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/*
Copyright (C) 1999 Free Software Foundation, Inc.
Written by Thomas Bushnell, BSG.
This file is part of the GNU Hurd.
The GNU Hurd 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, or (at
your option) any later version.
The GNU Hurd 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, USA. */
#include "priv.h"
/* Unlock node NP and release a hard reference; if this is the last
hard reference and there are no links to the file then request
soft references to be dropped. */
void
diskfs_nput (struct node *np)
{
int tried_drop_softrefs = 0;
loop:
spin_lock (&diskfs_node_refcnt_lock);
assert (np->references);
np->references--;
if (np->references + np->light_references == 0)
diskfs_drop_node (np);
else if (np->references == 0 && !tried_drop_softrefs)
{
spin_unlock (&diskfs_node_refcnt_lock);
diskfs_lost_hardrefs (np);
if (!np->dn_stat.st_nlink)
{
/* There are no links. If there are soft references that
can be dropped, we can't let them postpone deallocation.
So attempt to drop them. But that's a user-supplied
routine, which might result in further recursive calls to
the ref-counting system. So we have to reacquire our
reference around the call to forestall disaster. */
spin_lock (&diskfs_node_refcnt_lock);
np->references++;
spin_unlock (&diskfs_node_refcnt_lock);
diskfs_try_dropping_softrefs (np);
/* But there's no value in looping forever in this
routine; only try to drop soft refs once. */
tried_drop_softrefs = 1;
/* Now we can drop the reference back... */
goto loop;
}
mutex_unlock (&np->lock);
}
else
{
spin_unlock (&diskfs_node_refcnt_lock);
mutex_unlock (&np->lock);
}
}
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