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Eric Van Hensbergene69e7fe2005-09-09 13:04:18 -07001/*
2 * linux/fs/9p/vfs_dentry.c
3 *
4 * This file contians vfs dentry ops for the 9P2000 protocol.
5 *
6 * Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
7 * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to:
21 * Free Software Foundation
22 * 51 Franklin Street, Fifth Floor
23 * Boston, MA 02111-1301 USA
24 *
25 */
26
27#include <linux/module.h>
28#include <linux/errno.h>
29#include <linux/fs.h>
30#include <linux/file.h>
31#include <linux/pagemap.h>
32#include <linux/stat.h>
33#include <linux/string.h>
34#include <linux/smp_lock.h>
35#include <linux/inet.h>
36#include <linux/namei.h>
37#include <linux/idr.h>
38
39#include "debug.h"
40#include "v9fs.h"
41#include "9p.h"
42#include "v9fs_vfs.h"
43#include "conv.h"
44#include "fid.h"
45
46/**
47 * v9fs_dentry_validate - VFS dcache hook to validate cache
48 * @dentry: dentry that is being validated
49 * @nd: path data
50 *
51 * dcache really shouldn't be used for 9P2000 as at all due to
52 * potential attached semantics to directory traversal (walk).
53 *
54 * FUTURE: look into how to use dcache to allow multi-stage
55 * walks in Plan 9 & potential for better dcache operation which
56 * would remain valid for Plan 9 semantics. Older versions
57 * had validation via stat for those interested. However, since
58 * stat has the same approximate overhead as walk there really
59 * is no difference. The only improvement would be from a
60 * time-decay cache like NFS has and that undermines the
61 * synchronous nature of 9P2000.
62 *
63 */
64
65static int v9fs_dentry_validate(struct dentry *dentry, struct nameidata *nd)
66{
67 struct dentry *dc = current->fs->pwd;
68
69 dprintk(DEBUG_VFS, "dentry: %s (%p)\n", dentry->d_iname, dentry);
Latchesar Ionkov0b8dd172005-09-27 21:45:24 -070070 if (v9fs_fid_lookup(dentry)) {
Eric Van Hensbergene69e7fe2005-09-09 13:04:18 -070071 dprintk(DEBUG_VFS, "VALID\n");
72 return 1;
73 }
74
75 while (dc != NULL) {
76 if (dc == dentry) {
77 dprintk(DEBUG_VFS, "VALID\n");
78 return 1;
79 }
80 if (dc == dc->d_parent)
81 break;
82
83 dc = dc->d_parent;
84 }
85
86 dprintk(DEBUG_VFS, "INVALID\n");
87 return 0;
88}
89
90/**
91 * v9fs_dentry_release - called when dentry is going to be freed
92 * @dentry: dentry that is being release
93 *
94 */
95
96void v9fs_dentry_release(struct dentry *dentry)
97{
98 dprintk(DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
99
100 if (dentry->d_fsdata != NULL) {
101 struct list_head *fid_list = dentry->d_fsdata;
102 struct v9fs_fid *temp = NULL;
103 struct v9fs_fid *current_fid = NULL;
104 struct v9fs_fcall *fcall = NULL;
105
106 list_for_each_entry_safe(current_fid, temp, fid_list, list) {
107 if (v9fs_t_clunk
108 (current_fid->v9ses, current_fid->fid, &fcall))
109 dprintk(DEBUG_ERROR, "clunk failed: %s\n",
110 FCALL_ERROR(fcall));
111
112 v9fs_put_idpool(current_fid->fid,
113 &current_fid->v9ses->fidpool);
114
115 kfree(fcall);
116 v9fs_fid_destroy(current_fid);
117 }
118
119 kfree(dentry->d_fsdata); /* free the list_head */
120 }
121}
122
123struct dentry_operations v9fs_dentry_operations = {
124 .d_revalidate = v9fs_dentry_validate,
125 .d_release = v9fs_dentry_release,
126};