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authorDavid Teigland <teigland@redhat.com>2006-01-18 04:30:29 -0500
committerSteven Whitehouse <swhiteho@redhat.com>2006-01-18 04:30:29 -0500
commite7fd41792fc0ee52a05fcaac87511f118328d147 (patch)
treeeee5227088ba97daef795e385b7548d2a1cc4cb6 /fs/dlm/midcomms.c
parente47314207032cfd1157b8c377df162839b32ea6f (diff)
[DLM] The core of the DLM for GFS2/CLVM
This is the core of the distributed lock manager which is required to use GFS2 as a cluster filesystem. It is also used by CLVM and can be used as a standalone lock manager independantly of either of these two projects. It implements VAX-style locking modes. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steve Whitehouse <swhiteho@redhat.com>
Diffstat (limited to 'fs/dlm/midcomms.c')
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1 files changed, 140 insertions, 0 deletions
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
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1/******************************************************************************
2*******************************************************************************
3**
4** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
5** Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
6**
7** This copyrighted material is made available to anyone wishing to use,
8** modify, copy, or redistribute it subject to the terms and conditions
9** of the GNU General Public License v.2.
10**
11*******************************************************************************
12******************************************************************************/
13
14/*
15 * midcomms.c
16 *
17 * This is the appallingly named "mid-level" comms layer.
18 *
19 * Its purpose is to take packets from the "real" comms layer,
20 * split them up into packets and pass them to the interested
21 * part of the locking mechanism.
22 *
23 * It also takes messages from the locking layer, formats them
24 * into packets and sends them to the comms layer.
25 */
26
27#include "dlm_internal.h"
28#include "lowcomms.h"
29#include "config.h"
30#include "rcom.h"
31#include "lock.h"
32#include "midcomms.h"
33
34
35static void copy_from_cb(void *dst, const void *base, unsigned offset,
36 unsigned len, unsigned limit)
37{
38 unsigned copy = len;
39
40 if ((copy + offset) > limit)
41 copy = limit - offset;
42 memcpy(dst, base + offset, copy);
43 len -= copy;
44 if (len)
45 memcpy(dst + copy, base, len);
46}
47
48/*
49 * Called from the low-level comms layer to process a buffer of
50 * commands.
51 *
52 * Only complete messages are processed here, any "spare" bytes from
53 * the end of a buffer are saved and tacked onto the front of the next
54 * message that comes in. I doubt this will happen very often but we
55 * need to be able to cope with it and I don't want the task to be waiting
56 * for packets to come in when there is useful work to be done.
57 */
58
59int dlm_process_incoming_buffer(int nodeid, const void *base,
60 unsigned offset, unsigned len, unsigned limit)
61{
62 unsigned char __tmp[DLM_INBUF_LEN];
63 struct dlm_header *msg = (struct dlm_header *) __tmp;
64 int ret = 0;
65 int err = 0;
66 uint16_t msglen;
67 uint32_t lockspace;
68
69 while (len > sizeof(struct dlm_header)) {
70
71 /* Copy just the header to check the total length. The
72 message may wrap around the end of the buffer back to the
73 start, so we need to use a temp buffer and copy_from_cb. */
74
75 copy_from_cb(msg, base, offset, sizeof(struct dlm_header),
76 limit);
77
78 msglen = le16_to_cpu(msg->h_length);
79 lockspace = msg->h_lockspace;
80
81 err = -EINVAL;
82 if (msglen < sizeof(struct dlm_header))
83 break;
84 err = -E2BIG;
85 if (msglen > dlm_config.buffer_size) {
86 log_print("message size %d from %d too big, buf len %d",
87 msglen, nodeid, len);
88 break;
89 }
90 err = 0;
91
92 /* If only part of the full message is contained in this
93 buffer, then do nothing and wait for lowcomms to call
94 us again later with more data. We return 0 meaning
95 we've consumed none of the input buffer. */
96
97 if (msglen > len)
98 break;
99
100 /* Allocate a larger temp buffer if the full message won't fit
101 in the buffer on the stack (which should work for most
102 ordinary messages). */
103
104 if (msglen > sizeof(__tmp) &&
105 msg == (struct dlm_header *) __tmp) {
106 msg = kmalloc(dlm_config.buffer_size, GFP_KERNEL);
107 if (msg == NULL)
108 return ret;
109 }
110
111 copy_from_cb(msg, base, offset, msglen, limit);
112
113 BUG_ON(lockspace != msg->h_lockspace);
114
115 ret += msglen;
116 offset += msglen;
117 offset &= (limit - 1);
118 len -= msglen;
119
120 switch (msg->h_cmd) {
121 case DLM_MSG:
122 dlm_receive_message(msg, nodeid, FALSE);
123 break;
124
125 case DLM_RCOM:
126 dlm_receive_rcom(msg, nodeid);
127 break;
128
129 default:
130 log_print("unknown msg type %x from %u: %u %u %u %u",
131 msg->h_cmd, nodeid, msglen, len, offset, ret);
132 }
133 }
134
135 if (msg != (struct dlm_header *) __tmp)
136 kfree(msg);
137
138 return err ? err : ret;
139}
140