xfs: use offsetof() in place of offset macros for __xfsstats

Most offset macro mess is used in xfs_stats_format() only, and we can
simply get the right offsets using offsetof(), instead of several macros
to mark the offsets inside __xfsstats structure.

Replace all XFSSTAT_END_* macros by a single helper macro to get the
right offset into __xfsstats, and use this helper in xfs_stats_format()
directly.

The quota stats code, still looks a bit cleaner when using XFSSTAT_*
macros, so, this patch also defines XFSSTAT_START_XQMSTAT and
XFSSTAT_END_XQMSTAT locally to that code. This also should prevent
offset mistakes when updates are done into __xfsstats.

Signed-off-by: Carlos Maiolino <[e-mail]>
Reviewed-by: Darrick J. Wong <[e-mail]>
Signed-off-by: Dave Chinner <[e-mail]>

fs/xfs/xfs_stats.c

···
 		char	*desc;
 		int	endpoint;
 	} xstats[] = {
-		{ "extent_alloc",	XFSSTAT_END_EXTENT_ALLOC	},
-		{ "abt",		XFSSTAT_END_ALLOC_BTREE		},
-		{ "blk_map",		XFSSTAT_END_BLOCK_MAPPING	},
-		{ "bmbt",		XFSSTAT_END_BLOCK_MAP_BTREE	},
-		{ "dir",		XFSSTAT_END_DIRECTORY_OPS	},
-		{ "trans",		XFSSTAT_END_TRANSACTIONS	},
-		{ "ig",			XFSSTAT_END_INODE_OPS		},
-		{ "log",		XFSSTAT_END_LOG_OPS		},
-		{ "push_ail",		XFSSTAT_END_TAIL_PUSHING	},
-		{ "xstrat",		XFSSTAT_END_WRITE_CONVERT	},
-		{ "rw",			XFSSTAT_END_READ_WRITE_OPS	},
-		{ "attr",		XFSSTAT_END_ATTRIBUTE_OPS	},
-		{ "icluster",		XFSSTAT_END_INODE_CLUSTER	},
-		{ "vnodes",		XFSSTAT_END_VNODE_OPS		},
-		{ "buf",		XFSSTAT_END_BUF			},
-		{ "abtb2",		XFSSTAT_END_ABTB_V2		},
-		{ "abtc2",		XFSSTAT_END_ABTC_V2		},
-		{ "bmbt2",		XFSSTAT_END_BMBT_V2		},
-		{ "ibt2",		XFSSTAT_END_IBT_V2		},
-		{ "fibt2",		XFSSTAT_END_FIBT_V2		},
-		{ "rmapbt",		XFSSTAT_END_RMAP_V2		},
-		{ "refcntbt",		XFSSTAT_END_REFCOUNT		},
+		{ "extent_alloc",	xfsstats_offset(xs_abt_lookup)	},
+		{ "abt",		xfsstats_offset(xs_blk_mapr)	},
+		{ "blk_map",		xfsstats_offset(xs_bmbt_lookup)	},
+		{ "bmbt",		xfsstats_offset(xs_dir_lookup)	},
+		{ "dir",		xfsstats_offset(xs_trans_sync)	},
+		{ "trans",		xfsstats_offset(xs_ig_attempts)	},
+		{ "ig",			xfsstats_offset(xs_log_writes)	},
+		{ "log",		xfsstats_offset(xs_try_logspace)},
+		{ "push_ail",		xfsstats_offset(xs_xstrat_quick)},
+		{ "xstrat",		xfsstats_offset(xs_write_calls)	},
+		{ "rw",			xfsstats_offset(xs_attr_get)	},
+		{ "attr",		xfsstats_offset(xs_iflush_count)},
+		{ "icluster",		xfsstats_offset(vn_active)	},
+		{ "vnodes",		xfsstats_offset(xb_get)		},
+		{ "buf",		xfsstats_offset(xs_abtb_2)	},
+		{ "abtb2",		xfsstats_offset(xs_abtc_2)	},
+		{ "abtc2",		xfsstats_offset(xs_bmbt_2)	},
+		{ "bmbt2",		xfsstats_offset(xs_ibt_2)	},
+		{ "ibt2",		xfsstats_offset(xs_fibt_2)	},
+		{ "fibt2",		xfsstats_offset(xs_rmap_2)	},
+		{ "rmapbt",		xfsstats_offset(xs_refcbt_2)	},
+		{ "refcntbt",		xfsstats_offset(xs_qm_dqreclaims)},
 		/* we print both series of quota information together */
-		{ "qm",			XFSSTAT_END_QM			},
+		{ "qm",			xfsstats_offset(xs_xstrat_bytes)},
 	};
 
