qemu-e2k/block/qcow2.h

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/*
* Block driver for the QCOW version 2 format
*
* Copyright (c) 2004-2006 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef BLOCK_QCOW2_H
#define BLOCK_QCOW2_H
#include "crypto/block.h"
#include "qemu/coroutine.h"
#include "qemu/units.h"
//#define DEBUG_ALLOC
//#define DEBUG_ALLOC2
//#define DEBUG_EXT
#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
#define QCOW_CRYPT_NONE 0
#define QCOW_CRYPT_AES 1
qcow2: add support for LUKS encryption format This adds support for using LUKS as an encryption format with the qcow2 file, using the new encrypt.format parameter to request "luks" format. e.g. # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encrypt.format=luks,encrypt.key-secret=sec0 \ test.qcow2 10G The legacy "encryption=on" parameter still results in creation of the old qcow2 AES format (and is equivalent to the new 'encryption-format=aes'). e.g. the following are equivalent: # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption=on,encrypt.key-secret=sec0 \ test.qcow2 10G # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption-format=aes,encrypt.key-secret=sec0 \ test.qcow2 10G With the LUKS format it is necessary to store the LUKS partition header and key material in the QCow2 file. This data can be many MB in size, so cannot go into the QCow2 header region directly. Thus the spec defines a FDE (Full Disk Encryption) header extension that specifies the offset of a set of clusters to hold the FDE headers, as well as the length of that region. The LUKS header is thus stored in these extra allocated clusters before the main image payload. Aside from all the cryptographic differences implied by use of the LUKS format, there is one further key difference between the use of legacy AES and LUKS encryption in qcow2. For LUKS, the initialiazation vectors are generated using the host physical sector as the input, rather than the guest virtual sector. This guarantees unique initialization vectors for all sectors when qcow2 internal snapshots are used, thus giving stronger protection against watermarking attacks. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170623162419.26068-14-berrange@redhat.com Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-06-23 18:24:12 +02:00
#define QCOW_CRYPT_LUKS 2
#define QCOW_MAX_CRYPT_CLUSTERS 32
#define QCOW_MAX_SNAPSHOTS 65536
/* Field widths in qcow2 mean normal cluster offsets cannot reach
* 64PB; depending on cluster size, compressed clusters can have a
* smaller limit (64PB for up to 16k clusters, then ramps down to
* 512TB for 2M clusters). */
#define QCOW_MAX_CLUSTER_OFFSET ((1ULL << 56) - 1)
/* 8 MB refcount table is enough for 2 PB images at 64k cluster size
* (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
#define QCOW_MAX_REFTABLE_SIZE (8 * MiB)
/* 32 MB L1 table is enough for 2 PB images at 64k cluster size
* (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
#define QCOW_MAX_L1_SIZE (32 * MiB)
/* Allow for an average of 1k per snapshot table entry, should be plenty of
* space for snapshot names and IDs */
#define QCOW_MAX_SNAPSHOTS_SIZE (1024 * QCOW_MAX_SNAPSHOTS)
/* Bitmap header extension constraints */
#define QCOW2_MAX_BITMAPS 65535
#define QCOW2_MAX_BITMAP_DIRECTORY_SIZE (1024 * QCOW2_MAX_BITMAPS)
/* indicate that the refcount of the referenced cluster is exactly one. */
#define QCOW_OFLAG_COPIED (1ULL << 63)
/* indicate that the cluster is compressed (they never have the copied flag) */
#define QCOW_OFLAG_COMPRESSED (1ULL << 62)
/* The cluster reads as all zeros */
#define QCOW_OFLAG_ZERO (1ULL << 0)
#define MIN_CLUSTER_BITS 9
#define MAX_CLUSTER_BITS 21
/* Must be at least 2 to cover COW */
