From: Matthew Wilcox <mawil...@microsoft.com>

Use the xarray infrstructure like we used the radix tree infrastructure.
This lets us get rid of idr_get_free() from the radix tree code.

Signed-off-by: Matthew Wilcox <mawil...@microsoft.com>
---
 include/linux/idr.h        |   8 +-
 include/linux/radix-tree.h |   4 -
 lib/idr.c                  | 320 ++++++++++++++++++++++++++-------------------
 lib/radix-tree.c           | 126 ------------------
 4 files changed, 187 insertions(+), 271 deletions(-)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index 06412fbaa65f..d6b3dbe483b8 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -245,11 +245,11 @@ struct ida_bitmap {
 DECLARE_PER_CPU(struct ida_bitmap *, ida_bitmap);
 
 struct ida {
-       struct radix_tree_root  ida_rt;
+       struct xarray   ida_xa;
 };
 
 #define IDA_INIT(name) {                                               \
-       .ida_rt = RADIX_TREE_INIT(name, IDR_INIT_FLAGS | GFP_NOWAIT),   \
+       .ida_xa = __XARRAY_INIT(name.ida_xa, IDR_INIT_FLAGS)            \
 }
 #define DEFINE_IDA(name)       struct ida name = IDA_INIT(name)
 
@@ -264,7 +264,7 @@ void ida_simple_remove(struct ida *ida, unsigned int id);
 
 static inline void ida_init(struct ida *ida)
 {
-       INIT_RADIX_TREE(&ida->ida_rt, IDR_INIT_FLAGS | GFP_NOWAIT);
+       __xa_init(&ida->ida_xa, IDR_INIT_FLAGS);
 }
 
 /**
@@ -281,6 +281,6 @@ static inline int ida_get_new(struct ida *ida, int *p_id)
 
 static inline bool ida_is_empty(const struct ida *ida)
 {
-       return radix_tree_empty(&ida->ida_rt);
+       return xa_empty(&ida->ida_xa);
 }
 #endif /* _LINUX_IDR_H */
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index f46e3de57115..5d67939b8cd0 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -301,10 +301,6 @@ int radix_tree_split(struct radix_tree_root *, unsigned 
long index,
 int radix_tree_join(struct radix_tree_root *, unsigned long index,
                        unsigned new_order, void *);
 
-void __rcu **idr_get_free(struct radix_tree_root *root,
-                             struct radix_tree_iter *iter, gfp_t gfp,
-                             unsigned long max);
-
 enum {
        RADIX_TREE_ITER_TAG_MASK = 0x0f,        /* tag index in lower nybble */
        RADIX_TREE_ITER_TAGGED   = 0x10,        /* lookup tagged slots */
diff --git a/lib/idr.c b/lib/idr.c
index e677d1869ead..eb145da485f2 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -6,7 +6,6 @@
 #include <linux/xarray.h>
 
 DEFINE_PER_CPU(struct ida_bitmap *, ida_bitmap);
-static DEFINE_SPINLOCK(simple_ida_lock);
 
 /* In radix-tree.c temporarily */
 extern bool idr_nomem(struct xa_state *, gfp_t);
@@ -307,26 +306,23 @@ EXPORT_SYMBOL_GPL(idr_replace);
 /*
  * Developer's notes:
  *
- * The IDA uses the functionality provided by the IDR & radix tree to store
- * bitmaps in each entry.  The XA_FREE_TAG tag means there is at least one bit
- * free, unlike the IDR where it means at least one entry is free.
- *
- * I considered telling the radix tree that each slot is an order-10 node
- * and storing the bit numbers in the radix tree, but the radix tree can't
- * allow a single multiorder entry at index 0, which would significantly
- * increase memory consumption for the IDA.  So instead we divide the index
- * by the number of bits in the leaf bitmap before doing a radix tree lookup.
- *
- * As an optimisation, if there are only a few low bits set in any given
- * leaf, instead of allocating a 128-byte bitmap, we store the bits
+ * The IDA uses the functionality provided by the IDR & XArray to store
+ * bitmaps in each entry.  The XA_FREE_TAG tag is used to mean that there
+ * is at least one bit free, unlike the IDR where it means at least one
+ * array entry is free.
+ *
+ * The XArray supports multi-index entries, so I considered teaching the
+ * XArray that each slot is an order-10 node and indexing the XArray by the
+ * ID.  The XArray has the significant optimisation of storing the first
+ * entry in the struct xarray and avoiding allocating an xa_node.
+ * Unfortunately, it can't do that for multi-order entries.
+ * So instead the XArray index is the ID divided by the number of bits in
+ * the bitmap
+ *
+ * As a further optimisation, if there are only a few low bits set in any
+ * given leaf, instead of allocating a 128-byte bitmap, we store the bits
  * directly in the entry.
  *
- * We allow the radix tree 'exceptional' count to get out of date.  Nothing
- * in the IDA nor the radix tree code checks it.  If it becomes important
- * to maintain an accurate exceptional count, switch the rcu_assign_pointer()
- * calls to radix_tree_iter_replace() which will correct the exceptional
- * count.
- *
  * The IDA always requires a lock to alloc/free.  If we add a 'test_bit'
  * equivalent, it will still need locking.  Going to RCU lookup would require
  * using RCU to free bitmaps, and that's not trivial without embedding an
@@ -336,104 +332,114 @@ EXPORT_SYMBOL_GPL(idr_replace);
 
