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[PATCH] radix-tree: direct data
The ability to have height 0 radix trees (a direct pointer to the data item rather than going through a full node->slot) quietly disappeared with old-2.6-bkcvs commit ffee171812d51652f9ba284302d9e5c5cc14bdfd. On 64-bit machines this causes nearly 600 bytes to be used for every <= 4K file in pagecache. Re-introduce this feature, root tags stored in spare ->gfp_mask bits. Simplify radix_tree_delete's complex tag clearing arrangement (which would become even more complex) by just falling back to tag clearing functions (the pagecache radix-tree never uses this path anyway, so the icache savings will mean it's actually a speedup). On my 4GB G5, this saves 8MB RAM per kernel kernel source+object tree in pagecache. Pagecache lookup, insertion, and removal speed for small files will also be improved. This makes RCU radix tree harder, but it's worth it. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin
Linus Torvalds
parent
929f97276b
commit
612d6c19db
@ -23,6 +23,9 @@
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#include <linux/preempt.h>
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#include <linux/types.h>
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#define RADIX_TREE_MAX_TAGS 2
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/* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */
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struct radix_tree_root {
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unsigned int height;
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gfp_t gfp_mask;
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@ -45,8 +48,6 @@ do { \
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(root)->rnode = NULL; \
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} while (0)
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#define RADIX_TREE_MAX_TAGS 2
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int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
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void *radix_tree_lookup(struct radix_tree_root *, unsigned long);
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void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long);
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192
lib/radix-tree.c
192
lib/radix-tree.c
@ -74,6 +74,11 @@ struct radix_tree_preload {
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};
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DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
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static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
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{
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return root->gfp_mask & __GFP_BITS_MASK;
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}
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/*
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* This assumes that the caller has performed appropriate preallocation, and
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* that the caller has pinned this thread of control to the current CPU.
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@ -82,9 +87,10 @@ static struct radix_tree_node *
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radix_tree_node_alloc(struct radix_tree_root *root)
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{
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struct radix_tree_node *ret;
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gfp_t gfp_mask = root_gfp_mask(root);
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ret = kmem_cache_alloc(radix_tree_node_cachep, root->gfp_mask);
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if (ret == NULL && !(root->gfp_mask & __GFP_WAIT)) {
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ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
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if (ret == NULL && !(gfp_mask & __GFP_WAIT)) {
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struct radix_tree_preload *rtp;
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rtp = &__get_cpu_var(radix_tree_preloads);
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@ -152,6 +158,27 @@ static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
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return test_bit(offset, node->tags[tag]);
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}
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static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
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{
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root->gfp_mask |= (1 << (tag + __GFP_BITS_SHIFT));
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}
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static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
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{
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root->gfp_mask &= ~(1 << (tag + __GFP_BITS_SHIFT));
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}
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static inline void root_tag_clear_all(struct radix_tree_root *root)
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{
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root->gfp_mask &= __GFP_BITS_MASK;
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}
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static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
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{
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return root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
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}
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/*
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* Returns 1 if any slot in the node has this tag set.
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* Otherwise returns 0.
