> > > > Enable asynchronous flush for virtio pmem using work queue. Also, > > coalesce the flush requests when a flush is already in process. > > This functionality is copied from md/RAID code. > > > > When a flush is already in process, new flush requests wait till > > previous flush completes in another context (work queue). For all > > the requests come between ongoing flush and new flush start time, only > > single flush executes, thus adhers to flush coalscing logic. This is > > s/adhers/adheres/ > > s/coalscing/coalescing/ > > > important for maintaining the flush request order with request coalscing. > > s/coalscing/coalescing/
o.k. Sorry for the spelling mistakes. > > > > > Signed-off-by: Pankaj Gupta <pankaj.gupta.li...@gmail.com> > > --- > > drivers/nvdimm/nd_virtio.c | 74 +++++++++++++++++++++++++++--------- > > drivers/nvdimm/virtio_pmem.c | 10 +++++ > > drivers/nvdimm/virtio_pmem.h | 16 ++++++++ > > 3 files changed, 83 insertions(+), 17 deletions(-) > > > > diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c > > index 10351d5b49fa..179ea7a73338 100644 > > --- a/drivers/nvdimm/nd_virtio.c > > +++ b/drivers/nvdimm/nd_virtio.c > > @@ -100,26 +100,66 @@ static int virtio_pmem_flush(struct nd_region > > *nd_region) > > /* 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. > > + /* queue asynchronous flush and coalesce the flush requests */ > > + struct virtio_device *vdev = nd_region->provider_data; > > + struct virtio_pmem *vpmem = vdev->priv; > > + ktime_t req_start = ktime_get_boottime(); > > + int ret = -EINPROGRESS; > > + > > + spin_lock_irq(&vpmem->lock); > > Why a new lock and not continue to use ->pmem_lock? This spinlock is to protect entry in 'wait_event_lock_irq' and the Other spinlock is to protect virtio queue data. > > Have you tested this with CONFIG_PROVE_LOCKING? No, I only ran xfs tests and some of my unit test program. Will enable and test with CONFIG_PROVE_LOCKING. > > Along those lines do you have a selftest that can be added to the > kernel as well so that 0day or other bots could offer early warnings > on regressions? Will try to add one. Thank you Dan for the feedback! Best regards, Pankaj > > > + /* flush requests wait until ongoing flush completes, > > + * hence coalescing all the pending requests. > > */ > > - 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; > > + wait_event_lock_irq(vpmem->sb_wait, > > + !vpmem->flush_bio || > > + ktime_before(req_start, > > vpmem->prev_flush_start), > > + vpmem->lock); > > + /* new request after previous flush is completed */ > > + if (ktime_after(req_start, vpmem->prev_flush_start)) { > > + WARN_ON(vpmem->flush_bio); > > + vpmem->flush_bio = bio; > > + bio = NULL; > > + } > > + spin_unlock_irq(&vpmem->lock); > > + > > + if (!bio) > > + queue_work(vpmem->pmem_wq, &vpmem->flush_work); > > + else { > > + /* flush completed in other context while we waited */ > > + if (bio && (bio->bi_opf & REQ_PREFLUSH)) > > + bio->bi_opf &= ~REQ_PREFLUSH; > > + else if (bio && (bio->bi_opf & REQ_FUA)) > > + bio->bi_opf &= ~REQ_FUA; > > + > > + ret = vpmem->prev_flush_err; > > } > > - if (virtio_pmem_flush(nd_region)) > > - return -EIO; > > > > - return 0; > > + return ret; > > }; > > EXPORT_SYMBOL_GPL(async_pmem_flush); > > + > > +void submit_async_flush(struct work_struct *ws) > > This name is too generic to be exported from drivers/nvdimm/nd_virtio.c > > ...it strikes me that there is little reason for nd_virtio and > virtio_pmem to be separate modules. They are both enabled by the same > Kconfig, so why not combine them into one module and drop the exports? makes sense. > > > +{ > > + struct virtio_pmem *vpmem = container_of(ws, struct virtio_pmem, > > flush_work); > > + struct bio *bio = vpmem->flush_bio; > > + > > + vpmem->start_flush = ktime_get_boottime(); > > + vpmem->prev_flush_err = virtio_pmem_flush(vpmem->nd_region); > > + vpmem->prev_flush_start = vpmem->start_flush; > > + vpmem->flush_bio = NULL; > > + wake_up(&vpmem->sb_wait); > > + > > + if (vpmem->prev_flush_err) > > + bio->bi_status = errno_to_blk_status(-EIO); > > + > > + /* 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); > > + } > > +} > > +EXPORT_SYMBOL_GPL(submit_async_flush); > > MODULE_LICENSE("GPL"); > > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > > index 726c7354d465..75ed9b7ddea1 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; > > @@ -57,7 +58,14 @@ static int virtio_pmem_probe(struct virtio_device *vdev) > > dev_err(&vdev->dev, "failed to initialize virtio pmem > > vq's\n"); > > goto out_err; > > } > > + vpmem->pmem_wq = alloc_workqueue("vpmem_wq", WQ_MEM_RECLAIM, 0); > > + if (!vpmem->pmem_wq) { > > + err = -ENOMEM; > > + goto out_err; > > + } > > > > + INIT_WORK(&vpmem->flush_work, submit_async_flush); > > + init_waitqueue_head(&vpmem->sb_wait); > > virtio_cread_le(vpmem->vdev, struct virtio_pmem_config, > > start, &vpmem->start); > > virtio_cread_le(vpmem->vdev, struct virtio_pmem_config, > > @@ -90,10 +98,12 @@ 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..495dc20e1cdb 100644 > > --- a/drivers/nvdimm/virtio_pmem.h > > +++ b/drivers/nvdimm/virtio_pmem.h > > @@ -35,9 +35,24 @@ 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 prev_flush_start, start_flush; > > + int prev_flush_err; > > + > > + /* 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; > > @@ -52,4 +67,5 @@ struct virtio_pmem { > > > > void virtio_pmem_host_ack(struct virtqueue *vq); > > int async_pmem_flush(struct nd_region *nd_region, struct bio *bio); > > +void submit_async_flush(struct work_struct *ws); > > #endif > > -- > > 2.25.1 > > > >