 #define IDA_MAX (0x80000000U / IDA_BITMAP_BITS - 1)
 
+static struct ida_bitmap *alloc_ida_bitmap(void)
+{
+       struct ida_bitmap *bitmap = this_cpu_xchg(ida_bitmap, NULL);
+       if (bitmap)
+               memset(bitmap, 0, sizeof(*bitmap));
+       return bitmap;
+}
+
+static void free_ida_bitmap(struct ida_bitmap *bitmap)
+{
+       if (this_cpu_cmpxchg(ida_bitmap, NULL, bitmap))
+               kfree(bitmap);
+}
+
 /**
  * ida_get_new_above - allocate new ID above or equal to a start id
  * @ida: ida handle
  * @start: id to start search at
  * @id: pointer to the allocated handle
  *
- * Allocate new ID above or equal to @start.  It should be called
- * with any required locks to ensure that concurrent calls to
- * ida_get_new_above() / ida_get_new() / ida_remove() are not allowed.
- * Consider using ida_simple_get() if you do not have complex locking
- * requirements.
+ * Allocate new ID above or equal to @start.  The ida has its own lock,
+ * although you may wish to provide your own locking around it.
  *
  * If memory is required, it will return %-EAGAIN, you should unlock
  * and go back to the ida_pre_get() call.  If the ida is full, it will
  * return %-ENOSPC.  On success, it will return 0.
  *
- * @id returns a value in the range @start ... %0x7fffffff.
+ * @id returns a value in the range @start ... %INT_MAX.
  */
 int ida_get_new_above(struct ida *ida, int start, int *id)
 {
-       struct radix_tree_root *root = &ida->ida_rt;
-       void __rcu **slot;
-       struct radix_tree_iter iter;
+       unsigned long flags;
+       unsigned long index = start / IDA_BITMAP_BITS;
+       unsigned int bit = start % IDA_BITMAP_BITS;
+       XA_STATE(xas, &ida->ida_xa, index);
        struct ida_bitmap *bitmap;
-       unsigned long index;
-       unsigned bit;
-       int new;
-
-       index = start / IDA_BITMAP_BITS;
-       bit = start % IDA_BITMAP_BITS;
-
-       slot = radix_tree_iter_init(&iter, index);
-       for (;;) {
-               if (slot)
-                       slot = radix_tree_next_slot(slot, &iter,
-                                               RADIX_TREE_ITER_TAGGED);
-               if (!slot) {
-                       slot = idr_get_free(root, &iter, GFP_NOWAIT, IDA_MAX);
-                       if (IS_ERR(slot)) {
-                               if (slot == ERR_PTR(-ENOMEM))
-                                       return -EAGAIN;
-                               return PTR_ERR(slot);
-                       }
-               }
-               if (iter.index > index)
-                       bit = 0;
-               new = iter.index * IDA_BITMAP_BITS;
-               bitmap = rcu_dereference_raw(*slot);
-               if (xa_is_value(bitmap)) {
-                       unsigned long tmp = xa_to_value(bitmap);
-                       int vbit = find_next_zero_bit(&tmp, BITS_PER_XA_VALUE,
-                                                       bit);
-                       if (vbit < BITS_PER_XA_VALUE) {
-                               tmp |= 1UL << vbit;
-                               rcu_assign_pointer(*slot, xa_mk_value(tmp));
-                               *id = new + vbit;
-                               return 0;
-                       }
-                       bitmap = this_cpu_xchg(ida_bitmap, NULL);
-                       if (!bitmap)
-                               return -EAGAIN;
-                       memset(bitmap, 0, sizeof(*bitmap));
-                       bitmap->bitmap[0] = tmp;
-                       rcu_assign_pointer(*slot, bitmap);
-               }
+       unsigned int new;
+
+       xas_lock_irqsave(&xas, flags);
+retry:
+       bitmap = xas_find_tag(&xas, IDA_MAX, XA_FREE_TAG);
+       if (xas.xa_index > IDA_MAX)
+               goto nospc;
+       if (xas.xa_index > index)
+               bit = 0;
+       new = xas.xa_index * IDA_BITMAP_BITS;
+       if (xa_is_value(bitmap)) {
+               unsigned long value = xa_to_value(bitmap);
+               if (bit < BITS_PER_XA_VALUE) {
+                       unsigned long tmp = value | ((1UL << bit) - 1);
+                       bit = ffz(tmp);
 
