selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 1444 insertions, 0 deletions

diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
new file mode 100644
index 000000000..1b36cf12d
--- /dev/null
+++ b/fs/xfs/xfs_trans.c
@@ -0,0 +1,1444 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
+ * Copyright (C) 2010 Red Hat, Inc.
+ * All Rights Reserved.
+ */
+#include "xfs_platform.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_extent_busy.h"
+#include "xfs_quota.h"
+#include "xfs_trans.h"
+#include "xfs_trans_priv.h"
+#include "xfs_log.h"
+#include "xfs_log_priv.h"
+#include "xfs_trace.h"
+#include "xfs_error.h"
+#include "xfs_defer.h"
+#include "xfs_inode.h"
+#include "xfs_dquot_item.h"
+#include "xfs_dquot.h"
+#include "xfs_icache.h"
+#include "xfs_rtbitmap.h"
+#include "xfs_rtgroup.h"
+#include "xfs_sb.h"
+
+struct kmem_cache	*xfs_trans_cache;
+
+#if defined(CONFIG_TRACEPOINTS)
+static void
+xfs_trans_trace_reservations(
+	struct xfs_mount	*mp)
+{
+	struct xfs_trans_res	*res;
+	struct xfs_trans_res	*end_res;
+	int			i;
+
+	res = (struct xfs_trans_res *)M_RES(mp);
+	end_res = (struct xfs_trans_res *)(M_RES(mp) + 1);
+	for (i = 0; res < end_res; i++, res++)
+		trace_xfs_trans_resv_calc(mp, i, res);
+}
+#else
+# define xfs_trans_trace_reservations(mp)
+#endif
+
+/*
+ * Initialize the precomputed transaction reservation values
+ * in the mount structure.
+ */
+void
+xfs_trans_init(
+	struct xfs_mount	*mp)
+{
+	xfs_trans_resv_calc(mp, M_RES(mp));
+	xfs_trans_trace_reservations(mp);
+}
+
+/*
+ * Free the transaction structure.  If there is more clean up
+ * to do when the structure is freed, add it here.
+ */
+STATIC void
+xfs_trans_free(
+	struct xfs_trans	*tp)
+{
+	xfs_extent_busy_sort(&tp->t_busy);
+	xfs_extent_busy_clear(&tp->t_busy, false);
+
+	trace_xfs_trans_free(tp, _RET_IP_);
+	xfs_trans_clear_context(tp);
+	if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT))
+		sb_end_intwrite(tp->t_mountp->m_super);
+	xfs_trans_free_dqinfo(tp);
+	kmem_cache_free(xfs_trans_cache, tp);
+}
+
+/*
+ * This is called to create a new transaction which will share the
+ * permanent log reservation of the given transaction.  The remaining
+ * unused block and rt extent reservations are also inherited.  This
+ * implies that the original transaction is no longer allowed to allocate
+ * blocks.  Locks and log items, however, are no inherited.  They must
+ * be added to the new transaction explicitly.
+ */
+STATIC struct xfs_trans *
+xfs_trans_dup(
+	struct xfs_trans	*tp)
+{
+	struct xfs_trans	*ntp;
+
+	trace_xfs_trans_dup(tp, _RET_IP_);
+
+	ntp = kmem_cache_zalloc(xfs_trans_cache, GFP_KERNEL | __GFP_NOFAIL);
+
+	/*
+	 * Initialize the new transaction structure.
+	 */
+	ntp->t_mountp = tp->t_mountp;
+	INIT_LIST_HEAD(&ntp->t_items);
+	INIT_LIST_HEAD(&ntp->t_busy);
+	INIT_LIST_HEAD(&ntp->t_dfops);
+	ntp->t_highest_agno = NULLAGNUMBER;
+
+	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
+	ASSERT(tp->t_ticket != NULL);
+
+	ntp->t_flags = XFS_TRANS_PERM_LOG_RES |
+		       (tp->t_flags & XFS_TRANS_RESERVE) |
+		       (tp->t_flags & XFS_TRANS_NO_WRITECOUNT) |
+		       (tp->t_flags & XFS_TRANS_RES_FDBLKS);
+	/* We gave our writer reference to the new transaction */
+	tp->t_flags |= XFS_TRANS_NO_WRITECOUNT;
+	ntp->t_ticket = xfs_log_ticket_get(tp->t_ticket);
+
+	ASSERT(tp->t_blk_res >= tp->t_blk_res_used);
+	ntp->t_blk_res = tp->t_blk_res - tp->t_blk_res_used;
+	tp->t_blk_res = tp->t_blk_res_used;
+
+	ntp->t_rtx_res = tp->t_rtx_res - tp->t_rtx_res_used;
+	tp->t_rtx_res = tp->t_rtx_res_used;
+
+	/* move deferred ops over to the new tp */
+	xfs_defer_move(ntp, tp);
+
+	xfs_trans_dup_dqinfo(tp, ntp);
+	return ntp;
+}
+
+/*
+ * This is called to reserve free disk blocks and log space for the given
+ * transaction before allocating any resources within the transaction.
+ *
+ * This will return ENOSPC if there are not enough blocks available.
+ * It will sleep waiting for available log space.
+ *
+ * This does not do quota reservations. That typically is done by the caller
+ * afterwards.
+ */
+static int
+xfs_trans_reserve(
+	struct xfs_trans	*tp,
+	struct xfs_trans_res	*resp,
+	uint			blocks,
+	uint			rtextents)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	int			error = 0;
+	bool			rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;
+
+	ASSERT(resp->tr_logres > 0);
+
+	/*
+	 * Attempt to reserve the needed disk blocks by decrementing the number
+	 * needed from the number available.  This will fail if the count would
+	 * go below zero.
+	 */
+	if (blocks > 0) {
+		error = xfs_dec_fdblocks(mp, blocks, rsvd);
+		if (error != 0)
+			return -ENOSPC;
+		tp->t_blk_res += blocks;
+	}
+
+	/*
+	 * Reserve the log space needed for this transaction.
+	 */
+	if (resp->tr_logflags & XFS_TRANS_PERM_LOG_RES)
+		tp->t_flags |= XFS_TRANS_PERM_LOG_RES;
+	error = xfs_log_reserve(mp, resp->tr_logres, resp->tr_logcount,
+			&tp->t_ticket, (tp->t_flags & XFS_TRANS_PERM_LOG_RES));
+	if (error)
+		goto undo_blocks;
+
+	tp->t_log_res = resp->tr_logres;
+	tp->t_log_count = resp->tr_logcount;
+
+	/*
+	 * Attempt to reserve the needed realtime extents by decrementing the
+	 * number needed from the number available.  This will fail if the
+	 * count would go below zero.
