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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Handle fileserver selection and rotation.
3 *
4 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/kernel.h>
9#include <linux/slab.h>
10#include <linux/fs.h>
11#include <linux/sched.h>
12#include <linux/delay.h>
13#include <linux/sched/signal.h>
14#include "internal.h"
15#include "afs_fs.h"
16
17/*
18 * Begin iteration through a server list, starting with the vnode's last used
19 * server if possible, or the last recorded good server if not.
20 */
21static bool afs_start_fs_iteration(struct afs_operation *op,
22 struct afs_vnode *vnode)
23{
24 struct afs_server *server;
25 void *cb_server;
26 int i;
27
28 read_lock(&op->volume->servers_lock);
29 op->server_list = afs_get_serverlist(
30 rcu_dereference_protected(op->volume->servers,
31 lockdep_is_held(&op->volume->servers_lock)));
32 read_unlock(&op->volume->servers_lock);
33
34 op->untried = (1UL << op->server_list->nr_servers) - 1;
35 op->index = READ_ONCE(op->server_list->preferred);
36
37 cb_server = vnode->cb_server;
38 if (cb_server) {
39 /* See if the vnode's preferred record is still available */
40 for (i = 0; i < op->server_list->nr_servers; i++) {
41 server = op->server_list->servers[i].server;
42 if (server == cb_server) {
43 op->index = i;
44 goto found_interest;
45 }
46 }
47
48 /* If we have a lock outstanding on a server that's no longer
49 * serving this vnode, then we can't switch to another server
50 * and have to return an error.
51 */
52 if (op->flags & AFS_OPERATION_CUR_ONLY) {
53 op->error = -ESTALE;
54 return false;
55 }
56
57 /* Note that the callback promise is effectively broken */
58 write_seqlock(&vnode->cb_lock);
59 ASSERTCMP(cb_server, ==, vnode->cb_server);
60 vnode->cb_server = NULL;
61 if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
62 vnode->cb_break++;
63 write_sequnlock(&vnode->cb_lock);
64 }
65
66found_interest:
67 return true;
68}
69
70/*
71 * Post volume busy note.
72 */
73static void afs_busy(struct afs_volume *volume, u32 abort_code)
74{
75 const char *m;
76
77 switch (abort_code) {
78 case VOFFLINE: m = "offline"; break;
79 case VRESTARTING: m = "restarting"; break;
80 case VSALVAGING: m = "being salvaged"; break;
81 default: m = "busy"; break;
82 }
83
84 pr_notice("kAFS: Volume %llu '%s' is %s\n", volume->vid, volume->name, m);
85}
86
87/*
88 * Sleep and retry the operation to the same fileserver.
89 */
90static bool afs_sleep_and_retry(struct afs_operation *op)
91{
92 if (!(op->flags & AFS_OPERATION_UNINTR)) {
93 msleep_interruptible(1000);
94 if (signal_pending(current)) {
95 op->error = -ERESTARTSYS;
96 return false;
97 }
98 } else {
99 msleep(1000);
100 }
101
102 return true;
103}
104
105/*
106 * Select the fileserver to use. May be called multiple times to rotate
107 * through the fileservers.
108 */
109bool afs_select_fileserver(struct afs_operation *op)
110{
111 struct afs_addr_list *alist;
112 struct afs_server *server;
113 struct afs_vnode *vnode = op->file[0].vnode;
114 struct afs_error e;
115 u32 rtt;
116 int error = op->ac.error, i;
117
118 _enter("%lx[%d],%lx[%d],%d,%d",
119 op->untried, op->index,
120 op->ac.tried, op->ac.index,
121 error, op->ac.abort_code);
122
123 if (op->flags & AFS_OPERATION_STOP) {
124 _leave(" = f [stopped]");
125 return false;
126 }
127
128 op->nr_iterations++;
129
130 /* Evaluate the result of the previous operation, if there was one. */
131 switch (error) {
132 case SHRT_MAX:
133 goto start;
134
135 case 0:
136 default:
137 /* Success or local failure. Stop. */
138 op->error = error;
139 op->flags |= AFS_OPERATION_STOP;
140 _leave(" = f [okay/local %d]", error);
141 return false;
142
143 case -ECONNABORTED:
144 /* The far side rejected the operation on some grounds. This
145 * might involve the server being busy or the volume having been moved.
