/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* Utility routines and top-level conflict detection code for NBMAND
* locks.
*/
#include <sys/nbmlock.h>
#include <sys/rwlock.h>
#include <sys/vnode.h>
#include <sys/cmn_err.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <sys/vfs.h>
/*
* Enter the critical region for synchronizing I/O requests with lock/share
* requests. "mode" specifies whether the caller intends to update
* lock/share state (as opposed to just query it).
*/
void
nbl_start_crit(vnode_t *vp, krw_t mode)
{
rw_enter(&vp->v_nbllock, mode);
}
/*
* Leave the critical region.
*/
void
nbl_end_crit(vnode_t *vp)
{
rw_exit(&vp->v_nbllock);
}
/*
* Return non-zero if some thread is in the critical region.
* Note that this is appropriate for use in ASSERT()s only.
*/
int
nbl_in_crit(vnode_t *vp)
{
return (RW_LOCK_HELD(&vp->v_nbllock));
}
/*
* Returns non-zero if we need to look further for an NBMAND lock or
* share conflict.
*/
int
nbl_need_check(vnode_t *vp)
{
/*
* Currently we only check if NBMAND locks/shares are allowed on
* the filesystem. An option for the future would be to have a
* flag on the vnode, though the locking for that can get tricky.
*/
return ((vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND));
}
/*
* Top-level conflict detection routine. The arguments describe the
* operation that is being attempted. If the operation conflicts with an
* existing lock or share reservation, a non-zero value is returned. If
* the operation is allowed, zero is returned. Note that there is an
* implicit argument, which is the process ID of the requester.
*
* svmand indicates that the file has System V mandatory locking enabled,
* so we should look at all record locks, not just NBMAND record locks.
* (This is to avoid a deadlock between a process making an I/O request and
* a process trying to release a lock. Instead of letting the first
* process block in the filesystem code, we flag a conflict here.)
*/
int
nbl_conflict(vnode_t *vp,
nbl_op_t op, /* attempted operation */
u_offset_t offset, /* ignore if not I/O */
ssize_t length, /* ignore if not I/O */
int svmand, /* System V mandatory locking */
caller_context_t *ct) /* caller context */
{
ASSERT(nbl_in_crit(vp));
ASSERT(op == NBL_READ || op == NBL_WRITE || op == NBL_RENAME ||
op == NBL_REMOVE || op == NBL_READWRITE);
if (nbl_share_conflict(vp, op, ct)) {
return (1);
}
/*
* If this is not an I/O request, there's no need to check against
* the locks on the file.
*/
if (op == NBL_REMOVE || op == NBL_RENAME)
return (0);
return (nbl_lock_conflict(vp, op, offset, length, svmand, ct));
}
/*
* Determine if the given file has mode bits for System V mandatory locks.
* If there was an error, the errno value is returned. Otherwise, zero is
* returned and *svp is set appropriately (non-zero for mandatory locks,
* zero for no mandatory locks).
*/
int
nbl_svmand(vnode_t *vp, cred_t *cr, int *svp)
{
struct vattr va;
int error;
va.va_mask = AT_MODE;
error = VOP_GETATTR(vp, &va, 0, cr, NULL);
if (error != 0)
return (error);
*svp = MANDLOCK(vp, va.va_mode);
return (0);
}