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virtio-blk: simplify multiwrite calling conventions 

Pass the MultiReqBuffer structure down all the way to the I/O submission
instead of takin it apart.  Also mark num_writes unsigned as it can't
go negative, and take the check for any pending I/O requests into the
submission function.  Last but not least rename do_multiwrite to
virtio_submit_multiwrite to fit the general naming scheme and make clear
what it does.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Christoph Hellwig 2010-06-08 18:26:07 +02:00 committed by Anthony Liguori
parent 7e608e8903
commit c20fd87225
1 changed files with 35 additions and 37 deletions
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72
hw/virtio-blk.c
View File

@ -223,33 +223,39 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
}
#endif /* __linux__ */
static void do_multiwrite(BlockDriverState *bs, BlockRequest *blkreq,
int num_writes)
typedef struct MultiReqBuffer {
BlockRequest blkreq[32];
unsigned int num_writes;
} MultiReqBuffer;
static void virtio_submit_multiwrite(BlockDriverState *bs, MultiReqBuffer *mrb)
{
int i, ret;
ret = bdrv_aio_multiwrite(bs, blkreq, num_writes);
if (!mrb->num_writes) {
return;
}
ret = bdrv_aio_multiwrite(bs, mrb->blkreq, mrb->num_writes);
if (ret != 0) {
for (i = 0; i < num_writes; i++) {
if (blkreq[i].error) {
virtio_blk_rw_complete(blkreq[i].opaque, -EIO);
for (i = 0; i < mrb->num_writes; i++) {
if (mrb->blkreq[i].error) {
virtio_blk_rw_complete(mrb->blkreq[i].opaque, -EIO);
}
}
}
mrb->num_writes = 0;
}
static void virtio_blk_handle_flush(BlockRequest *blkreq, int *num_writes,
VirtIOBlockReq *req)
static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb)
{
BlockDriverAIOCB *acb;
/*
* Make sure all outstanding writes are posted to the backing device.
*/
if (*num_writes > 0) {
do_multiwrite(req->dev->bs, blkreq, *num_writes);
}
*num_writes = 0;
virtio_submit_multiwrite(req->dev->bs, mrb);
acb = bdrv_aio_flush(req->dev->bs, virtio_blk_flush_complete, req);
if (!acb) {
@ -257,27 +263,28 @@ static void virtio_blk_handle_flush(BlockRequest *blkreq, int *num_writes,
}
}
static void virtio_blk_handle_write(BlockRequest *blkreq, int *num_writes,
VirtIOBlockReq *req)
static void virtio_blk_handle_write(VirtIOBlockReq *req, MultiReqBuffer *mrb)
{
BlockRequest *blkreq;
if (req->out->sector & req->dev->sector_mask) {
virtio_blk_rw_complete(req, -EIO);
return;
}
if (*num_writes == 32) {
do_multiwrite(req->dev->bs, blkreq, *num_writes);
*num_writes = 0;
if (mrb->num_writes == 32) {
virtio_submit_multiwrite(req->dev->bs, mrb);
}
blkreq[*num_writes].sector = req->out->sector;
blkreq[*num_writes].nb_sectors = req->qiov.size / BDRV_SECTOR_SIZE;
blkreq[*num_writes].qiov = &req->qiov;
blkreq[*num_writes].cb = virtio_blk_rw_complete;
blkreq[*num_writes].opaque = req;
blkreq[*num_writes].error = 0;
blkreq = &mrb->blkreq[mrb->num_writes];
blkreq->sector = req->out->sector;
blkreq->nb_sectors = req->qiov.size / BDRV_SECTOR_SIZE;
blkreq->qiov = &req->qiov;
blkreq->cb = virtio_blk_rw_complete;
blkreq->opaque = req;
blkreq->error = 0;
(*num_writes)++;
mrb->num_writes++;
}
static void virtio_blk_handle_read(VirtIOBlockReq *req)
@ -297,11 +304,6 @@ static void virtio_blk_handle_read(VirtIOBlockReq *req)
}
}
typedef struct MultiReqBuffer {
BlockRequest blkreq[32];
int num_writes;
} MultiReqBuffer;
static void virtio_blk_handle_request(VirtIOBlockReq *req,
MultiReqBuffer *mrb)
{
@ -320,13 +322,13 @@ static void virtio_blk_handle_request(VirtIOBlockReq *req,
req->in = (void *)req->elem.in_sg[req->elem.in_num - 1].iov_base;
if (req->out->type & VIRTIO_BLK_T_FLUSH) {
virtio_blk_handle_flush(mrb->blkreq, &mrb->num_writes, req);
virtio_blk_handle_flush(req, mrb);
} else if (req->out->type & VIRTIO_BLK_T_SCSI_CMD) {
virtio_blk_handle_scsi(req);
} else if (req->out->type & VIRTIO_BLK_T_OUT) {
qemu_iovec_init_external(&req->qiov, &req->elem.out_sg[1],
req->elem.out_num - 1);
virtio_blk_handle_write(mrb->blkreq, &mrb->num_writes, req);
virtio_blk_handle_write(req, mrb);
} else {
qemu_iovec_init_external(&req->qiov, &req->elem.in_sg[0],
req->elem.in_num - 1);
@ -346,9 +348,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
virtio_blk_handle_request(req, &mrb);
}
if (mrb.num_writes > 0) {
do_multiwrite(s->bs, mrb.blkreq, mrb.num_writes);
}
virtio_submit_multiwrite(s->bs, &mrb);
/*
* FIXME: Want to check for completions before returning to guest mode,
@ -375,9 +375,7 @@ static void virtio_blk_dma_restart_bh(void *opaque)
req = req->next;
}
if (mrb.num_writes > 0) {
do_multiwrite(s->bs, mrb.blkreq, mrb.num_writes);
}
virtio_submit_multiwrite(s->bs, &mrb);
}
static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)