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diff --git a/fs/xfs/xfs_pwork.c b/fs/xfs/xfs_pwork.c
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+// 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"
+
+/*
+ * 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;
+}
+
+/*
+ * 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;
+
+ 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;
+ 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;
+}
+
+/*
+ * 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;
+}