146 */
147 switch (op->ac.abort_code) {
148 case VNOVOL:
149 /* This fileserver doesn't know about the volume.
150 * - May indicate that the VL is wrong - retry once and compare
151 * the results.
152 * - May indicate that the fileserver couldn't attach to the vol.
153 */
154 if (op->flags & AFS_OPERATION_VNOVOL) {
155 op->error = -EREMOTEIO;
156 goto next_server;
157 }
158
159 write_lock(&op->volume->servers_lock);
160 op->server_list->vnovol_mask |= 1 << op->index;
161 write_unlock(&op->volume->servers_lock);
162
163 set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
164 error = afs_check_volume_status(op->volume, op);
165 if (error < 0)
166 goto failed_set_error;
167
168 if (test_bit(AFS_VOLUME_DELETED, &op->volume->flags)) {
169 op->error = -ENOMEDIUM;
170 goto failed;
171 }
172
173 /* If the server list didn't change, then assume that
174 * it's the fileserver having trouble.
175 */
176 if (rcu_access_pointer(op->volume->servers) == op->server_list) {
177 op->error = -EREMOTEIO;
178 goto next_server;
179 }
180
181 /* Try again */
182 op->flags |= AFS_OPERATION_VNOVOL;
183 _leave(" = t [vnovol]");
184 return true;
185
186 case VSALVAGE: /* TODO: Should this return an error or iterate? */
187 case VVOLEXISTS:
188 case VNOSERVICE:
189 case VONLINE:
190 case VDISKFULL:
191 case VOVERQUOTA:
192 op->error = afs_abort_to_error(op->ac.abort_code);
193 goto next_server;
194
195 case VOFFLINE:
196 if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &op->volume->flags)) {
197 afs_busy(op->volume, op->ac.abort_code);
198 clear_bit(AFS_VOLUME_BUSY, &op->volume->flags);
199 }
200 if (op->flags & AFS_OPERATION_NO_VSLEEP) {
201 op->error = -EADV;
202 goto failed;
203 }
204 if (op->flags & AFS_OPERATION_CUR_ONLY) {
205 op->error = -ESTALE;
206 goto failed;
207 }
208 goto busy;
209
210 case VSALVAGING:
211 case VRESTARTING:
212 case VBUSY:
213 /* Retry after going round all the servers unless we
214 * have a file lock we need to maintain.
215 */
216 if (op->flags & AFS_OPERATION_NO_VSLEEP) {
217 op->error = -EBUSY;
218 goto failed;
219 }
220 if (!test_and_set_bit(AFS_VOLUME_BUSY, &op->volume->flags)) {
221 afs_busy(op->volume, op->ac.abort_code);
222 clear_bit(AFS_VOLUME_OFFLINE, &op->volume->flags);
223 }
224 busy:
225 if (op->flags & AFS_OPERATION_CUR_ONLY) {
226 if (!afs_sleep_and_retry(op))
227 goto failed;
228
229 /* Retry with same server & address */
230 _leave(" = t [vbusy]");
231 return true;
232 }
233
234 op->flags |= AFS_OPERATION_VBUSY;
235 goto next_server;
236
237 case VMOVED:
238 /* The volume migrated to another server. We consider
239 * consider all locks and callbacks broken and request
240 * an update from the VLDB.
241 *
242 * We also limit the number of VMOVED hops we will
243 * honour, just in case someone sets up a loop.
244 */
245 if (op->flags & AFS_OPERATION_VMOVED) {
246 op->error = -EREMOTEIO;
247 goto failed;
248 }
249 op->flags |= AFS_OPERATION_VMOVED;
250
251 set_bit(AFS_VOLUME_WAIT, &op->volume->flags);
252 set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
253 error = afs_check_volume_status(op->volume, op);
254 if (error < 0)
255 goto failed_set_error;
256
257 /* If the server list didn't change, then the VLDB is
258 * out of sync with the fileservers. This is hopefully
259 * a temporary condition, however, so we don't want to
260 * permanently block access to the file.
