/*
 * 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.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * cl_device and cl_device_type implementation for VVP layer.
 *
 *   Author: Nikita Danilov <nikita.danilov@sun.com>
 */

#define DEBUG_SUBSYSTEM S_LLITE

#include "../include/obd.h"
#include "../include/lustre_lite.h"
#include "llite_internal.h"
#include "vvp_internal.h"

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

/*
 * vvp_ prefix stands for "Vfs Vm Posix". It corresponds to historical
 * "llite_" (var. "ll_") prefix.
 */

static struct kmem_cache *vvp_thread_kmem;
static struct kmem_cache *vvp_session_kmem;
static struct lu_kmem_descr vvp_caches[] = {
        {
                .ckd_cache = &vvp_thread_kmem,
                .ckd_name  = "vvp_thread_kmem",
                .ckd_size  = sizeof(struct vvp_thread_info),
        },
        {
                .ckd_cache = &vvp_session_kmem,
                .ckd_name  = "vvp_session_kmem",
                .ckd_size  = sizeof(struct vvp_session)
        },
        {
                .ckd_cache = NULL
        }
};

static void *vvp_key_init(const struct lu_context *ctx,
                          struct lu_context_key *key)
{
        struct vvp_thread_info *info;

        info = kmem_cache_zalloc(vvp_thread_kmem, GFP_NOFS);
        if (!info)
                info = ERR_PTR(-ENOMEM);
        return info;
}

static void vvp_key_fini(const struct lu_context *ctx,
                         struct lu_context_key *key, void *data)
{
        struct vvp_thread_info *info = data;

        kmem_cache_free(vvp_thread_kmem, info);
}

static void *vvp_session_key_init(const struct lu_context *ctx,
                                  struct lu_context_key *key)
{
        struct vvp_session *session;

        session = kmem_cache_zalloc(vvp_session_kmem, GFP_NOFS);
        if (!session)
                session = ERR_PTR(-ENOMEM);
        return session;
}

static void vvp_session_key_fini(const struct lu_context *ctx,
                                 struct lu_context_key *key, void *data)
{
        struct vvp_session *session = data;

        kmem_cache_free(vvp_session_kmem, session);
}

struct lu_context_key vvp_key = {
        .lct_tags = LCT_CL_THREAD,
        .lct_init = vvp_key_init,
        .lct_fini = vvp_key_fini
};

struct lu_context_key vvp_session_key = {
        .lct_tags = LCT_SESSION,
        .lct_init = vvp_session_key_init,
        .lct_fini = vvp_session_key_fini
};

/* type constructor/destructor: vvp_type_{init,fini,start,stop}(). */
LU_TYPE_INIT_FINI(vvp, &ccc_key, &ccc_session_key, &vvp_key, &vvp_session_key);

static const struct lu_device_operations vvp_lu_ops = {
        .ldo_object_alloc      = vvp_object_alloc
};

static const struct cl_device_operations vvp_cl_ops = {
        .cdo_req_init = ccc_req_init
};

static struct lu_device *vvp_device_alloc(const struct lu_env *env,
                                          struct lu_device_type *t,
                                          struct lustre_cfg *cfg)
{
        return ccc_device_alloc(env, t, cfg, &vvp_lu_ops, &vvp_cl_ops);
}

static const struct lu_device_type_operations vvp_device_type_ops = {
        .ldto_init = vvp_type_init,
        .ldto_fini = vvp_type_fini,

        .ldto_start = vvp_type_start,
        .ldto_stop  = vvp_type_stop,

        .ldto_device_alloc = vvp_device_alloc,
        .ldto_device_free  = ccc_device_free,
        .ldto_device_init  = ccc_device_init,
        .ldto_device_fini  = ccc_device_fini
};

struct lu_device_type vvp_device_type = {
        .ldt_tags     = LU_DEVICE_CL,
        .ldt_name     = LUSTRE_VVP_NAME,
        .ldt_ops      = &vvp_device_type_ops,
        .ldt_ctx_tags = LCT_CL_THREAD
};

