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![Christoph Hellwig](/assets/img/avatar_default.png)
semantics. SGI-PV: 954580 SGI-Modid: xfs-linux-melb:xfs-kern:26563a Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Nathan Scott <nathans@sgi.com> Signed-off-by: Tim Shimmin <tes@sgi.com>
183 lines
4 KiB
C
183 lines
4 KiB
C
/*
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* Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "xfs.h"
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/*
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* Source file used to associate/disassociate behaviors with virtualized
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* objects. See xfs_behavior.h for more information about behaviors, etc.
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*
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* The implementation is split between functions in this file and macros
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* in xfs_behavior.h.
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*/
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/*
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* Insert a new behavior descriptor into a behavior chain.
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*
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* The behavior chain is ordered based on the 'position' number which
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* lives in the first field of the ops vector (higher numbers first).
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*
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* Attempts to insert duplicate ops result in an EINVAL return code.
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* Otherwise, return 0 to indicate success.
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*/
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int
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bhv_insert(bhv_head_t *bhp, bhv_desc_t *bdp)
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{
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bhv_desc_t *curdesc, *prev;
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int position;
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/*
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* Validate the position value of the new behavior.
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*/
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position = BHV_POSITION(bdp);
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ASSERT(position >= BHV_POSITION_BASE && position <= BHV_POSITION_TOP);
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/*
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* Find location to insert behavior. Check for duplicates.
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*/
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prev = NULL;
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for (curdesc = bhp->bh_first;
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curdesc != NULL;
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curdesc = curdesc->bd_next) {
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/* Check for duplication. */
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if (curdesc->bd_ops == bdp->bd_ops) {
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ASSERT(0);
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return EINVAL;
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}
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/* Find correct position */
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if (position >= BHV_POSITION(curdesc)) {
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ASSERT(position != BHV_POSITION(curdesc));
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break; /* found it */
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}
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prev = curdesc;
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}
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if (prev == NULL) {
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/* insert at front of chain */
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bdp->bd_next = bhp->bh_first;
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bhp->bh_first = bdp;
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} else {
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/* insert after prev */
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bdp->bd_next = prev->bd_next;
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prev->bd_next = bdp;
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}
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return 0;
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}
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/*
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* Remove a behavior descriptor from a position in a behavior chain;
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* the position is guaranteed not to be the first position.
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* Should only be called by the bhv_remove() macro.
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*/
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void
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bhv_remove_not_first(bhv_head_t *bhp, bhv_desc_t *bdp)
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{
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bhv_desc_t *curdesc, *prev;
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ASSERT(bhp->bh_first != NULL);
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ASSERT(bhp->bh_first->bd_next != NULL);
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prev = bhp->bh_first;
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for (curdesc = bhp->bh_first->bd_next;
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curdesc != NULL;
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curdesc = curdesc->bd_next) {
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if (curdesc == bdp)
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break; /* found it */
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prev = curdesc;
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}
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ASSERT(curdesc == bdp);
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prev->bd_next = bdp->bd_next; /* remove from after prev */
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}
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/*
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* Looks for the first behavior within a specified range of positions.
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* Return the associated behavior descriptor. Or NULL, if none found.
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*/
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bhv_desc_t *
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bhv_lookup_range(bhv_head_t *bhp, int low, int high)
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{
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bhv_desc_t *curdesc;
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for (curdesc = bhp->bh_first;
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curdesc != NULL;
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curdesc = curdesc->bd_next) {
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int position = BHV_POSITION(curdesc);
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if (position <= high) {
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if (position >= low)
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return curdesc;
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return NULL;
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}
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}
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return NULL;
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}
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/*
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* Return the base behavior in the chain, or NULL if the chain
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* is empty.
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*
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* The caller has not read locked the behavior chain, so acquire the
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* lock before traversing the chain.
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*/
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bhv_desc_t *
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bhv_base(bhv_head_t *bhp)
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{
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bhv_desc_t *curdesc;
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for (curdesc = bhp->bh_first;
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curdesc != NULL;
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curdesc = curdesc->bd_next) {
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if (curdesc->bd_next == NULL) {
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return curdesc;
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}
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}
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return NULL;
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}
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void
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bhv_head_init(
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bhv_head_t *bhp,
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char *name)
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{
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bhp->bh_first = NULL;
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}
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void
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bhv_insert_initial(
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bhv_head_t *bhp,
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bhv_desc_t *bdp)
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{
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ASSERT(bhp->bh_first == NULL);
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(bhp)->bh_first = bdp;
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}
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void
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bhv_head_destroy(
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bhv_head_t *bhp)
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{
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ASSERT(bhp->bh_first == NULL);
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}
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