Adding upstream version 6.9.7.upstream/6.9.7

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 767 insertions, 0 deletions

diff --git a/fs/xfs/scrub/iscan.c b/fs/xfs/scrub/iscan.c
new file mode 100644
index 0000000000..ec3478bc50
--- /dev/null
+++ b/fs/xfs/scrub/iscan.c
@@ -0,0 +1,767 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2021-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_inode.h"
+#include "xfs_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_ag.h"
+#include "xfs_error.h"
+#include "xfs_bit.h"
+#include "xfs_icache.h"
+#include "scrub/scrub.h"
+#include "scrub/iscan.h"
+#include "scrub/common.h"
+#include "scrub/trace.h"
+
+/*
+ * Live File Scan
+ * ==============
+ *
+ * Live file scans walk every inode in a live filesystem.  This is more or
+ * less like a regular iwalk, except that when we're advancing the scan cursor,
+ * we must ensure that inodes cannot be added or deleted anywhere between the
+ * old cursor value and the new cursor value.  If we're advancing the cursor
+ * by one inode, the caller must hold that inode; if we're finding the next
+ * inode to scan, we must grab the AGI and hold it until we've updated the
+ * scan cursor.
+ *
+ * Callers are expected to use this code to scan all files in the filesystem to
+ * construct a new metadata index of some kind.  The scan races against other
+ * live updates, which means there must be a provision to update the new index
+ * when updates are made to inodes that already been scanned.  The iscan lock
+ * can be used in live update hook code to stop the scan and protect this data
+ * structure.
+ *
+ * To keep the new index up to date with other metadata updates being made to
+ * the live filesystem, it is assumed that the caller will add hooks as needed
+ * to be notified when a metadata update occurs.  The inode scanner must tell
+ * the hook code when an inode has been visited with xchk_iscan_mark_visit.
+ * Hook functions can use xchk_iscan_want_live_update to decide if the
+ * scanner's observations must be updated.
+ */
+
+/*
+ * If the inobt record @rec covers @iscan->skip_ino, mark the inode free so
+ * that the scan ignores that inode.
+ */
+STATIC void
+xchk_iscan_mask_skipino(
+	struct xchk_iscan	*iscan,
+	struct xfs_perag	*pag,
+	struct xfs_inobt_rec_incore	*rec,
+	xfs_agino_t		lastrecino)
+{
+	struct xfs_scrub	*sc = iscan->sc;
+	struct xfs_mount	*mp = sc->mp;
+	xfs_agnumber_t		skip_agno = XFS_INO_TO_AGNO(mp, iscan->skip_ino);
+	xfs_agnumber_t		skip_agino = XFS_INO_TO_AGINO(mp, iscan->skip_ino);
+
+	if (pag->pag_agno != skip_agno)
+		return;
+	if (skip_agino < rec->ir_startino)
+		return;
+	if (skip_agino > lastrecino)
+		return;
+
+	rec->ir_free |= xfs_inobt_maskn(skip_agino - rec->ir_startino, 1);
+}
+
+/*
+ * Set *cursor to the next allocated inode after whatever it's set to now.
+ * If there are no more inodes in this AG, cursor is set to NULLAGINO.
+ */
+STATIC int
+xchk_iscan_find_next(
+	struct xchk_iscan	*iscan,
+	struct xfs_buf		*agi_bp,
+	struct xfs_perag	*pag,
+	xfs_inofree_t		*allocmaskp,
+	xfs_agino_t		*cursor,
+	uint8_t			*nr_inodesp)
+{
+	struct xfs_scrub	*sc = iscan->sc;
+	struct xfs_inobt_rec_incore	rec;
+	struct xfs_btree_cur	*cur;
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_trans	*tp = sc->tp;
+	xfs_agnumber_t		agno = pag->pag_agno;
+	xfs_agino_t		lastino = NULLAGINO;
+	xfs_agino_t		first, last;
+	xfs_agino_t		agino = *cursor;
+	int			has_rec;
+	int			error;
+
+	/* If the cursor is beyond the end of this AG, move to the next one. */
+	xfs_agino_range(mp, agno, &first, &last);
+	if (agino > last) {
+		*cursor = NULLAGINO;
+		return 0;
+	}
+
+	/*
+	 * Look up the inode chunk for the current cursor position.  If there
+	 * is no chunk here, we want the next one.
