staging: ramster: place ramster codebase on top of new zcache2 codebase

[V2: rebased to apply to 20120905 staging-next, no other changes]

This slightly modified ramster codebase is now built entirely on zcache2
and all ramster-specific code is fully contained in a subdirectory.

Ramster extends zcache2 to allow pages compressed via zcache2 to be
"load-balanced" across machines in a cluster.  Control and data communication
is done via kernel sockets, and cluster configuration and management is
heavily leveraged from the ocfs2 cluster filesystem.

There are no new features since the codebase introduced into staging at 3.4.
Some cleanup was performed though:
 1) Interfaces directly with new zbud
 2) Debugfs now used instead of sysfs where possible.  Sysfs still
    used where necessary for userland cluster configuration.

Ramster is very much a work-in-progress but also does really work!

RAMSTER HIGH LEVEL OVERVIEW (from original V5 posting in Feb 2012)

RAMster implements peer-to-peer transcendent memory, allowing a "cluster" of
kernels to dynamically pool their RAM so that a RAM-hungry workload on one
machine can temporarily and transparently utilize RAM on another machine which
is presumably idle or running a non-RAM-hungry workload.  Other than the
already-merged cleancache patchset and frontswap patchset, no core kernel
changes are currently required.

(Note that, unlike previous public descriptions of RAMster, this implementation
does NOT require synchronous "gets" or core networking changes. As of V5,
it also co-exists with ocfs2.)

RAMster combines a clustering and messaging foundation based on the ocfs2
cluster layer with the in-kernel compression implementation of zcache2, and
adds code to glue them together.  When a page is "put" to RAMster, it is
compressed and stored locally.  Periodically, a thread will "remotify" these
pages by sending them via messages to a remote machine.  When the page is
later needed as indicated by a page fault, a "get" is issued.  If the data
is local, it is uncompressed and the fault is resolved.  If the data is
remote, a message is sent to fetch the data and the faulting thread sleeps;
when the data arrives, the thread awakens, the data is decompressed and
the fault is resolved.

As of V5, clusters up to eight nodes are supported; each node can remotify
pages to one specified node, so clusters can be configured as clients to
a "memory server".  Some simple policy is in place that will need to be
refined over time.  Larger clusters and fault-resistant protocols can also
be added over time.

A HOW-TO is available at:
http://oss.oracle.com/projects/tmem/dist/files/RAMster/HOWTO-120817

Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 414 insertions, 0 deletions

