// SPDX-License-Identifier: GPL-2.0
/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/lustre/llite/llite_nfs.c
 *
 * NFS export of Lustre Light File System
 *
 * Author: Yury Umanets <umka@clusterfs.com>
 * Author: Huang Hua <huanghua@clusterfs.com>
 */

#define DEBUG_SUBSYSTEM S_LLITE
#include "llite_internal.h"
#include <linux/exportfs.h>

__u32 get_uuid2int(const char *name, int len)
{
        __u32 key0 = 0x12a3fe2d, key1 = 0x37abe8f9;

        while (len--) {
                __u32 key = key1 + (key0 ^ (*name++ * 7152373));

                if (key & 0x80000000)
                        key -= 0x7fffffff;
                key1 = key0;
                key0 = key;
        }
        return (key0 << 1);
}

void get_uuid2fsid(const char *name, int len, __kernel_fsid_t *fsid)
{
        __u64 key = 0, key0 = 0x12a3fe2d, key1 = 0x37abe8f9;

        while (len--) {
                key = key1 + (key0 ^ (*name++ * 7152373));
                if (key & 0x8000000000000000ULL)
                        key -= 0x7fffffffffffffffULL;
                key1 = key0;
                key0 = key;
        }

        fsid->val[0] = key;
        fsid->val[1] = key >> 32;
}

struct inode *search_inode_for_lustre(struct super_block *sb,
                                      const struct lu_fid *fid)
{
        struct ll_sb_info     *sbi = ll_s2sbi(sb);
        struct ptlrpc_request *req = NULL;
        struct inode      *inode = NULL;
        int                eadatalen = 0;
        unsigned long         hash = cl_fid_build_ino(fid,
                                                      ll_need_32bit_api(sbi));
        struct  md_op_data    *op_data;
        int                rc;

        CDEBUG(D_INFO, "searching inode for:(%lu," DFID ")\n", hash, PFID(fid));

        inode = ilookup5(sb, hash, ll_test_inode_by_fid, (void *)fid);
        if (inode)
                return inode;

        rc = ll_get_default_mdsize(sbi, &eadatalen);
        if (rc)
                return ERR_PTR(rc);

        /* Because inode is NULL, ll_prep_md_op_data can not
         * be used here. So we allocate op_data ourselves
         */
        op_data = kzalloc(sizeof(*op_data), GFP_NOFS);
        if (!op_data)
                return ERR_PTR(-ENOMEM);

        op_data->op_fid1 = *fid;
        op_data->op_mode = eadatalen;
        op_data->op_valid = OBD_MD_FLEASIZE;

        /* mds_fid2dentry ignores f_type */
        rc = md_getattr(sbi->ll_md_exp, op_data, &req);
        kfree(op_data);
        if (rc) {
                CDEBUG(D_INFO, "can't get object attrs, fid " DFID ", rc %d\n",
                       PFID(fid), rc);
                return ERR_PTR(rc);
        }
        rc = ll_prep_inode(&inode, req, sb, NULL);
        ptlrpc_req_finished(req);
        if (rc)
                return ERR_PTR(rc);

        return inode;
}

struct lustre_nfs_fid {
        struct lu_fid   lnf_child;
        struct lu_fid   lnf_parent;
};

static struct dentry *
ll_iget_for_nfs(struct super_block *sb,
                struct lu_fid *fid, struct lu_fid *parent)
{
        struct inode  *inode;
        struct dentry *result;

        if (!fid_is_sane(fid))
                return ERR_PTR(-ESTALE);

        CDEBUG(D_INFO, "Get dentry for fid: " DFID "\n", PFID(fid));

        inode = search_inode_for_lustre(sb, fid);
        if (IS_ERR(inode))
                return ERR_CAST(inode);

        if (is_bad_inode(inode)) {
                /* we didn't find the right inode.. */
                iput(inode);
                return ERR_PTR(-ESTALE);
        }

        result = d_obtain_alias(inode);
        if (IS_ERR(result)) {
                iput(inode);
                return result;
        }

        /**
         * In case d_obtain_alias() found a disconnected dentry, always update
         * lli_pfid to allow later operation (normally open) have parent fid,
         * which may be used by MDS to create data.
         */
        if (parent) {
                struct ll_inode_info *lli = ll_i2info(inode);

                spin_lock(&lli->lli_lock);
                lli->lli_pfid = *parent;
                spin_unlock(&lli->lli_lock);
        }

        /* N.B. d_obtain_alias() drops inode ref on error */
        result = d_obtain_alias(inode);
        if (!IS_ERR(result)) {
                /*
                 * Need to signal to the ll_intent_file_open that
                 * we came from NFS and so opencache needs to be
                 * enabled for this one
                 */
                ll_d2d(result)->lld_nfs_dentry = 1;
        }

        return result;
}

/**
 * \a connectable - is nfsd will connect himself or this should be done
 *                at lustre
 *
 * The return value is file handle type:
 * 1 -- contains child file handle;
 * 2 -- contains child file handle and parent file handle;
 * 255 -- error.
 */
static int ll_encode_fh(struct inode *inode, __u32 *fh, int *plen,
                        struct inode *parent)
{
        int fileid_len = sizeof(struct lustre_nfs_fid) / 4;
        struct lustre_nfs_fid *nfs_fid = (void *)fh;

