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1 /* Handle fileserver selection and rotation.
3 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/kernel.h>
13 #include <linux/slab.h>
15 #include <linux/sched.h>
16 #include <linux/delay.h>
17 #include <linux/sched/signal.h>
22 * Initialise a filesystem server cursor for iterating over FS servers.
24 void afs_init_fs_cursor(struct afs_fs_cursor
*fc
, struct afs_vnode
*vnode
)
26 memset(fc
, 0, sizeof(*fc
));
30 * Begin an operation on the fileserver.
32 * Fileserver operations are serialised on the server by vnode, so we serialise
33 * them here also using the io_lock.
35 bool afs_begin_vnode_operation(struct afs_fs_cursor
*fc
, struct afs_vnode
*vnode
,
38 afs_init_fs_cursor(fc
, vnode
);
41 fc
->ac
.error
= SHRT_MAX
;
43 if (mutex_lock_interruptible(&vnode
->io_lock
) < 0) {
44 fc
->ac
.error
= -EINTR
;
45 fc
->flags
|= AFS_FS_CURSOR_STOP
;
49 if (vnode
->lock_state
!= AFS_VNODE_LOCK_NONE
)
50 fc
->flags
|= AFS_FS_CURSOR_CUR_ONLY
;
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.
58 static bool afs_start_fs_iteration(struct afs_fs_cursor
*fc
,
59 struct afs_vnode
*vnode
)
61 struct afs_cb_interest
*cbi
;
64 read_lock(&vnode
->volume
->servers_lock
);
65 fc
->server_list
= afs_get_serverlist(vnode
->volume
->servers
);
66 read_unlock(&vnode
->volume
->servers_lock
);
68 cbi
= vnode
->cb_interest
;
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
) {
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.
82 if (fc
->flags
& AFS_FS_CURSOR_CUR_ONLY
) {
83 fc
->ac
.error
= -ESTALE
;
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
))
93 write_sequnlock(&vnode
->cb_lock
);
95 afs_put_cb_interest(afs_v2net(vnode
), cbi
);
98 fc
->start
= READ_ONCE(fc
->server_list
->index
);
102 fc
->index
= fc
->start
;
107 * Post volume busy note.
109 static void afs_busy(struct afs_volume
*volume
, u32 abort_code
)
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;
120 pr_notice("kAFS: Volume %u '%s' is %s\n", volume
->vid
, volume
->name
, m
);
124 * Sleep and retry the operation to the same fileserver.
126 static bool afs_sleep_and_retry(struct afs_fs_cursor
*fc
)
128 msleep_interruptible(1000);
129 if (signal_pending(current
)) {
130 fc
->ac
.error
= -ERESTARTSYS
;
138 * Select the fileserver to use. May be called multiple times to rotate
139 * through the fileservers.
141 bool afs_select_fileserver(struct afs_fs_cursor
*fc
)
143 struct afs_addr_list
*alist
;
144 struct afs_server
*server
;
145 struct afs_vnode
*vnode
= fc
->vnode
;
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
);
152 if (fc
->flags
& AFS_FS_CURSOR_STOP
) {
153 _leave(" = f [stopped]");
157 /* Evaluate the result of the previous operation, if there was one. */
158 switch (fc
->ac
.error
) {
164 /* Success or local failure. Stop. */
165 fc
->flags
|= AFS_FS_CURSOR_STOP
;
166 _leave(" = f [okay/local %d]", fc
->ac
.error
);
170 /* The far side rejected the operation on some grounds. This
171 * might involve the server being busy or the volume having been moved.
173 switch (fc
->ac
.abort_code
) {
175 /* This fileserver doesn't know about the volume.
176 * - May indicate that the VL is wrong - retry once and compare
178 * - May indicate that the fileserver couldn't attach to the vol.
180 if (fc
->flags
& AFS_FS_CURSOR_VNOVOL
) {
181 fc
->ac
.error
= -EREMOTEIO
;
185 write_lock(&vnode
->volume
->servers_lock
);
186 fc
->server_list
->vnovol_mask
|= 1 << fc
->index
;
187 write_unlock(&vnode
->volume
->servers_lock
);
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)
194 if (test_bit(AFS_VOLUME_DELETED
, &vnode
->volume
->flags
)) {
195 fc
->ac
.error
= -ENOMEDIUM
;
199 /* If the server list didn't change, then assume that
200 * it's the fileserver having trouble.
202 if (vnode
->volume
->servers
== fc
->server_list
) {
203 fc
->ac
.error
= -EREMOTEIO
;
208 fc
->flags
|= AFS_FS_CURSOR_VNOVOL
;
209 _leave(" = t [vnovol]");
212 case VSALVAGE
: /* TODO: Should this return an error or iterate? */
218 fc
->ac
.error
= afs_abort_to_error(fc
->ac
.abort_code
);
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
);
226 if (fc
->flags
& AFS_FS_CURSOR_NO_VSLEEP
) {
227 fc
->ac
.error
= -EADV
;
230 if (fc
->flags
& AFS_FS_CURSOR_CUR_ONLY
) {
231 fc
->ac
.error
= -ESTALE
;
239 /* Retry after going round all the servers unless we
240 * have a file lock we need to maintain.
