blob: b5c47931ef4ac64f696263558d3c0f348f1a1140 [file] [log] [blame]
/*
* 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.
*/
#include "qemu/osdep.h"
#include "block/qdict.h"
#include "sysemu/block-backend.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "qcow2.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "qapi/qapi-events-block-core.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qstring.h"
#include "trace.h"
#include "qemu/option_int.h"
#include "qemu/cutils.h"
#include "qemu/bswap.h"
#include "qemu/memalign.h"
#include "qapi/qobject-input-visitor.h"
#include "qapi/qapi-visit-block-core.h"
#include "crypto.h"
#include "block/aio_task.h"
/*
Differences with QCOW:
- Support for multiple incremental snapshots.
- Memory management by reference counts.
- Clusters which have a reference count of one have the bit
QCOW_OFLAG_COPIED to optimize write performance.
- Size of compressed clusters is stored in sectors to reduce bit usage
in the cluster offsets.
- Support for storing additional data (such as the VM state) in the
snapshots.
- If a backing store is used, the cluster size is not constrained
(could be backported to QCOW).
- L2 tables have always a size of one cluster.
*/
typedef struct {
uint32_t magic;
uint32_t len;
} QEMU_PACKED QCowExtension;
#define QCOW2_EXT_MAGIC_END 0
#define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xe2792aca
#define QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
#define QCOW2_EXT_MAGIC_CRYPTO_HEADER 0x0537be77
#define QCOW2_EXT_MAGIC_BITMAPS 0x23852875
#define QCOW2_EXT_MAGIC_DATA_FILE 0x44415441
static int coroutine_fn
qcow2_co_preadv_compressed(BlockDriverState *bs,
uint64_t l2_entry,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
size_t qiov_offset);
static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename)
{
const QCowHeader *cow_header = (const void *)buf;
if (buf_size >= sizeof(QCowHeader) &&
be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
be32_to_cpu(cow_header->version) >= 2)
return 100;
else
return 0;
}
static ssize_t qcow2_crypto_hdr_read_func(QCryptoBlock *block, size_t offset,
uint8_t *buf, size_t buflen,
void *opaque, Error **errp)
{
BlockDriverState *bs = opaque;
BDRVQcow2State *s = bs->opaque;
ssize_t ret;
if ((offset + buflen) > s->crypto_header.length) {
error_setg(errp, "Request for data outside of extension header");
return -1;
}
ret = bdrv_pread(bs->file,
s->crypto_header.offset + offset, buf, buflen);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read encryption header");
return -1;
}
return ret;
}
static ssize_t qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen,
void *opaque, Error **errp)
{
BlockDriverState *bs = opaque;
BDRVQcow2State *s = bs->opaque;
int64_t ret;
int64_t clusterlen;
ret = qcow2_alloc_clusters(bs, headerlen);
if (ret < 0) {
error_setg_errno(errp, -ret,
"Cannot allocate cluster for LUKS header size %zu",
headerlen);
return -1;
}
s->crypto_header.length = headerlen;
s->crypto_header.offset = ret;
/*
* Zero fill all space in cluster so it has predictable
* content, as we may not initialize some regions of the
* header (eg only 1 out of 8 key slots will be initialized)
*/
clusterlen = size_to_clusters(s, headerlen) * s->cluster_size;
assert(qcow2_pre_write_overlap_check(bs, 0, ret, clusterlen, false) == 0);
ret = bdrv_pwrite_zeroes(bs->file,
ret,
clusterlen, 0);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not zero fill encryption header");
return -1;
}
return ret;
}
static ssize_t qcow2_crypto_hdr_write_func(QCryptoBlock *block, size_t offset,
const uint8_t *buf, size_t buflen,
void *opaque, Error **errp)
{
BlockDriverState *bs = opaque;
BDRVQcow2State *s = bs->opaque;
ssize_t ret;
if ((offset + buflen) > s->crypto_header.length) {
error_setg(errp, "Request for data outside of extension header");
return -1;
}
ret = bdrv_pwrite(bs->file,
s->crypto_header.offset + offset, buf, buflen);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read encryption header");
return -1;
}
return ret;
}
static QDict*
qcow2_extract_crypto_opts(QemuOpts *opts, const char *fmt, Error **errp)
{
QDict *cryptoopts_qdict;
QDict *opts_qdict;
/* Extract "encrypt." options into a qdict */
opts_qdict = qemu_opts_to_qdict(opts, NULL);
qdict_extract_subqdict(opts_qdict, &cryptoopts_qdict, "encrypt.");
qobject_unref(opts_qdict);
qdict_put_str(cryptoopts_qdict, "format", fmt);
return cryptoopts_qdict;
}
/*
* read qcow2 extension and fill bs
* start reading from start_offset
* finish reading upon magic of value 0 or when end_offset reached
* unknown magic is skipped (future extension this version knows nothing about)
* return 0 upon success, non-0 otherwise
*/
static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
uint64_t end_offset, void **p_feature_table,
int flags, bool *need_update_header,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
QCowExtension ext;
uint64_t offset;
int ret;
Qcow2BitmapHeaderExt bitmaps_ext;
if (need_update_header != NULL) {
*need_update_header = false;
}
#ifdef DEBUG_EXT
printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
#endif
offset = start_offset;
while (offset < end_offset) {
#ifdef DEBUG_EXT
/* Sanity check */
if (offset > s->cluster_size)
printf("qcow2_read_extension: suspicious offset %lu\n", offset);
printf("attempting to read extended header in offset %lu\n", offset);
#endif
ret = bdrv_pread(bs->file, offset, &ext, sizeof(ext));
if (ret < 0) {
error_setg_errno(errp, -ret, "qcow2_read_extension: ERROR: "
"pread fail from offset %" PRIu64, offset);
return 1;
}
ext.magic = be32_to_cpu(ext.magic);
ext.len = be32_to_cpu(ext.len);
offset += sizeof(ext);
#ifdef DEBUG_EXT
printf("ext.magic = 0x%x\n", ext.magic);
#endif
if (offset > end_offset || ext.len > end_offset - offset) {
error_setg(errp, "Header extension too large");
return -EINVAL;
}
switch (ext.magic) {
case QCOW2_EXT_MAGIC_END:
return 0;
case QCOW2_EXT_MAGIC_BACKING_FORMAT:
if (ext.len >= sizeof(bs->backing_format)) {
error_setg(errp, "ERROR: ext_backing_format: len=%" PRIu32
" too large (>=%zu)", ext.len,
sizeof(bs->backing_format));
return 2;
}
ret = bdrv_pread(bs->file, offset, bs->backing_format, ext.len);
if (ret < 0) {
error_setg_errno(errp, -ret, "ERROR: ext_backing_format: "
"Could not read format name");
return 3;
}
bs->backing_format[ext.len] = '\0';
s->image_backing_format = g_strdup(bs->backing_format);
#ifdef DEBUG_EXT
printf("Qcow2: Got format extension %s\n", bs->backing_format);
#endif
break;
case QCOW2_EXT_MAGIC_FEATURE_TABLE:
if (p_feature_table != NULL) {
void *feature_table = g_malloc0(ext.len + 2 * sizeof(Qcow2Feature));
ret = bdrv_pread(bs->file, offset , feature_table, ext.len);
if (ret < 0) {
error_setg_errno(errp, -ret, "ERROR: ext_feature_table: "
"Could not read table");
return ret;
}
*p_feature_table = feature_table;
}
break;
case QCOW2_EXT_MAGIC_CRYPTO_HEADER: {
unsigned int cflags = 0;
if (s->crypt_method_header != QCOW_CRYPT_LUKS) {
error_setg(errp, "CRYPTO header extension only "
"expected with LUKS encryption method");
return -EINVAL;
}
if (ext.len != sizeof(Qcow2CryptoHeaderExtension)) {
error_setg(errp, "CRYPTO header extension size %u, "
"but expected size %zu", ext.len,
sizeof(Qcow2CryptoHeaderExtension));
return -EINVAL;
}
ret = bdrv_pread(bs->file, offset, &s->crypto_header, ext.len);
if (ret < 0) {
error_setg_errno(errp, -ret,
"Unable to read CRYPTO header extension");
return ret;
}
s->crypto_header.offset = be64_to_cpu(s->crypto_header.offset);
s->crypto_header.length = be64_to_cpu(s->crypto_header.length);
if ((s->crypto_header.offset % s->cluster_size) != 0) {
error_setg(errp, "Encryption header offset '%" PRIu64 "' is "
"not a multiple of cluster size '%u'",
s->crypto_header.offset, s->cluster_size);
return -EINVAL;
}
if (flags & BDRV_O_NO_IO) {
cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
}
s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
qcow2_crypto_hdr_read_func,
bs, cflags, QCOW2_MAX_THREADS, errp);
if (!s->crypto) {
return -EINVAL;
}
} break;
case QCOW2_EXT_MAGIC_BITMAPS:
if (ext.len != sizeof(bitmaps_ext)) {
error_setg_errno(errp, -ret, "bitmaps_ext: "
"Invalid extension length");
return -EINVAL;
}
if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS)) {
if (s->qcow_version < 3) {
/* Let's be a bit more specific */
warn_report("This qcow2 v2 image contains bitmaps, but "
"they may have been modified by a program "
"without persistent bitmap support; so now "
"they must all be considered inconsistent");
} else {
warn_report("a program lacking bitmap support "
"modified this file, so all bitmaps are now "
"considered inconsistent");
}
error_printf("Some clusters may be leaked, "
"run 'qemu-img check -r' on the image "
"file to fix.");
if (need_update_header != NULL) {
/* Updating is needed to drop invalid bitmap extension. */
*need_update_header = true;
}
break;
}
ret = bdrv_pread(bs->file, offset, &bitmaps_ext, ext.len);
if (ret < 0) {
error_setg_errno(errp, -ret, "bitmaps_ext: "
"Could not read ext header");
return ret;
}
if (bitmaps_ext.reserved32 != 0) {
error_setg_errno(errp, -ret, "bitmaps_ext: "
"Reserved field is not zero");
return -EINVAL;
}
bitmaps_ext.nb_bitmaps = be32_to_cpu(bitmaps_ext.nb_bitmaps);
bitmaps_ext.bitmap_directory_size =
be64_to_cpu(bitmaps_ext.bitmap_directory_size);
bitmaps_ext.bitmap_directory_offset =
be64_to_cpu(bitmaps_ext.bitmap_directory_offset);
if (bitmaps_ext.nb_bitmaps > QCOW2_MAX_BITMAPS) {
error_setg(errp,
"bitmaps_ext: Image has %" PRIu32 " bitmaps, "
"exceeding the QEMU supported maximum of %d",
bitmaps_ext.nb_bitmaps, QCOW2_MAX_BITMAPS);
return -EINVAL;
}
if (bitmaps_ext.nb_bitmaps == 0) {
error_setg(errp, "found bitmaps extension with zero bitmaps");
return -EINVAL;
}
if (offset_into_cluster(s, bitmaps_ext.bitmap_directory_offset)) {
error_setg(errp, "bitmaps_ext: "
"invalid bitmap directory offset");
return -EINVAL;
}
if (bitmaps_ext.bitmap_directory_size >
QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
error_setg(errp, "bitmaps_ext: "
"bitmap directory size (%" PRIu64 ") exceeds "
"the maximum supported size (%d)",
bitmaps_ext.bitmap_directory_size,
QCOW2_MAX_BITMAP_DIRECTORY_SIZE);
return -EINVAL;
}
s->nb_bitmaps = bitmaps_ext.nb_bitmaps;
s->bitmap_directory_offset =
bitmaps_ext.bitmap_directory_offset;
s->bitmap_directory_size =
bitmaps_ext.bitmap_directory_size;
#ifdef DEBUG_EXT
printf("Qcow2: Got bitmaps extension: "
"offset=%" PRIu64 " nb_bitmaps=%" PRIu32 "\n",
s->bitmap_directory_offset, s->nb_bitmaps);
#endif
break;
case QCOW2_EXT_MAGIC_DATA_FILE:
{
s->image_data_file = g_malloc0(ext.len + 1);
ret = bdrv_pread(bs->file, offset, s->image_data_file, ext.len);
if (ret < 0) {
error_setg_errno(errp, -ret,
"ERROR: Could not read data file name");
return ret;
}
#ifdef DEBUG_EXT
printf("Qcow2: Got external data file %s\n", s->image_data_file);
#endif
break;
}
default:
/* unknown magic - save it in case we need to rewrite the header */
/* If you add a new feature, make sure to also update the fast
* path of qcow2_make_empty() to deal with it. */
{
Qcow2UnknownHeaderExtension *uext;
uext = g_malloc0(sizeof(*uext) + ext.len);
uext->magic = ext.magic;
uext->len = ext.len;
QLIST_INSERT_HEAD(&s->unknown_header_ext, uext, next);
ret = bdrv_pread(bs->file, offset , uext->data, uext->len);
if (ret < 0) {
error_setg_errno(errp, -ret, "ERROR: unknown extension: "
"Could not read data");
return ret;
}
}
break;
}
offset += ((ext.len + 7) & ~7);
}
return 0;
}
static void cleanup_unknown_header_ext(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
Qcow2UnknownHeaderExtension *uext, *next;
QLIST_FOREACH_SAFE(uext, &s->unknown_header_ext, next, next) {
QLIST_REMOVE(uext, next);
g_free(uext);
}
}
static void report_unsupported_feature(Error **errp, Qcow2Feature *table,
uint64_t mask)
{
g_autoptr(GString) features = g_string_sized_new(60);
while (table && table->name[0] != '\0') {
if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) {
if (mask & (1ULL << table->bit)) {
if (features->len > 0) {
g_string_append(features, ", ");
}
g_string_append_printf(features, "%.46s", table->name);
mask &= ~(1ULL << table->bit);
}
}
table++;
}
if (mask) {
if (features->len > 0) {
g_string_append(features, ", ");
}
g_string_append_printf(features,
"Unknown incompatible feature: %" PRIx64, mask);
}
error_setg(errp, "Unsupported qcow2 feature(s): %s", features->str);
}
/*
* Sets the dirty bit and flushes afterwards if necessary.
