/*
  Copyright (c) 2006, 2007, 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
  This file is part of GlusterFS.

  GlusterFS 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 3 of the License,
  or (at your option) any later version.

  GlusterFS 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, see
  <http://www.gnu.org/licenses/>.
*/

#ifndef _CONFIG_H
#define _CONFIG_H
#include "config.h"
#endif

#include "glusterfs.h"
#include "compat.h"
#include "xlator.h"
#include "inode.h"
#include "logging.h"
#include "common-utils.h"
#include "list.h"

#include "locks.h"
#include "common.h"



static int
delete_locks_of_transport (pl_inode_t *pinode, transport_t *trans)
{
	posix_lock_t *tmp = NULL;
	posix_lock_t *l = NULL;

	list_for_each_entry_safe (l, tmp, &pinode->dir_list, list) {
		if (l->transport == trans) {
			__delete_lock (pinode, tmp);
			__destroy_lock (tmp);
		}
	}

	return 0;
}


/**
 * pl_inodelk: 
 *
 * This fop provides fcntl-style locking on files for internal
 * purposes. Locks held through this fop reside in a domain different
 * from those held by applications. This fop is for the use of AFR.
 */

int
pl_inodelk (call_frame_t *frame, xlator_t *this,
	    const char *volume, loc_t *loc, int32_t cmd, struct flock *flock)
{
	int32_t op_ret   = -1;
	int32_t op_errno = 0;
	int     ret      = -1;
	int     can_block = 0;
	posix_locks_private_t * priv       = NULL;
	transport_t *           transport  = NULL;
	pid_t                   client_pid = -1;
	pl_inode_t *            pinode     = NULL;
	posix_lock_t *          reqlock    = NULL;

	VALIDATE_OR_GOTO (frame, out);
	VALIDATE_OR_GOTO (loc, out);
	VALIDATE_OR_GOTO (flock, out);
	
	if ((flock->l_start < 0) || (flock->l_len < 0)) {
		op_errno = EINVAL;
		goto unwind;
	}

	transport  = frame->root->trans;
	client_pid = frame->root->pid;

	priv = (posix_locks_private_t *) this->private;

	VALIDATE_OR_GOTO (priv, out);

	pinode = pl_inode_get (this, loc->inode);
	if (!pinode) {
		gf_log (this->name, GF_LOG_ERROR,
			"out of memory :(");
		op_errno = ENOMEM;
		goto unwind;
	}

	if (client_pid == 0) {
		/* 
		   special case: this means release all locks 
		   from this transport
		*/
		gf_log (this->name, GF_LOG_DEBUG,
			"releasing all locks from transport %p", transport);

		delete_locks_of_transport (pinode, transport);
		goto unwind;
	}

	reqlock = new_posix_lock (flock, transport, client_pid);
	if (!reqlock) {
		gf_log (this->name, GF_LOG_ERROR,
			"out of memory :(");
		op_ret = -1;
		op_errno = ENOMEM;
		goto unwind;
	}

	switch (cmd) {
	case F_SETLKW:
		can_block = 1;
		reqlock->frame = frame;
		reqlock->this  = this;

		/* fall through */

	case F_SETLK:
		memcpy (&reqlock->user_flock, flock, sizeof (struct flock));
		ret = pl_setlk (this, pinode, reqlock,
				can_block, GF_LOCK_INTERNAL);

		if (ret == -1) {
			if (can_block)
				goto out;

			gf_log (this->name, GF_LOG_DEBUG, "returning EAGAIN");
			op_errno = EAGAIN;
			__destroy_lock (reqlock);
			goto unwind;
		}
		break;

	default:
		op_errno = ENOTSUP;
		gf_log (this->name, GF_LOG_ERROR,
			"lock command F_GETLK not supported for GF_FILE_LK (cmd=%d)", 
			cmd);
			goto unwind;
	}

	op_ret = 0;

unwind:	
	STACK_UNWIND (frame, op_ret, op_errno);
out:
	return 0;
}


int
pl_finodelk (call_frame_t *frame, xlator_t *this,
	     const char *volume, fd_t *fd, int32_t cmd, struct flock *flock)
{
	int32_t op_ret   = -1;
	int32_t op_errno = 0;
	int     ret      = -1;
	int     can_block = 0;
	posix_locks_private_t * priv       = NULL;
	transport_t *           transport  = NULL;
	pid_t                   client_pid = -1;
	pl_inode_t *            pinode     = NULL;
	posix_lock_t *          reqlock    = NULL;

