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qemu-e2k/block/qcow2-bitmap.c
Max Reitz c9ceb3ec8a qcow2: No persistent dirty bitmaps for compat=0.10 
Persistent dirty bitmaps require a properly functioning
autoclear_features field, or we cannot track when an unsupporting
program might overwrite them.  Therefore, we cannot support them for
compat=0.10 images.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20171123020832.8165-3-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-01-23 12:34:42 +01:00

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/*
* Bitmaps for the QCOW version 2 format
*
* Copyright (c) 2014-2017 Vladimir Sementsov-Ogievskiy
*
* This file is derived from qcow2-snapshot.c, original copyright:
* 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 "qapi/error.h"
#include "qemu/cutils.h"
#include "block/block_int.h"
#include "block/qcow2.h"
/* NOTICE: BME here means Bitmaps Extension and used as a namespace for
* _internal_ constants. Please do not use this _internal_ abbreviation for
* other needs and/or outside of this file. */
/* Bitmap directory entry constraints */
#define BME_MAX_TABLE_SIZE 0x8000000
#define BME_MAX_PHYS_SIZE 0x20000000 /* restrict BdrvDirtyBitmap size in RAM */
#define BME_MAX_GRANULARITY_BITS 31
#define BME_MIN_GRANULARITY_BITS 9
#define BME_MAX_NAME_SIZE 1023
#if BME_MAX_TABLE_SIZE * 8ULL > INT_MAX
#error In the code bitmap table physical size assumed to fit into int
#endif
/* Bitmap directory entry flags */
#define BME_RESERVED_FLAGS 0xfffffffcU
#define BME_FLAG_IN_USE (1U << 0)
#define BME_FLAG_AUTO (1U << 1)
/* bits [1, 8] U [56, 63] are reserved */
#define BME_TABLE_ENTRY_RESERVED_MASK 0xff000000000001feULL
#define BME_TABLE_ENTRY_OFFSET_MASK 0x00fffffffffffe00ULL
#define BME_TABLE_ENTRY_FLAG_ALL_ONES (1ULL << 0)
typedef struct QEMU_PACKED Qcow2BitmapDirEntry {
/* header is 8 byte aligned */
uint64_t bitmap_table_offset;
uint32_t bitmap_table_size;
uint32_t flags;
uint8_t type;
uint8_t granularity_bits;
uint16_t name_size;
uint32_t extra_data_size;
/* extra data follows */
/* name follows */
} Qcow2BitmapDirEntry;
typedef struct Qcow2BitmapTable {
uint64_t offset;
uint32_t size; /* number of 64bit entries */
QSIMPLEQ_ENTRY(Qcow2BitmapTable) entry;
} Qcow2BitmapTable;
typedef QSIMPLEQ_HEAD(Qcow2BitmapTableList, Qcow2BitmapTable)
Qcow2BitmapTableList;
typedef struct Qcow2Bitmap {
Qcow2BitmapTable table;
uint32_t flags;
uint8_t granularity_bits;
char *name;
BdrvDirtyBitmap *dirty_bitmap;
QSIMPLEQ_ENTRY(Qcow2Bitmap) entry;
} Qcow2Bitmap;
typedef QSIMPLEQ_HEAD(Qcow2BitmapList, Qcow2Bitmap) Qcow2BitmapList;
typedef enum BitmapType {
BT_DIRTY_TRACKING_BITMAP = 1
} BitmapType;
static inline bool can_write(BlockDriverState *bs)
{
return !bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE);
}
static int update_header_sync(BlockDriverState *bs)
{
int ret;
ret = qcow2_update_header(bs);
if (ret < 0) {
return ret;
}
return bdrv_flush(bs);
}
static inline void bitmap_table_to_be(uint64_t *bitmap_table, size_t size)
{
size_t i;
for (i = 0; i < size; ++i) {
cpu_to_be64s(&bitmap_table[i]);
}
}
static int check_table_entry(uint64_t entry, int cluster_size)
{
uint64_t offset;
if (entry & BME_TABLE_ENTRY_RESERVED_MASK) {
return -EINVAL;
}
offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
if (offset != 0) {
/* if offset specified, bit 0 is reserved */
if (entry & BME_TABLE_ENTRY_FLAG_ALL_ONES) {
return -EINVAL;
}
if (offset % cluster_size != 0) {
return -EINVAL;
}
}
return 0;
}
static int check_constraints_on_bitmap(BlockDriverState *bs,
const char *name,
uint32_t granularity,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
int granularity_bits = ctz32(granularity);
int64_t len = bdrv_getlength(bs);
assert(granularity > 0);
assert((granularity & (granularity - 1)) == 0);
if (len < 0) {
error_setg_errno(errp, -len, "Failed to get size of '%s'",
bdrv_get_device_or_node_name(bs));
return len;
}
if (granularity_bits > BME_MAX_GRANULARITY_BITS) {
error_setg(errp, "Granularity exceeds maximum (%llu bytes)",
1ULL << BME_MAX_GRANULARITY_BITS);
return -EINVAL;
}
if (granularity_bits < BME_MIN_GRANULARITY_BITS) {
error_setg(errp, "Granularity is under minimum (%llu bytes)",
1ULL << BME_MIN_GRANULARITY_BITS);
return -EINVAL;
}
if ((len > (uint64_t)BME_MAX_PHYS_SIZE << granularity_bits) ||
(len > (uint64_t)BME_MAX_TABLE_SIZE * s->cluster_size <<
granularity_bits))
{
error_setg(errp, "Too much space will be occupied by the bitmap. "