qcow2: Allow configuring the L2 slice size Now that the code is ready to handle L2 slices we can finally add an option to allow configuring their size. An L2 slice is the portion of an L2 table that is read by the qcow2 cache. Until now the cache was always reading full L2 tables, and since the L2 table size is equal to the cluster size this was not very efficient with large clusters. Here's a more detailed explanation of why it makes sense to have smaller cache entries in order to load L2 data: https://lists.gnu.org/archive/html/qemu-block/2017-09/msg00635.html This patch introduces a new command-line option to the qcow2 driver named l2-cache-entry-size (cf. l2-cache-size). The cache entry size has the same restrictions as the cluster size: it must be a power of two and it has the same range of allowed values, with the additional requirement that it must not be larger than the cluster size. The L2 cache entry size (L2 slice size) remains equal to the cluster size for now by default, so this feature must be explicitly enabled. Although my tests show that 4KB slices consistently improve performance and give the best results, let's wait and make more tests with different cluster sizes before deciding on an optimal default. Now that the cache entry size is not necessarily equal to the cluster size we need to reflect that in the MIN_L2_CACHE_SIZE documentation. That minimum value is a requirement of the COW algorithm: we need to read two L2 slices (and not two L2 tables) in order to do COW, see l2_allocate() for the actual code. Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: c73e5611ff4a9ec5d20de68a6c289553a13d2354.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-05 15:33:36 +01:00
#define MIN_L2_CACHE_SIZE 2 /* cache entries */
/* Must be at least 4 to cover all cases of refcount table growth */
#define MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */
#ifdef CONFIG_LINUX
#define DEFAULT_L2_CACHE_MAX_SIZE (32 * MiB)
#define DEFAULT_CACHE_CLEAN_INTERVAL 600 /* seconds */
#else
#define DEFAULT_L2_CACHE_MAX_SIZE (8 * MiB)
/* Cache clean interval is currently available only on Linux, so must be 0 */
#define DEFAULT_CACHE_CLEAN_INTERVAL 0
#endif
#define DEFAULT_CLUSTER_SIZE 65536
#define QCOW2_OPT_LAZY_REFCOUNTS "lazy-refcounts"
#define QCOW2_OPT_DISCARD_REQUEST "pass-discard-request"
#define QCOW2_OPT_DISCARD_SNAPSHOT "pass-discard-snapshot"
#define QCOW2_OPT_DISCARD_OTHER "pass-discard-other"
#define QCOW2_OPT_OVERLAP "overlap-check"
#define QCOW2_OPT_OVERLAP_TEMPLATE "overlap-check.template"
#define QCOW2_OPT_OVERLAP_MAIN_HEADER "overlap-check.main-header"
#define QCOW2_OPT_OVERLAP_ACTIVE_L1 "overlap-check.active-l1"
#define QCOW2_OPT_OVERLAP_ACTIVE_L2 "overlap-check.active-l2"
#define QCOW2_OPT_OVERLAP_REFCOUNT_TABLE "overlap-check.refcount-table"
#define QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK "overlap-check.refcount-block"
#define QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE "overlap-check.snapshot-table"
#define QCOW2_OPT_OVERLAP_INACTIVE_L1 "overlap-check.inactive-l1"
#define QCOW2_OPT_OVERLAP_INACTIVE_L2 "overlap-check.inactive-l2"
#define QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY "overlap-check.bitmap-directory"
#define QCOW2_OPT_CACHE_SIZE "cache-size"
#define QCOW2_OPT_L2_CACHE_SIZE "l2-cache-size"
qcow2: Allow configuring the L2 slice size Now that the code is ready to handle L2 slices we can finally add an option to allow configuring their size. An L2 slice is the portion of an L2 table that is read by the qcow2 cache. Until now the cache was always reading full L2 tables, and since the L2 table size is equal to the cluster size this was not very efficient with large clusters. Here's a more detailed explanation of why it makes sense to have smaller cache entries in order to load L2 data: https://lists.gnu.org/archive/html/qemu-block/2017-09/msg00635.html This patch introduces a new command-line option to the qcow2 driver named l2-cache-entry-size (cf. l2-cache-size). The cache entry size has the same restrictions as the cluster size: it must be a power of two and it has the same range of allowed values, with the additional requirement that it must not be larger than the cluster size. The L2 cache entry size (L2 slice size) remains equal to the cluster size for now by default, so this feature must be explicitly enabled. Although my tests show that 4KB slices consistently improve performance and give the best results, let's wait and make more tests with different cluster sizes before deciding on an optimal default. Now that the cache entry size is not necessarily equal to the cluster size we need to reflect that in the MIN_L2_CACHE_SIZE documentation. That minimum value is a requirement of the COW algorithm: we need to read two L2 slices (and not two L2 tables) in order to do COW, see l2_allocate() for the actual code. Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: c73e5611ff4a9ec5d20de68a6c289553a13d2354.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-05 15:33:36 +01:00
