Merge tag 'xfs-perag-conv-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs into xfs-5.14-merge2

xfs: initial agnumber -> perag conversions for shrink

If we want to use active references to the perag to be able to gate
shrink removing AGs and hence perags safely, we've got a fair bit of
work to do actually use perags in all the places we need to.

There's a lot of code that iterates ag numbers and then
looks up perags from that, often multiple times for the same perag
in the one operation. If we want to use reference counted perags for
access control, then we need to convert all these uses to perag
iterators, not agno iterators.

[Patches 1-4]

The first step of this is consolidating all the perag management -
init, free, get, put, etc into a common location. THis is spread all
over the place right now, so move it all into libxfs/xfs_ag.[ch].
This does expose kernel only bits of the perag to libxfs and hence
userspace, so the structures and code is rearranged to minimise the
number of ifdefs that need to be added to the userspace codebase.
The perag iterator in xfs_icache.c is promoted to a first class API
and expanded to the needs of the code as required.

[Patches 5-10]

These are the first basic perag iterator conversions and changes to
pass the perag down the stack from those iterators where
appropriate. A lot of this is obvious, simple changes, though in
some places we stop passing the perag down the stack because the
code enters into an as yet unconverted subsystem that still uses raw
AGs.

[Patches 11-16]

These replace the agno passed in the btree cursor for per-ag btree
operations with a perag that is passed to the cursor init function.
The cursor takes it's own reference to the perag, and the reference
is dropped when the cursor is deleted. Hence we get reference
coverage for the entire time the cursor is active, even if the code
that initialised the cursor drops it's reference before the cursor
or any of it's children (duplicates) have been deleted.

The first patch adds the perag infrastructure for the cursor, the
next four patches convert a btree cursor at a time, and the last
removes the agno from the cursor once it is unused.

[Patches 17-21]

These patches are a demonstration of the simplifications and
cleanups that come from plumbing the perag through interfaces that
select and then operate on a specific AG. In this case the inode
allocation algorithm does up to three walks across all AGs before it
either allocates an inode or fails. Two of these walks are purely
just to select the AG, and even then it doesn't guarantee inode
allocation success so there's a third walk if the selected AG
allocation fails.

These patches collapse the selection and allocation into a single
loop, simplifies the error handling because xfs_dir_ialloc() always
returns ENOSPC if no AG was selected for inode allocation or we fail
to allocate an inode in any AG, gets rid of xfs_dir_ialloc()
wrapper, converts inode allocation to run entirely from a single
perag instance, and then factors xfs_dialloc() into a much, much
simpler loop which is easy to understand.

Hence we end up with the same inode allocation logic, but it only
needs two complete iterations at worst, makes AG selection and
allocation atomic w.r.t. shrink and chops out out over 100 lines of
code from this hot code path.

[Patch 22]

Converts the unlink path to pass perags through it.

There's more conversion work to be done, but this patchset gets
through a large chunk of it in one hit. Most of the iterators are
converted, so once this is solidified we can move on to converting
these to active references for being able to free perags while the
fs is still active.

* tag 'xfs-perag-conv-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (23 commits)
  xfs: remove xfs_perag_t
  xfs: use perag through unlink processing
  xfs: clean up and simplify xfs_dialloc()
  xfs: inode allocation can use a single perag instance
  xfs: get rid of xfs_dir_ialloc()
  xfs: collapse AG selection for inode allocation
  xfs: simplify xfs_dialloc_select_ag() return values
  xfs: remove agno from btree cursor
  xfs: use perag for ialloc btree cursors
  xfs: convert allocbt cursors to use perags
  xfs: convert refcount btree cursor to use perags
  xfs: convert rmap btree cursor to using a perag
  xfs: add a perag to the btree cursor
  xfs: pass perags around in fsmap data dev functions
  xfs: push perags through the ag reservation callouts
  xfs: pass perags through to the busy extent code
  xfs: convert secondary superblock walk to use perags
  xfs: convert xfs_iwalk to use perag references
  xfs: convert raw ag walks to use for_each_perag
  xfs: make for_each_perag... a first class citizen
  ...

1 files changed, 284 insertions, 324 deletions

diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
index eefdb518fe64..2ed6de6faf8a 100644
--- a/fs/xfs/libxfs/xfs_ialloc.c
+++ b/fs/xfs/libxfs/xfs_ialloc.c
@@ -10,7 +10,6 @@
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_bit.h"
-#include "xfs_sb.h"
 #include "xfs_mount.h"
 #include "xfs_inode.h"
 #include "xfs_btree.h"
@@ -27,6 +26,7 @@
 #include "xfs_trace.h"
 #include "xfs_log.h"
 #include "xfs_rmap.h"
+#include "xfs_ag.h"
 
 /*
  * Lookup a record by ino in the btree given by cur.
@@ -105,7 +105,7 @@ xfs_inobt_get_rec(
 	int				*stat)
 {
 	struct xfs_mount		*mp = cur->bc_mp;
-	xfs_agnumber_t			agno = cur->bc_ag.agno;
+	xfs_agnumber_t			agno = cur->bc_ag.pag->pag_agno;
 	union xfs_btree_rec		*rec;
 	int				error;
 	uint64_t			realfree;
@@ -172,18 +172,17 @@ xfs_inobt_insert(
 	struct xfs_mount	*mp,
 	struct xfs_trans	*tp,
 	struct xfs_buf		*agbp,
+	struct xfs_perag	*pag,
 	xfs_agino_t		newino,
 	xfs_agino_t		newlen,
 	xfs_btnum_t		btnum)
 {
 	struct xfs_btree_cur	*cur;
-	struct xfs_agi		*agi = agbp->b_addr;
-	xfs_agnumber_t		agno = be32_to_cpu(agi->agi_seqno);
 	xfs_agino_t		thisino;
 	int			i;
 	int			error;
 
