text: /* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * dlmfs.c
   *
   * Code which implements the kernel side of a minimal userspace
   * interface to our DLM. This file handles the virtual file system
   * used for communication with userspace. Credit should go to ramfs,
   * which was a template for the fs side of this module.
   *
   * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
   *
   * 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 of the License, 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., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  
  /* Simple VFS hooks based on: */
  /*
   * Resizable simple ram filesystem for Linux.
   *
   * Copyright (C) 2000 Linus Torvalds.
   *               2000 Transmeta Corp.
   */
  
  #include <linux/module.h>
  #include <linux/fs.h>
  #include <linux/pagemap.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>
  #include <linux/init.h>
  #include <linux/string.h>
  #include <linux/backing-dev.h>
  #include <linux/poll.h>
  
  #include <asm/uaccess.h>
  
  #include "stackglue.h"
  #include "userdlm.h"
  
  #define MLOG_MASK_PREFIX ML_DLMFS
  #include "cluster/masklog.h"
  
  
  static const struct super_operations dlmfs_ops;
  static const struct file_operations dlmfs_file_operations;
  static const struct inode_operations dlmfs_dir_inode_operations;
  static const struct inode_operations dlmfs_root_inode_operations;
  static const struct inode_operations dlmfs_file_inode_operations;
  static struct kmem_cache *dlmfs_inode_cache;
  
  struct workqueue_struct *user_dlm_worker;
  
  
  
  /*
   * These are the ABI capabilities of dlmfs.
   *
   * Over time, dlmfs has added some features that were not part of the
   * initial ABI.  Unfortunately, some of these features are not detectable
   * via standard usage.  For example, Linux's default poll always returns
   * POLLIN, so there is no way for a caller of poll(2) to know when dlmfs
   * added poll support.  Instead, we provide this list of new capabilities.
   *
   * Capabilities is a read-only attribute.  We do it as a module parameter
   * so we can discover it whether dlmfs is built in, loaded, or even not
   * loaded.
   *
   * The ABI features are local to this machine's dlmfs mount.  This is
   * distinct from the locking protocol, which is concerned with inter-node
   * interaction.
   *
   * Capabilities:
   * - bast	: POLLIN against the file descriptor of a held lock
   *		  signifies a bast fired on the lock.
   */
  #define DLMFS_CAPABILITIES "bast stackglue"
  static int param_set_dlmfs_capabilities(const char *val,
  					struct kernel_param *kp)
  {
  	printk(KERN_ERR "%s: readonly parameter\n", kp->name);
  	return -EINVAL;
  }
  static int param_get_dlmfs_capabilities(char *buffer,
  					struct kernel_param *kp)
  {
  	return strlcpy(buffer, DLMFS_CAPABILITIES,
  		       strlen(DLMFS_CAPABILITIES) + 1);
  }
  module_param_call(capabilities, param_set_dlmfs_capabilities,
  		  param_get_dlmfs_capabilities, NULL, 0444);
  MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
  
  
  /*
   * decodes a set of open flags into a valid lock level and a set of flags.
   * returns < 0 if we have invalid flags
   * flags which mean something to us:
   * O_RDONLY -> PRMODE level
   * O_WRONLY -> EXMODE level
   *
   * O_NONBLOCK -> NOQUEUE
   */
  static int dlmfs_decode_open_flags(int open_flags,
  				   int *level,
  				   int *flags)
  {
  	if (open_flags & (O_WRONLY|O_RDWR))
  		*level = DLM_LOCK_EX;
  	else
  		*level = DLM_LOCK_PR;
  
  	*flags = 0;
  	if (open_flags & O_NONBLOCK)
  		*flags |= DLM_LKF_NOQUEUE;
  
  	return 0;
  }
  
  static int dlmfs_file_open(struct inode *inode,
  			   struct file *file)
  {
  	int status, level, flags;
  	struct dlmfs_filp_private *fp = NULL;
  	struct dlmfs_inode_private *ip;
  
  	if (S_ISDIR(inode->i_mode))
  		BUG();
  
  	mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
  		file->f_flags);
  
  	status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
  	if (status < 0)
  		goto bail;
  
