Commit ab94db6f authored by Eric Blake's avatar Eric Blake Committed by Kevin Wolf
Browse files

qcow2: Switch load_bitmap_data() to byte-based iteration 



Now that we have adjusted the majority of the calls this function
makes to be byte-based, it is easier to read the code if it makes
passes over the image using bytes rather than sectors.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarJohn Snow <jsnow@redhat.com>
Reviewed-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent b85ee453

block/qcow2-bitmap.c

+8 −14
Original line number Diff line number Diff line
@@ -291,9 +291,8 @@ static int load_bitmap_data(BlockDriverState *bs, 
{

    int ret = 0;

    BDRVQcow2State *s = bs->opaque;

    uint64_t sector, limit, sbc;

    uint64_t offset, limit;

    uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap);

    uint64_t bm_sectors = DIV_ROUND_UP(bm_size, BDRV_SECTOR_SIZE);

    uint8_t *buf = NULL;

    uint64_t i, tab_size =

            size_to_clusters(s,
@@ -305,32 +304,27 @@ static int load_bitmap_data(BlockDriverState *bs, 


    buf = g_malloc(s->cluster_size);

    limit = bytes_covered_by_bitmap_cluster(s, bitmap);

    sbc = limit >> BDRV_SECTOR_BITS;

    for (i = 0, sector = 0; i < tab_size; ++i, sector += sbc) {

        uint64_t count = MIN(bm_sectors - sector, sbc);

    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 offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;

        uint64_t data_offset = entry & BME_TABLE_ENTRY_OFFSET_MASK;



        assert(check_table_entry(entry, s->cluster_size) == 0);



        if (offset == 0) {

        if (data_offset == 0) {

            if (entry & BME_TABLE_ENTRY_FLAG_ALL_ONES) {

                bdrv_dirty_bitmap_deserialize_ones(bitmap,

                                                   sector * BDRV_SECTOR_SIZE,

                                                   count * BDRV_SECTOR_SIZE,

                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, offset, buf, s->cluster_size);

            ret = bdrv_pread(bs->file, data_offset, buf, s->cluster_size);

            if (ret < 0) {

                goto finish;

            }

            bdrv_dirty_bitmap_deserialize_part(bitmap, buf,

                                               sector * BDRV_SECTOR_SIZE,

                                               count * BDRV_SECTOR_SIZE,

            bdrv_dirty_bitmap_deserialize_part(bitmap, buf, offset, count,

                                               false);

        }

    }