/*
 * 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) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * cl code shared between vvp and liblustre (and other Lustre clients in the
 * future).
 *
 *   Author: Nikita Danilov <nikita.danilov@sun.com>
 */

#define DEBUG_SUBSYSTEM S_LLITE

#include "../../include/linux/libcfs/libcfs.h"
# include <linux/fs.h>
# include <linux/sched.h>
# include <linux/mm.h>
# include <linux/quotaops.h>
# include <linux/highmem.h>
# include <linux/pagemap.h>
# include <linux/rbtree.h>

#include "../include/obd.h"
#include "../include/obd_support.h"
#include "../include/lustre_fid.h"
#include "../include/lustre_dlm.h"
#include "../include/lustre_ver.h"
#include "../include/lustre_mdc.h"
#include "../include/cl_object.h"

#include "../llite/llite_internal.h"

/*
 * ccc_ prefix stands for "Common Client Code".
 */

/*****************************************************************************
 *
 * Vvp device and device type functions.
 *
 */

/**
 * An `emergency' environment used by cl_inode_fini() when cl_env_get()
 * fails. Access to this environment is serialized by cl_inode_fini_guard
 * mutex.
 */
struct lu_env *cl_inode_fini_env;
u16 cl_inode_fini_refcheck;

/**
 * A mutex serializing calls to slp_inode_fini() under extreme memory
 * pressure, when environments cannot be allocated.
 */
static DEFINE_MUTEX(cl_inode_fini_guard);

int cl_setattr_ost(struct cl_object *obj, const struct iattr *attr,
                   unsigned int attr_flags)
{
        struct lu_env *env;
        struct cl_io  *io;
        int         result;
        u16 refcheck;

        env = cl_env_get(&refcheck);
        if (IS_ERR(env))
                return PTR_ERR(env);

        io = vvp_env_thread_io(env);
        io->ci_obj = obj;
        io->ci_verify_layout = 1;

        io->u.ci_setattr.sa_attr.lvb_atime = LTIME_S(attr->ia_atime);
        io->u.ci_setattr.sa_attr.lvb_mtime = LTIME_S(attr->ia_mtime);
        io->u.ci_setattr.sa_attr.lvb_ctime = LTIME_S(attr->ia_ctime);
        io->u.ci_setattr.sa_attr.lvb_size = attr->ia_size;
        io->u.ci_setattr.sa_attr_flags = attr_flags;
        io->u.ci_setattr.sa_valid = attr->ia_valid;
        io->u.ci_setattr.sa_parent_fid = lu_object_fid(&obj->co_lu);

again:
        if (cl_io_init(env, io, CIT_SETATTR, io->ci_obj) == 0) {
                struct vvp_io *vio = vvp_env_io(env);

                if (attr->ia_valid & ATTR_FILE)
                        /* populate the file descriptor for ftruncate to honor
                         * group lock - see LU-787
                         */
                        vio->vui_fd = LUSTRE_FPRIVATE(attr->ia_file);

                result = cl_io_loop(env, io);
        } else {
                result = io->ci_result;
        }
        cl_io_fini(env, io);
        if (unlikely(io->ci_need_restart))
                goto again;

        cl_env_put(env, &refcheck);
        return result;
}

/**
 * Initialize or update CLIO structures for regular files when new
 * meta-data arrives from the server.
 *
 * \param inode regular file inode
 * \param md    new file metadata from MDS
 * - allocates cl_object if necessary,
 * - updated layout, if object was already here.
 */
int cl_file_inode_init(struct inode *inode, struct lustre_md *md)
{
        struct lu_env   *env;
        struct ll_inode_info *lli;
        struct cl_object     *clob;
        struct lu_site       *site;
        struct lu_fid   *fid;
        struct cl_object_conf conf = {
                .coc_inode = inode,
                .u = {
                        .coc_layout = md->layout,
                }
        };
        int result = 0;
        u16 refcheck;

