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Date: Tue, 23 Apr 2024 15:27:29 +0800
From: Dongsheng Yang <dongsheng.yang@...ystack.cn>
To: dan.j.williams@...el.com, axboe@...nel.dk
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-cxl@...r.kernel.org, Dongsheng Yang <dongsheng.yang.linux@...il.com>
Subject: Re: [PATCH 6/7] cbd: introduce cbd_blkdev
在 2024/4/23 星期二 上午 6:42, Dongsheng Yang 写道:
> From: Dongsheng Yang <dongsheng.yang.linux@...il.com>
>
> The "cbd_blkdev" represents a virtual block device named "/dev/cbdX". It
> corresponds to a backend. The "blkdev" interacts with upper-layer users
> and accepts IO requests from them. A "blkdev" includes multiple
> "cbd_queues", each of which requires a "cbd_channel" to
> interact with the backend's handler. The "cbd_queue" forwards IO
> requests from the upper layer to the backend's handler through the
> channel.
>
> Signed-off-by: Dongsheng Yang <dongsheng.yang.linux@...il.com>
> ---
> drivers/block/cbd/Makefile | 2 +-
> drivers/block/cbd/cbd_blkdev.c | 375 ++++++++++++++++++
> drivers/block/cbd/cbd_main.c | 6 +
> drivers/block/cbd/cbd_queue.c | 621 ++++++++++++++++++++++++++++++
> drivers/block/cbd/cbd_transport.c | 11 +
> 5 files changed, 1014 insertions(+), 1 deletion(-)
> create mode 100644 drivers/block/cbd/cbd_blkdev.c
> create mode 100644 drivers/block/cbd/cbd_queue.c
>
> diff --git a/drivers/block/cbd/Makefile b/drivers/block/cbd/Makefile
> index b47f1e584946..f5fb5fd68f3d 100644
> --- a/drivers/block/cbd/Makefile
> +++ b/drivers/block/cbd/Makefile
> @@ -1,3 +1,3 @@
> -cbd-y := cbd_main.o cbd_transport.o cbd_channel.o cbd_host.o cbd_backend.o cbd_handler.o
> +cbd-y := cbd_main.o cbd_transport.o cbd_channel.o cbd_host.o cbd_backend.o cbd_handler.o cbd_blkdev.o cbd_queue.o
>
> obj-$(CONFIG_BLK_DEV_CBD) += cbd.o
> diff --git a/drivers/block/cbd/cbd_blkdev.c b/drivers/block/cbd/cbd_blkdev.c
> new file mode 100644
> index 000000000000..816bc28afb49
> --- /dev/null
> +++ b/drivers/block/cbd/cbd_blkdev.c
> @@ -0,0 +1,375 @@
> +#include "cbd_internal.h"
> +
> +static ssize_t blkdev_backend_id_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct cbd_blkdev_device *blkdev;
> + struct cbd_blkdev_info *blkdev_info;
> +
> + blkdev = container_of(dev, struct cbd_blkdev_device, dev);
> + blkdev_info = blkdev->blkdev_info;
> +
> + cbdt_flush_range(blkdev->cbdt, blkdev_info, sizeof(*blkdev_info));
> +
> + if (blkdev_info->state == cbd_blkdev_state_none)
> + return 0;
> +
> + return sprintf(buf, "%u\n", blkdev_info->backend_id);
> +}
> +
> +static DEVICE_ATTR(backend_id, 0400, blkdev_backend_id_show, NULL);
> +
> +static ssize_t blkdev_host_id_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct cbd_blkdev_device *blkdev;
> + struct cbd_blkdev_info *blkdev_info;
> +
> + blkdev = container_of(dev, struct cbd_blkdev_device, dev);
> + blkdev_info = blkdev->blkdev_info;
> +
> + cbdt_flush_range(blkdev->cbdt, blkdev_info, sizeof(*blkdev_info));
> +
> + if (blkdev_info->state == cbd_blkdev_state_none)
> + return 0;
> +
> + return sprintf(buf, "%u\n", blkdev_info->host_id);
> +}
> +
> +static DEVICE_ATTR(host_id, 0400, blkdev_host_id_show, NULL);
> +
> +static ssize_t blkdev_mapped_id_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct cbd_blkdev_device *blkdev;
> + struct cbd_blkdev_info *blkdev_info;
> +
> + blkdev = container_of(dev, struct cbd_blkdev_device, dev);
> + blkdev_info = blkdev->blkdev_info;
> +
> + cbdt_flush_range(blkdev->cbdt, blkdev_info, sizeof(*blkdev_info));
> +
> + if (blkdev_info->state == cbd_blkdev_state_none)
> + return 0;
> +
> + return sprintf(buf, "%u\n", blkdev_info->mapped_id);
> +}
> +
> +static DEVICE_ATTR(mapped_id, 0400, blkdev_mapped_id_show, NULL);
> +
> +CBD_OBJ_HEARTBEAT(blkdev);
> +
> +static struct attribute *cbd_blkdev_attrs[] = {
> + &dev_attr_mapped_id.attr,
> + &dev_attr_host_id.attr,
> + &dev_attr_backend_id.attr,
> + &dev_attr_alive.attr,
> + NULL
> +};
> +
> +static struct attribute_group cbd_blkdev_attr_group = {
> + .attrs = cbd_blkdev_attrs,
> +};
> +
> +static const struct attribute_group *cbd_blkdev_attr_groups[] = {
> + &cbd_blkdev_attr_group,
> + NULL
> +};
> +
> +static void cbd_blkdev_release(struct device *dev)
> +{
> +}
> +
> +struct device_type cbd_blkdev_type = {
> + .name = "cbd_blkdev",
> + .groups = cbd_blkdev_attr_groups,
> + .release = cbd_blkdev_release,
> +};
> +
> +struct device_type cbd_blkdevs_type = {
