fs/xfs/xfs_pwork.c

Source file repositories/reference/linux-study-clean/fs/xfs/xfs_pwork.c

File Facts

System
Linux kernel
Corpus path
fs/xfs/xfs_pwork.c
Extension
.c
Size
3246 bytes
Lines
122
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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_platform.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 = 0;

#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_UNBOUND | WQ_SYSFS | 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(

Annotation

Implementation Notes