  	/* We don't want to honor O_APPEND at read/write time as it
  	 * doesn't make sense for LVB writes. */
  	file->f_flags &= ~O_APPEND;
  
  	fp = kmalloc(sizeof(*fp), GFP_NOFS);
  	if (!fp) {
  		status = -ENOMEM;
  		goto bail;
  	}
  	fp->fp_lock_level = level;
  
  	ip = DLMFS_I(inode);
  
  	status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
  	if (status < 0) {
  		/* this is a strange error to return here but I want
  		 * to be able userspace to be able to distinguish a
  		 * valid lock request from one that simply couldn't be
  		 * granted. */
  		if (flags & DLM_LKF_NOQUEUE && status == -EAGAIN)
  			status = -ETXTBSY;
  		kfree(fp);
  		goto bail;
  	}
  
  	file->private_data = fp;
  bail:
  	return status;
  }
  
  static int dlmfs_file_release(struct inode *inode,
  			      struct file *file)
  {
  	int level, status;
  	struct dlmfs_inode_private *ip = DLMFS_I(inode);
  	struct dlmfs_filp_private *fp = file->private_data;
  
  	if (S_ISDIR(inode->i_mode))
  		BUG();
  
  	mlog(0, "close called on inode %lu\n", inode->i_ino);
  
  	status = 0;
  	if (fp) {
  		level = fp->fp_lock_level;
  		if (level != DLM_LOCK_IV)
  			user_dlm_cluster_unlock(&ip->ip_lockres, level);
  
  		kfree(fp);
  		file->private_data = NULL;
  	}
  
  	return 0;
  }
  
  /*
   * We do ->setattr() just to override size changes.  Our size is the size
   * of the LVB and nothing else.
   */
  static int dlmfs_file_setattr(struct dentry *dentry, struct iattr *attr)
  {
  	int error;
  	struct inode *inode = dentry->d_inode;
  
  	attr->ia_valid &= ~ATTR_SIZE;
  	error = inode_change_ok(inode, attr);
  	if (error)
  		return error;
  
  	setattr_copy(inode, attr);
  	mark_inode_dirty(inode);
  	return 0;
  }
  
  static unsigned int dlmfs_file_poll(struct file *file, poll_table *wait)
  {
  	int event = 0;
  	struct inode *inode = file_inode(file);
  	struct dlmfs_inode_private *ip = DLMFS_I(inode);
  
  	poll_wait(file, &ip->ip_lockres.l_event, wait);
  
  	spin_lock(&ip->ip_lockres.l_lock);
  	if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
  		event = POLLIN | POLLRDNORM;
  	spin_unlock(&ip->ip_lockres.l_lock);
  
  	return event;
  }
  
  static ssize_t dlmfs_file_read(struct file *filp,
  			       char __user *buf,
  			       size_t count,
  			       loff_t *ppos)
  {
  	int bytes_left;
  	ssize_t readlen, got;
  	char *lvb_buf;
  	struct inode *inode = file_inode(filp);
  
  	mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
  		inode->i_ino, count, *ppos);
  
  	if (*ppos >= i_size_read(inode))
  		return 0;
  
  	if (!count)
  		return 0;
  
  	if (!access_ok(VERIFY_WRITE, buf, count))
  		return -EFAULT;
  
  	/* don't read past the lvb */
  	if ((count + *ppos) > i_size_read(inode))
  		readlen = i_size_read(inode) - *ppos;
  	else
  		readlen = count;
  
  	lvb_buf = kmalloc(readlen, GFP_NOFS);
  	if (!lvb_buf)
  		return -ENOMEM;
  
  	got = user_dlm_read_lvb(inode, lvb_buf, readlen);
  	if (got) {
  		BUG_ON(got != readlen);
  		bytes_left = __copy_to_user(buf, lvb_buf, readlen);
  		readlen -= bytes_left;
  	} else
  		readlen = 0;
  
  	kfree(lvb_buf);
  