	VALIDATE_OR_GOTO (frame, out);
	VALIDATE_OR_GOTO (fd, out);
	VALIDATE_OR_GOTO (flock, out);
	
	if ((flock->l_start < 0) || (flock->l_len < 0)) {
		op_errno = EINVAL;
		goto unwind;
	}

	transport  = frame->root->trans;
	client_pid = frame->root->pid;

	priv = (posix_locks_private_t *) this->private;

	VALIDATE_OR_GOTO (priv, out);

	pinode = pl_inode_get (this, fd->inode);
	if (!pinode) {
		gf_log (this->name, GF_LOG_ERROR,
			"out of memory :(");
		op_errno = ENOMEM;
		goto unwind;
	}

	if (client_pid == 0) {
		/* 
		   special case: this means release all locks 
		   from this transport
		*/
		gf_log (this->name, GF_LOG_DEBUG,
			"releasing all locks from transport %p", transport);

		delete_locks_of_transport (pinode, transport);
		goto unwind;
	}

	reqlock = new_posix_lock (flock, transport, client_pid);
	if (!reqlock) {
		gf_log (this->name, GF_LOG_ERROR,
			"out of memory :(");
		op_ret = -1;
		op_errno = ENOMEM;
		goto unwind;
	}

	switch (cmd) {
	case F_SETLKW:
		can_block = 1;
		reqlock->frame = frame;
		reqlock->this  = this;
		reqlock->fd    = fd;

		/* fall through */

	case F_SETLK:
		memcpy (&reqlock->user_flock, flock, sizeof (struct flock));
		ret = pl_setlk (this, pinode, reqlock,
				can_block, GF_LOCK_INTERNAL);

		if (ret == -1) {
			if (can_block)
				goto out;

			gf_log (this->name, GF_LOG_DEBUG, "returning EAGAIN");
			op_errno = EAGAIN;
			__destroy_lock (reqlock);
			goto unwind;
		}
		break;

	default:
		op_errno = ENOTSUP;
		gf_log (this->name, GF_LOG_ERROR,
			"lock command F_GETLK not supported for GF_FILE_LK (cmd=%d)", 
			cmd);
			goto unwind;
	}

	op_ret = 0;

unwind:	
	STACK_UNWIND (frame, op_ret, op_errno);
out:
	return 0;
}


/**
 * types_conflict - do two types of lock conflict?
 * @t1: type
 * @t2: type
 *
 * two read locks do not conflict
 * any other case conflicts
 */

static int
types_conflict (entrylk_type t1, entrylk_type t2)
{
	return !((t1 == ENTRYLK_RDLCK) && (t2 == ENTRYLK_RDLCK));
}

/**
 * all_names - does a basename represent all names?
 * @basename: name to check
 */

#define all_names(basename) ((basename == NULL) ? 1 : 0)

/**
 * names_conflict - do two names conflict?
 * @n1: name
 * @n2: name
 */

static int 
names_conflict (const char *n1, const char *n2)
{
	return all_names (n1) || all_names (n2) || !strcmp (n1, n2);
}


static int 
names_equal (const char *n1, const char *n2)
{
	return (n1 == NULL && n2 == NULL) || (n1 && n2 && !strcmp (n1, n2));
}

/**
 * lock_grantable - is this lock grantable?
 * @inode: inode in which to look
 * @basename: name we're trying to lock
 * @type: type of lock
 */

static pl_entry_lock_t *
__lock_grantable (pl_inode_t *pinode, const char *basename, entrylk_type type)
{
	pl_entry_lock_t *lock = NULL;

	if (list_empty (&pinode->dir_list))
		return NULL;

	list_for_each_entry (lock, &pinode->dir_list, inode_list) {
		if (names_conflict (lock->basename, basename) &&
		    types_conflict (lock->type, type))
			return lock;
	}

	return NULL;
}

/**
 * find_most_matching_lock - find the lock struct which most matches in order of:
 *                           lock on the exact basename ||
 *                           an all_names lock
 *                      
 *
 * @inode: inode in which to look
 * @basename: name to search for
 */

