[linux-2.6-block.git] / fs / dlm / midcomms.c

// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
**
**
*******************************************************************************
******************************************************************************/

/*
 * midcomms.c
 *
 * This is the appallingly named "mid-level" comms layer.
 *
 * Its purpose is to take packets from the "real" comms layer,
 * split them up into packets and pass them to the interested
 * part of the locking mechanism.
 *
 * It also takes messages from the locking layer, formats them
 * into packets and sends them to the comms layer.
 */

#include "dlm_internal.h"
#include "lowcomms.h"
#include "config.h"
#include "lock.h"
#include "midcomms.h"


static void copy_from_cb(void *dst, const void *base, unsigned offset,
			 unsigned len, unsigned limit)
{
	unsigned copy = len;

	if ((copy + offset) > limit)
		copy = limit - offset;
	memcpy(dst, base + offset, copy);
	len -= copy;
	if (len)
		memcpy(dst + copy, base, len);
}

/*
 * Called from the low-level comms layer to process a buffer of
 * commands.
 *
 * Only complete messages are processed here, any "spare" bytes from
 * the end of a buffer are saved and tacked onto the front of the next
 * message that comes in. I doubt this will happen very often but we
 * need to be able to cope with it and I don't want the task to be waiting
 * for packets to come in when there is useful work to be done.
 */

int dlm_process_incoming_buffer(int nodeid, const void *base,
				unsigned offset, unsigned len, unsigned limit)
{
	union {
		unsigned char __buf[DLM_INBUF_LEN];
		/* this is to force proper alignment on some arches */
		union dlm_packet p;
	} __tmp;
	union dlm_packet *p = &__tmp.p;
	int ret = 0;
	int err = 0;
	uint16_t msglen;
	uint32_t lockspace;

	while (len > sizeof(struct dlm_header)) {

		/* Copy just the header to check the total length.  The
		   message may wrap around the end of the buffer back to the
		   start, so we need to use a temp buffer and copy_from_cb. */

		copy_from_cb(p, base, offset, sizeof(struct dlm_header),
			     limit);

		msglen = le16_to_cpu(p->header.h_length);
		lockspace = p->header.h_lockspace;

		err = -EINVAL;
		if (msglen < sizeof(struct dlm_header))
			break;
		if (p->header.h_cmd == DLM_MSG) {
			if (msglen < sizeof(struct dlm_message))
				break;
		} else {
			if (msglen < sizeof(struct dlm_rcom))
				break;
		}
		err = -E2BIG;
		if (msglen > dlm_config.ci_buffer_size) {
			log_print("message size %d from %d too big, buf len %d",
				  msglen, nodeid, len);
			break;
		}
		err = 0;

		/* If only part of the full message is contained in this
		   buffer, then do nothing and wait for lowcomms to call
		   us again later with more data.  We return 0 meaning
		   we've consumed none of the input buffer. */

		if (msglen > len)
			break;

		/* Allocate a larger temp buffer if the full message won't fit
		   in the buffer on the stack (which should work for most
		   ordinary messages). */

		if (msglen > sizeof(__tmp) && p == &__tmp.p) {
			p = kmalloc(dlm_config.ci_buffer_size, GFP_NOFS);
			if (p == NULL)
				return ret;
		}

		copy_from_cb(p, base, offset, msglen, limit);

		BUG_ON(lockspace != p->header.h_lockspace);

		ret += msglen;
		offset += msglen;
		offset &= (limit - 1);
		len -= msglen;

		dlm_receive_buffer(p, nodeid);
	}

	if (p != &__tmp.p)
		kfree(p);