-               if (bitmap) {
-                       bit = find_next_zero_bit(bitmap->bitmap,
-                                                       IDA_BITMAP_BITS, bit);
-                       new += bit;
-                       if (new < 0)
-                               return -ENOSPC;
-                       if (bit == IDA_BITMAP_BITS)
-                               continue;
-
-                       __set_bit(bit, bitmap->bitmap);
-                       if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS))
-                               radix_tree_iter_tag_clear(root, &iter,
-                                                               XA_FREE_TAG);
-               } else {
-                       new += bit;
-                       if (new < 0)
-                               return -ENOSPC;
                        if (bit < BITS_PER_XA_VALUE) {
-                               bitmap = xa_mk_value(1UL << bit);
-                       } else {
-                               bitmap = this_cpu_xchg(ida_bitmap, NULL);
-                               if (!bitmap)
-                                       return -EAGAIN;
-                               memset(bitmap, 0, sizeof(*bitmap));
-                               __set_bit(bit, bitmap->bitmap);
+                               value |= (1UL << bit);
+                               xas_store(&xas, xa_mk_value(value));
+                               new += bit;
+                               goto unlock;
                        }
-                       radix_tree_iter_replace(root, &iter, slot, bitmap);
                }
 
-               *id = new;
-               return 0;
+               bitmap = alloc_ida_bitmap();
+               if (!bitmap)
+                       goto nomem;
+               bitmap->bitmap[0] = value;
+               new += bit;
+               __set_bit(bit, bitmap->bitmap);
+               xas_store(&xas, bitmap);
+               if (xas_error(&xas))
+                       free_ida_bitmap(bitmap);
+       } else if (bitmap) {
+               bit = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, bit);
+               if (bit == IDA_BITMAP_BITS)
+                       goto retry;
+               new += bit;
+               if (new > INT_MAX)
+                       goto nospc;
+               __set_bit(bit, bitmap->bitmap);
+               if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS))
+                       xas_clear_tag(&xas, XA_FREE_TAG);
+       } else if (bit < BITS_PER_XA_VALUE) {
+               new += bit;
+               bitmap = xa_mk_value(1UL << bit);
+               xas_store(&xas, bitmap);
+       } else {
+               bitmap = alloc_ida_bitmap();
+               if (!bitmap)
+                       goto nomem;
+               new += bit;
+               __set_bit(bit, bitmap->bitmap);
+               xas_store(&xas, bitmap);
+               if (xas_error(&xas))
+                       free_ida_bitmap(bitmap);
        }
+
+       if (idr_nomem(&xas, GFP_NOWAIT))
+               goto retry;
+unlock:
+       xas_unlock_irqrestore(&xas, flags);
+       if (xas_error(&xas) == -ENOMEM)
+               return -EAGAIN;
+       *id = new;
+       return 0;
+nospc:
+       xas_unlock_irqrestore(&xas, flags);
+       return -ENOSPC;
+nomem:
+       xas_unlock_irqrestore(&xas, flags);
+       return -EAGAIN;
 }
 EXPORT_SYMBOL(ida_get_new_above);
 
