FRV: Use generic show_interrupts()
[cris-mirror.git] / fs / 9p / fid.c
blob0ee594569dcceb60f4ff795f48fe83c87003fd47
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/slab.h>
28 #include <linux/sched.h>
29 #include <linux/idr.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_name.name);
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_name.name, 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 * We need to hold v9ses->rename_sem as long as we hold references
102 * to returned path array. Array element contain pointers to
103 * dentry names.
105 static int build_path_from_dentry(struct v9fs_session_info *v9ses,
106 struct dentry *dentry, char ***names)
108 int n = 0, i;
109 char **wnames;
110 struct dentry *ds;
112 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
113 n++;
115 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
116 if (!wnames)
117 goto err_out;
119 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
120 wnames[i] = (char *)ds->d_name.name;
122 *names = wnames;
123 return n;
124 err_out:
125 return -ENOMEM;
128 static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
129 uid_t uid, int any)
131 struct dentry *ds;
132 char **wnames, *uname;
133 int i, n, l, clone, access;
134 struct v9fs_session_info *v9ses;
135 struct p9_fid *fid, *old_fid = NULL;
137 v9ses = v9fs_dentry2v9ses(dentry);
138 access = v9ses->flags & V9FS_ACCESS_MASK;
139 fid = v9fs_fid_find(dentry, uid, any);
140 if (fid)
141 return fid;
143 * we don't have a matching fid. To do a TWALK we need
144 * parent fid. We need to prevent rename when we want to
145 * look at the parent.
147 down_read(&v9ses->rename_sem);
148 ds = dentry->d_parent;
149 fid = v9fs_fid_find(ds, uid, any);
150 if (fid) {
151 /* Found the parent fid do a lookup with that */
152 fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1);
153 goto fid_out;
155 up_read(&v9ses->rename_sem);
157 /* start from the root and try to do a lookup */
158 fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
159 if (!fid) {
160 /* the user is not attached to the fs yet */
161 if (access == V9FS_ACCESS_SINGLE)
162 return ERR_PTR(-EPERM);
164 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
165 uname = NULL;
166 else
167 uname = v9ses->uname;
169 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
170 v9ses->aname);
171 if (IS_ERR(fid))
172 return fid;
174 v9fs_fid_add(dentry->d_sb->s_root, fid);
176 /* If we are root ourself just return that */
177 if (dentry->d_sb->s_root == dentry)
178 return fid;
180 * Do a multipath walk with attached root.
181 * When walking parent we need to make sure we
182 * don't have a parallel rename happening
184 down_read(&v9ses->rename_sem);
185 n = build_path_from_dentry(v9ses, dentry, &wnames);
186 if (n < 0) {
187 fid = ERR_PTR(n);
188 goto err_out;
190 clone = 1;
191 i = 0;
192 while (i < n) {
193 l = min(n - i, P9_MAXWELEM);
195 * We need to hold rename lock when doing a multipath
196 * walk to ensure none of the patch component change
198 fid = p9_client_walk(fid, l, &wnames[i], clone);
199 if (IS_ERR(fid)) {
200 if (old_fid) {
202 * If we fail, clunk fid which are mapping
203 * to path component and not the last component
204 * of the path.
206 p9_client_clunk(old_fid);
208 kfree(wnames);
209 goto err_out;
211 old_fid = fid;
212 i += l;
213 clone = 0;
215 kfree(wnames);
216 fid_out:
217 if (!IS_ERR(fid))
218 v9fs_fid_add(dentry, fid);
219 err_out:
220 up_read(&v9ses->rename_sem);
221 return fid;
225 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
226 * @dentry: dentry to look for fid in
228 * Look for a fid in the specified dentry for the current user.
229 * If no fid is found, try to create one walking from a fid from the parent
230 * dentry (if it has one), or the root dentry. If the user haven't accessed
231 * the fs yet, attach now and walk from the root.
234 struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
236 uid_t uid;
237 int any, access;
238 struct v9fs_session_info *v9ses;
240 v9ses = v9fs_dentry2v9ses(dentry);
241 access = v9ses->flags & V9FS_ACCESS_MASK;
242 switch (access) {
243 case V9FS_ACCESS_SINGLE:
244 case V9FS_ACCESS_USER:
245 case V9FS_ACCESS_CLIENT:
246 uid = current_fsuid();
247 any = 0;
248 break;
250 case V9FS_ACCESS_ANY:
251 uid = v9ses->uid;
252 any = 1;
253 break;
255 default:
256 uid = ~0;
257 any = 0;
258 break;
260 return v9fs_fid_lookup_with_uid(dentry, uid, any);
263 struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
265 struct p9_fid *fid, *ret;
267 fid = v9fs_fid_lookup(dentry);
268 if (IS_ERR(fid))
269 return fid;
271 ret = p9_client_walk(fid, 0, NULL, 1);
272 return ret;
275 static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, uid_t uid)
277 struct p9_fid *fid, *ret;
279 fid = v9fs_fid_lookup_with_uid(dentry, uid, 0);
280 if (IS_ERR(fid))
281 return fid;
283 ret = p9_client_walk(fid, 0, NULL, 1);
284 return ret;
287 struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
289 int err, flags;
290 struct p9_fid *fid;
291 struct v9fs_session_info *v9ses;
293 v9ses = v9fs_dentry2v9ses(dentry);
294 fid = v9fs_fid_clone_with_uid(dentry, 0);
295 if (IS_ERR(fid))
296 goto error_out;
298 * writeback fid will only be used to write back the
299 * dirty pages. We always request for the open fid in read-write
300 * mode so that a partial page write which result in page
301 * read can work.
303 * we don't have a tsyncfs operation for older version
304 * of protocol. So make sure the write back fid is
305 * opened in O_SYNC mode.
307 if (!v9fs_proto_dotl(v9ses))
308 flags = O_RDWR | O_SYNC;
309 else
310 flags = O_RDWR;
312 err = p9_client_open(fid, flags);
313 if (err < 0) {
314 p9_client_clunk(fid);
315 fid = ERR_PTR(err);
316 goto error_out;
318 error_out:
319 return fid;