> + .name = "cbd_blkdevs",
> + .release = cbd_blkdev_release,
> +};
> +
> +
> +static int cbd_major;
> +static DEFINE_IDA(cbd_mapped_id_ida);
> +
> +static int minor_to_cbd_mapped_id(int minor)
> +{
> + return minor >> CBD_PART_SHIFT;
> +}
> +
> +
> +static int cbd_open(struct gendisk *disk, blk_mode_t mode)
> +{
> + return 0;
> +}
> +
> +static void cbd_release(struct gendisk *disk)
> +{
> +}
> +
> +static const struct block_device_operations cbd_bd_ops = {
> + .owner = THIS_MODULE,
> + .open = cbd_open,
> + .release = cbd_release,
> +};
> +
> +
> +static void cbd_blkdev_destroy_queues(struct cbd_blkdev *cbd_blkdev)
> +{
> + int i;
> +
> + for (i = 0; i < cbd_blkdev->num_queues; i++) {
> + cbd_queue_stop(&cbd_blkdev->queues[i]);
> + }
> +
> + kfree(cbd_blkdev->queues);
> +}
> +
> +static int cbd_blkdev_create_queues(struct cbd_blkdev *cbd_blkdev)
> +{
> + int i;
> + int ret;
> + struct cbd_queue *cbdq;
> +
> + cbd_blkdev->queues = kcalloc(cbd_blkdev->num_queues, sizeof(struct cbd_queue), GFP_KERNEL);
> + if (!cbd_blkdev->queues) {
> + return -ENOMEM;
> + }
> +
> + for (i = 0; i < cbd_blkdev->num_queues; i++) {
> + cbdq = &cbd_blkdev->queues[i];
> + cbdq->cbd_blkdev = cbd_blkdev;
> + cbdq->index = i;
> + ret = cbd_queue_start(cbdq);
> + if (ret)
> + goto err;
> +
> + }
> +
> + return 0;
> +err:
> + cbd_blkdev_destroy_queues(cbd_blkdev);
> + return ret;
> +}
> +
> +static int disk_start(struct cbd_blkdev *cbd_blkdev)
> +{
> + int ret;
> + struct gendisk *disk;
> +
> + memset(&cbd_blkdev->tag_set, 0, sizeof(cbd_blkdev->tag_set));
> + cbd_blkdev->tag_set.ops = &cbd_mq_ops;
> + cbd_blkdev->tag_set.queue_depth = 128;
> + cbd_blkdev->tag_set.numa_node = NUMA_NO_NODE;
> + cbd_blkdev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_NO_SCHED;
> + cbd_blkdev->tag_set.nr_hw_queues = cbd_blkdev->num_queues;
> + cbd_blkdev->tag_set.cmd_size = sizeof(struct cbd_request);
> + cbd_blkdev->tag_set.timeout = 0;
> + cbd_blkdev->tag_set.driver_data = cbd_blkdev;
> +
> + ret = blk_mq_alloc_tag_set(&cbd_blkdev->tag_set);
> + if (ret) {
> + pr_err("failed to alloc tag set %d", ret);
> + goto err;
> + }
> +
> + disk = blk_mq_alloc_disk(&cbd_blkdev->tag_set, cbd_blkdev);
> + if (IS_ERR(disk)) {
> + ret = PTR_ERR(disk);
> + pr_err("failed to alloc disk");
> + goto out_tag_set;
> + }
> +
> + snprintf(disk->disk_name, sizeof(disk->disk_name), "cbd%d",
> + cbd_blkdev->mapped_id);
> +
> + disk->major = cbd_major;
> + disk->first_minor = cbd_blkdev->mapped_id << CBD_PART_SHIFT;
> + disk->minors = (1 << CBD_PART_SHIFT);
> +
> + disk->fops = &cbd_bd_ops;
> + disk->private_data = cbd_blkdev;
> +
> + /* Tell the block layer that this is not a rotational device */
> + blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
> + blk_queue_flag_set(QUEUE_FLAG_SYNCHRONOUS, disk->queue);
> + blk_queue_flag_set(QUEUE_FLAG_NOWAIT, disk->queue);
> +
> + blk_queue_physical_block_size(disk->queue, PAGE_SIZE);
> + blk_queue_max_hw_sectors(disk->queue, 128);
> + blk_queue_max_segments(disk->queue, USHRT_MAX);
> + blk_queue_max_segment_size(disk->queue, UINT_MAX);
> + blk_queue_io_min(disk->queue, 4096);
> + blk_queue_io_opt(disk->queue, 4096);
> +
> + disk->queue->limits.max_sectors = queue_max_hw_sectors(disk->queue);
> + /* TODO support discard */
> + disk->queue->limits.discard_granularity = 0;
> + blk_queue_max_discard_sectors(disk->queue, 0);
> + blk_queue_max_write_zeroes_sectors(disk->queue, 0);
> +
> + cbd_blkdev->disk = disk;
> +
> + cbdt_add_blkdev(cbd_blkdev->cbdt, cbd_blkdev);
> + cbd_blkdev->blkdev_info->mapped_id = cbd_blkdev->blkdev_id;
> + cbd_blkdev->blkdev_info->state = cbd_blkdev_state_running;
> +
> + set_capacity(cbd_blkdev->disk, cbd_blkdev->dev_size);
> +
> + set_disk_ro(cbd_blkdev->disk, false);
> + blk_queue_write_cache(cbd_blkdev->disk->queue, false, false);
> +
> + ret = add_disk(cbd_blkdev->disk);
> + if (ret) {
> + goto put_disk;
> + }
> +
> + ret = sysfs_create_link(&disk_to_dev(cbd_blkdev->disk)->kobj,
> + &cbd_blkdev->blkdev_dev->dev.kobj, "cbd_blkdev");
> + if (ret) {
> + goto del_disk;
> + }
> +
> + blk_put_queue(cbd_blkdev->disk->queue);
> +
> + return 0;
> +
> +del_disk:
> + del_gendisk(cbd_blkdev->disk);
> +put_disk:
> + put_disk(cbd_blkdev->disk);
> +out_tag_set:
> + blk_mq_free_tag_set(&cbd_blkdev->tag_set);
> +err:
> + return ret;
> +}
> +
> +int cbd_blkdev_start(struct cbd_transport *cbdt, u32 backend_id, u32 queues)
> +{
