radix tree: Remove multiorder support

All users have now been converted to the XArray.  Removing the support
reduces code size and ensures new users will use the XArray instead.

Signed-off-by: Matthew Wilcox <willy@infradead.org>

2 files changed, 13 insertions, 206 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index 40bfa6ccd294..a9965f4af4dd 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -405,10 +405,6 @@ config XARRAY_MULTI
           Support entries which occupy multiple consecutive indices in the
           XArray.
 
-config RADIX_TREE_MULTIORDER
-        bool
-        select XARRAY_MULTI
-
 config ASSOCIATIVE_ARRAY
         bool
         help
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index f107dd2698e3..1106bb6aa01e 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -110,11 +110,6 @@ static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
         unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
         void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
 
-        if (xa_is_sibling(entry)) {
-                offset = xa_to_sibling(entry);
-                entry = rcu_dereference_raw(parent->slots[offset]);
-        }
-
         *nodep = (void *)entry;
         return offset;
 }
@@ -229,7 +224,7 @@ radix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag,
 
 static unsigned int iter_offset(const struct radix_tree_iter *iter)
 {
-        return (iter->index >> iter_shift(iter)) & RADIX_TREE_MAP_MASK;
+        return iter->index & RADIX_TREE_MAP_MASK;
 }
 
 /*
@@ -506,16 +501,13 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root)
 
                 /*
                  * The candidate node has more than one child, or its child
-                 * is not at the leftmost slot, or the child is a multiorder
-                 * entry, we cannot shrink.
+                 * is not at the leftmost slot, we cannot shrink.
                  */
                 if (node->count != 1)
                         break;
                 child = rcu_dereference_raw(node->slots[0]);
                 if (!child)
                         break;
-                if (!radix_tree_is_internal_node(child) && node->shift)
-                        break;
 
                 /*
                  * For an IDR, we must not shrink entry 0 into the root in
@@ -613,7 +605,6 @@ static bool delete_node(struct radix_tree_root *root,
  *      __radix_tree_create     -       create a slot in a radix tree
  *      @root:          radix tree root
  *      @index:         index key
- *      @order:         index occupies 2^order aligned slots
  *      @nodep:         returns node
  *      @slotp:         returns slot
  *
@@ -627,21 +618,19 @@ static bool delete_node(struct radix_tree_root *root,
  *      Returns -ENOMEM, or 0 for success.
  */
 static int __radix_tree_create(struct radix_tree_root *root,
-                unsigned long index, unsigned order,
-                struct radix_tree_node **nodep, void __rcu ***slotp)
+                unsigned long index, struct radix_tree_node **nodep,
+                void __rcu ***slotp)
 {
         struct radix_tree_node *node = NULL, *child;
         void __rcu **slot = (void __rcu **)&root->xa_head;
         unsigned long maxindex;
         unsigned int shift, offset = 0;
-        unsigned long max = index | ((1UL << order) - 1);
+        unsigned long max = index;
         gfp_t gfp = root_gfp_mask(root);
 
         shift = radix_tree_load_root(root, &child, &maxindex);
 
         /* Make sure the tree is high enough.  */
-        if (order > 0 && max == ((1UL << order) - 1))
-                max++;
         if (max > maxindex) {
                 int error = radix_tree_extend(root, gfp, max, shift);
                 if (error < 0)
@@ -650,7 +639,7 @@ static int __radix_tree_create(struct radix_tree_root *root,
                 child = rcu_dereference_raw(root->xa_head);
         }
 
-        while (shift > order) {
+        while (shift > 0) {
                 shift -= RADIX_TREE_MAP_SHIFT;
                 if (child == NULL) {
                         /* Have to add a child node.  */
@@ -711,70 +700,8 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
         }
 }
 
