root / block.c @ 97eb5b14
History | View | Annotate | Download (9.6 kB)
1 |
/*
|
---|---|
2 |
* QEMU System Emulator block driver
|
3 |
*
|
4 |
* Copyright (c) 2003 Fabrice Bellard
|
5 |
*
|
6 |
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
7 |
* of this software and associated documentation files (the "Software"), to deal
|
8 |
* in the Software without restriction, including without limitation the rights
|
9 |
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
10 |
* copies of the Software, and to permit persons to whom the Software is
|
11 |
* furnished to do so, subject to the following conditions:
|
12 |
*
|
13 |
* The above copyright notice and this permission notice shall be included in
|
14 |
* all copies or substantial portions of the Software.
|
15 |
*
|
16 |
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
17 |
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
18 |
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
19 |
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
20 |
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
21 |
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
22 |
* THE SOFTWARE.
|
23 |
*/
|
24 |
#include <stdlib.h> |
25 |
#include <stdio.h> |
26 |
#include <stdarg.h> |
27 |
#include <string.h> |
28 |
#include <getopt.h> |
29 |
#include <inttypes.h> |
30 |
#include <unistd.h> |
31 |
#include <sys/mman.h> |
32 |
#include <fcntl.h> |
33 |
#include <signal.h> |
34 |
#include <time.h> |
35 |
#include <sys/time.h> |
36 |
#include <malloc.h> |
37 |
#include <termios.h> |
38 |
#include <sys/poll.h> |
39 |
#include <errno.h> |
40 |
#include <sys/wait.h> |
41 |
#include <netinet/in.h> |
42 |
|
43 |
#include "vl.h" |
44 |
|
45 |
#define NO_THUNK_TYPE_SIZE
|
46 |
#include "thunk.h" |
47 |
|
48 |
struct BlockDriverState {
|
49 |
int fd; /* if -1, only COW mappings */ |
50 |
int64_t total_sectors; |
51 |
int read_only;
|
52 |
|
53 |
uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */
|
54 |
uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */
|
55 |
int cow_bitmap_size;
|
56 |
int cow_fd;
|
57 |
int64_t cow_sectors_offset; |
58 |
int boot_sector_enabled;
|
59 |
uint8_t boot_sector_data[512];
|
60 |
|
61 |
char filename[1024]; |
62 |
}; |
63 |
|
64 |
BlockDriverState *bdrv_open(const char *filename, int snapshot) |
65 |
{ |
66 |
BlockDriverState *bs; |
67 |
int fd, cow_fd;
|
68 |
int64_t size; |
69 |
char template[] = "/tmp/vl.XXXXXX"; |
70 |
struct cow_header_v2 cow_header;
|
71 |
struct stat st;
|
72 |
|
73 |
bs = malloc(sizeof(BlockDriverState));
|
74 |
if(!bs)
|
75 |
return NULL; |
76 |
bs->read_only = 0;
|
77 |
bs->fd = -1;
|
78 |
bs->cow_fd = -1;
|
79 |
bs->cow_bitmap = NULL;
|
80 |
strcpy(bs->filename, filename); |
81 |
|
82 |
/* open standard HD image */
|
83 |
fd = open(filename, O_RDWR | O_LARGEFILE); |
84 |
if (fd < 0) { |
85 |
/* read only image on disk */
|
86 |
fd = open(filename, O_RDONLY | O_LARGEFILE); |
87 |
if (fd < 0) { |
88 |
perror(filename); |
89 |
goto fail;
|
90 |
} |
91 |
if (!snapshot)
|
92 |
bs->read_only = 1;
|
93 |
} |
94 |
bs->fd = fd; |
95 |
|
96 |
/* see if it is a cow image */
|
97 |
if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) { |
98 |
fprintf(stderr, "%s: could not read header\n", filename);
|
99 |
goto fail;
|
100 |
} |
101 |
if (cow_header.magic == htonl(COW_MAGIC) &&
|
102 |
cow_header.version == htonl(COW_VERSION)) { |
103 |
/* cow image found */
|
104 |
size = cow_header.size; |
105 |
#ifndef WORDS_BIGENDIAN
|
106 |
size = bswap64(size); |