+	 */
+	cur = xfs_inobt_init_cursor(pag, tp, agi_bp);
+	error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &has_rec);
+	if (!error && !has_rec)
+		error = xfs_btree_increment(cur, 0, &has_rec);
+	for (; !error; error = xfs_btree_increment(cur, 0, &has_rec)) {
+		xfs_inofree_t	allocmask;
+
+		/*
+		 * If we've run out of inobt records in this AG, move the
+		 * cursor on to the next AG and exit.  The caller can try
+		 * again with the next AG.
+		 */
+		if (!has_rec) {
+			*cursor = NULLAGINO;
+			break;
+		}
+
+		error = xfs_inobt_get_rec(cur, &rec, &has_rec);
+		if (error)
+			break;
+		if (!has_rec) {
+			error = -EFSCORRUPTED;
+			break;
+		}
+
+		/* Make sure that we always move forward. */
+		if (lastino != NULLAGINO &&
+		    XFS_IS_CORRUPT(mp, lastino >= rec.ir_startino)) {
+			error = -EFSCORRUPTED;
+			break;
+		}
+		lastino = rec.ir_startino + XFS_INODES_PER_CHUNK - 1;
+
+		/*
+		 * If this record only covers inodes that come before the
+		 * cursor, advance to the next record.
+		 */
+		if (rec.ir_startino + XFS_INODES_PER_CHUNK <= agino)
+			continue;
+
+		if (iscan->skip_ino)
+			xchk_iscan_mask_skipino(iscan, pag, &rec, lastino);
+
+		/*
+		 * If the incoming lookup put us in the middle of an inobt
+		 * record, mark it and the previous inodes "free" so that the
+		 * search for allocated inodes will start at the cursor.
+		 * We don't care about ir_freecount here.
+		 */
+		if (agino >= rec.ir_startino)
+			rec.ir_free |= xfs_inobt_maskn(0,
+						agino + 1 - rec.ir_startino);
+
+		/*
+		 * If there are allocated inodes in this chunk, find them
+		 * and update the scan cursor.
+		 */
+		allocmask = ~rec.ir_free;
+		if (hweight64(allocmask) > 0) {
+			int	next = xfs_lowbit64(allocmask);
+
+			ASSERT(next >= 0);
+			*cursor = rec.ir_startino + next;
+			*allocmaskp = allocmask >> next;
+			*nr_inodesp = XFS_INODES_PER_CHUNK - next;
+			break;
+		}
+	}
+
+	xfs_btree_del_cursor(cur, error);
+	return error;
+}
+
+/*
+ * Advance both the scan and the visited cursors.
+ *
+ * The inumber address space for a given filesystem is sparse, which means that
+ * the scan cursor can jump a long ways in a single iter() call.  There are no
+ * inodes in these sparse areas, so we must move the visited cursor forward at
+ * the same time so that the scan user can receive live updates for inodes that
+ * may get created once we release the AGI buffer.
+ */
+static inline void
+xchk_iscan_move_cursor(
+	struct xchk_iscan	*iscan,
+	xfs_agnumber_t		agno,
+	xfs_agino_t		agino)
+{
+	struct xfs_scrub	*sc = iscan->sc;
+	struct xfs_mount	*mp = sc->mp;
+	xfs_ino_t		cursor, visited;
+
+	BUILD_BUG_ON(XFS_MAXINUMBER == NULLFSINO);
+
+	/*
+	 * Special-case ino == 0 here so that we never set visited_ino to
+	 * NULLFSINO when wrapping around EOFS, for that will let through all
+	 * live updates.
