1 files changed, 144 insertions, 0 deletions
diff --git a/fs/xfs/scrub/nlinks_repair.c b/fs/xfs/scrub/nlinks_repair.c
new file mode 100644
index 000000000000..81628172059e
--- /dev/null
+++ b/fs/xfs/scrub/nlinks_repair.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2021 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_icache.h"
+#include "xfs_bmap_util.h"
+#include "xfs_iwalk.h"
+#include "xfs_ialloc.h"
+#include "xfs_sb.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/repair.h"
+#include "scrub/array.h"
+#include "scrub/nlinks.h"
+#include "scrub/trace.h"
+
+/*
+ * Live Inode Link Count Repair
+ * ============================
+ *
+ * Use the live inode link count information that we collected to replace the
+ * nlink values of the incore inodes.  A scrub->repair cycle should have left
+ * the live data and hooks active, so this is safe so long as we make sure the
+ * inode is locked.
+ */
+
+/* Commit new counters to an inode. */
+static int
+xrep_nlinks_commit_inode(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_ino_t		ino,
+	void			*data)
+{
+	struct xchk_nlinks	*xnc = data;
+	struct xfs_inode	*ip = NULL;
+	xfs_nlink_t		live_nlink;
+	int			error;
+
+	error = xfs_iget(mp, tp, ino, XFS_IGET_UNTRUSTED | XFS_IGET_UNLINKED,
+			XFS_ILOCK_EXCL, &ip);
+	if (error == -ENOENT || error == -EINVAL) {
+		/* Inode wasn't found, so we'll check for zero nlink. */
+		error = 0;
+	}
+	if (error)
+		return error;
+
+	mutex_lock(&xnc->lock);
+	if (xnc->hook_dead) {
+		error = -ECANCELED;
+		goto out_unlock;
+	}
+	error = xchk_nlinks_get_shadow_count(xnc, ino, &live_nlink);
+	if (error)
+		goto out_unlock;
+
+	if (ip == NULL) {
+		/*
+		 * We couldn't get the inode, so the link count had better be
+		 * zero!  This means we cannot fix the filesystem.
+		 */
+		if (live_nlink != 0) {
+			trace_xrep_nlinks_unfixable_inode(mp, ino, 0,
+					live_nlink);
+			error = -EFSCORRUPTED;
+		}
+		goto out_unlock;
+	}
+
+	/* Commit the new link count, if necessary. */
+	if (live_nlink != VFS_I(ip)->i_nlink) {
+		trace_xrep_nlinks_commit_inode(mp, ino, VFS_I(ip)->i_nlink,
+				live_nlink);
+
+		xfs_trans_ijoin(tp, ip, 0);
+		set_nlink(VFS_I(ip), live_nlink);
+		xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+		error = xrep_roll_trans(xnc->sc);
+	}
+
+out_unlock:
+	if (error)
+		xnc->hook_dead = true;
+	mutex_unlock(&xnc->lock);
+	if (ip) {
+		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+		xchk_irele(xnc->sc, ip);
+	}
+	return error;
+}
+
+/* Commit the new inode link counters. */
+int
+xrep_nlinks(
+	struct xfs_scrub	*sc)
+{
+	struct xchk_nlinks	*xnc = sc->buf;
+	uint64_t		nr = 0;
+	xfs_nlink_t		nlink;
+	int			error;
+
+	/* Update the link count of every inode that the inobt knows about. */
+	error = xfs_iwalk(sc->mp, sc->tp, 0, XFS_IWALK_METADIR,
+			xrep_nlinks_commit_inode, 0, xnc);
+	if (error)
+		return error;
+
+	/*
+	 * Make a second pass to find inodes for which we have positive link
+	 * count but don't seem to exist on disk.  We cannot resuscitate dead
+	 * inodes, but we can at least signal failure.
+	 */
+	mutex_lock(&xnc->lock);
+	while (!(error = xfbma_iter_get(xnc->nlinks, &nr, &nlink))) {
+		mutex_unlock(&xnc->lock);
+
+		if (xchk_should_terminate(xnc->sc, &error))
+			return error;
+
+		error = xrep_nlinks_commit_inode(sc->mp, sc->tp, nr - 1, xnc);
+		if (error)
+			return error;
+
+		mutex_lock(&xnc->lock);
+	}
+	mutex_unlock(&xnc->lock);
+
+	/* ENODATA means we hit the end of the array. */
+	if (error == -ENODATA)
+		return 0;
+
+	return error;
+}