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/* Hurd unionfs
Copyright (C) 2005 Free Software Foundation, Inc.
Written by Gianluca Guida <glguida@gmail.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 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 02111-1307
USA. */
/* Update thread: A clean way to solve locking issues of
root node update. */
#define _GNU_SOURCE
#include <errno.h>
#include <string.h>
#include <cthreads.h>
#include <rwlock.h>
#include "ncache.h"
#include "node.h"
#include "ulfs.h"
/* Reader lock is used by threads that are going to
add/remove an ulfs; writer lock is hold by the
update thread. */
static struct rwlock update_rwlock;
static struct condition update_wakeup;
static struct mutex update_lock;
static void
_root_update_thread ()
{
error_t err;
while (1)
{
if (hurd_condition_wait (&update_wakeup, &update_lock))
mutex_unlock (&update_lock);
rwlock_writer_lock (&update_rwlock);
do
{
ulfs_check();
err = node_init_root (netfs_root_node);
}
while (err == ENOENT);
if (err)
{
fprintf (stderr, "update thread: got a %s\n", strerror (err));
}
ncache_reset ();
rwlock_writer_unlock (&update_rwlock);
}
}
void
root_update_schedule ()
{
condition_signal (&update_wakeup);
}
void
root_update_disable ()
{
rwlock_reader_lock (&update_rwlock);
}
void
root_update_enable ()
{
rwlock_reader_unlock (&update_rwlock);
}
void
root_update_init()
{
mutex_init (&update_lock);
rwlock_init (&update_rwlock);
condition_init (&update_wakeup);
cthread_detach (cthread_fork ( (cthread_fn_t)_root_update_thread, 0));
}
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