ int xfs_pwork_init(struct xfs_mount *mp, struct xfs_pwork_ctl *pctl,
> unsigned int nr_threads);
> void xfs_pwork_queue(struct xfs_pwork_ctl *pctl, struct xfs_pwork *pwork);
> int xfs_pwork_destroy(struct xfs_pwork_ctl *pctl);
> +void xfs_pwork_poll(struct xfs_pwork_ctl *pctl);
> unsigned int xfs_pwork_guess_datadev_parallelism(struct xfs_mount *mp);
>
> #endif /* __XFS_PWORK_H__ */
> diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
> index 8004c931c86e..8bb902125403 100644
> --- a/fs/xfs/xfs_qm.c
> +++ b/fs/xfs/xfs_qm.c
> @@ -1304,7 +1304,7 @@ xfs_qm_quotacheck(
> flags |= XFS_PQUOTA_CHKD;
> }
>
> - error = xfs_iwalk_threaded(mp, 0, xfs_qm_dqusage_adjust, 0, NULL);
> + error = xfs_iwalk_threaded(mp, 0, xfs_qm_dqusage_adjust, 0, true, NULL);
> if (error)
> goto error_return;
>
>
