mirror of
https://github.com/Motorhead1991/qemu.git
synced 2025-08-02 07:13:54 -06:00
added user mode Linux Copy On Write disk image support - added -snapshot support (initial patch by Rusty Russell)
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@309 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
bellard
parent
cd4c3e888a
commit
33e3963e1b
5 changed files with 442 additions and 44 deletions
260
block.c
260
block.c
|
|
@ -38,76 +38,286 @@
|
|||
#include <sys/poll.h>
|
||||
#include <errno.h>
|
||||
#include <sys/wait.h>
|
||||
#include <netinet/in.h>
|
||||
|
||||
#include "vl.h"
|
||||
|
||||
#define NO_THUNK_TYPE_SIZE
|
||||
#include "thunk.h"
|
||||
|
||||
struct BlockDriverState {
|
||||
int fd;
|
||||
int fd; /* if -1, only COW mappings */
|
||||
int64_t total_sectors;
|
||||
int read_only;
|
||||
|
||||
uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */
|
||||
uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */
|
||||
int cow_bitmap_size;
|
||||
int cow_fd;
|
||||
int64_t cow_sectors_offset;
|
||||
char filename[1024];
|
||||
};
|
||||
|
||||
BlockDriverState *bdrv_open(const char *filename)
|
||||
BlockDriverState *bdrv_open(const char *filename, int snapshot)
|
||||
{
|
||||
BlockDriverState *bs;
|
||||
int fd;
|
||||
int fd, cow_fd;
|
||||
int64_t size;
|
||||
char template[] = "/tmp/vl.XXXXXX";
|
||||
struct cow_header_v2 cow_header;
|
||||
struct stat st;
|
||||
|
||||
bs = malloc(sizeof(BlockDriverState));
|
||||
if(!bs)
|
||||
return NULL;
|
||||
bs->read_only = 0;
|
||||
fd = open(filename, O_RDWR);
|
||||
bs->fd = -1;
|
||||
bs->cow_fd = -1;
|
||||
bs->cow_bitmap = NULL;
|
||||
strcpy(bs->filename, filename);
|
||||
|
||||
/* open standard HD image */
|
||||
fd = open(filename, O_RDWR | O_LARGEFILE);
|
||||
if (fd < 0) {
|
||||
fd = open(filename, O_RDONLY);
|
||||
/* read only image on disk */
|
||||
fd = open(filename, O_RDONLY | O_LARGEFILE);
|
||||
if (fd < 0) {
|
||||
close(fd);
|
||||
free(bs);
|
||||
return NULL;
|
||||
perror(filename);
|
||||
goto fail;
|
||||
}
|
||||
bs->read_only = 1;
|
||||
if (!snapshot)
|
||||
bs->read_only = 1;
|
||||
}
|
||||
size = lseek64(fd, 0, SEEK_END);
|
||||
bs->total_sectors = size / 512;
|
||||
bs->fd = fd;
|
||||
|
||||
/* see if it is a cow image */
|
||||
if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
|
||||
fprintf(stderr, "%s: could not read header\n", filename);
|
||||
goto fail;
|
||||
}
|
||||
if (cow_header.magic == htonl(COW_MAGIC) &&
|
||||
cow_header.version == htonl(COW_VERSION)) {
|
||||
/* cow image found */
|
||||
size = cow_header.size;
|
||||
#ifndef WORDS_BIGENDIAN
|
||||
size = bswap64(size);
|
||||
#endif
|
||||
bs->total_sectors = size / 512;
|
||||
|
||||
bs->cow_fd = fd;
|
||||
bs->fd = -1;
|
||||
if (cow_header.backing_file[0] != '\0') {
|
||||
if (stat(cow_header.backing_file, &st) != 0) {
|
||||
fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file);
|
||||
goto fail;
|
||||
}
|
||||
if (st.st_mtime != htonl(cow_header.mtime)) {
|
||||
fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file);
|
||||