> + struct cbd_blkdev *cbd_blkdev;
> + struct cbd_backend_info *backend_info;
> + u64 dev_size;
> + int ret;
> +
> + backend_info = cbdt_get_backend_info(cbdt, backend_id);
> + cbdt_flush_range(cbdt, backend_info, sizeof(*backend_info));
> + if (backend_info->blkdev_count == CBDB_BLKDEV_COUNT_MAX) {
> + return -EBUSY;
> + }
> +
> + dev_size = backend_info->dev_size;
> +
> + cbd_blkdev = kzalloc(sizeof(struct cbd_blkdev), GFP_KERNEL);
> + if (!cbd_blkdev) {
> + pr_err("fail to alloc cbd_blkdev");
> + return -ENOMEM;
> + }
> +
> + ret = cbdt_get_empty_blkdev_id(cbdt, &cbd_blkdev->blkdev_id);
> + if (ret < 0) {
> + goto blkdev_free;
> + }
> +
> + cbd_blkdev->mapped_id = ida_simple_get(&cbd_mapped_id_ida, 0,
> + minor_to_cbd_mapped_id(1 << MINORBITS),
> + GFP_KERNEL);
> + if (cbd_blkdev->mapped_id < 0) {
> + ret = -ENOENT;
> + goto blkdev_free;
> + }
> +
> + INIT_LIST_HEAD(&cbd_blkdev->node);
> + cbd_blkdev->cbdt = cbdt;
> + cbd_blkdev->backend_id = backend_id;
> + cbd_blkdev->num_queues = queues;
> + cbd_blkdev->dev_size = dev_size;
> + cbd_blkdev->blkdev_info = cbdt_get_blkdev_info(cbdt, cbd_blkdev->blkdev_id);
> + cbd_blkdev->blkdev_dev = &cbdt->cbd_blkdevs_dev->blkdev_devs[cbd_blkdev->blkdev_id];
> +
> + cbd_blkdev->blkdev_info->state = cbd_blkdev_state_running;
> + cbdt_flush_range(cbdt, cbd_blkdev->blkdev_info, sizeof(*cbd_blkdev->blkdev_info));
> +
> + INIT_DELAYED_WORK(&cbd_blkdev->hb_work, blkdev_hb_workfn);
> + queue_delayed_work(cbd_wq, &cbd_blkdev->hb_work, 0);
> +
> + ret = cbd_blkdev_create_queues(cbd_blkdev);
> + if (ret < 0) {
> + goto cancel_hb;;
> + }
> +
> + ret = disk_start(cbd_blkdev);
> + if (ret < 0) {
> + goto destroy_queues;
> + }
> +
> + backend_info->blkdev_count++;
> + cbdt_flush_range(cbdt, backend_info, sizeof(*backend_info));
> +
> + return 0;
> +
> +destroy_queues:
> + cbd_blkdev_destroy_queues(cbd_blkdev);
> +cancel_hb:
> + cancel_delayed_work_sync(&cbd_blkdev->hb_work);
> + cbd_blkdev->blkdev_info->state = cbd_blkdev_state_none;
> + cbdt_flush_range(cbdt, cbd_blkdev->blkdev_info, sizeof(*cbd_blkdev->blkdev_info));
> + ida_simple_remove(&cbd_mapped_id_ida, cbd_blkdev->mapped_id);
> +blkdev_free:
> + kfree(cbd_blkdev);
> + return ret;
> +}
> +
> +static void disk_stop(struct cbd_blkdev *cbd_blkdev)
> +{
> + sysfs_remove_link(&disk_to_dev(cbd_blkdev->disk)->kobj, "cache");
> + del_gendisk(cbd_blkdev->disk);
> + put_disk(cbd_blkdev->disk);
> + blk_mq_free_tag_set(&cbd_blkdev->tag_set);
> +}
> +
> +int cbd_blkdev_stop(struct cbd_transport *cbdt, u32 devid)
> +{
> + struct cbd_blkdev *cbd_blkdev;
> + struct cbd_backend_info *backend_info;
> +
> + cbd_blkdev = cbdt_fetch_blkdev(cbdt, devid);
> + if (!cbd_blkdev) {
> + return -EINVAL;
> + }
> +
> + backend_info = cbdt_get_backend_info(cbdt, cbd_blkdev->backend_id);
> +
> + disk_stop(cbd_blkdev);
> + cbd_blkdev_destroy_queues(cbd_blkdev);
> + cancel_delayed_work_sync(&cbd_blkdev->hb_work);
> + cbd_blkdev->blkdev_info->state = cbd_blkdev_state_none;
> + cbdt_flush_range(cbdt, cbd_blkdev->blkdev_info, sizeof(*cbd_blkdev->blkdev_info));
> + ida_simple_remove(&cbd_mapped_id_ida, cbd_blkdev->mapped_id);
> +
> + kfree(cbd_blkdev);
> +
> + backend_info->blkdev_count--;
> + cbdt_flush_range(cbdt, backend_info, sizeof(*backend_info));
> +
> + return 0;
> +}
> +
> +int cbd_blkdev_init(void)
> +{
> + cbd_major = register_blkdev(0, "cbd");
> + if (cbd_major < 0)
> + return cbd_major;
> +
> + return 0;
> +}
> +
> +void cbd_blkdev_exit(void)
> +{
> + unregister_blkdev(cbd_major, "cbd");
> +}
> diff --git a/drivers/block/cbd/cbd_main.c b/drivers/block/cbd/cbd_main.c
> index 8cfa60dde7c5..658233807b59 100644
> --- a/drivers/block/cbd/cbd_main.c
> +++ b/drivers/block/cbd/cbd_main.c
> @@ -195,6 +195,11 @@ static int __init cbd_init(void)
> goto device_unregister;
> }
>
> + ret = cbd_blkdev_init();
> + if (ret < 0) {
> + goto bus_unregister;
> + }
> +
> return 0;
>
> bus_unregister:
> @@ -209,6 +214,7 @@ static int __init cbd_init(void)
>
> static void cbd_exit(void)
> {
> + cbd_blkdev_exit();
> bus_unregister(&cbd_bus_type);
> device_unregister(&cbd_root_dev);
>
> diff --git a/drivers/block/cbd/cbd_queue.c b/drivers/block/cbd/cbd_queue.c
> new file mode 100644
> index 000000000000..6709ac016e18
> --- /dev/null
> +++ b/drivers/block/cbd/cbd_queue.c
> @@ -0,0 +1,621 @@
> +#include "cbd_internal.h"
> +
> +/*
> + * How do blkdev and backend interact through the channel?