"Use larger granularity");
return -EINVAL;
}
if (strlen(name) > BME_MAX_NAME_SIZE) {
error_setg(errp, "Name length exceeds maximum (%u characters)",
BME_MAX_NAME_SIZE);
return -EINVAL;
}
return 0;
}
static void clear_bitmap_table(BlockDriverState *bs, uint64_t *bitmap_table,
uint32_t bitmap_table_size)
{
BDRVQcow2State *s = bs->opaque;
int i;
for (i = 0; i < bitmap_table_size; ++i) {
uint64_t addr = bitmap_table[i] & BME_TABLE_ENTRY_OFFSET_MASK;
if (!addr) {
continue;
}
qcow2_free_clusters(bs, addr, s->cluster_size, QCOW2_DISCARD_OTHER);
bitmap_table[i] = 0;
}
}
static int bitmap_table_load(BlockDriverState *bs, Qcow2BitmapTable *tb,
uint64_t **bitmap_table)
{
int ret;
BDRVQcow2State *s = bs->opaque;
uint32_t i;
uint64_t *table;
assert(tb->size != 0);
table = g_try_new(uint64_t, tb->size);
if (table == NULL) {
return -ENOMEM;
}
assert(tb->size <= BME_MAX_TABLE_SIZE);
ret = bdrv_pread(bs->file, tb->offset,
table, tb->size * sizeof(uint64_t));
if (ret < 0) {
goto fail;
}
for (i = 0; i < tb->size; ++i) {
be64_to_cpus(&table[i]);
ret = check_table_entry(table[i], s->cluster_size);
if (ret < 0) {
goto fail;
}
}
*bitmap_table = table;
return 0;
fail:
g_free(table);
return ret;
}
static int free_bitmap_clusters(BlockDriverState *bs, Qcow2BitmapTable *tb)
{
int ret;
uint64_t *bitmap_table;
ret = bitmap_table_load(bs, tb, &bitmap_table);
if (ret < 0) {
assert(bitmap_table == NULL);
return ret;
}
clear_bitmap_table(bs, bitmap_table, tb->size);
qcow2_free_clusters(bs, tb->offset, tb->size * sizeof(uint64_t),
QCOW2_DISCARD_OTHER);
g_free(bitmap_table);
tb->offset = 0;
tb->size = 0;
return 0;
}
/* Return the disk size covered by a single qcow2 cluster of bitmap data. */
static uint64_t bytes_covered_by_bitmap_cluster(const BDRVQcow2State *s,
const BdrvDirtyBitmap *bitmap)
{
uint64_t granularity = bdrv_dirty_bitmap_granularity(bitmap);
uint64_t limit = granularity * (s->cluster_size << 3);
assert(QEMU_IS_ALIGNED(limit,
bdrv_dirty_bitmap_serialization_align(bitmap)));
return limit;
}
/* load_bitmap_data
* @bitmap_table entries must satisfy specification constraints.
* @bitmap must be cleared */
static int load_bitmap_data(BlockDriverState *bs,
const uint64_t *bitmap_table,
uint32_t bitmap_table_size,
BdrvDirtyBitmap *bitmap)
{
int ret = 0;
BDRVQcow2State *s = bs->opaque;
uint64_t offset, limit;
uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
uint8_t *buf = NULL;
uint64_t i, tab_size =
size_to_clusters(s,
bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
if (tab_size != bitmap_table_size || tab_size > BME_MAX_TABLE_SIZE) {
return -EINVAL;
}
buf = g_malloc(s->cluster_size);
limit = bytes_covered_by_bitmap_cluster(s, bitmap);
for (i = 0, offset = 0; i < tab_size; ++i, offset += limit) {
uint64_t count = MIN(bm_size - offset, limit);
uint64_t entry = bitmap_table[i];
uint64_t data_offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
assert(check_table_entry(entry, s->cluster_size) == 0);
if (data_offset == 0) {
if (entry & BME_TABLE_ENTRY_FLAG_ALL_ONES) {
bdrv_dirty_bitmap_deserialize_ones(bitmap, offset, count,
false);
} else {
/* No need to deserialize zeros because the dirty bitmap is
* already cleared */
}
} else {
ret = bdrv_pread(bs->file, data_offset, buf, s->cluster_size);
if (ret < 0) {
goto finish;
}
bdrv_dirty_bitmap_deserialize_part(bitmap, buf, offset, count,
false);
}
}
ret = 0;
bdrv_dirty_bitmap_deserialize_finish(bitmap);
finish:
g_free(buf);
return ret;
}
static BdrvDirtyBitmap *load_bitmap(BlockDriverState *bs,
Qcow2Bitmap *bm, Error **errp)
{
int ret;
uint64_t *bitmap_table = NULL;
uint32_t granularity;
BdrvDirtyBitmap *bitmap = NULL;
if (bm->flags & BME_FLAG_IN_USE) {
error_setg(errp, "Bitmap '%s' is in use", bm->name);
goto fail;
}
ret = bitmap_table_load(bs, &bm->table, &bitmap_table);
if (ret < 0) {
error_setg_errno(errp, -ret,
"Could not read bitmap_table table from image for "
"bitmap '%s'", bm->name);
goto fail;
}
granularity = 1U << bm->granularity_bits;
bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);
if (bitmap == NULL) {
goto fail;
}
ret = load_bitmap_data(bs, bitmap_table, bm->table.size, bitmap);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read bitmap '%s' from image",
bm->name);
goto fail;
}
g_free(bitmap_table);
return bitmap;
fail:
g_free(bitmap_table);
if (bitmap != NULL) {
bdrv_release_dirty_bitmap(bs, bitmap);
}
return NULL;
}
/*
* Bitmap List
*/
/*
* Bitmap List private functions
* Only Bitmap List knows about bitmap directory structure in Qcow2.