#define QCOW2_OPT_L2_CACHE_ENTRY_SIZE "l2-cache-entry-size"
#define QCOW2_OPT_REFCOUNT_CACHE_SIZE "refcount-cache-size"
#define QCOW2_OPT_CACHE_CLEAN_INTERVAL "cache-clean-interval"
typedef struct QCowHeader {
uint32_t magic;
uint32_t version;
uint64_t backing_file_offset;
uint32_t backing_file_size;
uint32_t cluster_bits;
uint64_t size; /* in bytes */
uint32_t crypt_method;
uint32_t l1_size; /* XXX: save number of clusters instead ? */
uint64_t l1_table_offset;
uint64_t refcount_table_offset;
uint32_t refcount_table_clusters;
uint32_t nb_snapshots;
uint64_t snapshots_offset;
/* The following fields are only valid for version >= 3 */
uint64_t incompatible_features;
uint64_t compatible_features;
uint64_t autoclear_features;
uint32_t refcount_order;
uint32_t header_length;
} QEMU_PACKED QCowHeader;
typedef struct QEMU_PACKED QCowSnapshotHeader {
/* header is 8 byte aligned */
uint64_t l1_table_offset;
uint32_t l1_size;
uint16_t id_str_size;
uint16_t name_size;
uint32_t date_sec;
uint32_t date_nsec;
uint64_t vm_clock_nsec;
uint32_t vm_state_size;
uint32_t extra_data_size; /* for extension */
/* extra data follows */
/* id_str follows */
/* name follows */
} QCowSnapshotHeader;
typedef struct QEMU_PACKED QCowSnapshotExtraData {
uint64_t vm_state_size_large;
uint64_t disk_size;
} QCowSnapshotExtraData;
typedef struct QCowSnapshot {
uint64_t l1_table_offset;
uint32_t l1_size;
char *id_str;
char *name;
uint64_t disk_size;
uint64_t vm_state_size;
uint32_t date_sec;
uint32_t date_nsec;
uint64_t vm_clock_nsec;
} QCowSnapshot;
struct Qcow2Cache;
typedef struct Qcow2Cache Qcow2Cache;
qcow2: add support for LUKS encryption format This adds support for using LUKS as an encryption format with the qcow2 file, using the new encrypt.format parameter to request "luks" format. e.g. # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encrypt.format=luks,encrypt.key-secret=sec0 \ test.qcow2 10G The legacy "encryption=on" parameter still results in creation of the old qcow2 AES format (and is equivalent to the new 'encryption-format=aes'). e.g. the following are equivalent: # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption=on,encrypt.key-secret=sec0 \ test.qcow2 10G # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption-format=aes,encrypt.key-secret=sec0 \ test.qcow2 10G With the LUKS format it is necessary to store the LUKS partition header and key material in the QCow2 file. This data can be many MB in size, so cannot go into the QCow2 header region directly. Thus the spec defines a FDE (Full Disk Encryption) header extension that specifies the offset of a set of clusters to hold the FDE headers, as well as the length of that region. The LUKS header is thus stored in these extra allocated clusters before the main image payload. Aside from all the cryptographic differences implied by use of the LUKS format, there is one further key difference between the use of legacy AES and LUKS encryption in qcow2. For LUKS, the initialiazation vectors are generated using the host physical sector as the input, rather than the guest virtual sector. This guarantees unique initialization vectors for all sectors when qcow2 internal snapshots are used, thus giving stronger protection against watermarking attacks. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170623162419.26068-14-berrange@redhat.com Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-06-23 18:24:12 +02:00
typedef struct Qcow2CryptoHeaderExtension {
uint64_t offset;
uint64_t length;
} QEMU_PACKED Qcow2CryptoHeaderExtension;
typedef struct Qcow2UnknownHeaderExtension {
uint32_t magic;
uint32_t len;
QLIST_ENTRY(Qcow2UnknownHeaderExtension) next;
uint8_t data[];
} Qcow2UnknownHeaderExtension;
enum {
QCOW2_FEAT_TYPE_INCOMPATIBLE = 0,