+	 */
+	if (rtextents > 0) {
+		error = xfs_dec_frextents(mp, rtextents);
+		if (error) {
+			error = -ENOSPC;
+			goto undo_log;
+		}
+		tp->t_rtx_res += rtextents;
+	}
+
+	return 0;
+
+undo_log:
+	xfs_log_ticket_ungrant(mp->m_log, tp->t_ticket);
+	tp->t_ticket = NULL;
+	tp->t_log_res = 0;
+	tp->t_flags &= ~XFS_TRANS_PERM_LOG_RES;
+undo_blocks:
+	if (blocks > 0) {
+		xfs_add_fdblocks(mp, blocks);
+		tp->t_blk_res = 0;
+	}
+	return error;
+}
+
+static struct xfs_trans *
+__xfs_trans_alloc(
+	struct xfs_mount	*mp,
+	uint			flags)
+{
+	struct xfs_trans	*tp;
+
+	ASSERT(!(flags & XFS_TRANS_RES_FDBLKS) || xfs_has_lazysbcount(mp));
+
+	tp = kmem_cache_zalloc(xfs_trans_cache, GFP_KERNEL | __GFP_NOFAIL);
+	if (!(flags & XFS_TRANS_NO_WRITECOUNT))
+		sb_start_intwrite(mp->m_super);
+	xfs_trans_set_context(tp);
+	tp->t_flags = flags;
+	tp->t_mountp = mp;
+	INIT_LIST_HEAD(&tp->t_items);
+	INIT_LIST_HEAD(&tp->t_busy);
+	INIT_LIST_HEAD(&tp->t_dfops);
+	tp->t_highest_agno = NULLAGNUMBER;
+	return tp;
+}
+
+int
+xfs_trans_alloc(
+	struct xfs_mount	*mp,
+	struct xfs_trans_res	*resp,
+	uint			blocks,
+	uint			rtextents,
+	uint			flags,
+	struct xfs_trans	**tpp)
+{
+	struct xfs_trans	*tp;
+	bool			want_retry = true;
+	int			error;
+
+	ASSERT(resp->tr_logres > 0);
+
+	/*
+	 * Allocate the handle before we do our freeze accounting and setting up
+	 * GFP_NOFS allocation context so that we avoid lockdep false positives
+	 * by doing GFP_KERNEL allocations inside sb_start_intwrite().
+	 */
+retry:
+	tp = __xfs_trans_alloc(mp, flags);
+	WARN_ON(mp->m_super->s_writers.frozen == SB_FREEZE_COMPLETE);
+	error = xfs_trans_reserve(tp, resp, blocks, rtextents);
+	if (error == -ENOSPC && want_retry) {
+		xfs_trans_cancel(tp);
+
+		/*
+		 * We weren't able to reserve enough space for the transaction.
+		 * Flush the other speculative space allocations to free space.
+		 * Do not perform a synchronous scan because callers can hold
+		 * other locks.
+		 */
+		error = xfs_blockgc_flush_all(mp);
+		if (error)
+			return error;
+		want_retry = false;
+		goto retry;
+	}
+	if (error) {
+		xfs_trans_cancel(tp);
+		return error;
+	}
+
+	trace_xfs_trans_alloc(tp, _RET_IP_);
+
+	*tpp = tp;
+	return 0;
+}
+
+/*
+ * Create an empty transaction with no reservation.  This is a defensive
+ * mechanism for routines that query metadata without actually modifying them --
+ * if the metadata being queried is somehow cross-linked (think a btree block
+ * pointer that points higher in the tree), we risk deadlock.  However, blocks
+ * grabbed as part of a transaction can be re-grabbed.  The verifiers will
+ * notice the corrupt block and the operation will fail back to userspace
+ * without deadlocking.
+ *
+ * Note the zero-length reservation; this transaction MUST be cancelled without
+ * any dirty data.
+ *
+ * Callers should obtain freeze protection to avoid a conflict with fs freezing
+ * where we can be grabbing buffers at the same time that freeze is trying to
+ * drain the buffer LRU list.
+ */
+struct xfs_trans *
+xfs_trans_alloc_empty(
+	struct xfs_mount		*mp)
+{
+	return __xfs_trans_alloc(mp, XFS_TRANS_NO_WRITECOUNT);
+}
+
+/*
+ * Record the indicated change to the given field for application
+ * to the file system's superblock when the transaction commits.
+ * For now, just store the change in the transaction structure.
+ *
+ * Mark the transaction structure to indicate that the superblock
+ * needs to be updated before committing.
+ *
+ * Because we may not be keeping track of allocated/free inodes and
+ * used filesystem blocks in the superblock, we do not mark the
+ * superblock dirty in this transaction if we modify these fields.
+ * We still need to update the transaction deltas so that they get
+ * applied to the incore superblock, but we don't want them to
+ * cause the superblock to get locked and logged if these are the
+ * only fields in the superblock that the transaction modifies.
+ */
+void
+xfs_trans_mod_sb(
+	xfs_trans_t	*tp,
+	uint		field,
+	int64_t		delta)
+{
+	uint32_t	flags = (XFS_TRANS_DIRTY|XFS_TRANS_SB_DIRTY);
+	xfs_mount_t	*mp = tp->t_mountp;
+
+	switch (field) {
+	case XFS_TRANS_SB_ICOUNT:
+		tp->t_icount_delta += delta;
+		if (xfs_has_lazysbcount(mp))
+			flags &= ~XFS_TRANS_SB_DIRTY;
+		break;
+	case XFS_TRANS_SB_IFREE:
+		tp->t_ifree_delta += delta;
+		if (xfs_has_lazysbcount(mp))
+			flags &= ~XFS_TRANS_SB_DIRTY;
+		break;
+	case XFS_TRANS_SB_FDBLOCKS:
+		/*
+		 * Track the number of blocks allocated in the transaction.
+		 * Make sure it does not exceed the number reserved. If so,
+		 * shutdown as this can lead to accounting inconsistency.
+		 */
+		if (delta < 0) {
+			tp->t_blk_res_used += (uint)-delta;
+			if (tp->t_blk_res_used > tp->t_blk_res)
+				xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+		} else if (delta > 0 && (tp->t_flags & XFS_TRANS_RES_FDBLKS)) {
+			int64_t	blkres_delta;
+
+			/*
+			 * Return freed blocks directly to the reservation
+			 * instead of the global pool, being careful not to
+			 * overflow the trans counter. This is used to preserve
+			 * reservation across chains of transaction rolls that
+			 * repeatedly free and allocate blocks.
