diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
index c5a6c47d3df2..699092195f41 100644
--- a/fs/xfs/scrub/common.c
+++ b/fs/xfs/scrub/common.c
@@ -1302,6 +1302,9 @@ xchk_fsgates_enable(
 	if (scrub_fsgates & XCHK_FSGATES_QUOTA)
 		xfs_dqtrx_hook_enable();
 
+	if (scrub_fsgates & XCHK_FSGATES_DIRENTS)
+		xfs_dir_hook_enable();
+
 	sc->flags |= scrub_fsgates;
 }
 
diff --git a/fs/xfs/scrub/nlinks.c b/fs/xfs/scrub/nlinks.c
index c899a50a83da..341ab737f9c5 100644
--- a/fs/xfs/scrub/nlinks.c
+++ b/fs/xfs/scrub/nlinks.c
@@ -43,8 +43,7 @@ int
 xchk_setup_nlinks(
 	struct xfs_scrub	*sc)
 {
-	/* Not ready for general consumption yet. */
-	return -EOPNOTSUPP;
+	xchk_fsgates_enable(sc, XCHK_FSGATES_DIRENTS);
 
 	sc->buf = kzalloc(sizeof(struct xchk_nlink_ctrs), XCHK_GFP_FLAGS);
 	if (!sc->buf)
@@ -63,6 +62,21 @@ xchk_setup_nlinks(
  * must be taken with certain errno values (i.e. EFSBADCRC, EFSCORRUPTED,
  * ECANCELED) that are absorbed into a scrub state flag update by
  * xchk_*_process_error.
+ *
+ * Because we are scanning a live filesystem, it's possible that another thread
+ * will try to update the link counts for an inode that we've already scanned.
+ * This will cause our counts to be incorrect.  Therefore, we hook all
+ * directory entry updates because that is when link count updates occur.  By
+ * shadowing transaction updates in this manner, live nlink check can ensure by
+ * locking the inode and the shadow structure that its own copies are not out
+ * of date.  Because the hook code runs in a different process context from the
+ * scrub code and the scrub state flags are not accessed atomically, failures
+ * in the hook code must abort the iscan and the scrubber must notice the
+ * aborted scan and set the incomplete flag.
+ *
+ * Note that we use jump labels and srcu notifier hooks to minimize the
+ * overhead when live nlinks is /not/ running.  Locking order for nlink
+ * observations is inode ILOCK -> iscan_lock/xchk_nlink_ctrs lock.
  */
 
 /*
@@ -120,6 +134,63 @@ xchk_nlinks_update_incore(
 	return error;
 }
 
+/*
+ * Apply a link count change from the regular filesystem into our shadow link
+ * count structure based on a directory update in progress.
+ */
+STATIC int
+xchk_nlinks_live_update(
+	struct notifier_block		*nb,
+	unsigned long			action,
+	void				*data)
+{
+	struct xfs_dir_update_params	*p = data;
+	struct xchk_nlink_ctrs		*xnc;
+	int				error;
+
+	xnc = container_of(nb, struct xchk_nlink_ctrs, dhook.dirent_hook.nb);
+
+	trace_xchk_nlinks_live_update(xnc->sc->mp, p->dp, action, p->ip->i_ino,
+			p->delta, p->name->name, p->name->len);
+
+	/*
+	 * If we've already scanned @dp, update the number of parents that link
+	 * to @ip.  If @ip is a subdirectory, update the number of child links
+	 * going out of @dp.
+	 */
+	if (xchk_iscan_want_live_update(&xnc->collect_iscan, p->dp->i_ino)) {
+		mutex_lock(&xnc->lock);
+		error = xchk_nlinks_update_incore(xnc, p->ip->i_ino, p->delta,
+				0, 0);
+		if (!error && S_ISDIR(VFS_IC(p->ip)->i_mode))
+			error = xchk_nlinks_update_incore(xnc, p->dp->i_ino, 0,
+					0, p->delta);
+		mutex_unlock(&xnc->lock);
+		if (error)
+			goto out_abort;
+	}
+
+	/*
+	 * If @ip is a subdirectory and we've already scanned it, update the
+	 * number of backrefs pointing to @dp.
+	 */
+	if (S_ISDIR(VFS_IC(p->ip)->i_mode) &&
+	    xchk_iscan_want_live_update(&xnc->collect_iscan, p->ip->i_ino)) {
+		mutex_lock(&xnc->lock);
+		error = xchk_nlinks_update_incore(xnc, p->dp->i_ino, 0,
+				p->delta, 0);
+		mutex_unlock(&xnc->lock);
+		if (error)
+			goto out_abort;
+	}
+
+	return NOTIFY_DONE;
+
+out_abort:
+	xchk_iscan_abort(&xnc->collect_iscan);
+	return NOTIFY_DONE;
+}
+
 /* Bump the observed link count for the inode referenced by this entry. */
 STATIC int
 xchk_nlinks_collect_dirent(
@@ -747,6 +818,11 @@ xchk_nlinks_teardown_scan(
 {
 	struct xchk_nlink_ctrs	*xnc = priv;
 