261 *
262 * TODO: Try other fileservers if we can.
263 *
264 * TODO: Retry a few times with sleeps.
265 */
266 if (rcu_access_pointer(op->volume->servers) == op->server_list) {
267 op->error = -ENOMEDIUM;
268 goto failed;
269 }
270
271 goto restart_from_beginning;
272
273 default:
274 clear_bit(AFS_VOLUME_OFFLINE, &op->volume->flags);
275 clear_bit(AFS_VOLUME_BUSY, &op->volume->flags);
276 op->error = afs_abort_to_error(op->ac.abort_code);
277 goto failed;
278 }
279
280 case -ETIMEDOUT:
281 case -ETIME:
282 if (op->error != -EDESTADDRREQ)
283 goto iterate_address;
284 fallthrough;
285 case -ERFKILL:
286 case -EADDRNOTAVAIL:
287 case -ENETUNREACH:
288 case -EHOSTUNREACH:
289 case -EHOSTDOWN:
290 case -ECONNREFUSED:
291 _debug("no conn");
292 op->error = error;
293 goto iterate_address;
294
295 case -ENETRESET:
296 pr_warn("kAFS: Peer reset %s (op=%x)\n",
297 op->type ? op->type->name : "???", op->debug_id);
298 fallthrough;
299 case -ECONNRESET:
300 _debug("call reset");
301 op->error = error;
302 goto failed;
303 }
304
305restart_from_beginning:
306 _debug("restart");
307 afs_end_cursor(&op->ac);
308 op->server = NULL;
309 afs_put_serverlist(op->net, op->server_list);
310 op->server_list = NULL;
311start:
312 _debug("start");
313 /* See if we need to do an update of the volume record. Note that the
314 * volume may have moved or even have been deleted.
315 */
316 error = afs_check_volume_status(op->volume, op);
317 if (error < 0)
318 goto failed_set_error;
319
320 if (!afs_start_fs_iteration(op, vnode))
321 goto failed;
322
323 _debug("__ VOL %llx __", op->volume->vid);
324
325pick_server:
326 _debug("pick [%lx]", op->untried);
327
328 error = afs_wait_for_fs_probes(op->server_list, op->untried);
329 if (error < 0)
330 goto failed_set_error;
331
332 /* Pick the untried server with the lowest RTT. If we have outstanding
333 * callbacks, we stick with the server we're already using if we can.
334 */
335 if (op->server) {
336 _debug("server %u", op->index);
337 if (test_bit(op->index, &op->untried))
338 goto selected_server;
339 op->server = NULL;
340 _debug("no server");
341 }
342
343 op->index = -1;
344 rtt = U32_MAX;
345 for (i = 0; i < op->server_list->nr_servers; i++) {
346 struct afs_server *s = op->server_list->servers[i].server;
347
348 if (!test_bit(i, &op->untried) ||
349 !test_bit(AFS_SERVER_FL_RESPONDING, &s->flags))
350 continue;
351 if (s->probe.rtt < rtt) {
352 op->index = i;
353 rtt = s->probe.rtt;
354 }
355 }
356
357 if (op->index == -1)
358 goto no_more_servers;
359
360selected_server:
361 _debug("use %d", op->index);
362 __clear_bit(op->index, &op->untried);
363
364 /* We're starting on a different fileserver from the list. We need to
365 * check it, create a callback intercept, find its address list and
366 * probe its capabilities before we use it.
367 */
368 ASSERTCMP(op->ac.alist, ==, NULL);
369 server = op->server_list->servers[op->index].server;
370
371 if (!afs_check_server_record(op, server))
372 goto failed;
373
374 _debug("USING SERVER: %pU", &server->uuid);
375
376 op->flags |= AFS_OPERATION_RETRY_SERVER;
377 op->server = server;
378 if (vnode->cb_server != server) {
379 vnode->cb_server = server;
380 vnode->cb_s_break = server->cb_s_break;
381 vnode->cb_fs_s_break = atomic_read(&server->cell->fs_s_break);
382 vnode->cb_v_break = vnode->volume->cb_v_break;
383 clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
384 }
385
386 read_lock(&server->fs_lock);
387 alist = rcu_dereference_protected(server->addresses,
388 lockdep_is_held(&server->fs_lock));
389 afs_get_addrlist(alist);
390 read_unlock(&server->fs_lock);
391
392retry_server:
393 memset(&op->ac, 0, sizeof(op->ac));
394
395 if (!op->ac.alist)
396 op->ac.alist = alist;
397 else
398 afs_put_addrlist(alist);
399
400 op->ac.index = -1;
401
402iterate_address:
403 ASSERT(op->ac.alist);
404 /* Iterate over the current server's address list to try and find an
405 * address on which it will respond to us.
