// 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) 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>
 *   Author: Jinshan Xiong <jinshan.xiong@intel.com>
 */

#define DEBUG_SUBSYSTEM S_LLITE

#include <obd.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 *ll_thread_kmem;
struct kmem_cache *vvp_lock_kmem;
struct kmem_cache *vvp_object_kmem;
static struct kmem_cache *vvp_session_kmem;
static struct kmem_cache *vvp_thread_kmem;

static struct lu_kmem_descr vvp_caches[] = {
        {
                .ckd_cache = &ll_thread_kmem,
                .ckd_name  = "ll_thread_kmem",
                .ckd_size  = sizeof(struct ll_thread_info),
        },
        {
                .ckd_cache = &vvp_lock_kmem,
                .ckd_name  = "vvp_lock_kmem",
                .ckd_size  = sizeof(struct vvp_lock),
        },
        {
                .ckd_cache = &vvp_object_kmem,
                .ckd_name  = "vvp_object_kmem",
                .ckd_size  = sizeof(struct vvp_object),
        },
        {
                .ckd_cache = &vvp_session_kmem,
                .ckd_name  = "vvp_session_kmem",
                .ckd_size  = sizeof(struct vvp_session)
        },
        {
                .ckd_cache = &vvp_thread_kmem,
                .ckd_name  = "vvp_thread_kmem",
                .ckd_size  = sizeof(struct vvp_thread_info),
        },
        {
                .ckd_cache = NULL
        }
};

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

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

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

        kmem_cache_free(ll_thread_kmem, info);
}

struct lu_context_key ll_thread_key = {
        .lct_tags = LCT_CL_THREAD,
        .lct_init = ll_thread_key_init,
        .lct_fini = ll_thread_key_fini
};

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_session_key = {
        .lct_tags = LCT_SESSION,
        .lct_init = vvp_session_key_init,
        .lct_fini = vvp_session_key_fini
};

static void *vvp_thread_key_init(const struct lu_context *ctx,
                                 struct lu_context_key *key)
{
        struct vvp_thread_info *vti;

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

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

        kmem_cache_free(vvp_thread_kmem, vti);
}

struct lu_context_key vvp_thread_key = {
        .lct_tags = LCT_CL_THREAD,
        .lct_init = vvp_thread_key_init,
        .lct_fini = vvp_thread_key_fini
};

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

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

static struct lu_device *vvp_device_free(const struct lu_env *env,
                                         struct lu_device *d)
{
        struct vvp_device *vdv  = lu2vvp_dev(d);
        struct cl_site    *site = lu2cl_site(d->ld_site);
        struct lu_device  *next = cl2lu_dev(vdv->vdv_next);

        if (d->ld_site) {
                cl_site_fini(site);
                kfree(site);
        }
        cl_device_fini(lu2cl_dev(d));
        kfree(vdv);
        return next;
}

static struct lu_device *vvp_device_alloc(const struct lu_env *env,
                                          struct lu_device_type *t,
                                          struct lustre_cfg *cfg)
{
        struct vvp_device *vdv;
        struct lu_device  *lud;
        struct cl_site    *site;
        int rc;

        vdv = kzalloc(sizeof(*vdv), GFP_NOFS);
        if (!vdv)
                return ERR_PTR(-ENOMEM);

        lud = &vdv->vdv_cl.cd_lu_dev;
        cl_device_init(&vdv->vdv_cl, t);
        vvp2lu_dev(vdv)->ld_ops = &vvp_lu_ops;

        site = kzalloc(sizeof(*site), GFP_NOFS);
        if (site) {
                rc = cl_site_init(site, &vdv->vdv_cl);
                if (rc == 0) {
                        rc = lu_site_init_finish(&site->cs_lu);
                } else {
                        LASSERT(!lud->ld_site);
                        CERROR("Cannot init lu_site, rc %d.\n", rc);
                        kfree(site);
                }
        } else {
                rc = -ENOMEM;
        }
        if (rc != 0) {
                vvp_device_free(env, lud);
                lud = ERR_PTR(rc);
        }
        return lud;
}

static int vvp_device_init(const struct lu_env *env, struct lu_device *d,
                           const char *name, struct lu_device *next)
{
        struct vvp_device  *vdv;
        int rc;

        vdv = lu2vvp_dev(d);
        vdv->vdv_next = lu2cl_dev(next);

        LASSERT(d->ld_site && next->ld_type);
        next->ld_site = d->ld_site;
        rc = next->ld_type->ldt_ops->ldto_device_init(env, next,
                                                      next->ld_type->ldt_name,
                                                      NULL);
        if (rc == 0) {
                lu_device_get(next);
                lu_ref_add(&next->ld_reference, "lu-stack", &lu_site_init);
        }
        return rc;
}

static struct lu_device *vvp_device_fini(const struct lu_env *env,
                                         struct lu_device *d)
{
        return cl2lu_dev(lu2vvp_dev(d)->vdv_next);
}

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       = vvp_device_free,
        .ldto_device_init       = vvp_device_init,
        .ldto_device_fini       = vvp_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 rc;

        rc = lu_kmem_init(vvp_caches);
        if (rc != 0)
                return rc;

        rc = lu_device_type_init(&vvp_device_type);
        if (rc != 0)
                goto out_kmem;

        return 0;

out_kmem:
        lu_kmem_fini(vvp_caches);

        return rc;
}

void vvp_global_fini(void)
{
        lu_device_type_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;
        u16 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)) {
                        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;
        u16 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);
        }
        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 int             vpi_bucket;
        unsigned int             vpi_depth;
        u32                      vpi_index;

        unsigned int             vpi_curdep;
        struct lu_object_header *vpi_obj;
};

static void vvp_pgcache_id_unpack(loff_t pos, struct vvp_pgcache_id *id)
{
        BUILD_BUG_ON(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 inode *inode = vvp_object_inode(clob);
                        struct page *vmpage;
                        int nr;

                        nr = find_get_pages_contig(inode->i_mapping,
                                                   id.vpi_index, 1, &vmpage);
                        if (nr > 0) {
                                id.vpi_index = vmpage->index;
                                /* Cant support over 16T file */
                                nr = !(vmpage->index > 0xffffffff);
                                put_page(vmpage);
                        }

                        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 vvp_page *vpg;
        struct page      *vmpage;
        int           has_flags;

        vpg = cl2vvp_page(cl_page_at(page, &vvp_device_type));
        vmpage = vpg->vpg_page;
        seq_printf(seq, " %5i | %p %p %s %s %s | %p " DFID "(%p) %lu %u [",
                   0 /* gen */,
                   vpg, page,
                   "none",
                   vpg->vpg_defer_uptodate ? "du" : "- ",
                   PageWriteback(vmpage) ? "wb" : "-",
                   vmpage, PFID(ll_inode2fid(vmpage->mapping->host)),
                   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 vvp_pgcache_id    id;
        u16 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) {
                        struct inode *inode = vvp_object_inode(clob);
                        struct cl_page *page = NULL;
                        struct page *vmpage;

                        result = find_get_pages_contig(inode->i_mapping,
                                                       id.vpi_index, 1,
                                                       &vmpage);
                        if (result > 0) {
                                lock_page(vmpage);
                                page = cl_vmpage_page(vmpage, clob);
                                unlock_page(vmpage);
                                put_page(vmpage);
                        }

                        seq_printf(f, "%8x@" DFID ": ", id.vpi_index,
                                   PFID(lu_object_fid(&clob->co_lu)));
                        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;
        u16 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;
        u16 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,
};