/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _FS_CEPH_STRING_TABLE_H
#define _FS_CEPH_STRING_TABLE_H

#include <linux/types.h>
#include <linux/kref.h>
#include <linux/rbtree.h>
#include <linux/rcupdate.h>

struct ceph_string {
        struct kref kref;
        union {
                struct rb_node node;
                struct rcu_head rcu;
        };
        size_t len;
        char str[];
};

extern void ceph_release_string(struct kref *ref);
extern struct ceph_string *ceph_find_or_create_string(const char *str,
                                                      size_t len);
extern bool ceph_strings_empty(void);

static inline struct ceph_string *ceph_get_string(struct ceph_string *str)
{
        kref_get(&str->kref);
        return str;
}

static inline void ceph_put_string(struct ceph_string *str)
{
        if (!str)
                return;
        kref_put(&str->kref, ceph_release_string);
}

static inline int ceph_compare_string(struct ceph_string *cs,
                                      const char* str, size_t len)
{
        size_t cs_len = cs ? cs->len : 0;
        if (cs_len != len)
                return cs_len - len;
        if (len == 0)
                return 0;
        return strncmp(cs->str, str, len);
}

#define ceph_try_get_string(x)                                  \
({                                                              \
        struct ceph_string *___str;                             \
        rcu_read_lock();                                        \
        for (;;) {                                              \
                ___str = rcu_dereference(x);                    \
                if (!___str ||                                  \
                    kref_get_unless_zero(&___str->kref))        \
                        break;                                  \
        }                                                       \
        rcu_read_unlock();                                      \
        (___str);                                               \
})

#endif