forked from Minki/linux
531b1094b7
Performance enhancement reducing the number of copies in the data and stat paths. Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Cc: Eric Van Hensbergen <ericvh@ericvh.myip.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
253 lines
5.9 KiB
C
253 lines
5.9 KiB
C
/*
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* V9FS FID Management
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*
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* Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will 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 to:
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* Free Software Foundation
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* 51 Franklin Street, Fifth Floor
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* Boston, MA 02111-1301 USA
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*
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/idr.h>
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#include "debug.h"
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#include "v9fs.h"
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#include "9p.h"
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#include "v9fs_vfs.h"
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#include "fid.h"
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/**
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* v9fs_fid_insert - add a fid to a dentry
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* @fid: fid to add
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* @dentry: dentry that it is being added to
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*
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*/
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static int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry)
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{
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struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
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dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid,
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dentry->d_iname, dentry);
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if (dentry->d_fsdata == NULL) {
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dentry->d_fsdata =
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kmalloc(sizeof(struct list_head), GFP_KERNEL);
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if (dentry->d_fsdata == NULL) {
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dprintk(DEBUG_ERROR, "Out of memory\n");
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return -ENOMEM;
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}
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fid_list = (struct list_head *)dentry->d_fsdata;
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INIT_LIST_HEAD(fid_list); /* Initialize list head */
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}
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fid->uid = current->uid;
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fid->pid = current->pid;
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list_add(&fid->list, fid_list);
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return 0;
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}
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/**
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* v9fs_fid_create - allocate a FID structure
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* @dentry - dentry to link newly created fid to
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*
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*/
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struct v9fs_fid *v9fs_fid_create(struct dentry *dentry,
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struct v9fs_session_info *v9ses, int fid, int create)
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{
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struct v9fs_fid *new;
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dprintk(DEBUG_9P, "fid create dentry %p, fid %d, create %d\n",
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dentry, fid, create);
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new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
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if (new == NULL) {
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dprintk(DEBUG_ERROR, "Out of Memory\n");
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return ERR_PTR(-ENOMEM);
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}
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new->fid = fid;
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new->v9ses = v9ses;
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new->fidopen = 0;
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new->fidcreate = create;
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new->fidclunked = 0;
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new->iounit = 0;
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new->rdir_pos = 0;
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new->rdir_fcall = NULL;
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if (v9fs_fid_insert(new, dentry) == 0)
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return new;
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else {
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dprintk(DEBUG_ERROR, "Problems inserting to dentry\n");
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kfree(new);
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return NULL;
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}
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}
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/**
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* v9fs_fid_destroy - deallocate a FID structure
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* @fid: fid to destroy
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*
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*/
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void v9fs_fid_destroy(struct v9fs_fid *fid)
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{
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list_del(&fid->list);
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kfree(fid);
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}
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/**
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* v9fs_fid_walk_up - walks from the process current directory
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* up to the specified dentry.
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*/
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static struct v9fs_fid *v9fs_fid_walk_up(struct dentry *dentry)
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{
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int fidnum, cfidnum, err;
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struct v9fs_fid *cfid;
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struct dentry *cde;
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struct v9fs_session_info *v9ses;
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v9ses = v9fs_inode2v9ses(current->fs->pwd->d_inode);
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cfid = v9fs_fid_lookup(current->fs->pwd);
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if (cfid == NULL) {
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dprintk(DEBUG_ERROR, "process cwd doesn't have a fid\n");
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return ERR_PTR(-ENOENT);
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}
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cfidnum = cfid->fid;
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cde = current->fs->pwd;
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/* TODO: take advantage of multiwalk */
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fidnum = v9fs_get_idpool(&v9ses->fidpool);
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if (fidnum < 0) {
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dprintk(DEBUG_ERROR, "could not get a new fid num\n");
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err = -ENOENT;
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goto clunk_fid;
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}
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while (cde != dentry) {
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if (cde == cde->d_parent) {
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dprintk(DEBUG_ERROR, "can't find dentry\n");
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err = -ENOENT;
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goto clunk_fid;
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}
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err = v9fs_t_walk(v9ses, cfidnum, fidnum, "..", NULL);
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if (err < 0) {
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dprintk(DEBUG_ERROR, "problem walking to parent\n");
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goto clunk_fid;
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}
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cfidnum = fidnum;
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cde = cde->d_parent;
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}
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return v9fs_fid_create(dentry, v9ses, fidnum, 0);
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clunk_fid:
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v9fs_t_clunk(v9ses, fidnum);
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return ERR_PTR(err);
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}
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/**
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* v9fs_fid_lookup - retrieve the right fid from a particular dentry
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* @dentry: dentry to look for fid in
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* @type: intent of lookup (operation or traversal)
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*
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* search list of fids associated with a dentry for a fid with a matching
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* thread id or uid. If that fails, look up the dentry's parents to see if you
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* can find a matching fid.
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*
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*/
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struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
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{
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struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
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struct v9fs_fid *current_fid = NULL;
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struct v9fs_fid *temp = NULL;
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struct v9fs_fid *return_fid = NULL;
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dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
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if (fid_list) {
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list_for_each_entry_safe(current_fid, temp, fid_list, list) {
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if (!current_fid->fidcreate) {
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return_fid = current_fid;
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break;
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}
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}
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if (!return_fid)
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return_fid = current_fid;
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}
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/* we are at the root but didn't match */
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if ((!return_fid) && (dentry->d_parent == dentry)) {
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/* TODO: clone attach with new uid */
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return_fid = current_fid;
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}
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if (!return_fid) {
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struct dentry *par = current->fs->pwd->d_parent;
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int count = 1;
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while (par != NULL) {
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if (par == dentry)
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break;
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count++;
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if (par == par->d_parent) {
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dprintk(DEBUG_ERROR,
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"got to root without finding dentry\n");
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break;
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}
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par = par->d_parent;
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}
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/* XXX - there may be some duplication we can get rid of */
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if (par == dentry) {
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return_fid = v9fs_fid_walk_up(dentry);
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if (IS_ERR(return_fid))
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return_fid = NULL;
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}
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}
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return return_fid;
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}
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struct v9fs_fid *v9fs_fid_get_created(struct dentry *dentry)
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{
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struct list_head *fid_list;
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struct v9fs_fid *fid, *ftmp, *ret;
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dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
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fid_list = (struct list_head *)dentry->d_fsdata;
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ret = NULL;
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if (fid_list) {
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list_for_each_entry_safe(fid, ftmp, fid_list, list) {
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if (fid->fidcreate && fid->pid == current->pid) {
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list_del(&fid->list);
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ret = fid;
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break;
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}
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}
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}
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dprintk(DEBUG_9P, "return %p\n", ret);
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return ret;
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}
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