On 2021/05/19 18:36, Christoph Hellwig wrote:
> The logic looks fine to me, but this makes blkdev_zone_mgmt extremely
> convoluted. What do you think of the version below that splits out
> two self contained helpers instead?
Yep, that works for me. Will use this in v2.
>
> ---
> From 3ff31f2502cf032ac1331122c9f1a018b769b577 Mon Sep 17 00:00:00 2001
> From: Damien Le Moal <damien.lemoal@xxxxxxx>
> Date: Wed, 19 May 2021 11:55:19 +0900
> Subject: block: improve handling of all zones reset operation
>
> SCSI, ZNS and null_blk zoned devices support resetting all zones using
> a single command (REQ_OP_ZONE_RESET_ALL), as indicated using the device
> request queue flag QUEUE_FLAG_ZONE_RESETALL. This flag is not set for
> device mapper targets creating zoned devices. In this case, a user
> request for resetting all zones of a device is processed in
> blkdev_zone_mgmt() by issuing a REQ_OP_ZONE_RESET operation for each
> zone of the device. This leads to different behaviors of the
> BLKRESETZONE ioctl() depending on the target device support for the
> reset all operation. E.g.
>
> blkzone reset /dev/sdX
>
> will reset all zones of a SCSI device using a single command that will
> ignore conventional, read-only or offline zones.
>
> But a dm-linear device including conventional, read-only or offline
> zones cannot be reset in the same manner as some of the single zone
> reset operations issued by blkdev_zone_mgmt() will fail. E.g.:
>
> blkzone reset /dev/dm-Y
> blkzone: /dev/dm-0: BLKRESETZONE ioctl failed: Remote I/O error
>
> To simplify applications and tools development, unify the behavior of
> an all-zone reset operation by modifying blkdev_zone_mgmt() to not
> issue a zone reset operation for conventional, read-only and offline
> zones, thus mimicking what an actual reset-all device command does on a
> device supporting REQ_OP_ZONE_RESET_ALL. The zones needing a reset are
> identified using a bitmap that is initialized using a zone report.
> Since empty zones do not need a reset, also ignore these zones.
>
> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>
> [hch: split into multiple functions]
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> block/blk-zoned.c | 115 +++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 88 insertions(+), 27 deletions(-)
>
> diff --git a/block/blk-zoned.c b/block/blk-zoned.c
> index 250cb76ee615..48e8376c1db8 100644
> --- a/block/blk-zoned.c
> +++ b/block/blk-zoned.c
> @@ -161,18 +161,85 @@ int blkdev_report_zones(struct block_device *bdev, sector_t sector,
> }
> EXPORT_SYMBOL_GPL(blkdev_report_zones);
>
> -static inline bool blkdev_allow_reset_all_zones(struct block_device *bdev,
> - sector_t sector,
> - sector_t nr_sectors)
> +static inline unsigned long *blk_alloc_zone_bitmap(int node,
> + unsigned int nr_zones)
> {
> - if (!blk_queue_zone_resetall(bdev_get_queue(bdev)))
> - return false;
> + return kcalloc_node(BITS_TO_LONGS(nr_zones), sizeof(unsigned long),
> + GFP_NOIO, node);
> +}
>
> +static int blk_zone_need_reset_cb(struct blk_zone *zone, unsigned int idx,
> + void *data)
> +{
> /*
> - * REQ_OP_ZONE_RESET_ALL can be executed only if the number of sectors
> - * of the applicable zone range is the entire disk.
> + * For an all-zones reset, ignore conventional, empty, read-only
> + * and offline zones.