QCOW2_FEAT_TYPE_COMPATIBLE = 1,
QCOW2_FEAT_TYPE_AUTOCLEAR = 2,
};
/* Incompatible feature bits */
enum {
QCOW2_INCOMPAT_DIRTY_BITNR = 0,
QCOW2_INCOMPAT_CORRUPT_BITNR = 1,
QCOW2_INCOMPAT_DIRTY = 1 << QCOW2_INCOMPAT_DIRTY_BITNR,
QCOW2_INCOMPAT_CORRUPT = 1 << QCOW2_INCOMPAT_CORRUPT_BITNR,
QCOW2_INCOMPAT_MASK = QCOW2_INCOMPAT_DIRTY
| QCOW2_INCOMPAT_CORRUPT,
};
/* Compatible feature bits */
enum {
QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR = 0,
QCOW2_COMPAT_LAZY_REFCOUNTS = 1 << QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
QCOW2_COMPAT_FEAT_MASK = QCOW2_COMPAT_LAZY_REFCOUNTS,
};
/* Autoclear feature bits */
enum {
QCOW2_AUTOCLEAR_BITMAPS_BITNR = 0,
QCOW2_AUTOCLEAR_BITMAPS = 1 << QCOW2_AUTOCLEAR_BITMAPS_BITNR,
QCOW2_AUTOCLEAR_MASK = QCOW2_AUTOCLEAR_BITMAPS,
};
enum qcow2_discard_type {
QCOW2_DISCARD_NEVER = 0,
QCOW2_DISCARD_ALWAYS,
QCOW2_DISCARD_REQUEST,
QCOW2_DISCARD_SNAPSHOT,
QCOW2_DISCARD_OTHER,
QCOW2_DISCARD_MAX
};
typedef struct Qcow2Feature {
uint8_t type;
uint8_t bit;
char name[46];
} QEMU_PACKED Qcow2Feature;
typedef struct Qcow2DiscardRegion {
BlockDriverState *bs;
uint64_t offset;
uint64_t bytes;
QTAILQ_ENTRY(Qcow2DiscardRegion) next;
} Qcow2DiscardRegion;
typedef uint64_t Qcow2GetRefcountFunc(const void *refcount_array,
uint64_t index);
typedef void Qcow2SetRefcountFunc(void *refcount_array,
uint64_t index, uint64_t value);
typedef struct Qcow2BitmapHeaderExt {
uint32_t nb_bitmaps;
uint32_t reserved32;
uint64_t bitmap_directory_size;
uint64_t bitmap_directory_offset;
} QEMU_PACKED Qcow2BitmapHeaderExt;
typedef struct BDRVQcow2State {
int cluster_bits;
int cluster_size;
int cluster_sectors;
int l2_slice_size;
int l2_bits;
int l2_size;
int l1_size;
int l1_vm_state_index;
int refcount_block_bits;
int refcount_block_size;
int csize_shift;
int csize_mask;
uint64_t cluster_offset_mask;
uint64_t l1_table_offset;
uint64_t *l1_table;
Qcow2Cache* l2_table_cache;
Qcow2Cache* refcount_block_cache;
QEMUTimer *cache_clean_timer;
unsigned cache_clean_interval;
uint8_t *cluster_cache;
uint8_t *cluster_data;
uint64_t cluster_cache_offset;
QLIST_HEAD(, QCowL2Meta) cluster_allocs;
uint64_t *refcount_table;
uint64_t refcount_table_offset;
uint32_t refcount_table_size;
uint32_t max_refcount_table_index; /* Last used entry in refcount_table */
uint64_t free_cluster_index;
uint64_t free_byte_offset;
CoMutex lock;
qcow2: add support for LUKS encryption format This adds support for using LUKS as an encryption format with the qcow2 file, using the new encrypt.format parameter to request "luks" format. e.g. # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encrypt.format=luks,encrypt.key-secret=sec0 \ test.qcow2 10G The legacy "encryption=on" parameter still results in creation of the old qcow2 AES format (and is equivalent to the new 'encryption-format=aes'). e.g. the following are equivalent: # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption=on,encrypt.key-secret=sec0 \ test.qcow2 10G # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption-format=aes,encrypt.key-secret=sec0 \ test.qcow2 10G With the LUKS format it is necessary to store the LUKS partition header and key material in the QCow2 file. This data can be many MB in size, so cannot go into the QCow2 header region directly. Thus the spec defines a FDE (Full Disk Encryption) header extension that specifies the offset of a set of clusters to hold the FDE headers, as well as the length of that region. The LUKS header is thus stored in these extra allocated clusters before the main image payload. Aside from all the cryptographic differences implied by use of the LUKS format, there is one further key difference between the use of legacy AES and LUKS encryption in qcow2. For LUKS, the initialiazation vectors are generated using the host physical sector as the input, rather than the guest virtual sector. This guarantees unique initialization vectors for all sectors when qcow2 internal snapshots are used, thus giving stronger protection against watermarking attacks. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170623162419.26068-14-berrange@redhat.com Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-06-23 18:24:12 +02:00
