| 1 | |
| 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;
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| 10 |
|
| 11 | struct ceph_string *ceph_find_or_create_string(const char* str, size_t len)
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| 12 | {
|
| 13 | struct ceph_string *cs, *exist;
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| 14 | struct rb_node **p, *parent;
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| 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 |
|
| 49 | retry:
|
| 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);
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| 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 | }
|
| 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(&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);
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| 98 |
|
| 99 | kfree_rcu(cs, rcu);
|
| 100 | }
|
| 101 | EXPORT_SYMBOL(ceph_release_string);
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| 102 |
|
| 103 | bool ceph_strings_empty(void)
|
| 104 | {
|
| 105 | return RB_EMPTY_ROOT(&string_tree);
|
| 106 | }
|