@@ -441,45 +447,44 @@ EXPORT_SYMBOL(ida_get_new_above);
  * ida_remove - Free the given ID
  * @ida: ida handle
  * @id: ID to free
- *
- * This function should not be called at the same time as ida_get_new_above().
  */
 void ida_remove(struct ida *ida, int id)
 {
+       unsigned long flags;
        unsigned long index = id / IDA_BITMAP_BITS;
-       unsigned offset = id % IDA_BITMAP_BITS;
+       unsigned bit = id % IDA_BITMAP_BITS;
+       XA_STATE(xas, &ida->ida_xa, index);
        struct ida_bitmap *bitmap;
-       unsigned long *btmp;
-       struct radix_tree_iter iter;
-       void __rcu **slot;
 
-       slot = radix_tree_iter_lookup(&ida->ida_rt, &iter, index);
-       if (!slot)
+       xas_lock_irqsave(&xas, flags);
+       bitmap = xas_load(&xas);
+       if (!bitmap)
                goto err;
-
-       bitmap = rcu_dereference_raw(*slot);
        if (xa_is_value(bitmap)) {
-               btmp = (unsigned long *)slot;
-               offset += 1; /* Intimate knowledge of the xa_data encoding */
-               if (offset >= BITS_PER_LONG)
+               unsigned long v = xa_to_value(bitmap);
+               if (bit >= BITS_PER_XA_VALUE)
                        goto err;
+               if (!(v & (1UL << bit)))
+                       goto err;
+               v &= ~(1UL << bit);
+               if (v)
+                       bitmap = xa_mk_value(v);
+               else
+                       bitmap = NULL;
+               xas_store(&xas, bitmap);
        } else {
-               btmp = bitmap->bitmap;
-       }
-       if (!test_bit(offset, btmp))
-               goto err;
-
-       __clear_bit(offset, btmp);
-       radix_tree_iter_tag_set(&ida->ida_rt, &iter, XA_FREE_TAG);
-       if (xa_is_value(bitmap)) {
-               if (xa_to_value(rcu_dereference_raw(*slot)) == 0)
-                       radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
-       } else if (bitmap_empty(btmp, IDA_BITMAP_BITS)) {
-               kfree(bitmap);
-               radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
+               if (!__test_and_clear_bit(bit, bitmap->bitmap))
+                       goto err;
+               if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
+                       kfree(bitmap);
+                       xas_store(&xas, NULL);
+               }
        }
+       xas_set_tag(&xas, XA_FREE_TAG);
+       xas_unlock_irqrestore(&xas, flags);
        return;
  err:
+       xas_unlock_irqrestore(&xas, flags);
        WARN(1, "ida_remove called for id=%d which is not allocated.\n", id);
 }
 EXPORT_SYMBOL(ida_remove);
@@ -489,21 +494,21 @@ EXPORT_SYMBOL(ida_remove);
  * @ida: ida handle
  *
  * Calling this function releases all resources associated with an IDA.  When
- * this call returns, the IDA is empty and can be reused or freed.  The caller
- * should not allow ida_remove() or ida_get_new_above() to be called at the
- * same time.
+ * this call returns, the IDA is empty and can be reused or freed.
  */
 void ida_destroy(struct ida *ida)
 {
-       struct radix_tree_iter iter;
-       void __rcu **slot;
+       XA_STATE(xas, &ida->ida_xa, 0);
+       unsigned long flags;
+       struct ida_bitmap *bitmap;
 
-       radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) {
-               struct ida_bitmap *bitmap = rcu_dereference_raw(*slot);
+       xas_lock_irqsave(&xas, flags);
+       xas_for_each(&xas, bitmap, ULONG_MAX) {
                if (!xa_is_value(bitmap))
                        kfree(bitmap);
-               radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
+               xas_store(&xas, NULL);
        }
+       xas_unlock_irqrestore(&xas, flags);
 }
 EXPORT_SYMBOL(ida_destroy);
 
@@ -527,7 +532,6 @@ int ida_simple_get(struct ida *ida, unsigned int start, 
unsigned int end,
 {
        int ret, id;
        unsigned int max;
-       unsigned long flags;
 
        BUG_ON((int)start < 0);
        BUG_ON((int)end < 0);
@@ -543,7 +547,6 @@ int ida_simple_get(struct ida *ida, unsigned int start, 
unsigned int end,
        if (!ida_pre_get(ida, gfp_mask))
                return -ENOMEM;
 
