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block: implement dirty bitmap using HBitmap
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This actually uses the dirty bitmap in the block layer, and converts
mirroring to use an HBitmapIter.

Reviewed-by: Laszlo Ersek <[email protected]> (except block/mirror.c parts)
Reviewed-by: Eric Blake <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
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@bonzini @kevmw
bonzini authored and kevmw committed Jan 25, 2013
1 parent e7c033c commit 8f0720e
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Showing 5 changed files with 33 additions and 86 deletions.
96 changes: 16 additions & 80 deletions block.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1286,7 +1286,6 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
bs_dest->iostatus = bs_src->iostatus;

/* dirty bitmap */
bs_dest->dirty_count = bs_src->dirty_count;
bs_dest->dirty_bitmap = bs_src->dirty_bitmap;

/* job */
Expand Down Expand Up @@ -2035,36 +2034,6 @@ int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
return ret;
}

#define BITS_PER_LONG (sizeof(unsigned long) * 8)

static void set_dirty_bitmap(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int dirty)
{
int64_t start, end;
unsigned long val, idx, bit;

start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;

for (; start <= end; start++) {
idx = start / BITS_PER_LONG;
bit = start % BITS_PER_LONG;
val = bs->dirty_bitmap[idx];
if (dirty) {
if (!(val & (1UL << bit))) {
bs->dirty_count++;
val |= 1UL << bit;
}
} else {
if (val & (1UL << bit)) {
bs->dirty_count--;
val &= ~(1UL << bit);
}
}
bs->dirty_bitmap[idx] = val;
}
}

/* Return < 0 if error. Important errors are:
-EIO generic I/O error (may happen for all errors)
-ENOMEDIUM No media inserted.
Expand Down Expand Up @@ -4173,7 +4142,7 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
}

if (bs->dirty_bitmap) {
set_dirty_bitmap(bs, sector_num, nb_sectors, 0);
bdrv_reset_dirty(bs, sector_num, nb_sectors);
}

if (bs->drv->bdrv_co_discard) {
Expand Down Expand Up @@ -4335,86 +4304,53 @@ void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable)
{
int64_t bitmap_size;

bs->dirty_count = 0;
if (enable) {
if (!bs->dirty_bitmap) {
bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG - 1;
bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG;

bs->dirty_bitmap = g_new0(unsigned long, bitmap_size);
bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS);
bs->dirty_bitmap = hbitmap_alloc(bitmap_size,
BDRV_LOG_SECTORS_PER_DIRTY_CHUNK);
}
} else {
if (bs->dirty_bitmap) {
g_free(bs->dirty_bitmap);
hbitmap_free(bs->dirty_bitmap);
bs->dirty_bitmap = NULL;
}
}
}

int bdrv_get_dirty(BlockDriverState *bs, int64_t sector)
{
int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;

if (bs->dirty_bitmap &&
(sector << BDRV_SECTOR_BITS) < bdrv_getlength(bs)) {
return !!(bs->dirty_bitmap[chunk / BITS_PER_LONG] &
(1UL << (chunk % BITS_PER_LONG)));
if (bs->dirty_bitmap) {
return hbitmap_get(bs->dirty_bitmap, sector);
} else {
return 0;
}
}

int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector)
void bdrv_dirty_iter_init(BlockDriverState *bs, HBitmapIter *hbi)
{
int64_t chunk;
int bit, elem;

/* Avoid an infinite loop. */
assert(bs->dirty_count > 0);

sector = (sector | (BDRV_SECTORS_PER_DIRTY_CHUNK - 1)) + 1;
chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;

QEMU_BUILD_BUG_ON(sizeof(bs->dirty_bitmap[0]) * 8 != BITS_PER_LONG);
elem = chunk / BITS_PER_LONG;
bit = chunk % BITS_PER_LONG;
for (;;) {
if (sector >= bs->total_sectors) {
sector = 0;
bit = elem = 0;
}
if (bit == 0 && bs->dirty_bitmap[elem] == 0) {
sector += BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG;
elem++;
} else {
if (bs->dirty_bitmap[elem] & (1UL << bit)) {
return sector;
}
sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
if (++bit == BITS_PER_LONG) {
bit = 0;
elem++;
}
}
}
hbitmap_iter_init(hbi, bs->dirty_bitmap, 0);
}

void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors)
{
set_dirty_bitmap(bs, cur_sector, nr_sectors, 1);
hbitmap_set(bs->dirty_bitmap, cur_sector, nr_sectors);
}