+	 */
+	cursor = XFS_AGINO_TO_INO(mp, agno, agino);
+	if (cursor == 0)
+		visited = XFS_MAXINUMBER;
+	else
+		visited = cursor - 1;
+
+	mutex_lock(&iscan->lock);
+	iscan->cursor_ino = cursor;
+	iscan->__visited_ino = visited;
+	trace_xchk_iscan_move_cursor(iscan);
+	mutex_unlock(&iscan->lock);
+}
+
+/*
+ * Prepare to return agno/agino to the iscan caller by moving the lastino
+ * cursor to the previous inode.  Do this while we still hold the AGI so that
+ * no other threads can create or delete inodes in this AG.
+ */
+static inline void
+xchk_iscan_finish(
+	struct xchk_iscan	*iscan)
+{
+	mutex_lock(&iscan->lock);
+	iscan->cursor_ino = NULLFSINO;
+
+	/* All live updates will be applied from now on */
+	iscan->__visited_ino = NULLFSINO;
+
+	mutex_unlock(&iscan->lock);
+}
+
+/*
+ * Advance ino to the next inode that the inobt thinks is allocated, being
+ * careful to jump to the next AG if we've reached the right end of this AG's
+ * inode btree.  Advancing ino effectively means that we've pushed the inode
+ * scan forward, so set the iscan cursor to (ino - 1) so that our live update
+ * predicates will track inode allocations in that part of the inode number
+ * key space once we release the AGI buffer.
+ *
+ * Returns 1 if there's a new inode to examine, 0 if we've run out of inodes,
+ * -ECANCELED if the live scan aborted, or the usual negative errno.
+ */
+STATIC int
+xchk_iscan_advance(
+	struct xchk_iscan	*iscan,
+	struct xfs_perag	**pagp,
+	struct xfs_buf		**agi_bpp,
+	xfs_inofree_t		*allocmaskp,
+	uint8_t			*nr_inodesp)
+{
+	struct xfs_scrub	*sc = iscan->sc;
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_buf		*agi_bp;
+	struct xfs_perag	*pag;
+	xfs_agnumber_t		agno;
+	xfs_agino_t		agino;
+	int			ret;
+
+	ASSERT(iscan->cursor_ino >= iscan->__visited_ino);
+
+	do {
+		if (xchk_iscan_aborted(iscan))
+			return -ECANCELED;
+
+		agno = XFS_INO_TO_AGNO(mp, iscan->cursor_ino);
+		pag = xfs_perag_get(mp, agno);
+		if (!pag)
+			return -ECANCELED;
+
+		ret = xfs_ialloc_read_agi(pag, sc->tp, &agi_bp);
+		if (ret)
+			goto out_pag;
+
+		agino = XFS_INO_TO_AGINO(mp, iscan->cursor_ino);
+		ret = xchk_iscan_find_next(iscan, agi_bp, pag, allocmaskp,
+				&agino, nr_inodesp);
+		if (ret)
+			goto out_buf;
+
+		if (agino != NULLAGINO) {
+			/*
+			 * Found the next inode in this AG, so return it along
+			 * with the AGI buffer and the perag structure to
+			 * ensure it cannot go away.
+			 */
+			xchk_iscan_move_cursor(iscan, agno, agino);
+			*agi_bpp = agi_bp;
+			*pagp = pag;
+			return 1;
+		}
+
+		/*
+		 * Did not find any more inodes in this AG, move on to the next
+		 * AG.
+		 */
+		agno = (agno + 1) % mp->m_sb.sb_agcount;
+		xchk_iscan_move_cursor(iscan, agno, 0);
+		xfs_trans_brelse(sc->tp, agi_bp);
+		xfs_perag_put(pag);
+
+		trace_xchk_iscan_advance_ag(iscan);
+	} while (iscan->cursor_ino != iscan->scan_start_ino);
+
+	xchk_iscan_finish(iscan);
+	return 0;
+
+out_buf:
+	xfs_trans_brelse(sc->tp, agi_bp);
+out_pag:
+	xfs_perag_put(pag);
+	return ret;
+}
+
+/*
+ * Grabbing the inode failed, so we need to back up the scan and ask the caller
+ * to try to _advance the scan again.  Returns -EBUSY if we've run out of retry
+ * opportunities, -ECANCELED if the process has a fatal signal pending, or
+ * -EAGAIN if we should try again.
