xref: /openbmc/linux/fs/9p/vfs_dentry.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
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 
65 static 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);
70 	if (v9fs_fid_lookup(dentry)) {
71 		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 
96 void 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 
123 struct dentry_operations v9fs_dentry_operations = {
124 	.d_revalidate = v9fs_dentry_validate,
125 	.d_release = v9fs_dentry_release,
126 };
127