scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 98 insertions, 0 deletions

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
new file mode 100644
index 000000000..49f56a598
--- /dev/null
+++ b/fs/drop_caches.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Implement the manual drop-all-pagecache function
+ */
+
+#include <linux/pagemap.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/writeback.h>
+#include <linux/sysctl.h>
+#include <linux/gfp.h>
+#include <linux/swap.h>
+#include "internal.h"
+
+/* A global variable is a bit ugly, but it keeps the code simple */
+static int sysctl_drop_caches;
+
+static void drop_pagecache_sb(struct super_block *sb, void *unused)
+{
+	struct inode *inode, *toput_inode = NULL;
+
+	spin_lock(&sb->s_inode_list_lock);
+	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+		spin_lock(&inode->i_lock);
+		/*
+		 * We must skip inodes in unusual state. We may also skip
+		 * inodes without pages but we deliberately won't in case
+		 * we need to reschedule to avoid softlockups.
+		 */
+		if ((inode_state_read(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) ||
+		    (mapping_empty(inode->i_mapping) && !need_resched())) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}
+		__iget(inode);
+		spin_unlock(&inode->i_lock);
+		spin_unlock(&sb->s_inode_list_lock);
+
+		invalidate_mapping_pages(inode->i_mapping, 0, -1);
+		iput(toput_inode);
+		toput_inode = inode;
+
+		cond_resched();
+		spin_lock(&sb->s_inode_list_lock);
+	}
+	spin_unlock(&sb->s_inode_list_lock);
+	iput(toput_inode);
+}
+
+static int drop_caches_sysctl_handler(const struct ctl_table *table, int write,
+		void *buffer, size_t *length, loff_t *ppos)
+{
+	int ret;
+
+	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+	if (ret)
+		return ret;
+	if (write) {
+		static int stfu;
+
+		if (sysctl_drop_caches & 1) {
+			lru_add_drain_all();
+			iterate_supers(drop_pagecache_sb, NULL);
+			count_vm_event(DROP_PAGECACHE);
+		}
+		if (sysctl_drop_caches & 2) {
+			drop_slab();
+			count_vm_event(DROP_SLAB);
+		}
+		if (!stfu) {
+			pr_info("%s (%d): drop_caches: %d\n",
+				current->comm, task_pid_nr(current),
+				sysctl_drop_caches);
+		}
+		stfu |= sysctl_drop_caches & 4;
+	}
+	return 0;
+}
+
+static const struct ctl_table drop_caches_table[] = {
+	{
+		.procname	= "drop_caches",
+		.data		= &sysctl_drop_caches,
+		.maxlen		= sizeof(int),
+		.mode		= 0200,
+		.proc_handler	= drop_caches_sysctl_handler,
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_FOUR,
+	},
+};
+
+static int __init init_vm_drop_caches_sysctls(void)
+{
+	register_sysctl_init("vm", drop_caches_table);
+	return 0;
+}
+fs_initcall(init_vm_drop_caches_sysctls);