Only buffers that map to unallocated blocks need to be zeroed.
Signed-off-by: Christoph Hellwig h...@lst.de
---
block/sheepdog.c | 37 ++---
1 file changed, 18 insertions(+), 19 deletions(-)
Index: qemu/block/sheepdog.c
===
--- qemu.orig/block/sheepdog.c 2012-07-09 16:16:01.216467182 +0200
+++ qemu/block/sheepdog.c 2012-07-09 16:22:11.039798306 +0200
@@ -1556,18 +1556,25 @@ static int coroutine_fn sd_co_rw_vector(
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_skip(acb-qiov, 0, len, done);
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) {
@@ -1655,20 +1662,12 @@ static coroutine_fn int sd_co_readv(Bloc
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);