 	/* Loop over all stats groups */
···
 #ifdef CONFIG_PROC_FS
 /* legacy quota interfaces */
 #ifdef CONFIG_XFS_QUOTA
+
+#define XFSSTAT_START_XQMSTAT xfsstats_offset(xs_qm_dqreclaims)
+#define XFSSTAT_END_XQMSTAT xfsstats_offset(xs_qm_dquot)
+
 static int xqm_proc_show(struct seq_file *m, void *v)
 {
 	/* maximum; incore; ratio free to inuse; freelist */
···
 	int j;
 
 	seq_printf(m, "qm");
-	for (j = XFSSTAT_END_REFCOUNT; j < XFSSTAT_END_XQMSTAT; j++)
+	for (j = XFSSTAT_START_XQMSTAT; j < XFSSTAT_END_XQMSTAT; j++)
 		seq_printf(m, " %u", counter_val(xfsstats.xs_stats, j));
 	seq_putc(m, '\n');
 	return 0;

fs/xfs/xfs_stats.h

···
  * XFS global statistics
  */
 struct __xfsstats {
-# define XFSSTAT_END_EXTENT_ALLOC	4
 	uint32_t		xs_allocx;
 	uint32_t		xs_allocb;
 	uint32_t		xs_freex;
 	uint32_t		xs_freeb;
-# define XFSSTAT_END_ALLOC_BTREE	(XFSSTAT_END_EXTENT_ALLOC+4)
 	uint32_t		xs_abt_lookup;
 	uint32_t		xs_abt_compare;
 	uint32_t		xs_abt_insrec;
 	uint32_t		xs_abt_delrec;
-# define XFSSTAT_END_BLOCK_MAPPING	(XFSSTAT_END_ALLOC_BTREE+7)
 	uint32_t		xs_blk_mapr;
 	uint32_t		xs_blk_mapw;
 	uint32_t		xs_blk_unmap;
···
 	uint32_t		xs_del_exlist;
 	uint32_t		xs_look_exlist;
 	uint32_t		xs_cmp_exlist;
-# define XFSSTAT_END_BLOCK_MAP_BTREE	(XFSSTAT_END_BLOCK_MAPPING+4)
 	uint32_t		xs_bmbt_lookup;
 	uint32_t		xs_bmbt_compare;
 	uint32_t		xs_bmbt_insrec;
 	uint32_t		xs_bmbt_delrec;
-# define XFSSTAT_END_DIRECTORY_OPS	(XFSSTAT_END_BLOCK_MAP_BTREE+4)
 	uint32_t		xs_dir_lookup;
 	uint32_t		xs_dir_create;
 	uint32_t		xs_dir_remove;
 	uint32_t		xs_dir_getdents;
-# define XFSSTAT_END_TRANSACTIONS	(XFSSTAT_END_DIRECTORY_OPS+3)
 	uint32_t		xs_trans_sync;
 	uint32_t		xs_trans_async;
 	uint32_t		xs_trans_empty;
-# define XFSSTAT_END_INODE_OPS		(XFSSTAT_END_TRANSACTIONS+7)
 	uint32_t		xs_ig_attempts;
 	uint32_t		xs_ig_found;
 	uint32_t		xs_ig_frecycle;
···
 	uint32_t		xs_ig_dup;
 	uint32_t		xs_ig_reclaims;
 	uint32_t		xs_ig_attrchg;
-# define XFSSTAT_END_LOG_OPS		(XFSSTAT_END_INODE_OPS+5)
 	uint32_t		xs_log_writes;
 	uint32_t		xs_log_blocks;
 	uint32_t		xs_log_noiclogs;
 	uint32_t		xs_log_force;
 	uint32_t		xs_log_force_sleep;
-# define XFSSTAT_END_TAIL_PUSHING	(XFSSTAT_END_LOG_OPS+10)
 	uint32_t		xs_try_logspace;
 	uint32_t		xs_sleep_logspace;
 	uint32_t		xs_push_ail;
···
 	uint32_t		xs_push_ail_flushing;
 	uint32_t		xs_push_ail_restarts;
 	uint32_t		xs_push_ail_flush;
-# define XFSSTAT_END_WRITE_CONVERT	(XFSSTAT_END_TAIL_PUSHING+2)
