1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  *
  25  * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
  26  */
  27 
  28 /*
  29  * Utility routines and top-level conflict detection code for NBMAND
  30  * locks.
  31  */
  32 
  33 #include <sys/nbmlock.h>
  34 #include <sys/rwlock.h>
  35 #include <sys/vnode.h>
  36 #include <sys/cmn_err.h>
  37 #include <sys/debug.h>
  38 #include <sys/types.h>
  39 #include <sys/fcntl.h>
  40 #include <sys/vfs.h>
  41 
  42 /*
  43  * Enter the critical region for synchronizing I/O requests with lock/share
  44  * requests.  "mode" specifies whether the caller intends to update
  45  * lock/share state (as opposed to just query it).
  46  */
  47 
  48 void
  49 nbl_start_crit(vnode_t *vp, krw_t mode)
  50 {
  51         rw_enter(&vp->v_nbllock, mode);
  52 }
  53 
  54 /*
  55  * Leave the critical region.
  56  */
  57 
  58 void
  59 nbl_end_crit(vnode_t *vp)
  60 {
  61         rw_exit(&vp->v_nbllock);
  62 }
  63 
  64 /*
  65  * Return non-zero if some thread is in the critical region.
  66  * Note that this is appropriate for use in ASSERT()s only.
  67  */
  68 
  69 int
  70 nbl_in_crit(vnode_t *vp)
  71 {
  72         return (RW_LOCK_HELD(&vp->v_nbllock));
  73 }
  74 
  75 /*
  76  * Returns non-zero if we need to look further for an NBMAND lock or
  77  * share conflict.
  78  */
  79 int
  80 nbl_need_check(vnode_t *vp)
  81 {
  82         /*
  83          * Currently we only check if NBMAND locks/shares are allowed on
  84          * the filesystem.  An option for the future would be to have a
  85          * flag on the vnode, though the locking for that can get tricky.
  86          */
  87         return ((vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND));
  88 }
  89 
  90 /* No locks, so no conflicts. */
  91 int
  92 nbl_conflict(vnode_t *vp,
  93         nbl_op_t op,            /* attempted operation */
  94         u_offset_t offset,      /* ignore if not I/O */
  95         ssize_t length,         /* ignore if not I/O */
  96         int svmand,             /* System V mandatory locking */
  97         caller_context_t *ct)   /* caller context */
  98 {
  99         ASSERT(nbl_in_crit(vp));
 100 
 101         return (0);
 102 }
 103 
 104 /*
 105  * Determine if the given file has mode bits for System V mandatory locks.
 106  * If there was an error, the errno value is returned.  Otherwise, zero is
 107  * returned and *svp is set appropriately (non-zero for mandatory locks,
 108  * zero for no mandatory locks).
 109  */
 110 
 111 int
 112 nbl_svmand(vnode_t *vp, cred_t *cr, int *svp)
 113 {
 114         struct vattr va;
 115         int error;
 116 
 117         va.va_mask = AT_MODE;
 118         error = VOP_GETATTR(vp, &va, 0, cr, NULL);
 119         if (error != 0)
 120                 return (error);
 121 
 122         *svp = MANDLOCK(vp, va.va_mode);
 123         return (0);
 124 }