Qcow2CryptoHeaderExtension crypto_header; /* QCow2 header extension */
QCryptoBlockOpenOptions *crypto_opts; /* Disk encryption runtime options */
QCryptoBlock *crypto; /* Disk encryption format driver */
qcow2: add support for LUKS encryption format This adds support for using LUKS as an encryption format with the qcow2 file, using the new encrypt.format parameter to request "luks" format. e.g. # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encrypt.format=luks,encrypt.key-secret=sec0 \ test.qcow2 10G The legacy "encryption=on" parameter still results in creation of the old qcow2 AES format (and is equivalent to the new 'encryption-format=aes'). e.g. the following are equivalent: # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption=on,encrypt.key-secret=sec0 \ test.qcow2 10G # qemu-img create --object secret,data=123456,id=sec0 \ -f qcow2 -o encryption-format=aes,encrypt.key-secret=sec0 \ test.qcow2 10G With the LUKS format it is necessary to store the LUKS partition header and key material in the QCow2 file. This data can be many MB in size, so cannot go into the QCow2 header region directly. Thus the spec defines a FDE (Full Disk Encryption) header extension that specifies the offset of a set of clusters to hold the FDE headers, as well as the length of that region. The LUKS header is thus stored in these extra allocated clusters before the main image payload. Aside from all the cryptographic differences implied by use of the LUKS format, there is one further key difference between the use of legacy AES and LUKS encryption in qcow2. For LUKS, the initialiazation vectors are generated using the host physical sector as the input, rather than the guest virtual sector. This guarantees unique initialization vectors for all sectors when qcow2 internal snapshots are used, thus giving stronger protection against watermarking attacks. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20170623162419.26068-14-berrange@redhat.com Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-06-23 18:24:12 +02:00
bool crypt_physical_offset; /* Whether to use virtual or physical offset
for encryption initialization vector tweak */
uint32_t crypt_method_header;
uint64_t snapshots_offset;
int snapshots_size;
unsigned int nb_snapshots;
QCowSnapshot *snapshots;
uint32_t nb_bitmaps;
uint64_t bitmap_directory_size;
uint64_t bitmap_directory_offset;
int flags;
int qcow_version;
bool use_lazy_refcounts;
int refcount_order;
int refcount_bits;
uint64_t refcount_max;
Qcow2GetRefcountFunc *get_refcount;
Qcow2SetRefcountFunc *set_refcount;
bool discard_passthrough[QCOW2_DISCARD_MAX];
int overlap_check; /* bitmask of Qcow2MetadataOverlap values */
bool signaled_corruption;
uint64_t incompatible_features;
uint64_t compatible_features;
uint64_t autoclear_features;
size_t unknown_header_fields_size;
void* unknown_header_fields;
QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
QTAILQ_HEAD (, Qcow2DiscardRegion) discards;
bool cache_discards;
/* Backing file path and format as stored in the image (this is not the
* effective path/format, which may be the result of a runtime option
* override) */
char *image_backing_file;
char *image_backing_format;
CoQueue compress_wait_queue;
int nb_compress_threads;
} BDRVQcow2State;
typedef struct Qcow2COWRegion {
/**
* Offset of the COW region in bytes from the start of the first cluster
* touched by the request.
*/
unsigned offset;
/** Number of bytes to copy */
unsigned nb_bytes;
} Qcow2COWRegion;
/**
* Describes an in-flight (part of a) write request that writes to clusters
* that are not referenced in their L2 table yet.
*/
typedef struct QCowL2Meta
{
/** Guest offset of the first newly allocated cluster */
uint64_t offset;
/** Host offset of the first newly allocated cluster */
uint64_t alloc_offset;
/** Number of newly allocated clusters */
int nb_clusters;
/** Do not free the old clusters */
bool keep_old_clusters;
/**
* Requests that overlap with this allocation and wait to be restarted
* when the allocating request has completed.
*/
CoQueue dependent_requests;
/**
* The COW Region between the start of the first allocated cluster and the
* area the guest actually writes to.