> + * a) For reader side, before reading the data, if the data in this channel may
> + * be modified by the other party, then I need to flush the cache before reading to ensure
> + * that I get the latest data. For example, the blkdev needs to flush the cache before
> + * obtaining compr_head because compr_head will be updated by the backend handler.
> + * b) For writter side, if the written information will be read by others, then
> + * after writing, I need to flush the cache to let the other party see it immediately.
> + * For example, after blkdev submits cbd_se, it needs to update cmd_head to let the
> + * handler have a new cbd_se. Therefore, after updating cmd_head, I need to flush the
> + * cache to let the backend see it.
> + *
> + * For the blkdev queue, I am the only one who updates the `cmd_head`, `cmd_tail`, and `compr_tail'.
> + * Therefore, I don't need to flush_dcache before reading these data. However, after updating these data,
> + * I need to flush_dcache so that the backend handler can see these updates.
> + *
> + * On the other hand, `compr_head` is updated by the backend handler. So, I need to flush_dcache before
> + * reading `compr_head` to ensure that I can see the updates.
> + *
> + * ┌───────────┐ ┌─────────────┐
> + * │ blkdev │ │ backend │
> + * │ queue │ │ handler │
> + * └─────┬─────┘ └──────┬──────┘
> + * ▼ │
> + * init data and cbd_se │
> + * │ │
> + * ▼ │
> + * update cmd_head │
> + * │ │
> + * ▼ │
> + * flush_cache │
> + * │ ▼
> + * │ flush_cache
> + * │ │
> + * │ ▼
> + * │ handle cmd
> + * │ │
> + * │ ▼
> + * │ fill cbd_ce
> + * │ │
> + * │ ▼
> + * │ flush_cache
> + * ▼
> + * flush_cache
> + * │
> + * ▼
> + * complete_req
> + */
> +
> +static inline struct cbd_se *get_submit_entry(struct cbd_queue *cbdq)
> +{
> + return (struct cbd_se *)(cbdq->channel.cmdr + cbdq->channel_info->cmd_head);
> +}
> +
> +static inline struct cbd_se *get_oldest_se(struct cbd_queue *cbdq)
> +{
> + if (cbdq->channel_info->cmd_tail == cbdq->channel_info->cmd_head)
> + return NULL;
> +
> + return (struct cbd_se *)(cbdq->channel.cmdr + cbdq->channel_info->cmd_tail);
> +}
> +
> +static inline struct cbd_ce *get_complete_entry(struct cbd_queue *cbdq)
> +{
> + if (cbdq->channel_info->compr_tail == cbdq->channel_info->compr_head)
> + return NULL;
> +
> + return (struct cbd_ce *)(cbdq->channel.compr + cbdq->channel_info->compr_tail);
> +}
> +
> +static void cbd_req_init(struct cbd_queue *cbdq, enum cbd_op op, struct request *rq)
> +{
> + struct cbd_request *cbd_req = blk_mq_rq_to_pdu(rq);
> +
> + cbd_req->req = rq;
> + cbd_req->cbdq = cbdq;
> + cbd_req->op = op;
> +
> + return;
> +}
> +
> +static bool cbd_req_nodata(struct cbd_request *cbd_req)
> +{
> + switch (cbd_req->op) {
> + case CBD_OP_WRITE:
> + case CBD_OP_READ:
> + return false;
> + case CBD_OP_DISCARD:
> + case CBD_OP_WRITE_ZEROS:
> + case CBD_OP_FLUSH:
> + return true;
> + default:
> + BUG();
> + }
> +}
> +
> +static uint32_t cbd_req_segments(struct cbd_request *cbd_req)
> +{
> + uint32_t segs = 0;
> + struct bio *bio = cbd_req->req->bio;
> +
> + if (cbd_req_nodata(cbd_req))
> + return 0;
> +
> + while (bio) {
> + segs += bio_segments(bio);
> + bio = bio->bi_next;
> + }
> +
> + return segs;
> +}
> +
> +static inline size_t cbd_get_cmd_size(struct cbd_request *cbd_req)
> +{
> + u32 segs = cbd_req_segments(cbd_req);
> + u32 cmd_size = sizeof(struct cbd_se) + (sizeof(struct iovec) * segs);
> +
> + return round_up(cmd_size, CBD_OP_ALIGN_SIZE);
> +}
> +
> +static void insert_padding(struct cbd_queue *cbdq, u32 cmd_size)
> +{
> + struct cbd_se_hdr *header;
> + u32 pad_len;
> +
> + if (cbdq->channel_info->cmdr_size - cbdq->channel_info->cmd_head >= cmd_size)
> + return;
> +
> + pad_len = cbdq->channel_info->cmdr_size - cbdq->channel_info->cmd_head;
> + cbd_queue_debug(cbdq, "insert pad:%d\n", pad_len);
> +
> + header = (struct cbd_se_hdr *)get_submit_entry(cbdq);
> + memset(header, 0, pad_len);
> + cbd_se_hdr_set_op(&header->len_op, CBD_OP_PAD);