*
* The incompatible_features bit is only set if the image file header was
* updated successfully. Therefore it is not required to check the return
* value of this function.
*/
int qcow2_mark_dirty(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
uint64_t val;
int ret;
assert(s->qcow_version >= 3);
if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
return 0; /* already dirty */
}
val = cpu_to_be64(s->incompatible_features | QCOW2_INCOMPAT_DIRTY);
ret = bdrv_pwrite(bs->file, offsetof(QCowHeader, incompatible_features),
&val, sizeof(val));
if (ret < 0) {
return ret;
}
ret = bdrv_flush(bs->file->bs);
if (ret < 0) {
return ret;
}
/* Only treat image as dirty if the header was updated successfully */
s->incompatible_features |= QCOW2_INCOMPAT_DIRTY;
return 0;
}
/*
* Clears the dirty bit and flushes before if necessary. Only call this
* function when there are no pending requests, it does not guard against
* concurrent requests dirtying the image.
*/
static int qcow2_mark_clean(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
int ret;
s->incompatible_features &= ~QCOW2_INCOMPAT_DIRTY;
ret = qcow2_flush_caches(bs);
if (ret < 0) {
return ret;
}
return qcow2_update_header(bs);
}
return 0;
}
/*
* Marks the image as corrupt.
*/
int qcow2_mark_corrupt(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
s->incompatible_features |= QCOW2_INCOMPAT_CORRUPT;
return qcow2_update_header(bs);
}
/*
* Marks the image as consistent, i.e., unsets the corrupt bit, and flushes
* before if necessary.
*/
int qcow2_mark_consistent(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
int ret = qcow2_flush_caches(bs);
if (ret < 0) {
return ret;
}
s->incompatible_features &= ~QCOW2_INCOMPAT_CORRUPT;
return qcow2_update_header(bs);
}
return 0;
}
static void qcow2_add_check_result(BdrvCheckResult *out,
const BdrvCheckResult *src,
bool set_allocation_info)
{
out->corruptions += src->corruptions;
out->leaks += src->leaks;
out->check_errors += src->check_errors;
out->corruptions_fixed += src->corruptions_fixed;
out->leaks_fixed += src->leaks_fixed;
if (set_allocation_info) {
out->image_end_offset = src->image_end_offset;
out->bfi = src->bfi;
}
}
static int coroutine_fn qcow2_co_check_locked(BlockDriverState *bs,
BdrvCheckResult *result,
BdrvCheckMode fix)
{
BdrvCheckResult snapshot_res = {};
BdrvCheckResult refcount_res = {};
int ret;
memset(result, 0, sizeof(*result));
ret = qcow2_check_read_snapshot_table(bs, &snapshot_res, fix);
if (ret < 0) {
qcow2_add_check_result(result, &snapshot_res, false);
return ret;
}
ret = qcow2_check_refcounts(bs, &refcount_res, fix);
qcow2_add_check_result(result, &refcount_res, true);
if (ret < 0) {
qcow2_add_check_result(result, &snapshot_res, false);
return ret;
}
ret = qcow2_check_fix_snapshot_table(bs, &snapshot_res, fix);
qcow2_add_check_result(result, &snapshot_res, false);
if (ret < 0) {
return ret;
}
if (fix && result->check_errors == 0 && result->corruptions == 0) {
ret = qcow2_mark_clean(bs);
if (ret < 0) {
return ret;
}
return qcow2_mark_consistent(bs);
}
return ret;
}
static int coroutine_fn qcow2_co_check(BlockDriverState *bs,
BdrvCheckResult *result,
BdrvCheckMode fix)
{
BDRVQcow2State *s = bs->opaque;
int ret;
qemu_co_mutex_lock(&s->lock);
ret = qcow2_co_check_locked(bs, result, fix);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
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)
{
BDRVQcow2State *s = bs->opaque;
if (entries > max_size_bytes / entry_len) {
error_setg(errp, "%s too large", table_name);
return -EFBIG;
}
/* Use signed INT64_MAX as the maximum even for uint64_t header fields,
* because values will be passed to qemu functions taking int64_t. */
if ((INT64_MAX - entries * entry_len < offset) ||
(offset_into_cluster(s, offset) != 0)) {
error_setg(errp, "%s offset invalid", table_name);
return -EINVAL;
}
return 0;
}
static const char *const mutable_opts[] = {
QCOW2_OPT_LAZY_REFCOUNTS,
QCOW2_OPT_DISCARD_REQUEST,
QCOW2_OPT_DISCARD_SNAPSHOT,
QCOW2_OPT_DISCARD_OTHER,
QCOW2_OPT_OVERLAP,
QCOW2_OPT_OVERLAP_TEMPLATE,
QCOW2_OPT_OVERLAP_MAIN_HEADER,
QCOW2_OPT_OVERLAP_ACTIVE_L1,
QCOW2_OPT_OVERLAP_ACTIVE_L2,
QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
QCOW2_OPT_OVERLAP_INACTIVE_L1,
QCOW2_OPT_OVERLAP_INACTIVE_L2,
QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
QCOW2_OPT_CACHE_SIZE,
QCOW2_OPT_L2_CACHE_SIZE,
QCOW2_OPT_L2_CACHE_ENTRY_SIZE,
QCOW2_OPT_REFCOUNT_CACHE_SIZE,
QCOW2_OPT_CACHE_CLEAN_INTERVAL,
NULL
};
static QemuOptsList qcow2_runtime_opts = {
.name = "qcow2",
.head = QTAILQ_HEAD_INITIALIZER(qcow2_runtime_opts.head),
.desc = {
{
.name = QCOW2_OPT_LAZY_REFCOUNTS,
.type = QEMU_OPT_BOOL,
.help = "Postpone refcount updates",
},
{
.name = QCOW2_OPT_DISCARD_REQUEST,
.type = QEMU_OPT_BOOL,
.help = "Pass guest discard requests to the layer below",
},
{
.name = QCOW2_OPT_DISCARD_SNAPSHOT,
.type = QEMU_OPT_BOOL,
.help = "Generate discard requests when snapshot related space "
"is freed",
},
{
.name = QCOW2_OPT_DISCARD_OTHER,
.type = QEMU_OPT_BOOL,
.help = "Generate discard requests when other clusters are freed",
},
{
.name = QCOW2_OPT_OVERLAP,
.type = QEMU_OPT_STRING,
.help = "Selects which overlap checks to perform from a range of "
"templates (none, constant, cached, all)",
},
{
.name = QCOW2_OPT_OVERLAP_TEMPLATE,
.type = QEMU_OPT_STRING,
.help = "Selects which overlap checks to perform from a range of "
"templates (none, constant, cached, all)",
},
{
.name = QCOW2_OPT_OVERLAP_MAIN_HEADER,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into the main qcow2 header",
},
{
.name = QCOW2_OPT_OVERLAP_ACTIVE_L1,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into the active L1 table",
},
{
.name = QCOW2_OPT_OVERLAP_ACTIVE_L2,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into an active L2 table",
},
{
.name = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into the refcount table",
},
{
.name = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into a refcount block",
},
{
.name = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into the snapshot table",
},
{
.name = QCOW2_OPT_OVERLAP_INACTIVE_L1,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into an inactive L1 table",
},
{
.name = QCOW2_OPT_OVERLAP_INACTIVE_L2,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into an inactive L2 table",
},
{
.name = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
.type = QEMU_OPT_BOOL,
.help = "Check for unintended writes into the bitmap directory",
},
{
.name = QCOW2_OPT_CACHE_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Maximum combined metadata (L2 tables and refcount blocks) "
"cache size",
},
{
.name = QCOW2_OPT_L2_CACHE_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Maximum L2 table cache size",
},
{
.name = QCOW2_OPT_L2_CACHE_ENTRY_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Size of each entry in the L2 cache",
},
{
.name = QCOW2_OPT_REFCOUNT_CACHE_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Maximum refcount block cache size",
},
{
.name = QCOW2_OPT_CACHE_CLEAN_INTERVAL,
.type = QEMU_OPT_NUMBER,
.help = "Clean unused cache entries after this time (in seconds)",
},
BLOCK_CRYPTO_OPT_DEF_KEY_SECRET("encrypt.",
"ID of secret providing qcow2 AES key or LUKS passphrase"),
{ /* end of list */ }
},
};
static const char *overlap_bool_option_names[QCOW2_OL_MAX_BITNR] = {
[QCOW2_OL_MAIN_HEADER_BITNR] = QCOW2_OPT_OVERLAP_MAIN_HEADER,
[QCOW2_OL_ACTIVE_L1_BITNR] = QCOW2_OPT_OVERLAP_ACTIVE_L1,
[QCOW2_OL_ACTIVE_L2_BITNR] = QCOW2_OPT_OVERLAP_ACTIVE_L2,
[QCOW2_OL_REFCOUNT_TABLE_BITNR] = QCOW2_OPT_OVERLAP_REFCOUNT_TABLE,
[QCOW2_OL_REFCOUNT_BLOCK_BITNR] = QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK,
[QCOW2_OL_SNAPSHOT_TABLE_BITNR] = QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE,
[QCOW2_OL_INACTIVE_L1_BITNR] = QCOW2_OPT_OVERLAP_INACTIVE_L1,
[QCOW2_OL_INACTIVE_L2_BITNR] = QCOW2_OPT_OVERLAP_INACTIVE_L2,
[QCOW2_OL_BITMAP_DIRECTORY_BITNR] = QCOW2_OPT_OVERLAP_BITMAP_DIRECTORY,
};
static void cache_clean_timer_cb(void *opaque)
{
BlockDriverState *bs = opaque;
BDRVQcow2State *s = bs->opaque;
qcow2_cache_clean_unused(s->l2_table_cache);
qcow2_cache_clean_unused(s->refcount_block_cache);
timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
(int64_t) s->cache_clean_interval * 1000);
}
