freebsd-nq/sys/sys/lockf.h
Pedro F. Giffuni 51369649b0 sys: further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
2017-11-20 19:43:44 +00:00

136 lines
5.6 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Scooter Morris at Genentech Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)lockf.h 8.1 (Berkeley) 6/11/93
* $FreeBSD$
*/
#ifndef _SYS_LOCKF_H_
#define _SYS_LOCKF_H_
#include <sys/queue.h>
#include <sys/_lock.h>
#include <sys/_sx.h>
struct flock;
struct vop_advlock_args;
struct vop_advlockasync_args;
/*
* The lockf_entry structure is a kernel structure which contains the
* information associated with a byte range lock. The lockf_entry
* structures are linked into the inode structure. Locks are sorted by
* the starting byte of the lock for efficiency.
*
* Active and pending locks on a vnode are organised into a
* graph. Each pending lock has an out-going edge to each active lock
* that blocks it.
*
* Locks:
* (i) locked by the vnode interlock
* (s) locked by state->ls_lock
* (S) locked by lf_lock_states_lock
* (c) const until freeing
*/
struct lockf_edge {
LIST_ENTRY(lockf_edge) le_outlink; /* (s) link from's out-edge list */
LIST_ENTRY(lockf_edge) le_inlink; /* (s) link to's in-edge list */
struct lockf_entry *le_from; /* (c) out-going from here */
struct lockf_entry *le_to; /* (s) in-coming to here */
};
LIST_HEAD(lockf_edge_list, lockf_edge);
struct lockf_entry {
short lf_flags; /* (c) Semantics: F_POSIX, F_FLOCK, F_WAIT */
short lf_type; /* (s) Lock type: F_RDLCK, F_WRLCK */
off_t lf_start; /* (s) Byte # of the start of the lock */
off_t lf_end; /* (s) Byte # of the end of the lock (OFF_MAX=EOF) */
struct lock_owner *lf_owner; /* (c) Owner of the lock */
struct vnode *lf_vnode; /* (c) File being locked (only valid for active lock) */
struct inode *lf_inode; /* (c) Back pointer to the inode */
struct task *lf_async_task;/* (c) Async lock callback */
LIST_ENTRY(lockf_entry) lf_link; /* (s) Linkage for lock lists */
struct lockf_edge_list lf_outedges; /* (s) list of out-edges */
struct lockf_edge_list lf_inedges; /* (s) list of out-edges */
int lf_refs; /* (s) ref count */
};
LIST_HEAD(lockf_entry_list, lockf_entry);
/*
* Extra lf_flags bits used by the implementation
*/
#define F_INTR 0x8000 /* lock was interrupted by lf_purgelocks */
/*
* Filesystem private node structures should include space for a
* pointer to a struct lockf_state. This pointer is used by the lock
* manager to track the locking state for a file.
*
* The ls_active list contains the set of active locks on the file. It
* is strictly ordered by the lock's lf_start value. Each active lock
* will have in-coming edges to any pending lock which it blocks.
*
* Lock requests which are blocked by some other active lock are
* listed in ls_pending with newer requests first in the list. Lock
* requests in this list will have out-going edges to each active lock
* that blocks then. They will also have out-going edges to each
* pending lock that is older in the queue - this helps to ensure
* fairness when several processes are contenting to lock the same
* record.
* The value of ls_threads is the number of threads currently using
* the state structure (typically either setting/clearing locks or
* sleeping waiting to do so). This is used to defer freeing the
* structure while some thread is still using it.
*/
struct lockf {
LIST_ENTRY(lockf) ls_link; /* (S) all active lockf states */
struct sx ls_lock;
struct lockf_entry_list ls_active; /* (s) Active locks */
struct lockf_entry_list ls_pending; /* (s) Pending locks */
int ls_threads; /* (i) Thread count */
};
LIST_HEAD(lockf_list, lockf);
typedef int lf_iterator(struct vnode *, struct flock *, void *);
int lf_advlock(struct vop_advlock_args *, struct lockf **, u_quad_t);
int lf_advlockasync(struct vop_advlockasync_args *, struct lockf **, u_quad_t);
void lf_purgelocks(struct vnode *vp, struct lockf **statep);
int lf_iteratelocks_sysid(int sysid, lf_iterator *, void *);
int lf_iteratelocks_vnode(struct vnode *vp, lf_iterator *, void *);
int lf_countlocks(int sysid);
void lf_clearremotesys(int sysid);
#endif /* !_SYS_LOCKF_H_ */