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, btnum);
+	cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, btnum);
 
 	for (thisino = newino;
 	     thisino < newino + newlen;
@@ -520,18 +519,17 @@ xfs_inobt_insert_sprec(
 	struct xfs_mount		*mp,
 	struct xfs_trans		*tp,
 	struct xfs_buf			*agbp,
+	struct xfs_perag		*pag,
 	int				btnum,
 	struct xfs_inobt_rec_incore	*nrec,	/* in/out: new/merged rec. */
 	bool				merge)	/* merge or replace */
 {
 	struct xfs_btree_cur		*cur;
-	struct xfs_agi			*agi = agbp->b_addr;
-	xfs_agnumber_t			agno = be32_to_cpu(agi->agi_seqno);
 	int				error;
 	int				i;
 	struct xfs_inobt_rec_incore	rec;
 
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, btnum);
+	cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, btnum);
 
 	/* the new record is pre-aligned so we know where to look */
 	error = xfs_inobt_lookup(cur, nrec->ir_startino, XFS_LOOKUP_EQ, &i);
@@ -578,14 +576,14 @@ xfs_inobt_insert_sprec(
 			goto error;
 		}
 
-		trace_xfs_irec_merge_pre(mp, agno, rec.ir_startino,
+		trace_xfs_irec_merge_pre(mp, pag->pag_agno, rec.ir_startino,
 					 rec.ir_holemask, nrec->ir_startino,
 					 nrec->ir_holemask);
 
 		/* merge to nrec to output the updated record */
 		__xfs_inobt_rec_merge(nrec, &rec);
 
-		trace_xfs_irec_merge_post(mp, agno, nrec->ir_startino,
+		trace_xfs_irec_merge_post(mp, pag->pag_agno, nrec->ir_startino,
 					  nrec->ir_holemask);
 
 		error = xfs_inobt_rec_check_count(mp, nrec);
@@ -606,28 +604,28 @@ error:
 }
 
 /*
- * Allocate new inodes in the allocation group specified by agbp.
- * Returns 0 if inodes were allocated in this AG; 1 if there was no space
- * in this AG; or the usual negative error code.
+ * Allocate new inodes in the allocation group specified by agbp.  Returns 0 if
+ * inodes were allocated in this AG; -EAGAIN if there was no space in this AG so
+ * the caller knows it can try another AG, a hard -ENOSPC when over the maximum
+ * inode count threshold, or the usual negative error code for other errors.
  */
 STATIC int
 xfs_ialloc_ag_alloc(
 	struct xfs_trans	*tp,
-	struct xfs_buf		*agbp)
+	struct xfs_buf		*agbp,
+	struct xfs_perag	*pag)
 {
 	struct xfs_agi		*agi;
 	struct xfs_alloc_arg	args;
-	xfs_agnumber_t		agno;
 	int			error;
 	xfs_agino_t		newino;		/* new first inode's number */
 	xfs_agino_t		newlen;		/* new number of inodes */
 	int			isaligned = 0;	/* inode allocation at stripe */
 						/* unit boundary */
 	/* init. to full chunk */
-	uint16_t		allocmask = (uint16_t) -1;
 	struct xfs_inobt_rec_incore rec;
-	struct xfs_perag	*pag;
 	struct xfs_ino_geometry	*igeo = M_IGEO(tp->t_mountp);
+	uint16_t		allocmask = (uint16_t) -1;
 	int			do_sparse = 0;
 
 	memset(&args, 0, sizeof(args));
@@ -660,14 +658,13 @@ xfs_ialloc_ag_alloc(
 	 */
 	agi = agbp->b_addr;
 	newino = be32_to_cpu(agi->agi_newino);
-	agno = be32_to_cpu(agi->agi_seqno);
 	args.agbno = XFS_AGINO_TO_AGBNO(args.mp, newino) +
 		     igeo->ialloc_blks;
 	if (do_sparse)
 		goto sparse_alloc;
 	if (likely(newino != NULLAGINO &&
 		  (args.agbno < be32_to_cpu(agi->agi_length)))) {
-		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
+		args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
 		args.type = XFS_ALLOCTYPE_THIS_BNO;
 		args.prod = 1;
 
@@ -727,7 +724,7 @@ xfs_ialloc_ag_alloc(
 		 * For now, just allocate blocks up front.
 		 */
 		args.agbno = be32_to_cpu(agi->agi_root);
-		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
+		args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
 		/*
 		 * Allocate a fixed-size extent of inodes.
 		 */
@@ -748,7 +745,7 @@ xfs_ialloc_ag_alloc(
 	if (isaligned && args.fsbno == NULLFSBLOCK) {
 		args.type = XFS_ALLOCTYPE_NEAR_BNO;
 		args.agbno = be32_to_cpu(agi->agi_root);
-		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
+		args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
 		args.alignment = igeo->cluster_align;
 		if ((error = xfs_alloc_vextent(&args)))
 			return error;
@@ -764,7 +761,7 @@ xfs_ialloc_ag_alloc(
 sparse_alloc:
 		args.type = XFS_ALLOCTYPE_NEAR_BNO;
 		args.agbno = be32_to_cpu(agi->agi_root);
-		args.fsbno = XFS_AGB_TO_FSB(args.mp, agno, args.agbno);
+		args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
 		args.alignment = args.mp->m_sb.sb_spino_align;
 		args.prod = 1;
 
@@ -796,7 +793,7 @@ sparse_alloc:
 	}
 
 	if (args.fsbno == NULLFSBLOCK)
-		return 1;
+		return -EAGAIN;
 
 	ASSERT(args.len == args.minlen);
 