+	/* Discourage any hook functions that might be running. */
+	xchk_iscan_abort(&xnc->collect_iscan);
+
+	xfs_dir_hook_del(xnc->sc->mp, &xnc->dhook);
+
 	xfarray_destroy(xnc->nlinks);
 	xnc->nlinks = NULL;
 
@@ -793,6 +869,19 @@ xchk_nlinks_setup_scan(
 	if (error)
 		goto out_teardown;
 
+	/*
+	 * Hook into the directory entry code so that we can capture updates to
+	 * file link counts.  The hook only triggers for inodes that were
+	 * already scanned, and the scanner thread takes each inode's ILOCK,
+	 * which means that any in-progress inode updates will finish before we
+	 * can scan the inode.
+	 */
+	ASSERT(sc->flags & XCHK_FSGATES_DIRENTS);
+	xfs_dir_hook_setup(&xnc->dhook, xchk_nlinks_live_update);
+	error = xfs_dir_hook_add(mp, &xnc->dhook);
+	if (error)
+		goto out_teardown;
+
 	/* Use deferred cleanup to pass the inode link count data to repair. */
 	sc->buf_cleanup = xchk_nlinks_teardown_scan;
 	return 0;
diff --git a/fs/xfs/scrub/nlinks.h b/fs/xfs/scrub/nlinks.h
index 69a3460c5e52..ea6408e1c183 100644
--- a/fs/xfs/scrub/nlinks.h
+++ b/fs/xfs/scrub/nlinks.h
@@ -22,6 +22,12 @@ struct xchk_nlink_ctrs {
 	 */
 	struct xchk_iscan	collect_iscan;
 	struct xchk_iscan	compare_iscan;
+
+	/*
+	 * Hook into directory updates so that we can receive live updates
+	 * from other writer threads.
+	 */
+	struct xfs_dir_hook	dhook;
 };
 
 /*
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 8c60774d5f34..883c47b6c686 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -160,6 +160,9 @@ xchk_fsgates_disable(
 	if (sc->flags & XCHK_FSGATES_QUOTA)
 		xfs_dqtrx_hook_disable();
 
+	if (sc->flags & XCHK_FSGATES_DIRENTS)
+		xfs_dir_hook_disable();
+
 	sc->flags &= ~XCHK_FSGATES_ALL;
 }
 
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index de6b45f99dd5..f99a3c21d02e 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -122,6 +122,7 @@ struct xfs_scrub {
 #define XCHK_FSGATES_DRAIN	(1U << 2)  /* defer ops draining enabled */
 #define XCHK_NEED_DRAIN		(1U << 3)  /* scrub needs to drain defer ops */
 #define XCHK_FSGATES_QUOTA	(1U << 4)  /* quota live update enabled */
+#define XCHK_FSGATES_DIRENTS	(1U << 5)  /* directory live update enabled */
 #define XREP_RESET_PERAG_RESV	(1U << 30) /* must reset AG space reservation */
 #define XREP_ALREADY_FIXED	(1U << 31) /* checking our repair work */
 