406 */
407 if (!afs_iterate_addresses(&op->ac))
408 goto out_of_addresses;
409
410 _debug("address [%u] %u/%u %pISp",
411 op->index, op->ac.index, op->ac.alist->nr_addrs,
412 &op->ac.alist->addrs[op->ac.index].transport);
413
414 _leave(" = t");
415 return true;
416
417out_of_addresses:
418 /* We've now had a failure to respond on all of a server's addresses -
419 * immediately probe them again and consider retrying the server.
420 */
421 afs_probe_fileserver(op->net, op->server);
422 if (op->flags & AFS_OPERATION_RETRY_SERVER) {
423 alist = op->ac.alist;
424 error = afs_wait_for_one_fs_probe(
425 op->server, !(op->flags & AFS_OPERATION_UNINTR));
426 switch (error) {
427 case 0:
428 op->flags &= ~AFS_OPERATION_RETRY_SERVER;
429 goto retry_server;
430 case -ERESTARTSYS:
431 goto failed_set_error;
432 case -ETIME:
433 case -EDESTADDRREQ:
434 goto next_server;
435 }
436 }
437
438next_server:
439 _debug("next");
440 afs_end_cursor(&op->ac);
441 goto pick_server;
442
443no_more_servers:
444 /* That's all the servers poked to no good effect. Try again if some
445 * of them were busy.
446 */
447 if (op->flags & AFS_OPERATION_VBUSY)
448 goto restart_from_beginning;
449
450 e.error = -EDESTADDRREQ;
451 e.responded = false;
452 for (i = 0; i < op->server_list->nr_servers; i++) {
453 struct afs_server *s = op->server_list->servers[i].server;
454
455 afs_prioritise_error(&e, READ_ONCE(s->probe.error),
456 s->probe.abort_code);
457 }
458
459 error = e.error;
460
461failed_set_error:
462 op->error = error;
463failed:
464 op->flags |= AFS_OPERATION_STOP;
465 afs_end_cursor(&op->ac);
466 _leave(" = f [failed %d]", op->error);
467 return false;
468}
469
470/*
471 * Dump cursor state in the case of the error being EDESTADDRREQ.
472 */
473void afs_dump_edestaddrreq(const struct afs_operation *op)
474{
475 static int count;
476 int i;
477
478 if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)
479 return;
480 count++;
481
482 rcu_read_lock();
483
484 pr_notice("EDESTADDR occurred\n");
485 pr_notice("FC: cbb=%x cbb2=%x fl=%x err=%hd\n",
486 op->file[0].cb_break_before,
487 op->file[1].cb_break_before, op->flags, op->error);
488 pr_notice("FC: ut=%lx ix=%d ni=%u\n",
489 op->untried, op->index, op->nr_iterations);
490
491 if (op->server_list) {
492 const struct afs_server_list *sl = op->server_list;
493 pr_notice("FC: SL nr=%u pr=%u vnov=%hx\n",
494 sl->nr_servers, sl->preferred, sl->vnovol_mask);
495 for (i = 0; i < sl->nr_servers; i++) {
496 const struct afs_server *s = sl->servers[i].server;
497 pr_notice("FC: server fl=%lx av=%u %pU\n",
498 s->flags, s->addr_version, &s->uuid);
499 if (s->addresses) {
500 const struct afs_addr_list *a =
501 rcu_dereference(s->addresses);
502 pr_notice("FC: - av=%u nr=%u/%u/%u pr=%u\n",
503 a->version,
504 a->nr_ipv4, a->nr_addrs, a->max_addrs,
505 a->preferred);
506 pr_notice("FC: - R=%lx F=%lx\n",
507 a->responded, a->failed);
508 if (a == op->ac.alist)
509 pr_notice("FC: - current\n");
510 }
511 }
512 }
513
514 pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
515 op->ac.tried, op->ac.index, op->ac.abort_code, op->ac.error,
516 op->ac.responded, op->ac.nr_iterations);
517 rcu_read_unlock();
518}
1/* Handle fileserver selection and rotation.