static void cache_clean_timer_init(BlockDriverState *bs, AioContext *context)
{
BDRVQcow2State *s = bs->opaque;
if (s->cache_clean_interval > 0) {
s->cache_clean_timer =
aio_timer_new_with_attrs(context, QEMU_CLOCK_VIRTUAL,
SCALE_MS, QEMU_TIMER_ATTR_EXTERNAL,
cache_clean_timer_cb, bs);
timer_mod(s->cache_clean_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
(int64_t) s->cache_clean_interval * 1000);
}
}
static void cache_clean_timer_del(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
if (s->cache_clean_timer) {
timer_free(s->cache_clean_timer);
s->cache_clean_timer = NULL;
}
}
static void qcow2_detach_aio_context(BlockDriverState *bs)
{
cache_clean_timer_del(bs);
}
static void qcow2_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
cache_clean_timer_init(bs, new_context);
}
static bool read_cache_sizes(BlockDriverState *bs, QemuOpts *opts,
uint64_t *l2_cache_size,
uint64_t *l2_cache_entry_size,
uint64_t *refcount_cache_size, Error **errp)
{
BDRVQcow2State *s = bs->opaque;
uint64_t combined_cache_size, l2_cache_max_setting;
bool l2_cache_size_set, refcount_cache_size_set, combined_cache_size_set;
bool l2_cache_entry_size_set;
int min_refcount_cache = MIN_REFCOUNT_CACHE_SIZE * s->cluster_size;
uint64_t virtual_disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
uint64_t max_l2_entries = DIV_ROUND_UP(virtual_disk_size, s->cluster_size);
/* An L2 table is always one cluster in size so the max cache size
* should be a multiple of the cluster size. */
uint64_t max_l2_cache = ROUND_UP(max_l2_entries * l2_entry_size(s),
s->cluster_size);
combined_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_CACHE_SIZE);
l2_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_SIZE);
refcount_cache_size_set = qemu_opt_get(opts, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
l2_cache_entry_size_set = qemu_opt_get(opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE);
combined_cache_size = qemu_opt_get_size(opts, QCOW2_OPT_CACHE_SIZE, 0);
l2_cache_max_setting = qemu_opt_get_size(opts, QCOW2_OPT_L2_CACHE_SIZE,
DEFAULT_L2_CACHE_MAX_SIZE);
*refcount_cache_size = qemu_opt_get_size(opts,
QCOW2_OPT_REFCOUNT_CACHE_SIZE, 0);
*l2_cache_entry_size = qemu_opt_get_size(
opts, QCOW2_OPT_L2_CACHE_ENTRY_SIZE, s->cluster_size);
*l2_cache_size = MIN(max_l2_cache, l2_cache_max_setting);
if (combined_cache_size_set) {
if (l2_cache_size_set && refcount_cache_size_set) {
error_setg(errp, QCOW2_OPT_CACHE_SIZE ", " QCOW2_OPT_L2_CACHE_SIZE
" and " QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not be set "
"at the same time");
return false;
} else if (l2_cache_size_set &&
(l2_cache_max_setting > combined_cache_size)) {
error_setg(errp, QCOW2_OPT_L2_CACHE_SIZE " may not exceed "
QCOW2_OPT_CACHE_SIZE);
return false;
} else if (*refcount_cache_size > combined_cache_size) {
error_setg(errp, QCOW2_OPT_REFCOUNT_CACHE_SIZE " may not exceed "
QCOW2_OPT_CACHE_SIZE);
return false;
}
if (l2_cache_size_set) {
*refcount_cache_size = combined_cache_size - *l2_cache_size;
} else if (refcount_cache_size_set) {
*l2_cache_size = combined_cache_size - *refcount_cache_size;
} else {
/* Assign as much memory as possible to the L2 cache, and
* use the remainder for the refcount cache */
if (combined_cache_size >= max_l2_cache + min_refcount_cache) {
*l2_cache_size = max_l2_cache;
*refcount_cache_size = combined_cache_size - *l2_cache_size;
} else {
*refcount_cache_size =
MIN(combined_cache_size, min_refcount_cache);
*l2_cache_size = combined_cache_size - *refcount_cache_size;
}
}
}
/*
* If the L2 cache is not enough to cover the whole disk then
* default to 4KB entries. Smaller entries reduce the cost of
* loads and evictions and increase I/O performance.
*/
if (*l2_cache_size < max_l2_cache && !l2_cache_entry_size_set) {
*l2_cache_entry_size = MIN(s->cluster_size, 4096);
}
/* l2_cache_size and refcount_cache_size are ensured to have at least
* their minimum values in qcow2_update_options_prepare() */
if (*l2_cache_entry_size < (1 << MIN_CLUSTER_BITS) ||
*l2_cache_entry_size > s->cluster_size ||
!is_power_of_2(*l2_cache_entry_size)) {
error_setg(errp, "L2 cache entry size must be a power of two "
"between %d and the cluster size (%d)",
1 << MIN_CLUSTER_BITS, s->cluster_size);
return false;
}
return true;
}
typedef struct Qcow2ReopenState {
Qcow2Cache *l2_table_cache;
Qcow2Cache *refcount_block_cache;
int l2_slice_size; /* Number of entries in a slice of the L2 table */
bool use_lazy_refcounts;
int overlap_check;
bool discard_passthrough[QCOW2_DISCARD_MAX];
uint64_t cache_clean_interval;
QCryptoBlockOpenOptions *crypto_opts; /* Disk encryption runtime options */
} Qcow2ReopenState;
static int qcow2_update_options_prepare(BlockDriverState *bs,
Qcow2ReopenState *r,
QDict *options, int flags,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
QemuOpts *opts = NULL;
const char *opt_overlap_check, *opt_overlap_check_template;
int overlap_check_template = 0;
uint64_t l2_cache_size, l2_cache_entry_size, refcount_cache_size;
int i;
const char *encryptfmt;
QDict *encryptopts = NULL;
int ret;
qdict_extract_subqdict(options, &encryptopts, "encrypt.");
encryptfmt = qdict_get_try_str(encryptopts, "format");
opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort);
if (!qemu_opts_absorb_qdict(opts, options, errp)) {
ret = -EINVAL;
goto fail;
}
/* get L2 table/refcount block cache size from command line options */
if (!read_cache_sizes(bs, opts, &l2_cache_size, &l2_cache_entry_size,
&refcount_cache_size, errp)) {
ret = -EINVAL;
goto fail;
}
l2_cache_size /= l2_cache_entry_size;
if (l2_cache_size < MIN_L2_CACHE_SIZE) {
l2_cache_size = MIN_L2_CACHE_SIZE;
}
if (l2_cache_size > INT_MAX) {
error_setg(errp, "L2 cache size too big");
ret = -EINVAL;
goto fail;
}
refcount_cache_size /= s->cluster_size;
if (refcount_cache_size < MIN_REFCOUNT_CACHE_SIZE) {
refcount_cache_size = MIN_REFCOUNT_CACHE_SIZE;
}
if (refcount_cache_size > INT_MAX) {
error_setg(errp, "Refcount cache size too big");
ret = -EINVAL;
goto fail;
}
/* alloc new L2 table/refcount block cache, flush old one */
if (s->l2_table_cache) {
ret = qcow2_cache_flush(bs, s->l2_table_cache);
if (ret) {
error_setg_errno(errp, -ret, "Failed to flush the L2 table cache");
goto fail;
}
}
if (s->refcount_block_cache) {
ret = qcow2_cache_flush(bs, s->refcount_block_cache);
if (ret) {
error_setg_errno(errp, -ret,
"Failed to flush the refcount block cache");
goto fail;
}
}
r->l2_slice_size = l2_cache_entry_size / l2_entry_size(s);
r->l2_table_cache = qcow2_cache_create(bs, l2_cache_size,
l2_cache_entry_size);
r->refcount_block_cache = qcow2_cache_create(bs, refcount_cache_size,
s->cluster_size);
if (r->l2_table_cache == NULL || r->refcount_block_cache == NULL) {
error_setg(errp, "Could not allocate metadata caches");
ret = -ENOMEM;
goto fail;
}
/* New interval for cache cleanup timer */
r->cache_clean_interval =
qemu_opt_get_number(opts, QCOW2_OPT_CACHE_CLEAN_INTERVAL,
DEFAULT_CACHE_CLEAN_INTERVAL);
#ifndef CONFIG_LINUX
if (r->cache_clean_interval != 0) {
error_setg(errp, QCOW2_OPT_CACHE_CLEAN_INTERVAL
" not supported on this host");
ret = -EINVAL;
goto fail;
}
#endif
if (r->cache_clean_interval > UINT_MAX) {
error_setg(errp, "Cache clean interval too big");
ret = -EINVAL;
goto fail;
}
/* lazy-refcounts; flush if going from enabled to disabled */
r->use_lazy_refcounts = qemu_opt_get_bool(opts, QCOW2_OPT_LAZY_REFCOUNTS,
(s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS));
if (r->use_lazy_refcounts && s->qcow_version < 3) {
error_setg(errp, "Lazy refcounts require a qcow2 image with at least "
"qemu 1.1 compatibility level");
ret = -EINVAL;
goto fail;
}
if (s->use_lazy_refcounts && !r->use_lazy_refcounts) {
ret = qcow2_mark_clean(bs);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to disable lazy refcounts");
goto fail;
}
}
/* Overlap check options */
opt_overlap_check = qemu_opt_get(opts, QCOW2_OPT_OVERLAP);
opt_overlap_check_template = qemu_opt_get(opts, QCOW2_OPT_OVERLAP_TEMPLATE);
if (opt_overlap_check_template && opt_overlap_check &&
strcmp(opt_overlap_check_template, opt_overlap_check))
{
error_setg(errp, "Conflicting values for qcow2 options '"
QCOW2_OPT_OVERLAP "' ('%s') and '" QCOW2_OPT_OVERLAP_TEMPLATE
"' ('%s')", opt_overlap_check, opt_overlap_check_template);
ret = -EINVAL;
goto fail;
}
if (!opt_overlap_check) {
