diff options
| author | Peter Lieven <pl@dlhnet.de> | 2012-11-19 15:58:31 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2013-01-22 15:07:03 +0100 |
| commit | 4cc841b57c1dc91d71bafc25b53ffab4eff7959b (patch) | |
| tree | b70c91057c520fce8aba483f7b794706ff37a96b /block | |
| parent | de8864e5ae645fc22aa4ecf1999705c2dd5cf93c (diff) | |
| download | qemu-4cc841b57c1dc91d71bafc25b53ffab4eff7959b.zip qemu-4cc841b57c1dc91d71bafc25b53ffab4eff7959b.tar.gz qemu-4cc841b57c1dc91d71bafc25b53ffab4eff7959b.tar.bz2 | |
iscsi: partly avoid iovec linearization in iscsi_aio_writev
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>
Diffstat (limited to 'block')
| -rw-r--r-- | block/iscsi.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/block/iscsi.c b/block/iscsi.c index d8382fd..259192f 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -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, |