xref: /titanic_50/usr/src/uts/common/fs/nbmlock.c (revision da6c28aaf62fa55f0fdb8004aa40f88f23bf53f0)
17c478bd9Sstevel@tonic-gate /*
27c478bd9Sstevel@tonic-gate  * CDDL HEADER START
37c478bd9Sstevel@tonic-gate  *
47c478bd9Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*da6c28aaSamw  * Common Development and Distribution License (the "License").
6*da6c28aaSamw  * You may not use this file except in compliance with the License.
77c478bd9Sstevel@tonic-gate  *
87c478bd9Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
97c478bd9Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
107c478bd9Sstevel@tonic-gate  * See the License for the specific language governing permissions
117c478bd9Sstevel@tonic-gate  * and limitations under the License.
127c478bd9Sstevel@tonic-gate  *
137c478bd9Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
147c478bd9Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
157c478bd9Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
167c478bd9Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
177c478bd9Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
187c478bd9Sstevel@tonic-gate  *
197c478bd9Sstevel@tonic-gate  * CDDL HEADER END
207c478bd9Sstevel@tonic-gate  */
217c478bd9Sstevel@tonic-gate /*
22*da6c28aaSamw  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
23*da6c28aaSamw  * Use is subject to license terms.
247c478bd9Sstevel@tonic-gate  */
257c478bd9Sstevel@tonic-gate 
267c478bd9Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
277c478bd9Sstevel@tonic-gate 
287c478bd9Sstevel@tonic-gate /*
297c478bd9Sstevel@tonic-gate  * Utility routines and top-level conflict detection code for NBMAND
307c478bd9Sstevel@tonic-gate  * locks.
317c478bd9Sstevel@tonic-gate  */
327c478bd9Sstevel@tonic-gate 
337c478bd9Sstevel@tonic-gate #include <sys/nbmlock.h>
347c478bd9Sstevel@tonic-gate #include <sys/rwlock.h>
357c478bd9Sstevel@tonic-gate #include <sys/vnode.h>
367c478bd9Sstevel@tonic-gate #include <sys/cmn_err.h>
377c478bd9Sstevel@tonic-gate #include <sys/types.h>
387c478bd9Sstevel@tonic-gate #include <sys/fcntl.h>
397c478bd9Sstevel@tonic-gate #include <sys/vfs.h>
407c478bd9Sstevel@tonic-gate 
417c478bd9Sstevel@tonic-gate /*
427c478bd9Sstevel@tonic-gate  * Enter the critical region for synchronizing I/O requests with lock/share
437c478bd9Sstevel@tonic-gate  * requests.  "mode" specifies whether the caller intends to update
447c478bd9Sstevel@tonic-gate  * lock/share state (as opposed to just query it).
457c478bd9Sstevel@tonic-gate  */
467c478bd9Sstevel@tonic-gate 
477c478bd9Sstevel@tonic-gate void
487c478bd9Sstevel@tonic-gate nbl_start_crit(vnode_t *vp, krw_t mode)
497c478bd9Sstevel@tonic-gate {
507c478bd9Sstevel@tonic-gate 	rw_enter(&vp->v_nbllock, mode);
517c478bd9Sstevel@tonic-gate }
527c478bd9Sstevel@tonic-gate 
537c478bd9Sstevel@tonic-gate /*
547c478bd9Sstevel@tonic-gate  * Leave the critical region.
557c478bd9Sstevel@tonic-gate  */
567c478bd9Sstevel@tonic-gate 
577c478bd9Sstevel@tonic-gate void
587c478bd9Sstevel@tonic-gate nbl_end_crit(vnode_t *vp)
597c478bd9Sstevel@tonic-gate {
607c478bd9Sstevel@tonic-gate 	rw_exit(&vp->v_nbllock);
617c478bd9Sstevel@tonic-gate }
627c478bd9Sstevel@tonic-gate 
637c478bd9Sstevel@tonic-gate /*
647c478bd9Sstevel@tonic-gate  * Return non-zero if some thread is in the critical region.
657c478bd9Sstevel@tonic-gate  * Note that this is appropriate for use in ASSERT()s only.