-       spin_lock_irqsave(&simple_ida_lock, flags);
        ret = ida_get_new_above(ida, start, &id);
        if (!ret) {
                if (id > max) {
@@ -553,7 +556,6 @@ int ida_simple_get(struct ida *ida, unsigned int start, 
unsigned int end,
                        ret = id;
                }
        }
-       spin_unlock_irqrestore(&simple_ida_lock, flags);
 
        if (unlikely(ret == -EAGAIN))
                goto again;
@@ -574,11 +576,55 @@ EXPORT_SYMBOL(ida_simple_get);
  */
 void ida_simple_remove(struct ida *ida, unsigned int id)
 {
-       unsigned long flags;
-
        BUG_ON((int)id < 0);
-       spin_lock_irqsave(&simple_ida_lock, flags);
        ida_remove(ida, id);
-       spin_unlock_irqrestore(&simple_ida_lock, flags);
 }
 EXPORT_SYMBOL(ida_simple_remove);
+
+#ifdef XA_DEBUG
+static void dump_ida_node(void *entry, unsigned long index)
+{
+       unsigned long i;
+
+       if (!entry)
+               return;
+
+       if (xa_is_node(entry)) {
+               struct xa_node *node = xa_to_node(entry);
+               unsigned long first = index * IDA_BITMAP_BITS;
+               unsigned long last = first | ((((unsigned long)XA_CHUNK_SIZE *
+                                       IDA_BITMAP_BITS) << node->shift) - 1);
+
+               pr_debug("ida node: %p offset %d indices %lu-%lu parent %p free 
%lx shift %d count %d\n",
+                       node, node->offset, first, last, node->parent,
+                       node->tags[0][0], node->shift, node->count);
+               for (i = 0; i < XA_CHUNK_SIZE; i++)
+                       dump_ida_node(node->slots[i],
+                                       index | (i << node->shift));
+       } else if (xa_is_value(entry)) {
+               pr_debug("ida excp: %p offset %d indices %lu-%lu data %lx\n",
+                               entry, (int)(index & XA_CHUNK_MASK),
+                               index * IDA_BITMAP_BITS,
+                               index * IDA_BITMAP_BITS + BITS_PER_XA_VALUE,
+                               xa_to_value(entry));
+       } else {
+               struct ida_bitmap *bitmap = entry;
+
+               pr_debug("ida btmp: %p offset %d indices %lu-%lu data", bitmap,
+                               (int)(index & XA_CHUNK_MASK),
+                               index * IDA_BITMAP_BITS,
+                               (index + 1) * IDA_BITMAP_BITS - 1);
+               for (i = 0; i < IDA_BITMAP_LONGS; i++)
+                       pr_cont(" %lx", bitmap->bitmap[i]);
+               pr_cont("\n");
+       }
+}
+
+void ida_dump(struct ida *ida)
+{
+       struct xarray *xa = &ida->ida_xa;
+       pr_debug("ida: %p node %p free %d\n", ida, xa->xa_head,
+                               xa->xa_flags >> ROOT_TAG_SHIFT);
+       dump_ida_node(xa->xa_head, 0);
+}
+#endif
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 3b63d1ce7fda..ee135e369a72 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -247,61 +247,6 @@ static inline unsigned long node_maxindex(const struct 
radix_tree_node *node)
        return shift_maxindex(node->shift);
 }
 
