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Refactor QEMUFile for live migration 

To support live migration, we override QEMUFile so that instead of writing to
disk, the save/restore state happens over a network connection.

This patch makes QEMUFile read/write operations function pointers so that we
can override them for live migration.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5352 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2008-09-29 16:25:16 +00:00
parent f504975609
commit 5dafc53f1f
2 changed files with 237 additions and 56 deletions
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35
hw/hw.h
View File

@ -7,9 +7,36 @@
/* VM Load/Save */
/* This function writes a chunk of data to a file at the given position.
* The pos argument can be ignored if the file is only being used for
* streaming. The handler should try to write all of the data it can.
*/
typedef void (QEMUFilePutBufferFunc)(void *opaque, const uint8_t *buf,
int64_t pos, int size);
/* Read a chunk of data from a file at the given position. The pos argument
* can be ignored if the file is only be used for streaming. The number of
* bytes actually read should be returned.
*/
typedef int (QEMUFileGetBufferFunc)(void *opaque, uint8_t *buf,
int64_t pos, int size);
/* Close a file and return an error code */
typedef int (QEMUFileCloseFunc)(void *opaque);
/* Called to determine if the file has exceeded it's bandwidth allocation. The
* bandwidth capping is a soft limit, not a hard limit.
*/
typedef int (QEMUFileRateLimit)(void *opaque);
QEMUFile *qemu_fopen_ops(void *opaque, QEMUFilePutBufferFunc *put_buffer,
QEMUFileGetBufferFunc *get_buffer,
QEMUFileCloseFunc *close,
QEMUFileRateLimit *rate_limit);
QEMUFile *qemu_fopen(const char *filename, const char *mode);
QEMUFile *qemu_fopen_fd(int fd);
void qemu_fflush(QEMUFile *f);
void qemu_fclose(QEMUFile *f);
int qemu_fclose(QEMUFile *f);
void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size);
void qemu_put_byte(QEMUFile *f, int v);
void qemu_put_be16(QEMUFile *f, unsigned int v);
@ -20,6 +47,12 @@ int qemu_get_byte(QEMUFile *f);
unsigned int qemu_get_be16(QEMUFile *f);
unsigned int qemu_get_be32(QEMUFile *f);
uint64_t qemu_get_be64(QEMUFile *f);
int qemu_file_rate_limit(QEMUFile *f);
/* Try to send any outstanding data. This function is useful when output is
* halted due to rate limiting or EAGAIN errors occur as it can be used to
* resume output. */
void qemu_file_put_notify(QEMUFile *f);
static inline void qemu_put_be64s(QEMUFile *f, const uint64_t *pv)
{

