radix-tree: rewrite gang lookup using iterator

Rewrite radix_tree_gang_lookup_* functions using the new radix-tree
iterator.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Tested-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 33 insertions, 258 deletions

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index fefa76e6ff96..86516f5588e3 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -968,57 +968,6 @@ unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
 }
 EXPORT_SYMBOL(radix_tree_prev_hole);
 
-static unsigned int
-__lookup(struct radix_tree_node *slot, void ***results, unsigned long *indices,
-        unsigned long index, unsigned int max_items, unsigned long *next_index)
-{
-        unsigned int nr_found = 0;
-        unsigned int shift, height;
-        unsigned long i;
-
-        height = slot->height;
-        if (height == 0)
-                goto out;
-        shift = (height-1) * RADIX_TREE_MAP_SHIFT;
-
-        for ( ; height > 1; height--) {
-                i = (index >> shift) & RADIX_TREE_MAP_MASK;
-                for (;;) {
-                        if (slot->slots[i] != NULL)
-                                break;
-                        index &= ~((1UL << shift) - 1);
-                        index += 1UL << shift;
-                        if (index == 0)
-                                goto out;       /* 32-bit wraparound */
-                        i++;
-                        if (i == RADIX_TREE_MAP_SIZE)
-                                goto out;
-                }
-
-                shift -= RADIX_TREE_MAP_SHIFT;
-                slot = rcu_dereference_raw(slot->slots[i]);
-                if (slot == NULL)
-                        goto out;
-        }
-
-        /* Bottom level: grab some items */
-        for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
-                if (slot->slots[i]) {
-                        results[nr_found] = &(slot->slots[i]);
-                        if (indices)
-                                indices[nr_found] = index;
-                        if (++nr_found == max_items) {
-                                index++;
-                                goto out;
-                        }
-                }
-                index++;
-        }
-out:
-        *next_index = index;
-        return nr_found;
-}
-
 /**
  *      radix_tree_gang_lookup - perform multiple lookup on a radix tree
  *      @root:          radix tree root
@@ -1042,48 +991,19 @@ unsigned int
 radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
                         unsigned long first_index, unsigned int max_items)
 {
-        unsigned long max_index;
-        struct radix_tree_node *node;
-        unsigned long cur_index = first_index;
-        unsigned int ret;
+        struct radix_tree_iter iter;
+        void **slot;
+        unsigned int ret = 0;
 
-        node = rcu_dereference_raw(root->rnode);
-        if (!node)
+        if (unlikely(!max_items))
                 return 0;
 
-        if (!radix_tree_is_indirect_ptr(node)) {
-                if (first_index > 0)
-                        return 0;
-                results[0] = node;
-                return 1;
-        }
-        node = indirect_to_ptr(node);
-
-        max_index = radix_tree_maxindex(node->height);
-
-        ret = 0;
-        while (ret < max_items) {
-                unsigned int nr_found, slots_found, i;
-                unsigned long next_index;       /* Index of next search */
-
-                if (cur_index > max_index)
-                        break;
-                slots_found = __lookup(node, (void ***)results + ret, NULL,
-                                cur_index, max_items - ret, &next_index);
-                nr_found = 0;
-                for (i = 0; i < slots_found; i++) {
-                        struct radix_tree_node *slot;
-                        slot = *(((void ***)results)[ret + i]);
-                        if (!slot)
-                                continue;
-                        results[ret + nr_found] =
-                                indirect_to_ptr(rcu_dereference_raw(slot));
-                        nr_found++;
-                }
-                ret += nr_found;
-                if (next_index == 0)
+        radix_tree_for_each_slot(slot, root, &iter, first_index) {
+                results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
+                if (!results[ret])
+                        continue;
+                if (++ret == max_items)
                         break;
-                cur_index = next_index;
         }
 
         return ret;
@@ -1113,112 +1033,25 @@ radix_tree_gang_lookup_slot(struct radix_tree_root *root,
                         void ***results, unsigned long *indices,
                         unsigned long first_index, unsigned int max_items)
 {
-        unsigned long max_index;
-        struct radix_tree_node *node;
-        unsigned long cur_index = first_index;
-        unsigned int ret;
+        struct radix_tree_iter iter;
+        void **slot;
+        unsigned int ret = 0;
 
-        node = rcu_dereference_raw(root->rnode);
-        if (!node)
+        if (unlikely(!max_items))
                 return 0;
 
-        if (!radix_tree_is_indirect_ptr(node)) {
-                if (first_index > 0)
-                        return 0;
-                results[0] = (void **)&root->rnode;
+        radix_tree_for_each_slot(slot, root, &iter, first_index) {
+                results[ret] = slot;
                 if (indices)
-                        indices[0] = 0;
-                return 1;
-        }
-        node = indirect_to_ptr(node);
-
-        max_index = radix_tree_maxindex(node->height);
-
-        ret = 0;
-        while (ret < max_items) {
-                unsigned int slots_found;
-                unsigned long next_index;       /* Index of next search */
-
-                if (cur_index > max_index)
+                        indices[ret] = iter.index;
+                if (++ret == max_items)
                         break;
-                slots_found = __lookup(node, results + ret,
-                                indices ? indices + ret : NULL,
-                                cur_index, max_items - ret, &next_index);
-                ret += slots_found;
-                if (next_index == 0)
-                        break;
-                cur_index = next_index;
         }
 