diff --git a/drivers/staging/ramster/ramster/r2net.c b/drivers/staging/ramster/ramster/r2net.c
new file mode 100644
index 000000000000..34818dc65612
--- /dev/null
+++ b/drivers/staging/ramster/ramster/r2net.c
@@ -0,0 +1,414 @@
+/*
+ * r2net.c
+ *
+ * Copyright (c) 2011-2012, Dan Magenheimer, Oracle Corp.
+ *
+ * Ramster_r2net provides an interface between zcache and r2net.
+ *
+ * FIXME: support more than two nodes
+ */
+
+#include <linux/list.h>
+#include "tcp.h"
+#include "nodemanager.h"
+#include "../tmem.h"
+#include "../zcache.h"
+#include "ramster.h"
+
+#define RAMSTER_TESTING
+
+#define RMSTR_KEY	0x77347734
+
+enum {
+	RMSTR_TMEM_PUT_EPH = 100,
+	RMSTR_TMEM_PUT_PERS,
+	RMSTR_TMEM_ASYNC_GET_REQUEST,
+	RMSTR_TMEM_ASYNC_GET_AND_FREE_REQUEST,
+	RMSTR_TMEM_ASYNC_GET_REPLY,
+	RMSTR_TMEM_FLUSH,
+	RMSTR_TMEM_FLOBJ,
+	RMSTR_TMEM_DESTROY_POOL,
+};
+
+#define RMSTR_R2NET_MAX_LEN \
+		(R2NET_MAX_PAYLOAD_BYTES - sizeof(struct tmem_xhandle))
+
+#include "tcp_internal.h"
+
+static struct r2nm_node *r2net_target_node;
+static int r2net_target_nodenum;
+
+int r2net_remote_target_node_set(int node_num)
+{
+	int ret = -1;
+
+	r2net_target_node = r2nm_get_node_by_num(node_num);
+	if (r2net_target_node != NULL) {
+		r2net_target_nodenum = node_num;
+		r2nm_node_put(r2net_target_node);
+		ret = 0;
+	}
+	return ret;
+}
+
+/* FIXME following buffer should be per-cpu, protected by preempt_disable */
+static char ramster_async_get_buf[R2NET_MAX_PAYLOAD_BYTES];
+
+static int ramster_remote_async_get_request_handler(struct r2net_msg *msg,
+				u32 len, void *data, void **ret_data)
+{
+	char *pdata;
+	struct tmem_xhandle xh;
+	int found;
+	size_t size = RMSTR_R2NET_MAX_LEN;
+	u16 msgtype = be16_to_cpu(msg->msg_type);
+	bool get_and_free = (msgtype == RMSTR_TMEM_ASYNC_GET_AND_FREE_REQUEST);
+	unsigned long flags;
+
+	xh = *(struct tmem_xhandle *)msg->buf;
+	if (xh.xh_data_size > RMSTR_R2NET_MAX_LEN)
+		BUG();
+	pdata = ramster_async_get_buf;
+	*(struct tmem_xhandle *)pdata = xh;
+	pdata += sizeof(struct tmem_xhandle);
+	local_irq_save(flags);
+	found = zcache_get_page(xh.client_id, xh.pool_id, &xh.oid, xh.index,
+				pdata, &size, true, get_and_free ? 1 : -1);
+	local_irq_restore(flags);
+	if (found < 0) {
+		/* a zero size indicates the get failed */
+		size = 0;
+	}
+	if (size > RMSTR_R2NET_MAX_LEN)
+		BUG();
+	*ret_data = pdata - sizeof(struct tmem_xhandle);
+	/* now make caller (r2net_process_message) handle specially */
+	r2net_force_data_magic(msg, RMSTR_TMEM_ASYNC_GET_REPLY, RMSTR_KEY);
+	return size + sizeof(struct tmem_xhandle);
+}
+
+static int ramster_remote_async_get_reply_handler(struct r2net_msg *msg,
+				u32 len, void *data, void **ret_data)
+{
+	char *in = (char *)msg->buf;
+	int datalen = len - sizeof(struct r2net_msg);
+	int ret = -1;
+	struct tmem_xhandle *xh = (struct tmem_xhandle *)in;
+
+	in += sizeof(struct tmem_xhandle);
+	datalen -= sizeof(struct tmem_xhandle);
+	BUG_ON(datalen < 0 || datalen > PAGE_SIZE);
+	ret = ramster_localify(xh->pool_id, &xh->oid, xh->index,
+				in, datalen, xh->extra);
+#ifdef RAMSTER_TESTING
+	if (ret == -EEXIST)
+		pr_err("TESTING ArrgREP, aborted overwrite on racy put\n");
+#endif
+	return ret;
+}
+
+int ramster_remote_put_handler(struct r2net_msg *msg,
+				u32 len, void *data, void **ret_data)
+{
+	struct tmem_xhandle *xh;
+	char *p = (char *)msg->buf;
+	int datalen = len - sizeof(struct r2net_msg) -
+				sizeof(struct tmem_xhandle);
+	u16 msgtype = be16_to_cpu(msg->msg_type);
+	bool ephemeral = (msgtype == RMSTR_TMEM_PUT_EPH);
+	unsigned long flags;
+	int ret;
+
+	xh = (struct tmem_xhandle *)p;
+	p += sizeof(struct tmem_xhandle);
+	zcache_autocreate_pool(xh->client_id, xh->pool_id, ephemeral);
