From: Pavel Butsykin <pbutsy...@virtuozzo.com> Added implementation of the qcow_co_pwritev_compressed function that will allow us to safely use compressed writes for the qcow from running VMs.
Signed-off-by: Pavel Butsykin <pbutsy...@virtuozzo.com> Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com> Signed-off-by: Denis V. Lunev <d...@openvz.org> CC: Jeff Cody <jc...@redhat.com> CC: Markus Armbruster <arm...@redhat.com> CC: Eric Blake <ebl...@redhat.com> CC: John Snow <js...@redhat.com> CC: Stefan Hajnoczi <stefa...@redhat.com> CC: Kevin Wolf <kw...@redhat.com> --- block/qcow.c | 109 +++++++++++++++++++++++------------------------------------ 1 file changed, 42 insertions(+), 67 deletions(-) diff --git a/block/qcow.c b/block/qcow.c index 0c7b75b..e1d335d 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -913,75 +913,42 @@ static int qcow_make_empty(BlockDriverState *bs) return 0; } -typedef struct QcowWriteCo { - BlockDriverState *bs; - int64_t sector_num; - const uint8_t *buf; - int nb_sectors; - int ret; -} QcowWriteCo; - -static void qcow_write_co_entry(void *opaque) -{ - QcowWriteCo *co = opaque; - QEMUIOVector qiov; - - struct iovec iov = (struct iovec) { - .iov_base = (uint8_t*) co->buf, - .iov_len = co->nb_sectors * BDRV_SECTOR_SIZE, - }; - qemu_iovec_init_external(&qiov, &iov, 1); - - co->ret = qcow_co_writev(co->bs, co->sector_num, co->nb_sectors, &qiov); -} - -/* Wrapper for non-coroutine contexts */ -static int qcow_write(BlockDriverState *bs, int64_t sector_num, - const uint8_t *buf, int nb_sectors) -{ - Coroutine *co; - AioContext *aio_context = bdrv_get_aio_context(bs); - QcowWriteCo data = { - .bs = bs, - .sector_num = sector_num, - .buf = buf, - .nb_sectors = nb_sectors, - .ret = -EINPROGRESS, - }; - co = qemu_coroutine_create(qcow_write_co_entry, &data); - qemu_coroutine_enter(co); - while (data.ret == -EINPROGRESS) { - aio_poll(aio_context, true); - } - return data.ret; -} - /* XXX: put compressed sectors first, then all the cluster aligned tables to avoid losing bytes in alignment */ -static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num, - const uint8_t *buf, int nb_sectors) +static coroutine_fn int +qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, + uint64_t bytes, QEMUIOVector *qiov) { BDRVQcowState *s = bs->opaque; + QEMUIOVector hd_qiov; + struct iovec iov; z_stream strm; int ret, out_len; - uint8_t *out_buf; + uint8_t *buf, *out_buf; uint64_t cluster_offset; - if (nb_sectors != s->cluster_sectors) { + if (bytes != s->cluster_size) { ret = -EINVAL; /* Zero-pad last write if image size is not cluster aligned */ - if (sector_num + nb_sectors == bs->total_sectors && - nb_sectors < s->cluster_sectors) { + if (offset + bytes == bs->total_sectors << BDRV_SECTOR_BITS && + bytes < s->cluster_size) + { uint8_t *pad_buf = qemu_blockalign(bs, s->cluster_size); memset(pad_buf, 0, s->cluster_size); - memcpy(pad_buf, buf, nb_sectors * BDRV_SECTOR_SIZE); - ret = qcow_write_compressed(bs, sector_num, - pad_buf, s->cluster_sectors); + qemu_iovec_to_buf(qiov, 0, pad_buf, s->cluster_size); + iov = (struct iovec) { + .iov_base = pad_buf, + .iov_len = s->cluster_size, + }; + qemu_iovec_init_external(&hd_qiov, &iov, 1); + ret = qcow_co_pwritev_compressed(bs, offset, bytes, &hd_qiov); qemu_vfree(pad_buf); } return ret; } + buf = qemu_blockalign(bs, s->cluster_size); + qemu_iovec_to_buf(qiov, 0, buf, qiov->size); out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); @@ -1012,27 +979,35 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num, if (ret != Z_STREAM_END || out_len >= s->cluster_size) { /* could not compress: write normal cluster */ - ret = qcow_write(bs, sector_num, buf, s->cluster_sectors); - if (ret < 0) { - goto fail; - } - } else { - cluster_offset = get_cluster_offset(bs, sector_num << 9, 2, - out_len, 0, 0); - if (cluster_offset == 0) { - ret = -EIO; - goto fail; - } - - cluster_offset &= s->cluster_offset_mask; - ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len); + ret = qcow_co_writev(bs, offset >> BDRV_SECTOR_BITS, + bytes >> BDRV_SECTOR_BITS, qiov); if (ret < 0) { goto fail; } + goto success; + } + qemu_co_mutex_lock(&s->lock); + cluster_offset = get_cluster_offset(bs, offset, 2, out_len, 0, 0); + qemu_co_mutex_unlock(&s->lock); + if (cluster_offset == 0) { + ret = -EIO; + goto fail; } + cluster_offset &= s->cluster_offset_mask; + iov = (struct iovec) { + .iov_base = out_buf, + .iov_len = out_len, + }; + qemu_iovec_init_external(&hd_qiov, &iov, 1); + ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0); + if (ret < 0) { + goto fail; + } +success: ret = 0; fail: + qemu_vfree(buf); g_free(out_buf); return ret; } @@ -1085,7 +1060,7 @@ static BlockDriver bdrv_qcow = { .bdrv_set_key = qcow_set_key, .bdrv_make_empty = qcow_make_empty, - .bdrv_write_compressed = qcow_write_compressed, + .bdrv_co_pwritev_compressed = qcow_co_pwritev_compressed, .bdrv_get_info = qcow_get_info, .create_opts = &qcow_create_opts, -- 2.5.0