opt_overlap_check = opt_overlap_check_template ?: "cached";
}
if (!strcmp(opt_overlap_check, "none")) {
overlap_check_template = 0;
} else if (!strcmp(opt_overlap_check, "constant")) {
overlap_check_template = QCOW2_OL_CONSTANT;
} else if (!strcmp(opt_overlap_check, "cached")) {
overlap_check_template = QCOW2_OL_CACHED;
} else if (!strcmp(opt_overlap_check, "all")) {
overlap_check_template = QCOW2_OL_ALL;
} else {
error_setg(errp, "Unsupported value '%s' for qcow2 option "
"'overlap-check'. Allowed are any of the following: "
"none, constant, cached, all", opt_overlap_check);
ret = -EINVAL;
goto fail;
}
r->overlap_check = 0;
for (i = 0; i < QCOW2_OL_MAX_BITNR; i++) {
/* overlap-check defines a template bitmask, but every flag may be
* overwritten through the associated boolean option */
r->overlap_check |=
qemu_opt_get_bool(opts, overlap_bool_option_names[i],
overlap_check_template & (1 << i)) << i;
}
r->discard_passthrough[QCOW2_DISCARD_NEVER] = false;
r->discard_passthrough[QCOW2_DISCARD_ALWAYS] = true;
r->discard_passthrough[QCOW2_DISCARD_REQUEST] =
qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_REQUEST,
flags & BDRV_O_UNMAP);
r->discard_passthrough[QCOW2_DISCARD_SNAPSHOT] =
qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_SNAPSHOT, true);
r->discard_passthrough[QCOW2_DISCARD_OTHER] =
qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_OTHER, false);
switch (s->crypt_method_header) {
case QCOW_CRYPT_NONE:
if (encryptfmt) {
error_setg(errp, "No encryption in image header, but options "
"specified format '%s'", encryptfmt);
ret = -EINVAL;
goto fail;
}
break;
case QCOW_CRYPT_AES:
if (encryptfmt && !g_str_equal(encryptfmt, "aes")) {
error_setg(errp,
"Header reported 'aes' encryption format but "
"options specify '%s'", encryptfmt);
ret = -EINVAL;
goto fail;
}
qdict_put_str(encryptopts, "format", "qcow");
r->crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
if (!r->crypto_opts) {
ret = -EINVAL;
goto fail;
}
break;
case QCOW_CRYPT_LUKS:
if (encryptfmt && !g_str_equal(encryptfmt, "luks")) {
error_setg(errp,
"Header reported 'luks' encryption format but "
"options specify '%s'", encryptfmt);
ret = -EINVAL;
goto fail;
}
qdict_put_str(encryptopts, "format", "luks");
r->crypto_opts = block_crypto_open_opts_init(encryptopts, errp);
if (!r->crypto_opts) {
ret = -EINVAL;
goto fail;
}
break;
default:
error_setg(errp, "Unsupported encryption method %d",
s->crypt_method_header);
ret = -EINVAL;
goto fail;
}
ret = 0;
fail:
qobject_unref(encryptopts);
qemu_opts_del(opts);
opts = NULL;
return ret;
}
static void qcow2_update_options_commit(BlockDriverState *bs,
Qcow2ReopenState *r)
{
BDRVQcow2State *s = bs->opaque;
int i;
if (s->l2_table_cache) {
qcow2_cache_destroy(s->l2_table_cache);
}
if (s->refcount_block_cache) {
qcow2_cache_destroy(s->refcount_block_cache);
}
s->l2_table_cache = r->l2_table_cache;
s->refcount_block_cache = r->refcount_block_cache;
s->l2_slice_size = r->l2_slice_size;
s->overlap_check = r->overlap_check;
s->use_lazy_refcounts = r->use_lazy_refcounts;
for (i = 0; i < QCOW2_DISCARD_MAX; i++) {
s->discard_passthrough[i] = r->discard_passthrough[i];
}
if (s->cache_clean_interval != r->cache_clean_interval) {
cache_clean_timer_del(bs);
s->cache_clean_interval = r->cache_clean_interval;
cache_clean_timer_init(bs, bdrv_get_aio_context(bs));
}
qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
s->crypto_opts = r->crypto_opts;
}
static void qcow2_update_options_abort(BlockDriverState *bs,
Qcow2ReopenState *r)
{
if (r->l2_table_cache) {
qcow2_cache_destroy(r->l2_table_cache);
}
if (r->refcount_block_cache) {
qcow2_cache_destroy(r->refcount_block_cache);
}
qapi_free_QCryptoBlockOpenOptions(r->crypto_opts);
}
static int qcow2_update_options(BlockDriverState *bs, QDict *options,
int flags, Error **errp)
{
Qcow2ReopenState r = {};
int ret;
ret = qcow2_update_options_prepare(bs, &r, options, flags, errp);
if (ret >= 0) {
qcow2_update_options_commit(bs, &r);
} else {
qcow2_update_options_abort(bs, &r);
}
return ret;
}
static int validate_compression_type(BDRVQcow2State *s, Error **errp)
{
switch (s->compression_type) {
case QCOW2_COMPRESSION_TYPE_ZLIB:
#ifdef CONFIG_ZSTD
case QCOW2_COMPRESSION_TYPE_ZSTD:
#endif
break;
default:
error_setg(errp, "qcow2: unknown compression type: %u",
s->compression_type);
return -ENOTSUP;
}
/*
* if the compression type differs from QCOW2_COMPRESSION_TYPE_ZLIB
* the incompatible feature flag must be set
*/
if (s->compression_type == QCOW2_COMPRESSION_TYPE_ZLIB) {
if (s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION) {
error_setg(errp, "qcow2: Compression type incompatible feature "
"bit must not be set");
return -EINVAL;
}
} else {
if (!(s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION)) {
error_setg(errp, "qcow2: Compression type incompatible feature "
"bit must be set");
return -EINVAL;
}
}
return 0;
}
/* Called with s->lock held. */
static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
int flags, Error **errp)
{
ERRP_GUARD();
BDRVQcow2State *s = bs->opaque;
unsigned int len, i;
int ret = 0;
QCowHeader header;
uint64_t ext_end;
uint64_t l1_vm_state_index;
bool update_header = false;
ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read qcow2 header");
goto fail;
}
header.magic = be32_to_cpu(header.magic);
header.version = be32_to_cpu(header.version);
header.backing_file_offset = be64_to_cpu(header.backing_file_offset);
header.backing_file_size = be32_to_cpu(header.backing_file_size);
header.size = be64_to_cpu(header.size);
header.cluster_bits = be32_to_cpu(header.cluster_bits);
header.crypt_method = be32_to_cpu(header.crypt_method);
header.l1_table_offset = be64_to_cpu(header.l1_table_offset);
header.l1_size = be32_to_cpu(header.l1_size);
header.refcount_table_offset = be64_to_cpu(header.refcount_table_offset);
header.refcount_table_clusters =
be32_to_cpu(header.refcount_table_clusters);
header.snapshots_offset = be64_to_cpu(header.snapshots_offset);
header.nb_snapshots = be32_to_cpu(header.nb_snapshots);
if (header.magic != QCOW_MAGIC) {
error_setg(errp, "Image is not in qcow2 format");
ret = -EINVAL;
goto fail;
}
if (header.version < 2 || header.version > 3) {
error_setg(errp, "Unsupported qcow2 version %" PRIu32, header.version);
ret = -ENOTSUP;
goto fail;
}
s->qcow_version = header.version;
/* Initialise cluster size */
if (header.cluster_bits < MIN_CLUSTER_BITS ||
header.cluster_bits > MAX_CLUSTER_BITS) {
error_setg(errp, "Unsupported cluster size: 2^%" PRIu32,
header.cluster_bits);
ret = -EINVAL;
goto fail;
}
s->cluster_bits = header.cluster_bits;
s->cluster_size = 1 << s->cluster_bits;
/* Initialise version 3 header fields */
if (header.version == 2) {
header.incompatible_features = 0;
header.compatible_features = 0;
header.autoclear_features = 0;
header.refcount_order = 4;
header.header_length = 72;
} else {
header.incompatible_features =
be64_to_cpu(header.incompatible_features);
header.compatible_features = be64_to_cpu(header.compatible_features);
header.autoclear_features = be64_to_cpu(header.autoclear_features);
header.refcount_order = be32_to_cpu(header.refcount_order);
header.header_length = be32_to_cpu(header.header_length);
if (header.header_length < 104) {
error_setg(errp, "qcow2 header too short");
ret = -EINVAL;
goto fail;
}
}
if (header.header_length > s->cluster_size) {
error_setg(errp, "qcow2 header exceeds cluster size");
ret = -EINVAL;
goto fail;
}
if (header.header_length > sizeof(header)) {
s->unknown_header_fields_size = header.header_length - sizeof(header);
s->unknown_header_fields = g_malloc(s->unknown_header_fields_size);
ret = bdrv_pread(bs->file, sizeof(header), s->unknown_header_fields,
s->unknown_header_fields_size);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read unknown qcow2 header "
"fields");
goto fail;
}
}
if (header.backing_file_offset > s->cluster_size) {
error_setg(errp, "Invalid backing file offset");
ret = -EINVAL;
goto fail;
}
if (header.backing_file_offset) {
ext_end = header.backing_file_offset;
} else {
ext_end = 1 << header.cluster_bits;
}
/* Handle feature bits */
s->incompatible_features = header.incompatible_features;
s->compatible_features = header.compatible_features;
s->autoclear_features = header.autoclear_features;
/*
* Handle compression type
* Older qcow2 images don't contain the compression type header.
