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 | |
8 | static DEFINE_SPINLOCK(string_tree_lock); |
9 | static struct rb_root string_tree = RB_ROOT; |
10 | |
11 | struct 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(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(cs: 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(kref: &exist->kref)) { |
32 | rb_erase(&exist->node, &string_tree); |
33 | RB_CLEAR_NODE(&exist->node); |
34 | exist = NULL; |
35 | } |
36 | spin_unlock(lock: &string_tree_lock); |
37 | if (exist) |
38 | return exist; |
39 | |
40 | cs = kmalloc(size: sizeof(*cs) + len + 1, GFP_NOFS); |
41 | if (!cs) |
42 | return NULL; |
43 | |
44 | kref_init(kref: &cs->kref); |
45 | cs->len = len; |
46 | memcpy(cs->str, str, len); |
47 | cs->str[len] = 0; |
48 | |
49 | retry: |
50 | exist = NULL; |
51 | parent = NULL; |
52 | p = &string_tree.rb_node; |
53 | spin_lock(lock: &string_tree_lock); |
54 | while (*p) { |
55 | parent = *p; |
56 | exist = rb_entry(*p, struct ceph_string, node); |
57 | ret = ceph_compare_string(cs: 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(node: &cs->node, parent, rb_link: p); |
69 | rb_insert_color(&cs->node, &string_tree); |
70 | } else if (!kref_get_unless_zero(kref: &exist->kref)) { |
71 | rb_erase(&exist->node, &string_tree); |
72 | RB_CLEAR_NODE(&exist->node); |
73 | ret = -EAGAIN; |
74 | } |
75 | spin_unlock(lock: &string_tree_lock); |
76 | if (ret == -EAGAIN) |
77 | goto retry; |
78 | |
79 | if (exist) { |
80 | kfree(objp: cs); |
81 | cs = exist; |
82 | } |
83 | |
84 | return cs; |
85 | } |
86 | EXPORT_SYMBOL(ceph_find_or_create_string); |
87 | |
88 | void ceph_release_string(struct kref *ref) |
89 | { |
90 | struct ceph_string *cs = container_of(ref, struct ceph_string, kref); |
91 | |
92 | spin_lock(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(lock: &string_tree_lock); |
98 | |
99 | kfree_rcu(cs, rcu); |
100 | } |
101 | EXPORT_SYMBOL(ceph_release_string); |
102 | |
103 | bool ceph_strings_empty(void) |
104 | { |
105 | return RB_EMPTY_ROOT(&string_tree); |
106 | } |
107 | |