*/
static inline void bitmap_dir_entry_to_cpu(Qcow2BitmapDirEntry *entry)
{
be64_to_cpus(&entry->bitmap_table_offset);
be32_to_cpus(&entry->bitmap_table_size);
be32_to_cpus(&entry->flags);
be16_to_cpus(&entry->name_size);
be32_to_cpus(&entry->extra_data_size);
}
static inline void bitmap_dir_entry_to_be(Qcow2BitmapDirEntry *entry)
{
cpu_to_be64s(&entry->bitmap_table_offset);
cpu_to_be32s(&entry->bitmap_table_size);
cpu_to_be32s(&entry->flags);
cpu_to_be16s(&entry->name_size);
cpu_to_be32s(&entry->extra_data_size);
}
static inline int calc_dir_entry_size(size_t name_size, size_t extra_data_size)
{
return align_offset(sizeof(Qcow2BitmapDirEntry) +
name_size + extra_data_size, 8);
}
static inline int dir_entry_size(Qcow2BitmapDirEntry *entry)
{
return calc_dir_entry_size(entry->name_size, entry->extra_data_size);
}
static inline const char *dir_entry_name_field(Qcow2BitmapDirEntry *entry)
{
return (const char *)(entry + 1) + entry->extra_data_size;
}
static inline char *dir_entry_copy_name(Qcow2BitmapDirEntry *entry)
{
const char *name_field = dir_entry_name_field(entry);
return g_strndup(name_field, entry->name_size);
}
static inline Qcow2BitmapDirEntry *next_dir_entry(Qcow2BitmapDirEntry *entry)
{
return (Qcow2BitmapDirEntry *)((uint8_t *)entry + dir_entry_size(entry));
}
static int check_dir_entry(BlockDriverState *bs, Qcow2BitmapDirEntry *entry)
{
BDRVQcow2State *s = bs->opaque;
uint64_t phys_bitmap_bytes;
int64_t len;
bool fail = (entry->bitmap_table_size == 0) ||
(entry->bitmap_table_offset == 0) ||
(entry->bitmap_table_offset % s->cluster_size) ||
(entry->bitmap_table_size > BME_MAX_TABLE_SIZE) ||
(entry->granularity_bits > BME_MAX_GRANULARITY_BITS) ||
(entry->granularity_bits < BME_MIN_GRANULARITY_BITS) ||
(entry->flags & BME_RESERVED_FLAGS) ||
(entry->name_size > BME_MAX_NAME_SIZE) ||
(entry->type != BT_DIRTY_TRACKING_BITMAP);
if (fail) {
return -EINVAL;
}
phys_bitmap_bytes = (uint64_t)entry->bitmap_table_size * s->cluster_size;
len = bdrv_getlength(bs);
if (len < 0) {
return len;
}
fail = (phys_bitmap_bytes > BME_MAX_PHYS_SIZE) ||
(len > ((phys_bitmap_bytes * 8) << entry->granularity_bits));
return fail ? -EINVAL : 0;
}
static inline void bitmap_directory_to_be(uint8_t *dir, size_t size)
{
uint8_t *end = dir + size;
while (dir < end) {
Qcow2BitmapDirEntry *e = (Qcow2BitmapDirEntry *)dir;
dir += dir_entry_size(e);
bitmap_dir_entry_to_be(e);
}
}
/*
* Bitmap List public functions
*/
static void bitmap_free(Qcow2Bitmap *bm)
{
if (bm == NULL) {
return;
}
g_free(bm->name);
g_free(bm);
}
static void bitmap_list_free(Qcow2BitmapList *bm_list)
{
Qcow2Bitmap *bm;
if (bm_list == NULL) {
return;
}
while ((bm = QSIMPLEQ_FIRST(bm_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(bm_list, entry);
bitmap_free(bm);
}
g_free(bm_list);
}
static Qcow2BitmapList *bitmap_list_new(void)
{
Qcow2BitmapList *bm_list = g_new(Qcow2BitmapList, 1);
QSIMPLEQ_INIT(bm_list);
return bm_list;
}
static uint32_t bitmap_list_count(Qcow2BitmapList *bm_list)
{
Qcow2Bitmap *bm;
uint32_t nb_bitmaps = 0;
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
nb_bitmaps++;
}
return nb_bitmaps;
}
/* bitmap_list_load
* Get bitmap list from qcow2 image. Actually reads bitmap directory,
* checks it and convert to bitmap list.
