Revision 33e3963e block.c
| b/block.c | ||
|---|---|---|
| 38 | 38 |
#include <sys/poll.h> |
| 39 | 39 |
#include <errno.h> |
| 40 | 40 |
#include <sys/wait.h> |
| 41 |
#include <netinet/in.h> |
|
| 41 | 42 |
|
| 42 | 43 |
#include "vl.h" |
| 43 | 44 |
|
| 45 |
#define NO_THUNK_TYPE_SIZE |
|
| 46 |
#include "thunk.h" |
|
| 47 |
|
|
| 44 | 48 |
struct BlockDriverState {
|
| 45 |
int fd; |
|
| 49 |
int fd; /* if -1, only COW mappings */
|
|
| 46 | 50 |
int64_t total_sectors; |
| 47 | 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 |
char filename[1024]; |
|
| 48 | 59 |
}; |
| 49 | 60 |
|
| 50 |
BlockDriverState *bdrv_open(const char *filename) |
|
| 61 |
BlockDriverState *bdrv_open(const char *filename, int snapshot)
|
|
| 51 | 62 |
{
|
| 52 | 63 |
BlockDriverState *bs; |
| 53 |
int fd; |
|
| 64 |
int fd, cow_fd;
|
|
| 54 | 65 |
int64_t size; |
| 66 |
char template[] = "/tmp/vl.XXXXXX"; |
|
| 67 |
struct cow_header_v2 cow_header; |
|
| 68 |
struct stat st; |
|
| 55 | 69 |
|
| 56 | 70 |
bs = malloc(sizeof(BlockDriverState)); |
| 57 | 71 |
if(!bs) |
| 58 | 72 |
return NULL; |
| 59 | 73 |
bs->read_only = 0; |
| 60 |
fd = open(filename, O_RDWR); |
|
| 74 |
bs->fd = -1; |
|
| 75 |
bs->cow_fd = -1; |
|
| 76 |
bs->cow_bitmap = NULL; |
|
| 77 |
strcpy(bs->filename, filename); |
|
| 78 |
|
|
| 79 |
/* open standard HD image */ |
|
| 80 |
fd = open(filename, O_RDWR | O_LARGEFILE); |
|
| 61 | 81 |
if (fd < 0) {
|
| 62 |
fd = open(filename, O_RDONLY); |
|
| 82 |
/* read only image on disk */ |
|
| 83 |
fd = open(filename, O_RDONLY | O_LARGEFILE); |
|
| 63 | 84 |
if (fd < 0) {
|
| 64 |
close(fd); |
|
| 65 |
free(bs); |
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| 66 |
return NULL; |
|
| 85 |
perror(filename); |
|
| 86 |
goto fail; |
|
| 67 | 87 |
} |
| 68 |
bs->read_only = 1; |
|
| 88 |
if (!snapshot) |
|
| 89 |
bs->read_only = 1; |
|
| 69 | 90 |
} |
| 70 |
size = lseek64(fd, 0, SEEK_END); |
|
| 71 |
bs->total_sectors = size / 512; |
|
| 72 | 91 |
bs->fd = fd; |
| 92 |
|
|
| 93 |
/* see if it is a cow image */ |
|
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if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
|
|
| 95 |
fprintf(stderr, "%s: could not read header\n", filename); |
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goto fail; |
|
| 97 |
} |
|
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if (cow_header.magic == htonl(COW_MAGIC) && |
|
| 99 |
cow_header.version == htonl(COW_VERSION)) {
|
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/* cow image found */ |
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size = cow_header.size; |
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#ifndef WORDS_BIGENDIAN |
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size = bswap64(size); |
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#endif |
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bs->total_sectors = size / 512; |
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|
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bs->cow_fd = fd; |
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bs->fd = -1; |
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if (cow_header.backing_file[0] != '\0') {
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if (stat(cow_header.backing_file, &st) != 0) {
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fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file); |
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goto fail; |
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} |
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if (st.st_mtime != htonl(cow_header.mtime)) {
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fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file); |
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goto fail; |
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} |
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fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE); |
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if (fd < 0) |
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goto fail; |
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bs->fd = fd; |
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} |
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/* mmap the bitmap */ |
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bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header); |
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bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), |
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bs->cow_bitmap_size, |
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PROT_READ | PROT_WRITE, |
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MAP_SHARED, bs->cow_fd, 0); |
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if (bs->cow_bitmap_addr == MAP_FAILED) |
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goto fail; |
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bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header); |
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bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511; |