@@ -809,7 +806,7 @@ 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, agno,
+	error = xfs_ialloc_inode_init(args.mp, tp, NULL, newlen, pag->pag_agno,
 			args.agbno, args.len, prandom_u32());
 
 	if (error)
@@ -836,12 +833,12 @@ sparse_alloc:
 		 * if necessary. If a merge does occur, rec is updated to the
 		 * merged record.
 		 */
-		error = xfs_inobt_insert_sprec(args.mp, tp, agbp, XFS_BTNUM_INO,
-					       &rec, true);
+		error = xfs_inobt_insert_sprec(args.mp, tp, agbp, pag,
+				XFS_BTNUM_INO, &rec, true);
 		if (error == -EFSCORRUPTED) {
 			xfs_alert(args.mp,
 	"invalid sparse inode record: ino 0x%llx holemask 0x%x count %u",
-				  XFS_AGINO_TO_INO(args.mp, agno,
+				  XFS_AGINO_TO_INO(args.mp, pag->pag_agno,
 						   rec.ir_startino),
 				  rec.ir_holemask, rec.ir_count);
 			xfs_force_shutdown(args.mp, SHUTDOWN_CORRUPT_INCORE);
@@ -861,21 +858,20 @@ sparse_alloc:
 		 * existing record with this one.
 		 */
 		if (xfs_sb_version_hasfinobt(&args.mp->m_sb)) {
-			error = xfs_inobt_insert_sprec(args.mp, tp, agbp,
-						       XFS_BTNUM_FINO, &rec,
-						       false);
+			error = xfs_inobt_insert_sprec(args.mp, tp, agbp, pag,
+				       XFS_BTNUM_FINO, &rec, false);
 			if (error)
 				return error;
 		}
 	} else {
 		/* full chunk - insert new records to both btrees */
-		error = xfs_inobt_insert(args.mp, tp, agbp, newino, newlen,
+		error = xfs_inobt_insert(args.mp, tp, agbp, pag, newino, newlen,
 					 XFS_BTNUM_INO);
 		if (error)
 			return error;
 
 		if (xfs_sb_version_hasfinobt(&args.mp->m_sb)) {
-			error = xfs_inobt_insert(args.mp, tp, agbp, newino,
+			error = xfs_inobt_insert(args.mp, tp, agbp, pag, newino,
 						 newlen, XFS_BTNUM_FINO);
 			if (error)
 				return error;
@@ -887,7 +883,6 @@ sparse_alloc:
 	 */
 	be32_add_cpu(&agi->agi_count, newlen);
 	be32_add_cpu(&agi->agi_freecount, newlen);
-	pag = agbp->b_pag;
 	pag->pagi_freecount += newlen;
 	pag->pagi_count += newlen;
 	agi->agi_newino = cpu_to_be32(newino);
@@ -905,139 +900,6 @@ sparse_alloc:
 	return 0;
 }
 
-STATIC xfs_agnumber_t
-xfs_ialloc_next_ag(
-	xfs_mount_t	*mp)
-{
-	xfs_agnumber_t	agno;
-
-	spin_lock(&mp->m_agirotor_lock);
-	agno = mp->m_agirotor;
-	if (++mp->m_agirotor >= mp->m_maxagi)
-		mp->m_agirotor = 0;
-	spin_unlock(&mp->m_agirotor_lock);
-
-	return agno;
-}
-
-/*
- * Select an allocation group to look for a free inode in, based on the parent
- * inode and the mode.  Return the allocation group buffer.
- */
-STATIC xfs_agnumber_t
-xfs_ialloc_ag_select(
-	xfs_trans_t	*tp,		/* transaction pointer */
-	xfs_ino_t	parent,		/* parent directory inode number */
-	umode_t		mode)		/* bits set to indicate file type */
-{
-	xfs_agnumber_t	agcount;	/* number of ag's in the filesystem */
-	xfs_agnumber_t	agno;		/* current ag number */
-	int		flags;		/* alloc buffer locking flags */
-	xfs_extlen_t	ineed;		/* blocks needed for inode allocation */
-	xfs_extlen_t	longest = 0;	/* longest extent available */
-	xfs_mount_t	*mp;		/* mount point structure */
-	int		needspace;	/* file mode implies space allocated */
-	xfs_perag_t	*pag;		/* per allocation group data */
-	xfs_agnumber_t	pagno;		/* parent (starting) ag number */
-	int		error;
-
-	/*
-	 * Files of these types need at least one block if length > 0
-	 * (and they won't fit in the inode, but that's hard to figure out).
-	 */
-	needspace = S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode);
-	mp = tp->t_mountp;
-	agcount = mp->m_maxagi;
-	if (S_ISDIR(mode))
-		pagno = xfs_ialloc_next_ag(mp);
-	else {
-		pagno = XFS_INO_TO_AGNO(mp, parent);
-		if (pagno >= agcount)
-			pagno = 0;
-	}
-
-	ASSERT(pagno < agcount);
-
-	/*
-	 * Loop through allocation groups, looking for one with a little
-	 * free space in it.  Note we don't look for free inodes, exactly.
-	 * Instead, we include whether there is a need to allocate inodes
-	 * to mean that blocks must be allocated for them,
-	 * if none are currently free.
-	 */
-	agno = pagno;
-	flags = XFS_ALLOC_FLAG_TRYLOCK;
-	for (;;) {
-		pag = xfs_perag_get(mp, agno);
-		if (!pag->pagi_inodeok) {
-			xfs_ialloc_next_ag(mp);
-			goto nextag;
-		}
-
-		if (!pag->pagi_init) {
-			error = xfs_ialloc_pagi_init(mp, tp, agno);
-			if (error)
-				goto nextag;
-		}
-
-		if (pag->pagi_freecount) {
-			xfs_perag_put(pag);
-			return agno;
-		}
-
-		if (!pag->pagf_init) {
-			error = xfs_alloc_pagf_init(mp, tp, agno, flags);
-			if (error)
-				goto nextag;
-		}
-
-		/*
-		 * Check that there is enough free space for the file plus a
-		 * chunk of inodes if we need to allocate some. If this is the
-		 * first pass across the AGs, take into account the potential
-		 * space needed for alignment of inode chunks when checking the
-		 * longest contiguous free space in the AG - this prevents us
-		 * from getting ENOSPC because we have free space larger than
-		 * ialloc_blks but alignment constraints prevent us from using
-		 * it.
-		 *
-		 * If we can't find an AG with space for full alignment slack to
-		 * be taken into account, we must be near ENOSPC in all AGs.
-		 * Hence we don't include alignment for the second pass and so
-		 * if we fail allocation due to alignment issues then it is most
-		 * likely a real ENOSPC condition.
-		 */
-		ineed = M_IGEO(mp)->ialloc_min_blks;
-		if (flags && ineed > 1)
-			ineed += M_IGEO(mp)->cluster_align;
-		longest = pag->pagf_longest;
-		if (!longest)
-			longest = pag->pagf_flcount > 0;
-
-		if (pag->pagf_freeblks >= needspace + ineed &&
-		    longest >= ineed) {
-			xfs_perag_put(pag);
-			return agno;
-		}
-nextag:
-		xfs_perag_put(pag);
-		/*
-		 * No point in iterating over the rest, if we're shutting
-		 * down.
-		 */
-		if (XFS_FORCED_SHUTDOWN(mp))
-			return NULLAGNUMBER;
-		agno++;
-		if (agno >= agcount)
-			agno = 0;
-		if (agno == pagno) {
-			if (flags == 0)
-				return NULLAGNUMBER;
-			flags = 0;
-		}
-	}
-}
-
 /*
  * Try to retrieve the next record to the left/right from the current one.
  */
@@ -1123,15 +985,14 @@ STATIC int
 xfs_dialloc_ag_inobt(
 	struct xfs_trans	*tp,
 	struct xfs_buf		*agbp,
+	struct xfs_perag	*pag,
 	xfs_ino_t		parent,
 	xfs_ino_t		*inop)
 {
 	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_agi		*agi = agbp->b_addr;
-	xfs_agnumber_t		agno = be32_to_cpu(agi->agi_seqno);
 	xfs_agnumber_t		pagno = XFS_INO_TO_AGNO(mp, parent);
 	xfs_agino_t		pagino = XFS_INO_TO_AGINO(mp, parent);
-	struct xfs_perag	*pag = agbp->b_pag;
 	struct xfs_btree_cur	*cur, *tcur;
 	struct xfs_inobt_rec_incore rec, trec;
 	xfs_ino_t		ino;
@@ -1145,7 +1006,7 @@ xfs_dialloc_ag_inobt(
 	ASSERT(pag->pagi_freecount > 0);
 
