From 08a3a692ef586cc82648b88856a97e0d173319e2 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Wed, 9 May 2018 10:02:00 -0700
Subject: [PATCH] xfs: btree scrub should check minrecs
Strengthen the btree block header checks to detect the number of records
being less than the btree type's minimum record count. Certain blocks
are allowed to violate this constraint -- specifically any btree block
at the top of the tree can have fewer than minrecs records.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
fs/xfs/scrub/btree.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
index ea972dab14852..2d29dceaa00e7 100644
--- a/fs/xfs/scrub/btree.c
+++ b/fs/xfs/scrub/btree.c
@@ -454,6 +454,44 @@ xfs_scrub_btree_check_owner(
return xfs_scrub_btree_check_block_owner(bs, level, XFS_BUF_ADDR(bp));
}
+/*
+ * Check that this btree block has at least minrecs records or is one of the
+ * special blocks that don't require that.
+ */
+STATIC void
+xfs_scrub_btree_check_minrecs(
+ struct xfs_scrub_btree *bs,
+ int level,
+ struct xfs_btree_block *block)
+{
+ unsigned int numrecs;
+ int ok_level;
+
+ numrecs = be16_to_cpu(block->bb_numrecs);
+
+ /* More records than minrecs means the block is ok. */
+ if (numrecs >= bs->cur->bc_ops->get_minrecs(bs->cur, level))
+ return;
+
+ /*
+ * Certain btree blocks /can/ have fewer than minrecs records. Any
+ * level greater than or equal to the level of the highest dedicated
+ * btree block are allowed to violate this constraint.
+ *
+ * For a btree rooted in a block, the btree root can have fewer than
+ * minrecs records. If the btree is rooted in an inode and does not
+ * store records in the root, the direct children of the root and the
+ * root itself can have fewer than minrecs records.
+ */
+ ok_level = bs->cur->bc_nlevels - 1;
+ if (bs->cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
+ ok_level--;
+ if (level >= ok_level)
+ return;
+
+ xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, level);
+}
+
/*
* Grab and scrub a btree block given a btree pointer. Returns block
* and buffer pointers (if applicable) if they're ok to use.
@@ -491,6 +529,8 @@ xfs_scrub_btree_get_block(
if (*pbp)
xfs_scrub_buffer_recheck(bs->sc, *pbp);
+ xfs_scrub_btree_check_minrecs(bs, level, *pblock);
+
/*
* Check the block's owner; this function absorbs error codes
* for us.
--
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