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-static inline int insert_entries(struct radix_tree_node *node,
-                void __rcu **slot, void *item, unsigned order, bool replace)
-{
-        void *sibling;
-        unsigned i, n, tag, offset, tags = 0;
-
-        if (node) {
-                if (order > node->shift)
-                        n = 1 << (order - node->shift);
-                else
-                        n = 1;
-                offset = get_slot_offset(node, slot);
-        } else {
-                n = 1;
-                offset = 0;
-        }
-
-        if (n > 1) {
-                offset = offset & ~(n - 1);
-                slot = &node->slots[offset];
-        }
-        sibling = xa_mk_sibling(offset);
-
-        for (i = 0; i < n; i++) {
-                if (slot[i]) {
-                        if (replace) {
-                                node->count--;
-                                for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-                                        if (tag_get(node, tag, offset + i))
-                                                tags |= 1 << tag;
-                        } else
-                                return -EEXIST;
-                }
-        }
-
-        for (i = 0; i < n; i++) {
-                struct radix_tree_node *old = rcu_dereference_raw(slot[i]);
-                if (i) {
-                        rcu_assign_pointer(slot[i], sibling);
-                        for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-                                if (tags & (1 << tag))
-                                        tag_clear(node, tag, offset + i);
-                } else {
-                        rcu_assign_pointer(slot[i], item);
-                        for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-                                if (tags & (1 << tag))
-                                        tag_set(node, tag, offset);
-                }
-                if (xa_is_node(old))
-                        radix_tree_free_nodes(old);
-                if (xa_is_value(old))
-                        node->nr_values--;
-        }
-        if (node) {
-                node->count += n;
-                if (xa_is_value(item))
-                        node->nr_values += n;
-        }
-        return n;
-}
-#else
 static inline int insert_entries(struct radix_tree_node *node,
-                void __rcu **slot, void *item, unsigned order, bool replace)
+                void __rcu **slot, void *item, bool replace)
 {
         if (*slot)
                 return -EEXIST;
@@ -786,19 +713,17 @@ static inline int insert_entries(struct radix_tree_node *node,
         }
         return 1;
 }
-#endif
 
 /**
  *      __radix_tree_insert    -    insert into a radix tree
  *      @root:          radix tree root
  *      @index:         index key
- *      @order:         key covers the 2^order indices around index
  *      @item:          item to insert
  *
  *      Insert an item into the radix tree at position @index.
  */
-int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
-                        unsigned order, void *item)
+int radix_tree_insert(struct radix_tree_root *root, unsigned long index,
+                        void *item)
 {
         struct radix_tree_node *node;
         void __rcu **slot;
@@ -806,11 +731,11 @@ int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
 
         BUG_ON(radix_tree_is_internal_node(item));
 
-        error = __radix_tree_create(root, index, order, &node, &slot);
+        error = __radix_tree_create(root, index, &node, &slot);
         if (error)
                 return error;
 
-        error = insert_entries(node, slot, item, order, false);
+        error = insert_entries(node, slot, item, false);
         if (error < 0)
                 return error;
 
@@ -825,7 +750,7 @@ int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
 
         return 0;
 }
-EXPORT_SYMBOL(__radix_tree_insert);
+EXPORT_SYMBOL(radix_tree_insert);
 
 /**
  *      __radix_tree_lookup     -       lookup an item in a radix tree
@@ -917,32 +842,12 @@ void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
 }
 EXPORT_SYMBOL(radix_tree_lookup);
 
-static inline void replace_sibling_entries(struct radix_tree_node *node,
-                                void __rcu **slot, int count, int values)
-{
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-        unsigned offset = get_slot_offset(node, slot);
-        void *ptr = xa_mk_sibling(offset);
-
-        while (++offset < RADIX_TREE_MAP_SIZE) {
-                if (rcu_dereference_raw(node->slots[offset]) != ptr)
-                        break;
-                if (count < 0) {
-                        node->slots[offset] = NULL;
-                        node->count--;
-                }
-                node->nr_values += values;
-        }
-#endif
-}
-
 static void replace_slot(void __rcu **slot, void *item,
                 struct radix_tree_node *node, int count, int values)
 {
         if (node && (count || values)) {
                 node->count += count;
                 node->nr_values += values;
-                replace_sibling_entries(node, slot, count, values);
         }
 
         rcu_assign_pointer(*slot, item);
@@ -1223,14 +1128,6 @@ int radix_tree_tag_get(const struct radix_tree_root *root,
 }
 EXPORT_SYMBOL(radix_tree_tag_get);
 
-static inline void __set_iter_shift(struct radix_tree_iter *iter,
-                                        unsigned int shift)
-{
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-        iter->shift = shift;
-#endif
-}
-
 /* Construct iter->tags bit-mask from node->tags[tag] array */
 static void set_iter_tags(struct radix_tree_iter *iter,
                                 struct radix_tree_node *node, unsigned offset,
@@ -1257,92 +1154,11 @@ static void set_iter_tags(struct radix_tree_iter *iter,
         }
 }
 