242 if (fc
->flags
& AFS_FS_CURSOR_NO_VSLEEP
) {
243 fc
->ac
.error
= -EBUSY
;
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
);
251 if (fc
->flags
& AFS_FS_CURSOR_CUR_ONLY
) {
252 if (!afs_sleep_and_retry(fc
))
255 /* Retry with same server & address */
256 _leave(" = t [vbusy]");
260 fc
->flags
|= AFS_FS_CURSOR_VBUSY
;
264 /* The volume migrated to another server. We consider
265 * consider all locks and callbacks broken and request
266 * an update from the VLDB.
268 * We also limit the number of VMOVED hops we will
269 * honour, just in case someone sets up a loop.
271 if (fc
->flags
& AFS_FS_CURSOR_VMOVED
) {
272 fc
->ac
.error
= -EREMOTEIO
;
275 fc
->flags
|= AFS_FS_CURSOR_VMOVED
;
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)
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.
288 * TODO: Try other fileservers if we can.
290 * TODO: Retry a few times with sleeps.
292 if (vnode
->volume
->servers
== fc
->server_list
) {
293 fc
->ac
.error
= -ENOMEDIUM
;
297 goto restart_from_beginning
;
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
);
312 goto iterate_address
;
315 restart_from_beginning
:
317 afs_end_cursor(&fc
->ac
);
318 afs_put_cb_interest(afs_v2net(vnode
), fc
->cbi
);
320 afs_put_serverlist(afs_v2net(vnode
), fc
->server_list
);
321 fc
->server_list
= NULL
;
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.
327 fc
->ac
.error
= afs_check_volume_status(vnode
->volume
, fc
->key
);
328 if (fc
->ac
.error
< 0)
331 if (!afs_start_fs_iteration(fc
, vnode
))
337 afs_end_cursor(&fc
->ac
);
338 afs_put_cb_interest(afs_v2net(vnode
), fc
->cbi
);
341 if (fc
->index
>= fc
->server_list
->nr_servers
)
343 if (fc
->index
!= fc
->start
)
346 /* That's all the servers poked to no good effect. Try again if some
349 if (fc
->flags
& AFS_FS_CURSOR_VBUSY
)
350 goto restart_from_beginning
;
352 fc
->ac
.error
= -EDESTADDRREQ
;
357 /* We're starting on a different fileserver from the list. We need to
358 * check it, create a callback intercept, find its address list and
359 * probe its capabilities before we use it.
361 ASSERTCMP(fc
->ac
.alist
, ==, NULL
);
362 server
= fc
->server_list
->servers
[fc
->index
].server
;
364 if (!afs_check_server_record(fc
, server
))
367 _debug("USING SERVER: %pU", &server
->uuid
);
369 /* Make sure we've got a callback interest record for this server. We
370 * have to link it in before we send the request as we can be sent a
371 * break request before we've finished decoding the reply and
372 * installing the vnode.
374 fc
->ac
.error
= afs_register_server_cb_interest(vnode
, fc
->server_list
,
376 if (fc
->ac
.error
< 0)
379 fc
->cbi
= afs_get_cb_interest(vnode
->cb_interest
);
381 read_lock(&server
->fs_lock
);
382 alist
= rcu_dereference_protected(server
->addresses
,
383 lockdep_is_held(&server
->fs_lock
));
384 afs_get_addrlist(alist
);
385 read_unlock(&server
->fs_lock
);
387 memset(&fc
->ac
, 0, sizeof(fc
->ac
));
389 /* Probe the current fileserver if we haven't done so yet. */
390 if (!test_bit(AFS_SERVER_FL_PROBED
, &server
->flags
)) {
391 fc
->ac
.alist
= afs_get_addrlist(alist
);
393 if (!afs_probe_fileserver(fc
)) {
394 switch (fc
->ac
.error
) {
406 fc
->ac
.alist
= alist
;
408 afs_put_addrlist(alist
);
410 fc
->ac
.start
= READ_ONCE(alist
->index
);
411 fc
->ac
.index
= fc
->ac
.start
;
412 goto iterate_address
;
415 ASSERT(fc
->ac
.alist
);
416 _debug("iterate %d/%d", fc
->ac
.index
, fc
->ac
.alist
->nr_addrs
);
417 /* Iterate over the current server's address list to try and find an
418 * address on which it will respond to us.
420 if (!afs_iterate_addresses(&fc
->ac
))
427 fc
->flags
|= AFS_FS_CURSOR_STOP
;
428 afs_end_cursor(&fc
->ac
);
429 _leave(" = f [failed %d]", fc
->ac
.error
);
434 * Select the same fileserver we used for a vnode before and only that
435 * fileserver. We use this when we have a lock on that file, which is backed
436 * only by the fileserver we obtained it from.
