xfs: factor out a generic xfs_group structure

Split the lookup and refcount handling of struct xfs_perag into an
embedded xfs_group structure that can be reused for the upcoming
realtime groups.

It will be extended with more features later.

Note that he xg_type field will only need a single bit even with
realtime group support.  For now it fills a hole, but it might be
worth to fold it into another field if we can use this space better.

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

fs/xfs/Makefile

@@ -14,6 +14,7 @@ xfs-y				+= xfs_trace.o
 
 # build the libxfs code first
 xfs-y				+= $(addprefix libxfs/, \
+				   xfs_group.o \
 				   xfs_ag.o \
 				   xfs_alloc.o \
 				   xfs_alloc_btree.o \

fs/xfs/libxfs/xfs_ag.c

@@ -30,85 +30,7 @@
 #include "xfs_trace.h"
 #include "xfs_inode.h"
 #include "xfs_icache.h"
-
-
-/*
- * Passive reference counting access wrappers to the perag structures.  If the
- * per-ag structure is to be freed, the freeing code is responsible for cleaning
- * up objects with passive references before freeing the structure. This is
- * things like cached buffers.
- */
-struct xfs_perag *
-xfs_perag_get(
-	struct xfs_mount	*mp,
-	xfs_agnumber_t		agno)
-{
-	struct xfs_perag	*pag;
-
-	rcu_read_lock();
-	pag = xa_load(&mp->m_perags, agno);
-	if (pag) {
-		trace_xfs_perag_get(pag, _RET_IP_);
-		ASSERT(atomic_read(&pag->pag_ref) >= 0);
-		atomic_inc(&pag->pag_ref);
-	}
-	rcu_read_unlock();
-	return pag;
-}
-
-/* Get a passive reference to the given perag. */
-struct xfs_perag *
-xfs_perag_hold(
-	struct xfs_perag	*pag)
-{
-	ASSERT(atomic_read(&pag->pag_ref) > 0 ||
-	       atomic_read(&pag->pag_active_ref) > 0);
-
-	trace_xfs_perag_hold(pag, _RET_IP_);
-	atomic_inc(&pag->pag_ref);
-	return pag;
-}
-
-void
-xfs_perag_put(
-	struct xfs_perag	*pag)
-{
-	trace_xfs_perag_put(pag, _RET_IP_);
-	ASSERT(atomic_read(&pag->pag_ref) > 0);
-	atomic_dec(&pag->pag_ref);
-}
-
-/*
- * Active references for perag structures. This is for short term access to the
- * per ag structures for walking trees or accessing state. If an AG is being
- * shrunk or is offline, then this will fail to find that AG and return NULL
- * instead.
- */
-struct xfs_perag *
-xfs_perag_grab(
-	struct xfs_mount	*mp,
-	xfs_agnumber_t		agno)
-{
-	struct xfs_perag	*pag;
-
-	rcu_read_lock();
-	pag = xa_load(&mp->m_perags, agno);
-	if (pag) {
-		trace_xfs_perag_grab(pag, _RET_IP_);
-		if (!atomic_inc_not_zero(&pag->pag_active_ref))
-			pag = NULL;
-	}
-	rcu_read_unlock();
-	return pag;
-}
-
-void
-xfs_perag_rele(
-	struct xfs_perag	*pag)
-{
-	trace_xfs_perag_rele(pag, _RET_IP_);
-	atomic_dec(&pag->pag_active_ref);
-}
+#include "xfs_group.h"
 
 /*
  * xfs_initialize_perag_data
@@ -183,6 +105,19 @@ out:
 	return error;
 }
 
+static void
+xfs_perag_uninit(
+	struct xfs_group	*xg)
+{
+#ifdef __KERNEL__
+	struct xfs_perag	*pag = to_perag(xg);
+
+	xfs_defer_drain_free(&pag->pag_intents_drain);
+	cancel_delayed_work_sync(&pag->pag_blockgc_work);
+	xfs_buf_cache_destroy(&pag->pag_bcache);
+#endif
+}
+
 /*
  * Free up the per-ag resources  within the specified AG range.
  */
@@ -195,22 +130,8 @@ xfs_free_perag_range(
 {
 	xfs_agnumber_t		agno;
 
-	for (agno = first_agno; agno < end_agno; agno++) {
-		struct xfs_perag	*pag = xa_erase(&mp->m_perags, agno);
-
-		ASSERT(pag);
-		XFS_IS_CORRUPT(pag->pag_mount, atomic_read(&pag->pag_ref) != 0);
-		xfs_defer_drain_free(&pag->pag_intents_drain);
-
-		cancel_delayed_work_sync(&pag->pag_blockgc_work);
-		xfs_buf_cache_destroy(&pag->pag_bcache);
-
-		/* drop the mount's active reference */
-		xfs_perag_rele(pag);
-		XFS_IS_CORRUPT(pag->pag_mount,
-				atomic_read(&pag->pag_active_ref) != 0);
-		kfree_rcu_mightsleep(pag);
-	}
+	for (agno = first_agno; agno < end_agno; agno++)
+		xfs_group_free(mp, agno, XG_TYPE_AG, xfs_perag_uninit);
 }
 
 /* Find the size of the AG, in blocks. */
@@ -332,16 +253,9 @@ xfs_perag_alloc(
 	__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
 			&pag->agino_max);
 
-	pag->pag_agno = index;
-	pag->pag_mount = mp;
-	/* Active ref owned by mount indicates AG is online. */
-	atomic_set(&pag->pag_active_ref, 1);
-
-	error = xa_insert(&mp->m_perags, index, pag, GFP_KERNEL);
-	if (error) {
-		WARN_ON_ONCE(error == -EBUSY);
+	error = xfs_group_insert(mp, pag_group(pag), index, XG_TYPE_AG);
+	if (error)
 		goto out_buf_cache_destroy;
-	}
 
 	return 0;
 
@@ -833,7 +747,7 @@ xfs_ag_shrink_space(
 	struct xfs_trans	**tpp,
 	xfs_extlen_t		delta)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	struct xfs_alloc_arg	args = {
 		.tp	= *tpp,
 		.mp	= mp,
@@ -850,7 +764,7 @@ xfs_ag_shrink_space(
 	xfs_agblock_t		aglen;
 	int			error, err2;
 
-	ASSERT(pag->pag_agno == mp->m_sb.sb_agcount - 1);
+	ASSERT(pag_agno(pag) == mp->m_sb.sb_agcount - 1);
 	error = xfs_ialloc_read_agi(pag, *tpp, 0, &agibp);
 	if (error)
 		return error;
@@ -947,8 +861,8 @@ xfs_ag_shrink_space(
 
 	/* Update perag geometry */
 	pag->block_count -= delta;
-	__xfs_agino_range(pag->pag_mount, pag->block_count, &pag->agino_min,
-				&pag->agino_max);
+	__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
+			&pag->agino_max);
 
 	xfs_ialloc_log_agi(*tpp, agibp, XFS_AGI_LENGTH);
 	xfs_alloc_log_agf(*tpp, agfbp, XFS_AGF_LENGTH);
@@ -973,12 +887,13 @@ xfs_ag_extend_space(
 	struct xfs_trans	*tp,
 	xfs_extlen_t		len)
 {
+	struct xfs_mount	*mp = pag_mount(pag);
 	struct xfs_buf		*bp;
 	struct xfs_agi		*agi;
 	struct xfs_agf		*agf;
 	int			error;
 
