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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 <[email protected]>
12 * David Howells <[email protected]>
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 * Handle invalidation of an mmap'd file. We invalidate all the PTEs referring
25 * to the pages in this file's pagecache, forcing the kernel to go through
26 * ->fault() or ->page_mkwrite() - at which point we can handle invalidation
27 * more fully.
28 */
29void afs_invalidate_mmap_work(struct work_struct *work)
30{
31 struct afs_vnode *vnode = container_of(work, struct afs_vnode, cb_work);
32
33 unmap_mapping_pages(vnode->netfs.inode.i_mapping, 0, 0, false);
34}
35
36static void afs_volume_init_callback(struct afs_volume *volume)
37{
38 struct afs_vnode *vnode;
39
40 down_read(&volume->open_mmaps_lock);
41
42 list_for_each_entry(vnode, &volume->open_mmaps, cb_mmap_link) {
43 if (vnode->cb_v_check != atomic_read(&volume->cb_v_break)) {
44 afs_clear_cb_promise(vnode, afs_cb_promise_clear_vol_init_cb);
45 queue_work(system_dfl_wq, &vnode->cb_work);
46 }
47 }
48
49 up_read(&volume->open_mmaps_lock);
50}
51
52/*
53 * Allow the fileserver to request callback state (re-)initialisation.
54 * Unfortunately, UUIDs are not guaranteed unique.
55 */
56void afs_init_callback_state(struct afs_server *server)
57{
58 struct afs_server_entry *se;
59
60 down_read(&server->cell->vs_lock);
61
62 list_for_each_entry(se, &server->volumes, slink) {
63 se->cb_expires_at = AFS_NO_CB_PROMISE;
64 se->volume->cb_expires_at = AFS_NO_CB_PROMISE;
65 trace_afs_cb_v_break(se->volume->vid, atomic_read(&se->volume->cb_v_break),
66 afs_cb_break_for_s_reinit);
67 if (!list_empty(&se->volume->open_mmaps))
68 afs_volume_init_callback(se->volume);
69 }
70
71 up_read(&server->cell->vs_lock);
72}
73
74/*
75 * actually break a callback
76 */
77void __afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
78{
79 _enter("");
80
81 clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
82 if (afs_clear_cb_promise(vnode, afs_cb_promise_clear_cb_break)) {
83 vnode->cb_break++;
84 vnode->cb_v_check = atomic_read(&vnode->volume->cb_v_break);
85 afs_clear_permits(vnode);
86
87 if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
88 afs_lock_may_be_available(vnode);
89
90 if (reason != afs_cb_break_for_deleted &&
91 vnode->status.type == AFS_FTYPE_FILE &&
92 atomic_read(&vnode->cb_nr_mmap))
93 queue_work(system_dfl_wq, &vnode->cb_work);
94
95 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, true);
96 } else {
97 trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, false);
98 }
99}
100
101void afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
102{
103 write_seqlock(&vnode->cb_lock);
104 __afs_break_callback(vnode, reason);
105 write_sequnlock(&vnode->cb_lock);
106}
107
108/*
109 * Look up a volume by volume ID under RCU conditions.
110 */
111static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell,
112 afs_volid_t vid)
113{
114 struct afs_volume *volume = NULL;
115 struct rb_node *p;
116
117 scoped_seqlock_read(&cell->volume_lock, ss_lock) {
118 /* Unfortunately, rbtree walking doesn't give reliable results
119 * under just the RCU read lock, so we have to check for
120 * changes.
121 */
122 p = rcu_dereference_raw(cell->volumes.rb_node);
123 while (p) {
124 volume = rb_entry(p, struct afs_volume, cell_node);
125
126 if (volume->vid < vid)
127 p = rcu_dereference_raw(p->rb_left);
128 else if (volume->vid > vid)
129 p = rcu_dereference_raw(p->rb_right);
130 else
131 break;
132 volume = NULL;
133 }
134
135 if (volume && afs_try_get_volume(volume, afs_volume_trace_get_callback))
136 break;
137 volume = NULL;
138 }
139
140 return volume;
141}
142
143/*
144 * Allow the fileserver to break callbacks at the volume-level. This is
145 * typically done when, for example, a R/W volume is snapshotted to a R/O
146 * volume (the only way to change an R/O volume). It may also, however, happen
147 * when a volserver takes control of a volume (offlining it, moving it, etc.).
