Re: [PATCH 10/10] xfs: add sysfs stats for zoned GC

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Jan 27, 2026 at 05:05:50PM +0100, Christoph Hellwig wrote:
> Add counters of read, write and zone_reset operations as well as
> GC written bytes to sysfs.  This way they can be easily used for
> monitoring tools and test cases.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

+1 for observability
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_stats.c   | 7 ++++++-
>  fs/xfs/xfs_stats.h   | 6 ++++++
>  fs/xfs/xfs_zone_gc.c | 7 +++++++
>  3 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_stats.c b/fs/xfs/xfs_stats.c
> index 9781222e0653..6d7f98afa31a 100644
> --- a/fs/xfs/xfs_stats.c
> +++ b/fs/xfs/xfs_stats.c
> @@ -24,6 +24,7 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
>  	uint64_t	xs_write_bytes = 0;
>  	uint64_t	xs_read_bytes = 0;
>  	uint64_t	defer_relog = 0;
> +	uint64_t	xs_gc_write_bytes = 0;
>  
>  	static const struct xstats_entry {
>  		char	*desc;
> @@ -57,7 +58,8 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
>  		{ "rtrmapbt_mem",	xfsstats_offset(xs_rtrefcbt_2)	},
>  		{ "rtrefcntbt",		xfsstats_offset(xs_qm_dqreclaims)},
>  		/* we print both series of quota information together */
> -		{ "qm",			xfsstats_offset(xs_xstrat_bytes)},
> +		{ "qm",			xfsstats_offset(xs_gc_read_calls)},
> +		{ "zoned",		xfsstats_offset(__pad1)},
>  	};
>  
>  	/* Loop over all stats groups */
> @@ -77,6 +79,7 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
>  		xs_write_bytes += per_cpu_ptr(stats, i)->s.xs_write_bytes;
>  		xs_read_bytes += per_cpu_ptr(stats, i)->s.xs_read_bytes;
>  		defer_relog += per_cpu_ptr(stats, i)->s.defer_relog;
> +		xs_gc_write_bytes += per_cpu_ptr(stats, i)->s.xs_read_bytes;
>  	}
>  
>  	len += scnprintf(buf + len, PATH_MAX-len, "xpc %llu %llu %llu\n",
> @@ -89,6 +92,8 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
>  #else
>  		0);
>  #endif
> +	len += scnprintf(buf + len, PATH_MAX-len, "gc xpc %llu\n",
> +			xs_gc_write_bytes);
>  
>  	return len;
>  }
> diff --git a/fs/xfs/xfs_stats.h b/fs/xfs/xfs_stats.h
> index 15ba1abcf253..16dbbc0b72db 100644
> --- a/fs/xfs/xfs_stats.h
> +++ b/fs/xfs/xfs_stats.h
> @@ -138,10 +138,16 @@ struct __xfsstats {
>  	uint32_t		xs_qm_dqwants;
>  	uint32_t		xs_qm_dquot;
>  	uint32_t		xs_qm_dquot_unused;
> +/* Zone GC counters */
> +	uint32_t		xs_gc_read_calls;
> +	uint32_t		xs_gc_write_calls;
> +	uint32_t		xs_gc_zone_reset_calls;
> +	uint32_t		__pad1;
>  /* Extra precision counters */
>  	uint64_t		xs_xstrat_bytes;
>  	uint64_t		xs_write_bytes;
>  	uint64_t		xs_read_bytes;
> +	uint64_t		xs_gc_write_bytes;
>  	uint64_t		defer_relog;
>  };
>  
> diff --git a/fs/xfs/xfs_zone_gc.c b/fs/xfs/xfs_zone_gc.c
> index 570102184904..4bb647d3be41 100644
> --- a/fs/xfs/xfs_zone_gc.c
> +++ b/fs/xfs/xfs_zone_gc.c
> @@ -712,6 +712,8 @@ xfs_zone_gc_start_chunk(
>  	data->scratch_head = (data->scratch_head + len) % data->scratch_size;
>  	data->scratch_available -= len;
>  
> +	XFS_STATS_INC(mp, xs_gc_read_calls);
> +
>  	WRITE_ONCE(chunk->state, XFS_GC_BIO_NEW);
>  	list_add_tail(&chunk->entry, &data->reading);
>  	xfs_zone_gc_iter_advance(iter, irec.rm_blockcount);
> @@ -815,6 +817,9 @@ xfs_zone_gc_write_chunk(
>  		return;
>  	}
>  
> +	XFS_STATS_INC(mp, xs_gc_write_calls);
> +	XFS_STATS_ADD(mp, xs_gc_write_bytes, chunk->len);
> +
>  	WRITE_ONCE(chunk->state, XFS_GC_BIO_NEW);
>  	list_move_tail(&chunk->entry, &data->writing);
>  
> @@ -911,6 +916,8 @@ xfs_submit_zone_reset_bio(
>  		return;
>  	}
>  
> +	XFS_STATS_INC(mp, xs_gc_zone_reset_calls);
> +
>  	bio->bi_iter.bi_sector = xfs_gbno_to_daddr(&rtg->rtg_group, 0);
>  	if (!bdev_zone_is_seq(bio->bi_bdev, bio->bi_iter.bi_sector)) {
>  		/*
> -- 
> 2.47.3
> 
>