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authorMatthew Wilcox <willy@linux.intel.com>2016-12-14 15:09:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-14 16:04:10 -0800
commite157b555945fb16ddc6cce605a1eb6b4135ea5f1 (patch)
treef0b53b641059c010cfd38a32ae7f4f3b27b04303 /include
parent175542f575723e43f897ddb09d0011c13f7cf0ec (diff)
radix-tree: add radix_tree_split
This new function splits a larger multiorder entry into smaller entries (potentially multi-order entries). These entries are initialised to RADIX_TREE_RETRY to ensure that RCU walkers who see this state aren't confused. The caller should then call radix_tree_for_each_slot() and radix_tree_replace_slot() in order to turn these retry entries into the intended new entries. Tags are replicated from the original multiorder entry into each new entry. Link: http://lkml.kernel.org/r/1480369871-5271-59-git-send-email-mawilcox@linuxonhyperv.com Signed-off-by: Matthew Wilcox <willy@linux.intel.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>
Diffstat (limited to 'include')
-rw-r--r--include/linux/radix-tree.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 935293a24f7d..1f4b56120de8 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -80,6 +80,14 @@ static inline bool radix_tree_is_internal_node(void *ptr)
#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
RADIX_TREE_MAP_SHIFT))
+/*
+ * @count is the count of every non-NULL element in the ->slots array
+ * whether that is an exceptional entry, a retry entry, a user pointer,
+ * a sibling entry or a pointer to the next level of the tree.
+ * @exceptional is the count of every element in ->slots which is
+ * either radix_tree_exceptional_entry() or is a sibling entry for an
+ * exceptional entry.
+ */
struct radix_tree_node {
unsigned char shift; /* Bits remaining in each slot */
unsigned char offset; /* Slot offset in parent */
@@ -293,6 +301,8 @@ void __radix_tree_replace(struct radix_tree_root *root,
struct radix_tree_node *node,
void **slot, void *item,
radix_tree_update_node_t update_node, void *private);
+void radix_tree_iter_replace(struct radix_tree_root *,
+ const struct radix_tree_iter *, void **slot, void *item);
void radix_tree_replace_slot(struct radix_tree_root *root,
void **slot, void *item);
void __radix_tree_delete_node(struct radix_tree_root *root,
@@ -335,6 +345,8 @@ static inline void radix_tree_preload_end(void)
preempt_enable();
}
+int radix_tree_split(struct radix_tree_root *, unsigned long index,
+ unsigned new_order);
int radix_tree_join(struct radix_tree_root *, unsigned long index,
unsigned new_order, void *);