1 /*
2 * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
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 *
11 * Authors: David Woodhouse <dwmw2@infradead.org>
12 * David Howells <dhowells@redhat.com>
13 *
14 */
15
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/circ_buf.h>
20 #include <linux/sched.h>
21 #include "internal.h"
22
23 /*
24 * Allow the fileserver to request callback state (re-)initialisation.
25 * Unfortunately, UUIDs are not guaranteed unique.
26 */
afs_init_callback_state(struct afs_server * server)27 void afs_init_callback_state(struct afs_server *server)
28 {
29 rcu_read_lock();
30 do {
31 server->cb_s_break++;
32 server = rcu_dereference(server->uuid_next);
33 } while (0);
34 rcu_read_unlock();
35 }
36
37 /*
38 * actually break a callback
39 */
__afs_break_callback(struct afs_vnode * vnode,enum afs_cb_break_reason reason)40 void __afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
41 {
42 _enter("");
43
44 clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
45 if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
46 vnode->cb_break++;
47 afs_clear_permits(vnode);
48
49 if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
50 afs_lock_may_be_available(vnode);
51
52 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, true);
53 } else {
54 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, false);
55 }
56 }
57
afs_break_callback(struct afs_vnode * vnode,enum afs_cb_break_reason reason)58 void afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
59 {
60 write_seqlock(&vnode->cb_lock);
61 __afs_break_callback(vnode, reason);
62 write_sequnlock(&vnode->cb_lock);
63 }
64
65 /*
66 * Look up a volume by volume ID under RCU conditions.
67 */
afs_lookup_volume_rcu(struct afs_cell * cell,afs_volid_t vid)68 static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell,
69 afs_volid_t vid)
70 {
71 struct afs_volume *volume = NULL;
72 struct rb_node *p;
73 int seq = 0;
74
75 do {
76 /* Unfortunately, rbtree walking doesn't give reliable results
77 * under just the RCU read lock, so we have to check for
78 * changes.
79 */
80 read_seqbegin_or_lock(&cell->volume_lock, &seq);
81
82 p = rcu_dereference_raw(cell->volumes.rb_node);
83 while (p) {
84 volume = rb_entry(p, struct afs_volume, cell_node);
85
86 if (volume->vid < vid)
87 p = rcu_dereference_raw(p->rb_left);
88 else if (volume->vid > vid)
89 p = rcu_dereference_raw(p->rb_right);
90 else
91 break;
92 volume = NULL;
93 }
94
95 } while (need_seqretry(&cell->volume_lock, seq));
96
97 done_seqretry(&cell->volume_lock, seq);
98 return volume;
99 }
100
101 /*
102 * allow the fileserver to explicitly break one callback
103 * - happens when
104 * - the backing file is changed
105 * - a lock is released
106 */
afs_break_one_callback(struct afs_volume * volume,struct afs_fid * fid)107 static void afs_break_one_callback(struct afs_volume *volume,
108 struct afs_fid *fid)
109 {
110 struct super_block *sb;
111 struct afs_vnode *vnode;
112 struct inode *inode;
113
114 if (fid->vnode == 0 && fid->unique == 0) {
115 /* The callback break applies to an entire volume. */
116 write_lock(&volume->cb_v_break_lock);
117 volume->cb_v_break++;
118 trace_afs_cb_break(fid, volume->cb_v_break,
119 afs_cb_break_for_volume_callback, false);
120 write_unlock(&volume->cb_v_break_lock);
121 return;
122 }
123
124 /* See if we can find a matching inode - even an I_NEW inode needs to
125 * be marked as it can have its callback broken before we finish
126 * setting up the local inode.
127 */
128 sb = rcu_dereference(volume->sb);
129 if (!sb)
130 return;
131
132 inode = find_inode_rcu(sb, fid->vnode, afs_ilookup5_test_by_fid, fid);
133 if (inode) {
134 vnode = AFS_FS_I(inode);
135 afs_break_callback(vnode, afs_cb_break_for_callback);
136 } else {
137 trace_afs_cb_miss(fid, afs_cb_break_for_callback);
138 }
139 }
140
afs_break_some_callbacks(struct afs_server * server,struct afs_callback_break * cbb,size_t * _count)141 static void afs_break_some_callbacks(struct afs_server *server,
142 struct afs_callback_break *cbb,
143 size_t *_count)
144 {
145 struct afs_callback_break *residue = cbb;
146 struct afs_volume *volume;
147 afs_volid_t vid = cbb->fid.vid;
148 size_t i;
149
150 volume = afs_lookup_volume_rcu(server->cell, vid);
151
152 /* TODO: Find all matching volumes if we couldn't match the server and
153 * break them anyway.
154 */
155
156 for (i = *_count; i > 0; cbb++, i--) {
157 if (cbb->fid.vid == vid) {
158 _debug("- Fid { vl=%08llx n=%llu u=%u }",
159 cbb->fid.vid,
160 cbb->fid.vnode,
161 cbb->fid.unique);
162 --*_count;
163 if (volume)
164 afs_break_one_callback(volume, &cbb->fid);
165 } else {
166 *residue++ = *cbb;
167 }
168 }
169 }
170
171 /*
172 * allow the fileserver to break callback promises
173 */
afs_break_callbacks(struct afs_server * server,size_t count,struct afs_callback_break * callbacks)174 void afs_break_callbacks(struct afs_server *server, size_t count,
175 struct afs_callback_break *callbacks)
176 {
177 _enter("%p,%zu,", server, count);
178
179 ASSERT(server != NULL);
180
181 rcu_read_lock();
182
183 while (count > 0)
184 afs_break_some_callbacks(server, callbacks, &count);
185
186 rcu_read_unlock();
187 return;
188 }
189