-	ASSERT(pag->pag_agno == pag->pag_mount->m_sb.sb_agcount - 1);
+	ASSERT(pag_agno(pag) == mp->m_sb.sb_agcount - 1);
 
 	error = xfs_ialloc_read_agi(pag, tp, 0, &bp);
 	if (error)
@@ -1018,8 +933,8 @@ xfs_ag_extend_space(
 
 	/* Update perag geometry */
 	pag->block_count = be32_to_cpu(agf->agf_length);
-	__xfs_agino_range(pag->pag_mount, pag->block_count, &pag->agino_min,
-				&pag->agino_max);
+	__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
+			&pag->agino_max);
 	return 0;
 }
 
@@ -1046,7 +961,7 @@ xfs_ag_get_geometry(
 
 	/* Fill out form. */
 	memset(ageo, 0, sizeof(*ageo));
-	ageo->ag_number = pag->pag_agno;
+	ageo->ag_number = pag_agno(pag);
 
 	agi = agi_bp->b_addr;
 	ageo->ag_icount = be32_to_cpu(agi->agi_count);

fs/xfs/libxfs/xfs_ag.h

@@ -7,6 +7,8 @@
 #ifndef __LIBXFS_AG_H
 #define __LIBXFS_AG_H 1
 
+#include "xfs_group.h"
+
 struct xfs_mount;
 struct xfs_trans;
 struct xfs_perag;
@@ -30,10 +32,7 @@ struct xfs_ag_resv {
  * performance of allocation group selection.
  */
 struct xfs_perag {
-	struct xfs_mount *pag_mount;	/* owner filesystem */
-	xfs_agnumber_t	pag_agno;	/* AG this structure belongs to */
-	atomic_t	pag_ref;	/* passive reference count */
-	atomic_t	pag_active_ref;	/* active reference count */
+	struct xfs_group pag_group;
 	unsigned long	pag_opstate;
 	uint8_t		pagf_bno_level;	/* # of levels in bno btree */
 	uint8_t		pagf_cnt_level;	/* # of levels in cnt btree */
@@ -121,6 +120,26 @@ struct xfs_perag {
 #endif /* __KERNEL__ */
 };
 
+static inline struct xfs_perag *to_perag(struct xfs_group *xg)
+{
+	return container_of(xg, struct xfs_perag, pag_group);
+}
+
+static inline struct xfs_group *pag_group(struct xfs_perag *pag)
+{
+	return &pag->pag_group;
+}
+
+static inline struct xfs_mount *pag_mount(const struct xfs_perag *pag)
+{
+	return pag->pag_group.xg_mount;
+}
+
+static inline xfs_agnumber_t pag_agno(const struct xfs_perag *pag)
+{
+	return pag->pag_group.xg_gno;
+}
+
 /*
  * Per-AG operational state. These are atomic flag bits.
  */
@@ -151,13 +170,43 @@ int xfs_initialize_perag_data(struct xfs_mount *mp, xfs_agnumber_t agno);
 int xfs_update_last_ag_size(struct xfs_mount *mp, xfs_agnumber_t prev_agcount);
 
 /* Passive AG references */
-struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
-struct xfs_perag *xfs_perag_hold(struct xfs_perag *pag);
-void xfs_perag_put(struct xfs_perag *pag);
+static inline struct xfs_perag *
+xfs_perag_get(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno)
+{
+	return to_perag(xfs_group_get(mp, agno, XG_TYPE_AG));
+}
+
+static inline struct xfs_perag *
+xfs_perag_hold(
+	struct xfs_perag	*pag)
+{
+	return to_perag(xfs_group_hold(pag_group(pag)));
+}
+
+static inline void
+xfs_perag_put(
+	struct xfs_perag	*pag)
+{
+	xfs_group_put(pag_group(pag));
+}
 
 /* Active AG references */
-struct xfs_perag *xfs_perag_grab(struct xfs_mount *, xfs_agnumber_t);
-void xfs_perag_rele(struct xfs_perag *pag);
+static inline struct xfs_perag *
+xfs_perag_grab(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		agno)
+{
+	return to_perag(xfs_group_grab(mp, agno, XG_TYPE_AG));
+}
+
+static inline void
+xfs_perag_rele(
+	struct xfs_perag	*pag)
+{
+	xfs_group_rele(pag_group(pag));
+}
 
 /*
  * Per-ag geometry infomation and validation
@@ -233,9 +282,9 @@ xfs_perag_next(
 	xfs_agnumber_t		*agno,
 	xfs_agnumber_t		end_agno)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 
-	*agno = pag->pag_agno + 1;
+	*agno = pag_agno(pag) + 1;
 	xfs_perag_rele(pag);
 	while (*agno <= end_agno) {
 		pag = xfs_perag_grab(mp, *agno);
@@ -266,9 +315,9 @@ xfs_perag_next_wrap(
 	xfs_agnumber_t		restart_agno,
 	xfs_agnumber_t		wrap_agno)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 
-	*agno = pag->pag_agno + 1;
+	*agno = pag_agno(pag) + 1;
 	xfs_perag_rele(pag);
 	while (*agno != stop_agno) {
 		if (*agno >= wrap_agno) {
@@ -335,7 +384,7 @@ xfs_agbno_to_fsb(
 	struct xfs_perag	*pag,
 	xfs_agblock_t		agbno)
 {
-	return XFS_AGB_TO_FSB(pag->pag_mount, pag->pag_agno, agbno);
+	return XFS_AGB_TO_FSB(pag_mount(pag), pag_agno(pag), agbno);
 }
 
 static inline xfs_daddr_t
@@ -343,7 +392,7 @@ xfs_agbno_to_daddr(
 	struct xfs_perag	*pag,
 	xfs_agblock_t		agbno)
 {
-	return XFS_AGB_TO_DADDR(pag->pag_mount, pag->pag_agno, agbno);
+	return XFS_AGB_TO_DADDR(pag_mount(pag), pag_agno(pag), agbno);
 }
 
 static inline xfs_ino_t
@@ -351,7 +400,7 @@ xfs_agino_to_ino(
 	struct xfs_perag	*pag,
 	xfs_agino_t		agino)
 {
-	return XFS_AGINO_TO_INO(pag->pag_mount, pag->pag_agno, agino);
+	return XFS_AGINO_TO_INO(pag_mount(pag), pag_agno(pag), agino);
 }
 
 #endif /* __LIBXFS_AG_H */

fs/xfs/libxfs/xfs_ag_resv.c

@@ -70,6 +70,7 @@ xfs_ag_resv_critical(
 	struct xfs_perag		*pag,
 	enum xfs_ag_resv_type		type)
 {
+	struct xfs_mount		*mp = pag_mount(pag);
 	xfs_extlen_t			avail;
 	xfs_extlen_t			orig;
 
