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1da177e4 1/*
08e0e7c8 2 * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
1da177e4
LT
3 *
4 * This software may be freely redistributed under the terms of the
5 * GNU General Public License.
6 *
7 * You should have received a copy of the GNU General Public License
8 * along with this program; if not, write to the Free Software
9 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
10 *
44d1b980 11 * Authors: David Woodhouse <dwmw2@infradead.org>
1da177e4
LT
12 * David Howells <dhowells@redhat.com>
13 *
14 */
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/init.h>
08e0e7c8 19#include <linux/circ_buf.h>
e8edc6e0 20#include <linux/sched.h>
1da177e4 21#include "internal.h"
08e0e7c8 22
47ea0f2e
DH
23/*
24 * Create volume and callback interests on a server.
25 */
26static struct afs_cb_interest *afs_create_interest(struct afs_server *server,
27 struct afs_vnode *vnode)
28{
29 struct afs_vol_interest *new_vi, *vi;
30 struct afs_cb_interest *new;
31 struct hlist_node **pp;
32
33 new_vi = kzalloc(sizeof(struct afs_vol_interest), GFP_KERNEL);
34 if (!new_vi)
35 return NULL;
36
37 new = kzalloc(sizeof(struct afs_cb_interest), GFP_KERNEL);
38 if (!new) {
39 kfree(new_vi);
40 return NULL;
41 }
42
43 new_vi->usage = 1;
44 new_vi->vid = vnode->volume->vid;
45 INIT_HLIST_NODE(&new_vi->srv_link);
46 INIT_HLIST_HEAD(&new_vi->cb_interests);
47
48 refcount_set(&new->usage, 1);
49 new->sb = vnode->vfs_inode.i_sb;
50 new->vid = vnode->volume->vid;
45218193 51 new->server = afs_get_server(server, afs_server_trace_get_new_cbi);
47ea0f2e
DH
52 INIT_HLIST_NODE(&new->cb_vlink);
53
54 write_lock(&server->cb_break_lock);
55
56 for (pp = &server->cb_volumes.first; *pp; pp = &(*pp)->next) {
57 vi = hlist_entry(*pp, struct afs_vol_interest, srv_link);
58 if (vi->vid < new_vi->vid)
59 continue;
60 if (vi->vid > new_vi->vid)
61 break;
62 vi->usage++;
63 goto found_vi;
64 }
65
66 new_vi->srv_link.pprev = pp;
67 new_vi->srv_link.next = *pp;
68 if (*pp)
69 (*pp)->pprev = &new_vi->srv_link.next;
70 *pp = &new_vi->srv_link;
71 vi = new_vi;
72 new_vi = NULL;
73found_vi:
74
75 new->vol_interest = vi;
76 hlist_add_head(&new->cb_vlink, &vi->cb_interests);
77
78 write_unlock(&server->cb_break_lock);
79 kfree(new_vi);
80 return new;
81}
82
1da177e4 83/*
c435ee34
DH
84 * Set up an interest-in-callbacks record for a volume on a server and
85 * register it with the server.
d4a96bec 86 * - Called with vnode->io_lock held.
1da177e4 87 */
c435ee34 88int afs_register_server_cb_interest(struct afs_vnode *vnode,
d4a96bec
DH
89 struct afs_server_list *slist,
90 unsigned int index)
1da177e4 91{
d4a96bec
DH
92 struct afs_server_entry *entry = &slist->servers[index];
93 struct afs_cb_interest *cbi, *vcbi, *new, *old;
d2ddc776 94 struct afs_server *server = entry->server;
c435ee34
DH
95
96again:
f642404a
DH
97 vcbi = rcu_dereference_protected(vnode->cb_interest,
98 lockdep_is_held(&vnode->io_lock));
99 if (vcbi && likely(vcbi == entry->cb_interest))
d4a96bec
DH
100 return 0;
101
102 read_lock(&slist->lock);
103 cbi = afs_get_cb_interest(entry->cb_interest);
104 read_unlock(&slist->lock);
105
c435ee34 106 if (vcbi) {
d4a96bec
DH
107 if (vcbi == cbi) {
108 afs_put_cb_interest(afs_v2net(vnode), cbi);
c435ee34 109 return 0;
d4a96bec 110 }
c435ee34 111
d4a96bec
DH
112 /* Use a new interest in the server list for the same server
113 * rather than an old one that's still attached to a vnode.
