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Date: Mon, 20 Apr 2020 15:19:47 +0200
From: Pankaj Gupta <pankaj.gupta.linux@...il.com>
To: linux-kernel@...r.kernel.org, linux-nvdimm@...ts.01.org
Cc: dan.j.williams@...el.com, vishal.l.verma@...el.com,
dave.jiang@...el.com, david@...hat.com, mst@...hat.com,
jmoyer@...hat.com, pankaj.gupta@...ud.ionos.com,
Pankaj Gupta <pankaj.gupta.linux@...il.com>
Subject: [RFC 2/2] virtio_pmem: Async virtio-pmem flush
This patch enables asynchronous flush for virtio pmem
using work queue. Also, it coalesce the flush requests
when a flush is already in process.
Signed-off-by: Pankaj Gupta <pankaj.gupta.linux@...il.com>
---
drivers/nvdimm/nd_virtio.c | 62 ++++++++++++++++++++++++++----------
drivers/nvdimm/virtio_pmem.c | 9 ++++++
drivers/nvdimm/virtio_pmem.h | 14 ++++++++
3 files changed, 68 insertions(+), 17 deletions(-)
diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c
index 10351d5b49fa..ef53d0a0d134 100644
--- a/drivers/nvdimm/nd_virtio.c
+++ b/drivers/nvdimm/nd_virtio.c
@@ -97,29 +97,57 @@ static int virtio_pmem_flush(struct nd_region *nd_region)
return err;
};
+static void submit_async_flush(struct work_struct *ws);
+
/* 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(GFP_ATOMIC, 0);
-
- if (!child)
- return -ENOMEM;
- bio_copy_dev(child, bio);
- child->bi_opf = REQ_PREFLUSH;
- child->bi_iter.bi_sector = -1;
- bio_chain(child, bio);
- submit_bio(child);
- return 0;
+ struct virtio_device *vdev = nd_region->provider_data;
+ struct virtio_pmem *vpmem = vdev->priv;
+ ktime_t start = ktime_get_boottime();
+
+ spin_lock_irq(&vpmem->lock);
+ wait_event_lock_irq(vpmem->sb_wait,
+ !vpmem->flush_bio ||
+ ktime_after(vpmem->last_flush, start),
+ vpmem->lock);
+
+ if (!ktime_after(vpmem->last_flush, start)) {
+ WARN_ON(vpmem->flush_bio);
+ vpmem->flush_bio = bio;
+ bio = NULL;
}
- if (virtio_pmem_flush(nd_region))
- return -EIO;
+ spin_unlock_irq(&vpmem->lock);
+ if (!bio) {
+ INIT_WORK(&vpmem->flush_work, submit_async_flush);
+ queue_work(vpmem->pmem_wq, &vpmem->flush_work);
+ return 1;
+ }
+
+ bio->bi_opf &= ~REQ_PREFLUSH;
return 0;
};
EXPORT_SYMBOL_GPL(async_pmem_flush);
+
+static void submit_async_flush(struct work_struct *ws)
+{
+ struct virtio_pmem *vpmem = container_of(ws, struct virtio_pmem, flush_work);
+ struct bio *bio = vpmem->flush_bio;
+
+ vpmem->start_flush = ktime_get_boottime();
+ bio->bi_status = errno_to_blk_status(virtio_pmem_flush(vpmem->nd_region));
+ vpmem->last_flush = vpmem->start_flush;
+ vpmem->flush_bio = NULL;
+ wake_up(&vpmem->sb_wait);
+
+ /* Submit parent bio only for PREFLUSH */
+ if (bio && (bio->bi_opf & REQ_PREFLUSH)) {
+ bio->bi_opf &= ~REQ_PREFLUSH;
+ submit_bio(bio);
+ } else if (bio && (bio->bi_opf & REQ_FUA)) {
+ bio->bi_opf &= ~REQ_FUA;
+ bio_endio(bio);
+ }
+}
MODULE_LICENSE("GPL");
diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c
index 5e3d07b47e0c..4ab135d820fd 100644
--- a/drivers/nvdimm/virtio_pmem.c
+++ b/drivers/nvdimm/virtio_pmem.c
@@ -24,6 +24,7 @@ static int init_vq(struct virtio_pmem *vpmem)
return PTR_ERR(vpmem->req_vq);
spin_lock_init(&vpmem->pmem_lock);
+ spin_lock_init(&vpmem->lock);
INIT_LIST_HEAD(&vpmem->req_list);
return 0;
@@ -58,6 +59,12 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
goto out_err;
}
+ vpmem->pmem_wq = alloc_workqueue("vpmem_wq", WQ_MEM_RECLAIM, 0);
+ if (!vpmem->pmem_wq) {
+ err = -ENOMEM;
+ goto out_err;
+ }
+ init_waitqueue_head(&vpmem->sb_wait);
virtio_cread(vpmem->vdev, struct virtio_pmem_config,
start, &vpmem->start);
virtio_cread(vpmem->vdev, struct virtio_pmem_config,
@@ -90,10 +97,12 @@ static int virtio_pmem_probe(struct virtio_device *vdev)
goto out_nd;
}
nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent);
+ vpmem->nd_region = nd_region;
return 0;
out_nd:
nvdimm_bus_unregister(vpmem->nvdimm_bus);
out_vq:
+ destroy_workqueue(vpmem->pmem_wq);
vdev->config->del_vqs(vdev);
out_err:
return err;
diff --git a/drivers/nvdimm/virtio_pmem.h b/drivers/nvdimm/virtio_pmem.h
index 0dddefe594c4..9d3615a324bf 100644
--- a/drivers/nvdimm/virtio_pmem.h
+++ b/drivers/nvdimm/virtio_pmem.h
@@ -35,9 +35,23 @@ struct virtio_pmem {
/* Virtio pmem request queue */
struct virtqueue *req_vq;
+ struct bio *flush_bio;
+ /* last_flush is when the last completed flush was started */
+ ktime_t last_flush, start_flush;
+
+ /* work queue for deferred flush */
+ struct work_struct flush_work;
+ struct workqueue_struct *pmem_wq;
+
+ /* Synchronize flush wait queue data */
+ spinlock_t lock;
+ /* for waiting for previous flush to complete */
+ wait_queue_head_t sb_wait;
+
/* nvdimm bus registers virtio pmem device */
struct nvdimm_bus *nvdimm_bus;
struct nvdimm_bus_descriptor nd_desc;
+ struct nd_region *nd_region;
/* List to store deferred work if virtqueue is full */
struct list_head req_list;
--
2.20.1
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