2 *
3 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/fs.h>
15#include <linux/sched.h>
16#include <linux/delay.h>
17#include <linux/sched/signal.h>
18#include "internal.h"
19#include "afs_fs.h"
20
21/*
22 * Initialise a filesystem server cursor for iterating over FS servers.
23 */
24static void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
25{
26 memset(fc, 0, sizeof(*fc));
27}
28
29/*
30 * Begin an operation on the fileserver.
31 *
32 * Fileserver operations are serialised on the server by vnode, so we serialise
33 * them here also using the io_lock.
34 */
35bool afs_begin_vnode_operation(struct afs_fs_cursor *fc, struct afs_vnode *vnode,
36 struct key *key)
37{
38 afs_init_fs_cursor(fc, vnode);
39 fc->vnode = vnode;
40 fc->key = key;
41 fc->ac.error = SHRT_MAX;
42
43 if (mutex_lock_interruptible(&vnode->io_lock) < 0) {
44 fc->ac.error = -EINTR;
45 fc->flags |= AFS_FS_CURSOR_STOP;
46 return false;
47 }
48
49 if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
50 fc->flags |= AFS_FS_CURSOR_CUR_ONLY;
51 return true;
52}
53
54/*
55 * Begin iteration through a server list, starting with the vnode's last used
56 * server if possible, or the last recorded good server if not.
57 */
58static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
59 struct afs_vnode *vnode)
60{
61 struct afs_cb_interest *cbi;
62 int i;
63
64 read_lock(&vnode->volume->servers_lock);
65 fc->server_list = afs_get_serverlist(vnode->volume->servers);
66 read_unlock(&vnode->volume->servers_lock);
67
68 cbi = vnode->cb_interest;
69 if (cbi) {
70 /* See if the vnode's preferred record is still available */
71 for (i = 0; i < fc->server_list->nr_servers; i++) {
72 if (fc->server_list->servers[i].cb_interest == cbi) {
73 fc->start = i;
74 goto found_interest;
75 }
76 }
77
78 /* If we have a lock outstanding on a server that's no longer
79 * serving this vnode, then we can't switch to another server
80 * and have to return an error.
81 */
82 if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
83 fc->ac.error = -ESTALE;
84 return false;
85 }
86
87 /* Note that the callback promise is effectively broken */
88 write_seqlock(&vnode->cb_lock);
89 ASSERTCMP(cbi, ==, vnode->cb_interest);
90 vnode->cb_interest = NULL;
91 if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
92 vnode->cb_break++;
93 write_sequnlock(&vnode->cb_lock);
94
95 afs_put_cb_interest(afs_v2net(vnode), cbi);
96 cbi = NULL;
97 } else {
98 fc->start = READ_ONCE(fc->server_list->index);
99 }
100
101found_interest:
102 fc->index = fc->start;
103 return true;
104}
105
106/*
107 * Post volume busy note.
108 */
109static void afs_busy(struct afs_volume *volume, u32 abort_code)
110{
111 const char *m;
112
113 switch (abort_code) {
114 case VOFFLINE: m = "offline"; break;
115 case VRESTARTING: m = "restarting"; break;
116 case VSALVAGING: m = "being salvaged"; break;
117 default: m = "busy"; break;
118 }
119
120 pr_notice("kAFS: Volume %u '%s' is %s\n", volume->vid, volume->name, m);
121}
122
123/*
124 * Sleep and retry the operation to the same fileserver.
125 */
126static bool afs_sleep_and_retry(struct afs_fs_cursor *fc)
127{
128 msleep_interruptible(1000);
129 if (signal_pending(current)) {
130 fc->ac.error = -ERESTARTSYS;
131 return false;
132 }
133
134 return true;
135}
136
137/*
138 * Select the fileserver to use. May be called multiple times to rotate
139 * through the fileservers.
