1// SPDX-License-Identifier: GPL-2.0
2#include <linux/slab.h>
3#include <linux/gfp.h>
4#include <linux/string.h>
5#include <linux/spinlock.h>
6#include <linux/ceph/string_table.h>
7
8static DEFINE_SPINLOCK(string_tree_lock);
9static struct rb_root string_tree = RB_ROOT;
10
11struct ceph_string *ceph_find_or_create_string(const char* str, size_t len)
12{
13	struct ceph_string *cs, *exist;
14	struct rb_node **p, *parent;
15	int ret;
16
17	exist = NULL;
18	spin_lock(&string_tree_lock);
19	p = &string_tree.rb_node;
20	while (*p) {
21		exist = rb_entry(*p, struct ceph_string, node);
22		ret = ceph_compare_string(exist, str, len);
23		if (ret > 0)
24			p = &(*p)->rb_left;
25		else if (ret < 0)
26			p = &(*p)->rb_right;
27		else
28			break;
29		exist = NULL;
30	}
31	if (exist && !kref_get_unless_zero(&exist->kref)) {
32		rb_erase(&exist->node, &string_tree);
33		RB_CLEAR_NODE(&exist->node);
34		exist = NULL;
35	}
36	spin_unlock(&string_tree_lock);
37	if (exist)
38		return exist;
39
40	cs = kmalloc(sizeof(*cs) + len + 1, GFP_NOFS);
41	if (!cs)
42		return NULL;
43
44	kref_init(&cs->kref);
45	cs->len = len;
46	memcpy(cs->str, str, len);
47	cs->str[len] = 0;
48
49retry:
50	exist = NULL;
51	parent = NULL;
52	p = &string_tree.rb_node;
53	spin_lock(&string_tree_lock);
54	while (*p) {
55		parent = *p;
56		exist = rb_entry(*p, struct ceph_string, node);
57		ret = ceph_compare_string(exist, str, len);
58		if (ret > 0)
59			p = &(*p)->rb_left;
60		else if (ret < 0)
61			p = &(*p)->rb_right;
62		else
63			break;
64		exist = NULL;
65	}
66	ret = 0;
67	if (!exist) {
68		rb_link_node(&cs->node, parent, p);
69		rb_insert_color(&cs->node, &string_tree);
70	} else if (!kref_get_unless_zero(&exist->kref)) {
71		rb_erase(&exist->node, &string_tree);
72		RB_CLEAR_NODE(&exist->node);
73		ret = -EAGAIN;
74	}
75	spin_unlock(&string_tree_lock);
76	if (ret == -EAGAIN)
77		goto retry;
78
79	if (exist) {
80		kfree(cs);
81		cs = exist;
82	}
83
84	return cs;
85}
86EXPORT_SYMBOL(ceph_find_or_create_string);
87
88void ceph_release_string(struct kref *ref)
89{
90	struct ceph_string *cs = container_of(ref, struct ceph_string, kref);
91
92	spin_lock(&string_tree_lock);
93	if (!RB_EMPTY_NODE(&cs->node)) {
94		rb_erase(&cs->node, &string_tree);
95		RB_CLEAR_NODE(&cs->node);
96	}
97	spin_unlock(&string_tree_lock);
98
99	kfree_rcu(cs, rcu);
100}
101EXPORT_SYMBOL(ceph_release_string);
102
103bool ceph_strings_empty(void)
104{
105	return RB_EMPTY_ROOT(&string_tree);
106}
107