Re: [f2fs-dev] [PATCH v2] f2fs: add async reset zone command support

[Chao Yu <chao@kernel.org>]

On 2023/4/25 16:10, Daejun Park wrote:
> Changelog:
> 
> v1 -> v2
> Changed to apply the optional async reset write pointer by default.
> 
> 
> This patch enables submit reset zone command asynchornously. It helps
> decrease average latency of write IOs in high utilization scenario by
> faster checkpointing.
> 
> Signed-off-by: Daejun Park <daejun7.park@samsung.com>
> ---
>   fs/f2fs/segment.c           | 95 ++++++++++++++++++++++++++++++++++---
>   include/trace/events/f2fs.h | 18 ++++++-
>   2 files changed, 105 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 82430f80c5da..27074a6eaf20 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1195,6 +1195,46 @@ static void __init_discard_policy(struct f2fs_sb_info *sbi,
>   static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
>   				struct block_device *bdev, block_t lstart,
>   				block_t start, block_t len);
> +
> +#ifdef CONFIG_BLK_DEV_ZONED
> +static int __submit_zone_reset_cmd(struct f2fs_sb_info *sbi,
> +				   struct discard_cmd *dc, blk_opf_t flag,
> +				   struct list_head *wait_list,
> +				   unsigned int *issued)
> +{
> +	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
> +	struct block_device *bdev = dc->bdev;
> +	struct bio *bio = bio_alloc(bdev, 0, REQ_OP_ZONE_RESET | flag, GFP_NOFS);
> +	unsigned long flags;
> +
> +	trace_f2fs_issue_reset_zone(bdev, SECTOR_FROM_BLOCK(dc->di.start));

trace_f2fs_issue_reset_zone(bdev, dc->di.start); ?

> +
> +	spin_lock_irqsave(&dc->lock, flags);
> +	dc->state = D_SUBMIT;
> +	dc->bio_ref++;
> +	spin_unlock_irqrestore(&dc->lock, flags);
> +
> +	if (issued)
> +		(*issued)++;
> +
> +	atomic_inc(&dcc->queued_discard);
> +	dc->queued++;
> +	list_move_tail(&dc->list, wait_list);
> +
> +	/* sanity check on discard range */
> +	__check_sit_bitmap(sbi, dc->di.lstart, dc->di.lstart + dc->di.len);
> +
> +	bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(dc->di.start);
> +	bio->bi_private = dc;
> +	bio->bi_end_io = f2fs_submit_discard_endio;
> +	submit_bio(bio);
> +
> +	atomic_inc(&dcc->issued_discard);
> +
> +	return 0;

Unneeded return value?

> +}
> +#endif
> +
>   /* this function is copied from blkdev_issue_discard from block/blk-lib.c */
>   static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
>   				struct discard_policy *dpolicy,
> @@ -1216,6 +1256,11 @@ static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
>   	if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
>   		return 0;
>   
> +#ifdef CONFIG_BLK_DEV_ZONED
> +	if (f2fs_sb_has_blkzoned(sbi) && bdev_is_zoned(bdev))
> +		return __submit_zone_reset_cmd(sbi, dc, flag, wait_list, issued);
> +#endif
> +
>   	trace_f2fs_issue_discard(bdev, dc->di.start, dc->di.len);
>   
>   	lstart = dc->di.lstart;
> @@ -1460,21 +1505,42 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
>   	}
>   }
>   
> +#ifdef CONFIG_BLK_DEV_ZONED
> +static void __queue_zone_reset_cmd(struct f2fs_sb_info *sbi,
> +		struct block_device *bdev, block_t blkstart, block_t blklen)

block_t lblkstart,

> +{
> +	block_t lblkstart = blkstart;

block_t blkstart = lblkstart;

> +
> +	if (f2fs_is_multi_device(sbi)) {
> +		int devi = f2fs_target_device_index(sbi, blkstart);
> +
> +		blkstart -= FDEV(devi).start_blk;
> +	}
> +
> +	trace_f2fs_queue_reset_zone(bdev, blkstart);
> +
> +	mutex_lock(&SM_I(sbi)->dcc_info->cmd_lock);
> +	__insert_discard_cmd(sbi, bdev, lblkstart, blkstart, blklen);
> +	mutex_unlock(&SM_I(sbi)->dcc_info->cmd_lock);
> +}
> +#endif
> +
>   static void __queue_discard_cmd(struct f2fs_sb_info *sbi,
>   		struct block_device *bdev, block_t blkstart, block_t blklen)
>   {
>   	block_t lblkstart = blkstart;
>   
> +	trace_f2fs_queue_discard(bdev, blkstart, blklen);

If device doesn't support discard, it's better not show above tracepoint?