static pl_entry_lock_t * 
__find_most_matching_lock (pl_inode_t *pinode, const char *basename)
{
	pl_entry_lock_t *lock;
	pl_entry_lock_t *all = NULL;
	pl_entry_lock_t *exact = NULL;

	if (list_empty (&pinode->dir_list)) 
		return NULL;

	list_for_each_entry (lock, &pinode->dir_list, inode_list) {
		if (all_names (lock->basename))
			all = lock;
		else if (names_equal (lock->basename, basename))
			exact = lock;
	}

	return (exact ? exact : all);
}


/**
 * insert_new_lock - insert a new dir lock into the inode with the given parameters
 * @pinode: inode to insert into
 * @basename: basename for the lock
 * @type: type of the lock
 */

static pl_entry_lock_t *
new_entrylk_lock (pl_inode_t *pinode, const char *basename, entrylk_type type,
		  transport_t *trans)
{
	pl_entry_lock_t *newlock = NULL;

	newlock = CALLOC (sizeof (pl_entry_lock_t), 1);
	if (!newlock) {
		goto out;
	}

	newlock->basename = basename ? strdup (basename) : NULL;
	newlock->type     = type;
	newlock->trans    = trans;

	if (type == ENTRYLK_RDLCK)
		newlock->read_count = 1;

	INIT_LIST_HEAD (&newlock->inode_list);
	INIT_LIST_HEAD (&newlock->blocked_locks);

out:
	return newlock;
}

/**
 * lock_name - lock a name in a directory
 * @inode: inode for the directory in which to lock
 * @basename: name of the entry to lock
 *            if null, lock the entire directory
 *            
 * the entire directory being locked is represented as: a single
 * pl_entry_lock_t present in the entrylk_locks list with its
 * basename = NULL
 */

int
__lock_name (pl_inode_t *pinode, const char *basename, entrylk_type type,
	     call_frame_t *frame, xlator_t *this, int nonblock)
{
	pl_entry_lock_t *lock    = NULL;
	pl_entry_lock_t *conf    = NULL;

	transport_t *trans = NULL;

	int ret = -EINVAL;

	trans = frame->root->trans;

	conf = __lock_grantable (pinode, basename, type);
	if (conf) {
		ret = -EAGAIN;
		if (nonblock)
			goto out;

		lock = new_entrylk_lock (pinode, basename, type, trans);

		if (!lock) {
			ret = -ENOMEM;
			goto out;
		}

		gf_log (this->name, GF_LOG_DEBUG,
			"blocking lock: {pinode=%p, basename=%s}",
			pinode, basename);

		lock->frame   = frame;
		lock->this    = this;
		lock->blocked = 1;

		list_add (&lock->blocked_locks, &conf->blocked_locks);


		goto out;
	}
		
	switch (type) {
	case ENTRYLK_RDLCK:
		lock = __find_most_matching_lock (pinode, basename);

		if (lock && names_equal (lock->basename, basename)) {
			lock->read_count++;

			FREE (lock->basename);
			FREE (lock);

			lock = NULL;
		} else {
			lock = new_entrylk_lock (pinode, basename, type, trans);

			if (!lock) {
				ret = -ENOMEM;
				goto out;
			}

			list_add (&lock->inode_list, &pinode->dir_list);
		}
		break;

	case ENTRYLK_WRLCK:
		lock = new_entrylk_lock (pinode, basename, type, trans);
			
		if (!lock) {
			ret = -ENOMEM;
			goto out;
		}

		list_add (&lock->inode_list, &pinode->dir_list);
		break;
	}

	ret = 0;
out:
	return ret;
}


/**
 * unlock_name - unlock a name in a directory
 * @inode: inode for the directory to unlock in
 * @basename: name of the entry to unlock
 *            if null, unlock the entire directory
 */

pl_entry_lock_t *
__unlock_name (pl_inode_t *pinode, const char *basename, entrylk_type type)
{
	pl_entry_lock_t *lock = NULL;
	pl_entry_lock_t *ret_lock = NULL;

	lock = __find_most_matching_lock (pinode, basename);
	
	if (!lock) {
		gf_log ("locks", GF_LOG_DEBUG,
			"unlock on %s (type=%s) attempted but no matching lock found",
			basename, type == ENTRYLK_RDLCK ? "ENTRYLK_RDLCK" : 
			"ENTRYLK_WRLCK");
		goto out;
	}
	
