1 /*-
2 * Copyright (c) 2006, Stephan Uphoff <ups@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27
28 #include <sys/types.h>
29 #include <unistd.h>
30 #include <sys/stat.h>
31 #include <fcntl.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <sys/mman.h>
35
36
37 int prepareFile(const char* filename,int* fdp);
38 int mapBuffer(char** bufferp,int fd1,int fd2);
39 int startIO(int fd,char *buffer);
40
41 static int pagesize;
42
43 #define FILESIZE (32*1024)
44 static char wbuffer[FILESIZE];
45
46 /* Create a FILESIZE sized file - then remove file data from the cache*/
prepareFile(const char * filename,int * fdp)47 int prepareFile(const char* filename,int* fdp)
48 {
49 int fd;
50 int len;
51 int status;
52 void *addr;
53
54 fd = open(filename,O_CREAT | O_TRUNC | O_RDWR,S_IRWXU);
55 if (fd == -1)
56 {
57 perror("Creating file");
58 return fd;
59 }
60
61 len = write(fd,wbuffer,FILESIZE);
62 if (len < 0)
63 {
64 perror("Write failed");
65 return 1;
66 }
67
68 status = fsync(fd);
69 if (status != 0)
70 {
71 perror("fsync failed");
72 return 1;
73 }
74
75 addr = mmap(NULL,FILESIZE, PROT_READ | PROT_WRITE , MAP_SHARED, fd, 0);
76 if (addr == MAP_FAILED)
77 {
78 perror("Mmap failed");
79 return 1;
80 }
81
82 status = msync(addr,FILESIZE,MS_INVALIDATE | MS_SYNC);
83 if (status != 0)
84 {
85 perror("Msync failed");
86 return 1;
87 }
88
89 munmap(addr,FILESIZE);
90
91 *fdp = fd;
92 return 0;
93 }
94
95
96 /* mmap a 2 page buffer - first page is from fd1, second page from fd2 */
mapBuffer(char ** bufferp,int fd1,int fd2)97 int mapBuffer(char** bufferp,int fd1,int fd2)
98 {
99 void* addr;
100 char *buffer;
101
102 addr = mmap(NULL,pagesize*2, PROT_READ | PROT_WRITE , MAP_SHARED, fd1, 0);
103 if (addr == MAP_FAILED)
104 {
105 perror("Mmap failed");
106 return 1;
107 }
108
109 buffer = addr;
110 addr = mmap(buffer + pagesize,pagesize, PROT_READ | PROT_WRITE , MAP_FIXED |
111 MAP_SHARED, fd2, 0);
112
113 if (addr == MAP_FAILED)
114 {
115 perror("Mmap2 failed");
116 return 1;
117 }
118 *bufferp = buffer;
119 return 0;
120 }
121
122
startIO(int fd,char * buffer)123 int startIO(int fd,char *buffer)
124 {
125 ssize_t len;
126 len = write(fd,buffer,2*pagesize);
127 if (len == -1)
128 {
129 perror("write failed");
130 return 1;
131 }
132 return 0;
133 }
134
135
main(int argc __unused,char * argv[]__unused)136 int main(int argc __unused, char *argv[] __unused)
137 {
138
139 int fdA,fdB,fdDelayA,fdDelayB;
140 int status;
141 char *bufferA,*bufferB;
142 pid_t pid;
143
144 pagesize = getpagesize();
145
146 if ((prepareFile("A",&fdA))
147 || (prepareFile("B",&fdB))
148 || (prepareFile("DelayA",&fdDelayA))
149 || (prepareFile("DelayB",&fdDelayB))
150 || (mapBuffer(&bufferA,fdDelayA,fdB))
151 || (mapBuffer(&bufferB,fdDelayB,fdA)))
152 exit(1);
153
154 pid = fork();
155
156 if (pid == 0)
157 {
158 status = startIO(fdA,bufferA);
159 exit(status);
160 }
161
162 if (pid == -1)
163 {
164 exit(1);
165 }
166 status = startIO(fdB,bufferB);
167 exit(status);
168
169 }
170
171
172
173
174
175