fs/xfs/xfs_behavior.c

   1 /*
   2  * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it would be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  11  *
  12  * Further, this software is distributed without any warranty that it is
  13  * free of the rightful claim of any third person regarding infringement
  14  * or the like.  Any license provided herein, whether implied or
  15  * otherwise, applies only to this software file.  Patent licenses, if
  16  * any, provided herein do not apply to combinations of this program with
  17  * other software, or any other product whatsoever.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write the Free Software Foundation, Inc., 59
  21  * Temple Place - Suite 330, Boston MA 02111-1307, USA.
  22  *
  23  * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
  24  * Mountain View, CA  94043, or:
  25  *
  26  * http://www.sgi.com
  27  *
  28  * For further information regarding this notice, see:
  29  *
  30  * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
  31  *
  32  */
  33 #include "xfs.h"
  34
  35 /*
  36  * Source file used to associate/disassociate behaviors with virtualized
  37  * objects.  See xfs_behavior.h for more information about behaviors, etc.
  38  *
  39  * The implementation is split between functions in this file and macros
  40  * in xfs_behavior.h.
  41  */
  42
  43 /*
  44  * Insert a new behavior descriptor into a behavior chain.
  45  *
  46  * The behavior chain is ordered based on the 'position' number which
  47  * lives in the first field of the ops vector (higher numbers first).
  48  *
  49  * Attemps to insert duplicate ops result in an EINVAL return code.
  50  * Otherwise, return 0 to indicate success.
  51  */
  52 int
  53 bhv_insert(bhv_head_t *bhp, bhv_desc_t *bdp)
  54 {
  55         bhv_desc_t      *curdesc, *prev;
  56         int             position;
  57
  58         /*
  59          * Validate the position value of the new behavior.
  60          */
  61         position = BHV_POSITION(bdp);
  62         ASSERT(position >= BHV_POSITION_BASE && position <= BHV_POSITION_TOP);
  63
  64         /*
  65          * Find location to insert behavior.  Check for duplicates.
  66          */
  67         prev = NULL;
  68         for (curdesc = bhp->bh_first;
  69              curdesc != NULL;
  70              curdesc = curdesc->bd_next) {
  71
  72                 /* Check for duplication. */
  73                 if (curdesc->bd_ops == bdp->bd_ops) {
  74                         ASSERT(0);
  75                         return EINVAL;
  76                 }
  77
  78                 /* Find correct position */
  79                 if (position >= BHV_POSITION(curdesc)) {
  80                         ASSERT(position != BHV_POSITION(curdesc));
  81                         break;          /* found it */
  82                 }
  83
  84                 prev = curdesc;
  85         }
  86
  87         if (prev == NULL) {
  88                 /* insert at front of chain */
  89                 bdp->bd_next = bhp->bh_first;
  90                 bhp->bh_first = bdp;
  91         } else {
  92                 /* insert after prev */
  93                 bdp->bd_next = prev->bd_next;
  94                 prev->bd_next = bdp;
  95         }
  96
  97         return 0;
  98 }
  99
 100 /*
 101  * Remove a behavior descriptor from a position in a behavior chain;
 102  * the postition is guaranteed not to be the first position.
 103  * Should only be called by the bhv_remove() macro.
 104  */
 105 void
 106 bhv_remove_not_first(bhv_head_t *bhp, bhv_desc_t *bdp)
 107 {
 108         bhv_desc_t      *curdesc, *prev;
 109
 110         ASSERT(bhp->bh_first != NULL);
 111         ASSERT(bhp->bh_first->bd_next != NULL);
 112
 113         prev = bhp->bh_first;
 114         for (curdesc = bhp->bh_first->bd_next;
 115              curdesc != NULL;
 116              curdesc = curdesc->bd_next) {
 117
 118                 if (curdesc == bdp)
 119                         break;          /* found it */
 120                 prev = curdesc;
 121         }
 122
 123         ASSERT(curdesc == bdp);
 124         prev->bd_next = bdp->bd_next;   /* remove from after prev */
 125 }
 126
 127 /*
 128  * Look for a specific ops vector on the specified behavior chain.
 129  * Return the associated behavior descriptor.  Or NULL, if not found.
 130  */
 131 bhv_desc_t *
 132 bhv_lookup(bhv_head_t *bhp, void *ops)
 133 {
 134         bhv_desc_t      *curdesc;
 135
 136         for (curdesc = bhp->bh_first;
 137              curdesc != NULL;
 138              curdesc = curdesc->bd_next) {
 139
 140                 if (curdesc->bd_ops == ops)
 141                         return curdesc;
 142         }
 143
 144         return NULL;
 145 }
 146
 147 /*
 148  * Looks for the first behavior within a specified range of positions.
 149  * Return the associated behavior descriptor.  Or NULL, if none found.
 150  */
 151 bhv_desc_t *
 152 bhv_lookup_range(bhv_head_t *bhp, int low, int high)
 153 {
 154         bhv_desc_t      *curdesc;
 155
 156         for (curdesc = bhp->bh_first;
 157              curdesc != NULL;
 158              curdesc = curdesc->bd_next) {
 159
 160                 int     position = BHV_POSITION(curdesc);
 161
 162                 if (position <= high) {
 163                         if (position >= low)
 164                                 return curdesc;
 165                         return NULL;
 166                 }
 167         }
 168
 169         return NULL;
 170 }
 171
 172 /*
 173  * Return the base behavior in the chain, or NULL if the chain
 174  * is empty.
 175  *
 176  * The caller has not read locked the behavior chain, so acquire the
 177  * lock before traversing the chain.
 178  */
 179 bhv_desc_t *
 180 bhv_base(bhv_head_t *bhp)
 181 {
 182         bhv_desc_t      *curdesc;
 183
 184         for (curdesc = bhp->bh_first;
 185              curdesc != NULL;
 186              curdesc = curdesc->bd_next) {
 187
 188                 if (curdesc->bd_next == NULL) {
 189                         return curdesc;
 190                 }
 191         }
 192
 193         return NULL;
 194 }
 195
 196 void
 197 bhv_head_init(
 198         bhv_head_t *bhp,
 199         char *name)
 200 {
 201         bhp->bh_first = NULL;
 202 }
 203
 204 void
 205 bhv_insert_initial(
 206         bhv_head_t *bhp,
 207         bhv_desc_t *bdp)
 208 {
 209         ASSERT(bhp->bh_first == NULL);
 210         (bhp)->bh_first = bdp;
 211 }
 212
 213 void
 214 bhv_head_destroy(
 215         bhv_head_t *bhp)
 216 {
 217         ASSERT(bhp->bh_first == NULL);
 218 }