1
2 /*
3 * Copyright (c) 2004 Daniel McNeil <daniel@osdl.org>
4 * 2004 Open Source Development Lab
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
13 * the GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18 *
19 * Module: .c
20 */
21
22 /*
23 * Change History:
24 *
25 * 2/2004 Marty Ridgeway (mridge@us.ibm.com) Changes to adapt to LTP
26 *
27 */
28 /*
29 * dio_append - append zeroed data to a file using O_DIRECT while
30 * a 2nd process is doing buffered reads and check if the buffer
31 * reads always see zero.
32 */
33 #define _GNU_SOURCE
34
35 #include <stdlib.h>
36 #include <sys/types.h>
37 #include <signal.h>
38 #include <fcntl.h>
39 #include <stdio.h>
40 #include <unistd.h>
41 #include <memory.h>
42 #include <limits.h>
43 #define NUM_CHILDREN 8
44
check_zero(unsigned char * buf,int size)45 char *check_zero(unsigned char *buf, int size)
46 {
47 unsigned char *p;
48
49 p = buf;
50
51 while (size > 0) {
52 if (*buf != 0) {
53 fprintf(stderr,
54 "non zero buffer at buf[%d] => 0x%02x,%02x,%02x,%02x\n",
55 buf - p, (unsigned int)buf[0],
56 size > 1 ? (unsigned int)buf[1] : 0,
57 size > 2 ? (unsigned int)buf[2] : 0,
58 size > 3 ? (unsigned int)buf[3] : 0);
59 fprintf(stderr, "buf %p, p %p\n", buf, p);
60 return buf;
61 }
62 buf++;
63 size--;
64 }
65 return 0; /* all zeros */
66 }
67
read_eof(char * filename)68 int read_eof(char *filename)
69 {
70 int fd;
71 int i;
72 int r;
73 char buf[4096];
74
75 while ((fd = open(filename, O_RDONLY)) < 0) {
76 sleep(1); /* wait for file to be created */
77 }
78
79 for (i = 0; i < 1000000; i++) {
80 off_t offset;
81 char *bufoff;
82
83 offset = lseek(fd, SEEK_END, 0);
84 r = read(fd, buf, 4096);
85 if (r > 0) {
86 if ((bufoff = check_zero(buf, r))) {
87 fprintf(stderr, "non-zero read at offset %p\n",
88 offset + bufoff);
89 exit(1);
90 }
91 }
92 }
93 return 0;
94 }
95
dio_append(char * filename)96 void dio_append(char *filename)
97 {
98 int fd;
99 void *bufptr;
100 int i;
101 int w;
102
103 fd = open(filename, O_DIRECT | O_WRONLY | O_CREAT, 0666);
104
105 if (fd < 0) {
106 perror("cannot create file");
107 return;
108 }
109
110 if (posix_memalign(&bufptr, 4096, 64 * 1024)) {
111 perror("cannot malloc aligned memory");
112 return;
113 }
114
115 memset(bufptr, 0, 64 * 1024);
116 for (i = 0; i < 1000; i++) {
117 if ((w = write(fd, bufptr, 64 * 1024)) != 64 * 1024) {
118 fprintf(stderr, "write %d returned %d\n", i, w);
119 }
120 }
121 }
122
main(int argc,char ** argv)123 int main(int argc, char **argv)
124 {
125 char filename[PATH_MAX];
126 int pid[NUM_CHILDREN];
127 int num_children = 1;
128 int i;
129
130 snprintf(filename, sizeof(filename), "%s/aiodio/file",
131 getenv("TMP") ? getenv("TMP") : "/tmp");
132
133 printf("Begin dio_append test...\n");
134
135 for (i = 0; i < num_children; i++) {
136 if ((pid[i] = fork()) == 0) {
137 /* child */
138 return read_eof(filename);
139 } else if (pid[i] < 0) {
140 /* error */
141 perror("fork error");
142 break;
143 } else {
144 /* Parent */
145 continue;
146 }
147 }
148
149 /*
150 * Parent appends to end of file using direct i/o
151 */
152
153 dio_append(filename);
154
155 for (i = 0; i < num_children; i++) {
156 kill(pid[i], SIGTERM);
157 }
158 return 0;
159 }
160