/*
 * 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;
	uint32_t		 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,
};