148 *
149 * Every file in that volume will need to be reevaluated.
150 */
151static void afs_break_volume_callback(struct afs_server *server,
152 struct afs_volume *volume)
153 __releases(RCU)
154{
155 struct afs_server_list *slist = rcu_dereference(volume->servers);
156 unsigned int i, cb_v_break;
157
158 write_lock(&volume->cb_v_break_lock);
159
160 for (i = 0; i < slist->nr_servers; i++)
161 if (slist->servers[i].server == server)
162 slist->servers[i].cb_expires_at = AFS_NO_CB_PROMISE;
163 volume->cb_expires_at = AFS_NO_CB_PROMISE;
164
165 cb_v_break = atomic_inc_return_release(&volume->cb_v_break);
166 trace_afs_cb_v_break(volume->vid, cb_v_break, afs_cb_break_for_volume_callback);
167
168 write_unlock(&volume->cb_v_break_lock);
169 rcu_read_unlock();
170
171 if (!list_empty(&volume->open_mmaps))
172 afs_volume_init_callback(volume);
173}
174
175/*
176 * allow the fileserver to explicitly break one callback
177 * - happens when
178 * - the backing file is changed
179 * - a lock is released
180 */
181static void afs_break_one_callback(struct afs_server *server,
182 struct afs_volume *volume,
183 struct afs_fid *fid)
184{
185 struct super_block *sb;
186 struct afs_vnode *vnode;
187 struct inode *inode;
188
189 /* See if we can find a matching inode - even an I_NEW inode needs to
190 * be marked as it can have its callback broken before we finish
191 * setting up the local inode.
192 */
193 sb = rcu_dereference(volume->sb);
194 if (!sb)
195 return;
196
197 inode = find_inode_rcu(sb, fid->vnode, afs_ilookup5_test_by_fid, fid);
198 if (inode) {
199 vnode = AFS_FS_I(inode);
200 afs_break_callback(vnode, afs_cb_break_for_callback);
201 } else {
202 trace_afs_cb_miss(fid, afs_cb_break_for_callback);
203 }
204}
205
206static void afs_break_some_callbacks(struct afs_server *server,
207 struct afs_callback_break *cbb,
208 size_t *_count)
209{
210 struct afs_callback_break *residue = cbb;
211 struct afs_volume *volume;
212 afs_volid_t vid = cbb->fid.vid;
213 size_t i;
214
215 rcu_read_lock();
216 volume = afs_lookup_volume_rcu(server->cell, vid);
217 if (!volume) {
218 /* Ignore breaks on unknown volumes. */
219 rcu_read_unlock();
220 *_count = 0;
221 } else if (cbb->fid.vnode == 0 && cbb->fid.unique == 0) {
222 afs_break_volume_callback(server, volume);
223 *_count -= 1;
224 if (*_count)
225 memmove(cbb, cbb + 1, sizeof(*cbb) * *_count);
226 } else {
227 /* TODO: Find all matching volumes if we couldn't match the server and
228 * break them anyway.
229 */
230
231 for (i = *_count; i > 0; cbb++, i--) {
232 if (cbb->fid.vid == vid) {
233 _debug("- Fid { vl=%08llx n=%llu u=%u }",
234 cbb->fid.vid,
235 cbb->fid.vnode,
236 cbb->fid.unique);
237 --*_count;
238 if (volume)
239 afs_break_one_callback(server, volume, &cbb->fid);
240 } else {
241 *residue++ = *cbb;
242 }
243 }
244 rcu_read_unlock();
245 }
246
247 afs_put_volume(volume, afs_volume_trace_put_callback);
248}
249
250/*
251 * allow the fileserver to break callback promises
252 */
253void afs_break_callbacks(struct afs_server *server, size_t count,
254 struct afs_callback_break *callbacks)
255{
256 _enter("%p,%zu,", server, count);
257
258 ASSERT(server != NULL);
259
260 while (count > 0)
261 afs_break_some_callbacks(server, callbacks, &count);
262}