  restart_pagno:
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO);
+	cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
 	/*
 	 * If pagino is 0 (this is the root inode allocation) use newino.
 	 * This must work because we've just allocated some.
@@ -1160,7 +1021,7 @@ xfs_dialloc_ag_inobt(
 	/*
 	 * If in the same AG as the parent, try to get near the parent.
 	 */
-	if (pagno == agno) {
+	if (pagno == pag->pag_agno) {
 		int		doneleft;	/* done, to the left */
 		int		doneright;	/* done, to the right */
 
@@ -1363,7 +1224,7 @@ alloc_inode:
 	ASSERT(offset < XFS_INODES_PER_CHUNK);
 	ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
 				   XFS_INODES_PER_CHUNK) == 0);
-	ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino + offset);
+	ino = XFS_AGINO_TO_INO(mp, pag->pag_agno, rec.ir_startino + offset);
 	rec.ir_free &= ~XFS_INOBT_MASK(offset);
 	rec.ir_freecount--;
 	error = xfs_inobt_update(cur, &rec);
@@ -1568,16 +1429,16 @@ xfs_dialloc_ag_update_inobt(
  * The caller selected an AG for us, and made sure that free inodes are
  * available.
  */
-int
+static int
 xfs_dialloc_ag(
 	struct xfs_trans	*tp,
 	struct xfs_buf		*agbp,
+	struct xfs_perag	*pag,
 	xfs_ino_t		parent,
 	xfs_ino_t		*inop)
 {
 	struct xfs_mount		*mp = tp->t_mountp;
 	struct xfs_agi			*agi = agbp->b_addr;
-	xfs_agnumber_t			agno = be32_to_cpu(agi->agi_seqno);
 	xfs_agnumber_t			pagno = XFS_INO_TO_AGNO(mp, parent);
 	xfs_agino_t			pagino = XFS_INO_TO_AGINO(mp, parent);
 	struct xfs_btree_cur		*cur;	/* finobt cursor */
@@ -1589,7 +1450,7 @@ xfs_dialloc_ag(
 	int				i;
 
 	if (!xfs_sb_version_hasfinobt(&mp->m_sb))
-		return xfs_dialloc_ag_inobt(tp, agbp, parent, inop);
+		return xfs_dialloc_ag_inobt(tp, agbp, pag, parent, inop);
 
 	/*
 	 * If pagino is 0 (this is the root inode allocation) use newino.
@@ -1598,7 +1459,7 @@ xfs_dialloc_ag(
 	if (!pagino)
 		pagino = be32_to_cpu(agi->agi_newino);
 
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_FINO);
+	cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_FINO);
 
 	error = xfs_check_agi_freecount(cur, agi);
 	if (error)
@@ -1609,7 +1470,7 @@ 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 (agno == pagno)
+	if (pag->pag_agno == pagno)
 		error = xfs_dialloc_ag_finobt_near(pagino, &cur, &rec);
 	else
 		error = xfs_dialloc_ag_finobt_newino(agi, cur, &rec);
@@ -1621,7 +1482,7 @@ xfs_dialloc_ag(
 	ASSERT(offset < XFS_INODES_PER_CHUNK);
 	ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
 				   XFS_INODES_PER_CHUNK) == 0);
-	ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino + offset);
+	ino = XFS_AGINO_TO_INO(mp, pag->pag_agno, rec.ir_startino + offset);
 
 	/*
 	 * Modify or remove the finobt record.
@@ -1641,7 +1502,7 @@ xfs_dialloc_ag(
 	 * the original freecount. If all is well, make the equivalent update to
 	 * the inobt using the finobt record and offset information.
 	 */
-	icur = xfs_inobt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO);
+	icur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
 
 	error = xfs_check_agi_freecount(icur, agi);
 	if (error)
@@ -1657,7 +1518,7 @@ xfs_dialloc_ag(
 	 */
 	be32_add_cpu(&agi->agi_freecount, -1);
 	xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
-	agbp->b_pag->pagi_freecount--;
+	pag->pagi_freecount--;
 
 	xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -1);
 
@@ -1708,54 +1569,195 @@ xfs_dialloc_roll(
 	/* Re-attach the quota info that we detached from prev trx. */
 	tp->t_dqinfo = dqinfo;
 
