On Thu, 5 Dec 2019, Coly Li wrote:
> This is a very basic zoned device support. With this patch, bcache
> device is able to,
> - Export zoned device attribution via sysfs
> - Response report zones request, e.g. by command 'blkzone report'
> But the bcache device is still NOT able to,
> - Response any zoned device management request or IOCTL command
>
> Here are the testings I have done,
> - read /sys/block/bcache0/queue/zoned, content is 'host-managed'
> - read /sys/block/bcache0/queue/nr_zones, content is number of zones
> including all zone types.
> - read /sys/block/bcache0/queue/chunk_sectors, content is zone size
> in sectors.
> - run 'blkzone report /dev/bcache0', all zones information displayed.
> - run 'blkzone reset /dev/bcache0', operation is rejected with error
> information: "blkzone: /dev/bcache0: BLKRESETZONE ioctl failed:
> Operation not supported"
> - Sequential writes by dd, I can see some zones' write pointer 'wptr'
> values updated.
>
> All of these are very basic testings, if you have better testing
> tools or cases, please offer me hint.
Interesting.
1. should_writeback() could benefit by hinting true when an IO would fall
in a zoned region.
2. The writeback thread could writeback such that they prefer
fully(mostly)-populated zones when choosing what to write out.
--
Eric Wheeler
> Thanks in advance for your review and comments.
>
> Signed-off-by: Coly Li <colyli@xxxxxxx>
> CC: Damien Le Moal <damien.lemoal@xxxxxxx>
> CC: Hannes Reinecke <hare@xxxxxxxx>
> ---
> drivers/md/bcache/bcache.h | 10 ++++++
> drivers/md/bcache/request.c | 74 +++++++++++++++++++++++++++++++++++++++++++++
> drivers/md/bcache/super.c | 41 +++++++++++++++++++++++--
> 3 files changed, 122 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> index 9198c1b480d9..77c2040c99ee 100644
> --- a/drivers/md/bcache/bcache.h
> +++ b/drivers/md/bcache/bcache.h
> @@ -221,6 +221,7 @@ BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1);
> struct search;
> struct btree;
> struct keybuf;
> +struct bch_report_zones_args;
>
> struct keybuf_key {
> struct rb_node node;
> @@ -277,6 +278,8 @@ struct bcache_device {
> struct bio *bio, unsigned int sectors);
> int (*ioctl)(struct bcache_device *d, fmode_t mode,
> unsigned int cmd, unsigned long arg);
> + int (*report_zones)(struct bch_report_zones_args *args,
> + unsigned int nr_zones);
> };
>
> struct io {
> @@ -743,6 +746,13 @@ struct bbio {
> struct bio bio;
> };
>
> +struct bch_report_zones_args {
> + struct bcache_device *bcache_device;
> + sector_t sector;
> + void *orig_data;
> + report_zones_cb orig_cb;
> +};
> +
> #define BTREE_PRIO USHRT_MAX
> #define INITIAL_PRIO 32768U
>
> diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
> index 7555e4a93145..d82425300383 100644
> --- a/drivers/md/bcache/request.c
> +++ b/drivers/md/bcache/request.c
> @@ -1162,6 +1162,19 @@ static blk_qc_t cached_dev_make_request(struct request_queue *q,
> }
> }
>
> + /*
> + * zone management request may change the data layout and content
> + * implicitly on backing device, which introduces unacceptible
> + * inconsistency between the backing device and the cache device.
> + * Therefore all zone management related request will be denied here.
> + */
> + if (op_is_zone_mgmt(bio->bi_opf)) {
> + pr_err_ratelimited("zoned device management request denied.");
> + bio->bi_status = BLK_STS_NOTSUPP;
> + bio_endio(bio);
> + return BLK_QC_T_NONE;
> + }
> +
> generic_start_io_acct(q,
> bio_op(bio),
> bio_sectors(bio),
> @@ -1205,6 +1218,24 @@ static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
> if (dc->io_disable)
> return -EIO;
>
> + /*
> + * zone management ioctl commands may change the data layout
> + * and content implicitly on backing device, which introduces
> + * unacceptible inconsistency between the backing device and
> + * the cache device. Therefore all zone management related
> + * ioctl commands will be denied here.