> +
>   	if (!f2fs_bdev_support_discard(bdev))
>   		return;
>   
> -	trace_f2fs_queue_discard(bdev, blkstart, blklen);
> -
>   	if (f2fs_is_multi_device(sbi)) {
>   		int devi = f2fs_target_device_index(sbi, blkstart);
>   
>   		blkstart -= FDEV(devi).start_blk;
>   	}
> +
>   	mutex_lock(&SM_I(sbi)->dcc_info->cmd_lock);
>   	__update_discard_tree_range(sbi, bdev, lblkstart, blkstart, blklen);
>   	mutex_unlock(&SM_I(sbi)->dcc_info->cmd_lock);
> @@ -1725,7 +1791,18 @@ static void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
>   	dc = __lookup_discard_cmd(sbi, blkaddr);
>   	if (dc) {
>   		if (dc->state == D_PREP) {
> -			__punch_discard_cmd(sbi, dc, blkaddr);
> +			if (f2fs_sb_has_blkzoned(sbi) &&
> +			    bdev_is_zoned(dc->bdev)) {
> +				struct discard_policy dpolicy;
> +				/* force submit zone reset */
> +				__init_discard_policy(sbi, &dpolicy,
> +						      DPOLICY_FORCE, 1);
> +				__submit_discard_cmd(sbi, &dpolicy, dc, NULL);

Can we call __submit_zone_reset_cmd() directly?

Thanks,

> +				dc->ref++;
> +				need_wait = true;
> +			} else {
> +				__punch_discard_cmd(sbi, dc, blkaddr);
> +			}
>   		} else {
>   			dc->ref++;
>   			need_wait = true;
> @@ -1875,9 +1952,15 @@ static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
>   				 blkstart, blklen);
>   			return -EIO;
>   		}
> -		trace_f2fs_issue_reset_zone(bdev, blkstart);
> -		return blkdev_zone_mgmt(bdev, REQ_OP_ZONE_RESET,
> -					sector, nr_sects, GFP_NOFS);
> +
> +		if (unlikely(!is_sbi_flag_set(sbi, SBI_POR_DOING))) {
> +			trace_f2fs_issue_reset_zone(bdev, blkstart);
> +			return blkdev_zone_mgmt(bdev, REQ_OP_ZONE_RESET,
> +						sector, nr_sects, GFP_NOFS);
> +		}
> +
> +		__queue_zone_reset_cmd(sbi, bdev, lblkstart, blklen);
> +		return 0;
>   	}
>   
>   	/* For conventional zones, use regular discard if supported */
> diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
> index 99cbc5949e3c..ee1477de8324 100644
> --- a/include/trace/events/f2fs.h
> +++ b/include/trace/events/f2fs.h
> @@ -1512,7 +1512,7 @@ DEFINE_EVENT(f2fs_discard, f2fs_remove_discard,
>   	TP_ARGS(dev, blkstart, blklen)
>   );
>   
> -TRACE_EVENT(f2fs_issue_reset_zone,
> +DECLARE_EVENT_CLASS(f2fs_reset_zone,
>   
>   	TP_PROTO(struct block_device *dev, block_t blkstart),
>   
> @@ -1528,11 +1528,25 @@ TRACE_EVENT(f2fs_issue_reset_zone,
>   		__entry->blkstart = blkstart;
>   	),
>   
> -	TP_printk("dev = (%d,%d), reset zone at block = 0x%llx",
> +	TP_printk("dev = (%d,%d), zone at block = 0x%llx",
>   		show_dev(__entry->dev),
>   		(unsigned long long)__entry->blkstart)
>   );
>   
> +DEFINE_EVENT(f2fs_reset_zone, f2fs_queue_reset_zone,
> +
> +	TP_PROTO(struct block_device *dev, block_t blkstart),
> +
> +	TP_ARGS(dev, blkstart)
> +);
> +
> +DEFINE_EVENT(f2fs_reset_zone, f2fs_issue_reset_zone,
> +
> +	TP_PROTO(struct block_device *dev, block_t blkstart),
> +
> +	TP_ARGS(dev, blkstart)
> +);
> +
>   TRACE_EVENT(f2fs_issue_flush,
>   
>   	TP_PROTO(struct block_device *dev, unsigned int nobarrier,


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