/*
 * SPU file system
 *
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * Author: Arnd Bergmann <arndb@de.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/file.h>
#include <linux/fs.h>
#include <linux/backing-dev.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/parser.h>

#include <asm/io.h>
#include <asm/semaphore.h>
#include <asm/spu.h>
#include <asm/uaccess.h>

#include "spufs.h"

static kmem_cache_t *spufs_inode_cache;

static struct inode *
spufs_alloc_inode(struct super_block *sb)
{
	struct spufs_inode_info *ei;

	ei = kmem_cache_alloc(spufs_inode_cache, SLAB_KERNEL);
	if (!ei)
		return NULL;
	return &ei->vfs_inode;
}

static void
spufs_destroy_inode(struct inode *inode)
{
	kmem_cache_free(spufs_inode_cache, SPUFS_I(inode));
}

static void
spufs_init_once(void *p, kmem_cache_t * cachep, unsigned long flags)
{
	struct spufs_inode_info *ei = p;

	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
	    SLAB_CTOR_CONSTRUCTOR) {
		inode_init_once(&ei->vfs_inode);
	}
}

static struct inode *
spufs_new_inode(struct super_block *sb, int mode)
{
	struct inode *inode;

	inode = new_inode(sb);
	if (!inode)
		goto out;

	inode->i_mode = mode;
	inode->i_uid = current->fsuid;
	inode->i_gid = current->fsgid;
	inode->i_blksize = PAGE_CACHE_SIZE;
	inode->i_blocks = 0;
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
out:
	return inode;
}

static int
spufs_setattr(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;

	if ((attr->ia_valid & ATTR_SIZE) &&
	    (attr->ia_size != inode->i_size))
		return -EINVAL;
	return inode_setattr(inode, attr);
}


static int
spufs_new_file(struct super_block *sb, struct dentry *dentry,
		const struct file_operations *fops, int mode,
		struct spu_context *ctx)
{
	static struct inode_operations spufs_file_iops = {
		.setattr = spufs_setattr,
	};
	struct inode *inode;
	int ret;

	ret = -ENOSPC;
	inode = spufs_new_inode(sb, S_IFREG | mode);
	if (!inode)
		goto out;

	ret = 0;
	inode->i_op = &spufs_file_iops;
	inode->i_fop = fops;
	inode->u.generic_ip = SPUFS_I(inode)->i_ctx = get_spu_context(ctx);
	d_add(dentry, inode);
out:
	return ret;
}

static void
spufs_delete_inode(struct inode *inode)
{
	if (SPUFS_I(inode)->i_ctx)
		put_spu_context(SPUFS_I(inode)->i_ctx);
	clear_inode(inode);
}

static void spufs_prune_dir(struct dentry *dir)
{
	struct dentry *dentry, *tmp;
	mutex_lock(&dir->d_inode->i_mutex);
	list_for_each_entry_safe(dentry, tmp, &dir->d_subdirs, d_u.d_child) {
		spin_lock(&dcache_lock);
		spin_lock(&dentry->d_lock);
		if (!(d_unhashed(dentry)) && dentry->d_inode) {
			dget_locked(dentry);
			__d_drop(dentry);
			spin_unlock(&dentry->d_lock);
			simple_unlink(dir->d_inode, dentry);
			spin_unlock(&dcache_lock);
			dput(dentry);
		} else {
			spin_unlock(&dentry->d_lock);
			spin_unlock(&dcache_lock);
		}
	}
	shrink_dcache_parent(dir);
	mutex_unlock(&dir->d_inode->i_mutex);
}

static int spufs_rmdir(struct inode *root, struct dentry *dir_dentry)
{
	struct spu_context *ctx;

	/* remove all entries */
	mutex_lock(&root->i_mutex);
	spufs_prune_dir(dir_dentry);
	mutex_unlock(&root->i_mutex);

	/* We have to give up the mm_struct */
	ctx = SPUFS_I(dir_dentry->d_inode)->i_ctx;
	spu_forget(ctx);

