// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2019 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <darrick.wong@oracle.com>
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_trace.h"
#include "xfs_sysctl.h"
#include "xfs_pwork.h"
#include <linux/nmi.h>
/*
* Parallel Work Queue
* ===================
*
* Abstract away the details of running a large and "obviously" parallelizable
* task across multiple CPUs. Callers initialize the pwork control object with
* a desired level of parallelization and a work function. Next, they embed
* struct xfs_pwork in whatever structure they use to pass work context to a
* worker thread and queue that pwork. The work function will be passed the
* pwork item when it is run (from process context) and any returned error will
* be recorded in xfs_pwork_ctl.error. Work functions should check for errors
* and abort if necessary; the non-zeroness of xfs_pwork_ctl.error does not
* stop workqueue item processing.
*
* This is the rough equivalent of the xfsprogs workqueue code, though we can't
* reuse that name here.
*/
/* Invoke our caller's function. */
static void
xfs_pwork_work(
struct work_struct *work)
{
struct xfs_pwork *pwork;
struct xfs_pwork_ctl *pctl;
int error;
pwork = container_of(work, struct xfs_pwork, work);
pctl = pwork->pctl;
error = pctl->work_fn(pctl->mp, pwork);
if (error && !pctl->error)
pctl->error = error;
if (atomic_dec_and_test(&pctl->nr_work))
wake_up(&pctl->poll_wait);
}
/*
* Set up control data for parallel work. @work_fn is the function that will
* be called. @tag will be written into the kernel threads. @nr_threads is
* the level of parallelism desired, or 0 for no limit.
*/
int
xfs_pwork_init(
struct xfs_mount *mp,
struct xfs_pwork_ctl *pctl,
xfs_pwork_work_fn work_fn,
const char *tag,
unsigned int nr_threads)
{
#ifdef DEBUG
if (xfs_globals.pwork_threads >= 0)
nr_threads = xfs_globals.pwork_threads;
#endif
trace_xfs_pwork_init(mp, nr_threads, current->pid);
pctl->wq = alloc_workqueue("%s-%d", WQ_FREEZABLE, nr_threads, tag,
current->pid);
if (!pctl->wq)
return -ENOMEM;
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;
}
/* Queue some parallel work. */
void
xfs_pwork_queue(
struct xfs_pwork_ctl *pctl,
struct xfs_pwork *pwork)
{
INIT_WORK(&pwork->work, xfs_pwork_work);
pwork->pctl = pctl;
atomic_inc(&pctl->nr_work);
queue_work(pctl->wq, &pwork->work);
}
/* Wait for the work to finish and tear down the control structure. */
int
xfs_pwork_destroy(
struct xfs_pwork_ctl *pctl)
{
destroy_workqueue(pctl->wq);
pctl->wq = NULL;
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.
*/
unsigned int
xfs_pwork_guess_datadev_parallelism(
struct xfs_mount *mp)
{
struct xfs_buftarg *btp = mp->m_ddev_targp;
/*
* For now we'll go with the most conservative setting possible,
* which is two threads for an SSD and 1 thread everywhere else.
*/
return blk_queue_nonrot(btp->bt_bdev->bd_queue) ? 2 : 1;
}