* Distinguish them by the header length and use
* the only valid (default) compression type in that case
*/
if (header.header_length > offsetof(QCowHeader, compression_type)) {
s->compression_type = header.compression_type;
} else {
s->compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
}
ret = validate_compression_type(s, errp);
if (ret) {
goto fail;
}
if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) {
void *feature_table = NULL;
qcow2_read_extensions(bs, header.header_length, ext_end,
&feature_table, flags, NULL, NULL);
report_unsupported_feature(errp, feature_table,
s->incompatible_features &
~QCOW2_INCOMPAT_MASK);
ret = -ENOTSUP;
g_free(feature_table);
goto fail;
}
if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
/* Corrupt images may not be written to unless they are being repaired
*/
if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) {
error_setg(errp, "qcow2: Image is corrupt; cannot be opened "
"read/write");
ret = -EACCES;
goto fail;
}
}
s->subclusters_per_cluster =
has_subclusters(s) ? QCOW_EXTL2_SUBCLUSTERS_PER_CLUSTER : 1;
s->subcluster_size = s->cluster_size / s->subclusters_per_cluster;
s->subcluster_bits = ctz32(s->subcluster_size);
if (s->subcluster_size < (1 << MIN_CLUSTER_BITS)) {
error_setg(errp, "Unsupported subcluster size: %d", s->subcluster_size);
ret = -EINVAL;
goto fail;
}
/* Check support for various header values */
if (header.refcount_order > 6) {
error_setg(errp, "Reference count entry width too large; may not "
"exceed 64 bits");
ret = -EINVAL;
goto fail;
}
s->refcount_order = header.refcount_order;
s->refcount_bits = 1 << s->refcount_order;
s->refcount_max = UINT64_C(1) << (s->refcount_bits - 1);
s->refcount_max += s->refcount_max - 1;
s->crypt_method_header = header.crypt_method;
if (s->crypt_method_header) {
if (bdrv_uses_whitelist() &&
s->crypt_method_header == QCOW_CRYPT_AES) {
error_setg(errp,
"Use of AES-CBC encrypted qcow2 images is no longer "
"supported in system emulators");
error_append_hint(errp,
"You can use 'qemu-img convert' to convert your "
"image to an alternative supported format, such "
"as unencrypted qcow2, or raw with the LUKS "
"format instead.\n");
ret = -ENOSYS;
goto fail;
}
if (s->crypt_method_header == QCOW_CRYPT_AES) {
s->crypt_physical_offset = false;
} else {
/* Assuming LUKS and any future crypt methods we
* add will all use physical offsets, due to the
* fact that the alternative is insecure... */
s->crypt_physical_offset = true;
}
bs->encrypted = true;
}
s->l2_bits = s->cluster_bits - ctz32(l2_entry_size(s));
s->l2_size = 1 << s->l2_bits;
/* 2^(s->refcount_order - 3) is the refcount width in bytes */
s->refcount_block_bits = s->cluster_bits - (s->refcount_order - 3);
s->refcount_block_size = 1 << s->refcount_block_bits;
bs->total_sectors = header.size / BDRV_SECTOR_SIZE;
s->csize_shift = (62 - (s->cluster_bits - 8));
s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
s->refcount_table_offset = header.refcount_table_offset;
s->refcount_table_size =
header.refcount_table_clusters << (s->cluster_bits - 3);
if (header.refcount_table_clusters == 0 && !(flags & BDRV_O_CHECK)) {
error_setg(errp, "Image does not contain a reference count table");
ret = -EINVAL;
goto fail;
}
ret = qcow2_validate_table(bs, s->refcount_table_offset,
header.refcount_table_clusters,
s->cluster_size, QCOW_MAX_REFTABLE_SIZE,
"Reference count table", errp);
if (ret < 0) {
goto fail;
}
if (!(flags & BDRV_O_CHECK)) {
/*
* The total size in bytes of the snapshot table is checked in
* qcow2_read_snapshots() because the size of each snapshot is
* variable and we don't know it yet.
* Here we only check the offset and number of snapshots.
*/
ret = qcow2_validate_table(bs, header.snapshots_offset,
header.nb_snapshots,
sizeof(QCowSnapshotHeader),
sizeof(QCowSnapshotHeader) *
QCOW_MAX_SNAPSHOTS,
"Snapshot table", errp);
if (ret < 0) {
goto fail;
}
}
/* read the level 1 table */
ret = qcow2_validate_table(bs, header.l1_table_offset,
header.l1_size, L1E_SIZE,
QCOW_MAX_L1_SIZE, "Active L1 table", errp);
if (ret < 0) {
goto fail;
}
s->l1_size = header.l1_size;
s->l1_table_offset = header.l1_table_offset;
l1_vm_state_index = size_to_l1(s, header.size);
if (l1_vm_state_index > INT_MAX) {
error_setg(errp, "Image is too big");
ret = -EFBIG;
goto fail;
}
s->l1_vm_state_index = l1_vm_state_index;
/* the L1 table must contain at least enough entries to put
header.size bytes */
if (s->l1_size < s->l1_vm_state_index) {
error_setg(errp, "L1 table is too small");
ret = -EINVAL;
goto fail;
}
if (s->l1_size > 0) {
s->l1_table = qemu_try_blockalign(bs->file->bs, s->l1_size * L1E_SIZE);
if (s->l1_table == NULL) {
error_setg(errp, "Could not allocate L1 table");
ret = -ENOMEM;
goto fail;
}
ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table,
s->l1_size * L1E_SIZE);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read L1 table");
goto fail;
}
for(i = 0;i < s->l1_size; i++) {
s->l1_table[i] = be64_to_cpu(s->l1_table[i]);
}
}
/* Parse driver-specific options */
ret = qcow2_update_options(bs, options, flags, errp);
if (ret < 0) {
goto fail;
}
s->flags = flags;
ret = qcow2_refcount_init(bs);
if (ret != 0) {
error_setg_errno(errp, -ret, "Could not initialize refcount handling");
goto fail;
}
QLIST_INIT(&s->cluster_allocs);
QTAILQ_INIT(&s->discards);
/* read qcow2 extensions */
if (qcow2_read_extensions(bs, header.header_length, ext_end, NULL,
flags, &update_header, errp)) {
ret = -EINVAL;
goto fail;
}
/* Open external data file */
s->data_file = bdrv_open_child(NULL, options, "data-file", bs,
&child_of_bds, BDRV_CHILD_DATA,
true, errp);
if (*errp) {
ret = -EINVAL;
goto fail;
}
if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) {
if (!s->data_file && s->image_data_file) {
s->data_file = bdrv_open_child(s->image_data_file, options,
"data-file", bs, &child_of_bds,
BDRV_CHILD_DATA, false, errp);
if (!s->data_file) {
ret = -EINVAL;
goto fail;
}
}
if (!s->data_file) {
error_setg(errp, "'data-file' is required for this image");
ret = -EINVAL;
goto fail;
}
/* No data here */
bs->file->role &= ~BDRV_CHILD_DATA;
/* Must succeed because we have given up permissions if anything */
bdrv_child_refresh_perms(bs, bs->file, &error_abort);
} else {
if (s->data_file) {
error_setg(errp, "'data-file' can only be set for images with an "
"external data file");
ret = -EINVAL;
goto fail;
}
s->data_file = bs->file;
if (data_file_is_raw(bs)) {
error_setg(errp, "data-file-raw requires a data file");
ret = -EINVAL;
goto fail;
}
}
/* qcow2_read_extension may have set up the crypto context
* if the crypt method needs a header region, some methods
* don't need header extensions, so must check here
*/
if (s->crypt_method_header && !s->crypto) {
if (s->crypt_method_header == QCOW_CRYPT_AES) {
unsigned int cflags = 0;
if (flags & BDRV_O_NO_IO) {
cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
}
s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
NULL, NULL, cflags,
QCOW2_MAX_THREADS, errp);
if (!s->crypto) {
ret = -EINVAL;
goto fail;
}
} else if (!(flags & BDRV_O_NO_IO)) {
error_setg(errp, "Missing CRYPTO header for crypt method %d",
s->crypt_method_header);
ret = -EINVAL;
goto fail;
}
}
/* read the backing file name */
if (header.backing_file_offset != 0) {
len = header.backing_file_size;
if (len > MIN(1023, s->cluster_size - header.backing_file_offset) ||
len >= sizeof(bs->backing_file)) {
error_setg(errp, "Backing file name too long");
ret = -EINVAL;
goto fail;
}
ret = bdrv_pread(bs->file, header.backing_file_offset,
bs->auto_backing_file, len);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read backing file name");
goto fail;
}
bs->auto_backing_file[len] = '\0';
pstrcpy(bs->backing_file, sizeof(bs->backing_file),
bs->auto_backing_file);
s->image_backing_file = g_strdup(bs->auto_backing_file);
}
/*
* Internal snapshots; skip reading them in check mode, because
* we do not need them then, and we do not want to abort because
* of a broken table.
*/
if (!(flags & BDRV_O_CHECK)) {
s->snapshots_offset = header.snapshots_offset;
s->nb_snapshots = header.nb_snapshots;
ret = qcow2_read_snapshots(bs, errp);
if (ret < 0) {
goto fail;
}
}
/* Clear unknown autoclear feature bits */
update_header |= s->autoclear_features & ~QCOW2_AUTOCLEAR_MASK;
update_header = update_header && bdrv_is_writable(bs);
if (update_header) {
s->autoclear_features &= QCOW2_AUTOCLEAR_MASK;
}
/* == Handle persistent dirty bitmaps ==
*
* We want load dirty bitmaps in three cases:
*
* 1. Normal open of the disk in active mode, not related to invalidation
* after migration.
*
* 2. Invalidation of the target vm after pre-copy phase of migration, if
* bitmaps are _not_ migrating through migration channel, i.e.
* 'dirty-bitmaps' capability is disabled.
*
* 3. Invalidation of source vm after failed or canceled migration.
* This is a very interesting case. There are two possible types of
* bitmaps:
*
* A. Stored on inactivation and removed. They should be loaded from the
* image.
*
* B. Not stored: not-persistent bitmaps and bitmaps, migrated through
* the migration channel (with dirty-bitmaps capability).
*
* On the other hand, there are two possible sub-cases:
*
* 3.1 disk was changed by somebody else while were inactive. In this
* case all in-RAM dirty bitmaps (both persistent and not) are
* definitely invalid. And we don't have any method to determine
* this.
*
* Simple and safe thing is to just drop all the bitmaps of type B on
* inactivation. But in this case we lose bitmaps in valid 4.2 case.
*
* On the other hand, resuming source vm, if disk was already changed
* is a bad thing anyway: not only bitmaps, the whole vm state is
* out of sync with disk.
*
* This means, that user or management tool, who for some reason
* decided to resume source vm, after disk was already changed by
* target vm, should at least drop all dirty bitmaps by hand.
*
* So, we can ignore this case for now, but TODO: "generation"
* extension for qcow2, to determine, that image was changed after
* last inactivation. And if it is changed, we will drop (or at least
* mark as 'invalid' all the bitmaps of type B, both persistent
* and not).
*
* 3.2 disk was _not_ changed while were inactive. Bitmaps may be saved
* to disk ('dirty-bitmaps' capability disabled), or not saved
* ('dirty-bitmaps' capability enabled), but we don't need to care
* of: let's load bitmaps as always: stored bitmaps will be loaded,
* and not stored has flag IN_USE=1 in the image and will be skipped
* on loading.
*
* One remaining possible case when we don't want load bitmaps:
*
* 4. Open disk in inactive mode in target vm (bitmaps are migrating or
* will be loaded on invalidation, no needs try loading them before)
*/
if (!(bdrv_get_flags(bs) & BDRV_O_INACTIVE)) {
/* It's case 1, 2 or 3.2. Or 3.1 which is BUG in management layer. */
bool header_updated;
if (!qcow2_load_dirty_bitmaps(bs, &header_updated, errp)) {
ret = -EINVAL;
goto fail;
}
update_header = update_header && !header_updated;
}
if (update_header) {
ret = qcow2_update_header(bs);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not update qcow2 header");
goto fail;
}
}
bs->supported_zero_flags = header.version >= 3 ?
BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK : 0;
bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
/* Repair image if dirty */
if (!(flags & BDRV_O_CHECK) && bdrv_is_writable(bs) &&
(s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) {
BdrvCheckResult result = {0};
ret = qcow2_co_check_locked(bs, &result,
BDRV_FIX_ERRORS | BDRV_FIX_LEAKS);
if (ret < 0 || result.check_errors) {
if (ret >= 0) {
ret = -EIO;
}
error_setg_errno(errp, -ret, "Could not repair dirty image");
goto fail;
}
}
#ifdef DEBUG_ALLOC
{
BdrvCheckResult result = {0};
qcow2_check_refcounts(bs, &result, 0);
}
#endif
qemu_co_queue_init(&s->thread_task_queue);
return ret;
fail:
g_free(s->image_data_file);
if (has_data_file(bs)) {
bdrv_unref_child(bs, s->data_file);
s->data_file = NULL;
}
g_free(s->unknown_header_fields);
cleanup_unknown_header_ext(bs);
qcow2_free_snapshots(bs);
qcow2_refcount_close(bs);
qemu_vfree(s->l1_table);
/* else pre-write overlap checks in cache_destroy may crash */
s->l1_table = NULL;
cache_clean_timer_del(bs);
if (s->l2_table_cache) {
qcow2_cache_destroy(s->l2_table_cache);
}
if (s->refcount_block_cache) {
qcow2_cache_destroy(s->refcount_block_cache);
}
qcrypto_block_free(s->crypto);
qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
return ret;
}
typedef struct QCow2OpenCo {
BlockDriverState *bs;
QDict *options;
int flags;
Error **errp;
int ret;
} QCow2OpenCo;
static void coroutine_fn qcow2_open_entry(void *opaque)
{
QCow2OpenCo *qoc = opaque;
BDRVQcow2State *s = qoc->bs->opaque;
qemu_co_mutex_lock(&s->lock);
qoc->ret = qcow2_do_open(qoc->bs, qoc->options, qoc->flags, qoc->errp);
qemu_co_mutex_unlock(&s->lock);
}
static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
QCow2OpenCo qoc = {
.bs = bs,
.options = options,
.flags = flags,
.errp = errp,
.ret = -EINPROGRESS
};
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
BDRV_CHILD_IMAGE, false, errp);
if (!bs->file) {
return -EINVAL;
}
/* Initialise locks */
qemu_co_mutex_init(&s->lock);
if (qemu_in_coroutine()) {
/* From bdrv_co_create. */
qcow2_open_entry(&qoc);
} else {
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
qemu_coroutine_enter(qemu_coroutine_create(qcow2_open_entry, &qoc));
BDRV_POLL_WHILE(bs, qoc.ret == -EINPROGRESS);
}
return qoc.ret;
}
static void qcow2_refresh_limits(BlockDriverState *bs, Error **errp)
{
BDRVQcow2State *s = bs->opaque;
if (bs->encrypted) {
/* Encryption works on a sector granularity */
bs->bl.request_alignment = qcrypto_block_get_sector_size(s->crypto);
}
bs->bl.pwrite_zeroes_alignment = s->subcluster_size;
bs->bl.pdiscard_alignment = s->cluster_size;
}
static int qcow2_reopen_prepare(BDRVReopenState *state,
BlockReopenQueue *queue, Error **errp)
{
BDRVQcow2State *s = state->bs->opaque;
Qcow2ReopenState *r;
int ret;
r = g_new0(Qcow2ReopenState, 1);
state->opaque = r;
ret = qcow2_update_options_prepare(state->bs, r, state->options,
state->flags, errp);
if (ret < 0) {
goto fail;
}
/* We need to write out any unwritten data if we reopen read-only. */
if ((state->flags & BDRV_O_RDWR) == 0) {
ret = qcow2_reopen_bitmaps_ro(state->bs, errp);
if (ret < 0) {
goto fail;
}
ret = bdrv_flush(state->bs);
if (ret < 0) {
goto fail;
}
ret = qcow2_mark_clean(state->bs);
if (ret < 0) {
goto fail;
}
}
/*
* Without an external data file, s->data_file points to the same BdrvChild
* as bs->file. It needs to be resynced after reopen because bs->file may
* be changed. We can't use it in the meantime.
*/
if (!has_data_file(state->bs)) {
assert(s->data_file == state->bs->file);
s->data_file = NULL;
}
return 0;
fail:
qcow2_update_options_abort(state->bs, r);
g_free(r);
return ret;
}
static void qcow2_reopen_commit(BDRVReopenState *state)
{
BDRVQcow2State *s = state->bs->opaque;
qcow2_update_options_commit(state->bs, state->opaque);
if (!s->data_file) {
/*
* If we don't have an external data file, s->data_file was cleared by
* qcow2_reopen_prepare() and needs to be updated.
*/
s->data_file = state->bs->file;
}
g_free(state->opaque);
}
static void qcow2_reopen_commit_post(BDRVReopenState *state)
{
if (state->flags & BDRV_O_RDWR) {
Error *local_err = NULL;
if (qcow2_reopen_bitmaps_rw(state->bs, &local_err) < 0) {
/*
* This is not fatal, bitmaps just left read-only, so all following
* writes will fail. User can remove read-only bitmaps to unblock
* writes or retry reopen.
*/
error_reportf_err(local_err,
"%s: Failed to make dirty bitmaps writable: ",
bdrv_get_node_name(state->bs));
}
}
}
static void qcow2_reopen_abort(BDRVReopenState *state)
{
BDRVQcow2State *s = state->bs->opaque;
if (!s->data_file) {
/*
* If we don't have an external data file, s->data_file was cleared by
* qcow2_reopen_prepare() and needs to be restored.
*/
s->data_file = state->bs->file;
}
qcow2_update_options_abort(state->bs, state->opaque);
g_free(state->opaque);
}
static void qcow2_join_options(QDict *options, QDict *old_options)
{
bool has_new_overlap_template =
qdict_haskey(options, QCOW2_OPT_OVERLAP) ||
qdict_haskey(options, QCOW2_OPT_OVERLAP_TEMPLATE);
bool has_new_total_cache_size =
qdict_haskey(options, QCOW2_OPT_CACHE_SIZE);
bool has_all_cache_options;
/* New overlap template overrides all old overlap options */
if (has_new_overlap_template) {
qdict_del(old_options, QCOW2_OPT_OVERLAP);
qdict_del(old_options, QCOW2_OPT_OVERLAP_TEMPLATE);
qdict_del(old_options, QCOW2_OPT_OVERLAP_MAIN_HEADER);
qdict_del(old_options, QCOW2_OPT_OVERLAP_ACTIVE_L1);
qdict_del(old_options, QCOW2_OPT_OVERLAP_ACTIVE_L2);
qdict_del(old_options, QCOW2_OPT_OVERLAP_REFCOUNT_TABLE);
qdict_del(old_options, QCOW2_OPT_OVERLAP_REFCOUNT_BLOCK);
qdict_del(old_options, QCOW2_OPT_OVERLAP_SNAPSHOT_TABLE);
qdict_del(old_options, QCOW2_OPT_OVERLAP_INACTIVE_L1);
qdict_del(old_options, QCOW2_OPT_OVERLAP_INACTIVE_L2);
}
/* New total cache size overrides all old options */
if (qdict_haskey(options, QCOW2_OPT_CACHE_SIZE)) {
qdict_del(old_options, QCOW2_OPT_L2_CACHE_SIZE);
qdict_del(old_options, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
}
qdict_join(options, old_options, false);
/*
* If after merging all cache size options are set, an old total size is
* overwritten. Do keep all options, however, if all three are new. The
* resulting error message is what we want to happen.
*/
has_all_cache_options =
qdict_haskey(options, QCOW2_OPT_CACHE_SIZE) ||
qdict_haskey(options, QCOW2_OPT_L2_CACHE_SIZE) ||
qdict_haskey(options, QCOW2_OPT_REFCOUNT_CACHE_SIZE);
if (has_all_cache_options && !has_new_total_cache_size) {
qdict_del(options, QCOW2_OPT_CACHE_SIZE);
}
}
static int coroutine_fn qcow2_co_block_status(BlockDriverState *bs,
bool want_zero,
int64_t offset, int64_t count,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
BDRVQcow2State *s = bs->opaque;
uint64_t host_offset;
unsigned int bytes;
QCow2SubclusterType type;
int ret, status = 0;
qemu_co_mutex_lock(&s->lock);
if (!s->metadata_preallocation_checked) {
ret = qcow2_detect_metadata_preallocation(bs);
s->metadata_preallocation = (ret == 1);
s->metadata_preallocation_checked = true;
}
bytes = MIN(INT_MAX, count);
ret = qcow2_get_host_offset(bs, offset, &bytes, &host_offset, &type);
qemu_co_mutex_unlock(&s->lock);
if (ret < 0) {
return ret;
}
*pnum = bytes;
if ((type == QCOW2_SUBCLUSTER_NORMAL ||
type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC) && !s->crypto) {
*map = host_offset;
*file = s->data_file->bs;
status |= BDRV_BLOCK_OFFSET_VALID;
}
if (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
type == QCOW2_SUBCLUSTER_ZERO_ALLOC) {
status |= BDRV_BLOCK_ZERO;
} else if (type != QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN &&
type != QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC) {
status |= BDRV_BLOCK_DATA;
}
if (s->metadata_preallocation && (status & BDRV_BLOCK_DATA) &&
(status & BDRV_BLOCK_OFFSET_VALID))
{
status |= BDRV_BLOCK_RECURSE;
}
return status;
}
static coroutine_fn int qcow2_handle_l2meta(BlockDriverState *bs,
QCowL2Meta **pl2meta,
bool link_l2)
{
int ret = 0;
QCowL2Meta *l2meta = *pl2meta;
while (l2meta != NULL) {
QCowL2Meta *next;
if (link_l2) {
ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
if (ret) {
goto out;
}
} else {
qcow2_alloc_cluster_abort(bs, l2meta);
}
/* Take the request off the list of running requests */
QLIST_REMOVE(l2meta, next_in_flight);
qemu_co_queue_restart_all(&l2meta->dependent_requests);
next = l2meta->next;
g_free(l2meta);
l2meta = next;
}
out:
*pl2meta = l2meta;
return ret;
}
static coroutine_fn int
qcow2_co_preadv_encrypted(BlockDriverState *bs,
uint64_t host_offset,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
uint64_t qiov_offset)
{
int ret;
BDRVQcow2State *s = bs->opaque;
uint8_t *buf;
assert(bs->encrypted && s->crypto);
assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
/*
* For encrypted images, read everything into a temporary
* contiguous buffer on which the AES functions can work.
* Also, decryption in a separate buffer is better as it
* prevents the guest from learning information about the
* encrypted nature of the virtual disk.
