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radix-tree: tidy up next_chunk

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Convert radix_tree_next_chunk to use 'child' instead of 'slot' as the
name of the child node.  Also use node_maxindex() where it makes sense.

The 'rnode' variable was unnecessary; it doesn't overlap in usage with
'node', so we can just use 'node' the whole way through the function.

Improve the testcase to start the walk from every index in the carefully
constructed tree, and to accept any index within the range covered by
the entry.

Signed-off-by: Matthew Wilcox <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Kirill Shutemov <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Ross Zwisler <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Matthew Wilcox 2016-05-20 17:03:36 -07:00 • committed by Linus Torvalds
commit 8c1244de00
2 changed files with 74 additions and 78 deletions
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53
lib/radix-tree.c
View file

@ -876,7 +876,7 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
struct radix_tree_iter *iter, unsigned flags)
{
unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK;
struct radix_tree_node *rnode, *node;
struct radix_tree_node *node, *child;
unsigned long index, offset, maxindex;
if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag))
@ -896,38 +896,29 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
return NULL;
restart:
shift = radix_tree_load_root(root, &rnode, &maxindex);
shift = radix_tree_load_root(root, &child, &maxindex);
if (index > maxindex)
return NULL;
if (!child)
return NULL;
if (radix_tree_is_internal_node(rnode)) {
rnode = entry_to_node(rnode);
} else if (rnode) {
if (!radix_tree_is_internal_node(child)) {
/* Single-slot tree */
iter->index = index;
iter->next_index = maxindex + 1;
iter->tags = 1;
__set_iter_shift(iter, shift);
__set_iter_shift(iter, 0);
return (void **)&root->rnode;
} else
return NULL;
}
shift -= RADIX_TREE_MAP_SHIFT;
offset = index >> shift;
node = rnode;
while (1) {
struct radix_tree_node *slot;
unsigned new_off = radix_tree_descend(node, &slot, offset);
if (new_off < offset) {
offset = new_off;
index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1);
index |= offset << shift;
}
do {
node = entry_to_node(child);
shift -= RADIX_TREE_MAP_SHIFT;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
offset = radix_tree_descend(node, &child, offset);
if ((flags & RADIX_TREE_ITER_TAGGED) ?
!tag_get(node, tag, offset) : !slot) {
!tag_get(node, tag, offset) : !child) {
/* Hole detected */
if (flags & RADIX_TREE_ITER_CONTIG)
return NULL;
@ -945,29 +936,23 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
if (slot)
break;
}
index &= ~((RADIX_TREE_MAP_SIZE << shift) - 1);
index &= ~node_maxindex(node);
index += offset << shift;
/* Overflow after ~0UL */
if (!index)
return NULL;
if (offset == RADIX_TREE_MAP_SIZE)
goto restart;
slot = rcu_dereference_raw(node->slots[offset]);
child = rcu_dereference_raw(node->slots[offset]);
}
if ((slot == NULL) || (slot == RADIX_TREE_RETRY))
if ((child == NULL) || (child == RADIX_TREE_RETRY))
goto restart;
if (!radix_tree_is_internal_node(slot))
break;
node = entry_to_node(slot);
shift -= RADIX_TREE_MAP_SHIFT;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
}
} while (radix_tree_is_internal_node(child));
/* Update the iterator state */
iter->index = index & ~((1 << shift) - 1);
iter->next_index = (index | ((RADIX_TREE_MAP_SIZE << shift) - 1)) + 1;
iter->index = (index &~ node_maxindex(node)) | (offset << node->shift);
iter->next_index = (index | node_maxindex(node)) + 1;
__set_iter_shift(iter, shift);
/* Construct iter->tags bit-mask from node->tags[tag] array */