From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
In xrep_findroot_block, if we find a candidate root block with sibling
pointers or sibling blocks on the same tree level, we should not return
that block as a tree root because root blocks cannot have siblings.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/scrub/repair.c | 61 +++++++++++++++++++++++++++++++++++++++----------
1 file changed, 48 insertions(+), 13 deletions(-)
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 9f08dd9bf1d5..63786341ac2a 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -692,12 +692,13 @@ xrep_findroot_block(
struct xrep_find_ag_btree *fab,
uint64_t owner,
xfs_agblock_t agbno,
- bool *found_it)
+ bool *done_with_block)
{
struct xfs_mount *mp = ri->sc->mp;
struct xfs_buf *bp;
struct xfs_btree_block *btblock;
xfs_daddr_t daddr;
+ int block_level;
int error;
daddr = XFS_AGB_TO_DADDR(mp, ri->sc->sa.agno, agbno);
@@ -735,18 +736,52 @@ xrep_findroot_block(
goto out;
bp->b_ops = fab->buf_ops;
- /* Ignore this block if it's lower in the tree than we've seen. */
- if (fab->root != NULLAGBLOCK &&
- xfs_btree_get_level(btblock) < fab->height)
- goto out;
-
/* Make sure we pass the verifiers. */
bp->b_ops->verify_read(bp);
if (bp->b_error)
goto out;
- fab->root = agbno;
- fab->height = xfs_btree_get_level(btblock) + 1;
- *found_it = true;
+
+ /*
+ * This block passes the magic/uuid and verifier tests for this btree
+ * type. We don't need the caller to try the other tree types.
+ */
+ *done_with_block = true;
+
+ /*
+ * Compare this btree block's level to the height of the current
+ * candidate root block.
+ *
+ * If the level matches the root we found previously, throw away both
+ * blocks because there can't be two candidate roots.
+ *
+ * If level is lower in the tree than the root we found previously,
+ * ignore this block.
+ */
+ block_level = xfs_btree_get_level(btblock);
+ if (block_level + 1 == fab->height) {
+ fab->root = NULLAGBLOCK;
+ goto out;
+ } else if (block_level < fab->height) {
+ goto out;
+ }
+
+ /*
+ * This is the highest block in the tree that we've found so far.
+ * Update the btree height to reflect what we've learned from this
+ * block.
+ */
+ fab->height = block_level + 1;
+
+ /*
+ * If this block doesn't have sibling pointers, then it's the new root
+ * block candidate. Otherwise, the root will be found farther up the
+ * tree.
+ */
+ if (btblock->bb_u.s.bb_leftsib == cpu_to_be32(NULLAGBLOCK) &&
+ btblock->bb_u.s.bb_rightsib == cpu_to_be32(NULLAGBLOCK))
+ fab->root = agbno;
+ else
+ fab->root = NULLAGBLOCK;
trace_xrep_findroot_block(mp, ri->sc->sa.agno, agbno,
be32_to_cpu(btblock->bb_magic), fab->height - 1);
@@ -768,7 +803,7 @@ xrep_findroot_rmap(
struct xrep_findroot *ri = priv;
struct xrep_find_ag_btree *fab;
xfs_agblock_t b;
- bool found_it;
+ bool done;
int error = 0;
/* Ignore anything that isn't AG metadata. */
@@ -777,16 +812,16 @@ xrep_findroot_rmap(
/* Otherwise scan each block + btree type. */
for (b = 0; b < rec->rm_blockcount; b++) {
- found_it = false;
+ done = false;
for (fab = ri->btree_info; fab->buf_ops; fab++) {
if (rec->rm_owner != fab->rmap_owner)
continue;
error = xrep_findroot_block(ri, fab,
rec->rm_owner, rec->rm_startblock + b,
- &found_it);
+ &done);
if (error)
return error;
- if (found_it)
+ if (done)
break;
}
}