258
vl.c
View File

@ -6198,11 +6198,12 @@ void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
#define IO_BUF_SIZE 32768
struct QEMUFile {
FILE *outfile;
BlockDriverState *bs;
int is_file;
int is_writable;
int64_t base_offset;
QEMUFilePutBufferFunc *put_buffer;
QEMUFileGetBufferFunc *get_buffer;
QEMUFileCloseFunc *close;
QEMUFileRateLimit *rate_limit;
void *opaque;
int64_t buf_offset; /* start of buffer when writing, end of buffer
when reading */
int buf_index;
@ -6210,58 +6211,198 @@ struct QEMUFile {
uint8_t buf[IO_BUF_SIZE];
};
typedef struct QEMUFileFD
{
int fd;
QEMUFile *file;
} QEMUFileFD;
static void fd_put_notify(void *opaque)
{
QEMUFileFD *s = opaque;
/* Remove writable callback and do a put notify */
qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
qemu_file_put_notify(s->file);
}
static int fd_put_buffer(void *opaque, const uint8_t *buf,
int64_t pos, int size)
{
QEMUFileFD *s = opaque;
ssize_t len;
do {
len = write(s->fd, buf, size);
} while (len == -1 && errno == EINTR);
if (len == -1)
len = -errno;
/* When the fd becomes writable again, register a callback to do
* a put notify */
if (len == -EAGAIN)
qemu_set_fd_handler2(s->fd, NULL, NULL, fd_put_notify, s);
return len;
}
static int fd_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
QEMUFileFD *s = opaque;
ssize_t len;
do {
len = read(s->fd, buf, size);
} while (len == -1 && errno == EINTR);
if (len == -1)
len = -errno;
return len;
}
static int fd_close(void *opaque)
{
QEMUFileFD *s = opaque;
qemu_free(s);
return 0;
}
QEMUFile *qemu_fopen_fd(int fd)
{
QEMUFileFD *s = qemu_mallocz(sizeof(QEMUFileFD));
if (s == NULL)
return NULL;
s->fd = fd;
s->file = qemu_fopen_ops(s, fd_put_buffer, fd_get_buffer, fd_close, NULL);
return s->file;
}
typedef struct QEMUFileStdio
{
FILE *outfile;
} QEMUFileStdio;
static void file_put_buffer(void *opaque, const uint8_t *buf,
int64_t pos, int size)
{
QEMUFileStdio *s = opaque;
fseek(s->outfile, pos, SEEK_SET);
fwrite(buf, 1, size, s->outfile);
}
static int file_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
QEMUFileStdio *s = opaque;
fseek(s->outfile, pos, SEEK_SET);
return fread(buf, 1, size, s->outfile);
}
static int file_close(void *opaque)
{
QEMUFileStdio *s = opaque;
fclose(s->outfile);
qemu_free(s);
return 0;
}
QEMUFile *qemu_fopen(const char *filename, const char *mode)
{
QEMUFile *f;
QEMUFileStdio *s;
f = qemu_mallocz(sizeof(QEMUFile));
if (!f)
s = qemu_mallocz(sizeof(QEMUFileStdio));
if (!s)
return NULL;
if (!strcmp(mode, "wb")) {
f->is_writable = 1;
} else if (!strcmp(mode, "rb")) {
f->is_writable = 0;
} else {
s->outfile = fopen(filename, mode);
if (!s->outfile)
goto fail;
}
f->outfile = fopen(filename, mode);
if (!f->outfile)
goto fail;
f->is_file = 1;
return f;
fail:
if (f->outfile)
fclose(f->outfile);
qemu_free(f);
if (!strcmp(mode, "wb"))
return qemu_fopen_ops(s, file_put_buffer, NULL, file_close, NULL);
else if (!strcmp(mode, "rb"))
return qemu_fopen_ops(s, NULL, file_get_buffer, file_close, NULL);
fail:
if (s->outfile)
fclose(s->outfile);
qemu_free(s);
return NULL;
}
static QEMUFile *qemu_fopen_bdrv(BlockDriverState *bs, int64_t offset, int is_writable)
typedef struct QEMUFileBdrv
{
BlockDriverState *bs;
int64_t base_offset;
} QEMUFileBdrv;
static void bdrv_put_buffer(void *opaque, const uint8_t *buf,
int64_t pos, int size)
{
QEMUFileBdrv *s = opaque;
bdrv_pwrite(s->bs, s->base_offset + pos, buf, size);
}
static int bdrv_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
QEMUFileBdrv *s = opaque;
return bdrv_pread(s->bs, s->base_offset + pos, buf, size);
}
static int bdrv_fclose(void *opaque)
{
QEMUFileBdrv *s = opaque;
qemu_free(s);
return 0;
}
QEMUFile *qemu_fopen_bdrv(BlockDriverState *bs, int64_t offset, int is_writable)
{
QEMUFileBdrv *s;
s = qemu_mallocz(sizeof(QEMUFileBdrv));
if (!s)
return NULL;
s->bs = bs;
s->base_offset = offset;
if (is_writable)
return qemu_fopen_ops(s, bdrv_put_buffer, NULL, bdrv_fclose, NULL);
return qemu_fopen_ops(s, NULL, bdrv_get_buffer, bdrv_fclose, NULL);
}
QEMUFile *qemu_fopen_ops(void *opaque, QEMUFilePutBufferFunc *put_buffer,
QEMUFileGetBufferFunc *get_buffer,
QEMUFileCloseFunc *close,
QEMUFileRateLimit *rate_limit)
{
QEMUFile *f;
f = qemu_mallocz(sizeof(QEMUFile));
if (!f)
return NULL;
f->is_file = 0;
f->bs = bs;
f->is_writable = is_writable;
f->base_offset = offset;
f->opaque = opaque;
f->put_buffer = put_buffer;
f->get_buffer = get_buffer;
f->close = close;
f->rate_limit = rate_limit;
return f;
}
void qemu_fflush(QEMUFile *f)
{
if (!f->is_writable)
if (!f->put_buffer)
return;
if (f->buf_index > 0) {
if (f->is_file) {
fseek(f->outfile, f->buf_offset, SEEK_SET);
fwrite(f->buf, 1, f->buf_index, f->outfile);
} else {
bdrv_pwrite(f->bs, f->base_offset + f->buf_offset,
f->buf, f->buf_index);
}
f->put_buffer(f->opaque, f->buf, f->buf_offset, f->buf_index);
f->buf_offset += f->buf_index;
f->buf_index = 0;
}
@ -6271,32 +6412,31 @@ static void qemu_fill_buffer(QEMUFile *f)
{
int len;
if (f->is_writable)
if (!f->get_buffer)
return;
if (f->is_file) {
fseek(f->outfile, f->buf_offset, SEEK_SET);
len = fread(f->buf, 1, IO_BUF_SIZE, f->outfile);
if (len < 0)
len = 0;
} else {
len = bdrv_pread(f->bs, f->base_offset + f->buf_offset,
f->buf, IO_BUF_SIZE);
if (len < 0)
len = 0;
}
len = f->get_buffer(f->opaque, f->buf, f->buf_offset, IO_BUF_SIZE);
if (len < 0)
len = 0;
f->buf_index = 0;
f->buf_size = len;
f->buf_offset += len;
}
void qemu_fclose(QEMUFile *f)
int qemu_fclose(QEMUFile *f)
{
if (f->is_writable)
qemu_fflush(f);
if (f->is_file) {
fclose(f->outfile);
}
int ret = 0;
qemu_fflush(f);
if (f->close)
ret = f->close(f->opaque);
qemu_free(f);
return ret;
}
void qemu_file_put_notify(QEMUFile *f)
{
f->put_buffer(f->opaque, NULL, 0, 0);
}
void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
@ -6370,7 +6510,7 @@ int64_t qemu_fseek(QEMUFile *f, int64_t pos, int whence)
/* SEEK_END not supported */
return -1;
}
if (f->is_writable) {
if (f->put_buffer) {
qemu_fflush(f);
f->buf_offset = pos;
} else {
@ -6381,6 +6521,14 @@ int64_t qemu_fseek(QEMUFile *f, int64_t pos, int whence)
return pos;
}
int qemu_file_rate_limit(QEMUFile *f)
{
if (f->rate_limit)
return f->rate_limit(f->opaque);
return 0;
}
void qemu_put_be16(QEMUFile *f, unsigned int v)
{
qemu_put_byte(f, v >> 8);