/**
 * A mutex serializing calls to vvp_inode_fini() under extreme memory
 * pressure, when environments cannot be allocated.
 */
int vvp_global_init(void)
{
        int result;

        result = lu_kmem_init(vvp_caches);
        if (result == 0) {
                result = ccc_global_init(&vvp_device_type);
                if (result != 0)
                        lu_kmem_fini(vvp_caches);
        }
        return result;
}

void vvp_global_fini(void)
{
        ccc_global_fini(&vvp_device_type);
        lu_kmem_fini(vvp_caches);
}

/*****************************************************************************
 *
 * mirror obd-devices into cl devices.
 *
 */

int cl_sb_init(struct super_block *sb)
{
        struct ll_sb_info *sbi;
        struct cl_device  *cl;
        struct lu_env     *env;
        int rc = 0;
        int refcheck;

        sbi  = ll_s2sbi(sb);
        env = cl_env_get(&refcheck);
        if (!IS_ERR(env)) {
                cl = cl_type_setup(env, NULL, &vvp_device_type,
                                   sbi->ll_dt_exp->exp_obd->obd_lu_dev);
                if (!IS_ERR(cl)) {
                        cl2ccc_dev(cl)->cdv_sb = sb;
                        sbi->ll_cl = cl;
                        sbi->ll_site = cl2lu_dev(cl)->ld_site;
                }
                cl_env_put(env, &refcheck);
        } else
                rc = PTR_ERR(env);
        return rc;
}

int cl_sb_fini(struct super_block *sb)
{
        struct ll_sb_info *sbi;
        struct lu_env     *env;
        struct cl_device  *cld;
        int             refcheck;
        int             result;

        sbi = ll_s2sbi(sb);
        env = cl_env_get(&refcheck);
        if (!IS_ERR(env)) {
                cld = sbi->ll_cl;

                if (cld) {
                        cl_stack_fini(env, cld);
                        sbi->ll_cl = NULL;
                        sbi->ll_site = NULL;
                }
                cl_env_put(env, &refcheck);
                result = 0;
        } else {
                CERROR("Cannot cleanup cl-stack due to memory shortage.\n");
                result = PTR_ERR(env);
        }
        /*
         * If mount failed (sbi->ll_cl == NULL), and this there are no other
         * mounts, stop device types manually (this usually happens
         * automatically when last device is destroyed).
         */
        lu_types_stop();
        return result;
}

/****************************************************************************
 *
 * debugfs/lustre/llite/$MNT/dump_page_cache
 *
 ****************************************************************************/

/*
 * To represent contents of a page cache as a byte stream, following
 * information if encoded in 64bit offset:
 *
 *       - file hash bucket in lu_site::ls_hash[]       28bits
 *
 *       - how far file is from bucket head           4bits
 *
 *       - page index                              32bits
 *
 * First two data identify a file in the cache uniquely.
 */

#define PGC_OBJ_SHIFT (32 + 4)
#define PGC_DEPTH_SHIFT (32)

struct vvp_pgcache_id {
        unsigned                 vpi_bucket;
        unsigned                 vpi_depth;
        uint32_t                 vpi_index;

        unsigned                 vpi_curdep;
        struct lu_object_header *vpi_obj;
};

static void vvp_pgcache_id_unpack(loff_t pos, struct vvp_pgcache_id *id)
{
        CLASSERT(sizeof(pos) == sizeof(__u64));

        id->vpi_index  = pos & 0xffffffff;
        id->vpi_depth  = (pos >> PGC_DEPTH_SHIFT) & 0xf;
        id->vpi_bucket = (unsigned long long)pos >> PGC_OBJ_SHIFT;
}

static loff_t vvp_pgcache_id_pack(struct vvp_pgcache_id *id)
{
        return
                ((__u64)id->vpi_index) |
                ((__u64)id->vpi_depth  << PGC_DEPTH_SHIFT) |
                ((__u64)id->vpi_bucket << PGC_OBJ_SHIFT);
}

static int vvp_pgcache_obj_get(struct cfs_hash *hs, struct cfs_hash_bd *bd,
                               struct hlist_node *hnode, void *data)
{
        struct vvp_pgcache_id   *id  = data;
        struct lu_object_header *hdr = cfs_hash_object(hs, hnode);