goto fail;
|
||||
}
|
||||
fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE);
|
||||
if (fd < 0)
|
||||
goto fail;
|
||||
bs->fd = fd;
|
||||
}
|
||||
/* mmap the bitmap */
|
||||
bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header);
|
||||
bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size),
|
||||
bs->cow_bitmap_size,
|
||||
PROT_READ | PROT_WRITE,
|
||||
MAP_SHARED, bs->cow_fd, 0);
|
||||
if (bs->cow_bitmap_addr == MAP_FAILED)
|
||||
goto fail;
|
||||
bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header);
|
||||
bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511;
|
||||
snapshot = 0;
|
||||
} else {
|
||||
/* standard raw image */
|
||||
size = lseek64(fd, 0, SEEK_END);
|
||||
bs->total_sectors = size / 512;
|
||||
bs->fd = fd;
|
||||
}
|
||||
|
||||
if (snapshot) {
|
||||
/* create a temporary COW file */
|
||||
cow_fd = mkstemp(template);
|
||||
if (cow_fd < 0)
|
||||
goto fail;
|
||||
bs->cow_fd = cow_fd;
|
||||
unlink(template);
|
||||
|
||||
/* just need to allocate bitmap */
|
||||
bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3;
|
||||
bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size),
|
||||
bs->cow_bitmap_size,
|
||||
PROT_READ | PROT_WRITE,
|
||||
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
||||
if (bs->cow_bitmap_addr == MAP_FAILED)
|
||||
goto fail;
|
||||
bs->cow_bitmap = bs->cow_bitmap_addr;
|
||||
bs->cow_sectors_offset = 0;
|
||||
}
|
||||
|
||||
return bs;
|
||||
fail:
|
||||
bdrv_close(bs);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
void bdrv_close(BlockDriverState *bs)
|
||||
{
|
||||
close(bs->fd);
|
||||
/* we unmap the mapping so that it is written to the COW file */
|
||||
if (bs->cow_bitmap_addr)
|
||||
munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size);
|
||||
if (bs->cow_fd >= 0)
|
||||
close(bs->cow_fd);
|
||||
if (bs->fd >= 0)
|
||||
close(bs->fd);
|
||||
free(bs);
|
||||
}
|
||||
|
||||
static inline void set_bit(uint8_t *bitmap, int64_t bitnum)
|
||||
{
|
||||
bitmap[bitnum / 8] |= (1 << (bitnum%8));
|
||||
}
|
||||
|
||||
static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum)
|
||||
{
|
||||
return !!(bitmap[bitnum / 8] & (1 << (bitnum%8)));
|
||||
}
|
||||
|
||||
|
||||
/* Return true if first block has been changed (ie. current version is
|
||||
* in COW file). Set the number of continuous blocks for which that
|
||||
* is true. */
|
||||
static int is_changed(uint8_t *bitmap,
|
||||
int64_t sector_num, int nb_sectors,
|
||||
int *num_same)
|
||||
{
|
||||
int changed;
|
||||
|
||||
if (!bitmap || nb_sectors == 0) {
|
||||
*num_same = nb_sectors;
|
||||
return 0;
|
||||
}
|
||||
|
||||
changed = is_bit_set(bitmap, sector_num);
|
||||
for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {
|
||||
if (is_bit_set(bitmap, sector_num + *num_same) != changed)
|
||||
break;
|
||||
}
|
||||
|
||||
return changed;
|
||||
}
|
||||
|
||||
/* commit COW file into the raw image */
|
||||
int bdrv_commit(BlockDriverState *bs)
|
||||
{
|
||||
int64_t i;
|
||||
uint8_t *cow_bitmap;
|
||||
|
||||
if (!bs->cow_bitmap) {