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@ -182,7 +209,6 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
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{
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struct radix_tree_node *node;
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unsigned int height;
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char tags[RADIX_TREE_MAX_TAGS];
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int tag;
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/* Figure out what the height should be. */
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@ -195,16 +221,6 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
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goto out;
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}
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/*
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* Prepare the tag status of the top-level node for propagation
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* into the newly-pushed top-level node(s)
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*/
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for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
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tags[tag] = 0;
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if (any_tag_set(root->rnode, tag))
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tags[tag] = 1;
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}
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do {
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if (!(node = radix_tree_node_alloc(root)))
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return -ENOMEM;
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@ -214,7 +230,7 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
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/* Propagate the aggregated tag info into the new root */
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for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
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if (tags[tag])
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if (root_tag_get(root, tag))
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tag_set(node, tag, 0);
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}
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@ -243,8 +259,7 @@ int radix_tree_insert(struct radix_tree_root *root,
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int error;
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/* Make sure the tree is high enough. */
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if ((!index && !root->rnode) ||
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index > radix_tree_maxindex(root->height)) {
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if (index > radix_tree_maxindex(root->height)) {
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error = radix_tree_extend(root, index);
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if (error)
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return error;
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@ -255,7 +270,7 @@ int radix_tree_insert(struct radix_tree_root *root,
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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offset = 0; /* uninitialised var warning */
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do {
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while (height > 0) {
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if (slot == NULL) {
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/* Have to add a child node. */
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if (!(slot = radix_tree_node_alloc(root)))
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@ -273,16 +288,21 @@ int radix_tree_insert(struct radix_tree_root *root,
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slot = node->slots[offset];
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shift -= RADIX_TREE_MAP_SHIFT;
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height--;
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} while (height > 0);
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}
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if (slot != NULL)
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return -EEXIST;
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BUG_ON(!node);
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node->count++;
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node->slots[offset] = item;
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BUG_ON(tag_get(node, 0, offset));
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BUG_ON(tag_get(node, 1, offset));
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if (node) {
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node->count++;
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node->slots[offset] = item;
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BUG_ON(tag_get(node, 0, offset));
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BUG_ON(tag_get(node, 1, offset));
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} else {
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root->rnode = item;
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BUG_ON(root_tag_get(root, 0));
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BUG_ON(root_tag_get(root, 1));
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}
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return 0;
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}
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@ -295,9 +315,13 @@ static inline void **__lookup_slot(struct radix_tree_root *root,
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struct radix_tree_node **slot;
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height = root->height;
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if (index > radix_tree_maxindex(height))
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return NULL;
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if (height == 0 && root->rnode)
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return (void **)&root->rnode;
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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slot = &root->rnode;
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@ -368,8 +392,8 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
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if (index > radix_tree_maxindex(height))
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return NULL;
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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slot = root->rnode;
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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while (height > 0) {
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int offset;
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@ -383,6 +407,10 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
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height--;
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}
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/* set the root's tag bit */
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if (slot && !root_tag_get(root, tag))
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root_tag_set(root, tag);
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return slot;
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}
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EXPORT_SYMBOL(radix_tree_tag_set);
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@ -405,9 +433,8 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
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unsigned long index, unsigned int tag)
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{
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struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
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struct radix_tree_node *slot;
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struct radix_tree_node *slot = NULL;
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unsigned int height, shift;
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void *ret = NULL;
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height = root->height;
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if (index > radix_tree_maxindex(height))
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@ -432,20 +459,24 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
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height--;
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}
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ret = slot;
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if (ret == NULL)
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if (slot == NULL)
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goto out;
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do {
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while (pathp->node) {
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if (!tag_get(pathp->node, tag, pathp->offset))
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goto out;
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tag_clear(pathp->node, tag, pathp->offset);
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if (any_tag_set(pathp->node, tag))
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goto out;
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pathp--;
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} while (pathp->node);
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}
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/* clear the root's tag bit */
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if (root_tag_get(root, tag))
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root_tag_clear(root, tag);
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out:
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return ret;
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return slot;
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}
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EXPORT_SYMBOL(radix_tree_tag_clear);
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@ -458,9 +489,8 @@ EXPORT_SYMBOL(radix_tree_tag_clear);
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*
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* Return values:
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*
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* 0: tag not present
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* 1: tag present, set
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* -1: tag present, unset
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* 0: tag not present or not set
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* 1: tag set
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*/
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int radix_tree_tag_get(struct radix_tree_root *root,
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unsigned long index, unsigned int tag)
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@ -473,6 +503,13 @@ int radix_tree_tag_get(struct radix_tree_root *root,
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if (index > radix_tree_maxindex(height))
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return 0;
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/* check the root's tag bit */
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if (!root_tag_get(root, tag))
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return 0;
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if (height == 0)
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return 1;
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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slot = root->rnode;
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@ -494,7 +531,7 @@ int radix_tree_tag_get(struct radix_tree_root *root,
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int ret = tag_get(slot, tag, offset);
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BUG_ON(ret && saw_unset_tag);
