radix-tree: fix multiorder BUG_ON in radix_tree_insert
These BUG_ON tests are to ensure that all the tags are clear when
inserting a new entry. If we insert a multiorder entry, we'll end up
looking at the tags for a different node, and so the BUG_ON can end up
triggering spuriously.
Also, we now have three tags, not two, so check all three are clear, and
check all the root tags with a single call to BUG_ON since the bits are
stored contiguously.
Include a test-case to ensure this problem does not reoccur.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index f14ada9..ff46042 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -165,6 +165,11 @@
return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
}
+static inline unsigned root_tags_get(struct radix_tree_root *root)
+{
+ return (__force unsigned)root->gfp_mask >> __GFP_BITS_SHIFT;
+}
+
/*
* Returns 1 if any slot in the node has this tag set.
* Otherwise returns 0.
@@ -604,12 +609,13 @@
rcu_assign_pointer(*slot, item);
if (node) {
+ unsigned offset = get_slot_offset(node, slot);
node->count++;
- BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK));
- BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK));
+ BUG_ON(tag_get(node, 0, offset));
+ BUG_ON(tag_get(node, 1, offset));
+ BUG_ON(tag_get(node, 2, offset));
} else {
- BUG_ON(root_tag_get(root, 0));
- BUG_ON(root_tag_get(root, 1));
+ BUG_ON(root_tags_get(root));
}
return 0;