qcow2: add persistent dirty bitmaps support

Store persistent dirty bitmaps in qcow2 image.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170628120530.31251-20-vsementsov@virtuozzo.com
[mreitz: Always assign ret in store_bitmap() in case of an error]
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2017-06-28 15:05:19 +03:00 committed by Max Reitz
parent 3dd10a06d1
commit 5f72826e7f
3 changed files with 486 additions and 0 deletions

View file

@ -27,6 +27,7 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/cutils.h"
#include "block/block_int.h"
#include "block/qcow2.h"
@ -42,6 +43,10 @@
#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)
@ -72,6 +77,8 @@ typedef struct Qcow2BitmapTable {
uint32_t size; /* number of 64bit entries */
QSIMPLEQ_ENTRY(Qcow2BitmapTable) entry;
} Qcow2BitmapTable;
typedef QSIMPLEQ_HEAD(Qcow2BitmapTableList, Qcow2BitmapTable)
Qcow2BitmapTableList;
typedef struct Qcow2Bitmap {
Qcow2BitmapTable table;
@ -79,6 +86,8 @@ typedef struct Qcow2Bitmap {
uint8_t granularity_bits;
char *name;
BdrvDirtyBitmap *dirty_bitmap;
QSIMPLEQ_ENTRY(Qcow2Bitmap) entry;
} Qcow2Bitmap;
typedef QSIMPLEQ_HEAD(Qcow2BitmapList, Qcow2Bitmap) Qcow2BitmapList;
@ -104,6 +113,15 @@ static int update_header_sync(BlockDriverState *bs)
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;
@ -127,6 +145,70 @@ static int check_table_entry(uint64_t entry, int cluster_size)
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)
{
@ -165,6 +247,28 @@ fail:
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;
}
/* This function returns the number of disk sectors covered by a single qcow2
* cluster of bitmap data. */
static uint64_t sectors_covered_by_bitmap_cluster(const BDRVQcow2State *s,
@ -748,6 +852,69 @@ static int update_ext_header_and_dir_in_place(BlockDriverState *bs,
*/
}
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)
@ -890,3 +1057,312 @@ out:
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 sector;
uint64_t sbc;
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, 0);
buf = g_malloc(s->cluster_size);
sbc = sectors_covered_by_bitmap_cluster(s, bitmap);
assert(DIV_ROUND_UP(bm_size, sbc) == tb_size);
while ((sector = bdrv_dirty_iter_next(dbi)) != -1) {
uint64_t cluster = sector / sbc;
uint64_t end, write_size;
int64_t off;
sector = cluster * sbc;
end = MIN(bm_size, sector + sbc);
write_size =
bdrv_dirty_bitmap_serialization_size(bitmap, sector, end - sector);
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, sector, end - sector);
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_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);
}

View file

@ -2046,6 +2046,7 @@ static int qcow2_inactivate(BlockDriverState *bs)
{
BDRVQcow2State *s = bs->opaque;
int ret, result = 0;
Error *local_err = NULL;
ret = qcow2_cache_flush(bs, s->l2_table_cache);
if (ret) {
@ -2061,6 +2062,14 @@ static int qcow2_inactivate(BlockDriverState *bs)
strerror(-ret));
}
qcow2_store_persistent_dirty_bitmaps(bs, &local_err);
if (local_err != NULL) {
result = -EINVAL;
error_report_err(local_err);
error_report("Persistent bitmaps are lost for node '%s'",
bdrv_get_device_or_node_name(bs));
}
if (result == 0) {
qcow2_mark_clean(bs);
}

View file

@ -647,5 +647,6 @@ int qcow2_check_bitmaps_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
int64_t *refcount_table_size);
bool qcow2_load_autoloading_dirty_bitmaps(BlockDriverState *bs, Error **errp);
int qcow2_reopen_bitmaps_rw(BlockDriverState *bs, Error **errp);
void qcow2_store_persistent_dirty_bitmaps(BlockDriverState *bs, Error **errp);
#endif