/*
* Block Dirty Bitmap
*
* Copyright (c) 2016 Red Hat. Inc
*
* 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-common.h"
#include "trace.h"
#include "block/block_int.h"
#include "block/blockjob.h"
/**
* A BdrvDirtyBitmap can be in three possible states:
* (1) successor is NULL and disabled is false: full r/w mode
* (2) successor is NULL and disabled is true: read only mode ("disabled")
* (3) successor is set: frozen mode.
* A frozen bitmap cannot be renamed, deleted, anonymized, cleared, set,
* or enabled. A frozen bitmap can only abdicate() or reclaim().
*/
struct BdrvDirtyBitmap {
HBitmap *bitmap; /* Dirty sector bitmap implementation */
BdrvDirtyBitmap *successor; /* Anonymous child; implies frozen status */
char *name; /* Optional non-empty unique ID */
int64_t size; /* Size of the bitmap (Number of sectors) */
bool disabled; /* Bitmap is read-only */
QLIST_ENTRY(BdrvDirtyBitmap) list;
};
BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs, const char *name)
{
BdrvDirtyBitmap *bm;
assert(name);
QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) {
if (bm->name && !strcmp(name, bm->name)) {
return bm;
}
}
return NULL;
}
void bdrv_dirty_bitmap_make_anon(BdrvDirtyBitmap *bitmap)
{
assert(!bdrv_dirty_bitmap_frozen(bitmap));
g_free(bitmap->name);
bitmap->name = NULL;
}
BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
uint32_t granularity,
const char *name,
Error **errp)
{
int64_t bitmap_size;
BdrvDirtyBitmap *bitmap;
uint32_t sector_granularity;
assert((granularity & (granularity - 1)) == 0);
if (name && bdrv_find_dirty_bitmap(bs, name)) {
error_setg(errp, "Bitmap already exists: %s", name);
return NULL;
}
sector_granularity = granularity >> BDRV_SECTOR_BITS;
assert(sector_granularity);
bitmap_size = bdrv_nb_sectors(bs);
if (bitmap_size < 0) {
error_setg_errno(errp, -bitmap_size, "could not get length of device");
errno = -bitmap_size;
return NULL;
}
bitmap = g_new0(BdrvDirtyBitmap, 1);
bitmap->bitmap = hbitmap_alloc(bitmap_size, ctz32(sector_granularity));
bitmap->size = bitmap_size;
bitmap->name = g_strdup(name);
bitmap->disabled = false;
QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
return bitmap;
}
bool bdrv_dirty_bitmap_frozen(BdrvDirtyBitmap *bitmap)
{
return bitmap->successor;
}
bool bdrv_dirty_bitmap_enabled(BdrvDirtyBitmap *bitmap)
{
return !(bitmap->disabled || bitmap->successor);
}
DirtyBitmapStatus bdrv_dirty_bitmap_status(BdrvDirtyBitmap *bitmap)
{
if (bdrv_dirty_bitmap_frozen(bitmap)) {
return DIRTY_BITMAP_STATUS_FROZEN;
} else if (!bdrv_dirty_bitmap_enabled(bitmap)) {
return DIRTY_BITMAP_STATUS_DISABLED;
} else {
return DIRTY_BITMAP_STATUS_ACTIVE;
}
}
/**
* Create a successor bitmap destined to replace this bitmap after an operation.
* Requires that the bitmap is not frozen and has no successor.
*/
int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
BdrvDirtyBitmap *bitmap, Error **errp)
{
uint64_t granularity;
BdrvDirtyBitmap *child;
if (bdrv_dirty_bitmap_frozen(bitmap)) {
error_setg(errp, "Cannot create a successor for a bitmap that is "
"currently frozen");
return -1;
}
assert(!bitmap->successor);
/* Create an anonymous successor */
granularity = bdrv_dirty_bitmap_granularity(bitmap);
child = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
if (!child) {
return -1;
}
/* Successor will be on or off based on our current state. */
child->disabled = bitmap->disabled;
/* Install the successor and freeze the parent */
bitmap->successor = child;
return 0;
}
/**
* For a bitmap with a successor, yield our name to the successor,
* delete the old bitmap, and return a handle to the new bitmap.
*/
BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs,
BdrvDirtyBitmap *bitmap,
Error **errp)
{
char *name;
BdrvDirtyBitmap *successor = bitmap->successor;
if (successor == NULL) {
error_setg(errp, "Cannot relinquish control if "
"there's no successor present");
return NULL;
}
name = bitmap->name;
bitmap->name = NULL;
successor->name = name;
bitmap->successor = NULL;
bdrv_release_dirty_bitmap(bs, bitmap);
return successor;
}
/**
* In cases of failure where we can no longer safely delete the parent,
* we may wish to re-join the parent and child/successor.
* The merged parent will be un-frozen, but not explicitly re-enabled.
*/
BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs,
BdrvDirtyBitmap *parent,
Error **errp)
{
BdrvDirtyBitmap *successor = parent->successor;
if (!successor) {
error_setg(errp, "Cannot reclaim a successor when none is present");
return NULL;
}
if (!hbitmap_merge(parent->bitmap, successor->bitmap)) {
error_setg(errp, "Merging of parent and successor bitmap failed");
return NULL;
}
bdrv_release_dirty_bitmap(bs, successor);
parent->successor = NULL;
return parent;
}
/**
* Truncates _all_ bitmaps attached to a BDS.