+			 */
+			blkres_delta = min_t(int64_t, delta,
+					     UINT_MAX - tp->t_blk_res);
+			tp->t_blk_res += blkres_delta;
+			delta -= blkres_delta;
+		}
+		tp->t_fdblocks_delta += delta;
+		if (xfs_has_lazysbcount(mp))
+			flags &= ~XFS_TRANS_SB_DIRTY;
+		break;
+	case XFS_TRANS_SB_RES_FDBLOCKS:
+		/*
+		 * The allocation has already been applied to the
+		 * in-core superblock's counter.  This should only
+		 * be applied to the on-disk superblock.
+		 */
+		tp->t_res_fdblocks_delta += delta;
+		if (xfs_has_lazysbcount(mp))
+			flags &= ~XFS_TRANS_SB_DIRTY;
+		break;
+	case XFS_TRANS_SB_FREXTENTS:
+		/*
+		 * Track the number of blocks allocated in the
+		 * transaction.  Make sure it does not exceed the
+		 * number reserved.
+		 */
+		if (delta < 0) {
+			tp->t_rtx_res_used += (uint)-delta;
+			ASSERT(tp->t_rtx_res_used <= tp->t_rtx_res);
+		}
+		tp->t_frextents_delta += delta;
+		if (xfs_has_rtgroups(mp))
+			flags &= ~XFS_TRANS_SB_DIRTY;
+		break;
+	case XFS_TRANS_SB_RES_FREXTENTS:
+		/*
+		 * The allocation has already been applied to the
+		 * in-core superblock's counter.  This should only
+		 * be applied to the on-disk superblock.
+		 */
+		ASSERT(delta < 0);
+		tp->t_res_frextents_delta += delta;
+		if (xfs_has_rtgroups(mp))
+			flags &= ~XFS_TRANS_SB_DIRTY;
+		break;
+	case XFS_TRANS_SB_DBLOCKS:
+		tp->t_dblocks_delta += delta;
+		break;
+	case XFS_TRANS_SB_AGCOUNT:
+		ASSERT(delta > 0);
+		tp->t_agcount_delta += delta;
+		break;
+	case XFS_TRANS_SB_IMAXPCT:
+		tp->t_imaxpct_delta += delta;
+		break;
+	case XFS_TRANS_SB_REXTSIZE:
+		tp->t_rextsize_delta += delta;
+		break;
+	case XFS_TRANS_SB_RBMBLOCKS:
+		tp->t_rbmblocks_delta += delta;
+		break;
+	case XFS_TRANS_SB_RBLOCKS:
+		tp->t_rblocks_delta += delta;
+		break;
+	case XFS_TRANS_SB_REXTENTS:
+		tp->t_rextents_delta += delta;
+		break;
+	case XFS_TRANS_SB_REXTSLOG:
+		tp->t_rextslog_delta += delta;
+		break;
+	case XFS_TRANS_SB_RGCOUNT:
+		ASSERT(delta > 0);
+		tp->t_rgcount_delta += delta;
+		break;
+	default:
+		ASSERT(0);
+		return;
+	}
+
+	tp->t_flags |= flags;
+}
+
+/*
+ * xfs_trans_apply_sb_deltas() is called from the commit code
+ * to bring the superblock buffer into the current transaction
+ * and modify it as requested by earlier calls to xfs_trans_mod_sb().
+ *
+ * For now we just look at each field allowed to change and change
+ * it if necessary.
+ */
+STATIC void
+xfs_trans_apply_sb_deltas(
+	struct xfs_trans	*tp)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xfs_buf		*bp = xfs_trans_getsb(tp);
+	struct xfs_dsb		*sbp = bp->b_addr;
+	int			whole = 0;
+
+	/*
+	 * Only update the superblock counters if we are logging them
+	 */
+	if (!xfs_has_lazysbcount(mp)) {
+		if (tp->t_icount_delta)
+			be64_add_cpu(&sbp->sb_icount, tp->t_icount_delta);
+		if (tp->t_ifree_delta)
+			be64_add_cpu(&sbp->sb_ifree, tp->t_ifree_delta);
+		if (tp->t_fdblocks_delta)
+			be64_add_cpu(&sbp->sb_fdblocks, tp->t_fdblocks_delta);
+		if (tp->t_res_fdblocks_delta)
+			be64_add_cpu(&sbp->sb_fdblocks, tp->t_res_fdblocks_delta);
+	}
+
+	/*
+	 * sb_frextents was added to the lazy sb counters when the rt groups
+	 * feature was introduced.  This is possible because we know that all
+	 * kernels supporting rtgroups will also recompute frextents from the
+	 * realtime bitmap.
+	 *
+	 * For older file systems, updating frextents requires careful handling
+	 * because we cannot rely on log recovery in older kernels to recompute
+	 * the value from the rtbitmap.  This means that the ondisk frextents
+	 * must be consistent with the rtbitmap.
+	 *
+	 * Therefore, log the frextents change to the ondisk superblock and
+	 * update the incore superblock so that future calls to xfs_log_sb
+	 * write the correct value ondisk.
+	 */
+	if ((tp->t_frextents_delta || tp->t_res_frextents_delta) &&
+	    !xfs_has_rtgroups(mp)) {
+		int64_t			rtxdelta;
+
+		rtxdelta = tp->t_frextents_delta + tp->t_res_frextents_delta;
+
+		spin_lock(&mp->m_sb_lock);
+		be64_add_cpu(&sbp->sb_frextents, rtxdelta);
+		mp->m_sb.sb_frextents += rtxdelta;
+		spin_unlock(&mp->m_sb_lock);
+	}
+
+	if (tp->t_dblocks_delta) {
+		be64_add_cpu(&sbp->sb_dblocks, tp->t_dblocks_delta);
+		mp->m_ddev_targp->bt_nr_sectors +=
+			XFS_FSB_TO_BB(mp, tp->t_dblocks_delta);
+		whole = 1;
+	}
+	if (tp->t_agcount_delta) {
+		be32_add_cpu(&sbp->sb_agcount, tp->t_agcount_delta);
+		whole = 1;
+	}
+	if (tp->t_imaxpct_delta) {
+		sbp->sb_imax_pct += tp->t_imaxpct_delta;
+		whole = 1;
+	}
+	if (tp->t_rextsize_delta) {
+		be32_add_cpu(&sbp->sb_rextsize, tp->t_rextsize_delta);
+
+		/*
+		 * Because the ondisk sb records rtgroup size in units of rt
+		 * extents, any time we update the rt extent size we have to
+		 * recompute the ondisk rtgroup block log.  The incore values
+		 * will be recomputed in xfs_trans_unreserve_and_mod_sb.