         return ret;
 }
 EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
 
-/*
- * FIXME: the two tag_get()s here should use find_next_bit() instead of
- * open-coding the search.
- */
-static unsigned int
-__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index,
-        unsigned int max_items, unsigned long *next_index, unsigned int tag)
-{
-        unsigned int nr_found = 0;
-        unsigned int shift, height;
-
-        height = slot->height;
-        if (height == 0)
-                goto out;
-        shift = (height-1) * RADIX_TREE_MAP_SHIFT;
-
-        while (height > 0) {
-                unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ;
-
-                for (;;) {
-                        if (tag_get(slot, tag, i))
-                                break;
-                        index &= ~((1UL << shift) - 1);
-                        index += 1UL << shift;
-                        if (index == 0)
-                                goto out;       /* 32-bit wraparound */
-                        i++;
-                        if (i == RADIX_TREE_MAP_SIZE)
-                                goto out;
-                }
-                height--;
-                if (height == 0) {      /* Bottom level: grab some items */
-                        unsigned long j = index & RADIX_TREE_MAP_MASK;
-
-                        for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
-                                index++;
-                                if (!tag_get(slot, tag, j))
-                                        continue;
-                                /*
-                                 * Even though the tag was found set, we need to
-                                 * recheck that we have a non-NULL node, because
-                                 * if this lookup is lockless, it may have been
-                                 * subsequently deleted.
-                                 *
-                                 * Similar care must be taken in any place that
-                                 * lookup ->slots[x] without a lock (ie. can't
-                                 * rely on its value remaining the same).
-                                 */
-                                if (slot->slots[j]) {
-                                        results[nr_found++] = &(slot->slots[j]);
-                                        if (nr_found == max_items)
-                                                goto out;
-                                }
-                        }
-                }
-                shift -= RADIX_TREE_MAP_SHIFT;
-                slot = rcu_dereference_raw(slot->slots[i]);
-                if (slot == NULL)
-                        break;
-        }
-out:
-        *next_index = index;
-        return nr_found;
-}
-
 /**
  *      radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
  *                                   based on a tag
@@ -1237,52 +1070,19 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
                 unsigned long first_index, unsigned int max_items,
                 unsigned int tag)
 {
-        struct radix_tree_node *node;
-        unsigned long max_index;
-        unsigned long cur_index = first_index;
-        unsigned int ret;
+        struct radix_tree_iter iter;
+        void **slot;
+        unsigned int ret = 0;
 
-        /* check the root's tag bit */
-        if (!root_tag_get(root, tag))
+        if (unlikely(!max_items))
                 return 0;
 
-        node = rcu_dereference_raw(root->rnode);
-        if (!node)
-                return 0;
-
-        if (!radix_tree_is_indirect_ptr(node)) {
-                if (first_index > 0)
-                        return 0;
-                results[0] = node;
-                return 1;
-        }
-        node = indirect_to_ptr(node);
-
-        max_index = radix_tree_maxindex(node->height);
-
-        ret = 0;
-        while (ret < max_items) {
-                unsigned int nr_found, slots_found, i;
-                unsigned long next_index;       /* Index of next search */
-
-                if (cur_index > max_index)
-                        break;
-                slots_found = __lookup_tag(node, (void ***)results + ret,
-                                cur_index, max_items - ret, &next_index, tag);
-                nr_found = 0;
-                for (i = 0; i < slots_found; i++) {
-                        struct radix_tree_node *slot;
-                        slot = *(((void ***)results)[ret + i]);
-                        if (!slot)
-                                continue;
-                        results[ret + nr_found] =
-                                indirect_to_ptr(rcu_dereference_raw(slot));
-                        nr_found++;
-                }
-                ret += nr_found;
-                if (next_index == 0)
+        radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
+                results[ret] = indirect_to_ptr(rcu_dereference_raw(*slot));
+                if (!results[ret])
+                        continue;
+                if (++ret == max_items)
                         break;
-                cur_index = next_index;
         }
 
         return ret;
@@ -1307,42 +1107,17 @@ radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
                 unsigned long first_index, unsigned int max_items,
                 unsigned int tag)
 {
-        struct radix_tree_node *node;
-        unsigned long max_index;
-        unsigned long cur_index = first_index;
-        unsigned int ret;
+        struct radix_tree_iter iter;
+        void **slot;
+        unsigned int ret = 0;
 
-        /* check the root's tag bit */
-        if (!root_tag_get(root, tag))
-                return 0;
-
-        node = rcu_dereference_raw(root->rnode);
-        if (!node)
+        if (unlikely(!max_items))
                 return 0;
 
-        if (!radix_tree_is_indirect_ptr(node)) {
-                if (first_index > 0)
-                        return 0;
-                results[0] = (void **)&root->rnode;
-                return 1;
-        }
-        node = indirect_to_ptr(node);
-
-        max_index = radix_tree_maxindex(node->height);
-
-        ret = 0;
-        while (ret < max_items) {
-                unsigned int slots_found;
-                unsigned long next_index;       /* Index of next search */
-
-                if (cur_index > max_index)
-                        break;
-                slots_found = __lookup_tag(node, results + ret,
-                                cur_index, max_items - ret, &next_index, tag);
-                ret += slots_found;
-                if (next_index == 0)
+        radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) {
+                results[ret] = slot;
+                if (++ret == max_items)
                         break;
-                cur_index = next_index;
         }
 
         return ret;