@@ -92,8 +93,8 @@ xfs_ag_resv_critical(
 
 	/* Critically low if less than 10% or max btree height remains. */
 	return XFS_TEST_ERROR(avail < orig / 10 ||
-			      avail < pag->pag_mount->m_agbtree_maxlevels,
-			pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL);
+			      avail < mp->m_agbtree_maxlevels,
+			mp, XFS_ERRTAG_AG_RESV_CRITICAL);
 }
 
 /*
@@ -137,8 +138,8 @@ __xfs_ag_resv_free(
 	trace_xfs_ag_resv_free(pag, type, 0);
 
 	resv = xfs_perag_resv(pag, type);
-	if (pag->pag_agno == 0)
-		pag->pag_mount->m_ag_max_usable += resv->ar_asked;
+	if (pag_agno(pag) == 0)
+		pag_mount(pag)->m_ag_max_usable += resv->ar_asked;
 	/*
 	 * RMAPBT blocks come from the AGFL and AGFL blocks are always
 	 * considered "free", so whatever was reserved at mount time must be
@@ -148,7 +149,7 @@ __xfs_ag_resv_free(
 		oldresv = resv->ar_orig_reserved;
 	else
 		oldresv = resv->ar_reserved;
-	xfs_add_fdblocks(pag->pag_mount, oldresv);
+	xfs_add_fdblocks(pag_mount(pag), oldresv);
 	resv->ar_reserved = 0;
 	resv->ar_asked = 0;
 	resv->ar_orig_reserved = 0;
@@ -170,7 +171,7 @@ __xfs_ag_resv_init(
 	xfs_extlen_t			ask,
 	xfs_extlen_t			used)
 {
-	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_mount		*mp = pag_mount(pag);
 	struct xfs_ag_resv		*resv;
 	int				error;
 	xfs_extlen_t			hidden_space;
@@ -209,7 +210,7 @@ __xfs_ag_resv_init(
 		trace_xfs_ag_resv_init_error(pag, error, _RET_IP_);
 		xfs_warn(mp,
 "Per-AG reservation for AG %u failed.  Filesystem may run out of space.",
-				pag->pag_agno);
+				pag_agno(pag));
 		return error;
 	}
 
@@ -219,7 +220,7 @@ __xfs_ag_resv_init(
 	 * counter, we only make the adjustment for AG 0.  This assumes that
 	 * there aren't any AGs hungrier for per-AG reservation than AG 0.
 	 */
-	if (pag->pag_agno == 0)
+	if (pag_agno(pag) == 0)
 		mp->m_ag_max_usable -= ask;
 
 	resv = xfs_perag_resv(pag, type);
@@ -237,7 +238,7 @@ xfs_ag_resv_init(
 	struct xfs_perag		*pag,
 	struct xfs_trans		*tp)
 {
-	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_mount		*mp = pag_mount(pag);
 	xfs_extlen_t			ask;
 	xfs_extlen_t			used;
 	int				error = 0, error2;

fs/xfs/libxfs/xfs_alloc.c

@@ -275,7 +275,7 @@ xfs_alloc_complain_bad_rec(
 
 	xfs_warn(mp,
 		"%sbt record corruption in AG %d detected at %pS!",
-		cur->bc_ops->name, cur->bc_ag.pag->pag_agno, fa);
+		cur->bc_ops->name, pag_agno(cur->bc_ag.pag), fa);
 	xfs_warn(mp,
 		"start block 0x%x block count 0x%x", irec->ar_startblock,
 		irec->ar_blockcount);
@@ -799,7 +799,7 @@ xfs_agfl_verify(
 	 * use it by using uncached buffers that don't have the perag attached
 	 * so we can detect and avoid this problem.
 	 */
-	if (bp->b_pag && be32_to_cpu(agfl->agfl_seqno) != bp->b_pag->pag_agno)
+	if (bp->b_pag && be32_to_cpu(agfl->agfl_seqno) != pag_agno((bp->b_pag)))
 		return __this_address;
 
 	for (i = 0; i < xfs_agfl_size(mp); i++) {
@@ -879,13 +879,12 @@ xfs_alloc_read_agfl(
 	struct xfs_trans	*tp,
 	struct xfs_buf		**bpp)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	struct xfs_buf		*bp;
 	int			error;
 
-	error = xfs_trans_read_buf(
-			mp, tp, mp->m_ddev_targp,
-			XFS_AG_DADDR(mp, pag->pag_agno, XFS_AGFL_DADDR(mp)),
+	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
+			XFS_AG_DADDR(mp, pag_agno(pag), XFS_AGFL_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), 0, &bp, &xfs_agfl_buf_ops);
 	if (xfs_metadata_is_sick(error))
 		xfs_ag_mark_sick(pag, XFS_SICK_AG_AGFL);
@@ -2428,7 +2427,7 @@ xfs_alloc_longest_free_extent(
 	 * reservations and AGFL rules in place, we can return this extent.
 	 */
 	if (pag->pagf_longest > delta)
-		return min_t(xfs_extlen_t, pag->pag_mount->m_ag_max_usable,
+		return min_t(xfs_extlen_t, pag_mount(pag)->m_ag_max_usable,
 				pag->pagf_longest - delta);
 
 	/* Otherwise, let the caller try for 1 block if there's space. */
@@ -2611,7 +2610,7 @@ xfs_agfl_reset(
 	xfs_warn(mp,
 	       "WARNING: Reset corrupted AGFL on AG %u. %d blocks leaked. "
 	       "Please unmount and run xfs_repair.",
-	         pag->pag_agno, pag->pagf_flcount);
+		pag_agno(pag), pag->pagf_flcount);
 
 	agf->agf_flfirst = 0;
 	agf->agf_fllast = cpu_to_be32(xfs_agfl_size(mp) - 1);
@@ -3188,7 +3187,7 @@ xfs_validate_ag_length(
 	 * use it by using uncached buffers that don't have the perag attached
 	 * so we can detect and avoid this problem.
 	 */
-	if (bp->b_pag && seqno != bp->b_pag->pag_agno)
+	if (bp->b_pag && seqno != pag_agno(bp->b_pag))
 		return __this_address;
 
 	/*
@@ -3357,13 +3356,13 @@ xfs_read_agf(
 	int			flags,
 	struct xfs_buf		**agfbpp)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	int			error;
 
 	trace_xfs_read_agf(pag);
 