	/* XXX Do we need to hold i_mutex here ? */
	return simple_rmdir(root, dir_dentry);
}

static int spufs_fill_dir(struct dentry *dir, struct tree_descr *files,
			  int mode, struct spu_context *ctx)
{
	struct dentry *dentry;
	int ret;

	while (files->name && files->name[0]) {
		ret = -ENOMEM;
		dentry = d_alloc_name(dir, files->name);
		if (!dentry)
			goto out;
		ret = spufs_new_file(dir->d_sb, dentry, files->ops,
					files->mode & mode, ctx);
		if (ret)
			goto out;
		files++;
	}
	return 0;
out:
	spufs_prune_dir(dir);
	return ret;
}

static int spufs_dir_close(struct inode *inode, struct file *file)
{
	struct inode *dir;
	struct dentry *dentry;
	int ret;

	dentry = file->f_dentry;
	dir = dentry->d_parent->d_inode;

	ret = spufs_rmdir(dir, dentry);
	WARN_ON(ret);

	return dcache_dir_close(inode, file);
}

struct inode_operations spufs_dir_inode_operations = {
	.lookup = simple_lookup,
};

struct file_operations spufs_context_fops = {
	.open		= dcache_dir_open,
	.release	= spufs_dir_close,
	.llseek		= dcache_dir_lseek,
	.read		= generic_read_dir,
	.readdir	= dcache_readdir,
	.fsync		= simple_sync_file,
};

static int
spufs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	int ret;
	struct inode *inode;
	struct spu_context *ctx;

	ret = -ENOSPC;
	inode = spufs_new_inode(dir->i_sb, mode | S_IFDIR);
	if (!inode)
		goto out;

	if (dir->i_mode & S_ISGID) {
		inode->i_gid = dir->i_gid;
		inode->i_mode &= S_ISGID;
	}
	ctx = alloc_spu_context(inode->i_mapping);
	SPUFS_I(inode)->i_ctx = ctx;
	if (!ctx)
		goto out_iput;

	inode->i_op = &spufs_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	ret = spufs_fill_dir(dentry, spufs_dir_contents, mode, ctx);
	if (ret)
		goto out_free_ctx;

	d_instantiate(dentry, inode);
	dget(dentry);
	dir->i_nlink++;
	dentry->d_inode->i_nlink++;
	goto out;

out_free_ctx:
	put_spu_context(ctx);
out_iput:
	iput(inode);
out:
	return ret;
}

static int spufs_context_open(struct dentry *dentry, struct vfsmount *mnt)
{
	int ret;
	struct file *filp;

	ret = get_unused_fd();
	if (ret < 0) {
		dput(dentry);
		mntput(mnt);
		goto out;
	}

	filp = dentry_open(dentry, mnt, O_RDONLY);
	if (IS_ERR(filp)) {
		put_unused_fd(ret);
		ret = PTR_ERR(filp);
		goto out;
	}

	filp->f_op = &spufs_context_fops;
	fd_install(ret, filp);
out:
	return ret;
}

static struct file_system_type spufs_type;

long spufs_create_thread(struct nameidata *nd,
			 unsigned int flags, mode_t mode)
{
	struct dentry *dentry;
	int ret;

	/* need to be at the root of spufs */
	ret = -EINVAL;
	if (nd->dentry->d_sb->s_type != &spufs_type ||
	    nd->dentry != nd->dentry->d_sb->s_root)
		goto out;

	dentry = lookup_create(nd, 1);
	ret = PTR_ERR(dentry);
	if (IS_ERR(dentry))
		goto out_dir;

	ret = -EEXIST;
	if (dentry->d_inode)
		goto out_dput;

	mode &= ~current->fs->umask;
	ret = spufs_mkdir(nd->dentry->d_inode, dentry, mode & S_IRWXUGO);
	if (ret)
		goto out_dput;