void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors)
{
set_dirty_bitmap(bs, cur_sector, nr_sectors, 0);
hbitmap_reset(bs->dirty_bitmap, cur_sector, nr_sectors);
}

int64_t bdrv_get_dirty_count(BlockDriverState *bs)
{
return bs->dirty_count;
if (bs->dirty_bitmap) {
return hbitmap_count(bs->dirty_bitmap) >> BDRV_LOG_SECTORS_PER_DIRTY_CHUNK;
} else {
return 0;
}
}

void bdrv_set_in_use(BlockDriverState *bs, int in_use)
Expand Down
12 changes: 10 additions & 2 deletions block/mirror.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@ typedef struct MirrorBlockJob {
bool synced;
bool should_complete;
int64_t sector_num;
HBitmapIter hbi;
uint8_t *buf;
} MirrorBlockJob;

Expand All @@ -62,8 +63,15 @@ static int coroutine_fn mirror_iteration(MirrorBlockJob *s,
int64_t end;
struct iovec iov;

s->sector_num = hbitmap_iter_next(&s->hbi);
if (s->sector_num < 0) {
bdrv_dirty_iter_init(source, &s->hbi);
s->sector_num = hbitmap_iter_next(&s->hbi);
trace_mirror_restart_iter(s, bdrv_get_dirty_count(source));
assert(s->sector_num >= 0);
}

end = s->common.len >> BDRV_SECTOR_BITS;
s->sector_num = bdrv_get_next_dirty(source, s->sector_num);
nb_sectors = MIN(BDRV_SECTORS_PER_DIRTY_CHUNK, end - s->sector_num);
bdrv_reset_dirty(source, s->sector_num, nb_sectors);

Expand Down Expand Up @@ -136,7 +144,7 @@ static void coroutine_fn mirror_run(void *opaque)
}
}

s->sector_num = -1;
bdrv_dirty_iter_init(bs, &s->hbi);
for (;;) {
uint64_t delay_ns;
int64_t cnt;
Expand Down
6 changes: 4 additions & 2 deletions include/block/block.h
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Original file line number Diff line number Diff line change
Expand Up @@ -351,13 +351,15 @@ void bdrv_set_buffer_alignment(BlockDriverState *bs, int align);
void *qemu_blockalign(BlockDriverState *bs, size_t size);
bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov);

#define BDRV_SECTORS_PER_DIRTY_CHUNK 2048
#define BDRV_SECTORS_PER_DIRTY_CHUNK (1 << BDRV_LOG_SECTORS_PER_DIRTY_CHUNK)
#define BDRV_LOG_SECTORS_PER_DIRTY_CHUNK 11

struct HBitmapIter;
void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable);
int bdrv_get_dirty(BlockDriverState *bs, int64_t sector);
void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors);
void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors);
int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector);
void bdrv_dirty_iter_init(BlockDriverState *bs, struct HBitmapIter *hbi);
int64_t bdrv_get_dirty_count(BlockDriverState *bs);

void bdrv_enable_copy_on_read(BlockDriverState *bs);
Expand Down
4 changes: 2 additions & 2 deletions include/block/block_int.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#include "qapi-types.h"
#include "qapi/qmp/qerror.h"
#include "monitor/monitor.h"
#include "qemu/hbitmap.h"

#define BLOCK_FLAG_ENCRYPT 1
#define BLOCK_FLAG_COMPAT6 4
Expand Down Expand Up @@ -275,8 +276,7 @@ struct BlockDriverState {
bool iostatus_enabled;
BlockDeviceIoStatus iostatus;
char device_name[32];
unsigned long *dirty_bitmap;
int64_t dirty_count;
HBitmap *dirty_bitmap;
int in_use; /* users other than guest access, eg. block migration */
QTAILQ_ENTRY(BlockDriverState) list;

Expand Down
1 change: 1 addition & 0 deletions trace-events
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,7 @@ commit_start(void *bs, void *base, void *top, void *s, void *co, void *opaque) "

# block/mirror.c
mirror_start(void *bs, void *s, void *co, void *opaque) "bs %p s %p co %p opaque %p"
mirror_restart_iter(void *s, int64_t cnt) "s %p dirty count %"PRId64
mirror_before_flush(void *s) "s %p"
mirror_before_drain(void *s, int64_t cnt) "s %p dirty count %"PRId64
mirror_before_sleep(void *s, int64_t cnt, int synced) "s %p dirty count %"PRId64" synced %d"
Expand Down

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