Commit 7286d610 authored by Eric Blake's avatar Eric Blake Committed by Kevin Wolf
Browse files

block: Switch bdrv_make_zero() to byte-based 



We are gradually converting to byte-based interfaces, as they are
easier to reason about than sector-based.  Change the internal
loop iteration of zeroing a device to track by bytes instead of
sectors (although we are still guaranteed that we iterate by steps
that are sector-aligned).

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarJohn Snow <jsnow@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent f06f6b66

block/io.c

+16 −16
Original line number Diff line number Diff line
@@ -716,38 +716,38 @@ int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, 
 */

int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags)

{

    int64_t target_sectors, ret, nb_sectors, sector_num = 0;

    int64_t target_size, ret, bytes, offset = 0;

    BlockDriverState *bs = child->bs;

    int n;

    int n; /* sectors */



    target_sectors = bdrv_nb_sectors(bs);

    if (target_sectors < 0) {

        return target_sectors;

    target_size = bdrv_getlength(bs);

    if (target_size < 0) {

        return target_size;

    }



    for (;;) {

        nb_sectors = MIN(target_sectors - sector_num, BDRV_REQUEST_MAX_SECTORS);

        if (nb_sectors <= 0) {

        bytes = MIN(target_size - offset, BDRV_REQUEST_MAX_BYTES);

        if (bytes <= 0) {

            return 0;

        }

        ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, NULL);

        ret = bdrv_get_block_status(bs, offset >> BDRV_SECTOR_BITS,

                                    bytes >> BDRV_SECTOR_BITS, &n, NULL);

        if (ret < 0) {

            error_report("error getting block status at sector %" PRId64 ": %s",

                         sector_num, strerror(-ret));

            error_report("error getting block status at offset %" PRId64 ": %s",

                         offset, strerror(-ret));

            return ret;

        }

        if (ret & BDRV_BLOCK_ZERO) {

            sector_num += n;

            offset += n * BDRV_SECTOR_BITS;

            continue;

        }

        ret = bdrv_pwrite_zeroes(child, sector_num << BDRV_SECTOR_BITS,

                                 n << BDRV_SECTOR_BITS, flags);

        ret = bdrv_pwrite_zeroes(child, offset, n * BDRV_SECTOR_SIZE, flags);

        if (ret < 0) {

            error_report("error writing zeroes at sector %" PRId64 ": %s",

                         sector_num, strerror(-ret));

            error_report("error writing zeroes at offset %" PRId64 ": %s",

                         offset, strerror(-ret));

            return ret;

        }

        sector_num += n;

        offset += n * BDRV_SECTOR_SIZE;

    }

}