/*
 * 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) 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/lvfs/lvfs_linux.c
 *
 * Author: Andreas Dilger <adilger@clusterfs.com>
 */

#define DEBUG_SUBSYSTEM S_FILTER

#include <linux/fs.h>
#include <asm/unistd.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/libcfs/libcfs.h>
#include <linux/module.h>
#include <linux/lustre_compat25.h>
#include <lvfs.h>

#include <obd.h>
#include <lustre_lib.h>

struct lprocfs_stats *obd_memory = NULL;
EXPORT_SYMBOL(obd_memory);
/* refine later and change to seqlock or simlar from libcfs */

/* Debugging check only needed during development */
#ifdef OBD_CTXT_DEBUG
# define ASSERT_CTXT_MAGIC(magic) LASSERT((magic) == OBD_RUN_CTXT_MAGIC)
# define ASSERT_NOT_KERNEL_CTXT(msg) LASSERTF(!segment_eq(get_fs(), get_ds()),\
					      msg)
# define ASSERT_KERNEL_CTXT(msg) LASSERTF(segment_eq(get_fs(), get_ds()), msg)
#else
# define ASSERT_CTXT_MAGIC(magic) do {} while (0)
# define ASSERT_NOT_KERNEL_CTXT(msg) do {} while (0)
# define ASSERT_KERNEL_CTXT(msg) do {} while (0)
#endif

static void push_group_info(struct lvfs_run_ctxt *save,
			    struct group_info *ginfo)
{
	if (!ginfo) {
		save->ngroups = current_ngroups;
		current_ngroups = 0;
	} else {
		struct cred *cred;
		task_lock(current);
		save->group_info = current_cred()->group_info;
		cred = prepare_creds();
		if (cred) {
			cred->group_info = ginfo;
			commit_creds(cred);
		}
		task_unlock(current);
	}
}

static void pop_group_info(struct lvfs_run_ctxt *save,
			   struct group_info *ginfo)
{
	if (!ginfo) {
		current_ngroups = save->ngroups;
	} else {
		struct cred *cred;
		task_lock(current);
		cred = prepare_creds();
		if (cred) {
			cred->group_info = save->group_info;
			commit_creds(cred);
		}
		task_unlock(current);
	}
}

/* push / pop to root of obd store */
void push_ctxt(struct lvfs_run_ctxt *save, struct lvfs_run_ctxt *new_ctx,
	       struct lvfs_ucred *uc)
{
	/* if there is underlaying dt_device then push_ctxt is not needed */
	if (new_ctx->dt != NULL)
		return;

	/* ASSERT_NOT_KERNEL_CTXT("already in kernel context!\n"); */
	ASSERT_CTXT_MAGIC(new_ctx->magic);
	OBD_SET_CTXT_MAGIC(save);

	save->fs = get_fs();
	LASSERT(d_count(cfs_fs_pwd(current->fs)));
	LASSERT(d_count(new_ctx->pwd));
	save->pwd = dget(cfs_fs_pwd(current->fs));
	save->pwdmnt = mntget(cfs_fs_mnt(current->fs));
	save->luc.luc_umask = current_umask();
	save->ngroups = current_cred()->group_info->ngroups;

	LASSERT(save->pwd);
	LASSERT(save->pwdmnt);
	LASSERT(new_ctx->pwd);
	LASSERT(new_ctx->pwdmnt);

	if (uc) {
		struct cred *cred;
		save->luc.luc_uid = current_uid();
		save->luc.luc_gid = current_gid();
		save->luc.luc_fsuid = current_fsuid();
		save->luc.luc_fsgid = current_fsgid();
		save->luc.luc_cap = current_cap();

		cred = prepare_creds();
		if (cred) {
			cred->uid = uc->luc_uid;
			cred->gid = uc->luc_gid;
			cred->fsuid = uc->luc_fsuid;
			cred->fsgid = uc->luc_fsgid;
			cred->cap_effective = uc->luc_cap;
			commit_creds(cred);
		}

		push_group_info(save,
				uc->luc_ginfo ?:
				uc->luc_identity ? uc->luc_identity->mi_ginfo :
						   NULL);
	}
	current->fs->umask = 0; /* umask already applied on client */
	set_fs(new_ctx->fs);
	ll_set_fs_pwd(current->fs, new_ctx->pwdmnt, new_ctx->pwd);
}
EXPORT_SYMBOL(push_ctxt);

void pop_ctxt(struct lvfs_run_ctxt *saved, struct lvfs_run_ctxt *new_ctx,
	      struct lvfs_ucred *uc)
{
	/* if there is underlaying dt_device then pop_ctxt is not needed */
	if (new_ctx->dt != NULL)
		return;