*/
static Qcow2BitmapList *bitmap_list_load(BlockDriverState *bs, uint64_t offset,
uint64_t size, Error **errp)
{
int ret;
BDRVQcow2State *s = bs->opaque;
uint8_t *dir, *dir_end;
Qcow2BitmapDirEntry *e;
uint32_t nb_dir_entries = 0;
Qcow2BitmapList *bm_list = NULL;
if (size == 0) {
error_setg(errp, "Requested bitmap directory size is zero");
return NULL;
}
if (size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
error_setg(errp, "Requested bitmap directory size is too big");
return NULL;
}
dir = g_try_malloc(size);
if (dir == NULL) {
error_setg(errp, "Failed to allocate space for bitmap directory");
return NULL;
}
dir_end = dir + size;
ret = bdrv_pread(bs->file, offset, dir, size);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to read bitmap directory");
goto fail;
}
bm_list = bitmap_list_new();
for (e = (Qcow2BitmapDirEntry *)dir;
e < (Qcow2BitmapDirEntry *)dir_end;
e = next_dir_entry(e))
{
Qcow2Bitmap *bm;
if ((uint8_t *)(e + 1) > dir_end) {
goto broken_dir;
}
if (++nb_dir_entries > s->nb_bitmaps) {
error_setg(errp, "More bitmaps found than specified in header"
" extension");
goto fail;
}
bitmap_dir_entry_to_cpu(e);
if ((uint8_t *)next_dir_entry(e) > dir_end) {
goto broken_dir;
}
if (e->extra_data_size != 0) {
error_setg(errp, "Bitmap extra data is not supported");
goto fail;
}
ret = check_dir_entry(bs, e);
if (ret < 0) {
error_setg(errp, "Bitmap '%.*s' doesn't satisfy the constraints",
e->name_size, dir_entry_name_field(e));
goto fail;
}
bm = g_new0(Qcow2Bitmap, 1);
bm->table.offset = e->bitmap_table_offset;
bm->table.size = e->bitmap_table_size;
bm->flags = e->flags;
bm->granularity_bits = e->granularity_bits;
bm->name = dir_entry_copy_name(e);
QSIMPLEQ_INSERT_TAIL(bm_list, bm, entry);
}
if (nb_dir_entries != s->nb_bitmaps) {
error_setg(errp, "Less bitmaps found than specified in header"
" extension");
goto fail;
}
if ((uint8_t *)e != dir_end) {
goto broken_dir;
}
g_free(dir);
return bm_list;
broken_dir:
ret = -EINVAL;
error_setg(errp, "Broken bitmap directory");
fail:
g_free(dir);
bitmap_list_free(bm_list);
return NULL;
}
int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
void **refcount_table,
int64_t *refcount_table_size)
{
int ret;
BDRVQcow2State *s = bs->opaque;
Qcow2BitmapList *bm_list;
Qcow2Bitmap *bm;
if (s->nb_bitmaps == 0) {
return 0;
}
ret = qcow2_inc_refcounts_imrt(bs, res, refcount_table, refcount_table_size,
s->bitmap_directory_offset,
s->bitmap_directory_size);
if (ret < 0) {
return ret;
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, NULL);
if (bm_list == NULL) {
res->corruptions++;
return -EINVAL;
}
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
uint64_t *bitmap_table = NULL;
int i;
ret = qcow2_inc_refcounts_imrt(bs, res,
refcount_table, refcount_table_size,
bm->table.offset,
bm->table.size * sizeof(uint64_t));
if (ret < 0) {
goto out;
}
ret = bitmap_table_load(bs, &bm->table, &bitmap_table);
if (ret < 0) {
res->corruptions++;
goto out;
}
for (i = 0; i < bm->table.size; ++i) {
uint64_t entry = bitmap_table[i];
uint64_t offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;
if (check_table_entry(entry, s->cluster_size) < 0) {
res->corruptions++;
continue;
}
if (offset == 0) {
continue;
}
ret = qcow2_inc_refcounts_imrt(bs, res,
refcount_table, refcount_table_size,
offset, s->cluster_size);
if (ret < 0) {
g_free(bitmap_table);
goto out;
}
}
g_free(bitmap_table);
}
out:
bitmap_list_free(bm_list);
return ret;
}
/* bitmap_list_store
* Store bitmap list to qcow2 image as a bitmap directory.
* Everything is checked.
