Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
[wrt350n-kernel.git] / fs / 9p / fid.c
blobdfebdbe7440e6f31f627fdd41718cf55c459a55d
1 /*
2 * V9FS FID Management
4 * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
5 * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2
9 * as published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to:
18 * Free Software Foundation
19 * 51 Franklin Street, Fifth Floor
20 * Boston, MA 02111-1301 USA
24 #include <linux/module.h>
25 #include <linux/errno.h>
26 #include <linux/fs.h>
27 #include <linux/sched.h>
28 #include <linux/idr.h>
29 #include <asm/semaphore.h>
30 #include <net/9p/9p.h>
31 #include <net/9p/client.h>
33 #include "v9fs.h"
34 #include "v9fs_vfs.h"
35 #include "fid.h"
37 /**
38 * v9fs_fid_add - add a fid to a dentry
39 * @dentry: dentry that the fid is being added to
40 * @fid: fid to add
44 int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
46 struct v9fs_dentry *dent;
48 P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
49 fid->fid, dentry->d_iname);
51 dent = dentry->d_fsdata;
52 if (!dent) {
53 dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
54 if (!dent)
55 return -ENOMEM;
57 spin_lock_init(&dent->lock);
58 INIT_LIST_HEAD(&dent->fidlist);
59 dentry->d_fsdata = dent;
62 spin_lock(&dent->lock);
63 list_add(&fid->dlist, &dent->fidlist);
64 spin_unlock(&dent->lock);
66 return 0;
69 /**
70 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
71 * @dentry: dentry to look for fid in
72 * @uid: return fid that belongs to the specified user
73 * @any: if non-zero, return any fid associated with the dentry
77 static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any)
79 struct v9fs_dentry *dent;
80 struct p9_fid *fid, *ret;
82 P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
83 dentry->d_iname, dentry, uid, any);
84 dent = (struct v9fs_dentry *) dentry->d_fsdata;
85 ret = NULL;
86 if (dent) {
87 spin_lock(&dent->lock);
88 list_for_each_entry(fid, &dent->fidlist, dlist) {
89 if (any || fid->uid == uid) {
90 ret = fid;
91 break;
94 spin_unlock(&dent->lock);
97 return ret;
101 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
102 * @dentry: dentry to look for fid in
104 * Look for a fid in the specified dentry for the current user.
105 * If no fid is found, try to create one walking from a fid from the parent
106 * dentry (if it has one), or the root dentry. If the user haven't accessed
107 * the fs yet, attach now and walk from the root.
110 struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
112 int i, n, l, clone, any, access;
113 u32 uid;
114 struct p9_fid *fid;
115 struct dentry *d, *ds;
116 struct v9fs_session_info *v9ses;
117 char **wnames, *uname;
119 v9ses = v9fs_inode2v9ses(dentry->d_inode);
120 access = v9ses->flags & V9FS_ACCESS_MASK;
121 switch (access) {
122 case V9FS_ACCESS_SINGLE:
123 case V9FS_ACCESS_USER:
124 uid = current->fsuid;
125 any = 0;
126 break;
128 case V9FS_ACCESS_ANY:
129 uid = v9ses->uid;
130 any = 1;
131 break;
133 default:
134 uid = ~0;
135 any = 0;
136 break;
139 fid = v9fs_fid_find(dentry, uid, any);
140 if (fid)
141 return fid;
143 ds = dentry->d_parent;
144 fid = v9fs_fid_find(ds, uid, any);
145 if (!fid) { /* walk from the root */
146 n = 0;
147 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
148 n++;
150 fid = v9fs_fid_find(ds, uid, any);
151 if (!fid) { /* the user is not attached to the fs yet */
152 if (access == V9FS_ACCESS_SINGLE)
153 return ERR_PTR(-EPERM);
155 if (v9fs_extended(v9ses))
156 uname = NULL;
157 else
158 uname = v9ses->uname;
160 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
161 v9ses->aname);
163 if (IS_ERR(fid))
164 return fid;
166 v9fs_fid_add(ds, fid);
168 } else /* walk from the parent */
169 n = 1;
171 if (ds == dentry)
172 return fid;
174 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
175 if (!wnames)
176 return ERR_PTR(-ENOMEM);
178 for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent)
179 wnames[i] = (char *) d->d_name.name;
181 clone = 1;
182 i = 0;
183 while (i < n) {
184 l = min(n - i, P9_MAXWELEM);
185 fid = p9_client_walk(fid, l, &wnames[i], clone);
186 if (IS_ERR(fid)) {
187 kfree(wnames);
188 return fid;
191 i += l;
192 clone = 0;
195 kfree(wnames);
196 v9fs_fid_add(dentry, fid);
197 return fid;
200 struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
202 struct p9_fid *fid, *ret;
204 fid = v9fs_fid_lookup(dentry);
205 if (IS_ERR(fid))
206 return fid;
208 ret = p9_client_walk(fid, 0, NULL, 1);
209 return ret;