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-static void __rcu **skip_siblings(struct radix_tree_node **nodep,
-                        void __rcu **slot, struct radix_tree_iter *iter)
-{
-        while (iter->index < iter->next_index) {
-                *nodep = rcu_dereference_raw(*slot);
-                if (*nodep && !xa_is_sibling(*nodep))
-                        return slot;
-                slot++;
-                iter->index = __radix_tree_iter_add(iter, 1);
-                iter->tags >>= 1;
-        }
-
-        *nodep = NULL;
-        return NULL;
-}
-
-void __rcu **__radix_tree_next_slot(void __rcu **slot,
-                                struct radix_tree_iter *iter, unsigned flags)
-{
-        unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK;
-        struct radix_tree_node *node;
-
-        slot = skip_siblings(&node, slot, iter);
-
-        while (radix_tree_is_internal_node(node)) {
-                unsigned offset;
-                unsigned long next_index;
-
-                if (node == RADIX_TREE_RETRY)
-                        return slot;
-                node = entry_to_node(node);
-                iter->node = node;
-                iter->shift = node->shift;
-
-                if (flags & RADIX_TREE_ITER_TAGGED) {
-                        offset = radix_tree_find_next_bit(node, tag, 0);
-                        if (offset == RADIX_TREE_MAP_SIZE)
-                                return NULL;
-                        slot = &node->slots[offset];
-                        iter->index = __radix_tree_iter_add(iter, offset);
-                        set_iter_tags(iter, node, offset, tag);
-                        node = rcu_dereference_raw(*slot);
-                } else {
-                        offset = 0;
-                        slot = &node->slots[0];
-                        for (;;) {
-                                node = rcu_dereference_raw(*slot);
-                                if (node)
-                                        break;
-                                slot++;
-                                offset++;
-                                if (offset == RADIX_TREE_MAP_SIZE)
-                                        return NULL;
-                        }
-                        iter->index = __radix_tree_iter_add(iter, offset);
-                }
-                if ((flags & RADIX_TREE_ITER_CONTIG) && (offset > 0))
-                        goto none;
-                next_index = (iter->index | shift_maxindex(iter->shift)) + 1;
-                if (next_index < iter->next_index)
-                        iter->next_index = next_index;
-        }
-
-        return slot;
- none:
-        iter->next_index = 0;
-        return NULL;
-}
-EXPORT_SYMBOL(__radix_tree_next_slot);
-#else
-static void __rcu **skip_siblings(struct radix_tree_node **nodep,
-                        void __rcu **slot, struct radix_tree_iter *iter)
-{
-        return slot;
-}
-#endif
-
 void __rcu **radix_tree_iter_resume(void __rcu **slot,
                                         struct radix_tree_iter *iter)
 {
-        struct radix_tree_node *node;
-
         slot++;
         iter->index = __radix_tree_iter_add(iter, 1);
-        skip_siblings(&node, slot, iter);
         iter->next_index = iter->index;
         iter->tags = 0;
         return NULL;
@@ -1393,7 +1209,6 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
                 iter->next_index = maxindex + 1;
                 iter->tags = 1;
                 iter->node = NULL;
-                __set_iter_shift(iter, 0);
                 return (void __rcu **)&root->xa_head;
         }
 
@@ -1414,8 +1229,6 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
                                 while (++offset < RADIX_TREE_MAP_SIZE) {
                                         void *slot = rcu_dereference_raw(
                                                         node->slots[offset]);
-                                        if (xa_is_sibling(slot))
-                                                continue;
                                         if (slot)
                                                 break;
                                 }
@@ -1436,10 +1249,9 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
         } while (node->shift && radix_tree_is_internal_node(child));
 
         /* Update the iterator state */
-        iter->index = (index &~ node_maxindex(node)) | (offset << node->shift);
+        iter->index = (index &~ node_maxindex(node)) | offset;
         iter->next_index = (index | node_maxindex(node)) + 1;
         iter->node = node;
-        __set_iter_shift(iter, node->shift);
 
         if (flags & RADIX_TREE_ITER_TAGGED)
                 set_iter_tags(iter, node, offset, tag);
@@ -1750,7 +1562,6 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
         else
                 iter->next_index = 1;
         iter->node = node;
-        __set_iter_shift(iter, shift);
         set_iter_tags(iter, node, offset, IDR_FREE);
 
         return slot;