 	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
-			XFS_AG_DADDR(mp, pag->pag_agno, XFS_AGF_DADDR(mp)),
+			XFS_AG_DADDR(mp, pag_agno(pag), XFS_AGF_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), flags, agfbpp, &xfs_agf_buf_ops);
 	if (xfs_metadata_is_sick(error))
 		xfs_ag_mark_sick(pag, XFS_SICK_AG_AGF);
@@ -3386,6 +3385,7 @@ xfs_alloc_read_agf(
 	int			flags,
 	struct xfs_buf		**agfbpp)
 {
+	struct xfs_mount	*mp = pag_mount(pag);
 	struct xfs_buf		*agfbp;
 	struct xfs_agf		*agf;
 	int			error;
@@ -3412,7 +3412,7 @@ xfs_alloc_read_agf(
 		pag->pagf_cnt_level = be32_to_cpu(agf->agf_cnt_level);
 		pag->pagf_rmap_level = be32_to_cpu(agf->agf_rmap_level);
 		pag->pagf_refcount_level = be32_to_cpu(agf->agf_refcount_level);
-		if (xfs_agfl_needs_reset(pag->pag_mount, agf))
+		if (xfs_agfl_needs_reset(mp, agf))
 			set_bit(XFS_AGSTATE_AGFL_NEEDS_RESET, &pag->pag_opstate);
 		else
 			clear_bit(XFS_AGSTATE_AGFL_NEEDS_RESET, &pag->pag_opstate);
@@ -3425,16 +3425,15 @@ xfs_alloc_read_agf(
 		 * counter only tracks non-root blocks.
 		 */
 		allocbt_blks = pag->pagf_btreeblks;
-		if (xfs_has_rmapbt(pag->pag_mount))
+		if (xfs_has_rmapbt(mp))
 			allocbt_blks -= be32_to_cpu(agf->agf_rmap_blocks) - 1;
 		if (allocbt_blks > 0)
-			atomic64_add(allocbt_blks,
-					&pag->pag_mount->m_allocbt_blks);
+			atomic64_add(allocbt_blks, &mp->m_allocbt_blks);
 
 		set_bit(XFS_AGSTATE_AGF_INIT, &pag->pag_opstate);
 	}
 #ifdef DEBUG
-	else if (!xfs_is_shutdown(pag->pag_mount)) {
+	else if (!xfs_is_shutdown(mp)) {
 		ASSERT(pag->pagf_freeblks == be32_to_cpu(agf->agf_freeblks));
 		ASSERT(pag->pagf_btreeblks == be32_to_cpu(agf->agf_btreeblks));
 		ASSERT(pag->pagf_flcount == be32_to_cpu(agf->agf_flcount));
@@ -3652,7 +3651,7 @@ xfs_alloc_vextent_this_ag(
 	int			error;
 
 	ASSERT(args->pag != NULL);
-	ASSERT(args->pag->pag_agno == agno);
+	ASSERT(pag_agno(args->pag) == agno);
 
 	args->agno = agno;
 	args->agbno = 0;
@@ -3865,7 +3864,7 @@ xfs_alloc_vextent_exact_bno(
 	int			error;
 
 	ASSERT(args->pag != NULL);
-	ASSERT(args->pag->pag_agno == XFS_FSB_TO_AGNO(mp, target));
+	ASSERT(pag_agno(args->pag) == XFS_FSB_TO_AGNO(mp, target));
 
 	args->agno = XFS_FSB_TO_AGNO(mp, target);
 	args->agbno = XFS_FSB_TO_AGBNO(mp, target);
@@ -3904,7 +3903,7 @@ xfs_alloc_vextent_near_bno(
 	int			error;
 
 	if (!needs_perag)
-		ASSERT(args->pag->pag_agno == XFS_FSB_TO_AGNO(mp, target));
+		ASSERT(pag_agno(args->pag) == XFS_FSB_TO_AGNO(mp, target));
 
 	args->agno = XFS_FSB_TO_AGNO(mp, target);
 	args->agbno = XFS_FSB_TO_AGBNO(mp, target);
@@ -3941,7 +3940,7 @@ xfs_free_extent_fix_freelist(
 	memset(&args, 0, sizeof(struct xfs_alloc_arg));
 	args.tp = tp;
 	args.mp = tp->t_mountp;
-	args.agno = pag->pag_agno;
+	args.agno = pag_agno(pag);
 	args.pag = pag;
 
 	/*

fs/xfs/libxfs/xfs_alloc_btree.c

@@ -178,7 +178,7 @@ xfs_allocbt_init_ptr_from_cur(
 {
 	struct xfs_agf		*agf = cur->bc_ag.agbp->b_addr;
 
-	ASSERT(cur->bc_ag.pag->pag_agno == be32_to_cpu(agf->agf_seqno));
+	ASSERT(pag_agno(cur->bc_ag.pag) == be32_to_cpu(agf->agf_seqno));
 
 	if (xfs_btree_is_bno(cur->bc_ops))
 		ptr->s = agf->agf_bno_root;

fs/xfs/libxfs/xfs_bmap.c

@@ -3280,7 +3280,7 @@ xfs_bmap_longest_free_extent(
 	}
 
 	longest = xfs_alloc_longest_free_extent(pag,
-				xfs_alloc_min_freelist(pag->pag_mount, pag),
+				xfs_alloc_min_freelist(pag_mount(pag), pag),
 				xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE));
 	if (*blen < longest)
 		*blen = longest;

fs/xfs/libxfs/xfs_btree.c

@@ -372,7 +372,7 @@ xfs_btree_check_ptr(
 		case XFS_BTREE_TYPE_AG:
 			xfs_err(cur->bc_mp,
 "AG %u: Corrupt %sbt pointer at level %d index %d.",
-				cur->bc_ag.pag->pag_agno, cur->bc_ops->name,
+				pag_agno(cur->bc_ag.pag), cur->bc_ops->name,
 				level, index);
 			break;
 		}
@@ -1312,7 +1312,7 @@ xfs_btree_owner(
 	case XFS_BTREE_TYPE_INODE:
 		return cur->bc_ino.ip->i_ino;
 	case XFS_BTREE_TYPE_AG:
-		return cur->bc_ag.pag->pag_agno;
+		return pag_agno(cur->bc_ag.pag);
 	default:
 		ASSERT(0);
 		return 0;
@@ -4744,7 +4744,7 @@ xfs_btree_agblock_v5hdr_verify(
 		return __this_address;
 	if (block->bb_u.s.bb_blkno != cpu_to_be64(xfs_buf_daddr(bp)))
 		return __this_address;
-	if (pag && be32_to_cpu(block->bb_u.s.bb_owner) != pag->pag_agno)
+	if (pag && be32_to_cpu(block->bb_u.s.bb_owner) != pag_agno(pag))
 		return __this_address;
 	return NULL;
 }