107 |
#endif
|
108 |
bs->total_sectors = size / 512;
|
109 |
|
110 |
bs->cow_fd = fd; |
111 |
bs->fd = -1;
|
112 |
if (cow_header.backing_file[0] != '\0') { |
113 |
if (stat(cow_header.backing_file, &st) != 0) { |
114 |
fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file);
|
115 |
goto fail;
|
116 |
} |
117 |
if (st.st_mtime != htonl(cow_header.mtime)) {
|
118 |
fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file);
|
119 |
goto fail;
|
120 |
} |
121 |
fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE); |
122 |
if (fd < 0) |
123 |
goto fail;
|
124 |
bs->fd = fd; |
125 |
} |
126 |
/* mmap the bitmap */
|
127 |
bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header); |
128 |
bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), |
129 |
bs->cow_bitmap_size, |
130 |
PROT_READ | PROT_WRITE, |
131 |
MAP_SHARED, bs->cow_fd, 0);
|
132 |
if (bs->cow_bitmap_addr == MAP_FAILED)
|
133 |
goto fail;
|
134 |
bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header);
|
135 |
bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511; |
136 |
snapshot = 0;
|
137 |
} else {
|
138 |
/* standard raw image */
|
139 |
size = lseek64(fd, 0, SEEK_END);
|
140 |
bs->total_sectors = size / 512;
|
141 |
bs->fd = fd; |
142 |
} |
143 |
|
144 |
if (snapshot) {
|
145 |
/* create a temporary COW file */
|
146 |
cow_fd = mkstemp(template); |
147 |
if (cow_fd < 0) |
148 |
goto fail;
|
149 |
bs->cow_fd = cow_fd; |
150 |
unlink(template); |
151 |
|
152 |
/* just need to allocate bitmap */
|
153 |
bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3; |
154 |
bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), |
155 |
bs->cow_bitmap_size, |
156 |
PROT_READ | PROT_WRITE, |
157 |
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
158 |
if (bs->cow_bitmap_addr == MAP_FAILED)
|
159 |
goto fail;
|
160 |
bs->cow_bitmap = bs->cow_bitmap_addr; |
161 |
bs->cow_sectors_offset = 0;
|
162 |
} |
163 |
|
164 |
return bs;
|
165 |
fail:
|
166 |
bdrv_close(bs); |
167 |
return NULL; |
168 |
} |
169 |
|
170 |
void bdrv_close(BlockDriverState *bs)
|
171 |
{ |
172 |
/* we unmap the mapping so that it is written to the COW file */
|
173 |
if (bs->cow_bitmap_addr)
|
174 |
munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size); |
175 |
if (bs->cow_fd >= 0) |
176 |
close(bs->cow_fd); |
177 |
if (bs->fd >= 0) |
178 |
close(bs->fd); |
179 |
free(bs); |
180 |
} |
181 |
|
182 |
static inline void set_bit(uint8_t *bitmap, int64_t bitnum) |
183 |
{ |
184 |
bitmap[bitnum / 8] |= (1 << (bitnum%8)); |
185 |
} |
186 |
|
187 |
static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum) |
188 |
{ |
189 |
return !!(bitmap[bitnum / 8] & (1 << (bitnum%8))); |
190 |
} |
191 |
|
192 |
|
193 |
/* Return true if first block has been changed (ie. current version is
|
194 |
* in COW file). Set the number of continuous blocks for which that
|
195 |
* is true. */
|
196 |
static int is_changed(uint8_t *bitmap, |
197 |
int64_t sector_num, int nb_sectors,
|
198 |
int *num_same)
|
199 |
{ |
200 |
int changed;
|
201 |
|
202 |
if (!bitmap || nb_sectors == 0) { |
203 |
*num_same = nb_sectors; |
204 |
return 0; |
205 |
} |
206 |
|
207 |
changed = is_bit_set(bitmap, sector_num); |
208 |
for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) { |
209 |
if (is_bit_set(bitmap, sector_num + *num_same) != changed)
|
210 |
break;
|
211 |
} |
212 |
|
213 |
return changed;
|
214 |
} |
215 |
|
216 |
/* commit COW file into the raw image */
|
217 |
int bdrv_commit(BlockDriverState *bs)
|
