[PATCH 2/4] xfs: check AGI unlinked inode buckets

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Look for corruptions in the AGI unlinked bucket chains.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/scrub/agheader.c |   40 ++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_inode.c      |    2 +-
 fs/xfs/xfs_inode.h      |    1 +
 3 files changed, 42 insertions(+), 1 deletion(-)


diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c
index 75de0ba4fcef..fb2f32a2af5d 100644
--- a/fs/xfs/scrub/agheader.c
+++ b/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 (ip->i_prev_unlinked == 0) {
+				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;
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 3788093fc81d..af4ac808a0e0 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2010,7 +2010,7 @@ 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)
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 177b027b8803..be704174fa4f 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -584,6 +584,7 @@ extern struct kmem_cache	*xfs_inode_cache;
 bool xfs_inode_needs_inactive(struct xfs_inode *ip);
 
 int xfs_iunlink(struct xfs_trans *tp, 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);