	if (names_equal (lock->basename, basename)
	    && lock->type == type) {
		if (type == ENTRYLK_RDLCK) {
			lock->read_count--;
		}
		if (type == ENTRYLK_WRLCK || lock->read_count == 0) {
			list_del (&lock->inode_list);
			ret_lock = lock;
		}
	} else {
		gf_log ("locks", GF_LOG_ERROR,
			"unlock for a non-existing lock!");
		goto out;
	}

out:
	return ret_lock;
}


void
__grant_blocked_entry_locks (xlator_t *this, pl_inode_t *pl_inode,
			     pl_entry_lock_t *lock,
			     struct list_head *granted)
{
	int              bl_ret = 0;
	pl_entry_lock_t *bl   = NULL;
	pl_entry_lock_t *tmp  = NULL;

	list_for_each_entry_safe (bl, tmp, &lock->blocked_locks, 
				  blocked_locks) {
		list_del_init (&bl->blocked_locks);

		/* TODO: error checking */

		gf_log ("locks", GF_LOG_DEBUG,
			"trying to unblock: {pinode=%p, basename=%s}",
			pl_inode, bl->basename);
					
		bl_ret = __lock_name (pl_inode, bl->basename, bl->type,
				      bl->frame, bl->this, 0);

		if (bl_ret == 0) {
			list_add (&bl->blocked_locks, granted);
		} else {
			if (bl->basename)
				FREE (bl->basename);
			FREE (bl);
		}
	}	
	return;
}


void
grant_blocked_entry_locks (xlator_t *this, pl_inode_t *pl_inode,
			   pl_entry_lock_t *unlocked)
{
	struct list_head  granted_list;
	pl_entry_lock_t  *tmp = NULL;
	pl_entry_lock_t  *lock = NULL;

	INIT_LIST_HEAD (&granted_list);

	pthread_mutex_lock (&pl_inode->mutex);
	{
		__grant_blocked_entry_locks (this, pl_inode, unlocked,
					     &granted_list);
	}
	pthread_mutex_unlock (&pl_inode->mutex);

	list_for_each_entry_safe (lock, tmp, &granted_list, blocked_locks) {
		list_del_init (&lock->blocked_locks);

		STACK_UNWIND (lock->frame, 0, 0);

		FREE (lock->basename);
		FREE (lock);
	}

	FREE (unlocked->basename);
	FREE (unlocked);

	return;
}


/**
 * release_entry_locks_for_transport: release all entry locks from this
 * transport for this loc_t
 */

static int
release_entry_locks_for_transport (xlator_t *this, pl_inode_t *pinode,
				   transport_t *trans)
{
	pl_entry_lock_t  *lock;
	pl_entry_lock_t  *tmp;
	struct list_head  granted;

	INIT_LIST_HEAD (&granted);

	pthread_mutex_lock (&pinode->mutex);
	{
		if (list_empty (&pinode->dir_list)) {
			goto unlock;
		}

		list_for_each_entry_safe (lock, tmp, &pinode->dir_list,
					  inode_list) {
			if (lock->trans != trans)
				continue;

			list_del_init (&lock->inode_list);
			__grant_blocked_entry_locks (this, pinode, lock,
						     &granted);

			FREE (lock->basename);
			FREE (lock);
		}
	}
unlock:
	pthread_mutex_unlock (&pinode->mutex);

	list_for_each_entry_safe (lock, tmp, &granted, blocked_locks) {
		list_del_init (&lock->blocked_locks);

		STACK_UNWIND (lock->frame, 0, 0);

		FREE (lock->basename);
		FREE (lock);
	}

	return 0;
}


/**
 * pl_entrylk:
 * 
 * Locking on names (directory entries)
 */

int
pl_entrylk (call_frame_t *frame, xlator_t *this,
	    const char *volume, loc_t *loc, const char *basename, 
	    entrylk_cmd cmd, entrylk_type type)
{
	int32_t op_ret   = -1;
	int32_t op_errno = 0;

	transport_t * transport = NULL;
	pid_t pid = -1;

	pl_inode_t *       pinode = NULL; 
	int                ret    = -1;
	pl_entry_lock_t   *unlocked = NULL;
	char               unwind = 1;


	pinode = pl_inode_get (this, loc->inode);
	if (!pinode) {
		gf_log (this->name, GF_LOG_ERROR,
			"out of memory :(");
		op_errno = ENOMEM;
		goto out;
	}

