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radix-tree: rewrite gang lookup using iterator
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Rewrite radix_tree_gang_lookup_* functions using the new radix-tree
iterator.

Signed-off-by: Konstantin Khlebnikov <[email protected]>
Tested-by: Hugh Dickins <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@koct9i @torvalds
koct9i authored and torvalds committed Mar 29, 2012
1 parent 78c1d78 commit cebbd29
Showing 1 changed file with 33 additions and 258 deletions.
291 changes: 33 additions & 258 deletions lib/radix-tree.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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;
Expand Down Expand Up @@ -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
Expand All @@ -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;
Expand All @@ -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;
Expand Down

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