[PATCH 7/9] xfs: fix allocated inodes that show up in the unlinked list

From: Darrick J. Wong <[email protected]>

If an allocated inode shows up in the unlinked list, we need to get it
completely off the list.  Set the corrected next/prev pointers such that
the inode will not look like it should be on an unlinked list at all.

Cc: <[email protected]> # v6.10
Fixes: ab97f4b1c03075 ("xfs: repair AGI unlinked inode bucket lists")
Signed-off-by: "Darrick J. Wong" <[email protected]>
---
 fs/xfs/scrub/trace.h           |    1 +
 fs/xfs/scrub/agheader_repair.c |   57 +++++++++++++++++++++++++++++++++++-----
 2 files changed, 51 insertions(+), 7 deletions(-)


diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index d5d39d82749e5c..00fbe1b9c2354f 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -3542,6 +3542,7 @@ DEFINE_REPAIR_IUNLINK_RESOLVE_EVENT(xrep_iunlink_resolve_uncached);
 DEFINE_REPAIR_IUNLINK_RESOLVE_EVENT(xrep_iunlink_resolve_wronglist);
 DEFINE_REPAIR_IUNLINK_RESOLVE_EVENT(xrep_iunlink_resolve_nolist);
 DEFINE_REPAIR_IUNLINK_RESOLVE_EVENT(xrep_iunlink_resolve_ok);
+DEFINE_REPAIR_IUNLINK_RESOLVE_EVENT(xrep_iunlink_resolve_allocated);
 
 TRACE_EVENT(xrep_iunlink_relink_next,
 	TP_PROTO(struct xfs_inode *ip, xfs_agino_t next_agino),
diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index 8514d2d7e3cea3..edd406a97b7ce9 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -979,6 +979,13 @@ xrep_agi_calc_from_btrees(
 	return error;
 }
 
+/*
+ * Magic value that means "not unlinked" because xfarrays don't support storing
+ * totally zeroed elements.  There can't be a cluster that starts in daddr 0 so
+ * there can't be an inode #1 either.
+ */
+#define LINKED_AGINO	(0x1)
+
 /*
  * Record a forwards unlinked chain pointer from agino -> next_agino in our
  * staging information.
@@ -1362,6 +1369,29 @@ xrep_iunlink_resolve_bucket(
 			break;
 		}
 
+		if (VFS_I(ip)->i_nlink != 0) {
+			/*
+			 * Inode is allocated!  Blow out both unlinked list
+			 * pointers, advance the list, and pretend we didn't
+			 * see this inode.
+			 */
+			trace_xrep_iunlink_resolve_allocated(sc->sa.pag,
+					bucket, prev_agino, next_agino);
+
+			error = xrep_iunlink_store_next(ragi, next_agino,
+					NULLAGINO);
+			if (error)
+				return error;
+
+			error = xrep_iunlink_store_prev(ragi, next_agino,
+					LINKED_AGINO);
+			if (error)
+				return error;
+
+			next_agino = ip->i_next_unlinked;
+			continue;
+		}
+
 		if (next_agino % XFS_AGI_UNLINKED_BUCKETS != bucket) {
 			/*
 			 * Inode is in the wrong bucket.  Advance the list,
@@ -1540,6 +1570,24 @@ xrep_iunlink_rebuild_buckets(
 			xrep_iunlink_add_lost_inodes, ragi);
 }
 
+static inline void
+set_inode_prev_unlinked(
+	struct xfs_inode	*ip,
+	xfs_agino_t		prev_agino)
+{
+	/*
+	 * Magic value that means "not unlinked" because xfarrays don't support
+	 * storing totally zeroed elements.
+	 */
+	if (prev_agino == LINKED_AGINO)
+		prev_agino = 0;
+
+	if (ip->i_prev_unlinked != prev_agino) {
+		trace_xrep_iunlink_relink_prev(ip, prev_agino);
+		ip->i_prev_unlinked = prev_agino;
+	}
+}
+
 /* Update i_next_iunlinked for the inode @agino. */
 STATIC int
 xrep_iunlink_relink_next(
@@ -1573,8 +1621,7 @@ xrep_iunlink_relink_next(
 		if (error)
 			goto out_rele;
 
-		trace_xrep_iunlink_relink_prev(ip, prev_agino);
-		ip->i_prev_unlinked = prev_agino;
+		set_inode_prev_unlinked(ip, prev_agino);
 	}
 
 	/* Update the forward pointer. */
@@ -1641,11 +1688,7 @@ xrep_iunlink_relink_prev(
 		ip->i_next_unlinked = next_agino;
 	}
 
-	/* Update the backward pointer. */
-	if (ip->i_prev_unlinked != prev_agino) {
-		trace_xrep_iunlink_relink_prev(ip, prev_agino);
-		ip->i_prev_unlinked = prev_agino;
-	}
+	set_inode_prev_unlinked(ip, prev_agino);
 
 out_rele:
 	/*