*/
static int bitmap_list_store(BlockDriverState *bs, Qcow2BitmapList *bm_list,
uint64_t *offset, uint64_t *size, bool in_place)
{
int ret;
uint8_t *dir;
int64_t dir_offset = 0;
uint64_t dir_size = 0;
Qcow2Bitmap *bm;
Qcow2BitmapDirEntry *e;
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
dir_size += calc_dir_entry_size(strlen(bm->name), 0);
}
if (dir_size == 0 || dir_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
return -EINVAL;
}
if (in_place) {
if (*size != dir_size || *offset == 0) {
return -EINVAL;
}
dir_offset = *offset;
}
dir = g_try_malloc(dir_size);
if (dir == NULL) {
return -ENOMEM;
}
e = (Qcow2BitmapDirEntry *)dir;
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
e->bitmap_table_offset = bm->table.offset;
e->bitmap_table_size = bm->table.size;
e->flags = bm->flags;
e->type = BT_DIRTY_TRACKING_BITMAP;
e->granularity_bits = bm->granularity_bits;
e->name_size = strlen(bm->name);
e->extra_data_size = 0;
memcpy(e + 1, bm->name, e->name_size);
if (check_dir_entry(bs, e) < 0) {
ret = -EINVAL;
goto fail;
}
e = next_dir_entry(e);
}
bitmap_directory_to_be(dir, dir_size);
if (!in_place) {
dir_offset = qcow2_alloc_clusters(bs, dir_size);
if (dir_offset < 0) {
ret = dir_offset;
goto fail;
}
}
ret = qcow2_pre_write_overlap_check(bs, 0, dir_offset, dir_size);
if (ret < 0) {
goto fail;
}
ret = bdrv_pwrite(bs->file, dir_offset, dir, dir_size);
if (ret < 0) {
goto fail;
}
g_free(dir);
if (!in_place) {
*size = dir_size;
*offset = dir_offset;
}
return 0;
fail:
g_free(dir);
if (!in_place && dir_offset > 0) {
qcow2_free_clusters(bs, dir_offset, dir_size, QCOW2_DISCARD_OTHER);
}
return ret;
}
/*
* Bitmap List end
*/
static int update_ext_header_and_dir_in_place(BlockDriverState *bs,
Qcow2BitmapList *bm_list)
{
BDRVQcow2State *s = bs->opaque;
int ret;
if (!(s->autoclear_features & QCOW2_AUTOCLEAR_BITMAPS) ||
bm_list == NULL || QSIMPLEQ_EMPTY(bm_list) ||
bitmap_list_count(bm_list) != s->nb_bitmaps)
{
return -EINVAL;
}
s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
ret = update_header_sync(bs);
if (ret < 0) {
/* Two variants are possible here:
* 1. Autoclear flag is dropped, all bitmaps will be lost.
* 2. Autoclear flag is not dropped, old state is left.
*/
return ret;
}
/* autoclear bit is not set, so we can safely update bitmap directory */
ret = bitmap_list_store(bs, bm_list, &s->bitmap_directory_offset,
&s->bitmap_directory_size, true);
if (ret < 0) {
/* autoclear bit is cleared, so all leaked clusters would be removed on
* qemu-img check */
return ret;
}
ret = update_header_sync(bs);
if (ret < 0) {
/* autoclear bit is cleared, so all leaked clusters would be removed on
* qemu-img check */
return ret;
}
s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
return update_header_sync(bs);
/* If final update_header_sync() fails, two variants are possible:
* 1. Autoclear flag is not set, all bitmaps will be lost.
* 2. Autoclear flag is set, header and directory are successfully updated.
*/
}
static int update_ext_header_and_dir(BlockDriverState *bs,
Qcow2BitmapList *bm_list)
{
BDRVQcow2State *s = bs->opaque;
int ret;
uint64_t new_offset = 0;
uint64_t new_size = 0;
uint32_t new_nb_bitmaps = 0;
uint64_t old_offset = s->bitmap_directory_offset;
uint64_t old_size = s->bitmap_directory_size;
uint32_t old_nb_bitmaps = s->nb_bitmaps;
uint64_t old_autocl = s->autoclear_features;
if (bm_list != NULL && !QSIMPLEQ_EMPTY(bm_list)) {
new_nb_bitmaps = bitmap_list_count(bm_list);
if (new_nb_bitmaps > QCOW2_MAX_BITMAPS) {
return -EINVAL;
}
ret = bitmap_list_store(bs, bm_list, &new_offset, &new_size, false);
if (ret < 0) {
return ret;
}
ret = bdrv_flush(bs->file->bs);
if (ret < 0) {
goto fail;
}
s->autoclear_features |= QCOW2_AUTOCLEAR_BITMAPS;
} else {
s->autoclear_features &= ~(uint64_t)QCOW2_AUTOCLEAR_BITMAPS;
}
s->bitmap_directory_offset = new_offset;
s->bitmap_directory_size = new_size;
s->nb_bitmaps = new_nb_bitmaps;
ret = update_header_sync(bs);
if (ret < 0) {
goto fail;
}
if (old_size > 0) {
qcow2_free_clusters(bs, old_offset, old_size, QCOW2_DISCARD_OTHER);
}
return 0;
fail:
if (new_offset > 0) {
qcow2_free_clusters(bs, new_offset, new_size, QCOW2_DISCARD_OTHER);
}
s->bitmap_directory_offset = old_offset;
s->bitmap_directory_size = old_size;
s->nb_bitmaps = old_nb_bitmaps;
s->autoclear_features = old_autocl;
return ret;
}
/* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
static void release_dirty_bitmap_helper(gpointer bitmap,
gpointer bs)
{
bdrv_release_dirty_bitmap(bs, bitmap);
}
/* for g_slist_foreach for GSList of BdrvDirtyBitmap* elements */
static void set_readonly_helper(gpointer bitmap, gpointer value)
{
bdrv_dirty_bitmap_set_readonly(bitmap, (bool)value);
}
/* qcow2_load_autoloading_dirty_bitmaps()
* Return value is a hint for caller: true means that the Qcow2 header was
* updated. (false doesn't mean that the header should be updated by the
* caller, it just means that updating was not needed or the image cannot be
* written to).
* On failure the function returns false.
*/
bool qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp)
{
BDRVQcow2State *s = bs->opaque;
Qcow2BitmapList *bm_list;
Qcow2Bitmap *bm;
GSList *created_dirty_bitmaps = NULL;
bool header_updated = false;
if (s->nb_bitmaps == 0) {
/* No bitmaps - nothing to do */
return false;
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, errp);
if (bm_list == NULL) {
return false;
}
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
if ((bm->flags & BME_FLAG_AUTO) && !(bm->flags & BME_FLAG_IN_USE)) {
BdrvDirtyBitmap *bitmap = load_bitmap(bs, bm, errp);
if (bitmap == NULL) {
goto fail;
}
bdrv_dirty_bitmap_set_persistance(bitmap, true);
bdrv_dirty_bitmap_set_autoload(bitmap, true);
bm->flags |= BME_FLAG_IN_USE;
created_dirty_bitmaps =
g_slist_append(created_dirty_bitmaps, bitmap);
}
}
if (created_dirty_bitmaps != NULL) {
if (can_write(bs)) {
/* in_use flags must be updated */
int ret = update_ext_header_and_dir_in_place(bs, bm_list);
if (ret < 0) {
error_setg_errno(errp, -ret, "Can't update bitmap directory");
goto fail;
}
header_updated = true;
} else {
g_slist_foreach(created_dirty_bitmaps, set_readonly_helper,
(gpointer)true);
}
}
g_slist_free(created_dirty_bitmaps);
bitmap_list_free(bm_list);
return header_updated;
fail:
g_slist_foreach(created_dirty_bitmaps, release_dirty_bitmap_helper, bs);
g_slist_free(created_dirty_bitmaps);
bitmap_list_free(bm_list);
return false;
}
int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp)
{
BDRVQcow2State *s = bs->opaque;
Qcow2BitmapList *bm_list;
Qcow2Bitmap *bm;
GSList *ro_dirty_bitmaps = NULL;
int ret = 0;
if (s->nb_bitmaps == 0) {
/* No bitmaps - nothing to do */
return 0;
}
if (!can_write(bs)) {
error_setg(errp, "Can't write to the image on reopening bitmaps rw");
return -EINVAL;
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, errp);
if (bm_list == NULL) {
return -EINVAL;
}
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
if (!(bm->flags & BME_FLAG_IN_USE)) {
BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
if (bitmap == NULL) {
continue;
}
if (!bdrv_dirty_bitmap_readonly(bitmap)) {
error_setg(errp, "Bitmap %s is not readonly but not marked"
"'IN_USE' in the image. Something went wrong,"
"all the bitmaps may be corrupted", bm->name);
ret = -EINVAL;
goto out;
}
bm->flags |= BME_FLAG_IN_USE;
ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);
}
}
if (ro_dirty_bitmaps != NULL) {
/* in_use flags must be updated */
ret = update_ext_header_and_dir_in_place(bs, bm_list);
if (ret < 0) {
error_setg_errno(errp, -ret, "Can't update bitmap directory");
goto out;
}
g_slist_foreach(ro_dirty_bitmaps, set_readonly_helper, false);
}
out:
g_slist_free(ro_dirty_bitmaps);
bitmap_list_free(bm_list);
return ret;
}
/* store_bitmap_data()
* Store bitmap to image, filling bitmap table accordingly.
*/
static uint64_t *store_bitmap_data(BlockDriverState *bs,
BdrvDirtyBitmap *bitmap,
uint32_t *bitmap_table_size, Error **errp)
{
int ret;
BDRVQcow2State *s = bs->opaque;
int64_t offset;
uint64_t limit;
uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);
const char *bm_name = bdrv_dirty_bitmap_name(bitmap);
uint8_t *buf = NULL;
BdrvDirtyBitmapIter *dbi;
uint64_t *tb;
uint64_t tb_size =
size_to_clusters(s,
bdrv_dirty_bitmap_serialization_size(bitmap, 0, bm_size));
if (tb_size > BME_MAX_TABLE_SIZE ||
tb_size * s->cluster_size > BME_MAX_PHYS_SIZE)
{
error_setg(errp, "Bitmap '%s' is too big", bm_name);
return NULL;
}
tb = g_try_new0(uint64_t, tb_size);
if (tb == NULL) {
error_setg(errp, "No memory");
return NULL;
}
dbi = bdrv_dirty_iter_new(bitmap);
buf = g_malloc(s->cluster_size);
limit = bytes_covered_by_bitmap_cluster(s, bitmap);
assert(DIV_ROUND_UP(bm_size, limit) == tb_size);
while ((offset = bdrv_dirty_iter_next(dbi)) >= 0) {
uint64_t cluster = offset / limit;
uint64_t end, write_size;
int64_t off;
/*
* We found the first dirty offset, but want to write out the
* entire cluster of the bitmap that includes that offset,
* including any leading zero bits.