	/*
	 * get references for dget and mntget, will be released
	 * in error path of *_open().
	 */
	ret = spufs_context_open(dget(dentry), mntget(nd->mnt));
	if (ret < 0)
		spufs_rmdir(nd->dentry->d_inode, dentry);

out_dput:
	dput(dentry);
out_dir:
	mutex_unlock(&nd->dentry->d_inode->i_mutex);
out:
	return ret;
}

/* File system initialization */
enum {
	Opt_uid, Opt_gid, Opt_err,
};

static match_table_t spufs_tokens = {
	{ Opt_uid, "uid=%d" },
	{ Opt_gid, "gid=%d" },
	{ Opt_err, NULL  },
};

static int
spufs_parse_options(char *options, struct inode *root)
{
	char *p;
	substring_t args[MAX_OPT_ARGS];

	while ((p = strsep(&options, ",")) != NULL) {
		int token, option;

		if (!*p)
			continue;

		token = match_token(p, spufs_tokens, args);
		switch (token) {
		case Opt_uid:
			if (match_int(&args[0], &option))
				return 0;
			root->i_uid = option;
			break;
		case Opt_gid:
			if (match_int(&args[0], &option))
				return 0;
			root->i_gid = option;
			break;
		default:
			return 0;
		}
	}
	return 1;
}

static int
spufs_create_root(struct super_block *sb, void *data)
{
	struct inode *inode;
	int ret;

	ret = -ENOMEM;
	inode = spufs_new_inode(sb, S_IFDIR | 0775);
	if (!inode)
		goto out;

	inode->i_op = &spufs_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	SPUFS_I(inode)->i_ctx = NULL;

	ret = -EINVAL;
	if (!spufs_parse_options(data, inode))
		goto out_iput;

	ret = -ENOMEM;
	sb->s_root = d_alloc_root(inode);
	if (!sb->s_root)
		goto out_iput;

	return 0;
out_iput:
	iput(inode);
out:
	return ret;
}

static int
spufs_fill_super(struct super_block *sb, void *data, int silent)
{
	static struct super_operations s_ops = {
		.alloc_inode = spufs_alloc_inode,
		.destroy_inode = spufs_destroy_inode,
		.statfs = simple_statfs,
		.delete_inode = spufs_delete_inode,
		.drop_inode = generic_delete_inode,
	};

	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = SPUFS_MAGIC;
	sb->s_op = &s_ops;

	return spufs_create_root(sb, data);
}

static struct super_block *
spufs_get_sb(struct file_system_type *fstype, int flags,
		const char *name, void *data)
{
	return get_sb_single(fstype, flags, data, spufs_fill_super);
}

static struct file_system_type spufs_type = {
	.owner = THIS_MODULE,
	.name = "spufs",
	.get_sb = spufs_get_sb,
	.kill_sb = kill_litter_super,
};

static int spufs_init(void)
{
	int ret;
	ret = -ENOMEM;
	spufs_inode_cache = kmem_cache_create("spufs_inode_cache",
			sizeof(struct spufs_inode_info), 0,
			SLAB_HWCACHE_ALIGN, spufs_init_once, NULL);

	if (!spufs_inode_cache)
		goto out;
	if (spu_sched_init() != 0) {
		kmem_cache_destroy(spufs_inode_cache);
		goto out;
	}
	ret = register_filesystem(&spufs_type);
	if (ret)
		goto out_cache;
	ret = register_spu_syscalls(&spufs_calls);
	if (ret)
		goto out_fs;
	return 0;
out_fs:
	unregister_filesystem(&spufs_type);
out_cache:
	kmem_cache_destroy(spufs_inode_cache);
out:
	return ret;
}
module_init(spufs_init);

static void spufs_exit(void)
{
	spu_sched_exit();
	unregister_spu_syscalls(&spufs_calls);
	unregister_filesystem(&spufs_type);
	kmem_cache_destroy(spufs_inode_cache);
}
module_exit(spufs_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");