include/linux/ceph/string_table.h

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