-static unsigned long rnext_index(unsigned long index,
-                               const struct radix_tree_node *node,
-                               unsigned long offset)
-{
-       return (index & ~node_maxindex(node)) + (offset << node->shift);
-}
-
-#ifndef __KERNEL__
-static void dump_ida_node(void *entry, unsigned long index)
-{
-       unsigned long i;
-
-       if (!entry)
-               return;
-
-       if (radix_tree_is_internal_node(entry)) {
-               struct radix_tree_node *node = entry_to_node(entry);
-
-               pr_debug("ida node: %p offset %d indices %lu-%lu parent %p free 
%lx shift %d count %d\n",
-                       node, node->offset, index * IDA_BITMAP_BITS,
-                       ((index | node_maxindex(node)) + 1) *
-                               IDA_BITMAP_BITS - 1,
-                       node->parent, node->tags[0][0], node->shift,
-                       node->count);
-               for (i = 0; i < RADIX_TREE_MAP_SIZE; i++)
-                       dump_ida_node(node->slots[i],
-                                       index | (i << node->shift));
-       } else if (xa_is_value(entry)) {
-               pr_debug("ida excp: %p offset %d indices %lu-%lu data %lx\n",
-                               entry, (int)(index & RADIX_TREE_MAP_MASK),
-                               index * IDA_BITMAP_BITS,
-                               index * IDA_BITMAP_BITS + BITS_PER_XA_VALUE,
-                               xa_to_value(entry));
-       } else {
-               struct ida_bitmap *bitmap = entry;
-
-               pr_debug("ida btmp: %p offset %d indices %lu-%lu data", bitmap,
-                               (int)(index & RADIX_TREE_MAP_MASK),
-                               index * IDA_BITMAP_BITS,
-                               (index + 1) * IDA_BITMAP_BITS - 1);
-               for (i = 0; i < IDA_BITMAP_LONGS; i++)
-                       pr_cont(" %lx", bitmap->bitmap[i]);
-               pr_cont("\n");
-       }
-}
-
-static void ida_dump(struct ida *ida)
-{
-       struct radix_tree_root *root = &ida->ida_rt;
-       pr_debug("ida: %p node %p free %d\n", ida, root->xa_head,
-                               root->xa_flags >> ROOT_TAG_SHIFT);
-       dump_ida_node(root->xa_head, 0);
-}
-#endif
-
 /*
  * This assumes that the caller has performed appropriate preallocation, and
  * that the caller has pinned this thread of control to the current CPU.
@@ -2083,77 +2028,6 @@ int ida_pre_get(struct ida *ida, gfp_t gfp)
 }
 EXPORT_SYMBOL(ida_pre_get);
 
-void __rcu **idr_get_free(struct radix_tree_root *root,
-                             struct radix_tree_iter *iter, gfp_t gfp,
-                             unsigned long max)
-{
-       struct radix_tree_node *node = NULL, *child;
-       void __rcu **slot = (void __rcu **)&root->xa_head;
-       unsigned long maxindex, start = iter->next_index;
-       unsigned int shift, offset = 0;
-
- grow:
-       shift = radix_tree_load_root(root, &child, &maxindex);
-       if (!radix_tree_tagged(root, XA_FREE_TAG))
-               start = max(start, maxindex + 1);
-       if (start > max)
-               return ERR_PTR(-ENOSPC);
-
-       if (start > maxindex) {
-               int error = radix_tree_extend(root, gfp, start, shift);
-               if (error < 0)
-                       return ERR_PTR(error);
-               shift = error;
-               child = rcu_dereference_raw(root->xa_head);
-       }
-
-       while (shift) {
-               shift -= RADIX_TREE_MAP_SHIFT;
-               if (child == NULL) {
-                       /* Have to add a child node.  */
-                       child = radix_tree_node_alloc(gfp, node, root, shift,
-                                                       offset, 0, 0);
-                       if (!child)
-                               return ERR_PTR(-ENOMEM);
-                       all_tag_set(child, XA_FREE_TAG);
-                       rcu_assign_pointer(*slot, node_to_entry(child));
-                       if (node)
-                               node->count++;
-               } else if (!radix_tree_is_internal_node(child))
-                       break;
-
-               node = entry_to_node(child);
-               offset = radix_tree_descend(node, &child, start);
-               if (!rtag_get(node, XA_FREE_TAG, offset)) {
-                       offset = radix_tree_find_next_bit(node, XA_FREE_TAG,
-                                                       offset + 1);
-                       start = rnext_index(start, node, offset);
-                       if (start > max)
-                               return ERR_PTR(-ENOSPC);
-                       while (offset == RADIX_TREE_MAP_SIZE) {
-                               offset = node->offset + 1;
-                               node = node->parent;
-                               if (!node)
-                                       goto grow;
-                               shift = node->shift;
-                       }
-                       child = rcu_dereference_raw(node->slots[offset]);
-               }
-               slot = &node->slots[offset];
-       }
-
-       iter->index = start;
-       if (node)
-               iter->next_index = 1 + min(max, (start | node_maxindex(node)));
-       else
-               iter->next_index = 1;
-       iter->node = node;
-       __set_iter_shift(iter, shift);
-       set_iter_tags(iter, node, offset, XA_FREE_TAG);
-
-       return slot;
-}
-
 static void
 radix_tree_node_ctor(void *arg)
 {
-- 
2.15.0

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