 	uint32_t		xs_xstrat_quick;
 	uint32_t		xs_xstrat_split;
-# define XFSSTAT_END_READ_WRITE_OPS	(XFSSTAT_END_WRITE_CONVERT+2)
 	uint32_t		xs_write_calls;
 	uint32_t		xs_read_calls;
-# define XFSSTAT_END_ATTRIBUTE_OPS	(XFSSTAT_END_READ_WRITE_OPS+4)
 	uint32_t		xs_attr_get;
 	uint32_t		xs_attr_set;
 	uint32_t		xs_attr_remove;
 	uint32_t		xs_attr_list;
-# define XFSSTAT_END_INODE_CLUSTER	(XFSSTAT_END_ATTRIBUTE_OPS+3)
 	uint32_t		xs_iflush_count;
 	uint32_t		xs_icluster_flushcnt;
 	uint32_t		xs_icluster_flushinode;
-# define XFSSTAT_END_VNODE_OPS		(XFSSTAT_END_INODE_CLUSTER+8)
 	uint32_t		vn_active;	/* # vnodes not on free lists */
 	uint32_t		vn_alloc;	/* # times vn_alloc called */
 	uint32_t		vn_get;		/* # times vn_get called */
···
 	uint32_t		vn_reclaim;	/* # times vn_reclaim called */
 	uint32_t		vn_remove;	/* # times vn_remove called */
 	uint32_t		vn_free;	/* # times vn_free called */
-#define XFSSTAT_END_BUF			(XFSSTAT_END_VNODE_OPS+9)
 	uint32_t		xb_get;
 	uint32_t		xb_create;
 	uint32_t		xb_get_locked;
···
 	uint32_t		xb_page_found;
 	uint32_t		xb_get_read;
 /* Version 2 btree counters */
-#define XFSSTAT_END_ABTB_V2		(XFSSTAT_END_BUF + __XBTS_MAX)
 	uint32_t		xs_abtb_2[__XBTS_MAX];
-#define XFSSTAT_END_ABTC_V2		(XFSSTAT_END_ABTB_V2 + __XBTS_MAX)
 	uint32_t		xs_abtc_2[__XBTS_MAX];
-#define XFSSTAT_END_BMBT_V2		(XFSSTAT_END_ABTC_V2 + __XBTS_MAX)
 	uint32_t		xs_bmbt_2[__XBTS_MAX];
-#define XFSSTAT_END_IBT_V2		(XFSSTAT_END_BMBT_V2 + __XBTS_MAX)
 	uint32_t		xs_ibt_2[__XBTS_MAX];
-#define XFSSTAT_END_FIBT_V2		(XFSSTAT_END_IBT_V2 + __XBTS_MAX)
 	uint32_t		xs_fibt_2[__XBTS_MAX];
-#define XFSSTAT_END_RMAP_V2		(XFSSTAT_END_FIBT_V2 + __XBTS_MAX)
 	uint32_t		xs_rmap_2[__XBTS_MAX];
-#define XFSSTAT_END_REFCOUNT		(XFSSTAT_END_RMAP_V2 + __XBTS_MAX)
 	uint32_t		xs_refcbt_2[__XBTS_MAX];
-#define XFSSTAT_END_XQMSTAT		(XFSSTAT_END_REFCOUNT + 6)
 	uint32_t		xs_qm_dqreclaims;
 	uint32_t		xs_qm_dqreclaim_misses;
 	uint32_t		xs_qm_dquot_dups;
 	uint32_t		xs_qm_dqcachemisses;
 	uint32_t		xs_qm_dqcachehits;
 	uint32_t		xs_qm_dqwants;
-#define XFSSTAT_END_QM			(XFSSTAT_END_XQMSTAT+2)
 	uint32_t		xs_qm_dquot;
 	uint32_t		xs_qm_dquot_unused;
 /* Extra precision counters */
···
 	uint64_t		xs_read_bytes;
 };
 
+#define	xfsstats_offset(f)	(offsetof(struct __xfsstats, f)/sizeof(uint32_t))
+
 struct xfsstats {
 	union {
 		struct __xfsstats	s;
-		uint32_t		a[XFSSTAT_END_XQMSTAT];
+		uint32_t		a[xfsstats_offset(xs_qm_dquot)];
 	};
 };