diff options
author | Jan Kiszka <jan.kiszka@siemens.com> | 2009-11-30 18:21:20 +0100 |
---|---|---|
committer | Anthony Liguori <aliguori@us.ibm.com> | 2009-12-03 10:48:52 -0600 |
commit | c6d2283068026035a6468aae9dcde953bd7521ac (patch) | |
tree | db0eef6fb2a061b09f7804239a8260e6b45b2df2 | |
parent | 6ea44308b0e8156d352f07b97b2b05eaed89aa6d (diff) | |
download | qemu-c6d2283068026035a6468aae9dcde953bd7521ac.zip qemu-c6d2283068026035a6468aae9dcde953bd7521ac.tar.gz qemu-c6d2283068026035a6468aae9dcde953bd7521ac.tar.bz2 |
block migration: Cleanup dirty tracking code
This switches the dirty bitmap to a true bitmap, reducing its footprint
(specifically in caches). It moreover fixes off-by-one bugs in
set_dirty_bitmap (nb_sectors+1 were marked) and bdrv_get_dirty (limit
check allowed one sector behind end of drive). And is drops redundant
dirty_tracking field from BlockDriverState.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
-rw-r--r-- | block.c | 44 | ||||
-rw-r--r-- | block_int.h | 3 |
2 files changed, 25 insertions, 22 deletions
@@ -642,12 +642,21 @@ 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) / BDRV_SECTORS_PER_DIRTY_CHUNK; + end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK; for (; start <= end; start++) { - bs->dirty_bitmap[start] = dirty; + idx = start / (sizeof(unsigned long) * 8); + bit = start % (sizeof(unsigned long) * 8); + val = bs->dirty_bitmap[idx]; + if (dirty) { + val |= 1 << bit; + } else { + val &= ~(1 << bit); + } + bs->dirty_bitmap[idx] = val; } } @@ -668,7 +677,7 @@ int bdrv_write(BlockDriverState *bs, int64_t sector_num, if (bdrv_check_request(bs, sector_num, nb_sectors)) return -EIO; - if (bs->dirty_tracking) { + if (bs->dirty_bitmap) { set_dirty_bitmap(bs, sector_num, nb_sectors, 1); } @@ -1218,7 +1227,7 @@ int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num, if (bdrv_check_request(bs, sector_num, nb_sectors)) return -EIO; - if (bs->dirty_tracking) { + if (bs->dirty_bitmap) { set_dirty_bitmap(bs, sector_num, nb_sectors, 1); } @@ -1419,7 +1428,7 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs, int64_t sector_num, if (bdrv_check_request(bs, sector_num, nb_sectors)) return NULL; - if (bs->dirty_tracking) { + if (bs->dirty_bitmap) { set_dirty_bitmap(bs, sector_num, nb_sectors, 1); } @@ -1965,23 +1974,17 @@ void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable) int64_t bitmap_size; if (enable) { - if (bs->dirty_tracking == 0) { - int64_t i; - uint8_t test; - - bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS); - bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK; - bitmap_size++; + if (!bs->dirty_bitmap) { + bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) + + BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1; + bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8; bs->dirty_bitmap = qemu_mallocz(bitmap_size); - - bs->dirty_tracking = enable; - for(i = 0; i < bitmap_size; i++) test = bs->dirty_bitmap[i]; } } else { - if (bs->dirty_tracking != 0) { + if (bs->dirty_bitmap) { qemu_free(bs->dirty_bitmap); - bs->dirty_tracking = enable; + bs->dirty_bitmap = NULL; } } } @@ -1990,9 +1993,10 @@ int bdrv_get_dirty(BlockDriverState *bs, int64_t sector) { int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK; - if (bs->dirty_bitmap != NULL && - (sector << BDRV_SECTOR_BITS) <= bdrv_getlength(bs)) { - return bs->dirty_bitmap[chunk]; + if (bs->dirty_bitmap && + (sector << BDRV_SECTOR_BITS) < bdrv_getlength(bs)) { + return bs->dirty_bitmap[chunk / (sizeof(unsigned long) * 8)] & + (1 << (chunk % (sizeof(unsigned long) * 8))); } else { return 0; } diff --git a/block_int.h b/block_int.h index 7ebe926..907e864 100644 --- a/block_int.h +++ b/block_int.h @@ -168,8 +168,7 @@ struct BlockDriverState { int cyls, heads, secs, translation; int type; char device_name[32]; - int dirty_tracking; - uint8_t *dirty_bitmap; + unsigned long *dirty_bitmap; BlockDriverState *next; void *private; }; |