include/linux/ceph/string_table.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _FS_CEPH_STRING_TABLE_H
   3 #define _FS_CEPH_STRING_TABLE_H
   4
   5 #include <linux/types.h>
   6 #include <linux/kref.h>
   7 #include <linux/rbtree.h>
   8 #include <linux/rcupdate.h>
   9
  10 struct ceph_string {
  11         struct kref kref;
  12         union {
  13                 struct rb_node node;
  14                 struct rcu_head rcu;
  15         };
  16         size_t len;
  17         char str[];
  18 };
  19
  20 extern void ceph_release_string(struct kref *ref);
  21 extern struct ceph_string *ceph_find_or_create_string(const char *str,
  22                                                       size_t len);
  23 extern bool ceph_strings_empty(void);
  24
  25 static inline struct ceph_string *ceph_get_string(struct ceph_string *str)
  26 {
  27         kref_get(&str->kref);
  28         return str;
  29 }
  30
  31 static inline void ceph_put_string(struct ceph_string *str)
  32 {
  33         if (!str)
  34                 return;
  35         kref_put(&str->kref, ceph_release_string);
  36 }
  37
  38 static inline int ceph_compare_string(struct ceph_string *cs,
  39                                       const char* str, size_t len)
  40 {
  41         size_t cs_len = cs ? cs->len : 0;
  42         if (cs_len != len)
  43                 return cs_len - len;
  44         if (len == 0)
  45                 return 0;
  46         return strncmp(cs->str, str, len);
  47 }
  48
  49 #define ceph_try_get_string(x)                                  \
  50 ({                                                              \
  51         struct ceph_string *___str;                             \
  52         rcu_read_lock();                                        \
  53         for (;;) {                                              \
  54                 ___str = rcu_dereference(x);                    \
  55                 if (!___str ||                                  \
  56                     kref_get_unless_zero(&___str->kref))        \
  57                         break;                                  \
  58         }                                                       \
  59         rcu_read_unlock();                                      \
  60         (___str);                                               \
  61 })
  62
  63 #endif