114 */
c435ee34
DH
115 if (cbi && vcbi->server == cbi->server) {
116 write_seqlock(&vnode->cb_lock);
f642404a
DH
117 old = rcu_dereference_protected(vnode->cb_interest,
118 lockdep_is_held(&vnode->cb_lock.lock));
119 rcu_assign_pointer(vnode->cb_interest, cbi);
c435ee34 120 write_sequnlock(&vnode->cb_lock);
d4a96bec 121 afs_put_cb_interest(afs_v2net(vnode), old);
c435ee34
DH
122 return 0;
123 }
1da177e4 124
d4a96bec 125 /* Re-use the one attached to the vnode. */
c435ee34 126 if (!cbi && vcbi->server == server) {
d4a96bec
DH
127 write_lock(&slist->lock);
128 if (entry->cb_interest) {
129 write_unlock(&slist->lock);
130 afs_put_cb_interest(afs_v2net(vnode), cbi);
c435ee34
DH
131 goto again;
132 }
d4a96bec
DH
133
134 entry->cb_interest = cbi;
135 write_unlock(&slist->lock);
c435ee34
DH
136 return 0;
137 }
138 }
1da177e4 139
c435ee34 140 if (!cbi) {
47ea0f2e 141 new = afs_create_interest(server, vnode);
c435ee34
DH
142 if (!new)
143 return -ENOMEM;
144
d4a96bec
DH
145 write_lock(&slist->lock);
146 if (!entry->cb_interest) {
147 entry->cb_interest = afs_get_cb_interest(new);
c435ee34 148 cbi = new;
d4a96bec 149 new = NULL;
c435ee34 150 } else {
d4a96bec 151 cbi = afs_get_cb_interest(entry->cb_interest);
c435ee34 152 }
d4a96bec
DH
153 write_unlock(&slist->lock);
154 afs_put_cb_interest(afs_v2net(vnode), new);
08e0e7c8 155 }
1da177e4 156
c435ee34
DH
157 ASSERT(cbi);
158
159 /* Change the server the vnode is using. This entails scrubbing any
160 * interest the vnode had in the previous server it was using.
161 */
162 write_seqlock(&vnode->cb_lock);
163
f642404a
DH
164 old = rcu_dereference_protected(vnode->cb_interest,
165 lockdep_is_held(&vnode->cb_lock.lock));
166 rcu_assign_pointer(vnode->cb_interest, cbi);
c435ee34 167 vnode->cb_s_break = cbi->server->cb_s_break;
68251f0a 168 vnode->cb_v_break = vnode->volume->cb_v_break;
c435ee34
DH
169 clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
170
171 write_sequnlock(&vnode->cb_lock);
d4a96bec 172 afs_put_cb_interest(afs_v2net(vnode), old);
c435ee34 173 return 0;
08e0e7c8 174}
1da177e4 175
c435ee34
DH
176/*
177 * Remove an interest on a server.
178 */
179void afs_put_cb_interest(struct afs_net *net, struct afs_cb_interest *cbi)
180{
47ea0f2e
DH
181 struct afs_vol_interest *vi;
182
c435ee34 183 if (cbi && refcount_dec_and_test(&cbi->usage)) {
47ea0f2e 184 if (!hlist_unhashed(&cbi->cb_vlink)) {
c435ee34 185 write_lock(&cbi->server->cb_break_lock);
47ea0f2e
DH
186
187 hlist_del_init(&cbi->cb_vlink);
188 vi = cbi->vol_interest;
189 cbi->vol_interest = NULL;
190 if (--vi->usage == 0)
191 hlist_del(&vi->srv_link);
192 else
193 vi = NULL;
194
c435ee34 195 write_unlock(&cbi->server->cb_break_lock);
f642404a
DH
196 if (vi)
197 kfree_rcu(vi, rcu);
45218193 198 afs_put_server(net, cbi->server, afs_server_trace_put_cbi);
c435ee34 199 }
f642404a 200 kfree_rcu(cbi, rcu);
08e0e7c8 201 }
c435ee34
DH
202}
203
204/*
205 * allow the fileserver to request callback state (re-)initialisation
206 */
207void afs_init_callback_state(struct afs_server *server)
208{
eeba1e9c 209 server->cb_s_break++;
08e0e7c8
DH
210}
211
212/*
213 * actually break a callback
214 */
051d2525 215void __afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
08e0e7c8
DH
216{
217 _enter("");
218
5a813276 219 clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
c435ee34
DH
220 if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
221 vnode->cb_break++;
222 afs_clear_permits(vnode);
08e0e7c8 223
c7226e40 224 if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
e8d6c554 225 afs_lock_may_be_available(vnode);
051d2525
DH
226
227 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, true);
228 } else {
229 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, false);
08e0e7c8 230 }
30062bd1 231}
c435ee34 232
051d2525 233void afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
30062bd1
DH
234{
235 write_seqlock(&vnode->cb_lock);
051d2525 236 __afs_break_callback(vnode, reason);
c435ee34 237 write_sequnlock(&vnode->cb_lock);
08e0e7c8
DH
238}
239
240/*
241 * allow the fileserver to explicitly break one callback
242 * - happens when
243 * - the backing file is changed
244 * - a lock is released
245 */
246static void afs_break_one_callback(struct afs_server *server,
247 struct afs_fid *fid)
248{
47ea0f2e 249 struct afs_vol_interest *vi;
c435ee34
DH
250 struct afs_cb_interest *cbi;
251 struct afs_iget_data data;
08e0e7c8 252 struct afs_vnode *vnode;
c435ee34 253 struct inode *inode;
08e0e7c8 254
c435ee34 255 read_lock(&server->cb_break_lock);
47ea0f2e
DH
256 hlist_for_each_entry(vi, &server->cb_volumes, srv_link) {
257 if (vi->vid < fid->vid)
258 continue;
259 if (vi->vid > fid->vid) {
260 vi = NULL;
261 break;
262 }
263 //atomic_inc(&vi->usage);
264 break;
265 }
266
267 /* TODO: Find all matching volumes if we couldn't match the server and
268 * break them anyway.