fs/xfs/libxfs/xfs_group.c

@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Red Hat, Inc.
+ */
+
+#include "xfs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_group.h"
+
+/*
+ * Groups can have passive and active references.
+ *
+ * For passive references the code freeing a group is responsible for cleaning
+ * up objects that hold the passive references (e.g. cached buffers).
+ * Routines manipulating passive references are xfs_group_get, xfs_group_hold
+ * and xfs_group_put.
+ *
+ * Active references are for short term access to the group for walking trees or
+ * accessing state. If a group is being shrunk or offlined, the lookup will fail
+ * to find that group and return NULL instead.
+ * Routines manipulating active references are xfs_group_grab and
+ * xfs_group_rele.
+ */
+
+struct xfs_group *
+xfs_group_get(
+	struct xfs_mount	*mp,
+	uint32_t		index,
+	enum xfs_group_type	type)
+{
+	struct xfs_group	*xg;
+
+	rcu_read_lock();
+	xg = xa_load(&mp->m_groups[type].xa, index);
+	if (xg) {
+		trace_xfs_group_get(xg, _RET_IP_);
+		ASSERT(atomic_read(&xg->xg_ref) >= 0);
+		atomic_inc(&xg->xg_ref);
+	}
+	rcu_read_unlock();
+	return xg;
+}
+
+struct xfs_group *
+xfs_group_hold(
+	struct xfs_group	*xg)
+{
+	ASSERT(atomic_read(&xg->xg_ref) > 0 ||
+	       atomic_read(&xg->xg_active_ref) > 0);
+
+	trace_xfs_group_hold(xg, _RET_IP_);
+	atomic_inc(&xg->xg_ref);
+	return xg;
+}
+
+void
+xfs_group_put(
+	struct xfs_group	*xg)
+{
+	trace_xfs_group_put(xg, _RET_IP_);
+
+	ASSERT(atomic_read(&xg->xg_ref) > 0);
+	atomic_dec(&xg->xg_ref);
+}
+
+struct xfs_group *
+xfs_group_grab(
+	struct xfs_mount	*mp,
+	uint32_t		index,
+	enum xfs_group_type	type)
+{
+	struct xfs_group	*xg;
+
+	rcu_read_lock();
+	xg = xa_load(&mp->m_groups[type].xa, index);
+	if (xg) {
+		trace_xfs_group_grab(xg, _RET_IP_);
+		if (!atomic_inc_not_zero(&xg->xg_active_ref))
+			xg = NULL;
+	}
+	rcu_read_unlock();
+	return xg;
+}
+
+/*
+ * Find the next group after @xg, or the first group if @xg is NULL.
+ */
+struct xfs_group *
+xfs_group_grab_next_mark(
+	struct xfs_mount	*mp,
+	struct xfs_group	*xg,
+	xa_mark_t		mark,
+	enum xfs_group_type	type)
+{
+	unsigned long		index = 0;
+
+	if (xg) {
+		index = xg->xg_gno + 1;
+		xfs_group_rele(xg);
+	}
+
+	rcu_read_lock();
+	xg = xa_find(&mp->m_groups[type].xa, &index, ULONG_MAX, mark);
+	if (xg) {
+		trace_xfs_group_grab_next_tag(xg, _RET_IP_);
+		if (!atomic_inc_not_zero(&xg->xg_active_ref))
+			xg = NULL;
+	}
+	rcu_read_unlock();
+	return xg;
+}
+
+void
+xfs_group_rele(
+	struct xfs_group	*xg)
+{
+	trace_xfs_group_rele(xg, _RET_IP_);
+	atomic_dec(&xg->xg_active_ref);
+}
+
+void
+xfs_group_free(
+	struct xfs_mount	*mp,
+	uint32_t		index,
+	enum xfs_group_type	type,
+	void			(*uninit)(struct xfs_group *xg))
+{
+	struct xfs_group	*xg = xa_erase(&mp->m_groups[type].xa, index);
+
+	XFS_IS_CORRUPT(mp, atomic_read(&xg->xg_ref) != 0);
+
+	if (uninit)
+		uninit(xg);
+
+	/* drop the mount's active reference */
+	xfs_group_rele(xg);
+	XFS_IS_CORRUPT(mp, atomic_read(&xg->xg_active_ref) != 0);
+	kfree_rcu_mightsleep(xg);
+}
+
+int
+xfs_group_insert(
+	struct xfs_mount	*mp,
+	struct xfs_group	*xg,
+	uint32_t		index,
+	enum xfs_group_type	type)
+{
+	int			error;
+
+	xg->xg_mount = mp;
+	xg->xg_gno = index;
+	xg->xg_type = type;
+
+	/* Active ref owned by mount indicates group is online. */
+	atomic_set(&xg->xg_active_ref, 1);
+
+	error = xa_insert(&mp->m_groups[type].xa, index, xg, GFP_KERNEL);
+	if (error) {
+		WARN_ON_ONCE(error == -EBUSY);
+		return error;
+	}
+
+	return 0;
+}

fs/xfs/libxfs/xfs_group.h

@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2018 Red Hat, Inc.
+ */
+#ifndef __LIBXFS_GROUP_H
+#define __LIBXFS_GROUP_H 1
+
+struct xfs_group {
+	struct xfs_mount	*xg_mount;
+	uint32_t		xg_gno;
+	enum xfs_group_type	xg_type;
+	atomic_t		xg_ref;		/* passive reference count */
+	atomic_t		xg_active_ref;	/* active reference count */
+};
+
+struct xfs_group *xfs_group_get(struct xfs_mount *mp, uint32_t index,
+		enum xfs_group_type type);
+struct xfs_group *xfs_group_hold(struct xfs_group *xg);
+void xfs_group_put(struct xfs_group *xg);
+
+struct xfs_group *xfs_group_grab(struct xfs_mount *mp, uint32_t index,
+		enum xfs_group_type type);
+struct xfs_group *xfs_group_grab_next_mark(struct xfs_mount *mp,
+		struct xfs_group *xg, xa_mark_t mark, enum xfs_group_type type);
+void xfs_group_rele(struct xfs_group *xg);
+
+void xfs_group_free(struct xfs_mount *mp, uint32_t index,
+		enum xfs_group_type type, void (*uninit)(struct xfs_group *xg));
+int xfs_group_insert(struct xfs_mount *mp, struct xfs_group *xg,
+		uint32_t index, enum xfs_group_type);
+
+#define xfs_group_set_mark(_xg, _mark) \
+	xa_set_mark(&(_xg)->xg_mount->m_groups[(_xg)->xg_type].xa, \
+			(_xg)->xg_gno, (_mark))
+#define xfs_group_clear_mark(_xg, _mark) \
+	xa_clear_mark(&(_xg)->xg_mount->m_groups[(_xg)->xg_type].xa, \
+			(_xg)->xg_gno, (_mark))
+#define xfs_group_marked(_mp, _type, _mark) \
+	xa_marked(&(_mp)->m_groups[(_type)].xa, (_mark))
+
+#endif /* __LIBXFS_GROUP_H */

fs/xfs/libxfs/xfs_ialloc.c

@@ -142,7 +142,7 @@ xfs_inobt_complain_bad_rec(
 
 	xfs_warn(mp,
 		"%sbt record corruption in AG %d detected at %pS!",
-		cur->bc_ops->name, cur->bc_ag.pag->pag_agno, fa);
+		cur->bc_ops->name, pag_agno(cur->bc_ag.pag), fa);
 	xfs_warn(mp,
 "start inode 0x%x, count 0x%x, free 0x%x freemask 0x%llx, holemask 0x%x",
 		irec->ir_startino, irec->ir_count, irec->ir_freecount,
@@ -551,7 +551,7 @@ xfs_inobt_insert_sprec(
 	struct xfs_buf			*agbp,
 	struct xfs_inobt_rec_incore	*nrec)	/* in/out: new/merged rec. */
 {
-	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_mount		*mp = pag_mount(pag);
 	struct xfs_btree_cur		*cur;
 	int				error;
 	int				i;
@@ -645,7 +645,7 @@ xfs_finobt_insert_sprec(
 	struct xfs_buf			*agbp,
 	struct xfs_inobt_rec_incore	*nrec)	/* in/out: new rec. */
 {
-	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_mount		*mp = pag_mount(pag);
 	struct xfs_btree_cur		*cur;
 	int				error;
 	int				i;
@@ -880,7 +880,7 @@ sparse_alloc:
 	 * rather than a linear progression to prevent the next generation
 	 * number from being easily guessable.
 	 */
-	error = xfs_ialloc_inode_init(args.mp, tp, NULL, newlen, pag->pag_agno,
+	error = xfs_ialloc_inode_init(args.mp, tp, NULL, newlen, pag_agno(pag),
 			args.agbno, args.len, get_random_u32());
 
 	if (error)
@@ -1071,7 +1071,7 @@ xfs_dialloc_check_ino(
 	if (error)
 		return -EAGAIN;
 