140 */
141bool afs_select_fileserver(struct afs_fs_cursor *fc)
142{
143 struct afs_addr_list *alist;
144 struct afs_server *server;
145 struct afs_vnode *vnode = fc->vnode;
146
147 _enter("%u/%u,%u/%u,%d,%d",
148 fc->index, fc->start,
149 fc->ac.index, fc->ac.start,
150 fc->ac.error, fc->ac.abort_code);
151
152 if (fc->flags & AFS_FS_CURSOR_STOP) {
153 _leave(" = f [stopped]");
154 return false;
155 }
156
157 /* Evaluate the result of the previous operation, if there was one. */
158 switch (fc->ac.error) {
159 case SHRT_MAX:
160 goto start;
161
162 case 0:
163 default:
164 /* Success or local failure. Stop. */
165 fc->flags |= AFS_FS_CURSOR_STOP;
166 _leave(" = f [okay/local %d]", fc->ac.error);
167 return false;
168
169 case -ECONNABORTED:
170 /* The far side rejected the operation on some grounds. This
171 * might involve the server being busy or the volume having been moved.
172 */
173 switch (fc->ac.abort_code) {
174 case VNOVOL:
175 /* This fileserver doesn't know about the volume.
176 * - May indicate that the VL is wrong - retry once and compare
177 * the results.
178 * - May indicate that the fileserver couldn't attach to the vol.
179 */
180 if (fc->flags & AFS_FS_CURSOR_VNOVOL) {
181 fc->ac.error = -EREMOTEIO;
182 goto next_server;
183 }
184
185 write_lock(&vnode->volume->servers_lock);
186 fc->server_list->vnovol_mask |= 1 << fc->index;
187 write_unlock(&vnode->volume->servers_lock);
188
189 set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
190 fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
191 if (fc->ac.error < 0)
192 goto failed;
193
194 if (test_bit(AFS_VOLUME_DELETED, &vnode->volume->flags)) {
195 fc->ac.error = -ENOMEDIUM;
196 goto failed;
197 }
198
199 /* If the server list didn't change, then assume that
200 * it's the fileserver having trouble.
201 */
202 if (vnode->volume->servers == fc->server_list) {
203 fc->ac.error = -EREMOTEIO;
204 goto next_server;
205 }
206
207 /* Try again */
208 fc->flags |= AFS_FS_CURSOR_VNOVOL;
209 _leave(" = t [vnovol]");
210 return true;
211
212 case VSALVAGE: /* TODO: Should this return an error or iterate? */
213 case VVOLEXISTS:
214 case VNOSERVICE:
215 case VONLINE:
216 case VDISKFULL:
217 case VOVERQUOTA:
218 fc->ac.error = afs_abort_to_error(fc->ac.abort_code);
219 goto next_server;
220
221 case VOFFLINE:
222 if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags)) {
223 afs_busy(vnode->volume, fc->ac.abort_code);
224 clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
225 }
226 if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
227 fc->ac.error = -EADV;
228 goto failed;
229 }
230 if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
231 fc->ac.error = -ESTALE;
232 goto failed;
233 }
234 goto busy;
235
236 case VSALVAGING:
237 case VRESTARTING:
238 case VBUSY:
239 /* Retry after going round all the servers unless we
240 * have a file lock we need to maintain.
241 */
242 if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
243 fc->ac.error = -EBUSY;
244 goto failed;
245 }
246 if (!test_and_set_bit(AFS_VOLUME_BUSY, &vnode->volume->flags)) {
247 afs_busy(vnode->volume, fc->ac.abort_code);
248 clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
249 }
250 busy:
251 if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
252 if (!afs_sleep_and_retry(fc))
253 goto failed;
254
255 /* Retry with same server & address */
256 _leave(" = t [vbusy]");
257 return true;
258 }
259
260 fc->flags |= AFS_FS_CURSOR_VBUSY;
261 goto next_server;
262
263 case VMOVED:
264 /* The volume migrated to another server. We consider
265 * consider all locks and callbacks broken and request
266 * an update from the VLDB.
