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qemu-patch-raspberry4/block.h
Miguel Di Ciurcio Filho feeee5aca7 savevm: Really verify if a drive supports snapshots 
Both bdrv_can_snapshot() and bdrv_has_snapshot() does not work as advertized.

First issue: Their names implies different porpouses, but they do the same thing
and have exactly the same code. Maybe copied and pasted and forgotten?
bdrv_has_snapshot() is called in various places for actually checking if there
is snapshots or not.

Second issue: the way bdrv_can_snapshot() verifies if a block driver supports or
not snapshots does not catch all cases. E.g.: a raw image.

So when do_savevm() is called, first thing it does is to set a global
BlockDriverState to save the VM memory state calling get_bs_snapshots().

static BlockDriverState *get_bs_snapshots(void)
{
    BlockDriverState *bs;
    DriveInfo *dinfo;

    if (bs_snapshots)
        return bs_snapshots;
    QTAILQ_FOREACH(dinfo, &drives, next) {
        bs = dinfo->bdrv;
        if (bdrv_can_snapshot(bs))
            goto ok;
    }
    return NULL;
 ok:
    bs_snapshots = bs;
    return bs;
}

bdrv_can_snapshot() may return a BlockDriverState that does not support
snapshots and do_savevm() goes on.

Later on in do_savevm(), we find:

    QTAILQ_FOREACH(dinfo, &drives, next) {
        bs1 = dinfo->bdrv;
        if (bdrv_has_snapshot(bs1)) {
            /* Write VM state size only to the image that contains the state */
            sn->vm_state_size = (bs == bs1 ? vm_state_size : 0);
            ret = bdrv_snapshot_create(bs1, sn);
            if (ret < 0) {
                monitor_printf(mon, "Error while creating snapshot on '%s'\n",
                               bdrv_get_device_name(bs1));
            }
        }
    }

bdrv_has_snapshot(bs1) is not checking if the device does support or has
snapshots as explained above. Only in bdrv_snapshot_create() the device is
actually checked for snapshot support.

So, in cases where the first device supports snapshots, and the second does not,
the snapshot on the first will happen anyways. I believe this is not a good
behavior. It should be an all or nothing process.

This patch addresses these issues by making bdrv_can_snapshot() actually do
what it must do and enforces better tests to avoid errors in the middle of
do_savevm(). bdrv_has_snapshot() is removed and replaced by bdrv_can_snapshot()
where appropriate.

bdrv_can_snapshot() was moved from savevm.c to block.c. It makes more sense to me.

The loadvm_state() function was updated too to enforce that when loading a VM at
least all writable devices must support snapshots too.

Signed-off-by: Miguel Di Ciurcio Filho <miguel.filho@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-15 09:41:58 +02:00