> + cbd_se_hdr_set_len(&header->len_op, pad_len);
> +
> + cbdt_flush_range(cbdq->cbd_blkdev->cbdt, header, sizeof(*header));
> +
> + CBDC_UPDATE_CMDR_HEAD(cbdq->channel_info->cmd_head, pad_len, cbdq->channel_info->cmdr_size);
> +}
> +
> +static void queue_req_se_init(struct cbd_request *cbd_req)
> +{
> + struct cbd_se *se;
> + struct cbd_se_hdr *header;
> + u64 offset = (u64)blk_rq_pos(cbd_req->req) << SECTOR_SHIFT;
> + u64 length = blk_rq_bytes(cbd_req->req);
> +
> + se = get_submit_entry(cbd_req->cbdq);
> + memset(se, 0, cbd_get_cmd_size(cbd_req));
> + header = &se->header;
> +
> + cbd_se_hdr_set_op(&header->len_op, cbd_req->op);
> + cbd_se_hdr_set_len(&header->len_op, cbd_get_cmd_size(cbd_req));
> +
> + se->priv_data = cbd_req->req_tid;
> + se->offset = offset;
> + se->len = length;
> +
> + if (req_op(cbd_req->req) == REQ_OP_READ || req_op(cbd_req->req) == REQ_OP_WRITE) {
> + se->data_off = cbd_req->cbdq->channel.data_head;
> + se->data_len = length;
> + }
> +
> + cbd_req->se = se;
> +}
> +
> +static bool data_space_enough(struct cbd_queue *cbdq, struct cbd_request *cbd_req)
> +{
> + u32 space_available;
> + u32 space_needed;
> + u32 space_used;
> + u32 space_max;
> +
> + space_max = cbdq->channel.data_size - 4096;
> +
> + if (cbdq->channel.data_head > cbdq->channel.data_tail)
> + space_used = cbdq->channel.data_head - cbdq->channel.data_tail;
> + else if (cbdq->channel.data_head < cbdq->channel.data_tail)
> + space_used = cbdq->channel.data_head + (cbdq->channel.data_size - cbdq->channel.data_tail);
> + else
> + space_used = 0;
> +
> + space_available = space_max - space_used;
> +
> + space_needed = round_up(cbd_req->data_len, 4096);
> +
> + if (space_available < space_needed) {
> + cbd_queue_err(cbdq, "data space is not enough: availaible: %u needed: %u",
> + space_available, space_needed);
> + return false;
> + }
> +
> + return true;
> +}
> +
> +static bool submit_ring_space_enough(struct cbd_queue *cbdq, u32 cmd_size)
> +{
> + u32 space_available;
> + u32 space_needed;
> + u32 space_max, space_used;
> +
> + /* There is a CMDR_RESERVED we dont use to prevent the ring to be used up */
> + space_max = cbdq->channel_info->cmdr_size - CBDC_CMDR_RESERVED;
> +
> + if (cbdq->channel_info->cmd_head > cbdq->channel_info->cmd_tail)
> + space_used = cbdq->channel_info->cmd_head - cbdq->channel_info->cmd_tail;
> + else if (cbdq->channel_info->cmd_head < cbdq->channel_info->cmd_tail)
> + space_used = cbdq->channel_info->cmd_head + (cbdq->channel_info->cmdr_size - cbdq->channel_info->cmd_tail);
> + else
> + space_used = 0;
> +
> + space_available = space_max - space_used;
> +
> + if (cbdq->channel_info->cmdr_size - cbdq->channel_info->cmd_head > cmd_size)
> + space_needed = cmd_size;
> + else
> + space_needed = cmd_size + cbdq->channel_info->cmdr_size - cbdq->channel_info->cmd_head;
> +
> + if (space_available < space_needed)
> + return false;
> +
> + return true;
> +}
> +
> +static void queue_req_data_init(struct cbd_request *cbd_req)
> +{
> + struct cbd_queue *cbdq = cbd_req->cbdq;
> + struct bio *bio = cbd_req->req->bio;
> +
> + if (cbd_req->op == CBD_OP_READ) {
> + goto advance_data_head;
> + }
> +
> + cbdc_copy_from_bio(&cbdq->channel, cbd_req->data_off, cbd_req->data_len, bio);
> +
> +advance_data_head:
> + cbdq->channel.data_head = round_up(cbdq->channel.data_head + cbd_req->data_len, PAGE_SIZE);
> + cbdq->channel.data_head %= cbdq->channel.data_size;
> +
> + return;
> +}
> +
> +static void complete_inflight_req(struct cbd_queue *cbdq, struct cbd_request *cbd_req, int ret);
> +static void cbd_queue_fn(struct cbd_request *cbd_req)
> +{
> + struct cbd_queue *cbdq = cbd_req->cbdq;
> + int ret = 0;
> + size_t command_size;
> +
> + spin_lock(&cbdq->inflight_reqs_lock);
> + list_add_tail(&cbd_req->inflight_reqs_node, &cbdq->inflight_reqs);
> + spin_unlock(&cbdq->inflight_reqs_lock);
> +
> + command_size = cbd_get_cmd_size(cbd_req);
> +
> + spin_lock(&cbdq->channel.cmdr_lock);