*/
Qcow2COWRegion cow_start;
/**
* The COW Region between the area the guest actually writes to and the
* end of the last allocated cluster.
*/
Qcow2COWRegion cow_end;
/**
* The I/O vector with the data from the actual guest write request.
* If non-NULL, this is meant to be merged together with the data
* from @cow_start and @cow_end into one single write operation.
*/
QEMUIOVector *data_qiov;
/** Pointer to next L2Meta of the same write request */
struct QCowL2Meta *next;
QLIST_ENTRY(QCowL2Meta) next_in_flight;
} QCowL2Meta;
typedef enum QCow2ClusterType {
QCOW2_CLUSTER_UNALLOCATED,
QCOW2_CLUSTER_ZERO_PLAIN,
QCOW2_CLUSTER_ZERO_ALLOC,
QCOW2_CLUSTER_NORMAL,
QCOW2_CLUSTER_COMPRESSED,
} QCow2ClusterType;
typedef enum QCow2MetadataOverlap {
QCOW2_OL_MAIN_HEADER_BITNR = 0,
QCOW2_OL_ACTIVE_L1_BITNR = 1,
QCOW2_OL_ACTIVE_L2_BITNR = 2,
QCOW2_OL_REFCOUNT_TABLE_BITNR = 3,
QCOW2_OL_REFCOUNT_BLOCK_BITNR = 4,
QCOW2_OL_SNAPSHOT_TABLE_BITNR = 5,
QCOW2_OL_INACTIVE_L1_BITNR = 6,
QCOW2_OL_INACTIVE_L2_BITNR = 7,
QCOW2_OL_BITMAP_DIRECTORY_BITNR = 8,
QCOW2_OL_MAX_BITNR = 9,
QCOW2_OL_NONE = 0,
QCOW2_OL_MAIN_HEADER = (1 << QCOW2_OL_MAIN_HEADER_BITNR),
QCOW2_OL_ACTIVE_L1 = (1 << QCOW2_OL_ACTIVE_L1_BITNR),
QCOW2_OL_ACTIVE_L2 = (1 << QCOW2_OL_ACTIVE_L2_BITNR),
QCOW2_OL_REFCOUNT_TABLE = (1 << QCOW2_OL_REFCOUNT_TABLE_BITNR),
QCOW2_OL_REFCOUNT_BLOCK = (1 << QCOW2_OL_REFCOUNT_BLOCK_BITNR),
QCOW2_OL_SNAPSHOT_TABLE = (1 << QCOW2_OL_SNAPSHOT_TABLE_BITNR),
QCOW2_OL_INACTIVE_L1 = (1 << QCOW2_OL_INACTIVE_L1_BITNR),
/* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
* reads. */
QCOW2_OL_INACTIVE_L2 = (1 << QCOW2_OL_INACTIVE_L2_BITNR),
QCOW2_OL_BITMAP_DIRECTORY = (1 << QCOW2_OL_BITMAP_DIRECTORY_BITNR),
} QCow2MetadataOverlap;
/* Perform all overlap checks which can be done in constant time */
#define QCOW2_OL_CONSTANT \
(QCOW2_OL_MAIN_HEADER | QCOW2_OL_ACTIVE_L1 | QCOW2_OL_REFCOUNT_TABLE | \
QCOW2_OL_SNAPSHOT_TABLE | QCOW2_OL_BITMAP_DIRECTORY)
/* Perform all overlap checks which don't require disk access */
#define QCOW2_OL_CACHED \
(QCOW2_OL_CONSTANT | QCOW2_OL_ACTIVE_L2 | QCOW2_OL_REFCOUNT_BLOCK | \
QCOW2_OL_INACTIVE_L1)
/* Perform all overlap checks */
#define QCOW2_OL_ALL \
(QCOW2_OL_CACHED | QCOW2_OL_INACTIVE_L2)
#define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
#define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
#define L2E_COMPRESSED_OFFSET_SIZE_MASK 0x3fffffffffffffffULL
#define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
static inline int64_t start_of_cluster(BDRVQcow2State *s, int64_t offset)
{
return offset & ~(s->cluster_size - 1);
}
static inline int64_t offset_into_cluster(BDRVQcow2State *s, int64_t offset)
{
return offset & (s->cluster_size - 1);
}
static inline uint64_t size_to_clusters(BDRVQcow2State *s, uint64_t size)
{
return (size + (s->cluster_size - 1)) >> s->cluster_bits;
}
static inline int64_t size_to_l1(BDRVQcow2State *s, int64_t size)
{
int shift = s->cluster_bits + s->l2_bits;
return (size + (1ULL << shift) - 1) >> shift;
}
static inline int offset_to_l1_index(BDRVQcow2State *s, uint64_t offset)
{
return offset >> (s->l2_bits + s->cluster_bits);
}
static inline int offset_to_l2_index(BDRVQcow2State *s, int64_t offset)
{
return (offset >> s->cluster_bits) & (s->l2_size - 1);
}
static inline int offset_to_l2_slice_index(BDRVQcow2State *s, int64_t offset)
{
return (offset >> s->cluster_bits) & (s->l2_slice_size - 1);
}
static inline int64_t qcow2_vm_state_offset(BDRVQcow2State *s)
{
return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits);
}
static inline QCow2ClusterType qcow2_get_cluster_type(uint64_t l2_entry)
{
if (l2_entry & QCOW_OFLAG_COMPRESSED) {
return QCOW2_CLUSTER_COMPRESSED;
} else if (l2_entry & QCOW_OFLAG_ZERO) {
if (l2_entry & L2E_OFFSET_MASK) {
return QCOW2_CLUSTER_ZERO_ALLOC;
}
return QCOW2_CLUSTER_ZERO_PLAIN;
} else if (!(l2_entry & L2E_OFFSET_MASK)) {
return QCOW2_CLUSTER_UNALLOCATED;
} else {
return QCOW2_CLUSTER_NORMAL;
}
}
/* Check whether refcounts are eager or lazy */