667c478bd9Sstevel@tonic-gate  */
677c478bd9Sstevel@tonic-gate 
687c478bd9Sstevel@tonic-gate int
697c478bd9Sstevel@tonic-gate nbl_in_crit(vnode_t *vp)
707c478bd9Sstevel@tonic-gate {
717c478bd9Sstevel@tonic-gate 	return (RW_LOCK_HELD(&vp->v_nbllock));
727c478bd9Sstevel@tonic-gate }
737c478bd9Sstevel@tonic-gate 
747c478bd9Sstevel@tonic-gate /*
757c478bd9Sstevel@tonic-gate  * Return the nbl_op_t that corresponds to the given lock type (read or
767c478bd9Sstevel@tonic-gate  * write).
777c478bd9Sstevel@tonic-gate  */
787c478bd9Sstevel@tonic-gate 
797c478bd9Sstevel@tonic-gate nbl_op_t
807c478bd9Sstevel@tonic-gate nbl_lock_to_op(int lock_type)
817c478bd9Sstevel@tonic-gate {
827c478bd9Sstevel@tonic-gate 	int level;
837c478bd9Sstevel@tonic-gate 
847c478bd9Sstevel@tonic-gate 	switch (lock_type) {
857c478bd9Sstevel@tonic-gate 	case F_WRLCK:
867c478bd9Sstevel@tonic-gate 		return (NBL_READWRITE);
877c478bd9Sstevel@tonic-gate 	case F_RDLCK:
887c478bd9Sstevel@tonic-gate 		return (NBL_READ);
897c478bd9Sstevel@tonic-gate 	default:
907c478bd9Sstevel@tonic-gate #ifdef DEBUG
917c478bd9Sstevel@tonic-gate 		level = CE_PANIC;
927c478bd9Sstevel@tonic-gate #else
937c478bd9Sstevel@tonic-gate 		level = CE_WARN;
947c478bd9Sstevel@tonic-gate #endif
957c478bd9Sstevel@tonic-gate 		cmn_err(level, "unexpected lock type: %d\n", lock_type);
967c478bd9Sstevel@tonic-gate 		return (NBL_WRITE);	/* pick something restrictive */
977c478bd9Sstevel@tonic-gate 	}
987c478bd9Sstevel@tonic-gate 	/*NOTREACHED*/
997c478bd9Sstevel@tonic-gate }
1007c478bd9Sstevel@tonic-gate 
1017c478bd9Sstevel@tonic-gate /*
1027c478bd9Sstevel@tonic-gate  * Returns non-zero if we need to look further for an NBMAND lock or
1037c478bd9Sstevel@tonic-gate  * share conflict.
1047c478bd9Sstevel@tonic-gate  */
1057c478bd9Sstevel@tonic-gate int
1067c478bd9Sstevel@tonic-gate nbl_need_check(vnode_t *vp)
1077c478bd9Sstevel@tonic-gate {
1087c478bd9Sstevel@tonic-gate 	/*
1097c478bd9Sstevel@tonic-gate 	 * Currently we only check if NBMAND locks/shares are allowed on
1107c478bd9Sstevel@tonic-gate 	 * the filesystem.  An option for the future would be to have a
1117c478bd9Sstevel@tonic-gate 	 * flag on the vnode, though the locking for that can get tricky.
1127c478bd9Sstevel@tonic-gate 	 */
1137c478bd9Sstevel@tonic-gate 	return ((vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND));
1147c478bd9Sstevel@tonic-gate }
1157c478bd9Sstevel@tonic-gate 
1167c478bd9Sstevel@tonic-gate /*
1177c478bd9Sstevel@tonic-gate  * Top-level conflict detection routine.  The arguments describe the
1187c478bd9Sstevel@tonic-gate  * operation that is being attempted.  If the operation conflicts with an
1197c478bd9Sstevel@tonic-gate  * existing lock or share reservation, a non-zero value is returned.  If
1207c478bd9Sstevel@tonic-gate  * the operation is allowed, zero is returned.  Note that there is an
1217c478bd9Sstevel@tonic-gate  * implicit argument, which is the process ID of the requester.
1227c478bd9Sstevel@tonic-gate  *
1237c478bd9Sstevel@tonic-gate  * svmand indicates that the file has System V mandatory locking enabled,
1247c478bd9Sstevel@tonic-gate  * so we should look at all record locks, not just NBMAND record locks.