+		 */
+		if (xfs_has_rtgroups(mp)) {
+			sbp->sb_rgblklog = xfs_compute_rgblklog(
+						be32_to_cpu(sbp->sb_rgextents),
+						be32_to_cpu(sbp->sb_rextsize));
+		}
+		whole = 1;
+	}
+	if (tp->t_rbmblocks_delta) {
+		be32_add_cpu(&sbp->sb_rbmblocks, tp->t_rbmblocks_delta);
+		whole = 1;
+	}
+	if (tp->t_rblocks_delta) {
+		be64_add_cpu(&sbp->sb_rblocks, tp->t_rblocks_delta);
+		mp->m_rtdev_targp->bt_nr_sectors +=
+			XFS_FSB_TO_BB(mp, tp->t_rblocks_delta);
+		whole = 1;
+	}
+	if (tp->t_rextents_delta) {
+		be64_add_cpu(&sbp->sb_rextents, tp->t_rextents_delta);
+		whole = 1;
+	}
+	if (tp->t_rextslog_delta) {
+		sbp->sb_rextslog += tp->t_rextslog_delta;
+		whole = 1;
+	}
+	if (tp->t_rgcount_delta) {
+		be32_add_cpu(&sbp->sb_rgcount, tp->t_rgcount_delta);
+		whole = 1;
+	}
+
+	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SB_BUF);
+	if (whole)
+		/*
+		 * Log the whole thing, the fields are noncontiguous.
+		 */
+		xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsb) - 1);
+	else
+		/*
+		 * Since all the modifiable fields are contiguous, we
+		 * can get away with this.
+		 */
+		xfs_trans_log_buf(tp, bp, offsetof(struct xfs_dsb, sb_icount),
+				  offsetof(struct xfs_dsb, sb_frextents) +
+				  sizeof(sbp->sb_frextents) - 1);
+}
+
+/*
+ * xfs_trans_unreserve_and_mod_sb() is called to release unused reservations and
+ * apply superblock counter changes to the in-core superblock.  The
+ * t_res_fdblocks_delta and t_res_frextents_delta fields are explicitly NOT
+ * applied to the in-core superblock.  The idea is that that has already been
+ * done.
+ *
+ * If we are not logging superblock counters, then the inode allocated/free and
+ * used block counts are not updated in the on disk superblock. In this case,
+ * XFS_TRANS_SB_DIRTY will not be set when the transaction is updated but we
+ * still need to update the incore superblock with the changes.
+ *
+ * Deltas for the inode count are +/-64, hence we use a large batch size of 128
+ * so we don't need to take the counter lock on every update.
+ */
+#define XFS_ICOUNT_BATCH	128
+
+void
+xfs_trans_unreserve_and_mod_sb(
+	struct xfs_trans	*tp)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	int64_t			blkdelta = tp->t_blk_res;
+	int64_t			rtxdelta = tp->t_rtx_res;
+	int64_t			idelta = 0;
+	int64_t			ifreedelta = 0;
+
+	/*
+	 * Calculate the deltas.
+	 *
+	 * t_fdblocks_delta and t_frextents_delta can be positive or negative:
+	 *
+	 *  - positive values indicate blocks freed in the transaction.
+	 *  - negative values indicate blocks allocated in the transaction
+	 *
+	 * Negative values can only happen if the transaction has a block
+	 * reservation that covers the allocated block.  The end result is
+	 * that the calculated delta values must always be positive and we
+	 * can only put back previous allocated or reserved blocks here.
+	 */
+	ASSERT(tp->t_blk_res || tp->t_fdblocks_delta >= 0);
+	if (xfs_has_lazysbcount(mp) || (tp->t_flags & XFS_TRANS_SB_DIRTY)) {
+	        blkdelta += tp->t_fdblocks_delta;
+		ASSERT(blkdelta >= 0);
+	}
+
+	ASSERT(tp->t_rtx_res || tp->t_frextents_delta >= 0);
+	if (xfs_has_rtgroups(mp) || (tp->t_flags & XFS_TRANS_SB_DIRTY)) {
+		rtxdelta += tp->t_frextents_delta;
+		ASSERT(rtxdelta >= 0);
+	}
+
+	if (xfs_has_lazysbcount(mp) || (tp->t_flags & XFS_TRANS_SB_DIRTY)) {
+		idelta = tp->t_icount_delta;
+		ifreedelta = tp->t_ifree_delta;
+	}
+
+	/* apply the per-cpu counters */
+	if (blkdelta)
+		xfs_add_fdblocks(mp, blkdelta);
+
+	if (idelta)
+		percpu_counter_add_batch(&mp->m_icount, idelta,
+					 XFS_ICOUNT_BATCH);
+
+	if (ifreedelta)
+		percpu_counter_add(&mp->m_ifree, ifreedelta);
+
+	if (rtxdelta)
+		xfs_add_frextents(mp, rtxdelta);
+
+	if (!(tp->t_flags & XFS_TRANS_SB_DIRTY))
+		return;
+
+	/* apply remaining deltas */
+	spin_lock(&mp->m_sb_lock);
+	mp->m_sb.sb_fdblocks += tp->t_fdblocks_delta + tp->t_res_fdblocks_delta;
+	mp->m_sb.sb_icount += idelta;
+	mp->m_sb.sb_ifree += ifreedelta;
+	/*
+	 * Do not touch sb_frextents here because it is handled in
+	 * xfs_trans_apply_sb_deltas for file systems where it isn't a lazy
+	 * counter anyway.
+	 */
+	mp->m_sb.sb_dblocks += tp->t_dblocks_delta;
+	mp->m_sb.sb_agcount += tp->t_agcount_delta;
+	mp->m_sb.sb_imax_pct += tp->t_imaxpct_delta;
+	if (tp->t_rextsize_delta)
+		xfs_mount_sb_set_rextsize(mp, &mp->m_sb,
+				mp->m_sb.sb_rextsize + tp->t_rextsize_delta);
+	mp->m_sb.sb_rbmblocks += tp->t_rbmblocks_delta;
+	mp->m_sb.sb_rblocks += tp->t_rblocks_delta;
+	mp->m_sb.sb_rextents += tp->t_rextents_delta;
+	mp->m_sb.sb_rextslog += tp->t_rextslog_delta;
+	mp->m_sb.sb_rgcount += tp->t_rgcount_delta;
+	spin_unlock(&mp->m_sb_lock);
+
+	/*
+	 * Debug checks outside of the spinlock so they don't lock up the
+	 * machine if they fail.