static inline bool qcow2_need_accurate_refcounts(BDRVQcow2State *s)
{
return !(s->incompatible_features & QCOW2_INCOMPAT_DIRTY);
}
static inline uint64_t l2meta_cow_start(QCowL2Meta *m)
{
return m->offset + m->cow_start.offset;
}
static inline uint64_t l2meta_cow_end(QCowL2Meta *m)
{
return m->offset + m->cow_end.offset + m->cow_end.nb_bytes;
}
static inline uint64_t refcount_diff(uint64_t r1, uint64_t r2)
{
return r1 > r2 ? r1 - r2 : r2 - r1;
}
static inline
uint32_t offset_to_reftable_index(BDRVQcow2State *s, uint64_t offset)
{
return offset >> (s->refcount_block_bits + s->cluster_bits);
}
/* qcow2.c functions */
int64_t qcow2_refcount_metadata_size(int64_t clusters, size_t cluster_size,
int refcount_order, bool generous_increase,
uint64_t *refblock_count);
int qcow2_mark_dirty(BlockDriverState *bs);
int qcow2_mark_corrupt(BlockDriverState *bs);
int qcow2_mark_consistent(BlockDriverState *bs);
int qcow2_update_header(BlockDriverState *bs);
void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset,
int64_t size, const char *message_format, ...)
GCC_FMT_ATTR(5, 6);
int qcow2_validate_table(BlockDriverState *bs, uint64_t offset,
uint64_t entries, size_t entry_len,
int64_t max_size_bytes, const char *table_name,
Error **errp);
/* qcow2-refcount.c functions */
int qcow2_refcount_init(BlockDriverState *bs);
void qcow2_refcount_close(BlockDriverState *bs);
int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index,
uint64_t *refcount);
int qcow2_update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index,
uint64_t addend, bool decrease,
enum qcow2_discard_type type);
int64_t qcow2_refcount_area(BlockDriverState *bs, uint64_t offset,
uint64_t additional_clusters, bool exact_size,
int new_refblock_index,
uint64_t new_refblock_offset);
int64_t qcow2_alloc_clusters(BlockDriverState *bs, uint64_t size);
int64_t qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
int64_t nb_clusters);
int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
void qcow2_free_clusters(BlockDriverState *bs,
int64_t offset, int64_t size,
enum qcow2_discard_type type);
void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
int nb_clusters, enum qcow2_discard_type type);
int qcow2_update_snapshot_refcount(BlockDriverState *bs,
int64_t l1_table_offset, int l1_size, int addend);
int coroutine_fn qcow2_flush_caches(BlockDriverState *bs);
int coroutine_fn qcow2_write_caches(BlockDriverState *bs);
int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
BdrvCheckMode fix);
void qcow2_process_discards(BlockDriverState *bs, int ret);
int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
int64_t size);
int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
int64_t size);
int qcow2_inc_refcounts_imrt(BlockDriverState *bs, BdrvCheckResult *res,
void **refcount_table,
int64_t *refcount_table_size,
int64_t offset, int64_t size);
int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
BlockDriverAmendStatusCB *status_cb,
void *cb_opaque, Error **errp);
int qcow2_shrink_reftable(BlockDriverState *bs);
int64_t qcow2_get_last_cluster(BlockDriverState *bs, int64_t size);
/* qcow2-cluster.c functions */
int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
bool exact_size);
int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t max_size);
int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
int qcow2_encrypt_sectors(BDRVQcow2State *s, int64_t sector_num,
uint8_t *buf, int nb_sectors, bool enc, Error **errp);
int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
unsigned int *bytes, uint64_t *cluster_offset);
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
unsigned int *bytes, uint64_t *host_offset,
QCowL2Meta **m);
uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int compressed_size);
int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m);
int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, enum qcow2_discard_type type,
bool full_discard);
int qcow2_cluster_zeroize(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, int flags);