+ */
+STATIC int
+xchk_iscan_iget_retry(
+	struct xchk_iscan	*iscan,
+	bool			wait)
+{
+	ASSERT(iscan->cursor_ino == iscan->__visited_ino + 1);
+
+	if (!iscan->iget_timeout ||
+	    time_is_before_jiffies(iscan->__iget_deadline))
+		return -EBUSY;
+
+	if (wait) {
+		unsigned long	relax;
+
+		/*
+		 * Sleep for a period of time to let the rest of the system
+		 * catch up.  If we return early, someone sent a kill signal to
+		 * the calling process.
+		 */
+		relax = msecs_to_jiffies(iscan->iget_retry_delay);
+		trace_xchk_iscan_iget_retry_wait(iscan);
+
+		if (schedule_timeout_killable(relax) ||
+		    xchk_iscan_aborted(iscan))
+			return -ECANCELED;
+	}
+
+	iscan->cursor_ino--;
+	return -EAGAIN;
+}
+
+/*
+ * Grab an inode as part of an inode scan.  While scanning this inode, the
+ * caller must ensure that no other threads can modify the inode until a call
+ * to xchk_iscan_visit succeeds.
+ *
+ * Returns the number of incore inodes grabbed; -EAGAIN if the caller should
+ * call again xchk_iscan_advance; -EBUSY if we couldn't grab an inode;
+ * -ECANCELED if there's a fatal signal pending; or some other negative errno.
+ */
+STATIC int
+xchk_iscan_iget(
+	struct xchk_iscan	*iscan,
+	struct xfs_perag	*pag,
+	struct xfs_buf		*agi_bp,
+	xfs_inofree_t		allocmask,
+	uint8_t			nr_inodes)
+{
+	struct xfs_scrub	*sc = iscan->sc;
+	struct xfs_mount	*mp = sc->mp;
+	xfs_ino_t		ino = iscan->cursor_ino;
+	unsigned int		idx = 0;
+	unsigned int		i;
+	int			error;
+
+	ASSERT(iscan->__inodes[0] == NULL);
+
+	/* Fill the first slot in the inode array. */
+	error = xfs_iget(sc->mp, sc->tp, ino, XFS_IGET_NORETRY, 0,
+			&iscan->__inodes[idx]);
+
+	trace_xchk_iscan_iget(iscan, error);
+
+	if (error == -ENOENT || error == -EAGAIN) {
+		xfs_trans_brelse(sc->tp, agi_bp);
+		xfs_perag_put(pag);
+
+		/*
+		 * It's possible that this inode has lost all of its links but
+		 * hasn't yet been inactivated.  If we don't have a transaction
+		 * or it's not writable, flush the inodegc workers and wait.
+		 */
+		xfs_inodegc_flush(mp);
+		return xchk_iscan_iget_retry(iscan, true);
+	}
+
+	if (error == -EINVAL) {
+		xfs_trans_brelse(sc->tp, agi_bp);
+		xfs_perag_put(pag);
+
+		/*
+		 * We thought the inode was allocated, but the inode btree
+		 * lookup failed, which means that it was freed since the last
+		 * time we advanced the cursor.  Back up and try again.  This
+		 * should never happen since still hold the AGI buffer from the
+		 * inobt check, but we need to be careful about infinite loops.
