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iscsi: partly avoid iovec linearization in iscsi_aio_writev

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libiscsi expects all write16 data in a linear buffer. If the
iovec only contains one buffer we can skip the linearization
step as well as the additional malloc/free and pass the
buffer directly.

Reported-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Peter Lieven 2012-11-19 15:58:31 +01:00 committed by Paolo Bonzini
parent de8864e5ae
commit 4cc841b57c
1 changed files with 11 additions and 5 deletions
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16
block/iscsi.c
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@ -241,8 +241,17 @@ iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
/* XXX we should pass the iovec to write16 to avoid the extra copy */
/* this will allow us to get rid of 'buf' completely */
size = nb_sectors * BDRV_SECTOR_SIZE;
acb->buf = g_malloc(size);
qemu_iovec_to_buf(acb->qiov, 0, acb->buf, size);
data.size = MIN(size, acb->qiov->size);
/* if the iovec only contains one buffer we can pass it directly */
if (acb->qiov->niov == 1) {
acb->buf = NULL;
data.data = acb->qiov->iov[0].iov_base;
} else {
acb->buf = g_malloc(data.size);
qemu_iovec_to_buf(acb->qiov, 0, acb->buf, data.size);
data.data = acb->buf;
}
acb->task = malloc(sizeof(struct scsi_task));
if (acb->task == NULL) {
@ -263,9 +272,6 @@ iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
*(uint32_t *)&acb->task->cdb[10] = htonl(num_sectors);
acb->task->expxferlen = size;
data.data = acb->buf;
data.size = size;
if (iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
iscsi_aio_write16_cb,
&data,