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return ret ? 1 : -1;
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return ret;
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}
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slot = slot->slots[offset];
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shift -= RADIX_TREE_MAP_SHIFT;
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@ -514,8 +551,11 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index,
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unsigned long i;
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height = root->height;
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if (height == 0)
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if (height == 0) {
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if (root->rnode && index == 0)
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results[nr_found++] = root->rnode;
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goto out;
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}
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shift = (height-1) * RADIX_TREE_MAP_SHIFT;
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slot = root->rnode;
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@ -603,10 +643,16 @@ __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
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unsigned int height = root->height;
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struct radix_tree_node *slot;
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if (height == 0) {
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if (root->rnode && index == 0)
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results[nr_found++] = root->rnode;
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goto out;
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}
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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slot = root->rnode;
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while (height > 0) {
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do {
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unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
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for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
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@ -637,7 +683,7 @@ __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
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}
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shift -= RADIX_TREE_MAP_SHIFT;
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slot = slot->slots[i];
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}
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} while (height > 0);
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out:
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*next_index = index;
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return nr_found;
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@ -665,6 +711,10 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
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unsigned long cur_index = first_index;
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unsigned int ret = 0;
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/* check the root's tag bit */
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if (!root_tag_get(root, tag))
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return 0;
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while (ret < max_items) {
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unsigned int nr_found;
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unsigned long next_index; /* Index of next search */
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@ -689,7 +739,7 @@ EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
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static inline void radix_tree_shrink(struct radix_tree_root *root)
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{
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/* try to shrink tree height */
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while (root->height > 1 &&
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while (root->height > 0 &&
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root->rnode->count == 1 &&
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root->rnode->slots[0]) {
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struct radix_tree_node *to_free = root->rnode;
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@ -717,12 +767,8 @@ static inline void radix_tree_shrink(struct radix_tree_root *root)
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void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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{
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struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
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struct radix_tree_path *orig_pathp;
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struct radix_tree_node *slot;
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struct radix_tree_node *slot = NULL;
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unsigned int height, shift;
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void *ret = NULL;
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char tags[RADIX_TREE_MAX_TAGS];
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int nr_cleared_tags;
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int tag;
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int offset;
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@ -730,11 +776,17 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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if (index > radix_tree_maxindex(height))
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goto out;
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slot = root->rnode;
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if (height == 0 && root->rnode) {
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root_tag_clear_all(root);
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root->rnode = NULL;
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goto out;
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}
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
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pathp->node = NULL;
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slot = root->rnode;
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for ( ; height > 0; height--) {
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do {
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if (slot == NULL)
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goto out;
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@ -744,44 +796,22 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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pathp->node = slot;
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slot = slot->slots[offset];
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shift -= RADIX_TREE_MAP_SHIFT;
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}
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height--;
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} while (height > 0);
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ret = slot;
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if (ret == NULL)
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if (slot == NULL)
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goto out;
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orig_pathp = pathp;
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/*
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* Clear all tags associated with the just-deleted item
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*/
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nr_cleared_tags = 0;
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for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
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tags[tag] = 1;
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if (tag_get(pathp->node, tag, pathp->offset)) {
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tag_clear(pathp->node, tag, pathp->offset);
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if (!any_tag_set(pathp->node, tag)) {
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tags[tag] = 0;
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nr_cleared_tags++;
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}
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}
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}
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for (pathp--; nr_cleared_tags && pathp->node; pathp--) {
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for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
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if (tags[tag])
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continue;
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tag_clear(pathp->node, tag, pathp->offset);
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if (any_tag_set(pathp->node, tag)) {
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tags[tag] = 1;
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nr_cleared_tags--;
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}
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}
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if (tag_get(pathp->node, tag, pathp->offset))
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radix_tree_tag_clear(root, index, tag);
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}
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/* Now free the nodes we do not need anymore */
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for (pathp = orig_pathp; pathp->node; pathp--) {
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while (pathp->node) {
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pathp->node->slots[pathp->offset] = NULL;
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pathp->node->count--;
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@ -793,11 +823,15 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
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/* Node with zero slots in use so free it */
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radix_tree_node_free(pathp->node);
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pathp--;
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}
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root->rnode = NULL;
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root_tag_clear_all(root);
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root->height = 0;
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root->rnode = NULL;
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out:
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return ret;
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return slot;
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}
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EXPORT_SYMBOL(radix_tree_delete);
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@ -808,11 +842,7 @@ EXPORT_SYMBOL(radix_tree_delete);
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*/
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int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
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{
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struct radix_tree_node *rnode;
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rnode = root->rnode;
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if (!rnode)
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return 0;
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return any_tag_set(rnode, tag);
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return root_tag_get(root, tag);
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}
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EXPORT_SYMBOL(radix_tree_tagged);
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