-	error = xfs_imap_to_bp(pag->pag_mount, tp, &imap, &bp);
+	error = xfs_imap_to_bp(pag_mount(pag), tp, &imap, &bp);
 	if (error)
 		return -EAGAIN;
 
@@ -1122,7 +1122,7 @@ xfs_dialloc_ag_inobt(
 	/*
 	 * If in the same AG as the parent, try to get near the parent.
 	 */
-	if (pagno == pag->pag_agno) {
+	if (pagno == pag_agno(pag)) {
 		int		doneleft;	/* done, to the left */
 		int		doneright;	/* done, to the right */
 
@@ -1599,7 +1599,7 @@ xfs_dialloc_ag(
 	 * parent. If so, find the closest available inode to the parent. If
 	 * not, consider the agi hint or find the first free inode in the AG.
 	 */
-	if (pag->pag_agno == pagno)
+	if (pag_agno(pag) == pagno)
 		error = xfs_dialloc_ag_finobt_near(pagino, &cur, &rec);
 	else
 		error = xfs_dialloc_ag_finobt_newino(agi, cur, &rec);
@@ -2053,7 +2053,7 @@ xfs_difree_inobt(
 	struct xfs_icluster		*xic,
 	struct xfs_inobt_rec_incore	*orec)
 {
-	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_mount		*mp = pag_mount(pag);
 	struct xfs_agi			*agi = agbp->b_addr;
 	struct xfs_btree_cur		*cur;
 	struct xfs_inobt_rec_incore	rec;
@@ -2187,7 +2187,7 @@ xfs_difree_finobt(
 	xfs_agino_t			agino,
 	struct xfs_inobt_rec_incore	*ibtrec) /* inobt record */
 {
-	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_mount		*mp = pag_mount(pag);
 	struct xfs_btree_cur		*cur;
 	struct xfs_inobt_rec_incore	rec;
 	int				offset = agino - ibtrec->ir_startino;
@@ -2310,9 +2310,9 @@ xfs_difree(
 	/*
 	 * Break up inode number into its components.
 	 */
-	if (pag->pag_agno != XFS_INO_TO_AGNO(mp, inode)) {
-		xfs_warn(mp, "%s: agno != pag->pag_agno (%d != %d).",
-			__func__, XFS_INO_TO_AGNO(mp, inode), pag->pag_agno);
+	if (pag_agno(pag) != XFS_INO_TO_AGNO(mp, inode)) {
+		xfs_warn(mp, "%s: agno != pag_agno(pag) (%d != %d).",
+			__func__, XFS_INO_TO_AGNO(mp, inode), pag_agno(pag));
 		ASSERT(0);
 		return -EINVAL;
 	}
@@ -2373,7 +2373,7 @@ xfs_imap_lookup(
 	xfs_agblock_t		*offset_agbno,
 	int			flags)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	struct xfs_inobt_rec_incore rec;
 	struct xfs_btree_cur	*cur;
 	struct xfs_buf		*agbp;
@@ -2384,7 +2384,7 @@ xfs_imap_lookup(
 	if (error) {
 		xfs_alert(mp,
 			"%s: xfs_ialloc_read_agi() returned error %d, agno %d",
-			__func__, error, pag->pag_agno);
+			__func__, error, pag_agno(pag));
 		return error;
 	}
 
@@ -2434,7 +2434,7 @@ xfs_imap(
 	struct xfs_imap		*imap,	/* location map structure */
 	uint			flags)	/* flags for inode btree lookup */
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	xfs_agblock_t		agbno;	/* block number of inode in the alloc group */
 	xfs_agino_t		agino;	/* inode number within alloc group */
 	xfs_agblock_t		chunk_agbno;	/* first block in inode chunk */
@@ -2726,13 +2726,13 @@ xfs_read_agi(
 	xfs_buf_flags_t		flags,
 	struct xfs_buf		**agibpp)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	int			error;
 
 	trace_xfs_read_agi(pag);
 
 	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
-			XFS_AG_DADDR(mp, pag->pag_agno, XFS_AGI_DADDR(mp)),
+			XFS_AG_DADDR(mp, pag_agno(pag), XFS_AGI_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), flags, agibpp, &xfs_agi_buf_ops);
 	if (xfs_metadata_is_sick(error))
 		xfs_ag_mark_sick(pag, XFS_SICK_AG_AGI);
@@ -2780,7 +2780,7 @@ xfs_ialloc_read_agi(
 	 * we are in the middle of a forced shutdown.
 	 */
 	ASSERT(pag->pagi_freecount == be32_to_cpu(agi->agi_freecount) ||
-		xfs_is_shutdown(pag->pag_mount));
+		xfs_is_shutdown(pag_mount(pag)));
 	if (agibpp)
 		*agibpp = agibp;
 	else
@@ -3119,13 +3119,13 @@ xfs_ialloc_check_shrink(
 	int			has;
 	int			error;
 
-	if (!xfs_has_sparseinodes(pag->pag_mount))
+	if (!xfs_has_sparseinodes(pag_mount(pag)))
 		return 0;
 
 	cur = xfs_inobt_init_cursor(pag, tp, agibp);
 
 	/* Look up the inobt record that would correspond to the new EOFS. */
-	agino = XFS_AGB_TO_AGINO(pag->pag_mount, new_length);
+	agino = XFS_AGB_TO_AGINO(pag_mount(pag), new_length);
 	error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &has);
 	if (error || !has)
 		goto out;

fs/xfs/libxfs/xfs_ialloc_btree.c

@@ -248,7 +248,7 @@ xfs_inobt_init_ptr_from_cur(
 {
 	struct xfs_agi		*agi = cur->bc_ag.agbp->b_addr;
 
-	ASSERT(cur->bc_ag.pag->pag_agno == be32_to_cpu(agi->agi_seqno));
+	ASSERT(pag_agno(cur->bc_ag.pag) == be32_to_cpu(agi->agi_seqno));
 
 	ptr->s = agi->agi_root;
 }
@@ -260,7 +260,7 @@ xfs_finobt_init_ptr_from_cur(
 {
 	struct xfs_agi		*agi = cur->bc_ag.agbp->b_addr;
 
-	ASSERT(cur->bc_ag.pag->pag_agno == be32_to_cpu(agi->agi_seqno));
+	ASSERT(pag_agno(cur->bc_ag.pag) == be32_to_cpu(agi->agi_seqno));
 	ptr->s = agi->agi_free_root;
 }
 