+	local_irq_save(flags);
+	ret = zcache_put_page(xh->client_id, xh->pool_id, &xh->oid, xh->index,
+				p, datalen, true, ephemeral);
+	local_irq_restore(flags);
+	return ret;
+}
+
+int ramster_remote_flush_handler(struct r2net_msg *msg,
+				u32 len, void *data, void **ret_data)
+{
+	struct tmem_xhandle *xh;
+	char *p = (char *)msg->buf;
+
+	xh = (struct tmem_xhandle *)p;
+	p += sizeof(struct tmem_xhandle);
+	(void)zcache_flush_page(xh->client_id, xh->pool_id,
+					&xh->oid, xh->index);
+	return 0;
+}
+
+int ramster_remote_flobj_handler(struct r2net_msg *msg,
+				u32 len, void *data, void **ret_data)
+{
+	struct tmem_xhandle *xh;
+	char *p = (char *)msg->buf;
+
+	xh = (struct tmem_xhandle *)p;
+	p += sizeof(struct tmem_xhandle);
+	(void)zcache_flush_object(xh->client_id, xh->pool_id, &xh->oid);
+	return 0;
+}
+
+int r2net_remote_async_get(struct tmem_xhandle *xh, bool free, int remotenode,
+				size_t expect_size, uint8_t expect_cksum,
+				void *extra)
+{
+	int nodenum, ret = -1, status;
+	struct r2nm_node *node = NULL;
+	struct kvec vec[1];
+	size_t veclen = 1;
+	u32 msg_type;
+	struct r2net_node *nn;
+
+	node = r2nm_get_node_by_num(remotenode);
+	if (node == NULL)
+		goto out;
+	xh->client_id = r2nm_this_node(); /* which node is getting */
+	xh->xh_data_cksum = expect_cksum;
+	xh->xh_data_size = expect_size;
+	xh->extra = extra;
+	vec[0].iov_len = sizeof(*xh);
+	vec[0].iov_base = xh;
+
+	node = r2net_target_node;
+	if (!node)
+		goto out;
+
+	nodenum = r2net_target_nodenum;
+
+	r2nm_node_get(node);
+	nn = r2net_nn_from_num(nodenum);
+	if (nn->nn_persistent_error || !nn->nn_sc_valid) {
+		ret = -ENOTCONN;
+		r2nm_node_put(node);
+		goto out;
+	}
+
+	if (free)
+		msg_type = RMSTR_TMEM_ASYNC_GET_AND_FREE_REQUEST;
+	else
+		msg_type = RMSTR_TMEM_ASYNC_GET_REQUEST;
+	ret = r2net_send_message_vec(msg_type, RMSTR_KEY,
+					vec, veclen, remotenode, &status);
+	r2nm_node_put(node);
+	if (ret < 0) {
+		if (ret == -ENOTCONN || ret == -EHOSTDOWN)
+			goto out;
+		if (ret == -EAGAIN)
+			goto out;
+		/* FIXME handle bad message possibilities here? */
+		pr_err("UNTESTED ret<0 in ramster_remote_async_get: ret=%d\n",
+				ret);
+	}
+	ret = status;
+out:
+	return ret;
+}
+
+#ifdef RAMSTER_TESTING
+/* leave me here to see if it catches a weird crash */
+static void ramster_check_irq_counts(void)
+{
+	static int last_hardirq_cnt, last_softirq_cnt, last_preempt_cnt;
+	int cur_hardirq_cnt, cur_softirq_cnt, cur_preempt_cnt;
+
+	cur_hardirq_cnt = hardirq_count() >> HARDIRQ_SHIFT;
+	if (cur_hardirq_cnt > last_hardirq_cnt) {
+		last_hardirq_cnt = cur_hardirq_cnt;
+		if (!(last_hardirq_cnt&(last_hardirq_cnt-1)))
+			pr_err("RAMSTER TESTING RRP hardirq_count=%d\n",
+				last_hardirq_cnt);
+	}
+	cur_softirq_cnt = softirq_count() >> SOFTIRQ_SHIFT;
+	if (cur_softirq_cnt > last_softirq_cnt) {
+		last_softirq_cnt = cur_softirq_cnt;
+		if (!(last_softirq_cnt&(last_softirq_cnt-1)))
+			pr_err("RAMSTER TESTING RRP softirq_count=%d\n",
+				last_softirq_cnt);
+	}
+	cur_preempt_cnt = preempt_count() & PREEMPT_MASK;
+	if (cur_preempt_cnt > last_preempt_cnt) {
+		last_preempt_cnt = cur_preempt_cnt;
+		if (!(last_preempt_cnt&(last_preempt_cnt-1)))
+			pr_err("RAMSTER TESTING RRP preempt_count=%d\n",
+				last_preempt_cnt);
+	}
+}
+#endif
+
+int r2net_remote_put(struct tmem_xhandle *xh, char *data, size_t size,
+				bool ephemeral, int *remotenode)
+{
+	int nodenum, ret = -1, status;
+	struct r2nm_node *node = NULL;
+	struct kvec vec[2];
+	size_t veclen = 2;
+	u32 msg_type;
+	struct r2net_node *nn;
+
+	BUG_ON(size > RMSTR_R2NET_MAX_LEN);
+	xh->client_id = r2nm_this_node(); /* which node is putting */
+	vec[0].iov_len = sizeof(*xh);
+	vec[0].iov_base = xh;
