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4dc822d726
qcow2 writes a cluster reference count on every cluster update. This causes performance to crater when using anything but cache=writeback. This is most noticeable when using savevm. Right now, qcow2 isn't a reliable format regardless of the type of cache your using because metadata is not updated in the correct order. Considering this, I think it's somewhat reasonable to use writeback caching by default with qcow2 files. It at least avoids the massive performance regression for users until we sort out the issues in qcow2. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5879 c046a42c-6fe2-441c-8c8c-71466251a162
163 lines
6.8 KiB
C
163 lines
6.8 KiB
C
#ifndef BLOCK_H
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#define BLOCK_H
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#include "qemu-aio.h"
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/* block.c */
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typedef struct BlockDriver BlockDriver;
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extern BlockDriver bdrv_raw;
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extern BlockDriver bdrv_host_device;
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extern BlockDriver bdrv_cow;
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extern BlockDriver bdrv_qcow;
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extern BlockDriver bdrv_vmdk;
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extern BlockDriver bdrv_cloop;
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extern BlockDriver bdrv_dmg;
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extern BlockDriver bdrv_bochs;
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extern BlockDriver bdrv_vpc;
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extern BlockDriver bdrv_vvfat;
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extern BlockDriver bdrv_qcow2;
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extern BlockDriver bdrv_parallels;
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extern BlockDriver bdrv_nbd;
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typedef struct BlockDriverInfo {
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/* in bytes, 0 if irrelevant */
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int cluster_size;
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/* offset at which the VM state can be saved (0 if not possible) */
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int64_t vm_state_offset;
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} BlockDriverInfo;
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typedef struct QEMUSnapshotInfo {
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char id_str[128]; /* unique snapshot id */
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/* the following fields are informative. They are not needed for
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the consistency of the snapshot */
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char name[256]; /* user choosen name */
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uint32_t vm_state_size; /* VM state info size */
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uint32_t date_sec; /* UTC date of the snapshot */
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uint32_t date_nsec;
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uint64_t vm_clock_nsec; /* VM clock relative to boot */
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} QEMUSnapshotInfo;
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#define BDRV_O_RDONLY 0x0000
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#define BDRV_O_RDWR 0x0002
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#define BDRV_O_ACCESS 0x0003
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#define BDRV_O_CREAT 0x0004 /* create an empty file */
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#define BDRV_O_SNAPSHOT 0x0008 /* open the file read only and save writes in a snapshot */
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#define BDRV_O_FILE 0x0010 /* open as a raw file (do not try to
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use a disk image format on top of
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it (default for
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bdrv_file_open()) */
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#define BDRV_O_NOCACHE 0x0020 /* do not use the host page cache */
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#define BDRV_O_CACHE_WB 0x0040 /* use write-back caching */
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#define BDRV_O_CACHE_DEF 0x0080 /* use default caching */
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#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_CACHE_DEF)
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void bdrv_info(void);
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void bdrv_info_stats(void);
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void bdrv_init(void);
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BlockDriver *bdrv_find_format(const char *format_name);
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int bdrv_create(BlockDriver *drv,
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const char *filename, int64_t size_in_sectors,
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const char *backing_file, int flags);
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BlockDriverState *bdrv_new(const char *device_name);
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void bdrv_delete(BlockDriverState *bs);
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int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags);
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int bdrv_open(BlockDriverState *bs, const char *filename, int flags);
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int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
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BlockDriver *drv);
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void bdrv_close(BlockDriverState *bs);
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int bdrv_read(BlockDriverState *bs, int64_t sector_num,
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uint8_t *buf, int nb_sectors);
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int bdrv_write(BlockDriverState *bs, int64_t sector_num,
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const uint8_t *buf, int nb_sectors);
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int bdrv_pread(BlockDriverState *bs, int64_t offset,
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void *buf, int count);
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int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
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const void *buf, int count);
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int bdrv_truncate(BlockDriverState *bs, int64_t offset);
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int64_t bdrv_getlength(BlockDriverState *bs);
