1 /*
2 * Copyright 2010 by Garmin Ltd. or its subsidiaries
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 *
16 * Performs a simple write/readback test to verify correct functionality
17 * of direct i/o on a block device node.
18 */
19
20 /* For large-file support */
21 #define _FILE_OFFSET_BITS 64
22 #define _LARGEFILE_SOURCE
23 #define _LARGEFILE64_SOURCE
24
25 /* For O_DIRECT */
26 #define _GNU_SOURCE
27
28 #include <ctype.h>
29 #include <errno.h>
30 #include <fcntl.h>
31 #include <inttypes.h>
32 #include <limits.h>
33 #include <stdint.h>
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <sys/ioctl.h>
38 #include <sys/mman.h>
39 #include <sys/stat.h>
40 #include <sys/types.h>
41 #include <unistd.h>
42
43 #include <linux/fs.h>
44
45 #define NUM_TEST_BLKS 128
46
47 /*
48 * Allocate page-aligned memory. Could use posix_memalign(3), but some
49 * systems don't support it. Also pre-faults memory since we'll be using
50 * it all right away anyway.
51 */
pagealign_alloc(size_t size)52 static void *pagealign_alloc(size_t size)
53 {
54 void *ret = mmap(NULL, size, PROT_READ | PROT_WRITE,
55 MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE | MAP_LOCKED,
56 -1, 0);
57 if (ret == MAP_FAILED) {
58 perror("mmap");
59 ret = NULL;
60 }
61 return ret;
62 }
63
pagealign_free(void * addr,size_t size)64 static void pagealign_free(void *addr, size_t size)
65 {
66 int ret = munmap(addr, size);
67 if (ret == -1)
68 perror("munmap");
69 }
70
do_read(int fd,void * buf,off64_t start,size_t count)71 static ssize_t do_read(int fd, void *buf, off64_t start, size_t count)
72 {
73 ssize_t ret;
74 size_t bytes_read = 0;
75
76 lseek64(fd, start, SEEK_SET);
77
78 do {
79 ret = read(fd, (char *)buf + bytes_read, count - bytes_read);
80 if (ret == -1) {
81 perror("read");
82 return -1;
83 } else if (ret == 0) {
84 fprintf(stderr, "Unexpected end-of-file\n");
85 return -1;
86 }
87 bytes_read += ret;
88 } while (bytes_read < count);
89
90 return bytes_read;
91 }
92
do_write(int fd,const void * buf,off64_t start,size_t count)93 static ssize_t do_write(int fd, const void *buf, off64_t start, size_t count)
94 {
95 ssize_t ret;
96 size_t bytes_out = 0;
97
98 lseek64(fd, start, SEEK_SET);
99
100 do {
101 ret = write(fd, (char *)buf + bytes_out, count - bytes_out);
102 if (ret == -1) {
103 perror("write");
104 return -1;
105 } else if (ret == 0) {
106 fprintf(stderr, "write returned 0\n");
107 return -1;
108 }
109 bytes_out += ret;
110 } while (bytes_out < count);
111
112 return bytes_out;
113 }
114
115 /*
116 * Initializes test buffer with locally-unique test pattern. High 16-bits of
117 * each 32-bit word contain first disk block number of the test area, low
118 * 16-bits contain word offset into test area. The goal is that a given test
119 * area should never contain the same data as a nearby test area, and that the
120 * data for a given test area be easily reproducable given the start block and
121 * test area size.