+	 */
+	ASSERT(mp->m_sb.sb_imax_pct >= 0);
+	ASSERT(mp->m_sb.sb_rextslog >= 0);
+}
+
+/* Add the given log item to the transaction's list of log items. */
+void
+xfs_trans_add_item(
+	struct xfs_trans	*tp,
+	struct xfs_log_item	*lip)
+{
+	ASSERT(lip->li_log == tp->t_mountp->m_log);
+	ASSERT(lip->li_ailp == tp->t_mountp->m_ail);
+	ASSERT(list_empty(&lip->li_trans));
+	ASSERT(!test_bit(XFS_LI_DIRTY, &lip->li_flags));
+
+	list_add_tail(&lip->li_trans, &tp->t_items);
+	trace_xfs_trans_add_item(tp, _RET_IP_);
+}
+
+/*
+ * Unlink the log item from the transaction. the log item is no longer
+ * considered dirty in this transaction, as the linked transaction has
+ * finished, either by abort or commit completion.
+ */
+void
+xfs_trans_del_item(
+	struct xfs_log_item	*lip)
+{
+	clear_bit(XFS_LI_DIRTY, &lip->li_flags);
+	list_del_init(&lip->li_trans);
+}
+
+/* Detach and unlock all of the items in a transaction */
+static void
+xfs_trans_free_items(
+	struct xfs_trans	*tp,
+	bool			abort)
+{
+	struct xfs_log_item	*lip, *next;
+
+	trace_xfs_trans_free_items(tp, _RET_IP_);
+
+	list_for_each_entry_safe(lip, next, &tp->t_items, li_trans) {
+		xfs_trans_del_item(lip);
+		if (abort) {
+			trace_xfs_trans_free_abort(lip);
+			set_bit(XFS_LI_ABORTED, &lip->li_flags);
+		}
+		if (lip->li_ops->iop_release)
+			lip->li_ops->iop_release(lip);
+	}
+}
+
+/*
+ * Sort transaction items prior to running precommit operations. This will
+ * attempt to order the items such that they will always be locked in the same
+ * order. Items that have no sort function are moved to the end of the list
+ * and so are locked last.
+ *
+ * This may need refinement as different types of objects add sort functions.
+ *
+ * Function is more complex than it needs to be because we are comparing 64 bit
+ * values and the function only returns 32 bit values.
+ */
+static int
+xfs_trans_precommit_sort(
+	void			*unused_arg,
+	const struct list_head	*a,
+	const struct list_head	*b)
+{
+	struct xfs_log_item	*lia = container_of(a,
+					struct xfs_log_item, li_trans);
+	struct xfs_log_item	*lib = container_of(b,
+					struct xfs_log_item, li_trans);
+	int64_t			diff;
+
+	/*
+	 * If both items are non-sortable, leave them alone. If only one is
+	 * sortable, move the non-sortable item towards the end of the list.
+	 */
+	if (!lia->li_ops->iop_sort && !lib->li_ops->iop_sort)
+		return 0;
+	if (!lia->li_ops->iop_sort)
+		return 1;
+	if (!lib->li_ops->iop_sort)
+		return -1;
+
+	diff = lia->li_ops->iop_sort(lia) - lib->li_ops->iop_sort(lib);
+	if (diff < 0)
+		return -1;
+	if (diff > 0)
+		return 1;
+	return 0;
+}
+
+/*
+ * Run transaction precommit functions.
+ *
+ * If there is an error in any of the callouts, then stop immediately and
+ * trigger a shutdown to abort the transaction. There is no recovery possible
+ * from errors at this point as the transaction is dirty....
+ */
+static int
+xfs_trans_run_precommits(
+	struct xfs_trans	*tp)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xfs_log_item	*lip, *n;
+	int			error = 0;
+
+	/*
+	 * Sort the item list to avoid ABBA deadlocks with other transactions
+	 * running precommit operations that lock multiple shared items such as
+	 * inode cluster buffers.
+	 */
+	list_sort(NULL, &tp->t_items, xfs_trans_precommit_sort);
+
+	/*
+	 * Precommit operations can remove the log item from the transaction
+	 * if the log item exists purely to delay modifications until they
+	 * can be ordered against other operations. Hence we have to use
+	 * list_for_each_entry_safe() here.
+	 */
+	list_for_each_entry_safe(lip, n, &tp->t_items, li_trans) {
+		if (!test_bit(XFS_LI_DIRTY, &lip->li_flags))
+			continue;
+		if (lip->li_ops->iop_precommit) {
+			error = lip->li_ops->iop_precommit(tp, lip);
+			if (error)
+				break;
+		}
+	}
+	if (error)
+		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+	return error;
+}
+
+/*
+ * Commit the given transaction to the log.
+ *
+ * XFS disk error handling mechanism is not based on a typical
+ * transaction abort mechanism. Logically after the filesystem
+ * gets marked 'SHUTDOWN', we can't let any new transactions
+ * be durable - ie. committed to disk - because some metadata might
+ * be inconsistent. In such cases, this returns an error, and the
+ * caller may assume that all locked objects joined to the transaction
+ * have already been unlocked as if the commit had succeeded.
+ * Do not reference the transaction structure after this call.
+ */
+static int
+__xfs_trans_commit(
+	struct xfs_trans	*tp,
+	bool			regrant)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xlog		*log = mp->m_log;
+	xfs_csn_t		commit_seq = 0;
+	int			error = 0;
+	int			sync = tp->t_flags & XFS_TRANS_SYNC;
+
+	trace_xfs_trans_commit(tp, _RET_IP_);
+
+	/*
+	 * Commit per-transaction changes that are not already tracked through
+	 * log items.  This can add dirty log items to the transaction.
+	 */
+	if (tp->t_flags & XFS_TRANS_SB_DIRTY)
+		xfs_trans_apply_sb_deltas(tp);
+	xfs_trans_apply_dquot_deltas(tp);
+
+	error = xfs_trans_run_precommits(tp);
+	if (error)
+		goto out_unreserve;
+
+	/*
+	 * If there is nothing to be logged by the transaction,
+	 * then unlock all of the items associated with the
+	 * transaction and free the transaction structure.
+	 * Also make sure to return any reserved blocks to
+	 * the free pool.
+	 */
+	if (!(tp->t_flags & XFS_TRANS_DIRTY))
+		goto out_unreserve;
+
+	/*
+	 * We must check against log shutdown here because we cannot abort log
+	 * items and leave them dirty, inconsistent and unpinned in memory while
+	 * the log is active. This leaves them open to being written back to
+	 * disk, and that will lead to on-disk corruption.
