Commit f24196d3 authored by Vladimir Sementsov-Ogievskiy's avatar Vladimir Sementsov-Ogievskiy Committed by Max Reitz
Browse files

qcow2: qcow2_co_preadv: improve locking 



Background: decryption will be done in threads, to take benefit of it,
we should move it out of the lock first.

But let's go further: it turns out, that only
qcow2_get_cluster_offset() needs locking, so reduce locking to it.

Signed-off-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190506142741.41731-7-vsementsov@virtuozzo.com
Reviewed-by: default avatarAlberto Garcia <berto@igalia.com>
Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
parent 6f13a316

block/qcow2.c

+2 −10
Original line number Diff line number Diff line
@@ -1969,8 +1969,6 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, 


    qemu_iovec_init(&hd_qiov, qiov->niov);



    qemu_co_mutex_lock(&s->lock);



    while (bytes != 0) {



        /* prepare next request */
@@ -1980,7 +1978,9 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, 
                            QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);

        }



        qemu_co_mutex_lock(&s->lock);

        ret = qcow2_get_cluster_offset(bs, offset, &cur_bytes, &cluster_offset);

        qemu_co_mutex_unlock(&s->lock);

        if (ret < 0) {

            goto fail;

        }
@@ -1995,10 +1995,8 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, 


            if (bs->backing) {

                BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);

                qemu_co_mutex_unlock(&s->lock);

                ret = bdrv_co_preadv(bs->backing, offset, cur_bytes,

                                     &hd_qiov, 0);

                qemu_co_mutex_lock(&s->lock);

                if (ret < 0) {

                    goto fail;

                }
@@ -2014,11 +2012,9 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, 
            break;



        case QCOW2_CLUSTER_COMPRESSED:

            qemu_co_mutex_unlock(&s->lock);

            ret = qcow2_co_preadv_compressed(bs, cluster_offset,

                                             offset, cur_bytes,

                                             &hd_qiov);

            qemu_co_mutex_lock(&s->lock);

            if (ret < 0) {

                goto fail;

            }
@@ -2055,11 +2051,9 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, 
            }



            BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);

            qemu_co_mutex_unlock(&s->lock);

            ret = bdrv_co_preadv(s->data_file,

                                 cluster_offset + offset_in_cluster,

                                 cur_bytes, &hd_qiov, 0);

            qemu_co_mutex_lock(&s->lock);

            if (ret < 0) {

                goto fail;

            }
@@ -2094,8 +2088,6 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset, 
    ret = 0;



fail:

    qemu_co_mutex_unlock(&s->lock);



    qemu_iovec_destroy(&hd_qiov);

    qemu_vfree(cluster_data);