> + if (req_op(cbd_req->req) == REQ_OP_WRITE || req_op(cbd_req->req) == REQ_OP_READ) {
> + cbd_req->data_off = cbdq->channel.data_head;
> + cbd_req->data_len = blk_rq_bytes(cbd_req->req);
> + } else {
> + cbd_req->data_off = -1;
> + cbd_req->data_len = 0;
> + }
> +
> + if (!submit_ring_space_enough(cbdq, command_size) ||
> + !data_space_enough(cbdq, cbd_req)) {
> + spin_unlock(&cbdq->channel.cmdr_lock);
> +
> + /* remove request from inflight_reqs */
> + spin_lock(&cbdq->inflight_reqs_lock);
> + list_del_init(&cbd_req->inflight_reqs_node);
> + spin_unlock(&cbdq->inflight_reqs_lock);
> +
> + cbd_blk_debug(cbdq->cbd_blkdev, "transport space is not enough");
> + ret = -ENOMEM;
> + goto end_request;
> + }
> +
> + insert_padding(cbdq, command_size);
> +
> + cbd_req->req_tid = ++cbdq->req_tid;
> + queue_req_se_init(cbd_req);
> + cbdt_flush_range(cbdq->cbd_blkdev->cbdt, cbd_req->se, sizeof(struct cbd_se));
> +
> + if (!cbd_req_nodata(cbd_req)) {
> + queue_req_data_init(cbd_req);
> + }
> +
> + queue_delayed_work(cbdq->task_wq, &cbdq->complete_work, 0);
> +
> + CBDC_UPDATE_CMDR_HEAD(cbdq->channel_info->cmd_head,
> + cbd_get_cmd_size(cbd_req),
> + cbdq->channel_info->cmdr_size);
> + cbdc_flush_ctrl(&cbdq->channel);
> + spin_unlock(&cbdq->channel.cmdr_lock);
> +
> + return;
> +
> +end_request:
> + if (ret == -ENOMEM || ret == -EBUSY)
> + blk_mq_requeue_request(cbd_req->req, true);
> + else
> + blk_mq_end_request(cbd_req->req, errno_to_blk_status(ret));
> +
> + return;
> +}
> +
> +static void cbd_req_release(struct cbd_request *cbd_req)
> +{
> + return;
> +}
> +
> +static void advance_cmd_ring(struct cbd_queue *cbdq)
> +{
> + struct cbd_se *se;
> +again:
> + se = get_oldest_se(cbdq);
> + if (!se)
> + goto out;
> +
> + if (cbd_se_hdr_flags_test(se, CBD_SE_HDR_DONE)) {
> + CBDC_UPDATE_CMDR_TAIL(cbdq->channel_info->cmd_tail,
> + cbd_se_hdr_get_len(se->header.len_op),
> + cbdq->channel_info->cmdr_size);
> + cbdc_flush_ctrl(&cbdq->channel);
> + goto again;
> + }
> +out:
> + return;
> +}
> +
> +static bool __advance_data_tail(struct cbd_queue *cbdq, u32 data_off, u32 data_len)
> +{
> + if (data_off == cbdq->channel.data_tail) {
> + cbdq->released_extents[data_off / 4096] = 0;
> + cbdq->channel.data_tail += data_len;
> + if (cbdq->channel.data_tail >= cbdq->channel.data_size) {
> + cbdq->channel.data_tail %= cbdq->channel.data_size;
> + }
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static void advance_data_tail(struct cbd_queue *cbdq, u32 data_off, u32 data_len)
> +{
> + cbdq->released_extents[data_off / 4096] = data_len;
> +
> + while (__advance_data_tail(cbdq, data_off, data_len)) {
> + data_off += data_len;
> + data_len = cbdq->released_extents[data_off / 4096];
> + if (!data_len) {
> + break;
> + }
> + }
> +}
> +
> +static inline void complete_inflight_req(struct cbd_queue *cbdq, struct cbd_request *cbd_req, int ret)
> +{
> + u32 data_off, data_len;
> + bool advance_data = false;
> +
> + spin_lock(&cbdq->inflight_reqs_lock);
> + list_del_init(&cbd_req->inflight_reqs_node);
> + spin_unlock(&cbdq->inflight_reqs_lock);
> +
> + cbd_se_hdr_flags_set(cbd_req->se, CBD_SE_HDR_DONE);
> + data_off = cbd_req->data_off;
> + data_len = cbd_req->data_len;
> + advance_data = (!cbd_req_nodata(cbd_req));
> +
> + blk_mq_end_request(cbd_req->req, errno_to_blk_status(ret));
> +
> + cbd_req_release(cbd_req);
> +
> + spin_lock(&cbdq->channel.cmdr_lock);
> + advance_cmd_ring(cbdq);
> + if (advance_data)
> + advance_data_tail(cbdq, data_off, round_up(data_len, PAGE_SIZE));
> + spin_unlock(&cbdq->channel.cmdr_lock);
> +}
> +
> +static struct cbd_request *fetch_inflight_req(struct cbd_queue *cbdq, u64 req_tid)
> +{
> + struct cbd_request *req;
> + bool found = false;
> +
> + list_for_each_entry(req, &cbdq->inflight_reqs, inflight_reqs_node) {
> + if (req->req_tid == req_tid) {
> + list_del_init(&req->inflight_reqs_node);
> + found = true;
> + break;
> + }
> + }
> +
> + if (found)
> + return req;
> +
> + return NULL;
> +}
> +
> +static void copy_data_from_cbdteq(struct cbd_request *cbd_req)