*/
buf = qemu_try_blockalign(s->data_file->bs, bytes);
if (buf == NULL) {
return -ENOMEM;
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
ret = bdrv_co_pread(s->data_file, host_offset, bytes, buf, 0);
if (ret < 0) {
goto fail;
}
if (qcow2_co_decrypt(bs, host_offset, offset, buf, bytes) < 0)
{
ret = -EIO;
goto fail;
}
qemu_iovec_from_buf(qiov, qiov_offset, buf, bytes);
fail:
qemu_vfree(buf);
return ret;
}
typedef struct Qcow2AioTask {
AioTask task;
BlockDriverState *bs;
QCow2SubclusterType subcluster_type; /* only for read */
uint64_t host_offset; /* or l2_entry for compressed read */
uint64_t offset;
uint64_t bytes;
QEMUIOVector *qiov;
uint64_t qiov_offset;
QCowL2Meta *l2meta; /* only for write */
} Qcow2AioTask;
static coroutine_fn int qcow2_co_preadv_task_entry(AioTask *task);
static coroutine_fn int qcow2_add_task(BlockDriverState *bs,
AioTaskPool *pool,
AioTaskFunc func,
QCow2SubclusterType subcluster_type,
uint64_t host_offset,
uint64_t offset,
uint64_t bytes,
QEMUIOVector *qiov,
size_t qiov_offset,
QCowL2Meta *l2meta)
{
Qcow2AioTask local_task;
Qcow2AioTask *task = pool ? g_new(Qcow2AioTask, 1) : &local_task;
*task = (Qcow2AioTask) {
.task.func = func,
.bs = bs,
.subcluster_type = subcluster_type,
.qiov = qiov,
.host_offset = host_offset,
.offset = offset,
.bytes = bytes,
.qiov_offset = qiov_offset,
.l2meta = l2meta,
};
trace_qcow2_add_task(qemu_coroutine_self(), bs, pool,
func == qcow2_co_preadv_task_entry ? "read" : "write",
subcluster_type, host_offset, offset, bytes,
qiov, qiov_offset);
if (!pool) {
return func(&task->task);
}
aio_task_pool_start_task(pool, &task->task);
return 0;
}
static coroutine_fn int qcow2_co_preadv_task(BlockDriverState *bs,
QCow2SubclusterType subc_type,
uint64_t host_offset,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov,
size_t qiov_offset)
{
BDRVQcow2State *s = bs->opaque;
switch (subc_type) {
case QCOW2_SUBCLUSTER_ZERO_PLAIN:
case QCOW2_SUBCLUSTER_ZERO_ALLOC:
/* Both zero types are handled in qcow2_co_preadv_part */
g_assert_not_reached();
case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
assert(bs->backing); /* otherwise handled in qcow2_co_preadv_part */
BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
return bdrv_co_preadv_part(bs->backing, offset, bytes,
qiov, qiov_offset, 0);
case QCOW2_SUBCLUSTER_COMPRESSED:
return qcow2_co_preadv_compressed(bs, host_offset,
offset, bytes, qiov, qiov_offset);
case QCOW2_SUBCLUSTER_NORMAL:
if (bs->encrypted) {
return qcow2_co_preadv_encrypted(bs, host_offset,
offset, bytes, qiov, qiov_offset);
}
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
return bdrv_co_preadv_part(s->data_file, host_offset,
bytes, qiov, qiov_offset, 0);
default:
g_assert_not_reached();
}
g_assert_not_reached();
}
static coroutine_fn int qcow2_co_preadv_task_entry(AioTask *task)
{
Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
assert(!t->l2meta);
return qcow2_co_preadv_task(t->bs, t->subcluster_type,
t->host_offset, t->offset, t->bytes,
t->qiov, t->qiov_offset);
}
static coroutine_fn int qcow2_co_preadv_part(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov,
size_t qiov_offset,
BdrvRequestFlags flags)
{
BDRVQcow2State *s = bs->opaque;
int ret = 0;
unsigned int cur_bytes; /* number of bytes in current iteration */
uint64_t host_offset = 0;
QCow2SubclusterType type;
AioTaskPool *aio = NULL;
while (bytes != 0 && aio_task_pool_status(aio) == 0) {
/* prepare next request */
cur_bytes = MIN(bytes, INT_MAX);
if (s->crypto) {
cur_bytes = MIN(cur_bytes,
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
}
qemu_co_mutex_lock(&s->lock);
ret = qcow2_get_host_offset(bs, offset, &cur_bytes,
&host_offset, &type);
qemu_co_mutex_unlock(&s->lock);
if (ret < 0) {
goto out;
}
if (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
(type == QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN && !bs->backing) ||
(type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC && !bs->backing))
{
qemu_iovec_memset(qiov, qiov_offset, 0, cur_bytes);
} else {
if (!aio && cur_bytes != bytes) {
aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
}
ret = qcow2_add_task(bs, aio, qcow2_co_preadv_task_entry, type,
host_offset, offset, cur_bytes,
qiov, qiov_offset, NULL);
if (ret < 0) {
goto out;
}
}
bytes -= cur_bytes;
offset += cur_bytes;
qiov_offset += cur_bytes;
}
out:
if (aio) {
aio_task_pool_wait_all(aio);
if (ret == 0) {
ret = aio_task_pool_status(aio);
}
g_free(aio);
}
return ret;
}
/* Check if it's possible to merge a write request with the writing of
* the data from the COW regions */
static bool merge_cow(uint64_t offset, unsigned bytes,
QEMUIOVector *qiov, size_t qiov_offset,
QCowL2Meta *l2meta)
{
QCowL2Meta *m;
for (m = l2meta; m != NULL; m = m->next) {
/* If both COW regions are empty then there's nothing to merge */
if (m->cow_start.nb_bytes == 0 && m->cow_end.nb_bytes == 0) {
continue;
}
/* If COW regions are handled already, skip this too */
if (m->skip_cow) {
continue;
}
/*
* The write request should start immediately after the first
* COW region. This does not always happen because the area
* touched by the request can be larger than the one defined
* by @m (a single request can span an area consisting of a
* mix of previously unallocated and allocated clusters, that
* is why @l2meta is a list).
*/
if (l2meta_cow_start(m) + m->cow_start.nb_bytes != offset) {
/* In this case the request starts before this region */
assert(offset < l2meta_cow_start(m));
assert(m->cow_start.nb_bytes == 0);
continue;
}
/* The write request should end immediately before the second
* COW region (see above for why it does not always happen) */
if (m->offset + m->cow_end.offset != offset + bytes) {
assert(offset + bytes > m->offset + m->cow_end.offset);
assert(m->cow_end.nb_bytes == 0);
continue;
}
/* Make sure that adding both COW regions to the QEMUIOVector
* does not exceed IOV_MAX */
if (qemu_iovec_subvec_niov(qiov, qiov_offset, bytes) > IOV_MAX - 2) {
continue;
}
m->data_qiov = qiov;
m->data_qiov_offset = qiov_offset;
return true;
}
return false;
}
/*
* Return 1 if the COW regions read as zeroes, 0 if not, < 0 on error.
* Note that returning 0 does not guarantee non-zero data.
*/
static int is_zero_cow(BlockDriverState *bs, QCowL2Meta *m)
{
/*
* This check is designed for optimization shortcut so it must be
* efficient.
* Instead of is_zero(), use bdrv_co_is_zero_fast() as it is
* faster (but not as accurate and can result in false negatives).
*/
int ret = bdrv_co_is_zero_fast(bs, m->offset + m->cow_start.offset,
m->cow_start.nb_bytes);
if (ret <= 0) {
return ret;
}
return bdrv_co_is_zero_fast(bs, m->offset + m->cow_end.offset,
m->cow_end.nb_bytes);
}
static int handle_alloc_space(BlockDriverState *bs, QCowL2Meta *l2meta)
{
BDRVQcow2State *s = bs->opaque;
QCowL2Meta *m;
if (!(s->data_file->bs->supported_zero_flags & BDRV_REQ_NO_FALLBACK)) {
return 0;
}
if (bs->encrypted) {
return 0;
}
for (m = l2meta; m != NULL; m = m->next) {
int ret;
uint64_t start_offset = m->alloc_offset + m->cow_start.offset;
unsigned nb_bytes = m->cow_end.offset + m->cow_end.nb_bytes -
m->cow_start.offset;
if (!m->cow_start.nb_bytes && !m->cow_end.nb_bytes) {
continue;
}
ret = is_zero_cow(bs, m);
if (ret < 0) {
return ret;
} else if (ret == 0) {
continue;
}
/*
* instead of writing zero COW buffers,
* efficiently zero out the whole clusters
*/
ret = qcow2_pre_write_overlap_check(bs, 0, start_offset, nb_bytes,
true);
if (ret < 0) {
return ret;
}
BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_SPACE);
ret = bdrv_co_pwrite_zeroes(s->data_file, start_offset, nb_bytes,
BDRV_REQ_NO_FALLBACK);
if (ret < 0) {
if (ret != -ENOTSUP && ret != -EAGAIN) {
return ret;
}
continue;
}
trace_qcow2_skip_cow(qemu_coroutine_self(), m->offset, m->nb_clusters);
m->skip_cow = true;
}
return 0;
}
/*
* qcow2_co_pwritev_task
* Called with s->lock unlocked
* l2meta - if not NULL, qcow2_co_pwritev_task() will consume it. Caller must
* not use it somehow after qcow2_co_pwritev_task() call
*/
static coroutine_fn int qcow2_co_pwritev_task(BlockDriverState *bs,
uint64_t host_offset,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov,
uint64_t qiov_offset,
QCowL2Meta *l2meta)
{
int ret;
BDRVQcow2State *s = bs->opaque;
void *crypt_buf = NULL;
QEMUIOVector encrypted_qiov;
if (bs->encrypted) {
assert(s->crypto);
assert(bytes <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
crypt_buf = qemu_try_blockalign(bs->file->bs, bytes);
if (crypt_buf == NULL) {
ret = -ENOMEM;
goto out_unlocked;
}
qemu_iovec_to_buf(qiov, qiov_offset, crypt_buf, bytes);
if (qcow2_co_encrypt(bs, host_offset, offset, crypt_buf, bytes) < 0) {
ret = -EIO;
goto out_unlocked;
}
qemu_iovec_init_buf(&encrypted_qiov, crypt_buf, bytes);
qiov = &encrypted_qiov;
qiov_offset = 0;
}
/* Try to efficiently initialize the physical space with zeroes */
ret = handle_alloc_space(bs, l2meta);
if (ret < 0) {
goto out_unlocked;
}
/*
* If we need to do COW, check if it's possible to merge the
* writing of the guest data together with that of the COW regions.
* If it's not possible (or not necessary) then write the
* guest data now.
