xfs: remove metafile inodes from the active inode stat

The active inode (or active vnode until recently) stat can get much larger
than expected on file systems with a lot of metafile inodes like zoned
file systems on SMR hard disks with 10.000s of rtg rmap inodes.

Remove all metafile inodes from the active counter to make it more useful
to track actual workloads and add a separate counter for active metafile
inodes.

This fixes xfs/177 on SMR hard drives.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Christoph Hellwig

fs/xfs/libxfs/xfs_inode_buf.c

@@ -268,6 +268,10 @@ xfs_inode_from_disk(
 	}
 	if (xfs_is_reflink_inode(ip))
 		xfs_ifork_init_cow(ip);
+	if (xfs_is_metadir_inode(ip)) {
+		XFS_STATS_DEC(ip->i_mount, xs_inodes_active);
+		XFS_STATS_INC(ip->i_mount, xs_inodes_meta);
+	}
 	return 0;
 
 out_destroy_data_fork:

fs/xfs/libxfs/xfs_metafile.c

@@ -61,6 +61,9 @@ xfs_metafile_set_iflag(
 	ip->i_diflags2 |= XFS_DIFLAG2_METADATA;
 	ip->i_metatype = metafile_type;
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+
+	XFS_STATS_DEC(ip->i_mount, xs_inodes_active);
+	XFS_STATS_INC(ip->i_mount, xs_inodes_meta);
 }
 
 /* Clear the metadata directory inode flag. */
@@ -74,6 +77,8 @@ xfs_metafile_clear_iflag(
 
 	ip->i_diflags2 &= ~XFS_DIFLAG2_METADATA;
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+	XFS_STATS_INC(ip->i_mount, xs_inodes_active);
+	XFS_STATS_DEC(ip->i_mount, xs_inodes_meta);
 }
 
 /*

fs/xfs/xfs_icache.c

@@ -172,7 +172,10 @@ __xfs_inode_free(
 	/* asserts to verify all state is correct here */
 	ASSERT(atomic_read(&ip->i_pincount) == 0);
 	ASSERT(!ip->i_itemp || list_empty(&ip->i_itemp->ili_item.li_bio_list));
-	XFS_STATS_DEC(ip->i_mount, xs_inodes_active);
+	if (xfs_is_metadir_inode(ip))
+		XFS_STATS_DEC(ip->i_mount, xs_inodes_meta);
+	else
+		XFS_STATS_DEC(ip->i_mount, xs_inodes_active);
 
 	call_rcu(&VFS_I(ip)->i_rcu, xfs_inode_free_callback);
 }

fs/xfs/xfs_stats.c

@@ -59,7 +59,8 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
 		{ "rtrefcntbt",		xfsstats_offset(xs_qm_dqreclaims)},
 		/* we print both series of quota information together */
 		{ "qm",			xfsstats_offset(xs_gc_read_calls)},
-		{ "zoned",		xfsstats_offset(__pad1)},
+		{ "zoned",		xfsstats_offset(xs_inodes_meta)},
+		{ "metafile",		xfsstats_offset(xs_xstrat_bytes)},
 	};
 
 	/* Loop over all stats groups */
@@ -99,16 +100,20 @@ int xfs_stats_format(struct xfsstats __percpu *stats, char *buf)
 
 void xfs_stats_clearall(struct xfsstats __percpu *stats)
 {
+	uint32_t	xs_inodes_active, xs_inodes_meta;
 	int		c;
-	uint32_t	xs_inodes_active;
 
 	xfs_notice(NULL, "Clearing xfsstats");
 	for_each_possible_cpu(c) {
 		preempt_disable();
-		/* save xs_inodes_active, it's a universal truth! */
+		/*
+		 * Save the active / meta inode counters, as they are stateful.
+		 */
 		xs_inodes_active = per_cpu_ptr(stats, c)->s.xs_inodes_active;
+		xs_inodes_meta = per_cpu_ptr(stats, c)->s.xs_inodes_meta;
 		memset(per_cpu_ptr(stats, c), 0, sizeof(*stats));
 		per_cpu_ptr(stats, c)->s.xs_inodes_active = xs_inodes_active;
+		per_cpu_ptr(stats, c)->s.xs_inodes_meta = xs_inodes_meta;
 		preempt_enable();
 	}
 }

fs/xfs/xfs_stats.h

@@ -142,7 +142,8 @@ struct __xfsstats {
 	uint32_t		xs_gc_read_calls;
 	uint32_t		xs_gc_write_calls;
 	uint32_t		xs_gc_zone_reset_calls;
-	uint32_t		__pad1;
+/* Metafile counters */
+	uint32_t		xs_inodes_meta;
 /* Extra precision counters */
 	uint64_t		xs_xstrat_bytes;
 	uint64_t		xs_write_bytes;