*/
offset = QEMU_ALIGN_DOWN(offset, limit);
end = MIN(bm_size, offset + limit);
write_size = bdrv_dirty_bitmap_serialization_size(bitmap, offset,
end - offset);
assert(write_size <= s->cluster_size);
off = qcow2_alloc_clusters(bs, s->cluster_size);
if (off < 0) {
error_setg_errno(errp, -off,
"Failed to allocate clusters for bitmap '%s'",
bm_name);
goto fail;
}
tb[cluster] = off;
bdrv_dirty_bitmap_serialize_part(bitmap, buf, offset, end - offset);
if (write_size < s->cluster_size) {
memset(buf + write_size, 0, s->cluster_size - write_size);
}
ret = qcow2_pre_write_overlap_check(bs, 0, off, s->cluster_size);
if (ret < 0) {
error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
goto fail;
}
ret = bdrv_pwrite(bs->file, off, buf, s->cluster_size);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to write bitmap '%s' to file",
bm_name);
goto fail;
}
if (end >= bm_size) {
break;
}
bdrv_set_dirty_iter(dbi, end);
}
*bitmap_table_size = tb_size;
g_free(buf);
bdrv_dirty_iter_free(dbi);
return tb;
fail:
clear_bitmap_table(bs, tb, tb_size);
g_free(buf);
bdrv_dirty_iter_free(dbi);
g_free(tb);
return NULL;
}
/* store_bitmap()
* Store bm->dirty_bitmap to qcow2.
* Set bm->table_offset and bm->table_size accordingly.
*/
static int store_bitmap(BlockDriverState *bs, Qcow2Bitmap *bm, Error **errp)
{
int ret;
uint64_t *tb;
int64_t tb_offset;
uint32_t tb_size;
BdrvDirtyBitmap *bitmap = bm->dirty_bitmap;
const char *bm_name;
assert(bitmap != NULL);
bm_name = bdrv_dirty_bitmap_name(bitmap);
tb = store_bitmap_data(bs, bitmap, &tb_size, errp);
if (tb == NULL) {
return -EINVAL;
}
assert(tb_size <= BME_MAX_TABLE_SIZE);
tb_offset = qcow2_alloc_clusters(bs, tb_size * sizeof(tb[0]));
if (tb_offset < 0) {
error_setg_errno(errp, -tb_offset,
"Failed to allocate clusters for bitmap '%s'",
bm_name);
ret = tb_offset;
goto fail;
}
ret = qcow2_pre_write_overlap_check(bs, 0, tb_offset,
tb_size * sizeof(tb[0]));
if (ret < 0) {
error_setg_errno(errp, -ret, "Qcow2 overlap check failed");
goto fail;
}
bitmap_table_to_be(tb, tb_size);
ret = bdrv_pwrite(bs->file, tb_offset, tb, tb_size * sizeof(tb[0]));
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to write bitmap '%s' to file",
bm_name);
goto fail;
}
g_free(tb);
bm->table.offset = tb_offset;
bm->table.size = tb_size;
return 0;
fail:
clear_bitmap_table(bs, tb, tb_size);
if (tb_offset > 0) {
qcow2_free_clusters(bs, tb_offset, tb_size * sizeof(tb[0]),
QCOW2_DISCARD_OTHER);
}
g_free(tb);
return ret;
}
static Qcow2Bitmap *find_bitmap_by_name(Qcow2BitmapList *bm_list,
const char *name)
{
Qcow2Bitmap *bm;
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
if (strcmp(name, bm->name) == 0) {
return bm;
}
}
return NULL;
}
void qcow2_remove_persistent_dirty_bitmap(BlockDriverState *bs,
const char *name,
Error **errp)
{
int ret;
BDRVQcow2State *s = bs->opaque;
Qcow2Bitmap *bm;
Qcow2BitmapList *bm_list;
if (s->nb_bitmaps == 0) {
/* Absence of the bitmap is not an error: see explanation above
* bdrv_remove_persistent_dirty_bitmap() definition. */
return;
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, errp);
if (bm_list == NULL) {
return;
}
bm = find_bitmap_by_name(bm_list, name);
if (bm == NULL) {
goto fail;
}
QSIMPLEQ_REMOVE(bm_list, bm, Qcow2Bitmap, entry);
ret = update_ext_header_and_dir(bs, bm_list);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to update bitmap extension");
goto fail;
}
free_bitmap_clusters(bs, &bm->table);
fail:
bitmap_free(bm);
bitmap_list_free(bm_list);
}
void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp)
{
BdrvDirtyBitmap *bitmap;
BDRVQcow2State *s = bs->opaque;
uint32_t new_nb_bitmaps = s->nb_bitmaps;
uint64_t new_dir_size = s->bitmap_directory_size;
int ret;
Qcow2BitmapList *bm_list;
Qcow2Bitmap *bm;
Qcow2BitmapTableList drop_tables;
Qcow2BitmapTable *tb, *tb_next;
if (!bdrv_has_changed_persistent_bitmaps(bs)) {
/* nothing to do */
return;
}
if (!can_write(bs)) {
error_setg(errp, "No write access");
return;
}
QSIMPLEQ_INIT(&drop_tables);
if (s->nb_bitmaps == 0) {
bm_list = bitmap_list_new();
} else {
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, errp);
if (bm_list == NULL) {
return;
}
}
/* check constraints and names */