> +{
> + struct bio *bio = cbd_req->req->bio;
> + struct cbd_queue *cbdq = cbd_req->cbdq;
> +
> + cbdc_copy_to_bio(&cbdq->channel, cbd_req->data_off, cbd_req->data_len, bio);
> +
> + return;
> +}
> +
> +static void complete_work_fn(struct work_struct *work)
> +{
> + struct cbd_queue *cbdq = container_of(work, struct cbd_queue, complete_work.work);
> + struct cbd_ce *ce;
> + struct cbd_request *cbd_req;
> +
> +again:
> + /* compr_head would be updated by backend handler */
> + cbdc_flush_ctrl(&cbdq->channel);
> +
> + spin_lock(&cbdq->channel.compr_lock);
> + ce = get_complete_entry(cbdq);
> + if (!ce) {
> + spin_unlock(&cbdq->channel.compr_lock);
> + if (cbdwc_need_retry(&cbdq->complete_worker_cfg)) {
> + goto again;
> + }
> +
> + spin_lock(&cbdq->inflight_reqs_lock);
> + if (list_empty(&cbdq->inflight_reqs)) {
> + spin_unlock(&cbdq->inflight_reqs_lock);
> + cbdwc_init(&cbdq->complete_worker_cfg);
> + return;
> + }
> + spin_unlock(&cbdq->inflight_reqs_lock);
> +
> + cbdwc_miss(&cbdq->complete_worker_cfg);
> +
> + queue_delayed_work(cbdq->task_wq, &cbdq->complete_work, 0);
> + return;
> + }
> + cbdwc_hit(&cbdq->complete_worker_cfg);
> + CBDC_UPDATE_COMPR_TAIL(cbdq->channel_info->compr_tail,
> + sizeof(struct cbd_ce),
> + cbdq->channel_info->compr_size);
> + cbdc_flush_ctrl(&cbdq->channel);
> + spin_unlock(&cbdq->channel.compr_lock);
> +
> + spin_lock(&cbdq->inflight_reqs_lock);
> + /* flush to ensure the content of ce is uptodate */
> + cbdt_flush_range(cbdq->cbd_blkdev->cbdt, ce, sizeof(*ce));
> + cbd_req = fetch_inflight_req(cbdq, ce->priv_data);
> + spin_unlock(&cbdq->inflight_reqs_lock);
> + if (!cbd_req) {
> + goto again;
> + }
> +
> + if (req_op(cbd_req->req) == REQ_OP_READ) {
> + spin_lock(&cbdq->channel.cmdr_lock);
> + copy_data_from_cbdteq(cbd_req);
> + spin_unlock(&cbdq->channel.cmdr_lock);
> + }
> +
> + complete_inflight_req(cbdq, cbd_req, ce->result);
> +
> + goto again;
> +}
> +
> +static blk_status_t cbd_queue_rq(struct blk_mq_hw_ctx *hctx,
> + const struct blk_mq_queue_data *bd)
> +{
> + struct request *req = bd->rq;
> + struct cbd_queue *cbdq = hctx->driver_data;
> + struct cbd_request *cbd_req = blk_mq_rq_to_pdu(bd->rq);
> +
> + memset(cbd_req, 0, sizeof(struct cbd_request));
> + INIT_LIST_HEAD(&cbd_req->inflight_reqs_node);
> +
> + blk_mq_start_request(bd->rq);
> +
> + switch (req_op(bd->rq)) {
> + case REQ_OP_FLUSH:
> + cbd_req_init(cbdq, CBD_OP_FLUSH, req);
> + break;
> + case REQ_OP_DISCARD:
> + cbd_req_init(cbdq, CBD_OP_DISCARD, req);
> + break;
> + case REQ_OP_WRITE_ZEROES:
> + cbd_req_init(cbdq, CBD_OP_WRITE_ZEROS, req);
> + break;
> + case REQ_OP_WRITE:
> + cbd_req_init(cbdq, CBD_OP_WRITE, req);
> + break;
> + case REQ_OP_READ:
> + cbd_req_init(cbdq, CBD_OP_READ, req);
> + break;
> + default:
> + return BLK_STS_IOERR;
> + }
> +
> + cbd_queue_fn(cbd_req);
> +
> + return BLK_STS_OK;
> +}
> +
> +static int cbd_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
> + unsigned int hctx_idx)
> +{
> + struct cbd_blkdev *cbd_blkdev = driver_data;
> + struct cbd_queue *cbdq;
> +
> + cbdq = &cbd_blkdev->queues[hctx_idx];
> + hctx->driver_data = cbdq;
> +
> + return 0;
> +}
> +
> +const struct blk_mq_ops cbd_mq_ops = {
> + .queue_rq = cbd_queue_rq,
> + .init_hctx = cbd_init_hctx,
> +};
> +
> +static int cbd_queue_channel_init(struct cbd_queue *cbdq, u32 channel_id)
> +{
> + struct cbd_blkdev *cbd_blkdev = cbdq->cbd_blkdev;
> + struct cbd_transport *cbdt = cbd_blkdev->cbdt;
> +
> + cbdq->channel_id = channel_id;
> + cbd_channel_init(&cbdq->channel, cbdt, channel_id);
> + cbdq->channel_info = cbdq->channel.channel_info;
> +
> + cbdq->channel.data_head = cbdq->channel.data_tail = 0;
> +
> + /* Initialise the channel_info of the ring buffer */
> + cbdq->channel_info->cmdr_off = CBDC_CMDR_OFF;
> + cbdq->channel_info->cmdr_size = CBDC_CMDR_SIZE;
> + cbdq->channel_info->compr_off = CBDC_COMPR_OFF;
> + cbdq->channel_info->compr_size = CBDC_COMPR_SIZE;
> +