	ASSERT_CTXT_MAGIC(saved->magic);
	ASSERT_KERNEL_CTXT("popping non-kernel context!\n");

	LASSERTF(cfs_fs_pwd(current->fs) == new_ctx->pwd, "%p != %p\n",
		 cfs_fs_pwd(current->fs), new_ctx->pwd);
	LASSERTF(cfs_fs_mnt(current->fs) == new_ctx->pwdmnt, "%p != %p\n",
		 cfs_fs_mnt(current->fs), new_ctx->pwdmnt);

	set_fs(saved->fs);
	ll_set_fs_pwd(current->fs, saved->pwdmnt, saved->pwd);

	dput(saved->pwd);
	mntput(saved->pwdmnt);
	current->fs->umask = saved->luc.luc_umask;
	if (uc) {
		struct cred *cred;
		cred = prepare_creds();
		if (cred) {
			cred->uid = saved->luc.luc_uid;
			cred->gid = saved->luc.luc_gid;
			cred->fsuid = saved->luc.luc_fsuid;
			cred->fsgid = saved->luc.luc_fsgid;
			cred->cap_effective = saved->luc.luc_cap;
			commit_creds(cred);
		}

		pop_group_info(saved,
			       uc->luc_ginfo ?:
			       uc->luc_identity ? uc->luc_identity->mi_ginfo :
						  NULL);
	}
}
EXPORT_SYMBOL(pop_ctxt);

/* utility to rename a file */
int lustre_rename(struct dentry *dir, struct vfsmount *mnt,
		  char *oldname, char *newname)
{
	struct dentry *dchild_old, *dchild_new;
	int err = 0;

	ASSERT_KERNEL_CTXT("kernel doing rename outside kernel context\n");
	CDEBUG(D_INODE, "renaming file %.*s to %.*s\n",
	       (int)strlen(oldname), oldname, (int)strlen(newname), newname);

	dchild_old = ll_lookup_one_len(oldname, dir, strlen(oldname));
	if (IS_ERR(dchild_old))
		return PTR_ERR(dchild_old);

	if (!dchild_old->d_inode)
		GOTO(put_old, err = -ENOENT);

	dchild_new = ll_lookup_one_len(newname, dir, strlen(newname));
	if (IS_ERR(dchild_new))
		GOTO(put_old, err = PTR_ERR(dchild_new));

	err = ll_vfs_rename(dir->d_inode, dchild_old, mnt,
			    dir->d_inode, dchild_new, mnt, NULL);

	dput(dchild_new);
put_old:
	dput(dchild_old);
	return err;
}
EXPORT_SYMBOL(lustre_rename);

/* Note: dput(dchild) will *not* be called if there is an error */
struct l_file *l_dentry_open(struct lvfs_run_ctxt *ctxt, struct l_dentry *de,
			     int flags)
{
	struct path path = {
		.dentry = de,
		.mnt = ctxt->pwdmnt,
	};
	return dentry_open(&path, flags, current_cred());
}
EXPORT_SYMBOL(l_dentry_open);

#ifdef LPROCFS
__s64 lprocfs_read_helper(struct lprocfs_counter *lc,
			  struct lprocfs_counter_header *header,
			  enum lprocfs_stats_flags flags,
			  enum lprocfs_fields_flags field)
{
	__s64 ret = 0;

	if (lc == NULL || header == NULL)
		return 0;

	switch (field) {
	case LPROCFS_FIELDS_FLAGS_CONFIG:
		ret = header->lc_config;
		break;
	case LPROCFS_FIELDS_FLAGS_SUM:
		ret = lc->lc_sum;
		if ((flags & LPROCFS_STATS_FLAG_IRQ_SAFE) != 0)
			ret += lc->lc_sum_irq;
		break;
	case LPROCFS_FIELDS_FLAGS_MIN:
		ret = lc->lc_min;
		break;
	case LPROCFS_FIELDS_FLAGS_MAX:
		ret = lc->lc_max;
		break;
	case LPROCFS_FIELDS_FLAGS_AVG:
		ret = (lc->lc_max - lc->lc_min) / 2;
		break;
	case LPROCFS_FIELDS_FLAGS_SUMSQUARE:
		ret = lc->lc_sumsquare;
		break;
	case LPROCFS_FIELDS_FLAGS_COUNT:
		ret = lc->lc_count;
		break;
	default:
		break;
	}

	return ret;
}
EXPORT_SYMBOL(lprocfs_read_helper);
#endif /* LPROCFS */

MODULE_AUTHOR("Sun Microsystems, Inc. <http://www.lustre.org/>");
MODULE_DESCRIPTION("Lustre VFS Filesystem Helper v0.1");
MODULE_LICENSE("GPL");