|
||||
fprintf(stderr, "Already committed to %s\n", bs->filename);
|
||||
return 0;
|
||||
}
|
||||
|
||||
if (bs->read_only) {
|
||||
fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename);
|
||||
return -1;
|
||||
}
|
||||
|
||||
cow_bitmap = bs->cow_bitmap;
|
||||
for (i = 0; i < bs->total_sectors; i++) {
|
||||
if (is_bit_set(cow_bitmap, i)) {
|
||||
unsigned char sector[512];
|
||||
if (bdrv_read(bs, i, sector, 1) != 0) {
|
||||
fprintf(stderr, "Error reading sector %lli: aborting commit\n",
|
||||
(long long)i);
|
||||
return -1;
|
||||
}
|
||||
|
||||
/* Make bdrv_write write to real file for a moment. */
|
||||
bs->cow_bitmap = NULL;
|
||||
if (bdrv_write(bs, i, sector, 1) != 0) {
|
||||
fprintf(stderr, "Error writing sector %lli: aborting commit\n",
|
||||
(long long)i);
|
||||
bs->cow_bitmap = cow_bitmap;
|
||||
return -1;
|
||||
}
|
||||
bs->cow_bitmap = cow_bitmap;
|
||||
}
|
||||
}
|
||||
fprintf(stderr, "Committed snapshot to %s\n", bs->filename);
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* return -1 if error */
|
||||
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
|
||||
uint8_t *buf, int nb_sectors)
|
||||
{
|
||||
int ret;
|
||||
int ret, n, fd;
|
||||
int64_t offset;
|
||||
|
||||
while (nb_sectors > 0) {
|
||||
if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {
|
||||
fd = bs->cow_fd;
|
||||
offset = bs->cow_sectors_offset;
|
||||
} else {
|
||||
fd = bs->fd;
|
||||
offset = 0;
|
||||
}
|
||||
|
||||
lseek64(bs->fd, sector_num * 512, SEEK_SET);
|
||||
ret = read(bs->fd, buf, nb_sectors * 512);
|
||||
if (ret != nb_sectors * 512)
|
||||
return -1;
|
||||
else
|
||||
return 0;
|
||||
if (fd < 0) {
|
||||
/* no file, just return empty sectors */
|
||||
memset(buf, 0, n * 512);
|
||||
} else {
|
||||
offset += sector_num * 512;
|
||||
lseek64(fd, offset, SEEK_SET);
|
||||
ret = read(fd, buf, n * 512);
|
||||
if (ret != n * 512) {
|
||||
return -1;
|
||||
}
|
||||
}
|
||||
nb_sectors -= n;
|
||||
sector_num += n;
|
||||
buf += n * 512;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* return -1 if error */
|
||||
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
|
||||
const uint8_t *buf, int nb_sectors)
|
||||
{
|
||||
int ret;
|
||||
int ret, fd, i;
|
||||
int64_t offset, retl;
|
||||
|
||||
if (bs->read_only)
|
||||
return -1;
|
||||
|
||||
lseek64(bs->fd, sector_num * 512, SEEK_SET);
|
||||
ret = write(bs->fd, buf, nb_sectors * 512);
|
||||
if (ret != nb_sectors * 512)
|
||||
if (bs->cow_bitmap) {
|
||||
fd = bs->cow_fd;
|
||||
offset = bs->cow_sectors_offset;
|
||||
} else {
|
||||
fd = bs->fd;
|
||||
offset = 0;
|
||||
}
|
||||
|
||||
offset += sector_num * 512;
|
||||
retl = lseek64(fd, offset, SEEK_SET);
|
||||
if (retl == -1) {
|
||||
return -1;
|
||||
else
|
||||
return 0;
|
||||
}
|
||||
ret = write(fd, buf, nb_sectors * 512);
|
||||
if (ret != nb_sectors * 512) {
|
||||
return -1;
|
||||
}
|
||||
|
||||
if (bs->cow_bitmap) {
|
||||
for (i = 0; i < nb_sectors; i++)
|
||||
set_bit(bs->cow_bitmap, sector_num + i);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue