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qemu/block/qcow2-bitmap.c
Eric Blake ef893b5c84 block: Make it easier to learn which BDS support bitmaps 
Upcoming patches will enhance bitmap support in qemu-img, but in doing
so, it turns out to be nice to suppress output when persistent bitmaps
make no sense (such as on a qcow2 v2 image).  Add a hook to make this
easier to query.

This patch adds a new callback .bdrv_supports_persistent_dirty_bitmap,
rather than trying to shoehorn the answer in via existing callbacks.
In particular, while it might have been possible to overload
.bdrv_co_can_store_new_dirty_bitmap to special-case a NULL input to
answer whether any persistent bitmaps are supported, that is at odds
with whether a particular bitmap can be stored (for example, even on
an image that supports persistent bitmaps but has currently filled up
the maximum number of bitmaps, attempts to store another one should
fail); and the new functionality doesn't require coroutine safety.
Similarly, we could have added one more piece of information to
.bdrv_get_info, but then again, most callers to that function tend to
already discard extraneous information, and making it a catch-all
rather than a series of dedicated scalar queries hasn't really
simplified life.

In the future, when we improve the ability to look up bitmaps through
a filter, we will probably also want to teach the block layer to
automatically let filters pass this request on through.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200513011648.166876-4-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2020-05-19 10:32:14 -05:00

1757 lines
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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 "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
QEMU_BUILD_BUG_ON(BME_MAX_NAME_SIZE != BDRV_BITMAP_MAX_NAME_SIZE);
#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 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->file->bs);
}
static inline void bitmap_table_to_be(uint64_t *bitmap_table, size_t size)
{
size_t i;
for (i = 0; i < size; ++i) {
bitmap_table[i] = cpu_to_be64(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 int64_t get_bitmap_bytes_needed(int64_t len, uint32_t granularity)
{
int64_t num_bits = DIV_ROUND_UP(len, granularity);
return DIV_ROUND_UP(num_bits, 8);
}
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);
int64_t bitmap_bytes;
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;
}
bitmap_bytes = get_bitmap_bytes_needed(len, granularity);
if ((bitmap_bytes > (uint64_t)BME_MAX_PHYS_SIZE) ||
(bitmap_bytes > (uint64_t)BME_MAX_TABLE_SIZE * s->cluster_size))
{
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_ALWAYS);
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) {
table[i] = be64_to_cpu(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) {
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;
granularity = 1U << bm->granularity_bits;
bitmap = bdrv_create_dirty_bitmap(bs, granularity, bm->name, errp);
if (bitmap == NULL) {
goto fail;
}
if (bm->flags & BME_FLAG_IN_USE) {
/* Data is unusable, skip loading it */
return bitmap;
}
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;
}
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(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)
{
entry->bitmap_table_offset = be64_to_cpu(entry->bitmap_table_offset);
entry->bitmap_table_size = be32_to_cpu(entry->bitmap_table_size);
entry->flags = be32_to_cpu(entry->flags);
entry->name_size = be16_to_cpu(entry->name_size);
entry->extra_data_size = be32_to_cpu(entry->extra_data_size);
}
static inline void bitmap_dir_entry_to_be(Qcow2BitmapDirEntry *entry)
{
entry->bitmap_table_offset = cpu_to_be64(entry->bitmap_table_offset);
entry->bitmap_table_size = cpu_to_be32(entry->bitmap_table_size);
entry->flags = cpu_to_be32(entry->flags);
entry->name_size = cpu_to_be16(entry->name_size);
entry->extra_data_size = cpu_to_be32(entry->extra_data_size);
}
static inline int calc_dir_entry_size(size_t name_size, size_t extra_data_size)
{
int size = sizeof(Qcow2BitmapDirEntry) + name_size + extra_data_size;
return ROUND_UP(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;
}
if (phys_bitmap_bytes > BME_MAX_PHYS_SIZE) {
return -EINVAL;
}
if (!(entry->flags & BME_FLAG_IN_USE) &&
(len > ((phys_bitmap_bytes * 8) << entry->granularity_bits)))
{
/*
* We've loaded a valid bitmap (IN_USE not set) or we are going to
* store a valid bitmap, but the allocated bitmap table size is not
* enough to store this bitmap.
*
* Note, that it's OK to have an invalid bitmap with invalid size due
* to a bitmap that was not correctly saved after image resize.
*/
return -EINVAL;
}
return 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:
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_malloc0(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;
}
}
/* Actually, even in in-place case ignoring QCOW2_OL_BITMAP_DIRECTORY is not
* necessary, because we drop QCOW2_AUTOCLEAR_BITMAPS when updating bitmap
* directory in-place (actually, turn-off the extension), which is checked
* in qcow2_check_metadata_overlap() */
ret = qcow2_pre_write_overlap_check(
bs, in_place ? QCOW2_OL_BITMAP_DIRECTORY : 0, dir_offset, dir_size,
false);
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 = qcow2_flush_caches(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(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_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_dirty_bitmaps(BlockDriverState *bs, Error **errp)
{
BDRVQcow2State *s = bs->opaque;
Qcow2BitmapList *bm_list;
Qcow2Bitmap *bm;
GSList *created_dirty_bitmaps = NULL;
bool header_updated = false;
bool needs_update = 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) {
BdrvDirtyBitmap *bitmap;
if ((bm->flags & BME_FLAG_IN_USE) &&
bdrv_find_dirty_bitmap(bs, bm->name))
{
/*
* We already have corresponding BdrvDirtyBitmap, and bitmap in the
* image is marked IN_USE. Firstly, this state is valid, no reason
* to consider existing BdrvDirtyBitmap to be bad. Secondly it's
* absolutely possible, when we do migration with shared storage
* with dirty-bitmaps capability enabled: if the bitmap was loaded
* from this storage before migration start, the storage will
* of-course contain IN_USE outdated version of the bitmap, and we
* should not load it on migration target, as we already have this
* bitmap, being migrated.
*/
continue;
}
bitmap = load_bitmap(bs, bm, errp);
if (bitmap == NULL) {
goto fail;
}
bdrv_dirty_bitmap_set_persistence(bitmap, true);
if (bm->flags & BME_FLAG_IN_USE) {
bdrv_dirty_bitmap_set_inconsistent(bitmap);
} else {
/* NB: updated flags only get written if can_write(bs) is true. */
bm->flags |= BME_FLAG_IN_USE;
needs_update = true;
}
if (!(bm->flags & BME_FLAG_AUTO)) {
bdrv_disable_dirty_bitmap(bitmap);
}
created_dirty_bitmaps =
g_slist_append(created_dirty_bitmaps, bitmap);
}
if (needs_update && 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;
}
if (!can_write(bs)) {
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;
}
static Qcow2BitmapInfoFlagsList *get_bitmap_info_flags(uint32_t flags)
{
Qcow2BitmapInfoFlagsList *list = NULL;
Qcow2BitmapInfoFlagsList **plist = &list;
int i;
static const struct {
int bme; /* Bitmap directory entry flags */
int info; /* The flags to report to the user */
} map[] = {
{ BME_FLAG_IN_USE, QCOW2_BITMAP_INFO_FLAGS_IN_USE },
{ BME_FLAG_AUTO, QCOW2_BITMAP_INFO_FLAGS_AUTO },
};
int map_size = ARRAY_SIZE(map);
for (i = 0; i < map_size; ++i) {
if (flags & map[i].bme) {
Qcow2BitmapInfoFlagsList *entry =
g_new0(Qcow2BitmapInfoFlagsList, 1);
entry->value = map[i].info;
*plist = entry;
plist = &entry->next;
flags &= ~map[i].bme;
}
}
/* Check if the BME_* mapping above is complete */
assert(!flags);
return list;
}
/*
* qcow2_get_bitmap_info_list()
* Returns a list of QCOW2 bitmap details.
* In case of no bitmaps, the function returns NULL and
* the @errp parameter is not set.
* When bitmap information can not be obtained, the function returns
* NULL and the @errp parameter is set.
*/
Qcow2BitmapInfoList *qcow2_get_bitmap_info_list(BlockDriverState *bs,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
Qcow2BitmapList *bm_list;
Qcow2Bitmap *bm;
Qcow2BitmapInfoList *list = NULL;
Qcow2BitmapInfoList **plist = &list;
if (s->nb_bitmaps == 0) {
return NULL;
}
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, errp);
if (bm_list == NULL) {
return NULL;
}
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
Qcow2BitmapInfo *info = g_new0(Qcow2BitmapInfo, 1);
Qcow2BitmapInfoList *obj = g_new0(Qcow2BitmapInfoList, 1);
info->granularity = 1U << bm->granularity_bits;
info->name = g_strdup(bm->name);
info->flags = get_bitmap_info_flags(bm->flags & ~BME_RESERVED_FLAGS);
obj->value = info;
*plist = obj;
plist = &obj->next;
}
bitmap_list_free(bm_list);
return list;
}
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 = -EINVAL;
bool need_header_update = false;
if (s->nb_bitmaps == 0) {
/* No bitmaps - nothing to do */
return 0;
}
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) {
BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
if (!bitmap) {
error_setg(errp, "Unexpected bitmap '%s' in image '%s'",
bm->name, bs->filename);
goto out;
}
if (!(bm->flags & BME_FLAG_IN_USE)) {
if (!bdrv_dirty_bitmap_readonly(bitmap)) {
error_setg(errp, "Corruption: bitmap '%s' is not marked IN_USE "
"in the image '%s' and not marked readonly in RAM",
bm->name, bs->filename);
goto out;
}
if (bdrv_dirty_bitmap_inconsistent(bitmap)) {
error_setg(errp, "Corruption: bitmap '%s' is inconsistent but "
"is not marked IN_USE in the image '%s'", bm->name,
bs->filename);
goto out;
}
bm->flags |= BME_FLAG_IN_USE;
need_header_update = true;
} else {
/*
* What if flags already has BME_FLAG_IN_USE ?
*
* 1. if we are reopening RW -> RW it's OK, of course.
* 2. if we are reopening RO -> RW:
* 2.1 if @bitmap is inconsistent, it's OK. It means that it was
* inconsistent (IN_USE) when we loaded it
* 2.2 if @bitmap is not inconsistent. This seems to be impossible
* and implies third party interaction. Let's error-out for
* safety.
*/
if (bdrv_dirty_bitmap_readonly(bitmap) &&
!bdrv_dirty_bitmap_inconsistent(bitmap))
{
error_setg(errp, "Corruption: bitmap '%s' is marked IN_USE "
"in the image '%s' but it is readonly and "
"consistent in RAM",
bm->name, bs->filename);
goto out;
}
}
if (bdrv_dirty_bitmap_readonly(bitmap)) {
ro_dirty_bitmaps = g_slist_append(ro_dirty_bitmaps, bitmap);
}
}
if (need_header_update) {
if (!can_write(bs->file->bs) || !(bs->file->perm & BLK_PERM_WRITE)) {
error_setg(errp, "Failed to reopen bitmaps rw: no write access "
"the protocol file");
goto out;
}
/* 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, "Cannot update bitmap directory");
goto out;
}
}
g_slist_foreach(ro_dirty_bitmaps, set_readonly_helper, false);
ret = 0;
out:
g_slist_free(ro_dirty_bitmaps);
bitmap_list_free(bm_list);
return ret;
}
/* Checks to see if it's safe to resize bitmaps */
int qcow2_truncate_bitmaps_check(BlockDriverState *bs, Error **errp)
{
BDRVQcow2State *s = bs->opaque;
Qcow2BitmapList *bm_list;
Qcow2Bitmap *bm;
int ret = 0;
if (s->nb_bitmaps == 0) {
return 0;
}
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) {
BdrvDirtyBitmap *bitmap = bdrv_find_dirty_bitmap(bs, bm->name);
if (bitmap == NULL) {
/*
* We rely on all bitmaps being in-memory to be able to resize them,
* Otherwise, we'd need to resize them on disk explicitly
*/
error_setg(errp, "Cannot resize qcow2 with persistent bitmaps that "
"were not loaded into memory");
ret = -ENOTSUP;
goto out;
}
/*
* The checks against readonly and busy are redundant, but certainly
* do no harm. checks against inconsistent are crucial:
*/
if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) {
ret = -ENOTSUP;
goto out;
}
}
out:
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;
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;
}
buf = g_malloc(s->cluster_size);
limit = bytes_covered_by_bitmap_cluster(s, bitmap);
assert(DIV_ROUND_UP(bm_size, limit) == tb_size);
offset = 0;
while ((offset = bdrv_dirty_bitmap_next_dirty(bitmap, offset, INT64_MAX))
>= 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, false);
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;
}
offset = end;
}
*bitmap_table_size = tb_size;
g_free(buf);
return tb;
fail:
clear_bitmap_table(bs, tb, tb_size);
g_free(buf);
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]), false);
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;
}
int coroutine_fn qcow2_co_remove_persistent_dirty_bitmap(BlockDriverState *bs,
const char *name,
Error **errp)
{
int ret;
BDRVQcow2State *s = bs->opaque;
Qcow2Bitmap *bm = NULL;
Qcow2BitmapList *bm_list;
if (s->nb_bitmaps == 0) {
/*
* Absence of the bitmap is not an error: see explanation above
* bdrv_co_remove_persistent_dirty_bitmap() definition.
