usr/src/lib/smbsrv/libfksmbsrv/common/fake_nblk.c

   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 2013 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/types.h>
  34 #include <sys/cmn_err.h>
  35 #include <sys/debug.h>
  36 #include <sys/fcntl.h>
  37 #include <sys/rwlock.h>
  38 #include <sys/vnode.h>
  39 #include <sys/vfs.h>
  40 #include <sys/nbmlock.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 /* ARGSUSED */
  80 int
  81 nbl_need_check(vnode_t *vp)
  82 {
  83         /*
  84          * Currently we only check if NBMAND locks/shares are allowed on
  85          * the filesystem.  An option for the future would be to have a
  86          * flag on the vnode, though the locking for that can get tricky.
  87          */
  88         /* (vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND)) */
  89         return (0);
  90 }
  91
  92 /*
  93  * Top-level conflict detection routine.  The arguments describe the
  94  * operation that is being attempted.  If the operation conflicts with an
  95  * existing lock or share reservation, a non-zero value is returned.  If
  96  * the operation is allowed, zero is returned.  Note that there is an
  97  * implicit argument, which is the process ID of the requester.
  98  *
  99  * svmand indicates that the file has System V mandatory locking enabled,
 100  * so we should look at all record locks, not just NBMAND record locks.
 101  * (This is to avoid a deadlock between a process making an I/O request and
 102  * a process trying to release a lock.  Instead of letting the first
 103  * process block in the filesystem code, we flag a conflict here.)
 104  */
 105
 106 int
 107 nbl_conflict(vnode_t *vp,
 108                 nbl_op_t op,            /* attempted operation */
 109                 u_offset_t offset,      /* ignore if not I/O */
 110                 ssize_t length,         /* ignore if not I/O */
 111                 int svmand,             /* System V mandatory locking */
 112                 caller_context_t *ct)   /* caller context */
 113 {
 114         ASSERT(nbl_in_crit(vp));
 115         ASSERT(op == NBL_READ || op == NBL_WRITE || op == NBL_RENAME ||
 116             op == NBL_REMOVE || op == NBL_READWRITE);
 117
 118         if (nbl_share_conflict(vp, op, ct)) {
 119                 return (1);
 120         }
 121
 122         /*
 123          * If this is not an I/O request, there's no need to check against
 124          * the locks on the file.
 125          */
 126         if (op == NBL_REMOVE || op == NBL_RENAME)
 127                 return (0);
 128
 129         return (nbl_lock_conflict(vp, op, offset, length, svmand, ct));
 130 }
 131
 132 /*
 133  * Determine if the given file has mode bits for System V mandatory locks.
 134  * If there was an error, the errno value is returned.  Otherwise, zero is
 135  * returned and *svp is set appropriately (non-zero for mandatory locks,
 136  * zero for no mandatory locks).
 137  */
 138
 139 int
 140 nbl_svmand(vnode_t *vp, cred_t *cr, int *svp)
 141 {
 142         struct vattr va;
 143         int error;
 144
 145         va.va_mask = AT_MODE;
 146         error = VOP_GETATTR(vp, &va, 0, cr, NULL);
 147         if (error != 0)
 148                 return (error);
 149
 150         *svp = MANDLOCK(vp, va.va_mode);
 151         return (0);
 152 }
 153
 154 /*
 155  * The kernel handles this for us when we actually try I/O.
 156  */
 157 /* ARGSUSED */
 158 int
 159 nbl_share_conflict(vnode_t *vp, nbl_op_t op, caller_context_t *ct)
 160 {
 161         return (0);
 162 }
 163
 164 /*
 165  * The kernel handles this for us when we actually try I/O.
 166  */
 167 /* ARGSUSED */
 168 int
 169 nbl_lock_conflict(vnode_t *vp, nbl_op_t op, u_offset_t offset,
 170                 ssize_t length, int svmand, caller_context_t *ct)
 171 {
 172         return (0);
 173 }