[PATCH 09/11] xfs: multithreaded iwalk implementation

Darrick J. Wong
2019-05-29T22:27:21Z

Create a parallel iwalk implementation and switch quotacheck to use it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/Makefile | 1
fs/xfs/xfs_globals.c | 3 +
fs/xfs/xfs_iwalk.c | 76 +++++++++++++++++++++++++++++++-
fs/xfs/xfs_iwalk.h | 2 +
fs/xfs/xfs_pwork.c | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/xfs_pwork.h | 50 +++++++++++++++++++++
fs/xfs/xfs_qm.c | 2 -
fs/xfs/xfs_sysctl.h | 6 +++
fs/xfs/xfs_sysfs.c | 40 +++++++++++++++++
fs/xfs/xfs_trace.h | 18 ++++++++
10 files changed, 313 insertions(+), 3 deletions(-)
create mode 100644 fs/xfs/xfs_pwork.c
create mode 100644 fs/xfs/xfs_pwork.h

diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index 74d30ef0dbce..48940a27d4aa 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -84,6 +84,7 @@ xfs-y += xfs_aops.o \
xfs_message.o \
xfs_mount.o \
xfs_mru_cache.o \
+ xfs_pwork.o \
xfs_reflink.o \
xfs_stats.o \
xfs_super.o \
diff --git a/fs/xfs/xfs_globals.c b/fs/xfs/xfs_globals.c
index d0d377384120..4f93f2c4dc38 100644
--- a/fs/xfs/xfs_globals.c
+++ b/fs/xfs/xfs_globals.c
@@ -31,6 +31,9 @@ xfs_param_t xfs_params = {
.fstrm_timer = { 1, 30*100, 3600*100},
.eofb_timer = { 1, 300, 3600*24},
.cowb_timer = { 1, 1800, 3600*24},
+#ifdef DEBUG
+ .pwork_threads = { 0, 0, NR_CPUS },
+#endif
};

struct xfs_globals xfs_globals = {
diff --git a/fs/xfs/xfs_iwalk.c b/fs/xfs/xfs_iwalk.c
index 3c523afdcfa0..453790bae194 100644
--- a/fs/xfs/xfs_iwalk.c
+++ b/fs/xfs/xfs_iwalk.c
@@ -21,6 +21,7 @@
#include "xfs_health.h"
#include "xfs_trans.h"
#include "xfs_iwalk.h"
+#include "xfs_pwork.h"

/*
* Walking All the Inodes in the Filesystem
@@ -38,6 +39,9 @@
*/

struct xfs_iwalk_ag {
+ /* parallel work control data; will be null if single threaded */
+ struct xfs_pwork pwork;
+
struct xfs_mount *mp;
struct xfs_trans *tp;

@@ -190,6 +194,9 @@ xfs_iwalk_ag_recs(
trace_xfs_iwalk_ag_rec(mp, agno, irec->ir_startino,
irec->ir_free);
for (j = 0; j < XFS_INODES_PER_CHUNK; j++) {
+ if (xfs_pwork_want_abort(&iwag->pwork))
+ return 0;
+
/* Skip if this inode is free */
if (XFS_INOBT_MASK(j) & irec->ir_free)
continue;
@@ -374,7 +381,7 @@ xfs_iwalk_ag(
if (error)
goto out_cur;

- while (has_more) {
+ while (has_more && !xfs_pwork_want_abort(&iwag->pwork)) {
struct xfs_inobt_rec_incore *irec;