+	/*
+	 * Join the buffer even on commit error so that the buffer is released
+	 * when the caller cancels the transaction and doesn't have to handle
+	 * this error case specially.
+	 */
+	xfs_trans_bjoin(tp, agibp);
 	*tpp = tp;
+	return error;
+}
+
+static xfs_agnumber_t
+xfs_ialloc_next_ag(
+	xfs_mount_t	*mp)
+{
+	xfs_agnumber_t	agno;
+
+	spin_lock(&mp->m_agirotor_lock);
+	agno = mp->m_agirotor;
+	if (++mp->m_agirotor >= mp->m_maxagi)
+		mp->m_agirotor = 0;
+	spin_unlock(&mp->m_agirotor_lock);
+
+	return agno;
+}
+
+static bool
+xfs_dialloc_good_ag(
+	struct xfs_trans	*tp,
+	struct xfs_perag	*pag,
+	umode_t			mode,
+	int			flags,
+	bool			ok_alloc)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	xfs_extlen_t		ineed;
+	xfs_extlen_t		longest = 0;
+	int			needspace;
+	int			error;
+
+	if (!pag->pagi_inodeok)
+		return false;
+
+	if (!pag->pagi_init) {
+		error = xfs_ialloc_pagi_init(mp, tp, pag->pag_agno);
+		if (error)
+			return false;
+	}
+
+	if (pag->pagi_freecount)
+		return true;
+	if (!ok_alloc)
+		return false;
+
+	if (!pag->pagf_init) {
+		error = xfs_alloc_pagf_init(mp, tp, pag->pag_agno, flags);
+		if (error)
+			return false;
+	}
+
+	/*
+	 * Check that there is enough free space for the file plus a chunk of
+	 * inodes if we need to allocate some. If this is the first pass across
+	 * the AGs, take into account the potential space needed for alignment
+	 * of inode chunks when checking the longest contiguous free space in
+	 * the AG - this prevents us from getting ENOSPC because we have free
+	 * space larger than ialloc_blks but alignment constraints prevent us
+	 * from using it.
+	 *
+	 * If we can't find an AG with space for full alignment slack to be
+	 * taken into account, we must be near ENOSPC in all AGs.  Hence we
+	 * don't include alignment for the second pass and so if we fail
+	 * allocation due to alignment issues then it is most likely a real
+	 * ENOSPC condition.
+	 *
+	 * XXX(dgc): this calculation is now bogus thanks to the per-ag
+	 * reservations that xfs_alloc_fix_freelist() now does via
+	 * xfs_alloc_space_available(). When the AG fills up, pagf_freeblks will
+	 * be more than large enough for the check below to succeed, but
+	 * xfs_alloc_space_available() will fail because of the non-zero
+	 * metadata reservation and hence we won't actually be able to allocate
+	 * more inodes in this AG. We do soooo much unnecessary work near ENOSPC
+	 * because of this.
+	 */
+	ineed = M_IGEO(mp)->ialloc_min_blks;
+	if (flags && ineed > 1)
+		ineed += M_IGEO(mp)->cluster_align;
+	longest = pag->pagf_longest;
+	if (!longest)
+		longest = pag->pagf_flcount > 0;
+	needspace = S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode);
+
+	if (pag->pagf_freeblks < needspace + ineed || longest < ineed)
+		return false;
+	return true;
+}
+
+static int
+xfs_dialloc_try_ag(
+	struct xfs_trans	**tpp,
+	struct xfs_perag	*pag,
+	xfs_ino_t		parent,
+	xfs_ino_t		*new_ino,
+	bool			ok_alloc)
+{
+	struct xfs_buf		*agbp;
+	xfs_ino_t		ino;
+	int			error;
+
+	/*
+	 * Then read in the AGI buffer and recheck with the AGI buffer
+	 * lock held.
+	 */
+	error = xfs_ialloc_read_agi(pag->pag_mount, *tpp, pag->pag_agno, &agbp);
 	if (error)
 		return error;
-	xfs_trans_bjoin(tp, agibp);
-	return 0;
+
+	if (!pag->pagi_freecount) {
+		if (!ok_alloc) {
+			error = -EAGAIN;
+			goto out_release;
+		}
+
+		error = xfs_ialloc_ag_alloc(*tpp, agbp, pag);
+		if (error < 0)
+			goto out_release;
+
+		/*
+		 * We successfully allocated space for an inode cluster in this
+		 * AG.  Roll the transaction so that we can allocate one of the
+		 * new inodes.
+		 */
+		ASSERT(pag->pagi_freecount > 0);
+		error = xfs_dialloc_roll(tpp, agbp);
+		if (error)
+			goto out_release;
+	}
+
+	/* Allocate an inode in the found AG */
+	error = xfs_dialloc_ag(*tpp, agbp, pag, parent, &ino);
+	if (!error)
+		*new_ino = ino;
+	return error;
+
+out_release:
+	xfs_trans_brelse(*tpp, agbp);
+	return error;
 }
 
 /*
- * Select and prepare an AG for inode allocation.
+ * Allocate an on-disk inode.
  *
  * Mode is used to tell whether the new inode is a directory and hence where to
- * locate it.
- *
- * This function will ensure that the selected AG has free inodes available to
- * allocate from. The selected AGI will be returned locked to the caller, and it
- * will allocate more free inodes if required. If no free inodes are found or
- * can be allocated, no AGI will be returned.
+ * locate it. The on-disk inode that is allocated will be returned in @new_ino
+ * on success, otherwise an error will be set to indicate the failure (e.g.
+ * -ENOSPC).
  */
 int
-xfs_dialloc_select_ag(
+xfs_dialloc(
 	struct xfs_trans	**tpp,
 	xfs_ino_t		parent,
 	umode_t			mode,
-	struct xfs_buf		**IO_agbp)
+	xfs_ino_t		*new_ino)
 {
 	struct xfs_mount	*mp = (*tpp)->t_mountp;
-	struct xfs_buf		*agbp;
 	xfs_agnumber_t		agno;
-	int			error;
-	bool			noroom = false;
+	int			error = 0;
 	xfs_agnumber_t		start_agno;
 	struct xfs_perag	*pag;
 	struct xfs_ino_geometry	*igeo = M_IGEO(mp);
-	bool			okalloc = true;
-
-	*IO_agbp = NULL;
+	bool			ok_alloc = true;
+	int			flags;
+	xfs_ino_t		ino;
 