+	 */
+	if (xlog_is_shutdown(log)) {
+		error = -EIO;
+		goto out_unreserve;
+	}
+
+	ASSERT(tp->t_ticket != NULL);
+
+	xlog_cil_commit(log, tp, &commit_seq, regrant);
+
+	xfs_trans_free(tp);
+
+	/*
+	 * If the transaction needs to be synchronous, then force the
+	 * log out now and wait for it.
+	 */
+	if (sync) {
+		error = xfs_log_force_seq(mp, commit_seq, XFS_LOG_SYNC, NULL);
+		XFS_STATS_INC(mp, xs_trans_sync);
+	} else {
+		XFS_STATS_INC(mp, xs_trans_async);
+	}
+
+	return error;
+
+out_unreserve:
+	xfs_trans_unreserve_and_mod_sb(tp);
+
+	/*
+	 * It is indeed possible for the transaction to be not dirty but
+	 * the dqinfo portion to be.  All that means is that we have some
+	 * (non-persistent) quota reservations that need to be unreserved.
+	 */
+	xfs_trans_unreserve_and_mod_dquots(tp, true);
+	if (tp->t_ticket) {
+		if (regrant && !xlog_is_shutdown(log))
+			xfs_log_ticket_regrant(log, tp->t_ticket);
+		else
+			xfs_log_ticket_ungrant(log, tp->t_ticket);
+		tp->t_ticket = NULL;
+	}
+	xfs_trans_free_items(tp, !!error);
+	xfs_trans_free(tp);
+
+	XFS_STATS_INC(mp, xs_trans_empty);
+	return error;
+}
+
+int
+xfs_trans_commit(
+	struct xfs_trans	*tp)
+{
+	/*
+	 * Finish deferred items on final commit. Only permanent transactions
+	 * should ever have deferred ops.
+	 */
+	WARN_ON_ONCE(!list_empty(&tp->t_dfops) &&
+		     !(tp->t_flags & XFS_TRANS_PERM_LOG_RES));
+	if (tp->t_flags & XFS_TRANS_PERM_LOG_RES) {
+		int error = xfs_defer_finish_noroll(&tp);
+		if (error) {
+			xfs_trans_cancel(tp);
+			return error;
+		}
+	}
+
+	return __xfs_trans_commit(tp, false);
+}
+
+/*
+ * Unlock all of the transaction's items and free the transaction.  If the
+ * transaction is dirty, we must shut down the filesystem because there is no
+ * way to restore them to their previous state.
+ *
+ * If the transaction has made a log reservation, make sure to release it as
+ * well.
+ *
+ * This is a high level function (equivalent to xfs_trans_commit()) and so can
+ * be called after the transaction has effectively been aborted due to the mount
+ * being shut down. However, if the mount has not been shut down and the
+ * transaction is dirty we will shut the mount down and, in doing so, that
+ * guarantees that the log is shut down, too. Hence we don't need to be as
+ * careful with shutdown state and dirty items here as we need to be in
+ * xfs_trans_commit().
+ */
+void
+xfs_trans_cancel(
+	struct xfs_trans	*tp)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xlog		*log = mp->m_log;
+	bool			dirty = (tp->t_flags & XFS_TRANS_DIRTY);
+
+	trace_xfs_trans_cancel(tp, _RET_IP_);
+
+	/*
+	 * It's never valid to cancel a transaction with deferred ops attached,
+	 * because the transaction is effectively dirty.  Complain about this
+	 * loudly before freeing the in-memory defer items and shutting down the
+	 * filesystem.
+	 */
+	if (!list_empty(&tp->t_dfops)) {
+		ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
+		dirty = true;
+		xfs_defer_cancel(tp);
+	}
+
+	/*
+	 * See if the caller is relying on us to shut down the filesystem. We
+	 * only want an error report if there isn't already a shutdown in
+	 * progress, so we only need to check against the mount shutdown state
+	 * here.
+	 */
+	if (dirty && !xfs_is_shutdown(mp)) {
+		XFS_ERROR_REPORT("xfs_trans_cancel", XFS_ERRLEVEL_LOW, mp);
+		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+	}
+#ifdef DEBUG
+	/* Log items need to be consistent until the log is shut down. */
+	if (!dirty && !xlog_is_shutdown(log)) {
+		struct xfs_log_item *lip;
+
+		list_for_each_entry(lip, &tp->t_items, li_trans)
+			ASSERT(!xlog_item_is_intent_done(lip));
+	}
+#endif
+	xfs_trans_unreserve_and_mod_sb(tp);
+	xfs_trans_unreserve_and_mod_dquots(tp, false);
+
+	if (tp->t_ticket) {
+		xfs_log_ticket_ungrant(log, tp->t_ticket);
+		tp->t_ticket = NULL;
+	}
+
+	xfs_trans_free_items(tp, dirty);
+	xfs_trans_free(tp);
+}
+
+/*
+ * Roll from one trans in the sequence of PERMANENT transactions to the next:
+ * permanent transactions are only flushed out when committed with
+ * xfs_trans_commit(), but we still want as soon as possible to let chunks of it
+ * go to the log.  So we commit the chunk we've been working on and get a new
+ * transaction to continue.
+ */
+int
+xfs_trans_roll(
+	struct xfs_trans	**tpp)
+{
+	struct xfs_trans	*tp = *tpp;
+	unsigned int		log_res = tp->t_log_res;
+	unsigned int		log_count = tp->t_log_count;
+	int			error;
+
+	trace_xfs_trans_roll(tp, _RET_IP_);
+
+	ASSERT(log_res > 0);
+
+	/*
+	 * Copy the critical parameters from one trans to the next.
+	 */
+	*tpp = xfs_trans_dup(tp);
+
+	/*
+	 * Commit the current transaction.
+	 *
+	 * If this commit failed, then it'd just unlock those items that are not
+	 * marked ihold. That also means that a filesystem shutdown is in
+	 * progress.  The caller takes the responsibility to cancel the
+	 * duplicate transaction that gets returned.
+	 */
+	error = __xfs_trans_commit(tp, true);
+
+	tp = *tpp;
+	/*
+	 * __xfs_trans_commit cleared the NOFS flag by calling into
+	 * xfs_trans_free.  Set it again here before doing memory
+	 * allocations.
+	 */
+	xfs_trans_set_context(tp);
+
+	if (error)
+		return error;
+
+	/*
+	 * Reserve space in the log for the next transaction.
+	 *
+	 * This also pushes items in the AIL out to disk if they are taking up
+	 * space at the tail of the log that we want to use.  This requires that
+	 * either nothing be locked across this call, or that anything that is
+	 * locked be logged in the prior and the next transactions.
