/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (c) 2022 Paulo Alcantara <palcantara@suse.de>
 */

#ifndef _CIFS_DFS_H
#define _CIFS_DFS_H

#include "cifsglob.h"
#include "cifsproto.h"
#include "fs_context.h"
#include "dfs_cache.h"
#include "cifs_unicode.h"
#include <linux/namei.h>
#include <linux/errno.h>

#define DFS_INTERLINK(v) \
        (((v) & DFSREF_REFERRAL_SERVER) && !((v) & DFSREF_STORAGE_SERVER))

struct dfs_ref {
        char *path;
        char *full_path;
        struct cifs_ses *ses;
        struct dfs_cache_tgt_list tl;
        struct dfs_cache_tgt_iterator *tit;
};

struct dfs_ref_walk {
        struct cifs_mount_ctx   *mnt_ctx;
        struct dfs_ref          *ref;
        struct dfs_ref          refs[MAX_NESTED_LINKS];
};

#define ref_walk_start(w)       ((w)->refs)
#define ref_walk_end(w) (&(w)->refs[ARRAY_SIZE((w)->refs) - 1])
#define ref_walk_cur(w) ((w)->ref)
#define ref_walk_descend(w)     (--ref_walk_cur(w) >= ref_walk_start(w))

#define ref_walk_tit(w) (ref_walk_cur(w)->tit)
#define ref_walk_path(w)        (ref_walk_cur(w)->path)
#define ref_walk_fpath(w)       (ref_walk_cur(w)->full_path)
#define ref_walk_tl(w)          (&ref_walk_cur(w)->tl)
#define ref_walk_ses(w) (ref_walk_cur(w)->ses)

static inline struct dfs_ref_walk *ref_walk_alloc(void)
{
        struct dfs_ref_walk *rw;

        rw = kmalloc_obj(*rw);
        if (!rw)
                return ERR_PTR(-ENOMEM);
        return rw;
}

static inline void ref_walk_init(struct dfs_ref_walk *rw,
                                 struct cifs_mount_ctx *mnt_ctx)
{
        memset(rw, 0, sizeof(*rw));
        rw->mnt_ctx = mnt_ctx;
        ref_walk_cur(rw) = ref_walk_start(rw);
}

static inline void __ref_walk_free(struct dfs_ref *ref)
{
        kfree(ref->path);
        kfree(ref->full_path);
        dfs_cache_free_tgts(&ref->tl);
        if (ref->ses)
                cifs_put_smb_ses(ref->ses);
        memset(ref, 0, sizeof(*ref));
}

static inline void ref_walk_free(struct dfs_ref_walk *rw)
{
        struct dfs_ref *ref;

        if (!rw)
                return;

        for (ref = ref_walk_start(rw); ref <= ref_walk_end(rw); ref++)
                __ref_walk_free(ref);
        kfree(rw);
}

static inline int ref_walk_advance(struct dfs_ref_walk *rw)
{
        struct dfs_ref *ref = ref_walk_cur(rw) + 1;

        if (ref > ref_walk_end(rw))
                return -ELOOP;
        __ref_walk_free(ref);
        ref_walk_cur(rw) = ref;
        return 0;
}

static inline struct dfs_cache_tgt_iterator *
ref_walk_next_tgt(struct dfs_ref_walk *rw)
{
        struct dfs_ref *ref = ref_walk_cur(rw);
        struct dfs_cache_tgt_iterator *tit;

        if (IS_ERR(ref->tit))
                return NULL;

        if (!ref->tit)
                tit = dfs_cache_get_tgt_iterator(&ref->tl);
        else
                tit = dfs_cache_get_next_tgt(&ref->tl, ref->tit);

        if (!tit) {
                ref->tit = ERR_PTR(-ENOENT);
                return NULL;
        }
        ref->tit = tit;
        return ref->tit;
}

static inline int ref_walk_get_tgt(struct dfs_ref_walk *rw,
                                   struct dfs_info3_param *tgt)
{
        zfree_dfs_info_param(tgt);
        return dfs_cache_get_tgt_referral(ref_walk_path(rw) + 1,
                                          ref_walk_tit(rw), tgt);
}

static inline void ref_walk_set_tgt_hint(struct dfs_ref_walk *rw)
{
        dfs_cache_noreq_update_tgthint(ref_walk_path(rw) + 1,
                                       ref_walk_tit(rw));
}

static inline void ref_walk_set_tcon(struct dfs_ref_walk *rw,
                                     struct cifs_tcon *tcon)
{
        struct dfs_ref *ref = ref_walk_start(rw);

        for (; ref <= ref_walk_cur(rw); ref++) {
                if (WARN_ON_ONCE(!ref->ses))
                        continue;
                list_add(&ref->ses->dlist, &tcon->dfs_ses_list);
                ref->ses = NULL;
        }
}

static inline void ref_walk_mark_end(struct dfs_ref_walk *rw)
{
        struct dfs_ref *ref = ref_walk_cur(rw) - 1;

        WARN_ON_ONCE(ref < ref_walk_start(rw));
        dfs_cache_noreq_update_tgthint(ref->path + 1, ref->tit);
        ref->tit = ERR_PTR(-ENOENT); /* end marker */
}

int dfs_parse_target_referral(const char *full_path,
                              const struct dfs_info3_param *ref,
                              struct smb3_fs_context *ctx);
int dfs_mount_share(struct cifs_mount_ctx *mnt_ctx);

static inline char *dfs_get_path(struct cifs_sb_info *cifs_sb, const char *path)
{
        return dfs_cache_canonical_path(path, cifs_sb->local_nls, cifs_remap(cifs_sb));
}

static inline int dfs_get_referral(struct cifs_mount_ctx *mnt_ctx,
                                   const char *path,
                                   struct dfs_cache_tgt_list *tl)
{
        struct smb3_fs_context *ctx = mnt_ctx->fs_ctx;
        struct cifs_sb_info *cifs_sb = mnt_ctx->cifs_sb;
        struct cifs_ses *rses = ctx->dfs_root_ses ?: mnt_ctx->ses;

        return dfs_cache_find(mnt_ctx->xid, rses, cifs_sb->local_nls,
                              cifs_remap(cifs_sb), path, NULL, tl);
}

/*
 * cifs_get_smb_ses() already guarantees an active reference of
 * @ses->dfs_root_ses when a new session is created, so we need to put extra
 * references of all DFS root sessions that were used across the mount process
 * in dfs_mount_share().
 */
static inline void dfs_put_root_smb_sessions(struct list_head *head)
{
        struct cifs_ses *ses, *n;

        list_for_each_entry_safe(ses, n, head, dlist) {
                list_del_init(&ses->dlist);
                cifs_put_smb_ses(ses);
        }
}

static inline const char *dfs_ses_refpath(struct cifs_ses *ses)
{
        const char *path = ses->server->leaf_fullpath;

        return path ? path + 1 : ERR_PTR(-ENOENT);
}

#endif /* _CIFS_DFS_H */