> */
> - return !sector && nr_sectors == get_capacity(bdev->bd_disk);
> + switch (zone->cond) {
> + case BLK_ZONE_COND_NOT_WP:
> + case BLK_ZONE_COND_EMPTY:
> + case BLK_ZONE_COND_READONLY:
> + case BLK_ZONE_COND_OFFLINE:
> + return 0;
> + default:
> + set_bit(idx, (unsigned long *)data);
> + return 0;
> + }
> +}
> +
> +static int blkdev_zone_reset_all_emulated(struct block_device *bdev,
> + gfp_t gfp_mask)
> +{
> + struct request_queue *q = bdev_get_queue(bdev);
> + sector_t capacity = get_capacity(bdev->bd_disk);
> + sector_t zone_sectors = blk_queue_zone_sectors(q);
> + unsigned long *need_reset;
> + sector_t sector;
> + struct bio *bio = NULL;
> + int ret;
> +
> + need_reset = blk_alloc_zone_bitmap(q->node, q->nr_zones);
> + if (!need_reset)
> + return -ENOMEM;
> + ret = bdev->bd_disk->fops->report_zones(bdev->bd_disk, 0,
> + q->nr_zones, blk_zone_need_reset_cb,
> + need_reset);
> + if (ret < 0)
> + goto out_free_need_reset;
> +
> + ret = 0;
> + while (sector < capacity) {
> + if (!test_bit(blk_queue_zone_no(q, sector), need_reset)) {
> + sector += zone_sectors;
> + continue;
> + }
> + bio = blk_next_bio(bio, 0, gfp_mask);
> + bio_set_dev(bio, bdev);
> + bio->bi_opf = REQ_OP_ZONE_RESET | REQ_SYNC;
> + bio->bi_iter.bi_sector = sector;
> + sector += zone_sectors;
> +
> + /* This may take a while, so be nice to others */
> + cond_resched();
> + }
> +
> + if (bio) {
> + ret = submit_bio_wait(bio);
> + bio_put(bio);
> + }
> +out_free_need_reset:
> + kfree(need_reset);
> + return ret;
> +}
> +
> +static int blkdev_zone_reset_all(struct block_device *bdev, gfp_t gfp_mask)
> +{
> + struct bio bio;
> +
> + bio_init(&bio, NULL, 0);
> + bio_set_dev(&bio, bdev);
> + bio.bi_opf = REQ_OP_ZONE_RESET_ALL | REQ_SYNC;
> + return submit_bio_wait(&bio);
> }
>
> /**
> @@ -200,7 +267,7 @@ int blkdev_zone_mgmt(struct block_device *bdev, enum req_opf op,
> sector_t capacity = get_capacity(bdev->bd_disk);
> sector_t end_sector = sector + nr_sectors;
> struct bio *bio = NULL;
> - int ret;
> + int ret = 0;
>
> if (!blk_queue_is_zoned(q))
> return -EOPNOTSUPP;
> @@ -222,20 +289,21 @@ int blkdev_zone_mgmt(struct block_device *bdev, enum req_opf op,
> if ((nr_sectors & (zone_sectors - 1)) && end_sector != capacity)
> return -EINVAL;
>
> + /*
> + * In the case of a zone reset operation over all zones,
> + * REQ_OP_ZONE_RESET_ALL can be used with devices supporting this
> + * command. For other devices, we emulate this command behavior by
> + * identifying the zones needing a reset.
> + */
> + if (op == REQ_OP_ZONE_RESET && sector == 0 && nr_sectors == capacity) {
> + if (!blk_queue_zone_resetall(q))
> + return blkdev_zone_reset_all_emulated(bdev, gfp_mask);
> + return blkdev_zone_reset_all(bdev, gfp_mask);
> + }
> +
> while (sector < end_sector) {
> bio = blk_next_bio(bio, 0, gfp_mask);
> bio_set_dev(bio, bdev);
> -
> - /*
> - * Special case for the zone reset operation that reset all
> - * zones, this is useful for applications like mkfs.
> - */
> - if (op == REQ_OP_ZONE_RESET &&
> - blkdev_allow_reset_all_zones(bdev, sector, nr_sectors)) {
> - bio->bi_opf = REQ_OP_ZONE_RESET_ALL | REQ_SYNC;
> - break;
> - }
> -
> bio->bi_opf = op | REQ_SYNC;
> bio->bi_iter.bi_sector = sector;
> sector += zone_sectors;
> @@ -396,13 +464,6 @@ int blkdev_zone_mgmt_ioctl(struct block_device *bdev, fmode_t mode,
> return ret;
> }
>
> -static inline unsigned long *blk_alloc_zone_bitmap(int node,
> - unsigned int nr_zones)
> -{
> - return kcalloc_node(BITS_TO_LONGS(nr_zones), sizeof(unsigned long),
> - GFP_NOIO, node);
> -}
> -
> void blk_queue_free_zone_bitmaps(struct request_queue *q)
> {
> kfree(q->conv_zones_bitmap);
>
--
Damien Le Moal
Western Digital Research