269 */
270 if (!vi)
271 goto out;
08e0e7c8 272
c435ee34
DH
273 /* Step through all interested superblocks. There may be more than one
274 * because of cell aliasing.
275 */
47ea0f2e 276 hlist_for_each_entry(cbi, &vi->cb_interests, cb_vlink) {
68251f0a
DH
277 if (fid->vnode == 0 && fid->unique == 0) {
278 /* The callback break applies to an entire volume. */
279 struct afs_super_info *as = AFS_FS_S(cbi->sb);
280 struct afs_volume *volume = as->volume;
281
90fa9b64 282 write_lock(&volume->cb_v_break_lock);
68251f0a 283 volume->cb_v_break++;
051d2525
DH
284 trace_afs_cb_break(fid, volume->cb_v_break,
285 afs_cb_break_for_volume_callback, false);
90fa9b64 286 write_unlock(&volume->cb_v_break_lock);
68251f0a
DH
287 } else {
288 data.volume = NULL;
289 data.fid = *fid;
290 inode = ilookup5_nowait(cbi->sb, fid->vnode,
291 afs_iget5_test, &data);
292 if (inode) {
293 vnode = AFS_FS_I(inode);
051d2525 294 afs_break_callback(vnode, afs_cb_break_for_callback);
68251f0a 295 iput(inode);
051d2525
DH
296 } else {
297 trace_afs_cb_miss(fid, afs_cb_break_for_callback);
68251f0a 298 }
c435ee34
DH
299 }
300 }
08e0e7c8 301
47ea0f2e 302out:
c435ee34 303 read_unlock(&server->cb_break_lock);
ec26815a 304}
1da177e4 305
1da177e4
LT
306/*
307 * allow the fileserver to break callback promises
308 */
08e0e7c8 309void afs_break_callbacks(struct afs_server *server, size_t count,
5cf9dd55 310 struct afs_callback_break *callbacks)
1da177e4 311{
08e0e7c8 312 _enter("%p,%zu,", server, count);
1da177e4 313
08e0e7c8 314 ASSERT(server != NULL);
1da177e4 315
68251f0a
DH
316 /* TODO: Sort the callback break list by volume ID */
317
08e0e7c8 318 for (; count > 0; callbacks++, count--) {
06aeb297 319 _debug("- Fid { vl=%08llx n=%llu u=%u }",
1da177e4
LT
320 callbacks->fid.vid,
321 callbacks->fid.vnode,
06aeb297 322 callbacks->fid.unique);
08e0e7c8
DH
323 afs_break_one_callback(server, &callbacks->fid);
324 }
325
326 _leave("");
327 return;
328}
1da177e4 329
08e0e7c8 330/*
c435ee34 331 * Clear the callback interests in a server list.
08e0e7c8 332 */
d2ddc776 333void afs_clear_callback_interests(struct afs_net *net, struct afs_server_list *slist)
08e0e7c8 334{
c435ee34 335 int i;
08e0e7c8 336
d2ddc776
DH
337 for (i = 0; i < slist->nr_servers; i++) {
338 afs_put_cb_interest(net, slist->servers[i].cb_interest);
339 slist->servers[i].cb_interest = NULL;
08e0e7c8 340 }
08e0e7c8 341}