int qcow2_expand_zero_clusters(BlockDriverState *bs,
BlockDriverAmendStatusCB *status_cb,
void *cb_opaque);
/* qcow2-snapshot.c functions */
int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id);
int qcow2_snapshot_delete(BlockDriverState *bs,
const char *snapshot_id,
const char *name,
Error **errp);
int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab);
int qcow2_snapshot_load_tmp(BlockDriverState *bs,
const char *snapshot_id,
const char *name,
Error **errp);
void qcow2_free_snapshots(BlockDriverState *bs);
int qcow2_read_snapshots(BlockDriverState *bs);
/* qcow2-cache.c functions */
qcow2: Allow configuring the L2 slice size Now that the code is ready to handle L2 slices we can finally add an option to allow configuring their size. An L2 slice is the portion of an L2 table that is read by the qcow2 cache. Until now the cache was always reading full L2 tables, and since the L2 table size is equal to the cluster size this was not very efficient with large clusters. Here's a more detailed explanation of why it makes sense to have smaller cache entries in order to load L2 data: https://lists.gnu.org/archive/html/qemu-block/2017-09/msg00635.html This patch introduces a new command-line option to the qcow2 driver named l2-cache-entry-size (cf. l2-cache-size). The cache entry size has the same restrictions as the cluster size: it must be a power of two and it has the same range of allowed values, with the additional requirement that it must not be larger than the cluster size. The L2 cache entry size (L2 slice size) remains equal to the cluster size for now by default, so this feature must be explicitly enabled. Although my tests show that 4KB slices consistently improve performance and give the best results, let's wait and make more tests with different cluster sizes before deciding on an optimal default. Now that the cache entry size is not necessarily equal to the cluster size we need to reflect that in the MIN_L2_CACHE_SIZE documentation. That minimum value is a requirement of the COW algorithm: we need to read two L2 slices (and not two L2 tables) in order to do COW, see l2_allocate() for the actual code. Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: c73e5611ff4a9ec5d20de68a6c289553a13d2354.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-05 15:33:36 +01:00
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables,
unsigned table_size);
int qcow2_cache_destroy(Qcow2Cache *c);
void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table);
int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c);
int qcow2_cache_write(BlockDriverState *bs, Qcow2Cache *c);
int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
Qcow2Cache *dependency);
void qcow2_cache_depends_on_flush(Qcow2Cache *c);
void qcow2_cache_clean_unused(Qcow2Cache *c);
int qcow2_cache_empty(BlockDriverState *bs, Qcow2Cache *c);
int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
void **table);
int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
void **table);
void qcow2_cache_put(Qcow2Cache *c, void **table);
void *qcow2_cache_is_table_offset(Qcow2Cache *c, uint64_t offset);
void qcow2_cache_discard(Qcow2Cache *c, void *table);
/* qcow2-bitmap.c functions */
int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
void **refcount_table,
int64_t *refcount_table_size);
bool qcow2_load_dirty_bitmaps(BlockDriverState *bs, Error **errp);
Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
Error **errp);
int qcow2_reopen_bitmaps_rw_hint(BlockDriverState *bs, bool *header_updated,
Error **errp);
int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp);
void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp);
int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp);
bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
const char *name,
uint32_t granularity,
Error **errp);
void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
const char *name,
Error **errp);
#endif