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radix-tree: introduce radix_tree_load_root() 

All the tree walking functions start with some variant of this code;
centralise it in one place so we're not chasing subtly different bugs
everywhere.

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>
This commit is contained in:
Matthew Wilcox 2016-05-20 17:02:08 -07:00 committed by Linus Torvalds
parent aa54757602
commit 1456a439fc
1 changed files with 23 additions and 0 deletions
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23
lib/radix-tree.c
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@ -405,6 +405,29 @@ static inline unsigned long radix_tree_maxindex(unsigned int height)
return height_to_maxindex[height];
}
static inline unsigned long node_maxindex(struct radix_tree_node *node)
{
return radix_tree_maxindex(node->path & RADIX_TREE_HEIGHT_MASK);
}
static unsigned radix_tree_load_root(struct radix_tree_root *root,
struct radix_tree_node **nodep, unsigned long *maxindex)
{
struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
*nodep = node;
if (likely(radix_tree_is_indirect_ptr(node))) {
node = indirect_to_ptr(node);
*maxindex = node_maxindex(node);
return (node->path & RADIX_TREE_HEIGHT_MASK) *
RADIX_TREE_MAP_SHIFT;
}
*maxindex = 0;
return 0;
}
/*
* Extend a radix tree so it can store key @index.
*/