  	*ppos = *ppos + readlen;
  
  	mlog(0, "read %zd bytes\n", readlen);
  	return readlen;
  }
  
  static ssize_t dlmfs_file_write(struct file *filp,
  				const char __user *buf,
  				size_t count,
  				loff_t *ppos)
  {
  	int bytes_left;
  	ssize_t writelen;
  	char *lvb_buf;
  	struct inode *inode = file_inode(filp);
  
  	mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
  		inode->i_ino, count, *ppos);
  
  	if (*ppos >= i_size_read(inode))
  		return -ENOSPC;
  
  	if (!count)
  		return 0;
  
  	if (!access_ok(VERIFY_READ, buf, count))
  		return -EFAULT;
  
  	/* don't write past the lvb */
  	if ((count + *ppos) > i_size_read(inode))
  		writelen = i_size_read(inode) - *ppos;
  	else
  		writelen = count - *ppos;
  
  	lvb_buf = kmalloc(writelen, GFP_NOFS);
  	if (!lvb_buf)
  		return -ENOMEM;
  
  	bytes_left = copy_from_user(lvb_buf, buf, writelen);
  	writelen -= bytes_left;
  	if (writelen)
  		user_dlm_write_lvb(inode, lvb_buf, writelen);
  
  	kfree(lvb_buf);
  
  	*ppos = *ppos + writelen;
  	mlog(0, "wrote %zd bytes\n", writelen);
  	return writelen;
  }
  
  static void dlmfs_init_once(void *foo)
  {
  	struct dlmfs_inode_private *ip =
  		(struct dlmfs_inode_private *) foo;
  
  	ip->ip_conn = NULL;
  	ip->ip_parent = NULL;
  
  	inode_init_once(&ip->ip_vfs_inode);
  }
  
  static struct inode *dlmfs_alloc_inode(struct super_block *sb)
  {
  	struct dlmfs_inode_private *ip;
  
  	ip = kmem_cache_alloc(dlmfs_inode_cache, GFP_NOFS);
  	if (!ip)
  		return NULL;
  
  	return &ip->ip_vfs_inode;
  }
  
  static void dlmfs_i_callback(struct rcu_head *head)
  {
  	struct inode *inode = container_of(head, struct inode, i_rcu);
  	kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
  }
  
  static void dlmfs_destroy_inode(struct inode *inode)
  {
  	call_rcu(&inode->i_rcu, dlmfs_i_callback);
  }
  
  static void dlmfs_evict_inode(struct inode *inode)
  {
  	int status;
  	struct dlmfs_inode_private *ip;
  
  	clear_inode(inode);
  
  	mlog(0, "inode %lu\n", inode->i_ino);
  
  	ip = DLMFS_I(inode);
  
  	if (S_ISREG(inode->i_mode)) {
  		status = user_dlm_destroy_lock(&ip->ip_lockres);
  		if (status < 0)
  			mlog_errno(status);
  		iput(ip->ip_parent);
  		goto clear_fields;
  	}
  
  	mlog(0, "we're a directory, ip->ip_conn = 0x%p\n", ip->ip_conn);
  	/* we must be a directory. If required, lets unregister the
  	 * dlm context now. */
  	if (ip->ip_conn)
  		user_dlm_unregister(ip->ip_conn);
  clear_fields:
  	ip->ip_parent = NULL;
  	ip->ip_conn = NULL;
  }
  
  static struct inode *dlmfs_get_root_inode(struct super_block *sb)
  {
  	struct inode *inode = new_inode(sb);
  	umode_t mode = S_IFDIR | 0755;
  
  	if (inode) {
  		inode->i_ino = get_next_ino();
  		inode_init_owner(inode, NULL, mode);
  		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  		inc_nlink(inode);
  
  		inode->i_fop = &simple_dir_operations;
  		inode->i_op = &dlmfs_root_inode_operations;
  	}
  
  	return inode;
  }
  
  static struct inode *dlmfs_get_inode(struct inode *parent,
  				     struct dentry *dentry,
  				     umode_t mode)
  {
  	struct super_block *sb = parent->i_sb;
  	struct inode * inode = new_inode(sb);
  	struct dlmfs_inode_private *ip;
  
  	if (!inode)
  		return NULL;
  