@@ -478,7 +478,7 @@ xfs_inobt_init_cursor(
 	struct xfs_trans	*tp,
 	struct xfs_buf		*agbp)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	struct xfs_btree_cur	*cur;
 
 	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_inobt_ops,
@@ -504,7 +504,7 @@ xfs_finobt_init_cursor(
 	struct xfs_trans	*tp,
 	struct xfs_buf		*agbp)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	struct xfs_btree_cur	*cur;
 
 	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_finobt_ops,
@@ -715,7 +715,7 @@ static xfs_extlen_t
 xfs_inobt_max_size(
 	struct xfs_perag	*pag)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	xfs_agblock_t		agblocks = pag->block_count;
 
 	/* Bail out if we're uninitialized, which can happen in mkfs. */
@@ -727,7 +727,7 @@ xfs_inobt_max_size(
 	 * never be available for the kinds of things that would require btree
 	 * expansion.  We therefore can pretend the space isn't there.
 	 */
-	if (xfs_ag_contains_log(mp, pag->pag_agno))
+	if (xfs_ag_contains_log(mp, pag_agno(pag)))
 		agblocks -= mp->m_sb.sb_logblocks;
 
 	return xfs_btree_calc_size(M_IGEO(mp)->inobt_mnr,
@@ -791,10 +791,10 @@ xfs_finobt_calc_reserves(
 	xfs_extlen_t		tree_len = 0;
 	int			error;
 
-	if (!xfs_has_finobt(pag->pag_mount))
+	if (!xfs_has_finobt(pag_mount(pag)))
 		return 0;
 
-	if (xfs_has_inobtcounts(pag->pag_mount))
+	if (xfs_has_inobtcounts(pag_mount(pag)))
 		error = xfs_finobt_read_blocks(pag, tp, &tree_len);
 	else
 		error = xfs_finobt_count_blocks(pag, tp, &tree_len);

fs/xfs/libxfs/xfs_refcount.c

@@ -154,7 +154,7 @@ xfs_refcount_complain_bad_rec(
 
 	xfs_warn(mp,
  "Refcount BTree record corruption in AG %d detected at %pS!",
-				cur->bc_ag.pag->pag_agno, fa);
+				pag_agno(cur->bc_ag.pag), fa);
 	xfs_warn(mp,
 		"Start block 0x%x, block count 0x%x, references 0x%x",
 		irec->rc_startblock, irec->rc_blockcount, irec->rc_refcount);
@@ -1321,7 +1321,7 @@ xfs_refcount_continue_op(
 	ri->ri_startblock = xfs_agbno_to_fsb(pag, new_agbno);
 
 	ASSERT(xfs_verify_fsbext(mp, ri->ri_startblock, ri->ri_blockcount));
-	ASSERT(pag->pag_agno == XFS_FSB_TO_AGNO(mp, ri->ri_startblock));
+	ASSERT(pag_agno(pag) == XFS_FSB_TO_AGNO(mp, ri->ri_startblock));
 
 	return 0;
 }

fs/xfs/libxfs/xfs_refcount_btree.c

@@ -81,7 +81,7 @@ xfs_refcountbt_alloc_block(
 		*stat = 0;
 		return 0;
 	}
-	ASSERT(args.agno == cur->bc_ag.pag->pag_agno);
+	ASSERT(args.agno == pag_agno(cur->bc_ag.pag));
 	ASSERT(args.len == 1);
 
 	new->s = cpu_to_be32(args.agbno);
@@ -169,7 +169,7 @@ xfs_refcountbt_init_ptr_from_cur(
 {
 	struct xfs_agf		*agf = cur->bc_ag.agbp->b_addr;
 
-	ASSERT(cur->bc_ag.pag->pag_agno == be32_to_cpu(agf->agf_seqno));
+	ASSERT(pag_agno(cur->bc_ag.pag) == be32_to_cpu(agf->agf_seqno));
 
 	ptr->s = agf->agf_refcount_root;
 }
@@ -361,7 +361,7 @@ xfs_refcountbt_init_cursor(
 {
 	struct xfs_btree_cur	*cur;
 
-	ASSERT(pag->pag_agno < mp->m_sb.sb_agcount);
+	ASSERT(pag_agno(pag) < mp->m_sb.sb_agcount);
 
 	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_refcountbt_ops,
 			mp->m_refc_maxlevels, xfs_refcountbt_cur_cache);
@@ -514,7 +514,7 @@ xfs_refcountbt_calc_reserves(
 	 * never be available for the kinds of things that would require btree
 	 * expansion.  We therefore can pretend the space isn't there.
 	 */
-	if (xfs_ag_contains_log(mp, pag->pag_agno))
+	if (xfs_ag_contains_log(mp, pag_agno(pag)))
 		agblocks -= mp->m_sb.sb_logblocks;
 
 	*ask += xfs_refcountbt_max_size(mp, agblocks);

fs/xfs/libxfs/xfs_rmap.c

@@ -213,7 +213,7 @@ xfs_rmap_check_irec(
 	struct xfs_perag		*pag,
 	const struct xfs_rmap_irec	*irec)
 {
-	struct xfs_mount		*mp = pag->pag_mount;
+	struct xfs_mount		*mp = pag_mount(pag);
 	bool				is_inode;
 	bool				is_unwritten;
 	bool				is_bmbt;
@@ -288,7 +288,7 @@ xfs_rmap_complain_bad_rec(
 	else
 		xfs_warn(mp,
  "Reverse Mapping BTree record corruption in AG %d detected at %pS!",
-			cur->bc_ag.pag->pag_agno, fa);
+			pag_agno(cur->bc_ag.pag), fa);
 	xfs_warn(mp,
 		"Owner 0x%llx, flags 0x%x, start block 0x%x block count 0x%x",
 		irec->rm_owner, irec->rm_flags, irec->rm_startblock,

fs/xfs/libxfs/xfs_rmap_btree.c

@@ -227,7 +227,7 @@ xfs_rmapbt_init_ptr_from_cur(
 {
 	struct xfs_agf		*agf = cur->bc_ag.agbp->b_addr;
 
-	ASSERT(cur->bc_ag.pag->pag_agno == be32_to_cpu(agf->agf_seqno));
+	ASSERT(pag_agno(cur->bc_ag.pag) == be32_to_cpu(agf->agf_seqno));
 
 	ptr->s = agf->agf_rmap_root;
 }
@@ -647,9 +647,8 @@ xfs_rmapbt_mem_cursor(
 	struct xfbtree		*xfbt)
 {
 	struct xfs_btree_cur	*cur;
-	struct xfs_mount	*mp = pag->pag_mount;
 
-	cur = xfs_btree_alloc_cursor(mp, tp, &xfs_rmapbt_mem_ops,
+	cur = xfs_btree_alloc_cursor(pag_mount(pag), tp, &xfs_rmapbt_mem_ops,
 			xfs_rmapbt_maxlevels_ondisk(), xfs_rmapbt_cur_cache);
 	cur->bc_mem.xfbtree = xfbt;
 	cur->bc_nlevels = xfbt->nlevels;
@@ -863,7 +862,7 @@ xfs_rmapbt_calc_reserves(
 	 * never be available for the kinds of things that would require btree
 	 * expansion.  We therefore can pretend the space isn't there.
 	 */
-	if (xfs_ag_contains_log(mp, pag->pag_agno))
+	if (xfs_ag_contains_log(mp, pag_agno(pag)))
 		agblocks -= mp->m_sb.sb_logblocks;
 
