root/fs/ocfs2/locks.c

DEFINITIONS

1. ocfs2_do_flock
2. ocfs2_do_funlock
3. ocfs2_flock
4. ocfs2_lock

/* -*- 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>
#include <linux/fcntl.h>

#define MLOG_MASK_PREFIX ML_INODE
#include <cluster/masklog.h>

#include "ocfs2.h"

#include "dlmglue.h"
#include "file.h"
#include "inode.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);
}

int ocfs2_lock(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_POSIX))
                return -ENOLCK;
        if (__mandatory_lock(inode))
                return -ENOLCK;

        return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl);
}