122 */
init_test_buf(void * buf,uint64_t start_blk,size_t len)123 static void init_test_buf(void *buf, uint64_t start_blk, size_t len)
124 {
125 uint32_t *data = buf;
126 size_t i;
127
128 len /= sizeof(uint32_t);
129 for (i = 0; i < len; i++)
130 data[i] = (start_blk & 0xFFFF) << 16 | (i & 0xFFFF);
131 }
132
dump_hex(const void * buf,int len)133 static void dump_hex(const void *buf, int len)
134 {
135 const uint8_t *data = buf;
136 int i;
137 char ascii_buf[17];
138
139 ascii_buf[16] = '\0';
140
141 for (i = 0; i < len; i++) {
142 int val = data[i];
143 int off = i % 16;
144
145 if (off == 0)
146 printf("%08x ", i);
147 printf("%02x ", val);
148 ascii_buf[off] = isprint(val) ? val : '.';
149 if (off == 15)
150 printf(" %-16s\n", ascii_buf);
151 }
152
153 i %= 16;
154 if (i) {
155 ascii_buf[i] = '\0';
156 while (i++ < 16)
157 printf(" ");
158 printf(" %-16s\n", ascii_buf);
159 }
160 }
161
update_progress(int current,int total)162 static void update_progress(int current, int total)
163 {
164 double pct_done = (double)current * 100 / total;
165 printf("Testing area %d/%d (%6.2f%% complete)\r", current, total,
166 pct_done);
167 fflush(stdout);
168 }
169
main(int argc,const char * argv[])170 int main(int argc, const char *argv[])
171 {
172 int ret = 1;
173 const char *path;
174 int fd;
175 struct stat stat;
176 void *read_buf = NULL, *write_buf = NULL;
177 int blk_size;
178 uint64_t num_blks;
179 size_t test_size;
180 int test_areas, i;
181
182 if (argc != 2) {
183 printf("Usage: directiotest blkdev_path\n");
184 exit(1);
185 }
186
187 path = argv[1];
188 fd = open(path, O_RDWR | O_DIRECT | O_LARGEFILE);
189 if (fd == -1) {
190 perror("open");
191 exit(1);
192 }
193 if (fstat(fd, &stat) == -1) {
194 perror("stat");
195 goto cleanup;
196 } else if (!S_ISBLK(stat.st_mode)) {
197 fprintf(stderr, "%s is not a block device\n", path);
198 goto cleanup;
199 }
200
201 if (ioctl(fd, BLKSSZGET, &blk_size) == -1) {
202 perror("ioctl");
203 goto cleanup;
204 }
205 if (ioctl(fd, BLKGETSIZE64, &num_blks) == -1) {
206 perror("ioctl");
207 goto cleanup;
208 }
209 num_blks /= blk_size;
210
211 test_size = (size_t)blk_size * NUM_TEST_BLKS;
212 read_buf = pagealign_alloc(test_size);
213 write_buf = pagealign_alloc(test_size);
214 if (!read_buf || !write_buf) {
215 fprintf(stderr, "Error allocating test buffers\n");
216 goto cleanup;
217 }
218
219 /*
220 * Start the actual test. Go through the entire device, writing
221 * locally-unique patern to each test block and then reading it
222 * back.
223 */
224 if (num_blks / NUM_TEST_BLKS > INT_MAX) {
225 printf("Warning: Device too large for test variables\n");
226 printf("Entire device will not be tested\n");
227 test_areas = INT_MAX;
228 } else {
229 test_areas = num_blks / NUM_TEST_BLKS;
230 }
231
232 printf("Starting test\n");
233
234 for (i = 0; i < test_areas; i++) {
235 uint64_t cur_blk = (uint64_t)i * NUM_TEST_BLKS;
236
237 update_progress(i + 1, test_areas);
238
239 init_test_buf(write_buf, cur_blk, test_size);
240
241 if (do_write(fd, write_buf, cur_blk * blk_size, test_size) !=
242 (ssize_t)test_size) {
243 fprintf(stderr, "write failed, aborting test\n");
244 goto cleanup;
245 }
246 if (do_read(fd, read_buf, cur_blk * blk_size, test_size) !=
247 (ssize_t)test_size) {
248 fprintf(stderr, "read failed, aborting test\n");
249 goto cleanup;
250 }
251
252 if (memcmp(write_buf, read_buf, test_size)) {
253 printf("Readback verification failed at block %" PRIu64 "\n\n",
254 cur_blk);
255 printf("Written data:\n");
256 dump_hex(write_buf, test_size);
257 printf("\nRead data:\n");
258 dump_hex(read_buf, test_size);
259 goto cleanup;
260 }
261 }
262
263 printf("\nTest complete\n");
264 ret = 0;
265
266 cleanup:
267 if (read_buf)
268 pagealign_free(read_buf, test_size);
269 if (write_buf)
270 pagealign_free(write_buf, test_size);
271 close(fd);
272 return ret;
273 }
274