xfs: check AGI unlinked inode buckets

Look for corruptions in the AGI unlinked bucket chains.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/scrub/agheader.c

@@ -15,6 +15,7 @@
 #include "xfs_ialloc.h"
 #include "xfs_rmap.h"
 #include "xfs_ag.h"
+#include "xfs_inode.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 
@@ -865,6 +866,43 @@ xchk_agi_xref(
 	/* scrub teardown will take care of sc->sa for us */
 }
 
+/*
+ * Check the unlinked buckets for links to bad inodes.  We hold the AGI, so
+ * there cannot be any threads updating unlinked list pointers in this AG.
+ */
+STATIC void
+xchk_iunlink(
+	struct xfs_scrub	*sc,
+	struct xfs_agi		*agi)
+{
+	unsigned int		i;
+	struct xfs_inode	*ip;
+
+	for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++) {
+		xfs_agino_t	agino = be32_to_cpu(agi->agi_unlinked[i]);
+
+		while (agino != NULLAGINO) {
+			if (agino % XFS_AGI_UNLINKED_BUCKETS != i) {
+				xchk_block_set_corrupt(sc, sc->sa.agi_bp);
+				return;
+			}
+
+			ip = xfs_iunlink_lookup(sc->sa.pag, agino);
+			if (!ip) {
+				xchk_block_set_corrupt(sc, sc->sa.agi_bp);
+				return;
+			}
+
+			if (!xfs_inode_on_unlinked_list(ip)) {
+				xchk_block_set_corrupt(sc, sc->sa.agi_bp);
+				return;
+			}
+
+			agino = ip->i_next_unlinked;
+		}
+	}
+}
+
 /* Scrub the AGI. */
 int
 xchk_agi(
@@ -949,6 +987,8 @@ xchk_agi(
 	if (pag->pagi_freecount != be32_to_cpu(agi->agi_freecount))
 		xchk_block_set_corrupt(sc, sc->sa.agi_bp);
 
+	xchk_iunlink(sc, agi);
+
 	xchk_agi_xref(sc);
 out:
 	return error;

fs/xfs/xfs_inode.c

@@ -1985,7 +1985,7 @@ xfs_inactive(
  * only unlinked, referenced inodes can be on the unlinked inode list.  If we
  * don't find the inode in cache, then let the caller handle the situation.
  */
-static struct xfs_inode *
+struct xfs_inode *
 xfs_iunlink_lookup(
 	struct xfs_perag	*pag,
 	xfs_agino_t		agino)

fs/xfs/xfs_inode.h

@@ -619,6 +619,7 @@ bool xfs_inode_needs_inactive(struct xfs_inode *ip);
 int xfs_iunlink(struct xfs_trans *tp, struct xfs_inode *ip);
 int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
 		struct xfs_inode *ip);
+struct xfs_inode *xfs_iunlink_lookup(struct xfs_perag *pag, xfs_agino_t agino);
 
 void xfs_end_io(struct work_struct *work);