@@ -132,7 +133,8 @@ struct xfs_scrub {
  * must be enabled during scrub setup and can only be torn down afterwards.
  */
 #define XCHK_FSGATES_ALL	(XCHK_FSGATES_DRAIN | \
-				 XCHK_FSGATES_QUOTA)
+				 XCHK_FSGATES_QUOTA | \
+				 XCHK_FSGATES_DIRENTS)
 
 /* Metadata scrubbers */
 int xchk_tester(struct xfs_scrub *sc);
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index 0deea8f18a30..9512170ea9a7 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -116,6 +116,7 @@ TRACE_DEFINE_ENUM(XFS_SCRUB_TYPE_NLINKS);
 	{ XCHK_FSGATES_DRAIN,			"fsgates_drain" }, \
 	{ XCHK_NEED_DRAIN,			"need_drain" }, \
 	{ XCHK_FSGATES_QUOTA,			"fsgates_quota" }, \
+	{ XCHK_FSGATES_DIRENTS,			"fsgates_dirents" }, \
 	{ XREP_RESET_PERAG_RESV,		"reset_perag_resv" }, \
 	{ XREP_ALREADY_FIXED,			"already_fixed" }
 
@@ -1363,6 +1364,38 @@ TRACE_EVENT(xchk_nlinks_collect_metafile,
 		  __entry->ino)
 );
 
+TRACE_EVENT(xchk_nlinks_live_update,
+	TP_PROTO(struct xfs_mount *mp, const struct xfs_inode *dp,
+		 int action, xfs_ino_t ino, int delta,
+		 const char *name, unsigned int namelen),
+	TP_ARGS(mp, dp, action, ino, delta, name, namelen),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(xfs_ino_t, dir)
+		__field(int, action)
+		__field(xfs_ino_t, ino)
+		__field(int, delta)
+		__field(unsigned int, namelen)
+		__dynamic_array(char, name, namelen)
+	),
+	TP_fast_assign(
+		__entry->dev = mp->m_super->s_dev;
+		__entry->dir = dp ? dp->i_ino : NULLFSINO;
+		__entry->action = action;
+		__entry->ino = ino;
+		__entry->delta = delta;
+		__entry->namelen = namelen;
+		memcpy(__get_str(name), name, namelen);
+	),
+	TP_printk("dev %d:%d dir 0x%llx ino 0x%llx nlink_delta %d name '%.*s'",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->dir,
+		  __entry->ino,
+		  __entry->delta,
+		  __entry->namelen,
+		  __get_str(name))
+);
+
 TRACE_EVENT(xchk_nlinks_check_zero,
 	TP_PROTO(struct xfs_mount *mp, xfs_ino_t ino,
 		 const struct xchk_nlink *live),
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index d6635d219527..e8845287debd 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -925,6 +925,81 @@ xfs_bumplink(
 	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 }
 