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void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
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void bdrv_guess_geometry(BlockDriverState *bs, int *pcyls, int *pheads, int *psecs);
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int bdrv_commit(BlockDriverState *bs);
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/* async block I/O */
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typedef struct BlockDriverAIOCB BlockDriverAIOCB;
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typedef void BlockDriverCompletionFunc(void *opaque, int ret);
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BlockDriverAIOCB *bdrv_aio_read(BlockDriverState *bs, int64_t sector_num,
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uint8_t *buf, int nb_sectors,
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BlockDriverCompletionFunc *cb, void *opaque);
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BlockDriverAIOCB *bdrv_aio_write(BlockDriverState *bs, int64_t sector_num,
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const uint8_t *buf, int nb_sectors,
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BlockDriverCompletionFunc *cb, void *opaque);
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void bdrv_aio_cancel(BlockDriverAIOCB *acb);
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int qemu_key_check(BlockDriverState *bs, const char *name);
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/* Ensure contents are flushed to disk. */
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void bdrv_flush(BlockDriverState *bs);
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void bdrv_flush_all(void);
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int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
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int *pnum);
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#define BDRV_TYPE_HD 0
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#define BDRV_TYPE_CDROM 1
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#define BDRV_TYPE_FLOPPY 2
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#define BIOS_ATA_TRANSLATION_AUTO 0
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#define BIOS_ATA_TRANSLATION_NONE 1
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#define BIOS_ATA_TRANSLATION_LBA 2
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#define BIOS_ATA_TRANSLATION_LARGE 3
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#define BIOS_ATA_TRANSLATION_RECHS 4
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void bdrv_set_geometry_hint(BlockDriverState *bs,
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int cyls, int heads, int secs);
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void bdrv_set_type_hint(BlockDriverState *bs, int type);
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void bdrv_set_translation_hint(BlockDriverState *bs, int translation);
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void bdrv_get_geometry_hint(BlockDriverState *bs,
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int *pcyls, int *pheads, int *psecs);
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int bdrv_get_type_hint(BlockDriverState *bs);
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int bdrv_get_translation_hint(BlockDriverState *bs);
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int bdrv_is_removable(BlockDriverState *bs);
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int bdrv_is_read_only(BlockDriverState *bs);
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int bdrv_is_sg(BlockDriverState *bs);
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int bdrv_is_inserted(BlockDriverState *bs);
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int bdrv_media_changed(BlockDriverState *bs);
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int bdrv_is_locked(BlockDriverState *bs);
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void bdrv_set_locked(BlockDriverState *bs, int locked);
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void bdrv_eject(BlockDriverState *bs, int eject_flag);
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void bdrv_set_change_cb(BlockDriverState *bs,
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void (*change_cb)(void *opaque), void *opaque);
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void bdrv_get_format(BlockDriverState *bs, char *buf, int buf_size);
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BlockDriverState *bdrv_find(const char *name);
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void bdrv_iterate(void (*it)(void *opaque, const char *name), void *opaque);
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int bdrv_is_encrypted(BlockDriverState *bs);
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int bdrv_set_key(BlockDriverState *bs, const char *key);
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void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
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void *opaque);
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const char *bdrv_get_device_name(BlockDriverState *bs);
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int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
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const uint8_t *buf, int nb_sectors);
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int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
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void bdrv_get_backing_filename(BlockDriverState *bs,
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char *filename, int filename_size);
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int bdrv_snapshot_create(BlockDriverState *bs,
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QEMUSnapshotInfo *sn_info);
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int bdrv_snapshot_goto(BlockDriverState *bs,
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const char *snapshot_id);
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int bdrv_snapshot_delete(BlockDriverState *bs, const char *snapshot_id);
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int bdrv_snapshot_list(BlockDriverState *bs,
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QEMUSnapshotInfo **psn_info);
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char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn);
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int bdrv_ioctl(BlockDriverState *bs, unsigned long int req, void *buf);
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char *get_human_readable_size(char *buf, int buf_size, int64_t size);
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int path_is_absolute(const char *path);
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void path_combine(char *dest, int dest_size,
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const char *base_path,
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const char *filename);
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#endif
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