Commit d1326a78 authored by Eric Blake's avatar Eric Blake Committed by Kevin Wolf
Browse files

qcow: Switch qcow_co_writev to byte-based calls 



We are gradually moving away from sector-based interfaces, towards
byte-based.  Make the change for the internals of the qcow
driver write function, by iterating over offset/bytes instead of
sector_num/nb_sectors, and with a rename of index_in_cluster and
repurposing of n to track bytes instead of sectors.

A later patch will then switch the qcow driver as a whole over
to byte-based operation.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarJeff Cody <jcody@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent a15312b0

block/qcow.c

+17 −19
Original line number Diff line number Diff line
@@ -723,13 +723,15 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, 
                                       int flags)

{

    BDRVQcowState *s = bs->opaque;

    int index_in_cluster;

    int offset_in_cluster;

    uint64_t cluster_offset;

    int ret = 0, n;

    struct iovec hd_iov;

    QEMUIOVector hd_qiov;

    uint8_t *buf;

    void *orig_buf;

    int64_t offset = sector_num * BDRV_SECTOR_SIZE;

    int64_t bytes = nb_sectors * BDRV_SECTOR_SIZE;



    assert(!flags);

    s->cluster_cache_offset = -1; /* disable compressed cache */
@@ -749,16 +751,14 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, 


    qemu_co_mutex_lock(&s->lock);



    while (nb_sectors != 0) {



        index_in_cluster = sector_num & (s->cluster_sectors - 1);

        n = s->cluster_sectors - index_in_cluster;

        if (n > nb_sectors) {

            n = nb_sectors;

    while (bytes != 0) {

        offset_in_cluster = offset & (s->cluster_size - 1);

        n = s->cluster_size - offset_in_cluster;

        if (n > bytes) {

            n = bytes;

        }

        ret = get_cluster_offset(bs, sector_num << 9, 1, 0,

                                 index_in_cluster << 9,

                                 (index_in_cluster + n) << 9, &cluster_offset);

        ret = get_cluster_offset(bs, offset, 1, 0, offset_in_cluster,

                                 offset_in_cluster + n, &cluster_offset);

        if (ret < 0) {

            break;

        }
@@ -768,30 +768,28 @@ static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t sector_num, 
        }

        if (bs->encrypted) {

            assert(s->crypto);

            if (qcrypto_block_encrypt(s->crypto, sector_num * BDRV_SECTOR_SIZE,

                                      buf, n * BDRV_SECTOR_SIZE, NULL) < 0) {

            if (qcrypto_block_encrypt(s->crypto, offset, buf, n, NULL) < 0) {

                ret = -EIO;

                break;

            }

        }



        hd_iov.iov_base = (void *)buf;

        hd_iov.iov_len = n * 512;

        hd_iov.iov_len = n;

        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);

        qemu_co_mutex_unlock(&s->lock);

        BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);

        ret = bdrv_co_writev(bs->file,

                             (cluster_offset >> 9) + index_in_cluster,

                             n, &hd_qiov);

        ret = bdrv_co_pwritev(bs->file, cluster_offset + offset_in_cluster,

                              n, &hd_qiov, 0);

        qemu_co_mutex_lock(&s->lock);

        if (ret < 0) {

            break;

        }

        ret = 0;



        nb_sectors -= n;

        sector_num += n;

        buf += n * 512;

        bytes -= n;

        offset += n;

        buf += n;

    }

    qemu_co_mutex_unlock(&s->lock);