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Date:   Tue, 9 May 2023 11:53:35 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Daejun Park <daejun7.park@samsung.com>
Cc:     "chao@kernel.org" <chao@kernel.org>,
        "rostedt@goodmis.org" <rostedt@goodmis.org>,
        "mhiramat@kernel.org" <mhiramat@kernel.org>,
        "linux-f2fs-devel@lists.sourceforge.net" 
        <linux-f2fs-devel@lists.sourceforge.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-trace-kernel@vger.kernel.org" 
        <linux-trace-kernel@vger.kernel.org>,
        Seokhwan Kim <sukka.kim@samsung.com>,
        Yonggil Song <yonggil.song@samsung.com>,
        beomsu kim <beomsu7.kim@samsung.com>
Subject: Re: [PATCH v6] f2fs: add async reset zone command support
Message-ID: <ZFqWr3sSYMsHtHAC@google.com>
References: <CGME20230508081042epcms2p8a637deae7de1829f54614e09d5fde5e5@epcms2p8>
 <20230508081042epcms2p8a637deae7de1829f54614e09d5fde5e5@epcms2p8>
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On 05/08, Daejun Park wrote:
> v5 -> v6
> Added trace_f2fs_iostat support for zone reset command.
> 
> v4 -> v5
> Added f2fs iostat for zone reset command.
> 
> v3 -> v4
> Fixed build error caused by unused function.
> 
> v2 -> v3
> Modified arguments to be correct for ftrace parameter.
> Changed __submit_zone_reset_cmd to void return.
> Refactored the f2fs_wait_discard_bio function.
> Fixed code that was previously incorrectly merged.
> 
> v1 -> v2
> Changed to apply the optional async reset write pointer by default.

Don't add the history in the patch description.

> 
> 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/f2fs.h              |  1 +
>  fs/f2fs/iostat.c            |  1 +
>  fs/f2fs/segment.c           | 84 +++++++++++++++++++++++++++++++++++--
>  include/trace/events/f2fs.h | 24 +++++++++--
>  4 files changed, 104 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index d211ee89c158..51b68a629814 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1175,6 +1175,7 @@ enum iostat_type {
>  	/* other */
>  	FS_DISCARD_IO,			/* discard */
>  	FS_FLUSH_IO,			/* flush */
> +	FS_ZONE_RESET_IO,		/* zone reset */
>  	NR_IO_TYPE,
>  };
>  
> diff --git a/fs/f2fs/iostat.c b/fs/f2fs/iostat.c
> index 3d5bfb1ad585..f8703038e1d8 100644
> --- a/fs/f2fs/iostat.c
> +++ b/fs/f2fs/iostat.c
> @@ -80,6 +80,7 @@ int __maybe_unused iostat_info_seq_show(struct seq_file *seq, void *offset)
>  	seq_puts(seq, "[OTHER]\n");
>  	IOSTAT_INFO_SHOW("fs discard", FS_DISCARD_IO);
>  	IOSTAT_INFO_SHOW("fs flush", FS_FLUSH_IO);
> +	IOSTAT_INFO_SHOW("fs zone reset", FS_ZONE_RESET_IO);
>  
>  	return 0;
>  }
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 6db410f1bb8c..4802b05a795b 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1196,6 +1196,45 @@ 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 void __submit_zone_reset_cmd(struct f2fs_sb_info *sbi,

Why can't we use __f2fs_issue_discard_zone()?

> +				   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, 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);
> +	f2fs_update_iostat(sbi, NULL, FS_ZONE_RESET_IO, dc->di.len * F2FS_BLKSIZE);
> +}
> +#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,
> @@ -1217,6 +1256,13 @@ 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)) {
> +		__submit_zone_reset_cmd(sbi, dc, flag, wait_list, issued);
> +		return 0;
> +	}
> +#endif
> +
>  	trace_f2fs_issue_discard(bdev, dc->di.start, dc->di.len);
>  
>  	lstart = dc->di.lstart;
> @@ -1461,6 +1507,19 @@ 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 lblkstart,
> +		block_t blklen)
> +{
> +	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)
>  {
> @@ -1724,6 +1783,19 @@ static void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
>  
>  	mutex_lock(&dcc->cmd_lock);
>  	dc = __lookup_discard_cmd(sbi, blkaddr);
> +#ifdef CONFIG_BLK_DEV_ZONED
> +	if (dc && f2fs_sb_has_blkzoned(sbi) && bdev_is_zoned(dc->bdev)) {
> +		/* force submit zone reset */
> +		if (dc->state == D_PREP)
> +			__submit_zone_reset_cmd(sbi, dc, REQ_SYNC,
> +						&dcc->wait_list, NULL);
> +		dc->ref++;
> +		mutex_unlock(&dcc->cmd_lock);
> +		/* wait zone reset */
> +		__wait_one_discard_bio(sbi, dc);
> +		return;
> +	}
> +#endif
>  	if (dc) {
>  		if (dc->state == D_PREP) {
>  			__punch_discard_cmd(sbi, dc, blkaddr);
> @@ -1876,9 +1948,15 @@ 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, blkstart, 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..793f82cc1515 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,
> @@ -1979,6 +1993,7 @@ TRACE_EVENT(f2fs_iostat,
>  		__field(unsigned long long,	fs_nrio)
>  		__field(unsigned long long,	fs_mrio)
>  		__field(unsigned long long,	fs_discard)
> +		__field(unsigned long long,	fs_reset_zone)
>  	),
>  
>  	TP_fast_assign(
> @@ -2010,12 +2025,14 @@ TRACE_EVENT(f2fs_iostat,
>  		__entry->fs_nrio	= iostat[FS_NODE_READ_IO];
>  		__entry->fs_mrio	= iostat[FS_META_READ_IO];
>  		__entry->fs_discard	= iostat[FS_DISCARD_IO];
> +		__entry->fs_reset_zone	= iostat[FS_ZONE_RESET_IO];
>  	),
>  
>  	TP_printk("dev = (%d,%d), "
>  		"app [write=%llu (direct=%llu, buffered=%llu), mapped=%llu, "
>  		"compr(buffered=%llu, mapped=%llu)], "
> -		"fs [data=%llu, cdata=%llu, node=%llu, meta=%llu, discard=%llu], "
> +		"fs [data=%llu, cdata=%llu, node=%llu, meta=%llu, discard=%llu, "
> +		"reset_zone=%llu], "
>  		"gc [data=%llu, node=%llu], "
>  		"cp [data=%llu, node=%llu, meta=%llu], "
>  		"app [read=%llu (direct=%llu, buffered=%llu), mapped=%llu], "
> @@ -2026,6 +2043,7 @@ TRACE_EVENT(f2fs_iostat,
>  		__entry->app_bio, __entry->app_mio, __entry->app_bcdio,
>  		__entry->app_mcdio, __entry->fs_dio, __entry->fs_cdio,
>  		__entry->fs_nio, __entry->fs_mio, __entry->fs_discard,
> +		__entry->fs_reset_zone,
>  		__entry->fs_gc_dio, __entry->fs_gc_nio, __entry->fs_cp_dio,
>  		__entry->fs_cp_nio, __entry->fs_cp_mio,
>  		__entry->app_rio, __entry->app_drio, __entry->app_brio,
> -- 
> 2.25.1