*/
void bdrv_dirty_bitmap_truncate(BlockDriverState *bs)
{
BdrvDirtyBitmap *bitmap;
uint64_t size = bdrv_nb_sectors(bs);
QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
assert(!bdrv_dirty_bitmap_frozen(bitmap));
hbitmap_truncate(bitmap->bitmap, size);
bitmap->size = size;
}
}
static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs,
BdrvDirtyBitmap *bitmap,
bool only_named)
{
BdrvDirtyBitmap *bm, *next;
QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
if ((!bitmap || bm == bitmap) && (!only_named || bm->name)) {
assert(!bdrv_dirty_bitmap_frozen(bm));
QLIST_REMOVE(bm, list);
hbitmap_free(bm->bitmap);
g_free(bm->name);
g_free(bm);
if (bitmap) {
return;
}
}
}
}
void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
{
bdrv_do_release_matching_dirty_bitmap(bs, bitmap, false);
}
/**
* Release all named dirty bitmaps attached to a BDS (for use in bdrv_close()).
* There must not be any frozen bitmaps attached.
*/
void bdrv_release_named_dirty_bitmaps(BlockDriverState *bs)
{
bdrv_do_release_matching_dirty_bitmap(bs, NULL, true);
}
void bdrv_disable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
{
assert(!bdrv_dirty_bitmap_frozen(bitmap));
bitmap->disabled = true;
}
void bdrv_enable_dirty_bitmap(BdrvDirtyBitmap *bitmap)
{
assert(!bdrv_dirty_bitmap_frozen(bitmap));
bitmap->disabled = false;
}
BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
{
BdrvDirtyBitmap *bm;
BlockDirtyInfoList *list = NULL;
BlockDirtyInfoList **plist = &list;
QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) {
BlockDirtyInfo *info = g_new0(BlockDirtyInfo, 1);
BlockDirtyInfoList *entry = g_new0(BlockDirtyInfoList, 1);
info->count = bdrv_get_dirty_count(bm);
info->granularity = bdrv_dirty_bitmap_granularity(bm);
info->has_name = !!bm->name;
info->name = g_strdup(bm->name);
info->status = bdrv_dirty_bitmap_status(bm);
entry->value = info;
*plist = entry;
plist = &entry->next;
}
return list;
}
int bdrv_get_dirty(BlockDriverState *bs, BdrvDirtyBitmap *bitmap,
int64_t sector)
{
if (bitmap) {
return hbitmap_get(bitmap->bitmap, sector);
} else {
return 0;
}
}
/**
* Chooses a default granularity based on the existing cluster size,
* but clamped between [4K, 64K]. Defaults to 64K in the case that there
* is no cluster size information available.
*/
uint32_t bdrv_get_default_bitmap_granularity(BlockDriverState *bs)
{
BlockDriverInfo bdi;
uint32_t granularity;
if (bdrv_get_info(bs, &bdi) >= 0 && bdi.cluster_size > 0) {
granularity = MAX(4096, bdi.cluster_size);
granularity = MIN(65536, granularity);
} else {
granularity = 65536;
}
return granularity;
}
uint32_t bdrv_dirty_bitmap_granularity(BdrvDirtyBitmap *bitmap)
{
return BDRV_SECTOR_SIZE << hbitmap_granularity(bitmap->bitmap);
}
void bdrv_dirty_iter_init(BdrvDirtyBitmap *bitmap, HBitmapIter *hbi)
{
hbitmap_iter_init(hbi, bitmap->bitmap, 0);
}
void bdrv_set_dirty_bitmap(BdrvDirtyBitmap *bitmap,
int64_t cur_sector, int nr_sectors)
{
assert(bdrv_dirty_bitmap_enabled(bitmap));
hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors);
}
void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
int64_t cur_sector, int nr_sectors)
{
assert(bdrv_dirty_bitmap_enabled(bitmap));
hbitmap_reset(bitmap->bitmap, cur_sector, nr_sectors);
}
void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap **out)
{
assert(bdrv_dirty_bitmap_enabled(bitmap));
if (!out) {
hbitmap_reset_all(bitmap->bitmap);
} else {
HBitmap *backup = bitmap->bitmap;
bitmap->bitmap = hbitmap_alloc(bitmap->size,
hbitmap_granularity(backup));
*out = backup;
}
}
void bdrv_undo_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap *in)
{
HBitmap *tmp = bitmap->bitmap;
assert(bdrv_dirty_bitmap_enabled(bitmap));
bitmap->bitmap = in;
hbitmap_free(tmp);
}
void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors)
{
BdrvDirtyBitmap *bitmap;
QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
if (!bdrv_dirty_bitmap_enabled(bitmap)) {
continue;
}
hbitmap_set(bitmap->bitmap, cur_sector, nr_sectors);
}
}
/**
* Advance an HBitmapIter to an arbitrary offset.
*/
void bdrv_set_dirty_iter(HBitmapIter *hbi, int64_t offset)
{
assert(hbi->hb);
hbitmap_iter_init(hbi, hbi->hb, offset);
}
int64_t bdrv_get_dirty_count(BdrvDirtyBitmap *bitmap)
{
return hbitmap_count(bitmap->bitmap);
}