+		 */
+		return xchk_iscan_iget_retry(iscan, false);
+	}
+
+	if (error) {
+		xfs_trans_brelse(sc->tp, agi_bp);
+		xfs_perag_put(pag);
+		return error;
+	}
+	idx++;
+	ino++;
+	allocmask >>= 1;
+
+	/*
+	 * Now that we've filled the first slot in __inodes, try to fill the
+	 * rest of the batch with consecutively ordered inodes.  to reduce the
+	 * number of _iter calls.  Make a bitmap of unallocated inodes from the
+	 * zeroes in the inuse bitmap; these inodes will not be scanned, but
+	 * the _want_live_update predicate will pass through all live updates.
+	 *
+	 * If we can't iget an allocated inode, stop and return what we have.
+	 */
+	mutex_lock(&iscan->lock);
+	iscan->__batch_ino = ino - 1;
+	iscan->__skipped_inomask = 0;
+	mutex_unlock(&iscan->lock);
+
+	for (i = 1; i < nr_inodes; i++, ino++, allocmask >>= 1) {
+		if (!(allocmask & 1)) {
+			ASSERT(!(iscan->__skipped_inomask & (1ULL << i)));
+
+			mutex_lock(&iscan->lock);
+			iscan->cursor_ino = ino;
+			iscan->__skipped_inomask |= (1ULL << i);
+			mutex_unlock(&iscan->lock);
+			continue;
+		}
+
+		ASSERT(iscan->__inodes[idx] == NULL);
+
+		error = xfs_iget(sc->mp, sc->tp, ino, XFS_IGET_NORETRY, 0,
+				&iscan->__inodes[idx]);
+		if (error)
+			break;
+
+		mutex_lock(&iscan->lock);
+		iscan->cursor_ino = ino;
+		mutex_unlock(&iscan->lock);
+		idx++;
+	}
+
+	trace_xchk_iscan_iget_batch(sc->mp, iscan, nr_inodes, idx);
+	xfs_trans_brelse(sc->tp, agi_bp);
+	xfs_perag_put(pag);
+	return idx;
+}
+
+/*
+ * Advance the visit cursor to reflect skipped inodes beyond whatever we
+ * scanned.
+ */
+STATIC void
+xchk_iscan_finish_batch(
+	struct xchk_iscan	*iscan)
+{
+	xfs_ino_t		highest_skipped;
+
+	mutex_lock(&iscan->lock);
+
+	if (iscan->__batch_ino != NULLFSINO) {
+		highest_skipped = iscan->__batch_ino +
+					xfs_highbit64(iscan->__skipped_inomask);
+		iscan->__visited_ino = max(iscan->__visited_ino,
+					   highest_skipped);
+
+		trace_xchk_iscan_skip(iscan);
+	}
+
+	iscan->__batch_ino = NULLFSINO;
+	iscan->__skipped_inomask = 0;
+
+	mutex_unlock(&iscan->lock);
+}
+
+/*
+ * Advance the inode scan cursor to the next allocated inode and return up to
+ * 64 consecutive allocated inodes starting with the cursor position.
+ */
+STATIC int
+xchk_iscan_iter_batch(
+	struct xchk_iscan	*iscan)
+{
+	struct xfs_scrub	*sc = iscan->sc;
+	int			ret;
+
+	xchk_iscan_finish_batch(iscan);
+
+	if (iscan->iget_timeout)
+		iscan->__iget_deadline = jiffies +
+					 msecs_to_jiffies(iscan->iget_timeout);
+
+	do {
+		struct xfs_buf	*agi_bp = NULL;
+		struct xfs_perag *pag = NULL;
+		xfs_inofree_t	allocmask = 0;
+		uint8_t		nr_inodes = 0;
+
+		ret = xchk_iscan_advance(iscan, &pag, &agi_bp, &allocmask,
+				&nr_inodes);
+		if (ret != 1)
+			return ret;
+
+		if (xchk_iscan_aborted(iscan)) {
+			xfs_trans_brelse(sc->tp, agi_bp);
+			xfs_perag_put(pag);
+			ret = -ECANCELED;
+			break;
+		}
+
+		ret = xchk_iscan_iget(iscan, pag, agi_bp, allocmask, nr_inodes);
+	} while (ret == -EAGAIN);
+
+	return ret;
+}
+
+/*
+ * Advance the inode scan cursor to the next allocated inode and return the
+ * incore inode structure associated with it.