	return err ? err : ret;
}
Commit	Line	Data
2522fe45	1	// SPDX-License-Identifier: GPL-2.0-only
e7fd4179 DT	2	/******************************************************************************
	3	*******************************************************************************
	4	**
	5	** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
e7847d35	6	** Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
e7fd4179	7	**
e7fd4179 DT	8	**
	9	*******************************************************************************
	10	******************************************************************************/
	11
	12	/*
	13	* midcomms.c
	14	*
	15	* This is the appallingly named "mid-level" comms layer.
	16	*
	17	* Its purpose is to take packets from the "real" comms layer,
	18	* split them up into packets and pass them to the interested
	19	* part of the locking mechanism.
	20	*
	21	* It also takes messages from the locking layer, formats them
	22	* into packets and sends them to the comms layer.
	23	*/
	24
	25	#include "dlm_internal.h"
	26	#include "lowcomms.h"
	27	#include "config.h"
e7fd4179 DT	28	#include "lock.h"
	29	#include "midcomms.h"
	30
	31
	32	static void copy_from_cb(void dst, const void base, unsigned offset,
	33	unsigned len, unsigned limit)
	34	{
	35	unsigned copy = len;
	36
	37	if ((copy + offset) > limit)
	38	copy = limit - offset;
	39	memcpy(dst, base + offset, copy);
	40	len -= copy;
	41	if (len)
	42	memcpy(dst + copy, base, len);
	43	}
	44
	45	/*
	46	* Called from the low-level comms layer to process a buffer of
	47	* commands.
	48	*
	49	* Only complete messages are processed here, any "spare" bytes from
	50	* the end of a buffer are saved and tacked onto the front of the next
	51	* message that comes in. I doubt this will happen very often but we
	52	* need to be able to cope with it and I don't want the task to be waiting
	53	* for packets to come in when there is useful work to be done.
	54	*/
	55
	56	int dlm_process_incoming_buffer(int nodeid, const void *base,
	57	unsigned offset, unsigned len, unsigned limit)
	58	{
e7847d35 FDN	59	union {
	60	unsigned char __buf[DLM_INBUF_LEN];
	61	/* this is to force proper alignment on some arches */
eef7d739	62	union dlm_packet p;
e7847d35	63	} __tmp;
eef7d739	64	union dlm_packet *p = &__tmp.p;
e7fd4179 DT	65	int ret = 0;
	66	int err = 0;
	67	uint16_t msglen;
	68	uint32_t lockspace;
	69
	70	while (len > sizeof(struct dlm_header)) {
	71
	72	/* Copy just the header to check the total length. The
	73	message may wrap around the end of the buffer back to the
	74	start, so we need to use a temp buffer and copy_from_cb. */
	75
eef7d739	76	copy_from_cb(p, base, offset, sizeof(struct dlm_header),
e7fd4179 DT	77	limit);
e7fd4179 DT	78
eef7d739 AV	79	msglen = le16_to_cpu(p->header.h_length);
eef7d739 AV	80	lockspace = p->header.h_lockspace;
e7fd4179 DT	81
	82	err = -EINVAL;
	83	if (msglen < sizeof(struct dlm_header))
	84	break;
eef7d739 AV	85	if (p->header.h_cmd == DLM_MSG) {
	86	if (msglen < sizeof(struct dlm_message))
	87	break;
	88	} else {
	89	if (msglen < sizeof(struct dlm_rcom))
	90	break;
	91	}
e7fd4179	92	err = -E2BIG;
68c817a1	93	if (msglen > dlm_config.ci_buffer_size) {
e7fd4179 DT	94	log_print("message size %d from %d too big, buf len %d",
	95	msglen, nodeid, len);
	96	break;
	97	}
	98	err = 0;
	99
	100	/* If only part of the full message is contained in this
	101	buffer, then do nothing and wait for lowcomms to call
	102	us again later with more data. We return 0 meaning
	103	we've consumed none of the input buffer. */
	104
	105	if (msglen > len)
	106	break;
	107
	108	/* Allocate a larger temp buffer if the full message won't fit
	109	in the buffer on the stack (which should work for most
	110	ordinary messages). */
	111
eef7d739	112	if (msglen > sizeof(__tmp) && p == &__tmp.p) {
d6d7b702	113	p = kmalloc(dlm_config.ci_buffer_size, GFP_NOFS);
eef7d739	114	if (p == NULL)
e7fd4179 DT	115	return ret;
	116	}
	117
eef7d739	118	copy_from_cb(p, base, offset, msglen, limit);
e7fd4179	119
eef7d739	120	BUG_ON(lockspace != p->header.h_lockspace);
e7fd4179 DT	121
	122	ret += msglen;
	123	offset += msglen;
	124	offset &= (limit - 1);
	125	len -= msglen;
	126
eef7d739	127	dlm_receive_buffer(p, nodeid);
e7fd4179 DT	128	}
e7fd4179 DT	129
eef7d739 AV	130	if (p != &__tmp.p)
eef7d739 AV	131	kfree(p);
e7fd4179 DT	132
	133	return err ? err : ret;
	134	}
	135