+#ifdef CONFIG_XFS_LIVE_HOOKS
+/*
+ * Use a static key here to reduce the overhead of directory live update hooks.
+ * If the compiler supports jump labels, the static branch will be replaced by
+ * a nop sled when there are no hook users.  Online fsck is currently the only
+ * caller, so this is a reasonable tradeoff.
+ *
+ * Note: Patching the kernel code requires taking the cpu hotplug lock.  Other
+ * parts of the kernel allocate memory with that lock held, which means that
+ * XFS callers cannot hold any locks that might be used by memory reclaim or
+ * writeback when calling the static_branch_{inc,dec} functions.
+ */
+DEFINE_STATIC_XFS_HOOK_SWITCH(xfs_dir_hooks_switch);
+
+void
+xfs_dir_hook_disable(void)
+{
+	xfs_hooks_switch_off(&xfs_dir_hooks_switch);
+}
+
+void
+xfs_dir_hook_enable(void)
+{
+	xfs_hooks_switch_on(&xfs_dir_hooks_switch);
+}
+
+/* Call hooks for a directory update relating to a child dirent update. */
+inline void
+xfs_dir_update_hook(
+	struct xfs_inode		*dp,
+	struct xfs_inode		*ip,
+	int				delta,
+	const struct xfs_name		*name)
+{
+	if (xfs_hooks_switched_on(&xfs_dir_hooks_switch)) {
+		struct xfs_dir_update_params	p = {
+			.dp		= dp,
+			.ip		= ip,
+			.delta		= delta,
+			.name		= name,
+		};
+		struct xfs_mount	*mp = ip->i_mount;
+
+		xfs_hooks_call(&mp->m_dir_update_hooks, 0, &p);
+	}
+}
+
+/* Call the specified function during a directory update. */
+int
+xfs_dir_hook_add(
+	struct xfs_mount	*mp,
+	struct xfs_dir_hook	*hook)
+{
+	return xfs_hooks_add(&mp->m_dir_update_hooks, &hook->dirent_hook);
+}
+
+/* Stop calling the specified function during a directory update. */
+void
+xfs_dir_hook_del(
+	struct xfs_mount	*mp,
+	struct xfs_dir_hook	*hook)
+{
+	xfs_hooks_del(&mp->m_dir_update_hooks, &hook->dirent_hook);
+}
+
+/* Configure directory update hook functions. */
+void
+xfs_dir_hook_setup(
+	struct xfs_dir_hook	*hook,
+	notifier_fn_t		mod_fn)
+{
+	xfs_hook_setup(&hook->dirent_hook, mod_fn);
+}
+#endif /* CONFIG_XFS_LIVE_HOOKS */
+
 int
 xfs_create(
 	struct mnt_idmap	*idmap,
@@ -1035,6 +1110,12 @@ xfs_create(
 		xfs_bumplink(tp, dp);
 	}
 
+	/*
+	 * Create ip with a reference from dp, and add '.' and '..' references
+	 * if it's a directory.
+	 */
+	xfs_dir_update_hook(dp, ip, 1, name);
+
 	/*
 	 * If this is a synchronous mount, make sure that the
 	 * create transaction goes to disk before returning to
@@ -1249,6 +1330,7 @@ xfs_link(
 	xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);
 
 	xfs_bumplink(tp, sip);
+	xfs_dir_update_hook(tdp, sip, 1, target_name);
 
 	/*
 	 * If this is a synchronous mount, make sure that the
@@ -2562,6 +2644,12 @@ xfs_remove(
 		goto out_trans_cancel;
 	}
 
+	/*
+	 * Drop the link from dp to ip, and if ip was a directory, remove the
+	 * '.' and '..' references since we freed the directory.
+	 */
+	xfs_dir_update_hook(dp, ip, -1, name);
+
 	/*
 	 * If this is a synchronous mount, make sure that the
 	 * remove transaction goes to disk before returning to
@@ -2752,6 +2840,20 @@ xfs_cross_rename(
 	}
 	xfs_trans_ichgtime(tp, dp1, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 	xfs_trans_log_inode(tp, dp1, XFS_ILOG_CORE);
+
+	/*
+	 * Inform our hook clients that we've finished an exchange operation as
+	 * follows: removed the source and target files from their directories;
+	 * added the target to the source directory; and added the source to
+	 * the target directory.  All inodes are locked, so it's ok to model a
+	 * rename this way so long as we say we deleted entries before we add
+	 * new ones.
+	 */
+	xfs_dir_update_hook(dp1, ip1, -1, name1);
+	xfs_dir_update_hook(dp2, ip2, -1, name2);
+	xfs_dir_update_hook(dp1, ip2, 1, name1);
+	xfs_dir_update_hook(dp2, ip1, 1, name2);
+
 	return xfs_finish_rename(tp);
 
 out_trans_abort:
@@ -3135,6 +3237,21 @@ retry:
 	if (new_parent)
 		xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
 