  	inode->i_ino = get_next_ino();
  	inode_init_owner(inode, parent, mode);
  	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  
  	ip = DLMFS_I(inode);
  	ip->ip_conn = DLMFS_I(parent)->ip_conn;
  
  	switch (mode & S_IFMT) {
  	default:
  		/* for now we don't support anything other than
  		 * directories and regular files. */
  		BUG();
  		break;
  	case S_IFREG:
  		inode->i_op = &dlmfs_file_inode_operations;
  		inode->i_fop = &dlmfs_file_operations;
  
  		i_size_write(inode,  DLM_LVB_LEN);
  
  		user_dlm_lock_res_init(&ip->ip_lockres, dentry);
  
  		/* released at clear_inode time, this insures that we
  		 * get to drop the dlm reference on each lock *before*
  		 * we call the unregister code for releasing parent
  		 * directories. */
  		ip->ip_parent = igrab(parent);
  		BUG_ON(!ip->ip_parent);
  		break;
  	case S_IFDIR:
  		inode->i_op = &dlmfs_dir_inode_operations;
  		inode->i_fop = &simple_dir_operations;
  
  		/* directory inodes start off with i_nlink ==
  		 * 2 (for "." entry) */
  		inc_nlink(inode);
  		break;
  	}
  	return inode;
  }
  
  /*
   * File creation. Allocate an inode, and we're done..
   */
  /* SMP-safe */
  static int dlmfs_mkdir(struct inode * dir,
  		       struct dentry * dentry,
  		       umode_t mode)
  {
  	int status;
  	struct inode *inode = NULL;
  	struct qstr *domain = &dentry->d_name;
  	struct dlmfs_inode_private *ip;
  	struct ocfs2_cluster_connection *conn;
  
  	mlog(0, "mkdir %.*s\n", domain->len, domain->name);
  
  	/* verify that we have a proper domain */
  	if (domain->len >= GROUP_NAME_MAX) {
  		status = -EINVAL;
  		mlog(ML_ERROR, "invalid domain name for directory.\n");
  		goto bail;
  	}
  
  	inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
  	if (!inode) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	ip = DLMFS_I(inode);
  
  	conn = user_dlm_register(domain);
  	if (IS_ERR(conn)) {
  		status = PTR_ERR(conn);
  		mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
  		     status, domain->len, domain->name);
  		goto bail;
  	}
  	ip->ip_conn = conn;
  
  	inc_nlink(dir);
  	d_instantiate(dentry, inode);
  	dget(dentry);	/* Extra count - pin the dentry in core */
  
  	status = 0;
  bail:
  	if (status < 0)
  		iput(inode);
  	return status;
  }
  
  static int dlmfs_create(struct inode *dir,
  			struct dentry *dentry,
  			umode_t mode,
  			bool excl)
  {
  	int status = 0;
  	struct inode *inode;
  	struct qstr *name = &dentry->d_name;
  
  	mlog(0, "create %.*s\n", name->len, name->name);
  
  	/* verify name is valid and doesn't contain any dlm reserved
  	 * characters */
  	if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
  	    name->name[0] == '$') {
  		status = -EINVAL;
  		mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
  		     name->name);
  		goto bail;
  	}
  
  	inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
  	if (!inode) {
  		status = -ENOMEM;
  		mlog_errno(status);
  		goto bail;
  	}
  
  	d_instantiate(dentry, inode);
  	dget(dentry);	/* Extra count - pin the dentry in core */
  bail:
  	return status;
  }
  
  static int dlmfs_unlink(struct inode *dir,
  			struct dentry *dentry)
  {
  	int status;
  	struct inode *inode = dentry->d_inode;
  
  	mlog(0, "unlink inode %lu\n", inode->i_ino);
  