 	/*
-	 * We do not have an agbp, so select an initial allocation
-	 * group for inode allocation.
+	 * Directories, symlinks, and regular files frequently allocate at least
+	 * one block, so factor that potential expansion when we examine whether
+	 * an AG has enough space for file creation.
 	 */
-	start_agno = xfs_ialloc_ag_select(*tpp, parent, mode);
-	if (start_agno == NULLAGNUMBER)
-		return 0;
+	if (S_ISDIR(mode))
+		start_agno = xfs_ialloc_next_ag(mp);
+	else {
+		start_agno = XFS_INO_TO_AGNO(mp, parent);
+		if (start_agno >= mp->m_maxagi)
+			start_agno = 0;
+	}
 
 	/*
 	 * If we have already hit the ceiling of inode blocks then clear
-	 * okalloc so we scan all available agi structures for a free
+	 * ok_alloc so we scan all available agi structures for a free
 	 * inode.
 	 *
 	 * Read rough value of mp->m_icount by percpu_counter_read_positive,
@@ -1764,8 +1766,7 @@ xfs_dialloc_select_ag(
 	if (igeo->maxicount &&
 	    percpu_counter_read_positive(&mp->m_icount) + igeo->ialloc_inos
 							> igeo->maxicount) {
-		noroom = true;
-		okalloc = false;
+		ok_alloc = false;
 	}
 
 	/*
@@ -1774,82 +1775,36 @@ xfs_dialloc_select_ag(
 	 * allocation groups upward, wrapping at the end.
 	 */
 	agno = start_agno;
+	flags = XFS_ALLOC_FLAG_TRYLOCK;
 	for (;;) {
 		pag = xfs_perag_get(mp, agno);
-		if (!pag->pagi_inodeok) {
-			xfs_ialloc_next_ag(mp);
-			goto nextag;
-		}
-
-		if (!pag->pagi_init) {
-			error = xfs_ialloc_pagi_init(mp, *tpp, agno);
-			if (error)
+		if (xfs_dialloc_good_ag(*tpp, pag, mode, flags, ok_alloc)) {
+			error = xfs_dialloc_try_ag(tpp, pag, parent,
+					&ino, ok_alloc);
+			if (error != -EAGAIN)
 				break;
 		}
 
-		/*
-		 * Do a first racy fast path check if this AG is usable.
-		 */
-		if (!pag->pagi_freecount && !okalloc)
-			goto nextag;
-
-		/*
-		 * Then read in the AGI buffer and recheck with the AGI buffer
-		 * lock held.
-		 */
-		error = xfs_ialloc_read_agi(mp, *tpp, agno, &agbp);
-		if (error)
-			break;
-
-		if (pag->pagi_freecount) {
-			xfs_perag_put(pag);
-			goto found_ag;
-		}
-
-		if (!okalloc)
-			goto nextag_relse_buffer;
-
-		error = xfs_ialloc_ag_alloc(*tpp, agbp);
-		if (error < 0) {
-			xfs_trans_brelse(*tpp, agbp);
-
-			if (error == -ENOSPC)
-				error = 0;
+		if (XFS_FORCED_SHUTDOWN(mp)) {
+			error = -EFSCORRUPTED;
 			break;
 		}
-
-		if (error == 0) {
-			/*
-			 * We successfully allocated space for an inode cluster
-			 * in this AG.  Roll the transaction so that we can
-			 * allocate one of the new inodes.
-			 */
-			ASSERT(pag->pagi_freecount > 0);
-			xfs_perag_put(pag);
-
-			error = xfs_dialloc_roll(tpp, agbp);
-			if (error) {
-				xfs_buf_relse(agbp);
-				return error;
+		if (++agno == mp->m_maxagi)
+			agno = 0;
+		if (agno == start_agno) {
+			if (!flags) {
+				error = -ENOSPC;
+				break;
 			}
-			goto found_ag;
+			flags = 0;
 		}
-
-nextag_relse_buffer:
-		xfs_trans_brelse(*tpp, agbp);
-nextag:
 		xfs_perag_put(pag);
-		if (++agno == mp->m_sb.sb_agcount)
-			agno = 0;
-		if (agno == start_agno)
-			return noroom ? -ENOSPC : 0;
 	}
 
+	if (!error)
+		*new_ino = ino;
 	xfs_perag_put(pag);
 	return error;
-found_ag:
-	*IO_agbp = agbp;
-	return 0;
 }
 
 /*
@@ -1935,12 +1890,12 @@ xfs_difree_inobt(
 	struct xfs_mount		*mp,
 	struct xfs_trans		*tp,
 	struct xfs_buf			*agbp,
+	struct xfs_perag		*pag,
 	xfs_agino_t			agino,
 	struct xfs_icluster		*xic,
 	struct xfs_inobt_rec_incore	*orec)
 {
 	struct xfs_agi			*agi = agbp->b_addr;
-	xfs_agnumber_t			agno = be32_to_cpu(agi->agi_seqno);
 	struct xfs_btree_cur		*cur;
 	struct xfs_inobt_rec_incore	rec;
 	int				ilen;
@@ -1954,7 +1909,7 @@ xfs_difree_inobt(
 	/*
 	 * Initialize the cursor.
 	 */
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO);
+	cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
 
 	error = xfs_check_agi_freecount(cur, agi);
 	if (error)
@@ -2005,7 +1960,8 @@ xfs_difree_inobt(
 		struct xfs_perag	*pag = agbp->b_pag;
 
 		xic->deleted = true;
-		xic->first_ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino);
+		xic->first_ino = XFS_AGINO_TO_INO(mp, pag->pag_agno,
+				rec.ir_startino);
 		xic->alloc = xfs_inobt_irec_to_allocmask(&rec);
 
 		/*
@@ -2028,7 +1984,7 @@ xfs_difree_inobt(
 			goto error0;
 		}
 
-		xfs_difree_inode_chunk(tp, agno, &rec);
+		xfs_difree_inode_chunk(tp, pag->pag_agno, &rec);
 	} else {
 		xic->deleted = false;
 