> + */
> + switch (cmd) {
> + case BLKRESETZONE:
> + case BLKOPENZONE:
> + case BLKCLOSEZONE:
> + case BLKFINISHZONE:
> + return -EOPNOTSUPP;
> + default:
> + /* Other commands fall through*/
> + break;
> + }
> +
> return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg);
> }
>
> @@ -1233,6 +1264,48 @@ static int cached_dev_congested(void *data, int bits)
> return ret;
> }
>
> +static int cached_dev_report_zones_cb(struct blk_zone *zone,
> + unsigned int idx,
> + void *data)
> +{
> + struct bch_report_zones_args *args = data;
> + struct bcache_device *d = args->bcache_device;
> + struct cached_dev *dc = container_of(d, struct cached_dev, disk);
> + unsigned long data_offset = dc->sb.data_offset;
> +
> + if (zone->start >= data_offset) {
> + zone->start -= data_offset;
> + zone->wp -= data_offset;
> + } else {
> + /*
> + * Normally the first zone is conventional zone,
> + * we don't need to worry about how to maintain
> + * the write pointer.
> + * But the zone->len is special, because the
> + * sector 0 on bcache device is 8KB offset on
> + * backing device indeed.
> + */
> + zone->len -= data_offset;
> + }
> +
> + return args->orig_cb(zone, idx, args->orig_data);
> +}
> +
> +static int cached_dev_report_zones(struct bch_report_zones_args *args,
> + unsigned int nr_zones)
> +{
> + struct bcache_device *d = args->bcache_device;
> + struct cached_dev *dc = container_of(d, struct cached_dev, disk);
> + sector_t sector = args->sector + dc->sb.data_offset;
> +
> + /* sector is real LBA of backing device */
> + return blkdev_report_zones(dc->bdev,
> + sector,
> + nr_zones,
> + cached_dev_report_zones_cb,
> + args);
> +}
> +
> void bch_cached_dev_request_init(struct cached_dev *dc)
> {
> struct gendisk *g = dc->disk.disk;
> @@ -1241,6 +1314,7 @@ void bch_cached_dev_request_init(struct cached_dev *dc)
> g->queue->backing_dev_info->congested_fn = cached_dev_congested;
> dc->disk.cache_miss = cached_dev_cache_miss;
> dc->disk.ioctl = cached_dev_ioctl;
> + dc->disk.report_zones = cached_dev_report_zones;
> }
>
> /* Flash backed devices */
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 77e9869345e7..7222fcafaf50 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -672,10 +672,32 @@ static int ioctl_dev(struct block_device *b, fmode_t mode,
> return d->ioctl(d, mode, cmd, arg);
> }
>
> +
> +static int report_zones_dev(struct gendisk *disk,
> + sector_t sector,
> + unsigned int nr_zones,
> + report_zones_cb cb,
> + void *data)
> +{
> + struct bcache_device *d = disk->private_data;
> + struct bch_report_zones_args args = {
> + .bcache_device = d,
> + .sector = sector,
> + .orig_data = data,
> + .orig_cb = cb,
> + };
> +
> + if (d->report_zones)
> + return d->report_zones(&args, nr_zones);
> +
> + return -EOPNOTSUPP;
> +}
> +
> static const struct block_device_operations bcache_ops = {
> .open = open_dev,
> .release = release_dev,
> .ioctl = ioctl_dev,
> + .report_zones = report_zones_dev,
> .owner = THIS_MODULE,
> };
>
> @@ -808,7 +830,9 @@ static void bcache_device_free(struct bcache_device *d)
> closure_debug_destroy(&d->cl);
> }
>
> -static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
> +static int bcache_device_init(struct cached_dev *dc,
> + struct bcache_device *d,
> + unsigned int block_size,
> sector_t sectors)
> {
> struct request_queue *q;
> @@ -882,6 +906,17 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
>
> blk_queue_write_cache(q, true, true);
>
> + /*
> + * If this is for backing device registration, and it is an
> + * zoned device (e.g. host-managed S.M.R. hard drive), set
> + * up zoned device attribution properly for sysfs interface.
> + */
> + if (dc && bdev_is_zoned(dc->bdev)) {
> + q->limits.zoned = bdev_zoned_model(dc->bdev);
> + q->nr_zones = blkdev_nr_zones(dc->bdev);
> + q->limits.chunk_sectors = bdev_zone_sectors(dc->bdev);
> + }
> +
> return 0;
>
> err:
> @@ -1328,7 +1363,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
> dc->partial_stripes_expensive =
> q->limits.raid_partial_stripes_expensive;
>
> - ret = bcache_device_init(&dc->disk, block_size,
> + ret = bcache_device_init(dc, &dc->disk, block_size,
> dc->bdev->bd_part->nr_sects - dc->sb.data_offset);
> if (ret)
> return ret;
> @@ -1445,7 +1480,7 @@ static int flash_dev_run(struct cache_set *c, struct uuid_entry *u)
>
> kobject_init(&d->kobj, &bch_flash_dev_ktype);
>
> - if (bcache_device_init(d, block_bytes(c), u->sectors))
> + if (bcache_device_init(NULL, d, block_bytes(c), u->sectors))
> goto err;
>
> bcache_device_attach(d, c, u - c->uuids);
> --
> 2.16.4
>
>