1257c478bd9Sstevel@tonic-gate  * (This is to avoid a deadlock between a process making an I/O request and
1267c478bd9Sstevel@tonic-gate  * a process trying to release a lock.  Instead of letting the first
1277c478bd9Sstevel@tonic-gate  * process block in the filesystem code, we flag a conflict here.)
1287c478bd9Sstevel@tonic-gate  */
1297c478bd9Sstevel@tonic-gate 
1307c478bd9Sstevel@tonic-gate int
1317c478bd9Sstevel@tonic-gate nbl_conflict(vnode_t *vp,
1327c478bd9Sstevel@tonic-gate 		nbl_op_t op,		/* attempted operation */
1337c478bd9Sstevel@tonic-gate 		u_offset_t offset,	/* ignore if not I/O */
1347c478bd9Sstevel@tonic-gate 		ssize_t length,		/* ignore if not I/O */
135*da6c28aaSamw 		int svmand,		/* System V mandatory locking */
136*da6c28aaSamw 		caller_context_t *ct)	/* caller context */
1377c478bd9Sstevel@tonic-gate {
1387c478bd9Sstevel@tonic-gate 	ASSERT(nbl_in_crit(vp));
1397c478bd9Sstevel@tonic-gate 	ASSERT(op == NBL_READ || op == NBL_WRITE || op == NBL_RENAME ||
1407c478bd9Sstevel@tonic-gate 	    op == NBL_REMOVE || op == NBL_READWRITE);
1417c478bd9Sstevel@tonic-gate 
142*da6c28aaSamw 	if (nbl_share_conflict(vp, op, ct)) {
1437c478bd9Sstevel@tonic-gate 		return (1);
1447c478bd9Sstevel@tonic-gate 	}
1457c478bd9Sstevel@tonic-gate 
1467c478bd9Sstevel@tonic-gate 	/*
1477c478bd9Sstevel@tonic-gate 	 * If this is not an I/O request, there's no need to check against
1487c478bd9Sstevel@tonic-gate 	 * the locks on the file.
1497c478bd9Sstevel@tonic-gate 	 */
1507c478bd9Sstevel@tonic-gate 	if (op == NBL_REMOVE || op == NBL_RENAME)
1517c478bd9Sstevel@tonic-gate 		return (0);
1527c478bd9Sstevel@tonic-gate 
153*da6c28aaSamw 	return (nbl_lock_conflict(vp, op, offset, length, svmand, ct));
1547c478bd9Sstevel@tonic-gate }
1557c478bd9Sstevel@tonic-gate 
1567c478bd9Sstevel@tonic-gate /*
1577c478bd9Sstevel@tonic-gate  * Determine if the given file has mode bits for System V mandatory locks.
1587c478bd9Sstevel@tonic-gate  * If there was an error, the errno value is returned.  Otherwise, zero is
1597c478bd9Sstevel@tonic-gate  * returned and *svp is set appropriately (non-zero for mandatory locks,
1607c478bd9Sstevel@tonic-gate  * zero for no mandatory locks).
1617c478bd9Sstevel@tonic-gate  */
1627c478bd9Sstevel@tonic-gate 
1637c478bd9Sstevel@tonic-gate int
1647c478bd9Sstevel@tonic-gate nbl_svmand(vnode_t *vp, cred_t *cr, int *svp)
1657c478bd9Sstevel@tonic-gate {
1667c478bd9Sstevel@tonic-gate 	struct vattr va;
1677c478bd9Sstevel@tonic-gate 	int error;
1687c478bd9Sstevel@tonic-gate 
1697c478bd9Sstevel@tonic-gate 	va.va_mask = AT_MODE;
170*da6c28aaSamw 	error = VOP_GETATTR(vp, &va, 0, cr, NULL);
1717c478bd9Sstevel@tonic-gate 	if (error != 0)
1727c478bd9Sstevel@tonic-gate 		return (error);
1737c478bd9Sstevel@tonic-gate 
1747c478bd9Sstevel@tonic-gate 	*svp = MANDLOCK(vp, va.va_mode);
1757c478bd9Sstevel@tonic-gate 	return (0);
1767c478bd9Sstevel@tonic-gate }
177