/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* locks.c
*
* Userspace file locking support
*
* Copyright (C) 2007 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.
*/
#include <linux/fs.h>
#define MLOG_MASK_PREFIX ML_INODE
#include <cluster/masklog.h>
#include "ocfs2.h"
#include "dlmglue.h"
#include "file.h"
#include "locks.h"
static int ocfs2_do_flock(struct file *file, struct inode *inode,
int cmd, struct file_lock *fl)
{
int ret = 0, level = 0, trylock = 0;
struct ocfs2_file_private *fp = file->private_data;
struct ocfs2_lock_res *lockres = &fp->fp_flock;
if (fl->fl_type == F_WRLCK)
level = 1;
if (!IS_SETLKW(cmd))
trylock = 1;
mutex_lock(&fp->fp_mutex);
if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
lockres->l_level > LKM_NLMODE) {
int old_level = 0;
if (lockres->l_level == LKM_EXMODE)
old_level = 1;
if (level == old_level)
goto out;
/*
* Converting an existing lock is not guaranteed to be
* atomic, so we can get away with simply unlocking
* here and allowing the lock code to try at the new
* level.
*/
flock_lock_file_wait(file,
&(struct file_lock){.fl_type = F_UNLCK});
ocfs2_file_unlock(file);
}
ret = ocfs2_file_lock(file, level, trylock);
if (ret) {
if (ret == -EAGAIN && trylock)
ret = -EWOULDBLOCK;
else
mlog_errno(ret);
goto out;
}
ret = flock_lock_file_wait(file, fl);
out:
mutex_unlock(&fp->fp_mutex);
return ret;
}
static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl)
{
int ret;
struct ocfs2_file_private *fp = file->private_data;
mutex_lock(&fp->fp_mutex);
ocfs2_file_unlock(file);
ret = flock_lock_file_wait(file, fl);
mutex_unlock(&fp->fp_mutex);
return ret;
}
/*
* Overall flow of ocfs2_flock() was influenced by gfs2_flock().
*/
int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl)
{
struct inode *inode = file->f_mapping->host;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
if (!(fl->fl_flags & FL_FLOCK))
return -ENOLCK;
if (__mandatory_lock(inode))
return -ENOLCK;
if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) ||
ocfs2_mount_local(osb))
return flock_lock_file_wait(file, fl);
if (fl->fl_type == F_UNLCK)
return ocfs2_do_funlock(file, cmd, fl);
else
return ocfs2_do_flock(file, inode, cmd, fl);
}