        if (id->vpi_curdep-- > 0)
                return 0; /* continue */

        if (lu_object_is_dying(hdr))
                return 1;

        cfs_hash_get(hs, hnode);
        id->vpi_obj = hdr;
        return 1;
}

static struct cl_object *vvp_pgcache_obj(const struct lu_env *env,
                                         struct lu_device *dev,
                                         struct vvp_pgcache_id *id)
{
        LASSERT(lu_device_is_cl(dev));

        id->vpi_depth &= 0xf;
        id->vpi_obj    = NULL;
        id->vpi_curdep = id->vpi_depth;

        cfs_hash_hlist_for_each(dev->ld_site->ls_obj_hash, id->vpi_bucket,
                                vvp_pgcache_obj_get, id);
        if (id->vpi_obj) {
                struct lu_object *lu_obj;

                lu_obj = lu_object_locate(id->vpi_obj, dev->ld_type);
                if (lu_obj) {
                        lu_object_ref_add(lu_obj, "dump", current);
                        return lu2cl(lu_obj);
                }
                lu_object_put(env, lu_object_top(id->vpi_obj));

        } else if (id->vpi_curdep > 0) {
                id->vpi_depth = 0xf;
        }
        return NULL;
}

static loff_t vvp_pgcache_find(const struct lu_env *env,
                               struct lu_device *dev, loff_t pos)
{
        struct cl_object     *clob;
        struct lu_site       *site;
        struct vvp_pgcache_id id;

        site = dev->ld_site;
        vvp_pgcache_id_unpack(pos, &id);

        while (1) {
                if (id.vpi_bucket >= CFS_HASH_NHLIST(site->ls_obj_hash))
                        return ~0ULL;
                clob = vvp_pgcache_obj(env, dev, &id);
                if (clob) {
                        struct cl_object_header *hdr;
                        int                   nr;
                        struct cl_page    *pg;

                        /* got an object. Find next page. */
                        hdr = cl_object_header(clob);

                        spin_lock(&hdr->coh_page_guard);
                        nr = radix_tree_gang_lookup(&hdr->coh_tree,
                                                    (void **)&pg,
                                                    id.vpi_index, 1);
                        if (nr > 0) {
                                id.vpi_index = pg->cp_index;
                                /* Cant support over 16T file */
                                nr = !(pg->cp_index > 0xffffffff);
                        }
                        spin_unlock(&hdr->coh_page_guard);

                        lu_object_ref_del(&clob->co_lu, "dump", current);
                        cl_object_put(env, clob);
                        if (nr > 0)
                                return vvp_pgcache_id_pack(&id);
                }
                /* to the next object. */
                ++id.vpi_depth;
                id.vpi_depth &= 0xf;
                if (id.vpi_depth == 0 && ++id.vpi_bucket == 0)
                        return ~0ULL;
                id.vpi_index = 0;
        }
}

#define seq_page_flag(seq, page, flag, has_flags) do {            \
        if (test_bit(PG_##flag, &(page)->flags)) {                \
                seq_printf(seq, "%s"#flag, has_flags ? "|" : "");       \
                has_flags = 1;                                    \
        }                                                              \
} while (0)

static void vvp_pgcache_page_show(const struct lu_env *env,
                                  struct seq_file *seq, struct cl_page *page)
{
        struct ccc_page *cpg;
        struct page      *vmpage;
        int           has_flags;

        cpg = cl2ccc_page(cl_page_at(page, &vvp_device_type));
        vmpage = cpg->cpg_page;
        seq_printf(seq, " %5i | %p %p %s %s %s %s | %p %lu/%u(%p) %lu %u [",
                   0 /* gen */,
                   cpg, page,
                   "none",
                   cpg->cpg_write_queued ? "wq" : "- ",
                   cpg->cpg_defer_uptodate ? "du" : "- ",
                   PageWriteback(vmpage) ? "wb" : "-",
                   vmpage, vmpage->mapping->host->i_ino,
                   vmpage->mapping->host->i_generation,
                   vmpage->mapping->host, vmpage->index,
                   page_count(vmpage));
        has_flags = 0;
        seq_page_flag(seq, vmpage, locked, has_flags);
        seq_page_flag(seq, vmpage, error, has_flags);
        seq_page_flag(seq, vmpage, referenced, has_flags);
        seq_page_flag(seq, vmpage, uptodate, has_flags);
        seq_page_flag(seq, vmpage, dirty, has_flags);
        seq_page_flag(seq, vmpage, writeback, has_flags);
        seq_printf(seq, "%s]\n", has_flags ? "" : "-");
}

