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sheepdog: do not blindly memset all read buffers

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Only buffers that map to unallocated blocks need to be zeroed.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Christoph Hellwig 2012-07-10 16:12:27 +02:00 committed by Kevin Wolf
parent cddd4ac7a2
commit 19db9b9042
1 changed files with 18 additions and 19 deletions
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37
block/sheepdog.c
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@ -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);