+ *
+ * Returns 1 if there's a new inode to examine, 0 if we've run out of inodes,
+ * -ECANCELED if the live scan aborted, -EBUSY if the incore inode could not be
+ * grabbed, or the usual negative errno.
+ *
+ * If the function returns -EBUSY and the caller can handle skipping an inode,
+ * it may call this function again to continue the scan with the next allocated
+ * inode.
+ */
+int
+xchk_iscan_iter(
+	struct xchk_iscan	*iscan,
+	struct xfs_inode	**ipp)
+{
+	unsigned int		i;
+	int			error;
+
+	/* Find a cached inode, or go get another batch. */
+	for (i = 0; i < XFS_INODES_PER_CHUNK; i++) {
+		if (iscan->__inodes[i])
+			goto foundit;
+	}
+
+	error = xchk_iscan_iter_batch(iscan);
+	if (error <= 0)
+		return error;
+
+	ASSERT(iscan->__inodes[0] != NULL);
+	i = 0;
+
+foundit:
+	/* Give the caller our reference. */
+	*ipp = iscan->__inodes[i];
+	iscan->__inodes[i] = NULL;
+	return 1;
+}
+
+/* Clean up an xfs_iscan_iter call by dropping any inodes that we still hold. */
+void
+xchk_iscan_iter_finish(
+	struct xchk_iscan	*iscan)
+{
+	struct xfs_scrub	*sc = iscan->sc;
+	unsigned int		i;
+
+	for (i = 0; i < XFS_INODES_PER_CHUNK; i++) {
+		if (iscan->__inodes[i]) {
+			xchk_irele(sc, iscan->__inodes[i]);
+			iscan->__inodes[i] = NULL;
+		}
+	}
+}
+
+/* Mark this inode scan finished and release resources. */
+void
+xchk_iscan_teardown(
+	struct xchk_iscan	*iscan)
+{
+	xchk_iscan_iter_finish(iscan);
+	xchk_iscan_finish(iscan);
+	mutex_destroy(&iscan->lock);
+}
+
+/* Pick an AG from which to start a scan. */
+static inline xfs_ino_t
+xchk_iscan_rotor(
+	struct xfs_mount	*mp)
+{
+	static atomic_t		agi_rotor;
+	unsigned int		r = atomic_inc_return(&agi_rotor) - 1;
+
+	/*
+	 * Rotoring *backwards* through the AGs, so we add one here before
+	 * subtracting from the agcount to arrive at an AG number.
+	 */
+	r = (r % mp->m_sb.sb_agcount) + 1;
+
+	return XFS_AGINO_TO_INO(mp, mp->m_sb.sb_agcount - r, 0);
+}
+
+/*
+ * Set ourselves up to start an inode scan.  If the @iget_timeout and
+ * @iget_retry_delay parameters are set, the scan will try to iget each inode
+ * for @iget_timeout milliseconds.  If an iget call indicates that the inode is
+ * waiting to be inactivated, the CPU will relax for @iget_retry_delay
+ * milliseconds after pushing the inactivation workers.
+ */
+void
+xchk_iscan_start(
+	struct xfs_scrub	*sc,
+	unsigned int		iget_timeout,
+	unsigned int		iget_retry_delay,
+	struct xchk_iscan	*iscan)
+{
+	xfs_ino_t		start_ino;
+
+	start_ino = xchk_iscan_rotor(sc->mp);
+
+	iscan->__batch_ino = NULLFSINO;
+	iscan->__skipped_inomask = 0;
+
+	iscan->sc = sc;
+	clear_bit(XCHK_ISCAN_OPSTATE_ABORTED, &iscan->__opstate);
+	iscan->iget_timeout = iget_timeout;
+	iscan->iget_retry_delay = iget_retry_delay;
+	iscan->__visited_ino = start_ino;
+	iscan->cursor_ino = start_ino;
+	iscan->scan_start_ino = start_ino;
+	mutex_init(&iscan->lock);
+	memset(iscan->__inodes, 0, sizeof(iscan->__inodes));
+
+	trace_xchk_iscan_start(iscan, start_ino);
+}
+
+/*
+ * Mark this inode as having been visited.  Callers must hold a sufficiently
+ * exclusive lock on the inode to prevent concurrent modifications.