+	 */
+	error = xfs_log_regrant(tp->t_mountp, tp->t_ticket);
+	if (error)
+		return error;
+	tp->t_log_res = log_res;
+	tp->t_log_count = log_count;
+	return 0;
+}
+
+/*
+ * Allocate an transaction, lock and join the inode to it, and reserve quota.
+ *
+ * The caller must ensure that the on-disk dquots attached to this inode have
+ * already been allocated and initialized.  The caller is responsible for
+ * releasing ILOCK_EXCL if a new transaction is returned.
+ */
+int
+xfs_trans_alloc_inode(
+	struct xfs_inode	*ip,
+	struct xfs_trans_res	*resv,
+	unsigned int		dblocks,
+	unsigned int		rblocks,
+	bool			force,
+	struct xfs_trans	**tpp)
+{
+	struct xfs_trans	*tp;
+	struct xfs_mount	*mp = ip->i_mount;
+	bool			retried = false;
+	int			error;
+
+retry:
+	error = xfs_trans_alloc(mp, resv, dblocks,
+			xfs_extlen_to_rtxlen(mp, rblocks),
+			force ? XFS_TRANS_RESERVE : 0, &tp);
+	if (error)
+		return error;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, 0);
+
+	error = xfs_qm_dqattach_locked(ip, false);
+	if (error) {
+		/* Caller should have allocated the dquots! */
+		ASSERT(error != -ENOENT);
+		goto out_cancel;
+	}
+
+	error = xfs_trans_reserve_quota_nblks(tp, ip, dblocks, rblocks, force);
+	if ((error == -EDQUOT || error == -ENOSPC) && !retried) {
+		xfs_trans_cancel(tp);
+		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		xfs_blockgc_free_quota(ip, 0);
+		retried = true;
+		goto retry;
+	}
+	if (error)
+		goto out_cancel;
+
+	*tpp = tp;
+	return 0;
+
+out_cancel:
+	xfs_trans_cancel(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+}
+
+/*
+ * Try to reserve more blocks for a transaction.
+ *
+ * This is for callers that need to attach resources to a transaction, scan
+ * those resources to determine the space reservation requirements, and then
+ * modify the attached resources.  In other words, online repair.  This can
+ * fail due to ENOSPC, so the caller must be able to cancel the transaction
+ * without shutting down the fs.
+ */
+int
+xfs_trans_reserve_more(
+	struct xfs_trans	*tp,
+	unsigned int		blocks,
+	unsigned int		rtextents)
+{
+	bool			rsvd = tp->t_flags & XFS_TRANS_RESERVE;
+
+	if (blocks && xfs_dec_fdblocks(tp->t_mountp, blocks, rsvd))
+		return -ENOSPC;
+	if (rtextents && xfs_dec_frextents(tp->t_mountp, rtextents)) {
+		if (blocks)
+			xfs_add_fdblocks(tp->t_mountp, blocks);
+		return -ENOSPC;
+	}
+	tp->t_blk_res += blocks;
+	tp->t_rtx_res += rtextents;
+	return 0;
+}
+
+/*
+ * Try to reserve more blocks and file quota for a transaction.  Same
+ * conditions of usage as xfs_trans_reserve_more.
+ */
+int
+xfs_trans_reserve_more_inode(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*ip,
+	unsigned int		dblocks,
+	unsigned int		rblocks,
+	bool			force_quota)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	unsigned int		rtx = xfs_extlen_to_rtxlen(mp, rblocks);
+	int			error;
+
+	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
+
+	error = xfs_trans_reserve_more(tp, dblocks, rtx);
+	if (error)
+		return error;
+
+	if (!XFS_IS_QUOTA_ON(mp) || xfs_is_quota_inode(&mp->m_sb, I_INO(ip)))
+		return 0;
+
+	if (tp->t_flags & XFS_TRANS_RESERVE)
+		force_quota = true;
+
+	error = xfs_trans_reserve_quota_nblks(tp, ip, dblocks, rblocks,
+			force_quota);
+	if (!error)
+		return 0;
+
+	/* Quota failed, give back the new reservation. */
+	xfs_add_fdblocks(mp, dblocks);
+	tp->t_blk_res -= dblocks;
+	xfs_add_frextents(mp, rtx);
+	tp->t_rtx_res -= rtx;
+	return error;
+}
+
+/*
+ * Allocate an transaction in preparation for inode creation by reserving quota
+ * against the given dquots.  Callers are not required to hold any inode locks.
+ */
+int
+xfs_trans_alloc_icreate(
+	struct xfs_mount	*mp,
+	struct xfs_trans_res	*resv,
+	struct xfs_dquot	*udqp,
+	struct xfs_dquot	*gdqp,
+	struct xfs_dquot	*pdqp,
+	unsigned int		dblocks,
+	struct xfs_trans	**tpp)
+{
+	struct xfs_trans	*tp;
+	bool			retried = false;
+	bool			flushed = false;
+	int			error;
+
+retry:
+	error = xfs_trans_alloc(mp, resv, dblocks, 0, 0, &tp);
+	if (error == -ENOSPC && !flushed) {
+		/*
+		 * Flush all delalloc blocks to reclaim space from speculative
+		 * preallocation.  This is similar to the quota retry below
+		 * but targets FS-wide ENOSPC.
+		 */
+		xfs_flush_inodes(mp);
+		flushed = true;
+		goto retry;
+	}
+	if (error)
+		return error;
+
+	error = xfs_trans_reserve_quota_icreate(tp, udqp, gdqp, pdqp, dblocks);
+	if ((error == -EDQUOT || error == -ENOSPC) && !retried) {
+		xfs_trans_cancel(tp);
+		xfs_blockgc_free_dquots(mp, udqp, gdqp, pdqp, 0);
+		retried = true;
+		goto retry;
+	}
+	if (error) {
+		xfs_trans_cancel(tp);
+		return error;
+	}
+
+	*tpp = tp;
+	return 0;
+}
+
+/*
+ * Allocate an transaction, lock and join the inode to it, and reserve quota
+ * in preparation for inode attribute changes that include uid, gid, or prid
+ * changes.
+ *
+ * The caller must ensure that the on-disk dquots attached to this inode have
+ * already been allocated and initialized.  The ILOCK will be dropped when the
+ * transaction is committed or cancelled.