 	/* Reserve 1% of the AG or enough for 1 block per record. */

fs/xfs/libxfs/xfs_sb.c

@@ -1120,7 +1120,7 @@ xfs_update_secondary_sbs(
 		struct xfs_buf		*bp;
 
 		error = xfs_buf_get(mp->m_ddev_targp,
-				 XFS_AG_DADDR(mp, pag->pag_agno, XFS_SB_DADDR),
+				 XFS_AG_DADDR(mp, pag_agno(pag), XFS_SB_DADDR),
 				 XFS_FSS_TO_BB(mp, 1), &bp);
 		/*
 		 * If we get an error reading or writing alternate superblocks,
@@ -1132,7 +1132,7 @@ xfs_update_secondary_sbs(
 		if (error) {
 			xfs_warn(mp,
 		"error allocating secondary superblock for ag %d",
-				pag->pag_agno);
+				pag_agno(pag));
 			if (!saved_error)
 				saved_error = error;
 			continue;
@@ -1153,7 +1153,7 @@ xfs_update_secondary_sbs(
 		if (error) {
 			xfs_warn(mp,
 		"write error %d updating a secondary superblock near ag %d",
-				error, pag->pag_agno);
+				error, pag_agno(pag));
 			if (!saved_error)
 				saved_error = error;
 			continue;

fs/xfs/libxfs/xfs_types.h

@@ -212,6 +212,14 @@ enum xbtree_recpacking {
 	XBTREE_RECPACKING_FULL,
 };
 
+enum xfs_group_type {
+	XG_TYPE_AG,
+	XG_TYPE_MAX,
+} __packed;
+
+#define XG_TYPE_STRINGS \
+	{ XG_TYPE_AG,	"ag" }
+
 /*
  * Type verifier functions
  */

fs/xfs/scrub/agheader_repair.c

@@ -208,7 +208,7 @@ xrep_agf_init_header(
 	memset(agf, 0, BBTOB(agf_bp->b_length));
 	agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
 	agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
-	agf->agf_seqno = cpu_to_be32(pag->pag_agno);
+	agf->agf_seqno = cpu_to_be32(pag_agno(pag));
 	agf->agf_length = cpu_to_be32(pag->block_count);
 	agf->agf_flfirst = old_agf->agf_flfirst;
 	agf->agf_fllast = old_agf->agf_fllast;
@@ -384,7 +384,7 @@ xrep_agf(
 	 * was corrupt after xfs_alloc_read_agf failed with -EFSCORRUPTED.
 	 */
 	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
-			XFS_AG_DADDR(mp, sc->sa.pag->pag_agno,
+			XFS_AG_DADDR(mp, pag_agno(sc->sa.pag),
 						XFS_AGF_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), 0, &agf_bp, NULL);
 	if (error)
@@ -687,7 +687,7 @@ xrep_agfl_init_header(
 	agfl = XFS_BUF_TO_AGFL(agfl_bp);
 	memset(agfl, 0xFF, BBTOB(agfl_bp->b_length));
 	agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
-	agfl->agfl_seqno = cpu_to_be32(sc->sa.pag->pag_agno);
+	agfl->agfl_seqno = cpu_to_be32(pag_agno(sc->sa.pag));
 	uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
 
 	/*
@@ -741,7 +741,7 @@ xrep_agfl(
 	 * was corrupt after xfs_alloc_read_agfl failed with -EFSCORRUPTED.
 	 */
 	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
-			XFS_AG_DADDR(mp, sc->sa.pag->pag_agno,
+			XFS_AG_DADDR(mp, pag_agno(sc->sa.pag),
 						XFS_AGFL_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), 0, &agfl_bp, NULL);
 	if (error)
@@ -897,7 +897,7 @@ xrep_agi_init_header(
 	memset(agi, 0, BBTOB(agi_bp->b_length));
 	agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
 	agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
-	agi->agi_seqno = cpu_to_be32(pag->pag_agno);
+	agi->agi_seqno = cpu_to_be32(pag_agno(pag));
 	agi->agi_length = cpu_to_be32(pag->block_count);
 	agi->agi_newino = cpu_to_be32(NULLAGINO);
 	agi->agi_dirino = cpu_to_be32(NULLAGINO);
@@ -1112,9 +1112,9 @@ xrep_iunlink_igrab(
 	struct xfs_perag	*pag,
 	struct xfs_inode	*ip)
 {
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 
-	if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno)
+	if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag_agno(pag))
 		return false;
 
 	if (!xfs_inode_on_unlinked_list(ip))
@@ -1138,7 +1138,7 @@ xrep_iunlink_visit(
 	unsigned int		bucket;
 	int			error;
 
-	ASSERT(XFS_INO_TO_AGNO(mp, ip->i_ino) == ragi->sc->sa.pag->pag_agno);
+	ASSERT(XFS_INO_TO_AGNO(mp, ip->i_ino) == pag_agno(ragi->sc->sa.pag));
 	ASSERT(xfs_inode_on_unlinked_list(ip));
 
 	agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
@@ -1169,7 +1169,7 @@ xrep_iunlink_mark_incore(
 	struct xrep_agi		*ragi)
 {
 	struct xfs_perag	*pag = ragi->sc->sa.pag;
-	struct xfs_mount	*mp = pag->pag_mount;
+	struct xfs_mount	*mp = pag_mount(pag);
 	uint32_t		first_index = 0;
 	bool			done = false;
 	unsigned int		nr_found = 0;
@@ -1209,7 +1209,7 @@ xrep_iunlink_mark_incore(
 			 * us to see this inode, so another lookup from the
 			 * same index will not find it again.
 			 */
-			if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag->pag_agno)
+			if (XFS_INO_TO_AGNO(mp, ip->i_ino) != pag_agno(pag))
 				continue;
 			first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
 			if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
@@ -1761,7 +1761,7 @@ xrep_agi(
 	 * was corrupt after xfs_ialloc_read_agi failed with -EFSCORRUPTED.
 	 */
 	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
-			XFS_AG_DADDR(mp, sc->sa.pag->pag_agno,
+			XFS_AG_DADDR(mp, pag_agno(sc->sa.pag),
 						XFS_AGI_DADDR(mp)),
 			XFS_FSS_TO_BB(mp, 1), 0, &ragi->agi_bp, NULL);
 	if (error)

fs/xfs/scrub/alloc_repair.c

@@ -543,7 +543,7 @@ xrep_abt_dispose_one(
 
 	/* Add a deferred rmap for each extent we used. */
 	if (resv->used > 0)
-		xfs_rmap_alloc_extent(sc->tp, pag->pag_agno, resv->agbno,
+		xfs_rmap_alloc_extent(sc->tp, pag_agno(pag), resv->agbno,
 				resv->used, XFS_RMAP_OWN_AG);
 
 	/*