  	/* if there are no current holders, or none that are waiting
  	 * to acquire a lock, this basically destroys our lockres. */
  	status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
  	if (status < 0) {
  		mlog(ML_ERROR, "unlink %pd, error %d from destroy\n",
  		     dentry, status);
  		goto bail;
  	}
  	status = simple_unlink(dir, dentry);
  bail:
  	return status;
  }
  
  static int dlmfs_fill_super(struct super_block * sb,
  			    void * data,
  			    int silent)
  {
  	sb->s_maxbytes = MAX_LFS_FILESIZE;
  	sb->s_blocksize = PAGE_CACHE_SIZE;
  	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  	sb->s_magic = DLMFS_MAGIC;
  	sb->s_op = &dlmfs_ops;
  	sb->s_root = d_make_root(dlmfs_get_root_inode(sb));
  	if (!sb->s_root)
  		return -ENOMEM;
  	return 0;
  }
  
  static const struct file_operations dlmfs_file_operations = {
  	.open		= dlmfs_file_open,
  	.release	= dlmfs_file_release,
  	.poll		= dlmfs_file_poll,
  	.read		= dlmfs_file_read,
  	.write		= dlmfs_file_write,
  	.llseek		= default_llseek,
  };
  
  static const struct inode_operations dlmfs_dir_inode_operations = {
  	.create		= dlmfs_create,
  	.lookup		= simple_lookup,
  	.unlink		= dlmfs_unlink,
  };
  
  /* this way we can restrict mkdir to only the toplevel of the fs. */
  static const struct inode_operations dlmfs_root_inode_operations = {
  	.lookup		= simple_lookup,
  	.mkdir		= dlmfs_mkdir,
  	.rmdir		= simple_rmdir,
  };
  
  static const struct super_operations dlmfs_ops = {
  	.statfs		= simple_statfs,
  	.alloc_inode	= dlmfs_alloc_inode,
  	.destroy_inode	= dlmfs_destroy_inode,
  	.evict_inode	= dlmfs_evict_inode,
  	.drop_inode	= generic_delete_inode,
  };
  
  static const struct inode_operations dlmfs_file_inode_operations = {
  	.getattr	= simple_getattr,
  	.setattr	= dlmfs_file_setattr,
  };
  
  static struct dentry *dlmfs_mount(struct file_system_type *fs_type,
  	int flags, const char *dev_name, void *data)
  {
  	return mount_nodev(fs_type, flags, data, dlmfs_fill_super);
  }
  
  static struct file_system_type dlmfs_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "ocfs2_dlmfs",
  	.mount		= dlmfs_mount,
  	.kill_sb	= kill_litter_super,
  };
  MODULE_ALIAS_FS("ocfs2_dlmfs");
  
  static int __init init_dlmfs_fs(void)
  {
  	int status;
  	int cleanup_inode = 0, cleanup_worker = 0;
  
  	dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
  				sizeof(struct dlmfs_inode_private),
  				0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
  					SLAB_MEM_SPREAD),
  				dlmfs_init_once);
  	if (!dlmfs_inode_cache) {
  		status = -ENOMEM;
  		goto bail;
  	}
  	cleanup_inode = 1;
  
  	user_dlm_worker = create_singlethread_workqueue("user_dlm");
  	if (!user_dlm_worker) {
  		status = -ENOMEM;
  		goto bail;
  	}
  	cleanup_worker = 1;
  
  	user_dlm_set_locking_protocol();
  	status = register_filesystem(&dlmfs_fs_type);
  bail:
  	if (status) {
  		if (cleanup_inode)
  			kmem_cache_destroy(dlmfs_inode_cache);
  		if (cleanup_worker)
  			destroy_workqueue(user_dlm_worker);
  	} else
  		printk("OCFS2 User DLM kernel interface loaded\n");
  	return status;
  }
  
  static void __exit exit_dlmfs_fs(void)
  {
  	unregister_filesystem(&dlmfs_fs_type);
  
  	flush_workqueue(user_dlm_worker);
  	destroy_workqueue(user_dlm_worker);
  
  	/*
  	 * Make sure all delayed rcu free inodes are flushed before we
  	 * destroy cache.
  	 */
  	rcu_barrier();
  	kmem_cache_destroy(dlmfs_inode_cache);
  
  }
  
  MODULE_AUTHOR("Oracle");
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("OCFS2 DLM-Filesystem");
  
  module_init(init_dlmfs_fs)
  module_exit(exit_dlmfs_fs)
  