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radix-tree: fix replacement for multiorder entries

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When replacing an entry with NULL, we need to delete any sibling
entries.  Also account deleting exceptional entries properly.  Also fix
a bug with radix_tree_iter_replace() where we would fail to remove
entirely freed nodes.  Also fix accounting bug when switching between
normal and exceptional entries with replace_slot.  Also add testcases
for all these bugs.

Link: http://lkml.kernel.org/r/1480369871-5271-61-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
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 2016-12-14 15:09:07 -08:00 • committed by Linus Torvalds
parent 2791653a68
commit a90eb3a2a4
2 changed files with 119 additions and 28 deletions
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60
lib/radix-tree.c
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@ -977,6 +977,24 @@ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
}
EXPORT_SYMBOL(radix_tree_lookup);
static inline int slot_count(struct radix_tree_node *node,
void **slot)
{
int n = 1;
#ifdef CONFIG_RADIX_TREE_MULTIORDER
void *ptr = node_to_entry(slot);
unsigned offset = get_slot_offset(node, slot);
int i;
for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
if (node->slots[offset + i] != ptr)
break;
n++;
}
#endif
return n;
}
static void replace_slot(struct radix_tree_root *root,
struct radix_tree_node *node,
void **slot, void *item,
@ -995,12 +1013,35 @@ static void replace_slot(struct radix_tree_root *root,
if (node) {
node->count += count;
node->exceptional += exceptional;
if (exceptional) {
exceptional *= slot_count(node, slot);
node->exceptional += exceptional;
}
}
rcu_assign_pointer(*slot, item);
}
static inline void delete_sibling_entries(struct radix_tree_node *node,
void **slot)
{
#ifdef CONFIG_RADIX_TREE_MULTIORDER
bool exceptional = radix_tree_exceptional_entry(*slot);
void *ptr = node_to_entry(slot);
unsigned offset = get_slot_offset(node, slot);
int i;
for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
if (node->slots[offset + i] != ptr)
break;
node->slots[offset + i] = NULL;
node->count--;
if (exceptional)
node->exceptional--;
}
#endif
}
/**
* __radix_tree_replace - replace item in a slot
* @root: radix tree root
@ -1018,6 +1059,8 @@ void __radix_tree_replace(struct radix_tree_root *root,
void **slot, void *item,
radix_tree_update_node_t update_node, void *private)
{
if (!item)
delete_sibling_entries(node, slot);
/*
* This function supports replacing exceptional entries and
* deleting entries, but that needs accounting against the
@ -1794,20 +1837,6 @@ void __radix_tree_delete_node(struct radix_tree_root *root,
delete_node(root, node, NULL, NULL);
}
static inline void delete_sibling_entries(struct radix_tree_node *node,
void *ptr, unsigned offset)
{
#ifdef CONFIG_RADIX_TREE_MULTIORDER
int i;
for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) {
if (node->slots[offset + i] != ptr)
break;
node->slots[offset + i] = NULL;
node->count--;
}
#endif
}
/**
* radix_tree_delete_item - delete an item from a radix tree
* @root: radix tree root
@ -1847,7 +1876,6 @@ void *radix_tree_delete_item(struct radix_tree_root *root,
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
node_tag_clear(root, node, tag, offset);
delete_sibling_entries(node, node_to_entry(slot), offset);
__radix_tree_replace(root, node, slot, NULL, NULL, NULL);
return entry;