        CDEBUG(D_INFO, "%s: encoding for (" DFID ") maxlen=%d minlen=%d\n",
               ll_get_fsname(inode->i_sb, NULL, 0),
               PFID(ll_inode2fid(inode)), *plen, fileid_len);

        if (*plen < fileid_len) {
                *plen = fileid_len;
                return FILEID_INVALID;
        }

        nfs_fid->lnf_child = *ll_inode2fid(inode);
        if (parent)
                nfs_fid->lnf_parent = *ll_inode2fid(parent);
        else
                fid_zero(&nfs_fid->lnf_parent);
        *plen = fileid_len;

        return FILEID_LUSTRE;
}

static int ll_nfs_get_name_filldir(struct dir_context *ctx, const char *name,
                                   int namelen, loff_t hash, u64 ino,
                                   unsigned int type)
{
        /* It is hack to access lde_fid for comparison with lgd_fid.
         * So the input 'name' must be part of the 'lu_dirent'.
         */
        struct lu_dirent *lde = container_of0(name, struct lu_dirent, lde_name);
        struct ll_getname_data *lgd =
                container_of(ctx, struct ll_getname_data, ctx);
        struct lu_fid fid;

        fid_le_to_cpu(&fid, &lde->lde_fid);
        if (lu_fid_eq(&fid, &lgd->lgd_fid)) {
                memcpy(lgd->lgd_name, name, namelen);
                lgd->lgd_name[namelen] = 0;
                lgd->lgd_found = 1;
        }
        return lgd->lgd_found;
}

static int ll_get_name(struct dentry *dentry, char *name,
                       struct dentry *child)
{
        struct inode *dir = d_inode(dentry);
        int rc;
        struct ll_getname_data lgd = {
                .lgd_name = name,
                .lgd_fid = ll_i2info(d_inode(child))->lli_fid,
                .ctx.actor = ll_nfs_get_name_filldir,
        };
        struct md_op_data *op_data;
        __u64 pos = 0;

        if (!dir || !S_ISDIR(dir->i_mode)) {
                rc = -ENOTDIR;
                goto out;
        }

        if (!dir->i_fop) {
                rc = -EINVAL;
                goto out;
        }

        op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
                                     LUSTRE_OPC_ANY, dir);
        if (IS_ERR(op_data)) {
                rc = PTR_ERR(op_data);
                goto out;
        }

        op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
        inode_lock(dir);
        rc = ll_dir_read(dir, &pos, op_data, &lgd.ctx);
        inode_unlock(dir);
        ll_finish_md_op_data(op_data);
        if (!rc && !lgd.lgd_found)
                rc = -ENOENT;
out:
        return rc;
}

static struct dentry *ll_fh_to_dentry(struct super_block *sb, struct fid *fid,
                                      int fh_len, int fh_type)
{
        struct lustre_nfs_fid *nfs_fid = (struct lustre_nfs_fid *)fid;

        if (fh_type != FILEID_LUSTRE)
                return ERR_PTR(-EPROTO);

        return ll_iget_for_nfs(sb, &nfs_fid->lnf_child, &nfs_fid->lnf_parent);
}

static struct dentry *ll_fh_to_parent(struct super_block *sb, struct fid *fid,
                                      int fh_len, int fh_type)
{
        struct lustre_nfs_fid *nfs_fid = (struct lustre_nfs_fid *)fid;

        if (fh_type != FILEID_LUSTRE)
                return ERR_PTR(-EPROTO);

        return ll_iget_for_nfs(sb, &nfs_fid->lnf_parent, NULL);
}

int ll_dir_get_parent_fid(struct inode *dir, struct lu_fid *parent_fid)
{
        struct ptlrpc_request *req = NULL;
        struct ll_sb_info     *sbi;
        struct mdt_body       *body;
        static const char dotdot[] = "..";
        struct md_op_data     *op_data;
        int                rc;
        int                   lmmsize;

        LASSERT(dir && S_ISDIR(dir->i_mode));

        sbi = ll_s2sbi(dir->i_sb);

        CDEBUG(D_INFO, "%s: getting parent for (" DFID ")\n",
               ll_get_fsname(dir->i_sb, NULL, 0),
               PFID(ll_inode2fid(dir)));

        rc = ll_get_default_mdsize(sbi, &lmmsize);
        if (rc != 0)
                return rc;

        op_data = ll_prep_md_op_data(NULL, dir, NULL, dotdot,
                                     strlen(dotdot), lmmsize,
                                     LUSTRE_OPC_ANY, NULL);
        if (IS_ERR(op_data))
                return PTR_ERR(op_data);

        rc = md_getattr_name(sbi->ll_md_exp, op_data, &req);
        ll_finish_md_op_data(op_data);
        if (rc) {
                CERROR("%s: failure inode " DFID " get parent: rc = %d\n",
                       ll_get_fsname(dir->i_sb, NULL, 0),
                       PFID(ll_inode2fid(dir)), rc);
                return rc;
        }
        body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
        /*
         * LU-3952: MDT may lost the FID of its parent, we should not crash
         * the NFS server, ll_iget_for_nfs() will handle the error.
         */
        if (body->mbo_valid & OBD_MD_FLID) {
                CDEBUG(D_INFO, "parent for " DFID " is " DFID "\n",
                       PFID(ll_inode2fid(dir)), PFID(&body->mbo_fid1));
                *parent_fid = body->mbo_fid1;
        }

        ptlrpc_req_finished(req);
        return 0;
}

static struct dentry *ll_get_parent(struct dentry *dchild)
{
        struct lu_fid parent_fid = { 0 };
        struct dentry *dentry;
        int rc;

        rc = ll_dir_get_parent_fid(dchild->d_inode, &parent_fid);
        if (rc)
                return ERR_PTR(rc);

        dentry = ll_iget_for_nfs(dchild->d_inode->i_sb, &parent_fid, NULL);

        return dentry;
}

const struct export_operations lustre_export_operations = {
        .get_parent = ll_get_parent,
        .encode_fh  = ll_encode_fh,
        .get_name   = ll_get_name,
        .fh_to_dentry = ll_fh_to_dentry,
        .fh_to_parent = ll_fh_to_parent,
};