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snapshot = 0; |
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} else {
|
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/* standard raw image */ |
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size = lseek64(fd, 0, SEEK_END); |
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bs->total_sectors = size / 512; |
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bs->fd = fd; |
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} |
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|
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if (snapshot) {
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/* create a temporary COW file */ |
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cow_fd = mkstemp(template); |
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if (cow_fd < 0) |
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goto fail; |
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bs->cow_fd = cow_fd; |
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unlink(template); |
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|
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/* just need to allocate bitmap */ |
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bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3; |
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bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), |
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bs->cow_bitmap_size, |
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PROT_READ | PROT_WRITE, |
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
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if (bs->cow_bitmap_addr == MAP_FAILED) |
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goto fail; |
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bs->cow_bitmap = bs->cow_bitmap_addr; |
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bs->cow_sectors_offset = 0; |
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} |
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|
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return bs; |
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fail: |
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bdrv_close(bs); |
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return NULL; |
|
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} |
| 75 | 166 |
|
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void bdrv_close(BlockDriverState *bs) |
| 77 | 168 |
{
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close(bs->fd); |
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/* we unmap the mapping so that it is written to the COW file */ |
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if (bs->cow_bitmap_addr) |
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munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size); |
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if (bs->cow_fd >= 0) |
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close(bs->cow_fd); |
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if (bs->fd >= 0) |
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close(bs->fd); |
|
| 79 | 176 |
free(bs); |
| 80 | 177 |
} |
| 81 | 178 |
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static inline void set_bit(uint8_t *bitmap, int64_t bitnum) |
|
| 180 |
{
|
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| 181 |
bitmap[bitnum / 8] |= (1 << (bitnum%8)); |
|
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} |
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|
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static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum) |
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{
|
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return !!(bitmap[bitnum / 8] & (1 << (bitnum%8))); |
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} |
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|
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| 189 |
|
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/* Return true if first block has been changed (ie. current version is |
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* in COW file). Set the number of continuous blocks for which that |
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| 192 |
* is true. */ |
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static int is_changed(uint8_t *bitmap, |
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int64_t sector_num, int nb_sectors, |
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int *num_same) |
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{
|
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int changed; |
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| 198 |
|
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if (!bitmap || nb_sectors == 0) {
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*num_same = nb_sectors; |
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return 0; |
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} |