	pid       = frame->root->pid;
	transport = frame->root->trans;

	if (pid == 0) {
		/* 
		   this is a special case that means release
		   all locks from this transport 
		*/

		gf_log (this->name, GF_LOG_DEBUG,
			"releasing locks for transport %p", transport);

		release_entry_locks_for_transport (this, pinode, transport);
		op_ret = 0;

		goto out;
	}

	switch (cmd) {
	case ENTRYLK_LOCK:
		pthread_mutex_lock (&pinode->mutex);
		{
			ret = __lock_name (pinode, basename, type,
					   frame, this, 0);
		}
		pthread_mutex_unlock (&pinode->mutex);

		if (ret < 0) {
			if (ret == -EAGAIN)
				unwind = 0;
			op_errno = -ret;
			goto out;
		}

		break;

	case ENTRYLK_LOCK_NB:
		pthread_mutex_lock (&pinode->mutex);
		{
			ret = __lock_name (pinode, basename, type,
					   frame, this, 1);
		}
		pthread_mutex_unlock (&pinode->mutex);

		if (ret < 0) {
			op_errno = -ret;
			goto out;
		}

		break;

	case ENTRYLK_UNLOCK:
		pthread_mutex_lock (&pinode->mutex);
		{
			unlocked = __unlock_name (pinode, basename, type);
		}
		pthread_mutex_unlock (&pinode->mutex);

		if (unlocked)
			grant_blocked_entry_locks (this, pinode, unlocked);

		break;

	default:
		gf_log (this->name, GF_LOG_ERROR,
			"unexpected case!");
		goto out;
	}

	op_ret = 0;
out:
	if (unwind) {
		STACK_UNWIND (frame, op_ret, op_errno);
	}
	
	return 0;
}


/**
 * pl_entrylk:
 * 
 * Locking on names (directory entries)
 */

int
pl_fentrylk (call_frame_t *frame, xlator_t *this,
	     const char *volume, fd_t *fd, const char *basename, 
	     entrylk_cmd cmd, entrylk_type type)
{
	int32_t op_ret   = -1;
	int32_t op_errno = 0;

	transport_t * transport = NULL;
	pid_t pid = -1;

	pl_inode_t *       pinode = NULL; 
	int                ret    = -1;
	pl_entry_lock_t   *unlocked = NULL;
	char               unwind = 1;

	pinode = pl_inode_get (this, fd->inode);
	if (!pinode) {
		gf_log (this->name, GF_LOG_ERROR,
			"out of memory :(");
		goto out;
	}

	pid       = frame->root->pid;
	transport = frame->root->trans;

	if (pid == 0) {
		/* 
		   this is a special case that means release
		   all locks from this transport 
		*/

		gf_log (this->name, GF_LOG_DEBUG,
			"releasing locks for transport %p", transport);

		release_entry_locks_for_transport (this, pinode, transport);
		op_ret = 0;
		goto out;
	}

	switch (cmd) {
	case ENTRYLK_LOCK:
		pthread_mutex_lock (&pinode->mutex);
		{
			ret = __lock_name (pinode, basename, type,
					   frame, this, 0);
		}
		pthread_mutex_unlock (&pinode->mutex);

		if (ret < 0) {
			if (ret == -EAGAIN)
				unwind = 0;
			op_errno = -ret;
			goto out;
		}
		break;

	case ENTRYLK_LOCK_NB:
		pthread_mutex_lock (&pinode->mutex);
		{
			ret = __lock_name (pinode, basename, type,
					   frame, this, 1);
		}
		pthread_mutex_unlock (&pinode->mutex);

		if (ret < 0) {
			op_errno = -ret;
			goto out;
		}
		break;

	case ENTRYLK_UNLOCK:
		pthread_mutex_lock (&pinode->mutex);
		{
			unlocked = __unlock_name (pinode, basename, type);
		}
		pthread_mutex_unlock (&pinode->mutex);

		if (unlocked)
			grant_blocked_entry_locks (this, pinode, unlocked);
		break;

	default:
		gf_log (this->name, GF_LOG_ERROR,
			"unexpected case!");
		goto out;
	}

	op_ret = 0;
out:
	if (unwind) {
		STACK_UNWIND (frame, op_ret, op_errno);
	}
	
	return 0;
}