From 19db9b9042657ef80ddd4c94b1748dc2368aab70 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 10 Jul 2012 16:12:27 +0200 Subject: [PATCH] sheepdog: do not blindly memset all read buffers Only buffers that map to unallocated blocks need to be zeroed. Signed-off-by: Christoph Hellwig Acked-by: MORITA Kazutaka Signed-off-by: Kevin Wolf --- block/sheepdog.c | 37 ++++++++++++++++++------------------- 1 file changed, 18 insertions(+), 19 deletions(-) diff --git a/block/sheepdog.c b/block/sheepdog.c index 465dc97..a04ad99 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -1571,18 +1571,25 @@ static int coroutine_fn sd_co_rw_vector(void *p) len = MIN(total - done, SD_DATA_OBJ_SIZE - offset); - if (!inode->data_vdi_id[idx]) { - if (acb->aiocb_type == AIOCB_READ_UDATA) { + switch (acb->aiocb_type) { + case AIOCB_READ_UDATA: + if (!inode->data_vdi_id[idx]) { + qemu_iovec_memset(acb->qiov, done, 0, len); goto done; } - - create = 1; - } else if (acb->aiocb_type == AIOCB_WRITE_UDATA - && !is_data_obj_writable(inode, idx)) { - /* Copy-On-Write */ - create = 1; - old_oid = oid; - flags = SD_FLAG_CMD_COW; + break; + case AIOCB_WRITE_UDATA: + if (!inode->data_vdi_id[idx]) { + create = 1; + } else if (!is_data_obj_writable(inode, idx)) { + /* Copy-On-Write */ + create = 1; + old_oid = oid; + flags = SD_FLAG_CMD_COW; + } + break; + default: + break; } if (create) { @@ -1668,20 +1675,12 @@ static coroutine_fn int sd_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { SheepdogAIOCB *acb; - int i, ret; + int ret; acb = sd_aio_setup(bs, qiov, sector_num, nb_sectors, NULL, NULL); acb->aiocb_type = AIOCB_READ_UDATA; acb->aio_done_func = sd_finish_aiocb; - /* - * TODO: we can do better; we don't need to initialize - * blindly. - */ - for (i = 0; i < qiov->niov; i++) { - memset(qiov->iov[i].iov_base, 0, qiov->iov[i].iov_len); - } - ret = sd_co_rw_vector(acb); if (ret <= 0) { qemu_aio_release(acb); -- 2.7.4