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|
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changed = is_bit_set(bitmap, sector_num); |
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for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {
|
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| 206 |
if (is_bit_set(bitmap, sector_num + *num_same) != changed) |
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break; |
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| 208 |
} |
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| 209 |
|
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| 210 |
return changed; |
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} |
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| 212 |
|
|
| 213 |
/* commit COW file into the raw image */ |
|
| 214 |
int bdrv_commit(BlockDriverState *bs) |
|
| 215 |
{
|
|
| 216 |
int64_t i; |
|
| 217 |
uint8_t *cow_bitmap; |
|
| 218 |
|
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| 219 |
if (!bs->cow_bitmap) {
|
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| 220 |
fprintf(stderr, "Already committed to %s\n", bs->filename); |
|
| 221 |
return 0; |
|
| 222 |
} |
|
| 223 |
|
|
| 224 |
if (bs->read_only) {
|
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fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename); |
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| 226 |
return -1; |
|
| 227 |
} |
|
| 228 |
|
|
| 229 |
cow_bitmap = bs->cow_bitmap; |
|
| 230 |
for (i = 0; i < bs->total_sectors; i++) {
|
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| 231 |
if (is_bit_set(cow_bitmap, i)) {
|
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| 232 |
unsigned char sector[512]; |
|
| 233 |
if (bdrv_read(bs, i, sector, 1) != 0) {
|
|
| 234 |
fprintf(stderr, "Error reading sector %lli: aborting commit\n", |
|
| 235 |
(long long)i); |
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| 236 |
return -1; |
|
| 237 |
} |
|
| 238 |
|
|
| 239 |
/* Make bdrv_write write to real file for a moment. */ |
|
| 240 |
bs->cow_bitmap = NULL; |
|
| 241 |
if (bdrv_write(bs, i, sector, 1) != 0) {
|
|
| 242 |
fprintf(stderr, "Error writing sector %lli: aborting commit\n", |
|
| 243 |
(long long)i); |
|
| 244 |
bs->cow_bitmap = cow_bitmap; |
|
| 245 |
return -1; |
|
| 246 |
} |
|
| 247 |
bs->cow_bitmap = cow_bitmap; |
|
| 248 |
} |
|
| 249 |
} |
|
| 250 |
fprintf(stderr, "Committed snapshot to %s\n", bs->filename); |
|
| 251 |
return 0; |
|
| 252 |
} |
|
| 253 |
|
|
| 82 | 254 |
/* return -1 if error */ |
| 83 | 255 |
int bdrv_read(BlockDriverState *bs, int64_t sector_num, |
| 84 | 256 |
uint8_t *buf, int nb_sectors) |
| 85 | 257 |
{
|
| 86 |
int ret; |
|
| 258 |
int ret, n, fd; |
|
| 259 |
int64_t offset; |
|
| 260 |
|
|
| 261 |
while (nb_sectors > 0) {
|
|
| 262 |
if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {
|
|
| 263 |
fd = bs->cow_fd; |
|
| 264 |
offset = bs->cow_sectors_offset; |
|
| 265 |
} else {
|
|
| 266 |
fd = bs->fd; |
|
| 267 |
offset = 0; |
|
| 268 |
} |
|
| 87 | 269 |
|
| 88 |
lseek64(bs->fd, sector_num * 512, SEEK_SET); |
|
| 89 |
ret = read(bs->fd, buf, nb_sectors * 512); |
|
| 90 |
if (ret != nb_sectors * 512) |
|
| 91 |
return -1; |
|
| 92 |
else |
|
| 93 |
return 0; |
|
| 270 |
if (fd < 0) {
|
|
| 271 |
/* no file, just return empty sectors */ |
|
| 272 |
memset(buf, 0, n * 512); |
|
| 273 |
} else {
|
|
| 274 |
offset += sector_num * 512; |
|
| 275 |
lseek64(fd, offset, SEEK_SET); |
|
| 276 |
ret = read(fd, buf, n * 512); |
|
| 277 |
if (ret != n * 512) {
|
|
| 278 |
return -1; |
|
| 279 |
} |
|
| 280 |
} |
|
| 281 |
nb_sectors -= n; |
|
| 282 |
sector_num += n; |
|
| 283 |
buf += n * 512; |
|
| 284 |
} |
|
| 285 |
return 0; |
|
| 94 | 286 |
} |
| 95 | 287 |
|
| 96 | 288 |
/* return -1 if error */ |
| 97 | 289 |
int bdrv_write(BlockDriverState *bs, int64_t sector_num, |
| 98 | 290 |
const uint8_t *buf, int nb_sectors) |
| 99 | 291 |
{
|
| 100 |
int ret; |
|
| 292 |
int ret, fd, i; |
|
| 293 |
int64_t offset, retl; |
|
| 101 | 294 |
|
| 102 | 295 |
if (bs->read_only) |
| 103 | 296 |
return -1; |
| 104 | 297 |
|
| 105 |
lseek64(bs->fd, sector_num * 512, SEEK_SET); |
|
| 106 |
ret = write(bs->fd, buf, nb_sectors * 512); |
|
| 107 |
if (ret != nb_sectors * 512) |
|
| 298 |
if (bs->cow_bitmap) {
|
|
| 299 |
fd = bs->cow_fd; |
|
| 300 |
offset = bs->cow_sectors_offset; |
|
| 301 |
} else {
|
|
| 302 |
fd = bs->fd; |
|
| 303 |
offset = 0; |
|
| 304 |
} |
|
| 305 |
|
|
| 306 |
offset += sector_num * 512; |
|
| 307 |
retl = lseek64(fd, offset, SEEK_SET); |
|
| 308 |
if (retl == -1) {
|
|
| 108 | 309 |
return -1; |
| 109 |
else |
|
| 110 |
return 0; |
|
| 310 |
} |
|
| 311 |
ret = write(fd, buf, nb_sectors * 512); |
|
| 312 |
if (ret != nb_sectors * 512) {
|
|
| 313 |
return -1; |
|
| 314 |
} |
|
| 315 |
|
|
| 316 |
if (bs->cow_bitmap) {
|
|
| 317 |
for (i = 0; i < nb_sectors; i++) |
|
| 318 |
set_bit(bs->cow_bitmap, sector_num + i); |
|
| 319 |
} |
|
| 320 |
return 0; |
|
| 111 | 321 |
} |
| 112 | 322 |
|
| 113 | 323 |
void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr) |
Also available in: Unified diff