267 *
268 * We also limit the number of VMOVED hops we will
269 * honour, just in case someone sets up a loop.
270 */
271 if (fc->flags & AFS_FS_CURSOR_VMOVED) {
272 fc->ac.error = -EREMOTEIO;
273 goto failed;
274 }
275 fc->flags |= AFS_FS_CURSOR_VMOVED;
276
277 set_bit(AFS_VOLUME_WAIT, &vnode->volume->flags);
278 set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
279 fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
280 if (fc->ac.error < 0)
281 goto failed;
282
283 /* If the server list didn't change, then the VLDB is
284 * out of sync with the fileservers. This is hopefully
285 * a temporary condition, however, so we don't want to
286 * permanently block access to the file.
287 *
288 * TODO: Try other fileservers if we can.
289 *
290 * TODO: Retry a few times with sleeps.
291 */
292 if (vnode->volume->servers == fc->server_list) {
293 fc->ac.error = -ENOMEDIUM;
294 goto failed;
295 }
296
297 goto restart_from_beginning;
298
299 default:
300 clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
301 clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
302 fc->ac.error = afs_abort_to_error(fc->ac.abort_code);
303 goto failed;
304 }
305
306 case -ENETUNREACH:
307 case -EHOSTUNREACH:
308 case -ECONNREFUSED:
309 case -ETIMEDOUT:
310 case -ETIME:
311 _debug("no conn");
312 goto iterate_address;
313 }
314
315restart_from_beginning:
316 _debug("restart");
317 afs_end_cursor(&fc->ac);
318 afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
319 fc->cbi = NULL;
320 afs_put_serverlist(afs_v2net(vnode), fc->server_list);
321 fc->server_list = NULL;
322start:
323 _debug("start");
324 /* See if we need to do an update of the volume record. Note that the
325 * volume may have moved or even have been deleted.
326 */
327 fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
328 if (fc->ac.error < 0)
329 goto failed;
330
331 if (!afs_start_fs_iteration(fc, vnode))
332 goto failed;
333
334use_server:
335 _debug("use");
336 /* We're starting on a different fileserver from the list. We need to
337 * check it, create a callback intercept, find its address list and
338 * probe its capabilities before we use it.
339 */
340 ASSERTCMP(fc->ac.alist, ==, NULL);
341 server = fc->server_list->servers[fc->index].server;
342
343 if (!afs_check_server_record(fc, server))
344 goto failed;
345
346 _debug("USING SERVER: %pU", &server->uuid);
347
348 /* Make sure we've got a callback interest record for this server. We
349 * have to link it in before we send the request as we can be sent a
350 * break request before we've finished decoding the reply and
351 * installing the vnode.
352 */
353 fc->ac.error = afs_register_server_cb_interest(vnode, fc->server_list,
354 fc->index);
355 if (fc->ac.error < 0)
356 goto failed;
357
358 fc->cbi = afs_get_cb_interest(vnode->cb_interest);
359
360 read_lock(&server->fs_lock);
361 alist = rcu_dereference_protected(server->addresses,
362 lockdep_is_held(&server->fs_lock));
363 afs_get_addrlist(alist);
364 read_unlock(&server->fs_lock);
365
366 memset(&fc->ac, 0, sizeof(fc->ac));
367
368 /* Probe the current fileserver if we haven't done so yet. */
369 if (!test_bit(AFS_SERVER_FL_PROBED, &server->flags)) {
370 fc->ac.alist = afs_get_addrlist(alist);
371
372 if (!afs_probe_fileserver(fc)) {
373 switch (fc->ac.error) {
374 case -ENOMEM:
375 case -ERESTARTSYS:
376 case -EINTR:
377 goto failed;
378 default:
379 goto next_server;
380 }
381 }
382 }
383
384 if (!fc->ac.alist)
385 fc->ac.alist = alist;
386 else
387 afs_put_addrlist(alist);
388
389 fc->ac.start = READ_ONCE(alist->index);
390 fc->ac.index = fc->ac.start;
391
392iterate_address:
393 ASSERT(fc->ac.alist);
394 _debug("iterate %d/%d", fc->ac.index, fc->ac.alist->nr_addrs);
395 /* Iterate over the current server's address list to try and find an
396 * address on which it will respond to us.