        LASSERT(md->body->mbo_valid & OBD_MD_FLID);
        LASSERT(S_ISREG(inode->i_mode));

        env = cl_env_get(&refcheck);
        if (IS_ERR(env))
                return PTR_ERR(env);

        site = ll_i2sbi(inode)->ll_site;
        lli  = ll_i2info(inode);
        fid  = &lli->lli_fid;
        LASSERT(fid_is_sane(fid));

        if (!lli->lli_clob) {
                /* clob is slave of inode, empty lli_clob means for new inode,
                 * there is no clob in cache with the given fid, so it is
                 * unnecessary to perform lookup-alloc-lookup-insert, just
                 * alloc and insert directly.
                 */
                LASSERT(inode->i_state & I_NEW);
                conf.coc_lu.loc_flags = LOC_F_NEW;
                clob = cl_object_find(env, lu2cl_dev(site->ls_top_dev),
                                      fid, &conf);
                if (!IS_ERR(clob)) {
                        /*
                         * No locking is necessary, as new inode is
                         * locked by I_NEW bit.
                         */
                        lli->lli_clob = clob;
                        lu_object_ref_add(&clob->co_lu, "inode", inode);
                } else {
                        result = PTR_ERR(clob);
                }
        } else {
                result = cl_conf_set(env, lli->lli_clob, &conf);
        }

        cl_env_put(env, &refcheck);

        if (result != 0)
                CERROR("Failure to initialize cl object " DFID ": %d\n",
                       PFID(fid), result);
        return result;
}

/**
 * Wait for others drop their references of the object at first, then we drop
 * the last one, which will lead to the object be destroyed immediately.
 * Must be called after cl_object_kill() against this object.
 *
 * The reason we want to do this is: destroying top object will wait for sub
 * objects being destroyed first, so we can't let bottom layer (e.g. from ASTs)
 * to initiate top object destroying which may deadlock. See bz22520.
 */
static void cl_object_put_last(struct lu_env *env, struct cl_object *obj)
{
        struct lu_object_header *header = obj->co_lu.lo_header;
        wait_queue_entry_t         waiter;

        if (unlikely(atomic_read(&header->loh_ref) != 1)) {
                struct lu_site *site = obj->co_lu.lo_dev->ld_site;
                struct lu_site_bkt_data *bkt;

                bkt = lu_site_bkt_from_fid(site, &header->loh_fid);

                init_waitqueue_entry(&waiter, current);
                add_wait_queue(&bkt->lsb_marche_funebre, &waiter);

                while (1) {
                        set_current_state(TASK_UNINTERRUPTIBLE);
                        if (atomic_read(&header->loh_ref) == 1)
                                break;
                        schedule();
                }

                set_current_state(TASK_RUNNING);
                remove_wait_queue(&bkt->lsb_marche_funebre, &waiter);
        }

        cl_object_put(env, obj);
}

void cl_inode_fini(struct inode *inode)
{
        struct lu_env      *env;
        struct ll_inode_info    *lli  = ll_i2info(inode);
        struct cl_object        *clob = lli->lli_clob;
        u16 refcheck;
        int emergency;

        if (clob) {
                env = cl_env_get(&refcheck);
                emergency = IS_ERR(env);
                if (emergency) {
                        mutex_lock(&cl_inode_fini_guard);
                        LASSERT(cl_inode_fini_env);
                        env = cl_inode_fini_env;
                }
                /*
                 * cl_object cache is a slave to inode cache (which, in turn
                 * is a slave to dentry cache), don't keep cl_object in memory
                 * when its master is evicted.
                 */
                cl_object_kill(env, clob);
                lu_object_ref_del(&clob->co_lu, "inode", inode);
                cl_object_put_last(env, clob);
                lli->lli_clob = NULL;
                if (emergency)
                        mutex_unlock(&cl_inode_fini_guard);
                else
                        cl_env_put(env, &refcheck);
        }
}

/**
 * build inode number from passed @fid
 */
__u64 cl_fid_build_ino(const struct lu_fid *fid, int api32)
{
        if (BITS_PER_LONG == 32 || api32)
                return fid_flatten32(fid);
        else
                return fid_flatten(fid);
}

/**
 * build inode generation from passed @fid.  If our FID overflows the 32-bit
 * inode number then return a non-zero generation to distinguish them.
 */
__u32 cl_fid_build_gen(const struct lu_fid *fid)
{
        __u32 gen;

        if (fid_is_igif(fid)) {
                gen = lu_igif_gen(fid);
                return gen;
        }

        gen = fid_flatten(fid) >> 32;
        return gen;
}