for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap != NULL;
bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
{
const char *name = bdrv_dirty_bitmap_name(bitmap);
uint32_t granularity = bdrv_dirty_bitmap_granularity(bitmap);
Qcow2Bitmap *bm;
if (!bdrv_dirty_bitmap_get_persistance(bitmap) ||
bdrv_dirty_bitmap_readonly(bitmap))
{
continue;
}
if (check_constraints_on_bitmap(bs, name, granularity, errp) < 0) {
error_prepend(errp, "Bitmap '%s' doesn't satisfy the constraints: ",
name);
goto fail;
}
bm = find_bitmap_by_name(bm_list, name);
if (bm == NULL) {
if (++new_nb_bitmaps > QCOW2_MAX_BITMAPS) {
error_setg(errp, "Too many persistent bitmaps");
goto fail;
}
new_dir_size += calc_dir_entry_size(strlen(name), 0);
if (new_dir_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
error_setg(errp, "Bitmap directory is too large");
goto fail;
}
bm = g_new0(Qcow2Bitmap, 1);
bm->name = g_strdup(name);
QSIMPLEQ_INSERT_TAIL(bm_list, bm, entry);
} else {
if (!(bm->flags & BME_FLAG_IN_USE)) {
error_setg(errp, "Bitmap '%s' already exists in the image",
name);
goto fail;
}
tb = g_memdup(&bm->table, sizeof(bm->table));
bm->table.offset = 0;
bm->table.size = 0;
QSIMPLEQ_INSERT_TAIL(&drop_tables, tb, entry);
}
bm->flags = bdrv_dirty_bitmap_get_autoload(bitmap) ? BME_FLAG_AUTO : 0;
bm->granularity_bits = ctz32(bdrv_dirty_bitmap_granularity(bitmap));
bm->dirty_bitmap = bitmap;
}
/* allocate clusters and store bitmaps */
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
if (bm->dirty_bitmap == NULL) {
continue;
}
ret = store_bitmap(bs, bm, errp);
if (ret < 0) {
goto fail;
}
}
ret = update_ext_header_and_dir(bs, bm_list);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to update bitmap extension");
goto fail;
}
/* Bitmap directory was successfully updated, so, old data can be dropped.
* TODO it is better to reuse these clusters */
QSIMPLEQ_FOREACH_SAFE(tb, &drop_tables, entry, tb_next) {
free_bitmap_clusters(bs, tb);
g_free(tb);
}
bitmap_list_free(bm_list);
return;
fail:
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
if (bm->dirty_bitmap == NULL || bm->table.offset == 0) {
continue;
}
free_bitmap_clusters(bs, &bm->table);
}
QSIMPLEQ_FOREACH_SAFE(tb, &drop_tables, entry, tb_next) {
g_free(tb);
}
bitmap_list_free(bm_list);
}
int qcow2_reopen_bitmaps_ro(BlockDriverState *bs, Error **errp)
{
BdrvDirtyBitmap *bitmap;
Error *local_err = NULL;
qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
if (local_err != NULL) {
error_propagate(errp, local_err);
return -EINVAL;
}
for (bitmap = bdrv_dirty_bitmap_next(bs, NULL); bitmap != NULL;
bitmap = bdrv_dirty_bitmap_next(bs, bitmap))
{
if (bdrv_dirty_bitmap_get_persistance(bitmap)) {
bdrv_dirty_bitmap_set_readonly(bitmap, true);
}
}
return 0;
}
bool qcow2_can_store_new_dirty_bitmap(BlockDriverState *bs,
const char *name,
uint32_t granularity,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
bool found;
Qcow2BitmapList *bm_list;
if (s->qcow_version < 3) {
/* Without autoclear_features, we would always have to assume
* that a program without persistent dirty bitmap support has
* accessed this qcow2 file when opening it, and would thus
* have to drop all dirty bitmaps (defeating their purpose).
*/
error_setg(errp, "Cannot store dirty bitmaps in qcow2 v2 files");
goto fail;
}
if (check_constraints_on_bitmap(bs, name, granularity, errp) != 0) {
goto fail;
}
if (s->nb_bitmaps == 0) {
return true;
}
if (s->nb_bitmaps >= QCOW2_MAX_BITMAPS) {
error_setg(errp,
"Maximum number of persistent bitmaps is already reached");
goto fail;
}
if (s->bitmap_directory_size + calc_dir_entry_size(strlen(name), 0) >
QCOW2_MAX_BITMAP_DIRECTORY_SIZE)
{
error_setg(errp, "Not enough space in the bitmap directory");
goto fail;
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, errp);
if (bm_list == NULL) {
goto fail;
}
found = find_bitmap_by_name(bm_list, name);
bitmap_list_free(bm_list);
if (found) {
error_setg(errp, "Bitmap with the same name is already stored");
goto fail;
}
return true;
fail:
error_prepend(errp, "Can't make bitmap '%s' persistent in '%s': ",
name, bdrv_get_device_or_node_name(bs));
return false;
}
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