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, 213 insertions, 0 deletions

diff --git a/fs/ceph/io.c b/fs/ceph/io.c
new file mode 100644
index 000000000..2d10f49c9
--- /dev/null
+++ b/fs/ceph/io.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2016 Trond Myklebust
+ * Copyright (c) 2019 Jeff Layton
+ *
+ * I/O and data path helper functionality.
+ *
+ * Heavily borrowed from equivalent code in fs/nfs/io.c
+ */
+
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/rwsem.h>
+#include <linux/fs.h>
+
+#include "super.h"
+#include "io.h"
+
+/* Call with exclusively locked inode->i_rwsem */
+static void ceph_block_o_direct(struct ceph_inode_info *ci, struct inode *inode)
+{
+	bool is_odirect;
+
+	lockdep_assert_held_write(&inode->i_rwsem);
+
+	spin_lock(&ci->i_ceph_lock);
+	/* ensure that bit state is consistent */
+	smp_mb__before_atomic();
+	is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT;
+	if (is_odirect) {
+		clear_bit(CEPH_I_ODIRECT_BIT, &ci->i_ceph_flags);
+		/* ensure modified bit is visible */
+		smp_mb__after_atomic();
+	}
+	spin_unlock(&ci->i_ceph_lock);
+
+	if (is_odirect)
+		inode_dio_wait(inode);
+}
+
+/**
+ * ceph_start_io_read - declare the file is being used for buffered reads
+ * @inode: file inode
+ *
+ * Declare that a buffered read operation is about to start, and ensure
+ * that we block all direct I/O.
+ * On exit, the function ensures that the CEPH_I_ODIRECT flag is unset,
+ * and holds a shared lock on inode->i_rwsem to ensure that the flag
+ * cannot be changed.
+ * In practice, this means that buffered read operations are allowed to
+ * execute in parallel, thanks to the shared lock, whereas direct I/O
+ * operations need to wait to grab an exclusive lock in order to set
+ * CEPH_I_ODIRECT.
+ * Note that buffered writes and truncates both take a write lock on
+ * inode->i_rwsem, meaning that those are serialised w.r.t. the reads.
+ */
+int ceph_start_io_read(struct inode *inode)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	bool is_odirect;
+	int err;
+
+	/* Be an optimist! */
+	err = down_read_killable(&inode->i_rwsem);
+	if (err)
+		return err;
+
+	spin_lock(&ci->i_ceph_lock);
+	/* ensure that bit state is consistent */
+	smp_mb__before_atomic();
+	is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT;
+	spin_unlock(&ci->i_ceph_lock);
+	if (!is_odirect)
+		return 0;
+	up_read(&inode->i_rwsem);
+
+	/* Slow path.... */
+	err = down_write_killable(&inode->i_rwsem);
+	if (err)
+		return err;
+
+	ceph_block_o_direct(ci, inode);
+	downgrade_write(&inode->i_rwsem);
+
+	return 0;
+}
+
+/**
+ * ceph_end_io_read - declare that the buffered read operation is done
+ * @inode: file inode
+ *
+ * Declare that a buffered read operation is done, and release the shared
+ * lock on inode->i_rwsem.
+ */
+void
+ceph_end_io_read(struct inode *inode)
+{
+	up_read(&inode->i_rwsem);
+}
+
+/**
+ * ceph_start_io_write - declare the file is being used for buffered writes
+ * @inode: file inode
+ *
+ * Declare that a buffered write operation is about to start, and ensure
+ * that we block all direct I/O.
+ */
+int ceph_start_io_write(struct inode *inode)
+{
+	int err = down_write_killable(&inode->i_rwsem);
+	if (!err)
+		ceph_block_o_direct(ceph_inode(inode), inode);
+	return err;
+}
+
+/**
+ * ceph_end_io_write - declare that the buffered write operation is done
+ * @inode: file inode
+ *
+ * Declare that a buffered write operation is done, and release the
+ * lock on inode->i_rwsem.
+ */
+void
+ceph_end_io_write(struct inode *inode)
+{
+	up_write(&inode->i_rwsem);
+}
+
+/* Call with exclusively locked inode->i_rwsem */
+static void ceph_block_buffered(struct ceph_inode_info *ci, struct inode *inode)
+{
+	bool is_odirect;
+
+	lockdep_assert_held_write(&inode->i_rwsem);
+
+	spin_lock(&ci->i_ceph_lock);
+	/* ensure that bit state is consistent */
+	smp_mb__before_atomic();
+	is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT;
+	if (!is_odirect) {
+		set_bit(CEPH_I_ODIRECT_BIT, &ci->i_ceph_flags);
+		/* ensure modified bit is visible */
+		smp_mb__after_atomic();
+	}
+	spin_unlock(&ci->i_ceph_lock);
+
+	if (!is_odirect) {
+		/* FIXME: unmap_mapping_range? */
+		filemap_write_and_wait(inode->i_mapping);
+	}
+}
+
+/**
+ * ceph_start_io_direct - declare the file is being used for direct i/o
+ * @inode: file inode
+ *
+ * Declare that a direct I/O operation is about to start, and ensure
+ * that we block all buffered I/O.
+ * On exit, the function ensures that the CEPH_I_ODIRECT flag is set,
+ * and holds a shared lock on inode->i_rwsem to ensure that the flag
+ * cannot be changed.
+ * In practice, this means that direct I/O operations are allowed to
+ * execute in parallel, thanks to the shared lock, whereas buffered I/O
+ * operations need to wait to grab an exclusive lock in order to clear
+ * CEPH_I_ODIRECT.
+ * Note that buffered writes and truncates both take a write lock on
+ * inode->i_rwsem, meaning that those are serialised w.r.t. O_DIRECT.
+ */
+int ceph_start_io_direct(struct inode *inode)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	bool is_odirect;
+	int err;
+
+	/* Be an optimist! */
+	err = down_read_killable(&inode->i_rwsem);
+	if (err)
+		return err;
+
+	spin_lock(&ci->i_ceph_lock);
+	/* ensure that bit state is consistent */
+	smp_mb__before_atomic();
+	is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT;
+	spin_unlock(&ci->i_ceph_lock);
+	if (is_odirect)
+		return 0;
+	up_read(&inode->i_rwsem);
+
+	/* Slow path.... */
+	err = down_write_killable(&inode->i_rwsem);
+	if (err)
+		return err;
+
+	ceph_block_buffered(ci, inode);
+	downgrade_write(&inode->i_rwsem);
+
+	return 0;
+}
+
+/**
+ * ceph_end_io_direct - declare that the direct i/o operation is done
+ * @inode: file inode
+ *
+ * Declare that a direct I/O operation is done, and release the shared
+ * lock on inode->i_rwsem.
+ */
+void
+ceph_end_io_direct(struct inode *inode)
+{
+	up_read(&inode->i_rwsem);
+}