fs/xfs/xfs_behavior.c

   1 /*
   2  * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include "xfs.h"
  19
  20 /*
  21  * Source file used to associate/disassociate behaviors with virtualized
  22  * objects.  See xfs_behavior.h for more information about behaviors, etc.
  23  *
  24  * The implementation is split between functions in this file and macros
  25  * in xfs_behavior.h.
  26  */
  27
  28 /*
  29  * Insert a new behavior descriptor into a behavior chain.
  30  *
  31  * The behavior chain is ordered based on the 'position' number which
  32  * lives in the first field of the ops vector (higher numbers first).
  33  *
  34  * Attempts to insert duplicate ops result in an EINVAL return code.
  35  * Otherwise, return 0 to indicate success.
  36  */
  37 int
  38 bhv_insert(bhv_head_t *bhp, bhv_desc_t *bdp)
  39 {
  40         bhv_desc_t      *curdesc, *prev;
  41         int             position;
  42
  43         /*
  44          * Validate the position value of the new behavior.
  45          */
  46         position = BHV_POSITION(bdp);
  47         ASSERT(position >= BHV_POSITION_BASE && position <= BHV_POSITION_TOP);
  48
  49         /*
  50          * Find location to insert behavior.  Check for duplicates.
  51          */
  52         prev = NULL;
  53         for (curdesc = bhp->bh_first;
  54              curdesc != NULL;
  55              curdesc = curdesc->bd_next) {
  56
  57                 /* Check for duplication. */
  58                 if (curdesc->bd_ops == bdp->bd_ops) {
  59                         ASSERT(0);
  60                         return EINVAL;
  61                 }
  62
  63                 /* Find correct position */
  64                 if (position >= BHV_POSITION(curdesc)) {
  65                         ASSERT(position != BHV_POSITION(curdesc));
  66                         break;          /* found it */
  67                 }
  68
  69                 prev = curdesc;
  70         }
  71
  72         if (prev == NULL) {
  73                 /* insert at front of chain */
  74                 bdp->bd_next = bhp->bh_first;
  75                 bhp->bh_first = bdp;
  76         } else {
  77                 /* insert after prev */
  78                 bdp->bd_next = prev->bd_next;
  79                 prev->bd_next = bdp;
  80         }
  81
  82         return 0;
  83 }
  84
  85 /*
  86  * Remove a behavior descriptor from a position in a behavior chain;
  87  * the position is guaranteed not to be the first position.
  88  * Should only be called by the bhv_remove() macro.
  89  */
  90 void
  91 bhv_remove_not_first(bhv_head_t *bhp, bhv_desc_t *bdp)
  92 {
  93         bhv_desc_t      *curdesc, *prev;
  94
  95         ASSERT(bhp->bh_first != NULL);
  96         ASSERT(bhp->bh_first->bd_next != NULL);
  97
  98         prev = bhp->bh_first;
  99         for (curdesc = bhp->bh_first->bd_next;
 100              curdesc != NULL;
 101              curdesc = curdesc->bd_next) {
 102
 103                 if (curdesc == bdp)
 104                         break;          /* found it */
 105                 prev = curdesc;
 106         }
 107
 108         ASSERT(curdesc == bdp);
 109         prev->bd_next = bdp->bd_next;   /* remove from after prev */
 110 }
 111
 112 /*
 113  * Look for a specific ops vector on the specified behavior chain.
 114  * Return the associated behavior descriptor.  Or NULL, if not found.
 115  */
 116 bhv_desc_t *
 117 bhv_lookup(bhv_head_t *bhp, void *ops)
 118 {
 119         bhv_desc_t      *curdesc;
 120
 121         for (curdesc = bhp->bh_first;
 122              curdesc != NULL;
 123              curdesc = curdesc->bd_next) {
 124
 125                 if (curdesc->bd_ops == ops)
 126                         return curdesc;
 127         }
 128
 129         return NULL;
 130 }
 131
 132 /*
 133  * Looks for the first behavior within a specified range of positions.
 134  * Return the associated behavior descriptor.  Or NULL, if none found.
 135  */
 136 bhv_desc_t *
 137 bhv_lookup_range(bhv_head_t *bhp, int low, int high)
 138 {
 139         bhv_desc_t      *curdesc;
 140
 141         for (curdesc = bhp->bh_first;
 142              curdesc != NULL;
 143              curdesc = curdesc->bd_next) {
 144
 145                 int     position = BHV_POSITION(curdesc);
 146
 147                 if (position <= high) {
 148                         if (position >= low)
 149                                 return curdesc;
 150                         return NULL;
 151                 }
 152         }
 153
 154         return NULL;
 155 }
 156
 157 /*
 158  * Return the base behavior in the chain, or NULL if the chain
 159  * is empty.
 160  *
 161  * The caller has not read locked the behavior chain, so acquire the
 162  * lock before traversing the chain.
 163  */
 164 bhv_desc_t *
 165 bhv_base(bhv_head_t *bhp)
 166 {
 167         bhv_desc_t      *curdesc;
 168
 169         for (curdesc = bhp->bh_first;
 170              curdesc != NULL;
 171              curdesc = curdesc->bd_next) {
 172
 173                 if (curdesc->bd_next == NULL) {
 174                         return curdesc;
 175                 }
 176         }
 177
 178         return NULL;
 179 }
 180
 181 void
 182 bhv_head_init(
 183         bhv_head_t *bhp,
 184         char *name)
 185 {
 186         bhp->bh_first = NULL;
 187 }
 188
 189 void
 190 bhv_insert_initial(
 191         bhv_head_t *bhp,
 192         bhv_desc_t *bdp)
 193 {
 194         ASSERT(bhp->bh_first == NULL);
 195         (bhp)->bh_first = bdp;
 196 }
 197
 198 void
 199 bhv_head_destroy(
 200         bhv_head_t *bhp)
 201 {
 202         ASSERT(bhp->bh_first == NULL);
 203 }