diff options
Diffstat (limited to 'libdiskfs/node-nput.c')
-rw-r--r-- | libdiskfs/node-nput.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/libdiskfs/node-nput.c b/libdiskfs/node-nput.c new file mode 100644 index 00000000..425b2216 --- /dev/null +++ b/libdiskfs/node-nput.c @@ -0,0 +1,69 @@ +/* + 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); + } +} |