397 */
398 if (!afs_iterate_addresses(&fc->ac))
399 goto next_server;
400
401 _leave(" = t");
402 return true;
403
404next_server:
405 _debug("next");
406 afs_end_cursor(&fc->ac);
407 afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
408 fc->cbi = NULL;
409 fc->index++;
410 if (fc->index >= fc->server_list->nr_servers)
411 fc->index = 0;
412 if (fc->index != fc->start)
413 goto use_server;
414
415 /* That's all the servers poked to no good effect. Try again if some
416 * of them were busy.
417 */
418 if (fc->flags & AFS_FS_CURSOR_VBUSY)
419 goto restart_from_beginning;
420
421 fc->ac.error = -EDESTADDRREQ;
422 goto failed;
423
424failed:
425 fc->flags |= AFS_FS_CURSOR_STOP;
426 afs_end_cursor(&fc->ac);
427 _leave(" = f [failed %d]", fc->ac.error);
428 return false;
429}
430
431/*
432 * Select the same fileserver we used for a vnode before and only that
433 * fileserver. We use this when we have a lock on that file, which is backed
434 * only by the fileserver we obtained it from.
435 */
436bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
437{
438 struct afs_vnode *vnode = fc->vnode;
439 struct afs_cb_interest *cbi = vnode->cb_interest;
440 struct afs_addr_list *alist;
441
442 _enter("");
443
444 switch (fc->ac.error) {
445 case SHRT_MAX:
446 if (!cbi) {
447 fc->ac.error = -ESTALE;
448 fc->flags |= AFS_FS_CURSOR_STOP;
449 return false;
450 }
451
452 fc->cbi = afs_get_cb_interest(vnode->cb_interest);
453
454 read_lock(&cbi->server->fs_lock);
455 alist = rcu_dereference_protected(cbi->server->addresses,
456 lockdep_is_held(&cbi->server->fs_lock));
457 afs_get_addrlist(alist);
458 read_unlock(&cbi->server->fs_lock);
459 if (!alist) {
460 fc->ac.error = -ESTALE;
461 fc->flags |= AFS_FS_CURSOR_STOP;
462 return false;
463 }
464
465 memset(&fc->ac, 0, sizeof(fc->ac));
466 fc->ac.alist = alist;
467 fc->ac.start = READ_ONCE(alist->index);
468 fc->ac.index = fc->ac.start;
469 goto iterate_address;
470
471 case 0:
472 default:
473 /* Success or local failure. Stop. */
474 fc->flags |= AFS_FS_CURSOR_STOP;
475 _leave(" = f [okay/local %d]", fc->ac.error);
476 return false;
477
478 case -ECONNABORTED:
479 fc->flags |= AFS_FS_CURSOR_STOP;
480 _leave(" = f [abort]");
481 return false;
482
483 case -ENETUNREACH:
484 case -EHOSTUNREACH:
485 case -ECONNREFUSED:
486 case -ETIMEDOUT:
487 case -ETIME:
488 _debug("no conn");
489 goto iterate_address;
490 }
491
492iterate_address:
493 /* Iterate over the current server's address list to try and find an
494 * address on which it will respond to us.
495 */
496 if (afs_iterate_addresses(&fc->ac)) {
497 _leave(" = t");
498 return true;
499 }
500
501 afs_end_cursor(&fc->ac);
502 return false;
503}
504
505/*
506 * Tidy up a filesystem cursor and unlock the vnode.
507 */
508int afs_end_vnode_operation(struct afs_fs_cursor *fc)
509{
510 struct afs_net *net = afs_v2net(fc->vnode);
511 int ret;
512
513 mutex_unlock(&fc->vnode->io_lock);
514
515 afs_end_cursor(&fc->ac);
516 afs_put_cb_interest(net, fc->cbi);
517 afs_put_serverlist(net, fc->server_list);
518
519 ret = fc->ac.error;
520 if (ret == -ECONNABORTED)
521 afs_abort_to_error(fc->ac.abort_code);
522
523 return fc->ac.error;
524}