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// SPDX-License-Identifier: GPL-2.0
/*
* virtio_pmem.c: Virtio pmem Driver
*
* Discovers persistent memory range information
* from host and provides a virtio based flushing
* interface.
*/
#include "virtio_pmem.h"
#include "nd.h"
/* The interrupt handler */
void virtio_pmem_host_ack(struct virtqueue *vq)
{
struct virtio_pmem *vpmem = vq->vdev->priv;
struct virtio_pmem_request *req_data, *req_buf;
unsigned long flags;
unsigned int len;
spin_lock_irqsave(&vpmem->pmem_lock, flags);
while ((req_data = virtqueue_get_buf(vq, &len)) != NULL) {
req_data->done = true;
wake_up(&req_data->host_acked);
if (!list_empty(&vpmem->req_list)) {
req_buf = list_first_entry(&vpmem->req_list,
struct virtio_pmem_request, list);
req_buf->wq_buf_avail = true;
wake_up(&req_buf->wq_buf);
list_del(&req_buf->list);
}
}
spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
}
EXPORT_SYMBOL_GPL(virtio_pmem_host_ack);
/* The request submission function */
static int virtio_pmem_flush(struct nd_region *nd_region)
{
struct virtio_device *vdev = nd_region->provider_data;
struct virtio_pmem *vpmem = vdev->priv;
struct virtio_pmem_request *req_data;
struct scatterlist *sgs[2], sg, ret;
unsigned long flags;
int err, err1;
might_sleep();
req_data = kmalloc(sizeof(*req_data), GFP_KERNEL);
if (!req_data)
return -ENOMEM;
req_data->done = false;
init_waitqueue_head(&req_data->host_acked);
init_waitqueue_head(&req_data->wq_buf);
INIT_LIST_HEAD(&req_data->list);
req_data->req.type = cpu_to_le32(VIRTIO_PMEM_REQ_TYPE_FLUSH);
sg_init_one(&sg, &req_data->req, sizeof(req_data->req));
sgs[0] = &sg;
sg_init_one(&ret, &req_data->resp.ret, sizeof(req_data->resp));
sgs[1] = &ret;
spin_lock_irqsave(&vpmem->pmem_lock, flags);
/*
* If virtqueue_add_sgs returns -ENOSPC then req_vq virtual
* queue does not have free descriptor. We add the request
* to req_list and wait for host_ack to wake us up when free
* slots are available.
*/
while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req_data,
GFP_ATOMIC)) == -ENOSPC) {
dev_info(&vdev->dev, "failed to send command to virtio pmem device, no free slots in the virtqueue\n");
req_data->wq_buf_avail = false;
list_add_tail(&req_data->list, &vpmem->req_list);
spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
/* A host response results in "host_ack" getting called */
wait_event(req_data->wq_buf, req_data->wq_buf_avail);
spin_lock_irqsave(&vpmem->pmem_lock, flags);
}
err1 = virtqueue_kick(vpmem->req_vq);
spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
/*
* virtqueue_add_sgs failed with error different than -ENOSPC, we can't
* do anything about that.
*/
if (err || !err1) {
dev_info(&vdev->dev, "failed to send command to virtio pmem device\n");
err = -EIO;
} else {
/* A host repsonse results in "host_ack" getting called */
wait_event(req_data->host_acked, req_data->done);
err = le32_to_cpu(req_data->resp.ret);
}
kfree(req_data);
return err;
};
/* The asynchronous flush callback function */
int async_pmem_flush(struct nd_region *nd_region, struct bio *bio)
{
/*
* Create child bio for asynchronous flush and chain with
* parent bio. Otherwise directly call nd_region flush.
*/
if (bio && bio->bi_iter.bi_sector != -1) {
struct bio *child = bio_alloc(bio->bi_bdev, 0,
REQ_OP_WRITE | REQ_PREFLUSH,
GFP_ATOMIC);
if (!child)
return -ENOMEM;
bio_clone_blkg_association(child, bio);
child->bi_iter.bi_sector = -1;
bio_chain(child, bio);
submit_bio(child);
return 0;
}
if (virtio_pmem_flush(nd_region))
return -EIO;
return 0;
};
EXPORT_SYMBOL_GPL(async_pmem_flush);
MODULE_DESCRIPTION("Virtio Persistent Memory Driver");
MODULE_LICENSE("GPL");
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