+	/*
+	 * Inform our hook clients that we've finished a rename operation as
+	 * follows: removed the source and target files from their directories;
+	 * that we've added the source to the target directory; and finally
+	 * that we've added the whiteout, if there was one.  All inodes are
+	 * locked, so it's ok to model a rename this way so long as we say we
+	 * deleted entries before we add new ones.
+	 */
+	if (target_ip)
+		xfs_dir_update_hook(target_dp, target_ip, -1, target_name);
+	xfs_dir_update_hook(src_dp, src_ip, -1, src_name);
+	xfs_dir_update_hook(target_dp, src_ip, 1, target_name);
+	if (wip)
+		xfs_dir_update_hook(src_dp, wip, 1, src_name);
+
 	error = xfs_finish_rename(tp);
 	if (wip)
 		xfs_irele(wip);
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 7bbdc7009e7d..ab46ffb3ac19 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -171,6 +171,12 @@ static inline struct inode *VFS_I(struct xfs_inode *ip)
 	return &ip->i_vnode;
 }
 
+/* convert from const xfs inode to const vfs inode */
+static inline const struct inode *VFS_IC(const struct xfs_inode *ip)
+{
+	return &ip->i_vnode;
+}
+
 /*
  * For regular files we only update the on-disk filesize when actually
  * writing data back to disk.  Until then only the copy in the VFS inode
@@ -626,4 +632,29 @@ bool xfs_ifork_zapped(const struct xfs_inode *ip, int whichfork);
 void xfs_inode_count_blocks(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_filblks_t *dblocks, xfs_filblks_t *rblocks);
 
+struct xfs_dir_update_params {
+	const struct xfs_inode	*dp;
+	const struct xfs_inode	*ip;
+	const struct xfs_name	*name;
+	int			delta;
+};
+
+#ifdef CONFIG_XFS_LIVE_HOOKS
+void xfs_dir_update_hook(struct xfs_inode *dp, struct xfs_inode *ip,
+		int delta, const struct xfs_name *name);
+
+struct xfs_dir_hook {
+	struct xfs_hook		dirent_hook;
+};
+
+void xfs_dir_hook_disable(void);
+void xfs_dir_hook_enable(void);
+
+int xfs_dir_hook_add(struct xfs_mount *mp, struct xfs_dir_hook *hook);
+void xfs_dir_hook_del(struct xfs_mount *mp, struct xfs_dir_hook *hook);
+void xfs_dir_hook_setup(struct xfs_dir_hook *hook, notifier_fn_t mod_fn);
+#else
+# define xfs_dir_update_hook(dp, ip, delta, name)	((void)0)
+#endif /* CONFIG_XFS_LIVE_HOOKS */
+
 #endif	/* __XFS_INODE_H__ */
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 503fe3c7edbf..e86dfe67894f 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -252,6 +252,9 @@ typedef struct xfs_mount {
 
 	/* cpus that have inodes queued for inactivation */
 	struct cpumask		m_inodegc_cpumask;
+
+	/* Hook to feed dirent updates to an active online repair. */
+	struct xfs_hooks	m_dir_update_hooks;
 } xfs_mount_t;
 
 #define M_IGEO(mp)		(&(mp)->m_ino_geo)
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index b31652fa7004..74e87ed5eee1 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -2011,6 +2011,8 @@ static int xfs_init_fs_context(
 	mp->m_logbsize = -1;
 	mp->m_allocsize_log = 16; /* 64k */
 
+	xfs_hooks_init(&mp->m_dir_update_hooks);
+
 	fc->s_fs_info = mp;
 	fc->ops = &xfs_context_ops;
 
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
index c2dc8c501bdc..e73692fbe179 100644
--- a/fs/xfs/xfs_symlink.c
+++ b/fs/xfs/xfs_symlink.c
@@ -322,6 +322,7 @@ xfs_symlink(
 		goto out_trans_cancel;
 	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
+	xfs_dir_update_hook(dp, ip, 1, link_name);
 
 	/*
 	 * If this is a synchronous mount, make sure that the