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#include <linux/slab.h>
#include <linux/gfp.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/ceph/string_table.h>
static DEFINE_SPINLOCK(string_tree_lock);
static struct rb_root string_tree = RB_ROOT;
struct ceph_string *ceph_find_or_create_string(const char* str, size_t len)
{
struct ceph_string *cs, *exist;
struct rb_node **p, *parent;
int ret;
exist = NULL;
spin_lock(&string_tree_lock);
p = &string_tree.rb_node;
while (*p) {
exist = rb_entry(*p, struct ceph_string, node);
ret = ceph_compare_string(exist, str, len);
if (ret > 0)
p = &(*p)->rb_left;
else if (ret < 0)
p = &(*p)->rb_right;
else
break;
exist = NULL;
}
if (exist && !kref_get_unless_zero(&exist->kref)) {
rb_erase(&exist->node, &string_tree);
RB_CLEAR_NODE(&exist->node);
exist = NULL;
}
spin_unlock(&string_tree_lock);
if (exist)
return exist;
cs = kmalloc(sizeof(*cs) + len + 1, GFP_NOFS);
if (!cs)
return NULL;
kref_init(&cs->kref);
cs->len = len;
memcpy(cs->str, str, len);
cs->str[len] = 0;
retry:
exist = NULL;
parent = NULL;
p = &string_tree.rb_node;
spin_lock(&string_tree_lock);
while (*p) {
parent = *p;
exist = rb_entry(*p, struct ceph_string, node);
ret = ceph_compare_string(exist, str, len);
if (ret > 0)
p = &(*p)->rb_left;
else if (ret < 0)
p = &(*p)->rb_right;
else
break;
exist = NULL;
}
ret = 0;
if (!exist) {
rb_link_node(&cs->node, parent, p);
rb_insert_color(&cs->node, &string_tree);
} else if (!kref_get_unless_zero(&exist->kref)) {
rb_erase(&exist->node, &string_tree);
RB_CLEAR_NODE(&exist->node);
ret = -EAGAIN;
}
spin_unlock(&string_tree_lock);
if (ret == -EAGAIN)
goto retry;
if (exist) {
kfree(cs);
cs = exist;
}
return cs;
}
EXPORT_SYMBOL(ceph_find_or_create_string);
static void ceph_free_string(struct rcu_head *head)
{
struct ceph_string *cs = container_of(head, struct ceph_string, rcu);
kfree(cs);
}
void ceph_release_string(struct kref *ref)
{
struct ceph_string *cs = container_of(ref, struct ceph_string, kref);
spin_lock(&string_tree_lock);
if (!RB_EMPTY_NODE(&cs->node)) {
rb_erase(&cs->node, &string_tree);
RB_CLEAR_NODE(&cs->node);
}
spin_unlock(&string_tree_lock);
call_rcu(&cs->rcu, ceph_free_string);
}
EXPORT_SYMBOL(ceph_release_string);
bool ceph_strings_empty(void)
{
return RB_EMPTY_ROOT(&string_tree);
}
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