218 |
{ |
219 |
int64_t i; |
220 |
uint8_t *cow_bitmap; |
221 |
|
222 |
if (!bs->cow_bitmap) {
|
223 |
fprintf(stderr, "Already committed to %s\n", bs->filename);
|
224 |
return 0; |
225 |
} |
226 |
|
227 |
if (bs->read_only) {
|
228 |
fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename);
|
229 |
return -1; |
230 |
} |
231 |
|
232 |
cow_bitmap = bs->cow_bitmap; |
233 |
for (i = 0; i < bs->total_sectors; i++) { |
234 |
if (is_bit_set(cow_bitmap, i)) {
|
235 |
unsigned char sector[512]; |
236 |
if (bdrv_read(bs, i, sector, 1) != 0) { |
237 |
fprintf(stderr, "Error reading sector %lli: aborting commit\n",
|
238 |
(long long)i); |
239 |
return -1; |
240 |
} |
241 |
|
242 |
/* Make bdrv_write write to real file for a moment. */
|
243 |
bs->cow_bitmap = NULL;
|
244 |
if (bdrv_write(bs, i, sector, 1) != 0) { |
245 |
fprintf(stderr, "Error writing sector %lli: aborting commit\n",
|
246 |
(long long)i); |
247 |
bs->cow_bitmap = cow_bitmap; |
248 |
return -1; |
249 |
} |
250 |
bs->cow_bitmap = cow_bitmap; |
251 |
} |
252 |
} |
253 |
fprintf(stderr, "Committed snapshot to %s\n", bs->filename);
|
254 |
return 0; |
255 |
} |
256 |
|
257 |
/* return -1 if error */
|
258 |
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
|
259 |
uint8_t *buf, int nb_sectors)
|
260 |
{ |
261 |
int ret, n, fd;
|
262 |
int64_t offset; |
263 |
|
264 |
while (nb_sectors > 0) { |
265 |
if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {
|
266 |
fd = bs->cow_fd; |
267 |
offset = bs->cow_sectors_offset; |
268 |
} else if (sector_num == 0 && bs->boot_sector_enabled) { |
269 |
memcpy(buf, bs->boot_sector_data, 512);
|
270 |
n = 1;
|
271 |
goto next;
|
272 |
} else {
|
273 |
fd = bs->fd; |
274 |
offset = 0;
|
275 |
} |
276 |
|
277 |
if (fd < 0) { |
278 |
/* no file, just return empty sectors */
|
279 |
memset(buf, 0, n * 512); |
280 |
} else {
|
281 |
offset += sector_num * 512;
|
282 |
lseek64(fd, offset, SEEK_SET); |
283 |
ret = read(fd, buf, n * 512);
|
284 |
if (ret != n * 512) { |
285 |
return -1; |
286 |
} |
287 |
} |
288 |
next:
|
289 |
nb_sectors -= n; |
290 |
sector_num += n; |
291 |
buf += n * 512;
|
292 |
} |
293 |
return 0; |
294 |
} |
295 |
|
296 |
/* return -1 if error */
|
297 |
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
|
298 |
const uint8_t *buf, int nb_sectors) |
299 |
{ |
300 |
int ret, fd, i;
|
301 |
int64_t offset, retl; |
302 |
|
303 |
if (bs->read_only)
|
304 |
return -1; |
305 |
|
306 |
if (bs->cow_bitmap) {
|
307 |
fd = bs->cow_fd; |
308 |
offset = bs->cow_sectors_offset; |
309 |
} else {
|
310 |
fd = bs->fd; |
311 |
offset = 0;
|
312 |
} |
313 |
|
314 |
offset += sector_num * 512;
|
315 |
retl = lseek64(fd, offset, SEEK_SET); |
316 |
if (retl == -1) { |
317 |
return -1; |
318 |
} |
319 |
ret = write(fd, buf, nb_sectors * 512);
|
320 |
if (ret != nb_sectors * 512) { |
321 |
return -1; |
322 |
} |
323 |
|
324 |
if (bs->cow_bitmap) {
|
325 |
for (i = 0; i < nb_sectors; i++) |
326 |
set_bit(bs->cow_bitmap, sector_num + i); |
327 |
} |
328 |
return 0; |
329 |
} |
330 |
|
331 |
void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)
|
332 |
{ |
333 |
*nb_sectors_ptr = bs->total_sectors; |
334 |
} |
335 |
|
336 |
/* force a given boot sector. */
|
337 |
void bdrv_set_boot_sector(BlockDriverState *bs, const uint8_t *data, int size) |
338 |
{ |
339 |
bs->boot_sector_enabled = 1;
|
340 |
if (size > 512) |
341 |
size = 512;
|
342 |
memcpy(bs->boot_sector_data, data, size); |
343 |
memset(bs->boot_sector_data + size, 0, 512 - size); |
344 |
} |