261 lines
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#ifndef BLOCK_H
#define BLOCK_H
#include "qemu-aio.h"
#include "qemu-common.h"
#include "qemu-option.h"
#include "qobject.h"
/* block.c */
typedef struct BlockDriver BlockDriver;
typedef struct BlockDriverInfo {
/* in bytes, 0 if irrelevant */
int cluster_size;
/* offset at which the VM state can be saved (0 if not possible) */
int64_t vm_state_offset;
} BlockDriverInfo;
typedef struct QEMUSnapshotInfo {
char id_str[128]; /* unique snapshot id */
/* the following fields are informative. They are not needed for
the consistency of the snapshot */
char name[256]; /* user choosen name */
uint32_t vm_state_size; /* VM state info size */
uint32_t date_sec; /* UTC date of the snapshot */
uint32_t date_nsec;
uint64_t vm_clock_nsec; /* VM clock relative to boot */
} QEMUSnapshotInfo;
#define BDRV_O_RDWR 0x0002
#define BDRV_O_SNAPSHOT 0x0008 /* open the file read only and save writes in a snapshot */
#define BDRV_O_NOCACHE 0x0020 /* do not use the host page cache */
#define BDRV_O_CACHE_WB 0x0040 /* use write-back caching */
#define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool */
#define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
#define BDRV_O_NO_FLUSH 0x0200 /* disable flushing on this disk */
#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB)
#define BDRV_SECTOR_BITS 9
#define BDRV_SECTOR_SIZE (1ULL << BDRV_SECTOR_BITS)
#define BDRV_SECTOR_MASK ~(BDRV_SECTOR_SIZE - 1)
typedef enum {
BDRV_ACTION_REPORT, BDRV_ACTION_IGNORE, BDRV_ACTION_STOP
} BlockMonEventAction;
void bdrv_mon_event(const BlockDriverState *bdrv,
BlockMonEventAction action, int is_read);
void bdrv_info_print(Monitor *mon, const QObject *data);
void bdrv_info(Monitor *mon, QObject **ret_data);
void bdrv_stats_print(Monitor *mon, const QObject *data);
void bdrv_info_stats(Monitor *mon, QObject **ret_data);
void bdrv_init(void);
void bdrv_init_with_whitelist(void);
BlockDriver *bdrv_find_protocol(const char *filename);
BlockDriver *bdrv_find_format(const char *format_name);
BlockDriver *bdrv_find_whitelisted_format(const char *format_name);
int bdrv_create(BlockDriver *drv, const char* filename,
QEMUOptionParameter *options);
int bdrv_create_file(const char* filename, QEMUOptionParameter *options);
BlockDriverState *bdrv_new(const char *device_name);
void bdrv_delete(BlockDriverState *bs);
int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags);
int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
BlockDriver *drv);
void bdrv_close(BlockDriverState *bs);
int bdrv_check(BlockDriverState *bs);
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors);
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors);
int bdrv_pread(BlockDriverState *bs, int64_t offset,
void *buf, int count);
int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
const void *buf, int count);
int bdrv_truncate(BlockDriverState *bs, int64_t offset);
int64_t bdrv_getlength(BlockDriverState *bs);
void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
void bdrv_guess_geometry(BlockDriverState *bs, int *pcyls, int *pheads, int *psecs);
int bdrv_commit(BlockDriverState *bs);
int bdrv_change_backing_file(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt);
void bdrv_register(BlockDriver *bdrv);
/* async block I/O */
typedef struct BlockDriverAIOCB BlockDriverAIOCB;
typedef void BlockDriverCompletionFunc(void *opaque, int ret);
typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
int sector_num);
BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *iov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *iov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
void bdrv_aio_cancel(BlockDriverAIOCB *acb);
typedef struct BlockRequest {
/* Fields to be filled by multiwrite caller */
int64_t sector;
int nb_sectors;
QEMUIOVector *qiov;
BlockDriverCompletionFunc *cb;
void *opaque;
/* Filled by multiwrite implementation */
int error;
} BlockRequest;
int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs,
int num_reqs);
/* sg packet commands */
int bdrv_ioctl(BlockDriverState *bs, unsigned long int req, void *buf);
BlockDriverAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
unsigned long int req, void *buf,
BlockDriverCompletionFunc *cb, void *opaque);
/* Ensure contents are flushed to disk. */
