xfs: add sysfs stats for zoned GC

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>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Christoph Hellwig

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	xs_defer_relog = 0;
+	uint64_t	xs_gc_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;
 		xs_defer_relog += per_cpu_ptr(stats, i)->s.xs_defer_relog;
+		xs_gc_bytes += per_cpu_ptr(stats, i)->s.xs_gc_bytes;
 	}
 
 	len += scnprintf(buf + len, PATH_MAX-len, "xpc %llu %llu %llu\n",
@@ -89,6 +92,7 @@ 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_bytes);
 
 	return len;
 }

fs/xfs/xfs_stats.h

@@ -138,11 +138,17 @@ 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_defer_relog;
+	uint64_t		xs_gc_bytes;
 };
 
 #define	xfsstats_offset(f)	(offsetof(struct __xfsstats, f)/sizeof(uint32_t))

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_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)) {
 		/*