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iscsi: add support for iovectors 

This patch adds support for directly passing the iovec
array from QEMUIOVector if libiscsi supports it (1.8.0
or newer).

Signed-off-by: Peter Lieven <pl@kamp.de>
[Preserve the improvements from commit 4cc841b, iscsi: partly
 avoid iovec linearization in iscsi_aio_writev, 2012-11-19 - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Peter Lieven 2012-12-03 20:35:15 +01:00 committed by Paolo Bonzini
parent 4790b03d30
commit 7371d56fb2
1 changed files with 34 additions and 9 deletions
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43
block/iscsi.c
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@ -234,7 +234,10 @@ iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
size_t size;
uint32_t num_sectors;
uint64_t lba;
#if !defined(LIBISCSI_FEATURE_IOVECTOR)
struct iscsi_data data;
#endif
int ret;
acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
trace_iscsi_aio_writev(iscsi, sector_num, nb_sectors, opaque, acb);
@ -247,9 +250,10 @@ iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
acb->status = -EINPROGRESS;
acb->buf = NULL;
/* 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;
#if !defined(LIBISCSI_FEATURE_IOVECTOR)
data.size = MIN(size, acb->qiov->size);
/* if the iovec only contains one buffer we can pass it directly */
@ -260,6 +264,7 @@ iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
qemu_iovec_to_buf(acb->qiov, 0, acb->buf, data.size);
data.data = acb->buf;
}
#endif
acb->task = malloc(sizeof(struct scsi_task));
if (acb->task == NULL) {
@ -280,16 +285,28 @@ iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
*(uint32_t *)&acb->task->cdb[10] = htonl(num_sectors);
acb->task->expxferlen = size;
if (iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
iscsi_aio_write16_cb,
&data,
acb) != 0) {
#if defined(LIBISCSI_FEATURE_IOVECTOR)
ret = iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
iscsi_aio_write16_cb,
NULL,
acb);
#else
ret = iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
iscsi_aio_write16_cb,
&data,
acb);
#endif
if (ret != 0) {
scsi_free_scsi_task(acb->task);
g_free(acb->buf);
qemu_aio_release(acb);
return NULL;
}
#if defined(LIBISCSI_FEATURE_IOVECTOR)
scsi_task_set_iov_out(acb->task, (struct scsi_iovec*) acb->qiov->iov, acb->qiov->niov);
#endif
iscsi_set_events(iscsilun);
return &acb->common;
@ -327,7 +344,10 @@ iscsi_aio_readv(BlockDriverState *bs, int64_t sector_num,
struct iscsi_context *iscsi = iscsilun->iscsi;
IscsiAIOCB *acb;
size_t qemu_read_size;
#if !defined(LIBISCSI_FEATURE_IOVECTOR)
int i;
#endif
int ret;
uint64_t lba;
uint32_t num_sectors;
@ -389,20 +409,25 @@ iscsi_aio_readv(BlockDriverState *bs, int64_t sector_num,
break;
}
if (iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
iscsi_aio_read16_cb,
NULL,
acb) != 0) {
ret = iscsi_scsi_command_async(iscsi, iscsilun->lun, acb->task,
iscsi_aio_read16_cb,
NULL,
acb);
if (ret != 0) {
scsi_free_scsi_task(acb->task);
qemu_aio_release(acb);
return NULL;
}
#if defined(LIBISCSI_FEATURE_IOVECTOR)
scsi_task_set_iov_in(acb->task, (struct scsi_iovec*) acb->qiov->iov, acb->qiov->niov);
#else
for (i = 0; i < acb->qiov->niov; i++) {
scsi_task_add_data_in_buffer(acb->task,
acb->qiov->iov[i].iov_len,
acb->qiov->iov[i].iov_base);
}
#endif
iscsi_set_events(iscsilun);