@@ -2044,7 +2000,7 @@ xfs_difree_inobt(
 		 */
 		be32_add_cpu(&agi->agi_freecount, 1);
 		xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
-		agbp->b_pag->pagi_freecount++;
+		pag->pagi_freecount++;
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, 1);
 	}
 
@@ -2069,18 +2025,18 @@ xfs_difree_finobt(
 	struct xfs_mount		*mp,
 	struct xfs_trans		*tp,
 	struct xfs_buf			*agbp,
+	struct xfs_perag		*pag,
 	xfs_agino_t			agino,
 	struct xfs_inobt_rec_incore	*ibtrec) /* inobt record */
 {
 	struct xfs_agi			*agi = agbp->b_addr;
-	xfs_agnumber_t			agno = be32_to_cpu(agi->agi_seqno);
 	struct xfs_btree_cur		*cur;
 	struct xfs_inobt_rec_incore	rec;
 	int				offset = agino - ibtrec->ir_startino;
 	int				error;
 	int				i;
 
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_FINO);
+	cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_FINO);
 
 	error = xfs_inobt_lookup(cur, ibtrec->ir_startino, XFS_LOOKUP_EQ, &i);
 	if (error)
@@ -2178,36 +2134,33 @@ error:
  */
 int
 xfs_difree(
-	struct xfs_trans	*tp,		/* transaction pointer */
-	xfs_ino_t		inode,		/* inode to be freed */
-	struct xfs_icluster	*xic)	/* cluster info if deleted */
+	struct xfs_trans	*tp,
+	struct xfs_perag	*pag,
+	xfs_ino_t		inode,
+	struct xfs_icluster	*xic)
 {
 	/* REFERENCED */
 	xfs_agblock_t		agbno;	/* block number containing inode */
 	struct xfs_buf		*agbp;	/* buffer for allocation group header */
 	xfs_agino_t		agino;	/* allocation group inode number */
-	xfs_agnumber_t		agno;	/* allocation group number */
 	int			error;	/* error return value */
-	struct xfs_mount	*mp;	/* mount structure for filesystem */
+	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_inobt_rec_incore rec;/* btree record */
 
-	mp = tp->t_mountp;
-
 	/*
 	 * Break up inode number into its components.
 	 */
-	agno = XFS_INO_TO_AGNO(mp, inode);
-	if (agno >= mp->m_sb.sb_agcount)  {
-		xfs_warn(mp, "%s: agno >= mp->m_sb.sb_agcount (%d >= %d).",
-			__func__, agno, mp->m_sb.sb_agcount);
+	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);
 		ASSERT(0);
 		return -EINVAL;
 	}
 	agino = XFS_INO_TO_AGINO(mp, inode);
-	if (inode != XFS_AGINO_TO_INO(mp, agno, agino))  {
+	if (inode != XFS_AGINO_TO_INO(mp, pag->pag_agno, agino))  {
 		xfs_warn(mp, "%s: inode != XFS_AGINO_TO_INO() (%llu != %llu).",
 			__func__, (unsigned long long)inode,
-			(unsigned long long)XFS_AGINO_TO_INO(mp, agno, agino));
+			(unsigned long long)XFS_AGINO_TO_INO(mp, pag->pag_agno, agino));
 		ASSERT(0);
 		return -EINVAL;
 	}
@@ -2221,7 +2174,7 @@ xfs_difree(
 	/*
 	 * Get the allocation group header.
 	 */
-	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
+	error = xfs_ialloc_read_agi(mp, tp, pag->pag_agno, &agbp);
 	if (error) {
 		xfs_warn(mp, "%s: xfs_ialloc_read_agi() returned error %d.",
 			__func__, error);
@@ -2231,7 +2184,7 @@ xfs_difree(
 	/*
 	 * Fix up the inode allocation btree.
 	 */
-	error = xfs_difree_inobt(mp, tp, agbp, agino, xic, &rec);
+	error = xfs_difree_inobt(mp, tp, agbp, pag, agino, xic, &rec);
 	if (error)
 		goto error0;
 
@@ -2239,7 +2192,7 @@ xfs_difree(
 	 * Fix up the free inode btree.
 	 */
 	if (xfs_sb_version_hasfinobt(&mp->m_sb)) {
-		error = xfs_difree_finobt(mp, tp, agbp, agino, &rec);
+		error = xfs_difree_finobt(mp, tp, agbp, pag, agino, &rec);
 		if (error)
 			goto error0;
 	}
@@ -2254,7 +2207,7 @@ STATIC int
 xfs_imap_lookup(
 	struct xfs_mount	*mp,
 	struct xfs_trans	*tp,
-	xfs_agnumber_t		agno,
+	struct xfs_perag	*pag,
 	xfs_agino_t		agino,
 	xfs_agblock_t		agbno,
 	xfs_agblock_t		*chunk_agbno,
@@ -2267,11 +2220,11 @@ xfs_imap_lookup(
 	int			error;
 	int			i;
 
-	error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
+	error = xfs_ialloc_read_agi(mp, tp, pag->pag_agno, &agbp);
 	if (error) {
 		xfs_alert(mp,
 			"%s: xfs_ialloc_read_agi() returned error %d, agno %d",
-			__func__, error, agno);
+			__func__, error, pag->pag_agno);
 		return error;
 	}
 