/* Fetch the inobt record. */
@@ -410,7 +417,7 @@ xfs_iwalk_ag(
}

/* Walk any records left behind in the cache. */
- if (iwag->nr_recs) {
+ if (iwag->nr_recs && !xfs_pwork_want_abort(&iwag->pwork)) {
xfs_iwalk_del_inobt(tp, &cur, &agi_bp, error);
return xfs_iwalk_ag_recs(iwag);
}
@@ -469,6 +476,7 @@ xfs_iwalk(
.iwalk_fn = iwalk_fn,
.data = data,
.startino = startino,
+ .pwork = XFS_PWORK_SINGLE_THREADED,
};
xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino);
int error;
@@ -490,3 +498,67 @@ xfs_iwalk(
xfs_iwalk_freebuf(&iwag);
return error;
}
+
+/* Run per-thread iwalk work. */
+static int
+xfs_iwalk_ag_work(
+ struct xfs_mount *mp,
+ struct xfs_pwork *pwork)
+{
+ struct xfs_iwalk_ag *iwag;
+ int error;
+
+ iwag = container_of(pwork, struct xfs_iwalk_ag, pwork);
+ error = xfs_iwalk_allocbuf(iwag);
+ if (error)
+ goto out;
+
+ error = xfs_iwalk_ag(iwag);
+ xfs_iwalk_freebuf(iwag);
+out:
+ kmem_free(iwag);
+ return error;
+}
+
+/*
+ * Walk all the inodes in the filesystem using multiple threads to process each
+ * AG.
+ */
+int
+xfs_iwalk_threaded(
+ struct xfs_mount *mp,
+ xfs_ino_t startino,
+ xfs_iwalk_fn iwalk_fn,
+ unsigned int max_prefetch,
+ void *data)
+{
+ struct xfs_pwork_ctl pctl;
+ xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, startino);
+ unsigned int nr_threads;
+ int error;
+
+ ASSERT(agno < mp->m_sb.sb_agcount);
+
+ nr_threads = xfs_pwork_guess_datadev_parallelism(mp);
+ error = xfs_pwork_init(mp, &pctl, xfs_iwalk_ag_work, "xfs_iwalk",
+ nr_threads);
+ if (error)
+ return error;
+
+ for (; agno < mp->m_sb.sb_agcount; agno++) {
+ struct xfs_iwalk_ag *iwag;
+
+ iwag = kmem_alloc(sizeof(struct xfs_iwalk_ag), KM_SLEEP);
+ iwag->mp = mp;
+ iwag->tp = NULL;
+ iwag->iwalk_fn = iwalk_fn;
+ iwag->data = data;
+ iwag->startino = startino;
+ iwag->recs = NULL;
+ xfs_iwalk_set_prefetch(iwag, max_prefetch);
+ xfs_pwork_queue(&pctl, &iwag->pwork);
+ startino = XFS_AGINO_TO_INO(mp, agno + 1, 0);
+ }
+
+ return xfs_pwork_destroy(&pctl);
+}
diff --git a/fs/xfs/xfs_iwalk.h b/fs/xfs/xfs_iwalk.h
index 45b1baabcd2d..40233a05a766 100644
--- a/fs/xfs/xfs_iwalk.h
+++ b/fs/xfs/xfs_iwalk.h
@@ -14,5 +14,7 @@ typedef int (*xfs_iwalk_fn)(struct xfs_mount *mp, struct xfs_trans *tp,

int xfs_iwalk(struct xfs_mount *mp, struct xfs_trans *tp, xfs_ino_t startino,
xfs_iwalk_fn iwalk_fn, unsigned int max_prefetch, void *data);
+int xfs_iwalk_threaded(struct xfs_mount *mp, xfs_ino_t startino,
+ xfs_iwalk_fn iwalk_fn, unsigned int max_prefetch, void *data);

#endif /* __XFS_IWALK_H__ */
diff --git a/fs/xfs/xfs_pwork.c b/fs/xfs/xfs_pwork.c
new file mode 100644
index 000000000000..c1419558b089
--- /dev/null
+++ b/fs/xfs/xfs_pwork.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * 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
+ * cause all threads to abort.
+ */
+
+/* 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;
+ int iomin;
+ int ioopt;
+
+ if (blk_queue_nonrot(btp->bt_bdev->bd_queue))
+ return num_online_cpus();
+ if (mp->m_sb.sb_width && mp->m_sb.sb_unit)
+ return mp->m_sb.sb_width / mp->m_sb.sb_unit;
+ iomin = bdev_io_min(btp->bt_bdev);
+ ioopt = bdev_io_opt(btp->bt_bdev);
+ if (iomin && ioopt)
+ return ioopt / iomin;
+
+ return 1;
+}
diff --git a/fs/xfs/xfs_pwork.h b/fs/xfs/xfs_pwork.h
new file mode 100644
index 000000000000..e0c1354a2d8c
--- /dev/null
+++ b/fs/xfs/xfs_pwork.h
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#ifndef __XFS_PWORK_H__
+#define __XFS_PWORK_H__
+
+struct xfs_pwork;
+struct xfs_mount;
+
+typedef int (*xfs_pwork_work_fn)(struct xfs_mount *mp, struct xfs_pwork *pwork);
+
+/*
+ * Parallel work coordination structure.
+ */
+struct xfs_pwork_ctl {
+ struct workqueue_struct *wq;
+ struct xfs_mount *mp;
+ xfs_pwork_work_fn work_fn;
+ int error;
+};
+
+/*
+ * Embed this parallel work control item inside your own work structure,
+ * then queue work with it.
+ */
+struct xfs_pwork {
+ struct work_struct work;
+ struct xfs_pwork_ctl *pctl;
+};
+
+#define XFS_PWORK_SINGLE_THREADED { .pctl = NULL }
+
+/* Have we been told to abort? */
+static inline bool
+xfs_pwork_want_abort(
+ struct xfs_pwork *pwork)
+{
+ return pwork->pctl && pwork->pctl->error;
+}
+
+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);
+void xfs_pwork_queue(struct xfs_pwork_ctl *pctl, struct xfs_pwork *pwork);
+int xfs_pwork_destroy(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 a5b2260406a8..e4f3785f7a64 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -1305,7 +1305,7 @@ xfs_qm_quotacheck(
flags |= XFS_PQUOTA_CHKD;
}