+ */
+int
+xfs_trans_alloc_ichange(
+	struct xfs_inode	*ip,
+	struct xfs_dquot	*new_udqp,
+	struct xfs_dquot	*new_gdqp,
+	struct xfs_dquot	*new_pdqp,
+	bool			force,
+	struct xfs_trans	**tpp)
+{
+	struct xfs_trans	*tp;
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_dquot	*udqp;
+	struct xfs_dquot	*gdqp;
+	struct xfs_dquot	*pdqp;
+	bool			retried = false;
+	int			error;
+
+retry:
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
+	if (error)
+		return error;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+
+	if (xfs_is_metadir_inode(ip))
+		goto out;
+
+	error = xfs_qm_dqattach_locked(ip, false);
+	if (error) {
+		/* Caller should have allocated the dquots! */
+		ASSERT(error != -ENOENT);
+		goto out_cancel;
+	}
+
+	/*
+	 * For each quota type, skip quota reservations if the inode's dquots
+	 * now match the ones that came from the caller, or the caller didn't
+	 * pass one in.  The inode's dquots can change if we drop the ILOCK to
+	 * perform a blockgc scan, so we must preserve the caller's arguments.
+	 */
+	udqp = (new_udqp != ip->i_udquot) ? new_udqp : NULL;
+	gdqp = (new_gdqp != ip->i_gdquot) ? new_gdqp : NULL;
+	pdqp = (new_pdqp != ip->i_pdquot) ? new_pdqp : NULL;
+	if (udqp || gdqp || pdqp) {
+		xfs_filblks_t	dblocks, rblocks;
+		unsigned int	qflags = XFS_QMOPT_RES_REGBLKS;
+		bool		isrt = XFS_IS_REALTIME_INODE(ip);
+
+		if (force)
+			qflags |= XFS_QMOPT_FORCE_RES;
+
+		if (isrt) {
+			error = xfs_iread_extents(tp, ip, XFS_DATA_FORK);
+			if (error)
+				goto out_cancel;
+		}
+
+		xfs_inode_count_blocks(tp, ip, &dblocks, &rblocks);
+
+		if (isrt)
+			rblocks += ip->i_delayed_blks;
+		else
+			dblocks += ip->i_delayed_blks;
+
+		/*
+		 * Reserve enough quota to handle blocks on disk and reserved
+		 * for a delayed allocation.  We'll actually transfer the
+		 * delalloc reservation between dquots at chown time, even
+		 * though that part is only semi-transactional.
+		 */
+		error = xfs_trans_reserve_quota_bydquots(tp, mp, udqp, gdqp,
+				pdqp, dblocks, 1, qflags);
+		if ((error == -EDQUOT || error == -ENOSPC) && !retried) {
+			xfs_trans_cancel(tp);
+			xfs_blockgc_free_dquots(mp, udqp, gdqp, pdqp, 0);
+			retried = true;
+			goto retry;
+		}
+		if (error)
+			goto out_cancel;
+
+		/* Do the same for realtime. */
+		qflags = XFS_QMOPT_RES_RTBLKS | (qflags & XFS_QMOPT_FORCE_RES);
+		error = xfs_trans_reserve_quota_bydquots(tp, mp, udqp, gdqp,
+				pdqp, rblocks, 0, qflags);
+		if ((error == -EDQUOT || error == -ENOSPC) && !retried) {
+			xfs_trans_cancel(tp);
+			xfs_blockgc_free_dquots(mp, udqp, gdqp, pdqp, 0);
+			retried = true;
+			goto retry;
+		}
+		if (error)
+			goto out_cancel;
+	}
+
+out:
+	*tpp = tp;
+	return 0;
+
+out_cancel:
+	xfs_trans_cancel(tp);
+	return error;
+}
+
+/*
+ * Allocate an transaction, lock and join the directory and child inodes to it,
+ * and reserve quota for a directory update.  If there isn't sufficient space,
+ * @dblocks will be set to zero for a reservationless directory update and
+ * @nospace_error will be set to a negative errno describing the space
+ * constraint we hit.
+ *
+ * The caller must ensure that the on-disk dquots attached to this inode have
+ * already been allocated and initialized.  The ILOCKs will be dropped when the
+ * transaction is committed or cancelled.
+ *
+ * Caller is responsible for unlocking the inodes manually upon return
+ */
+int
+xfs_trans_alloc_dir(
+	struct xfs_inode	*dp,
+	struct xfs_trans_res	*resv,
+	struct xfs_inode	*ip,
+	unsigned int		*dblocks,
+	struct xfs_trans	**tpp,
+	int			*nospace_error)
+{
+	struct xfs_trans	*tp;
+	struct xfs_mount	*mp = ip->i_mount;
+	unsigned int		resblks;
+	bool			retried = false;
+	int			error;
+
+retry:
+	*nospace_error = 0;
+	resblks = *dblocks;
+	error = xfs_trans_alloc(mp, resv, resblks, 0, 0, &tp);
+	if (error == -ENOSPC) {
+		*nospace_error = error;
+		resblks = 0;
+		error = xfs_trans_alloc(mp, resv, resblks, 0, 0, &tp);
+	}
+	if (error)
+		return error;
+
+	xfs_lock_two_inodes(dp, XFS_ILOCK_EXCL, ip, XFS_ILOCK_EXCL);
+
+	xfs_trans_ijoin(tp, dp, 0);
+	xfs_trans_ijoin(tp, ip, 0);
+
+	error = xfs_qm_dqattach_locked(dp, false);
+	if (error) {
+		/* Caller should have allocated the dquots! */
+		ASSERT(error != -ENOENT);
+		goto out_cancel;
+	}
+
+	error = xfs_qm_dqattach_locked(ip, false);
+	if (error) {
+		/* Caller should have allocated the dquots! */
+		ASSERT(error != -ENOENT);
+		goto out_cancel;
+	}
+
+	if (resblks == 0)
+		goto done;
+
+	error = xfs_trans_reserve_quota_nblks(tp, dp, resblks, 0, false);
+	if (error == -EDQUOT || error == -ENOSPC) {
+		if (!retried) {
+			xfs_trans_cancel(tp);
+			xfs_iunlock(dp, XFS_ILOCK_EXCL);
+			if (dp != ip)
+				xfs_iunlock(ip, XFS_ILOCK_EXCL);
+			xfs_blockgc_free_quota(dp, 0);
+			retried = true;
+			goto retry;
+		}
+
+		*nospace_error = error;
+		resblks = 0;
+		error = 0;
+	}
+	if (error)
+		goto out_cancel;
+
+done:
+	*tpp = tp;
+	*dblocks = resblks;
+	return 0;
+
+out_cancel:
+	xfs_trans_cancel(tp);
+	xfs_iunlock(dp, XFS_ILOCK_EXCL);
+	if (dp != ip)
+		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+}