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 * 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(mapping: vnode->netfs.inode.i_mapping, start: 0, nr: 0, even_cows: false);
34}
35
36static void afs_volume_init_callback(struct afs_volume *volume)
37{
38 struct afs_vnode *vnode;
39
40 down_read(sem: &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(v: &volume->cb_v_break)) {
44 atomic64_set(v: &vnode->cb_expires_at, AFS_NO_CB_PROMISE);
45 queue_work(wq: system_unbound_wq, work: &vnode->cb_work);
46 }
47 }
48
49 up_read(sem: &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(sem: &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(vid: se->volume->vid, cb_v_break: atomic_read(v: &se->volume->cb_v_break),
66 reason: afs_cb_break_for_s_reinit);
67 if (!list_empty(head: &se->volume->open_mmaps))
68 afs_volume_init_callback(volume: se->volume);
69 }
70
71 up_read(sem: &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, addr: &vnode->flags);
82 if (atomic64_xchg(v: &vnode->cb_expires_at, AFS_NO_CB_PROMISE) != AFS_NO_CB_PROMISE) {
83 vnode->cb_break++;
84 vnode->cb_v_check = atomic_read(v: &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(v: &vnode->cb_nr_mmap))
93 queue_work(wq: system_unbound_wq, work: &vnode->cb_work);
94
95 trace_afs_cb_break(fid: &vnode->fid, cb_break: vnode->cb_break, reason, skipped: true);
96 } else {
97 trace_afs_cb_break(fid: &vnode->fid, cb_break: vnode->cb_break, reason, skipped: false);
98 }
99}
100
101void afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
102{
103 write_seqlock(sl: &vnode->cb_lock);
104 __afs_break_callback(vnode, reason);
105 write_sequnlock(sl: &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 int seq = 1;
117
118 for (;;) {
119 /* Unfortunately, rbtree walking doesn't give reliable results
120 * under just the RCU read lock, so we have to check for
121 * changes.
122 */
123 seq++; /* 2 on the 1st/lockless path, otherwise odd */
124 read_seqbegin_or_lock(lock: &cell->volume_lock, seq: &seq);
125
126 p = rcu_dereference_raw(cell->volumes.rb_node);
127 while (p) {
128 volume = rb_entry(p, struct afs_volume, cell_node);
129
130 if (volume->vid < vid)
131 p = rcu_dereference_raw(p->rb_left);
132 else if (volume->vid > vid)
133 p = rcu_dereference_raw(p->rb_right);
134 else
135 break;
136 volume = NULL;
137 }
138
139 if (volume && afs_try_get_volume(volume, reason: afs_volume_trace_get_callback))
140 break;
141 if (!need_seqretry(lock: &cell->volume_lock, seq))
142 break;
143 seq |= 1; /* Want a lock next time */
144 }
145
146 done_seqretry(lock: &cell->volume_lock, seq);
147 return volume;
148}
149
150/*
151 * Allow the fileserver to break callbacks at the volume-level. This is
152 * typically done when, for example, a R/W volume is snapshotted to a R/O
153 * volume (the only way to change an R/O volume). It may also, however, happen
154 * when a volserver takes control of a volume (offlining it, moving it, etc.).
155 *
156 * Every file in that volume will need to be reevaluated.
157 */
158static void afs_break_volume_callback(struct afs_server *server,
159 struct afs_volume *volume)
160 __releases(RCU)
161{
162 struct afs_server_list *slist = rcu_dereference(volume->servers);
163 unsigned int i, cb_v_break;
164
165 write_lock(&volume->cb_v_break_lock);
166
167 for (i = 0; i < slist->nr_servers; i++)
168 if (slist->servers[i].server == server)
169 slist->servers[i].cb_expires_at = AFS_NO_CB_PROMISE;
170 volume->cb_expires_at = AFS_NO_CB_PROMISE;
171
172 cb_v_break = atomic_inc_return_release(v: &volume->cb_v_break);
173 trace_afs_cb_v_break(vid: volume->vid, cb_v_break, reason: afs_cb_break_for_volume_callback);
174
175 write_unlock(&volume->cb_v_break_lock);
176 rcu_read_unlock();
177
178 if (!list_empty(head: &volume->open_mmaps))
179 afs_volume_init_callback(volume);
180}
181
182/*
183 * allow the fileserver to explicitly break one callback
184 * - happens when
185 * - the backing file is changed
186 * - a lock is released
187 */
188static void afs_break_one_callback(struct afs_server *server,
189 struct afs_volume *volume,
190 struct afs_fid *fid)
191{
192 struct super_block *sb;
193 struct afs_vnode *vnode;
194 struct inode *inode;
195
196 /* See if we can find a matching inode - even an I_NEW inode needs to
197 * be marked as it can have its callback broken before we finish
198 * setting up the local inode.
199 */
200 sb = rcu_dereference(volume->sb);
201 if (!sb)
202 return;
203
204 inode = find_inode_rcu(sb, fid->vnode, afs_ilookup5_test_by_fid, fid);
205 if (inode) {
206 vnode = AFS_FS_I(inode);
207 afs_break_callback(vnode, reason: afs_cb_break_for_callback);
208 } else {
209 trace_afs_cb_miss(fid, reason: afs_cb_break_for_callback);
210 }
211}
212
213static void afs_break_some_callbacks(struct afs_server *server,
214 struct afs_callback_break *cbb,
215 size_t *_count)
216{
217 struct afs_callback_break *residue = cbb;
218 struct afs_volume *volume;
219 afs_volid_t vid = cbb->fid.vid;
220 size_t i;
221
222 rcu_read_lock();
223 volume = afs_lookup_volume_rcu(cell: server->cell, vid);
224 if (cbb->fid.vnode == 0 && cbb->fid.unique == 0) {
225 afs_break_volume_callback(server, volume);
226 *_count -= 1;
227 if (*_count)
228 memmove(cbb, cbb + 1, sizeof(*cbb) * *_count);
229 } else {
230 /* TODO: Find all matching volumes if we couldn't match the server and
231 * break them anyway.
232 */
233
234 for (i = *_count; i > 0; cbb++, i--) {
235 if (cbb->fid.vid == vid) {
236 _debug("- Fid { vl=%08llx n=%llu u=%u }",
237 cbb->fid.vid,
238 cbb->fid.vnode,
239 cbb->fid.unique);
240 --*_count;
241 if (volume)
242 afs_break_one_callback(server, volume, fid: &cbb->fid);
243 } else {
244 *residue++ = *cbb;
245 }
246 }
247 rcu_read_unlock();
248 }
249
250 afs_put_volume(volume, reason: afs_volume_trace_put_callback);
251}
252
253/*
254 * allow the fileserver to break callback promises
255 */
256void afs_break_callbacks(struct afs_server *server, size_t count,
257 struct afs_callback_break *callbacks)
258{
259 _enter("%p,%zu,", server, count);
260
261 ASSERT(server != NULL);
262
263 while (count > 0)
264 afs_break_some_callbacks(server, cbb: callbacks, count: &count);
265}
266

source code of linux/fs/afs/callback.c