static int vvp_pgcache_show(struct seq_file *f, void *v)
{
        loff_t             pos;
        struct ll_sb_info       *sbi;
        struct cl_object        *clob;
        struct lu_env      *env;
        struct cl_page    *page;
        struct cl_object_header *hdr;
        struct vvp_pgcache_id    id;
        int                   refcheck;
        int                   result;

        env = cl_env_get(&refcheck);
        if (!IS_ERR(env)) {
                pos = *(loff_t *) v;
                vvp_pgcache_id_unpack(pos, &id);
                sbi = f->private;
                clob = vvp_pgcache_obj(env, &sbi->ll_cl->cd_lu_dev, &id);
                if (clob) {
                        hdr = cl_object_header(clob);

                        spin_lock(&hdr->coh_page_guard);
                        page = cl_page_lookup(hdr, id.vpi_index);
                        spin_unlock(&hdr->coh_page_guard);

                        seq_printf(f, "%8x@"DFID": ",
                                   id.vpi_index, PFID(&hdr->coh_lu.loh_fid));
                        if (page) {
                                vvp_pgcache_page_show(env, f, page);
                                cl_page_put(env, page);
                        } else
                                seq_puts(f, "missing\n");
                        lu_object_ref_del(&clob->co_lu, "dump", current);
                        cl_object_put(env, clob);
                } else
                        seq_printf(f, "%llx missing\n", pos);
                cl_env_put(env, &refcheck);
                result = 0;
        } else
                result = PTR_ERR(env);
        return result;
}

static void *vvp_pgcache_start(struct seq_file *f, loff_t *pos)
{
        struct ll_sb_info *sbi;
        struct lu_env     *env;
        int             refcheck;

        sbi = f->private;

        env = cl_env_get(&refcheck);
        if (!IS_ERR(env)) {
                sbi = f->private;
                if (sbi->ll_site->ls_obj_hash->hs_cur_bits > 64 - PGC_OBJ_SHIFT)
                        pos = ERR_PTR(-EFBIG);
                else {
                        *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev,
                                                *pos);
                        if (*pos == ~0ULL)
                                pos = NULL;
                }
                cl_env_put(env, &refcheck);
        }
        return pos;
}

static void *vvp_pgcache_next(struct seq_file *f, void *v, loff_t *pos)
{
        struct ll_sb_info *sbi;
        struct lu_env     *env;
        int             refcheck;

        env = cl_env_get(&refcheck);
        if (!IS_ERR(env)) {
                sbi = f->private;
                *pos = vvp_pgcache_find(env, &sbi->ll_cl->cd_lu_dev, *pos + 1);
                if (*pos == ~0ULL)
                        pos = NULL;
                cl_env_put(env, &refcheck);
        }
        return pos;
}

static void vvp_pgcache_stop(struct seq_file *f, void *v)
{
        /* Nothing to do */
}

static const struct seq_operations vvp_pgcache_ops = {
        .start = vvp_pgcache_start,
        .next  = vvp_pgcache_next,
        .stop  = vvp_pgcache_stop,
        .show  = vvp_pgcache_show
};

static int vvp_dump_pgcache_seq_open(struct inode *inode, struct file *filp)
{
        struct seq_file *seq;
        int rc;

        rc = seq_open(filp, &vvp_pgcache_ops);
        if (rc)
                return rc;

        seq = filp->private_data;
        seq->private = inode->i_private;

        return 0;
}

const struct file_operations vvp_dump_pgcache_file_ops = {
        .owner   = THIS_MODULE,
        .open    = vvp_dump_pgcache_seq_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release,
};