void bdrv_flush(BlockDriverState *bs);
void bdrv_flush_all(void);
void bdrv_close_all(void);
int bdrv_has_zero_init(BlockDriverState *bs);
int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
int *pnum);
#define BDRV_TYPE_HD 0
#define BDRV_TYPE_CDROM 1
#define BDRV_TYPE_FLOPPY 2
#define BIOS_ATA_TRANSLATION_AUTO 0
#define BIOS_ATA_TRANSLATION_NONE 1
#define BIOS_ATA_TRANSLATION_LBA 2
#define BIOS_ATA_TRANSLATION_LARGE 3
#define BIOS_ATA_TRANSLATION_RECHS 4
void bdrv_set_geometry_hint(BlockDriverState *bs,
int cyls, int heads, int secs);
void bdrv_set_type_hint(BlockDriverState *bs, int type);
void bdrv_set_translation_hint(BlockDriverState *bs, int translation);
void bdrv_get_geometry_hint(BlockDriverState *bs,
int *pcyls, int *pheads, int *psecs);
int bdrv_get_type_hint(BlockDriverState *bs);
int bdrv_get_translation_hint(BlockDriverState *bs);
int bdrv_is_removable(BlockDriverState *bs);
int bdrv_is_read_only(BlockDriverState *bs);
int bdrv_is_sg(BlockDriverState *bs);
int bdrv_enable_write_cache(BlockDriverState *bs);
int bdrv_is_inserted(BlockDriverState *bs);
int bdrv_media_changed(BlockDriverState *bs);
int bdrv_is_locked(BlockDriverState *bs);
void bdrv_set_locked(BlockDriverState *bs, int locked);
int bdrv_eject(BlockDriverState *bs, int eject_flag);
void bdrv_set_change_cb(BlockDriverState *bs,
void (*change_cb)(void *opaque), void *opaque);
void bdrv_get_format(BlockDriverState *bs, char *buf, int buf_size);
BlockDriverState *bdrv_find(const char *name);
void bdrv_iterate(void (*it)(void *opaque, BlockDriverState *bs),
void *opaque);
int bdrv_is_encrypted(BlockDriverState *bs);
int bdrv_key_required(BlockDriverState *bs);
int bdrv_set_key(BlockDriverState *bs, const char *key);
int bdrv_query_missing_keys(void);
void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
void *opaque);
const char *bdrv_get_device_name(BlockDriverState *bs);
int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors);
int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
const char *bdrv_get_encrypted_filename(BlockDriverState *bs);
void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size);
int bdrv_can_snapshot(BlockDriverState *bs);
int bdrv_snapshot_create(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info);
int bdrv_snapshot_goto(BlockDriverState *bs,
const char *snapshot_id);
int bdrv_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
int bdrv_snapshot_list(BlockDriverState *bs,
QEMUSnapshotInfo **psn_info);
char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn);
char *get_human_readable_size(char *buf, int buf_size, int64_t size);
int path_is_absolute(const char *path);
void path_combine(char *dest, int dest_size,
const char *base_path,
const char *filename);
int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
int64_t pos, int size);
int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
int64_t pos, int size);
#define BDRV_SECTORS_PER_DIRTY_CHUNK 2048
void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable);
int bdrv_get_dirty(BlockDriverState *bs, int64_t sector);
void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors);
int64_t bdrv_get_dirty_count(BlockDriverState *bs);
typedef enum {
BLKDBG_L1_UPDATE,
BLKDBG_L1_GROW_ALLOC_TABLE,
BLKDBG_L1_GROW_WRITE_TABLE,
BLKDBG_L1_GROW_ACTIVATE_TABLE,
BLKDBG_L2_LOAD,
BLKDBG_L2_UPDATE,
BLKDBG_L2_UPDATE_COMPRESSED,
BLKDBG_L2_ALLOC_COW_READ,
BLKDBG_L2_ALLOC_WRITE,
BLKDBG_READ,
BLKDBG_READ_AIO,
BLKDBG_READ_BACKING,
BLKDBG_READ_BACKING_AIO,
BLKDBG_READ_COMPRESSED,
BLKDBG_WRITE_AIO,
BLKDBG_WRITE_COMPRESSED,
BLKDBG_VMSTATE_LOAD,
BLKDBG_VMSTATE_SAVE,
BLKDBG_COW_READ,
BLKDBG_COW_WRITE,
BLKDBG_REFTABLE_LOAD,
BLKDBG_REFTABLE_GROW,
BLKDBG_REFBLOCK_LOAD,
BLKDBG_REFBLOCK_UPDATE,
BLKDBG_REFBLOCK_UPDATE_PART,
BLKDBG_REFBLOCK_ALLOC,
BLKDBG_REFBLOCK_ALLOC_HOOKUP,
BLKDBG_REFBLOCK_ALLOC_WRITE,
BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS,
BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE,
BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE,
BLKDBG_CLUSTER_ALLOC,
BLKDBG_CLUSTER_ALLOC_BYTES,
BLKDBG_CLUSTER_FREE,
BLKDBG_EVENT_MAX,
} BlkDebugEvent;
#define BLKDBG_EVENT(bs, evt) bdrv_debug_event(bs, evt)
void bdrv_debug_event(BlockDriverState *bs, BlkDebugEvent event);
#endif
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