> + cbdq->channel_info->backend_id = cbd_blkdev->backend_id;
> + cbdq->channel_info->blkdev_id = cbd_blkdev->blkdev_id;
> + cbdq->channel_info->blkdev_state = cbdc_blkdev_state_running;
> + cbdq->channel_info->state = cbd_channel_state_running;
> +
> + cbdc_flush_ctrl(&cbdq->channel);
> +
> + return 0;
> +}
> +
> +int cbd_queue_start(struct cbd_queue *cbdq)
> +{
> + struct cbd_transport *cbdt = cbdq->cbd_blkdev->cbdt;
> + u32 channel_id;
> + int ret;
> +
> + ret = cbdt_get_empty_channel_id(cbdt, &channel_id);
> + if (ret < 0) {
> + cbdt_err(cbdt, "failed find available channel_id.\n");
> + goto err;
> + }
> +
> + ret = cbd_queue_channel_init(cbdq, channel_id);
> + if (ret) {
> + cbd_queue_err(cbdq, "failed to init dev channel_info: %d.", ret);
> + goto err;
> + }
> +
> + INIT_LIST_HEAD(&cbdq->inflight_reqs);
> + spin_lock_init(&cbdq->inflight_reqs_lock);
> + cbdq->req_tid = 0;
> + INIT_DELAYED_WORK(&cbdq->complete_work, complete_work_fn);
> + cbdwc_init(&cbdq->complete_worker_cfg);
> +
> + cbdq->released_extents = kmalloc(sizeof(u32) * (CBDC_DATA_SIZE >> PAGE_SHIFT), GFP_KERNEL);
Quick fixup, this would be kzalloc, the fix path is available at branch
cbd of repo: https://github.com/DataTravelGuide/linux.git
cbd: fixup: initilize cbdq->released_extents with zeros
We have to initialize cbdq->released_extents with zeros, that means
there is no released extents. Otherwise, it will make advance_data_tail
confusing, and IO would be hang over.
Signed-off-by: Dongsheng Yang <dongsheng.yang.linux@...il.com>
diff --git a/drivers/block/cbd/cbd_queue.c b/drivers/block/cbd/cbd_queue.c
index 6709ac016e18..ebde191eb907 100644
--- a/drivers/block/cbd/cbd_queue.c
+++ b/drivers/block/cbd/cbd_queue.c
@@ -576,7 +576,7 @@ int cbd_queue_start(struct cbd_queue *cbdq)
INIT_DELAYED_WORK(&cbdq->complete_work, complete_work_fn);
cbdwc_init(&cbdq->complete_worker_cfg);
- cbdq->released_extents = kmalloc(sizeof(u32) * (CBDC_DATA_SIZE
>> PAGE_SHIFT), GFP_KERNEL);
+ cbdq->released_extents = kzalloc(sizeof(u32) * (CBDC_DATA_SIZE
>> PAGE_SHIFT), GFP_KERNEL);
if (!cbdq->released_extents) {
ret = -ENOMEM;
goto err;
> + if (!cbdq->released_extents) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + cbdq->task_wq = alloc_workqueue("cbd%d-queue%u", WQ_UNBOUND | WQ_MEM_RECLAIM,
> + 0, cbdq->cbd_blkdev->mapped_id, cbdq->index);
> + if (!cbdq->task_wq) {
> + ret = -ENOMEM;
> + goto released_extents_free;
> + }
> +
> + queue_delayed_work(cbdq->task_wq, &cbdq->complete_work, 0);
> +
> + atomic_set(&cbdq->state, cbd_queue_state_running);
> +
> + return 0;
> +
> +released_extents_free:
> + kfree(cbdq->released_extents);
> +err:
> + return ret;
> +}
> +
> +void cbd_queue_stop(struct cbd_queue *cbdq)
> +{
> + if (atomic_cmpxchg(&cbdq->state,
> + cbd_queue_state_running,
> + cbd_queue_state_none) != cbd_queue_state_running)
> + return;
> +
> + cancel_delayed_work_sync(&cbdq->complete_work);
> + drain_workqueue(cbdq->task_wq);
> + destroy_workqueue(cbdq->task_wq);
> +
> + kfree(cbdq->released_extents);
> + cbdq->channel_info->blkdev_state = cbdc_blkdev_state_none;
> +
> + cbdc_flush_ctrl(&cbdq->channel);
> +
> + return;
> +}
> diff --git a/drivers/block/cbd/cbd_transport.c b/drivers/block/cbd/cbd_transport.c
> index 4dd9bf1b5fd5..75b9d34218fc 100644
> --- a/drivers/block/cbd/cbd_transport.c
> +++ b/drivers/block/cbd/cbd_transport.c
> @@ -315,8 +315,19 @@ static ssize_t cbd_adm_store(struct device *dev,
> case CBDT_ADM_OP_B_CLEAR:
> break;
> case CBDT_ADM_OP_DEV_START:
> + if (opts.blkdev.queues > CBD_QUEUES_MAX) {
> + cbdt_err(cbdt, "invalid queues = %u, larger than max %u\n",
> + opts.blkdev.queues, CBD_QUEUES_MAX);
> + return -EINVAL;
> + }
> + ret = cbd_blkdev_start(cbdt, opts.backend_id, opts.blkdev.queues);
> + if (ret < 0)
> + return ret;
> break;
> case CBDT_ADM_OP_DEV_STOP:
> + ret = cbd_blkdev_stop(cbdt, opts.blkdev.devid);
> + if (ret < 0)
> + return ret;
> break;
> default:
> pr_err("invalid op: %d\n", opts.op);
>
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