*/
return 0;
}
qemu_co_mutex_lock(&s->lock);
bm_list = bitmap_list_load(bs, s->bitmap_directory_offset,
s->bitmap_directory_size, errp);
if (bm_list == NULL) {
ret = -EIO;
goto out;
}
bm = find_bitmap_by_name(bm_list, name);
if (bm == NULL) {
/* Absence of the bitmap is not an error, see above. */
ret = 0;
goto out;
}
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 out;
}
free_bitmap_clusters(bs, &bm->table);
out:
qemu_co_mutex_unlock(&s->lock);
bitmap_free(bm);
bitmap_list_free(bm_list);
return ret;
}
/*
* qcow2_store_persistent_dirty_bitmaps
*
* Stores persistent BdrvDirtyBitmap objects.
*
* @release_stored: if true, release BdrvDirtyBitmap's after storing to the
* image. This is used in two cases, both via qcow2_inactivate:
* 1. bdrv_close: It's correct to remove bitmaps on close.
* 2. migration: If bitmaps are migrated through migration channel via
* 'dirty-bitmaps' migration capability they are not handled by this code.
* Otherwise, it's OK to drop BdrvDirtyBitmap's and reload them on
* invalidation.
*
* Anyway, it's correct to remove BdrvDirtyBitmap's on inactivation, as
* inactivation means that we lose control on disk, and therefore on bitmaps,
* we should sync them and do not touch more.
*
* Contrariwise, we don't want to release any bitmaps on just reopen-to-ro,
* when we need to store them, as image is still under our control, and it's
* good to keep all the bitmaps in read-only mode. Moreover, keeping them
* read-only is correct because this is what would happen if we opened the node
* readonly to begin with, and whether we opened directly or reopened to that
* state shouldn't matter for the state we get afterward.
*/
void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs,
bool release_stored, 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;
QSIMPLEQ_HEAD(, Qcow2BitmapTable) drop_tables;
Qcow2BitmapTable *tb, *tb_next;
bool need_write = false;
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_EACH_DIRTY_BITMAP(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_persistence(bitmap) ||
bdrv_dirty_bitmap_readonly(bitmap) ||
bdrv_dirty_bitmap_inconsistent(bitmap)) {
continue;
}
need_write = true;
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_enabled(bitmap) ? BME_FLAG_AUTO : 0;
bm->granularity_bits = ctz32(bdrv_dirty_bitmap_granularity(bitmap));
bm->dirty_bitmap = bitmap;
}
if (!need_write) {
goto success;
}
if (!can_write(bs)) {
error_setg(errp, "No write access");
goto fail;
}
/* 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);
}
if (release_stored) {
QSIMPLEQ_FOREACH(bm, bm_list, entry) {
if (bm->dirty_bitmap == NULL) {
continue;
}
bdrv_release_dirty_bitmap(bm->dirty_bitmap);
}
}
success:
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, false, &local_err);
if (local_err != NULL) {
error_propagate(errp, local_err);
return -EINVAL;
}
FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
if (bdrv_dirty_bitmap_get_persistence(bitmap)) {
bdrv_dirty_bitmap_set_readonly(bitmap, true);
}
}
return 0;
}
bool coroutine_fn qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
const char *name,
uint32_t granularity,
Error **errp)
{
BDRVQcow2State *s = bs->opaque;
BdrvDirtyBitmap *bitmap;
uint64_t bitmap_directory_size = 0;
uint32_t nb_bitmaps = 0;
if (bdrv_find_dirty_bitmap(bs, name)) {
error_setg(errp, "Bitmap already exists: %s", name);
return false;
}
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;
}
FOR_EACH_DIRTY_BITMAP(bs, bitmap) {
if (bdrv_dirty_bitmap_get_persistence(bitmap)) {
nb_bitmaps++;
bitmap_directory_size +=
calc_dir_entry_size(strlen(bdrv_dirty_bitmap_name(bitmap)), 0);
}
}
nb_bitmaps++;
bitmap_directory_size += calc_dir_entry_size(strlen(name), 0);
if (nb_bitmaps > QCOW2_MAX_BITMAPS) {
error_setg(errp,
"Maximum number of persistent bitmaps is already reached");
goto fail;
}
if (bitmap_directory_size > QCOW2_MAX_BITMAP_DIRECTORY_SIZE) {
error_setg(errp, "Not enough space in the bitmap directory");
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;
}
bool qcow2_supports_persistent_dirty_bitmap(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
return s->qcow_version >= 3;
}
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