- error = xfs_iwalk(mp, NULL, 0, xfs_qm_dqusage_adjust, 0, NULL);
+ error = xfs_iwalk_threaded(mp, 0, xfs_qm_dqusage_adjust, 0, NULL);
if (error)
goto error_return;

diff --git a/fs/xfs/xfs_sysctl.h b/fs/xfs/xfs_sysctl.h
index ad7f9be13087..b555e045e2f4 100644
--- a/fs/xfs/xfs_sysctl.h
+++ b/fs/xfs/xfs_sysctl.h
@@ -37,6 +37,9 @@ typedef struct xfs_param {
xfs_sysctl_val_t fstrm_timer; /* Filestream dir-AG assoc'n timeout. */
xfs_sysctl_val_t eofb_timer; /* Interval between eofb scan wakeups */
xfs_sysctl_val_t cowb_timer; /* Interval between cowb scan wakeups */
+#ifdef DEBUG
+ xfs_sysctl_val_t pwork_threads; /* Parallel workqueue thread count */
+#endif
} xfs_param_t;

/*
@@ -82,6 +85,9 @@ enum {
extern xfs_param_t xfs_params;

struct xfs_globals {
+#ifdef DEBUG
+ int pwork_threads; /* parallel workqueue threads */
+#endif
int log_recovery_delay; /* log recovery delay (secs) */
int mount_delay; /* mount setup delay (secs) */
bool bug_on_assert; /* BUG() the kernel on assert failure */
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index cabda13f3c64..910e6b9cb1a7 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -206,11 +206,51 @@ always_cow_show(
}
XFS_SYSFS_ATTR_RW(always_cow);

+#ifdef DEBUG
+/*
+ * Override how many threads the parallel work queue is allowed to create.
+ * This has to be a debug-only global (instead of an errortag) because one of
+ * the main users of parallel workqueues is mount time quotacheck.
+ */
+STATIC ssize_t
+pwork_threads_store(
+ struct kobject *kobject,
+ const char *buf,
+ size_t count)
+{
+ int ret;
+ int val;
+
+ ret = kstrtoint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ if (val < 0 || val > NR_CPUS)
+ return -EINVAL;
+
+ xfs_globals.pwork_threads = val;
+
+ return count;
+}
+
+STATIC ssize_t
+pwork_threads_show(
+ struct kobject *kobject,
+ char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.pwork_threads);
+}
+XFS_SYSFS_ATTR_RW(pwork_threads);
+#endif /* DEBUG */
+
static struct attribute *xfs_dbg_attrs[] = {
ATTR_LIST(bug_on_assert),
ATTR_LIST(log_recovery_delay),
ATTR_LIST(mount_delay),
ATTR_LIST(always_cow),
+#ifdef DEBUG
+ ATTR_LIST(pwork_threads),
+#endif
NULL,
};

diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index a2881659f776..5c0eea7bfcb0 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -3556,6 +3556,24 @@ TRACE_EVENT(xfs_iwalk_ag_rec,
__entry->startino, __entry->freemask)
)

+TRACE_EVENT(xfs_pwork_init,
+ TP_PROTO(struct xfs_mount *mp, unsigned int nr_threads, pid_t pid),
+ TP_ARGS(mp, nr_threads, pid),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(unsigned int, nr_threads)
+ __field(pid_t, pid)
+ ),
+ TP_fast_assign(
+ __entry->dev = mp->m_super->s_dev;
+ __entry->nr_threads = nr_threads;
+ __entry->pid = pid;
+ ),
+ TP_printk("dev %d:%d nr_threads %u pid %u",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->nr_threads, __entry->pid)
+)
+
#endif /* _TRACE_XFS_H */

#undef TRACE_INCLUDE_PATH