+ */
+void
+xchk_iscan_mark_visited(
+	struct xchk_iscan	*iscan,
+	struct xfs_inode	*ip)
+{
+	mutex_lock(&iscan->lock);
+	iscan->__visited_ino = ip->i_ino;
+	trace_xchk_iscan_visit(iscan);
+	mutex_unlock(&iscan->lock);
+}
+
+/*
+ * Did we skip this inode because it wasn't allocated when we loaded the batch?
+ * If so, it is newly allocated and will not be scanned.  All live updates to
+ * this inode must be passed to the caller to maintain scan correctness.
+ */
+static inline bool
+xchk_iscan_skipped(
+	const struct xchk_iscan	*iscan,
+	xfs_ino_t		ino)
+{
+	if (iscan->__batch_ino == NULLFSINO)
+		return false;
+	if (ino < iscan->__batch_ino)
+		return false;
+	if (ino >= iscan->__batch_ino + XFS_INODES_PER_CHUNK)
+		return false;
+
+	return iscan->__skipped_inomask & (1ULL << (ino - iscan->__batch_ino));
+}
+
+/*
+ * Do we need a live update for this inode?  This is true if the scanner thread
+ * has visited this inode and the scan hasn't been aborted due to errors.
+ * Callers must hold a sufficiently exclusive lock on the inode to prevent
+ * scanners from reading any inode metadata.
+ */
+bool
+xchk_iscan_want_live_update(
+	struct xchk_iscan	*iscan,
+	xfs_ino_t		ino)
+{
+	bool			ret = false;
+
+	if (xchk_iscan_aborted(iscan))
+		return false;
+
+	mutex_lock(&iscan->lock);
+
+	trace_xchk_iscan_want_live_update(iscan, ino);
+
+	/* Scan is finished, caller should receive all updates. */
+	if (iscan->__visited_ino == NULLFSINO) {
+		ret = true;
+		goto unlock;
+	}
+
+	/*
+	 * No inodes have been visited yet, so the visited cursor points at the
+	 * start of the scan range.  The caller should not receive any updates.
+	 */
+	if (iscan->scan_start_ino == iscan->__visited_ino) {
+		ret = false;
+		goto unlock;
+	}
+
+	/*
+	 * This inode was not allocated at the time of the iscan batch.
+	 * The caller should receive all updates.
+	 */
+	if (xchk_iscan_skipped(iscan, ino)) {
+		ret = true;
+		goto unlock;
+	}
+
+	/*
+	 * The visited cursor hasn't yet wrapped around the end of the FS.  If
+	 * @ino is inside the starred range, the caller should receive updates:
+	 *
+	 * 0 ------------ S ************ V ------------ EOFS
+	 */
+	if (iscan->scan_start_ino <= iscan->__visited_ino) {
+		if (ino >= iscan->scan_start_ino &&
+		    ino <= iscan->__visited_ino)
+			ret = true;
+
+		goto unlock;
+	}
+
+	/*
+	 * The visited cursor wrapped around the end of the FS.  If @ino is
+	 * inside the starred range, the caller should receive updates:
+	 *
+	 * 0 ************ V ------------ S ************ EOFS
+	 */
+	if (ino >= iscan->scan_start_ino || ino <= iscan->__visited_ino)
+		ret = true;
+
+unlock:
+	mutex_unlock(&iscan->lock);
+	return ret;
+}