+	vec[1].iov_len = size;
+	vec[1].iov_base = data;
+
+	node = r2net_target_node;
+	if (!node)
+		goto out;
+
+	nodenum = r2net_target_nodenum;
+
+	r2nm_node_get(node);
+
+	nn = r2net_nn_from_num(nodenum);
+	if (nn->nn_persistent_error || !nn->nn_sc_valid) {
+		ret = -ENOTCONN;
+		r2nm_node_put(node);
+		goto out;
+	}
+
+	if (ephemeral)
+		msg_type = RMSTR_TMEM_PUT_EPH;
+	else
+		msg_type = RMSTR_TMEM_PUT_PERS;
+#ifdef RAMSTER_TESTING
+	/* leave me here to see if it catches a weird crash */
+	ramster_check_irq_counts();
+#endif
+
+	ret = r2net_send_message_vec(msg_type, RMSTR_KEY, vec, veclen,
+						nodenum, &status);
+	if (ret < 0)
+		ret = -1;
+	else {
+		ret = status;
+		*remotenode = nodenum;
+	}
+
+	r2nm_node_put(node);
+out:
+	return ret;
+}
+
+int r2net_remote_flush(struct tmem_xhandle *xh, int remotenode)
+{
+	int ret = -1, status;
+	struct r2nm_node *node = NULL;
+	struct kvec vec[1];
+	size_t veclen = 1;
+
+	node = r2nm_get_node_by_num(remotenode);
+	BUG_ON(node == NULL);
+	xh->client_id = r2nm_this_node(); /* which node is flushing */
+	vec[0].iov_len = sizeof(*xh);
+	vec[0].iov_base = xh;
+	BUG_ON(irqs_disabled());
+	BUG_ON(in_softirq());
+	ret = r2net_send_message_vec(RMSTR_TMEM_FLUSH, RMSTR_KEY,
+					vec, veclen, remotenode, &status);
+	r2nm_node_put(node);
+	return ret;
+}
+
+int r2net_remote_flush_object(struct tmem_xhandle *xh, int remotenode)
+{
+	int ret = -1, status;
+	struct r2nm_node *node = NULL;
+	struct kvec vec[1];
+	size_t veclen = 1;
+
+	node = r2nm_get_node_by_num(remotenode);
+	BUG_ON(node == NULL);
+	xh->client_id = r2nm_this_node(); /* which node is flobjing */
+	vec[0].iov_len = sizeof(*xh);
+	vec[0].iov_base = xh;
+	ret = r2net_send_message_vec(RMSTR_TMEM_FLOBJ, RMSTR_KEY,
+					vec, veclen, remotenode, &status);
+	r2nm_node_put(node);
+	return ret;
+}
+
+/*
+ * Handler registration
+ */
+
+static LIST_HEAD(r2net_unreg_list);
+
+static void r2net_unregister_handlers(void)
+{
+	r2net_unregister_handler_list(&r2net_unreg_list);
+}
+
+int r2net_register_handlers(void)
+{
+	int status;
+
+	status = r2net_register_handler(RMSTR_TMEM_PUT_EPH, RMSTR_KEY,
+				RMSTR_R2NET_MAX_LEN,
+				ramster_remote_put_handler,
+				NULL, NULL, &r2net_unreg_list);
+	if (status)
+		goto bail;
+
+	status = r2net_register_handler(RMSTR_TMEM_PUT_PERS, RMSTR_KEY,
+				RMSTR_R2NET_MAX_LEN,
+				ramster_remote_put_handler,
+				NULL, NULL, &r2net_unreg_list);
+	if (status)
+		goto bail;
+
+	status = r2net_register_handler(RMSTR_TMEM_ASYNC_GET_REQUEST, RMSTR_KEY,
+				RMSTR_R2NET_MAX_LEN,
+				ramster_remote_async_get_request_handler,
+				NULL, NULL,
+				&r2net_unreg_list);
+	if (status)
+		goto bail;
+
+	status = r2net_register_handler(RMSTR_TMEM_ASYNC_GET_AND_FREE_REQUEST,
+				RMSTR_KEY, RMSTR_R2NET_MAX_LEN,
+				ramster_remote_async_get_request_handler,
+				NULL, NULL,
+				&r2net_unreg_list);
+	if (status)
+		goto bail;
+
+	status = r2net_register_handler(RMSTR_TMEM_ASYNC_GET_REPLY, RMSTR_KEY,
+				RMSTR_R2NET_MAX_LEN,
+				ramster_remote_async_get_reply_handler,
+				NULL, NULL,
+				&r2net_unreg_list);
+	if (status)
+		goto bail;
+
+	status = r2net_register_handler(RMSTR_TMEM_FLUSH, RMSTR_KEY,
+				RMSTR_R2NET_MAX_LEN,
+				ramster_remote_flush_handler,
+				NULL, NULL,
+				&r2net_unreg_list);
+	if (status)
+		goto bail;
+
+	status = r2net_register_handler(RMSTR_TMEM_FLOBJ, RMSTR_KEY,
+				RMSTR_R2NET_MAX_LEN,
+				ramster_remote_flobj_handler,
+				NULL, NULL,
+				&r2net_unreg_list);
+	if (status)
+		goto bail;
+
+	pr_info("ramster: r2net handlers registered\n");
+
+bail:
+	if (status) {
+		r2net_unregister_handlers();
+		pr_err("ramster: couldn't register r2net handlers\n");
+	}
+	return status;
+}