*/
if (!merge_cow(offset, bytes, qiov, qiov_offset, l2meta)) {
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
trace_qcow2_writev_data(qemu_coroutine_self(), host_offset);
ret = bdrv_co_pwritev_part(s->data_file, host_offset,
bytes, qiov, qiov_offset, 0);
if (ret < 0) {
goto out_unlocked;
}
}
qemu_co_mutex_lock(&s->lock);
ret = qcow2_handle_l2meta(bs, &l2meta, true);
goto out_locked;
out_unlocked:
qemu_co_mutex_lock(&s->lock);
out_locked:
qcow2_handle_l2meta(bs, &l2meta, false);
qemu_co_mutex_unlock(&s->lock);
qemu_vfree(crypt_buf);
return ret;
}
static coroutine_fn int qcow2_co_pwritev_task_entry(AioTask *task)
{
Qcow2AioTask *t = container_of(task, Qcow2AioTask, task);
assert(!t->subcluster_type);
return qcow2_co_pwritev_task(t->bs, t->host_offset,
t->offset, t->bytes, t->qiov, t->qiov_offset,
t->l2meta);
}
static coroutine_fn int qcow2_co_pwritev_part(
BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset, BdrvRequestFlags flags)
{
BDRVQcow2State *s = bs->opaque;
int offset_in_cluster;
int ret;
unsigned int cur_bytes; /* number of sectors in current iteration */
uint64_t host_offset;
QCowL2Meta *l2meta = NULL;
AioTaskPool *aio = NULL;
trace_qcow2_writev_start_req(qemu_coroutine_self(), offset, bytes);
while (bytes != 0 && aio_task_pool_status(aio) == 0) {
l2meta = NULL;
trace_qcow2_writev_start_part(qemu_coroutine_self());
offset_in_cluster = offset_into_cluster(s, offset);
cur_bytes = MIN(bytes, INT_MAX);
if (bs->encrypted) {
cur_bytes = MIN(cur_bytes,
QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
- offset_in_cluster);
}
qemu_co_mutex_lock(&s->lock);
ret = qcow2_alloc_host_offset(bs, offset, &cur_bytes,
&host_offset, &l2meta);
if (ret < 0) {
goto out_locked;
}
ret = qcow2_pre_write_overlap_check(bs, 0, host_offset,
cur_bytes, true);
if (ret < 0) {
goto out_locked;
}
qemu_co_mutex_unlock(&s->lock);
if (!aio && cur_bytes != bytes) {
aio = aio_task_pool_new(QCOW2_MAX_WORKERS);
}
ret = qcow2_add_task(bs, aio, qcow2_co_pwritev_task_entry, 0,
host_offset, offset,
cur_bytes, qiov, qiov_offset, l2meta);
l2meta = NULL; /* l2meta is consumed by qcow2_co_pwritev_task() */
if (ret < 0) {
goto fail_nometa;
}
bytes -= cur_bytes;
offset += cur_bytes;
qiov_offset += cur_bytes;
trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_bytes);
}
ret = 0;
qemu_co_mutex_lock(&s->lock);
out_locked:
qcow2_handle_l2meta(bs, &l2meta, false);
qemu_co_mutex_unlock(&s->lock);
fail_nometa:
if (aio) {
aio_task_pool_wait_all(aio);
if (ret == 0) {
ret = aio_task_pool_status(aio);
}
g_free(aio);
}
trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);
return ret;
}
static int qcow2_inactivate(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
int ret, result = 0;
Error *local_err = NULL;
qcow2_store_persistent_dirty_bitmaps(bs, true, &local_err);
if (local_err != NULL) {
result = -EINVAL;
error_reportf_err(local_err, "Lost persistent bitmaps during "
"inactivation of node '%s': ",
bdrv_get_device_or_node_name(bs));
}
ret = qcow2_cache_flush(bs, s->l2_table_cache);
if (ret) {
result = ret;
error_report("Failed to flush the L2 table cache: %s",
strerror(-ret));
}
ret = qcow2_cache_flush(bs, s->refcount_block_cache);
if (ret) {
result = ret;
error_report("Failed to flush the refcount block cache: %s",
strerror(-ret));
}
if (result == 0) {
qcow2_mark_clean(bs);
}
return result;
}
static void qcow2_close(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
qemu_vfree(s->l1_table);
/* else pre-write overlap checks in cache_destroy may crash */
s->l1_table = NULL;
if (!(s->flags & BDRV_O_INACTIVE)) {
qcow2_inactivate(bs);
}
cache_clean_timer_del(bs);
qcow2_cache_destroy(s->l2_table_cache);
qcow2_cache_destroy(s->refcount_block_cache);
qcrypto_block_free(s->crypto);
s->crypto = NULL;
qapi_free_QCryptoBlockOpenOptions(s->crypto_opts);
g_free(s->unknown_header_fields);
cleanup_unknown_header_ext(bs);
g_free(s->image_data_file);
g_free(s->image_backing_file);
g_free(s->image_backing_format);
if (has_data_file(bs)) {
bdrv_unref_child(bs, s->data_file);
s->data_file = NULL;
}
qcow2_refcount_close(bs);
qcow2_free_snapshots(bs);
}
static void coroutine_fn qcow2_co_invalidate_cache(BlockDriverState *bs,
Error **errp)
{
ERRP_GUARD();
BDRVQcow2State *s = bs->opaque;
int flags = s->flags;
QCryptoBlock *crypto = NULL;
QDict *options;
int ret;
/*
* Backing files are read-only which makes all of their metadata immutable,
* that means we don't have to worry about reopening them here.
*/
crypto = s->crypto;
s->crypto = NULL;
qcow2_close(bs);
memset(s, 0, sizeof(BDRVQcow2State));
options = qdict_clone_shallow(bs->options);
flags &= ~BDRV_O_INACTIVE;
qemu_co_mutex_lock(&s->lock);
ret = qcow2_do_open(bs, options, flags, errp);
qemu_co_mutex_unlock(&s->lock);
qobject_unref(options);
if (ret < 0) {
error_prepend(errp, "Could not reopen qcow2 layer: ");
bs->drv = NULL;
return;
}
s->crypto = crypto;
}
static size_t header_ext_add(char *buf, uint32_t magic, const void *s,
size_t len, size_t buflen)
{
QCowExtension *ext_backing_fmt = (QCowExtension*) buf;
size_t ext_len = sizeof(QCowExtension) + ((len + 7) & ~7);
if (buflen < ext_len) {
return -ENOSPC;
}
*ext_backing_fmt = (QCowExtension) {
.magic = cpu_to_be32(magic),
.len = cpu_to_be32(len),
};
if (len) {
memcpy(buf + sizeof(QCowExtension), s, len);
}
return ext_len;
}
/*
* Updates the qcow2 header, including the variable length parts of it, i.e.
* the backing file name and all extensions. qcow2 was not designed to allow
* such changes, so if we run out of space (we can only use the first cluster)
* this function may fail.
*
* Returns 0 on success, -errno in error cases.
*/
int qcow2_update_header(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
QCowHeader *header;
char *buf;
size_t buflen = s->cluster_size;
int ret;
uint64_t total_size;
uint32_t refcount_table_clusters;
size_t header_length;
Qcow2UnknownHeaderExtension *uext;
buf = qemu_blockalign(bs, buflen);
/* Header structure */
header = (QCowHeader*) buf;
if (buflen < sizeof(*header)) {
ret = -ENOSPC;
goto fail;
}
header_length = sizeof(*header) + s->unknown_header_fields_size;
total_size = bs->total_sectors * BDRV_SECTOR_SIZE;
refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
ret = validate_compression_type(s, NULL);
if (ret) {
goto fail;
}
*header = (QCowHeader) {
/* Version 2 fields */
.magic = cpu_to_be32(QCOW_MAGIC),
.version = cpu_to_be32(s->qcow_version),
.backing_file_offset = 0,
.backing_file_size = 0,
.cluster_bits = cpu_to_be32(s->cluster_bits),
.size = cpu_to_be64(total_size),
.crypt_method = cpu_to_be32(s->crypt_method_header),
.l1_size = cpu_to_be32(s->l1_size),
.l1_table_offset = cpu_to_be64(s->l1_table_offset),
.refcount_table_offset = cpu_to_be64(s->refcount_table_offset),
.refcount_table_clusters = cpu_to_be32(refcount_table_clusters),
.nb_snapshots = cpu_to_be32(s->nb_snapshots),
.snapshots_offset = cpu_to_be64(s->snapshots_offset),
/* Version 3 fields */
.incompatible_features = cpu_to_be64(s->incompatible_features),
.compatible_features = cpu_to_be64(s->compatible_features),
.autoclear_features = cpu_to_be64(s->autoclear_features),
.refcount_order = cpu_to_be32(s->refcount_order),
.header_length = cpu_to_be32(header_length),
.compression_type = s->compression_type,
};
/* For older versions, write a shorter header */
switch (s->qcow_version) {
case 2:
ret = offsetof(QCowHeader, incompatible_features);
break;
case 3:
ret = sizeof(*header);
break;
default:
ret = -EINVAL;
goto fail;
}
buf += ret;
buflen -= ret;
memset(buf, 0, buflen);
/* Preserve any unknown field in the header */
if (s->unknown_header_fields_size) {
if (buflen < s->unknown_header_fields_size) {
ret = -ENOSPC;
goto fail;
}
memcpy(buf, s->unknown_header_fields, s->unknown_header_fields_size);
buf += s->unknown_header_fields_size;
buflen -= s->unknown_header_fields_size;
}
/* Backing file format header extension */
if (s->image_backing_format) {
ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BACKING_FORMAT,
s->image_backing_format,
strlen(s->image_backing_format),
buflen);
if (ret < 0) {
goto fail;
}
buf += ret;
buflen -= ret;
}
/* External data file header extension */
if (has_data_file(bs) && s->image_data_file) {
ret = header_ext_add(buf, QCOW2_EXT_MAGIC_DATA_FILE,
s->image_data_file, strlen(s->image_data_file),
buflen);
if (ret < 0) {
goto fail;
}
buf += ret;
buflen -= ret;
}
/* Full disk encryption header pointer extension */
if (s->crypto_header.offset != 0) {
s->crypto_header.offset = cpu_to_be64(s->crypto_header.offset);
s->crypto_header.length = cpu_to_be64(s->crypto_header.length);
ret = header_ext_add(buf, QCOW2_EXT_MAGIC_CRYPTO_HEADER,
&s->crypto_header, sizeof(s->crypto_header),
buflen);
s->crypto_header.offset = be64_to_cpu(s->crypto_header.offset);
s->crypto_header.length = be64_to_cpu(s->crypto_header.length);
if (ret < 0) {
goto fail;
}
buf += ret;
buflen -= ret;
}
/*
* Feature table. A mere 8 feature names occupies 392 bytes, and
* when coupled with the v3 minimum header of 104 bytes plus the
* 8-byte end-of-extension marker, that would leave only 8 bytes
* for a backing file name in an image with 512-byte clusters.
* Thus, we choose to omit this header for cluster sizes 4k and
* smaller.
*/
if (s->qcow_version >= 3 && s->cluster_size > 4096) {
static const Qcow2Feature features[] = {
{
.type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
.bit = QCOW2_INCOMPAT_DIRTY_BITNR,
.name = "dirty bit",
},
{
.type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
.bit = QCOW2_INCOMPAT_CORRUPT_BITNR,
.name = "corrupt bit",
},
{
.type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
.bit = QCOW2_INCOMPAT_DATA_FILE_BITNR,
.name = "external data file",
},
{
.type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
.bit = QCOW2_INCOMPAT_COMPRESSION_BITNR,
.name = "compression type",
},
{
.type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
.bit = QCOW2_INCOMPAT_EXTL2_BITNR,
.name = "extended L2 entries",