@@ -2281,7 +2234,7 @@ xfs_imap_lookup(
 	 * we have a record, we need to ensure it contains the inode number
 	 * we are looking up.
 	 */
-	cur = xfs_inobt_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO);
+	cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
 	error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &i);
 	if (!error) {
 		if (i)
@@ -2315,42 +2268,44 @@ xfs_imap_lookup(
  */
 int
 xfs_imap(
-	xfs_mount_t	 *mp,	/* file system mount structure */
-	xfs_trans_t	 *tp,	/* transaction pointer */
-	xfs_ino_t	ino,	/* inode to locate */
-	struct xfs_imap	*imap,	/* location map structure */
-	uint		flags)	/* flags for inode btree lookup */
+	struct xfs_mount	 *mp,	/* file system mount structure */
+	struct xfs_trans	 *tp,	/* transaction pointer */
+	xfs_ino_t		ino,	/* inode to locate */
+	struct xfs_imap		*imap,	/* location map structure */
+	uint			flags)	/* flags for inode btree lookup */
 {
-	xfs_agblock_t	agbno;	/* block number of inode in the alloc group */
-	xfs_agino_t	agino;	/* inode number within alloc group */
-	xfs_agnumber_t	agno;	/* allocation group number */
-	xfs_agblock_t	chunk_agbno;	/* first block in inode chunk */
-	xfs_agblock_t	cluster_agbno;	/* first block in inode cluster */
-	int		error;	/* error code */
-	int		offset;	/* index of inode in its buffer */
-	xfs_agblock_t	offset_agbno;	/* blks from chunk start to inode */
+	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 */
+	xfs_agblock_t		cluster_agbno;	/* first block in inode cluster */
+	int			error;	/* error code */
+	int			offset;	/* index of inode in its buffer */
+	xfs_agblock_t		offset_agbno;	/* blks from chunk start to inode */
+	struct xfs_perag	*pag;
 
 	ASSERT(ino != NULLFSINO);
 
 	/*
 	 * Split up the inode number into its parts.
 	 */
-	agno = XFS_INO_TO_AGNO(mp, ino);
+	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
 	agino = XFS_INO_TO_AGINO(mp, ino);
 	agbno = XFS_AGINO_TO_AGBNO(mp, agino);
-	if (agno >= mp->m_sb.sb_agcount || agbno >= mp->m_sb.sb_agblocks ||
-	    ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
+	if (!pag || agbno >= mp->m_sb.sb_agblocks ||
+	    ino != XFS_AGINO_TO_INO(mp, pag->pag_agno, agino)) {
+		error = -EINVAL;
 #ifdef DEBUG
 		/*
 		 * Don't output diagnostic information for untrusted inodes
 		 * as they can be invalid without implying corruption.
 		 */
 		if (flags & XFS_IGET_UNTRUSTED)
-			return -EINVAL;
-		if (agno >= mp->m_sb.sb_agcount) {
+			goto out_drop;
+		if (!pag) {
 			xfs_alert(mp,
 				"%s: agno (%d) >= mp->m_sb.sb_agcount (%d)",
-				__func__, agno, mp->m_sb.sb_agcount);
+				__func__, XFS_INO_TO_AGNO(mp, ino),
+				mp->m_sb.sb_agcount);
 		}
 		if (agbno >= mp->m_sb.sb_agblocks) {
 			xfs_alert(mp,
@@ -2358,15 +2313,15 @@ xfs_imap(
 				__func__, (unsigned long long)agbno,
 				(unsigned long)mp->m_sb.sb_agblocks);
 		}
-		if (ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
+		if (pag && ino != XFS_AGINO_TO_INO(mp, pag->pag_agno, agino)) {
 			xfs_alert(mp,
 		"%s: ino (0x%llx) != XFS_AGINO_TO_INO() (0x%llx)",
 				__func__, ino,
-				XFS_AGINO_TO_INO(mp, agno, agino));
+				XFS_AGINO_TO_INO(mp, pag->pag_agno, agino));
 		}
 		xfs_stack_trace();
 #endif /* DEBUG */
-		return -EINVAL;
+		goto out_drop;
 	}
 
 	/*
@@ -2377,10 +2332,10 @@ xfs_imap(
 	 * in all cases where an untrusted inode number is passed.
 	 */
 	if (flags & XFS_IGET_UNTRUSTED) {
-		error = xfs_imap_lookup(mp, tp, agno, agino, agbno,
+		error = xfs_imap_lookup(mp, tp, pag, agino, agbno,
 					&chunk_agbno, &offset_agbno, flags);
 		if (error)
-			return error;
+			goto out_drop;
 		goto out_map;
 	}
 
@@ -2392,11 +2347,12 @@ xfs_imap(
 		offset = XFS_INO_TO_OFFSET(mp, ino);
 		ASSERT(offset < mp->m_sb.sb_inopblock);
 
-		imap->im_blkno = XFS_AGB_TO_DADDR(mp, agno, agbno);
+		imap->im_blkno = XFS_AGB_TO_DADDR(mp, pag->pag_agno, agbno);
 		imap->im_len = XFS_FSB_TO_BB(mp, 1);
 		imap->im_boffset = (unsigned short)(offset <<
 							mp->m_sb.sb_inodelog);
-		return 0;
+		error = 0;
+		goto out_drop;
 	}
 
 	/*
@@ -2408,10 +2364,10 @@ xfs_imap(
 		offset_agbno = agbno & M_IGEO(mp)->inoalign_mask;
 		chunk_agbno = agbno - offset_agbno;
 	} else {
-		error = xfs_imap_lookup(mp, tp, agno, agino, agbno,
+		error = xfs_imap_lookup(mp, tp, pag, agino, agbno,
 					&chunk_agbno, &offset_agbno, flags);
 		if (error)
-			return error;
+			goto out_drop;
 	}
 
 out_map:
@@ -2422,7 +2378,7 @@ out_map:
 	offset = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
 		XFS_INO_TO_OFFSET(mp, ino);
 
-	imap->im_blkno = XFS_AGB_TO_DADDR(mp, agno, cluster_agbno);
+	imap->im_blkno = XFS_AGB_TO_DADDR(mp, pag->pag_agno, cluster_agbno);
 	imap->im_len = XFS_FSB_TO_BB(mp, M_IGEO(mp)->blocks_per_cluster);
 	imap->im_boffset = (unsigned short)(offset << mp->m_sb.sb_inodelog);
 
@@ -2439,9 +2395,13 @@ out_map:
 			__func__, (unsigned long long) imap->im_blkno,
 			(unsigned long long) imap->im_len,
 			XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks));
-		return -EINVAL;
+		error = -EINVAL;
+		goto out_drop;
 	}
-	return 0;
+	error = 0;
+out_drop:
+	xfs_perag_put(pag);
+	return error;
 }
 
 /*