438 bool afs_select_current_fileserver(struct afs_fs_cursor
*fc
)
440 struct afs_vnode
*vnode
= fc
->vnode
;
441 struct afs_cb_interest
*cbi
= vnode
->cb_interest
;
442 struct afs_addr_list
*alist
;
446 switch (fc
->ac
.error
) {
449 fc
->ac
.error
= -ESTALE
;
450 fc
->flags
|= AFS_FS_CURSOR_STOP
;
454 fc
->cbi
= afs_get_cb_interest(vnode
->cb_interest
);
456 read_lock(&cbi
->server
->fs_lock
);
457 alist
= rcu_dereference_protected(cbi
->server
->addresses
,
458 lockdep_is_held(&cbi
->server
->fs_lock
));
459 afs_get_addrlist(alist
);
460 read_unlock(&cbi
->server
->fs_lock
);
462 fc
->ac
.error
= -ESTALE
;
463 fc
->flags
|= AFS_FS_CURSOR_STOP
;
467 memset(&fc
->ac
, 0, sizeof(fc
->ac
));
468 fc
->ac
.alist
= alist
;
469 fc
->ac
.start
= READ_ONCE(alist
->index
);
470 fc
->ac
.index
= fc
->ac
.start
;
471 goto iterate_address
;
475 /* Success or local failure. Stop. */
476 fc
->flags
|= AFS_FS_CURSOR_STOP
;
477 _leave(" = f [okay/local %d]", fc
->ac
.error
);
481 fc
->flags
|= AFS_FS_CURSOR_STOP
;
482 _leave(" = f [abort]");
491 goto iterate_address
;
495 /* Iterate over the current server's address list to try and find an
496 * address on which it will respond to us.
498 if (afs_iterate_addresses(&fc
->ac
)) {
503 afs_end_cursor(&fc
->ac
);
508 * Tidy up a filesystem cursor and unlock the vnode.
510 int afs_end_vnode_operation(struct afs_fs_cursor
*fc
)
512 struct afs_net
*net
= afs_v2net(fc
->vnode
);
515 mutex_unlock(&fc
->vnode
->io_lock
);
517 afs_end_cursor(&fc
->ac
);
518 afs_put_cb_interest(net
, fc
->cbi
);
519 afs_put_serverlist(net
, fc
->server_list
);
522 if (ret
== -ECONNABORTED
)
523 afs_abort_to_error(fc
->ac
.abort_code
);
530 * Set a filesystem server cursor for using a specific FS server.
532 int afs_set_fs_cursor(struct afs_fs_cursor
*fc
, struct afs_vnode
*vnode
)
534 afs_init_fs_cursor(fc
, vnode
);
536 read_seqlock_excl(&vnode
->cb_lock
);
537 if (vnode
->cb_interest
) {
538 if (vnode
->cb_interest
->server
->fs_state
== 0)
539 fc
->server
= afs_get_server(vnode
->cb_interest
->server
);
541 fc
->ac
.error
= vnode
->cb_interest
->server
->fs_state
;
543 fc
->ac
.error
= -ESTALE
;
545 read_sequnlock_excl(&vnode
->cb_lock
);
551 * pick a server to use to try accessing this volume
552 * - returns with an elevated usage count on the server chosen
554 bool afs_volume_pick_fileserver(struct afs_fs_cursor
*fc
, struct afs_vnode
*vnode
)
556 struct afs_volume
*volume
= vnode
->volume
;
557 struct afs_server
*server
;
558 int ret
, state
, loop
;
560 _enter("%s", volume
->vlocation
->vldb
.name
);
562 /* stick with the server we're already using if we can */
563 if (vnode
->cb_interest
&& vnode
->cb_interest
->server
->fs_state
== 0) {
564 fc
->server
= afs_get_server(vnode
->cb_interest
->server
);
568 down_read(&volume
->server_sem
);
570 /* handle the no-server case */
571 if (volume
->nservers
== 0) {
572 fc
->ac
.error
= volume
->rjservers
? -ENOMEDIUM
: -ESTALE
;
573 up_read(&volume
->server_sem
);
574 _leave(" = f [no servers %d]", fc
->ac
.error
);
578 /* basically, just search the list for the first live server and use
581 for (loop
= 0; loop
< volume
->nservers
; loop
++) {
582 server
= volume
->servers
[loop
];
583 state
= server
->fs_state
;
585 _debug("consider %d [%d]", loop
, state
);
604 ret
== -ENETUNREACH
||
605 ret
== -EHOSTUNREACH
)
612 ret
== -ENETUNREACH
||
613 ret
== -EHOSTUNREACH
||
614 ret
== -ECONNREFUSED
)
623 /* no available servers
624 * - TODO: handle the no active servers case better
626 up_read(&volume
->server_sem
);
627 _leave(" = f [%d]", fc
->ac
.error
);
631 /* Found an apparently healthy server. We need to register an interest
632 * in receiving callbacks before we talk to it.
634 ret
= afs_register_server_cb_interest(vnode
,
635 &volume
->cb_interests
[loop
], server
);
639 fc
->server
= afs_get_server(server
);
640 up_read(&volume
->server_sem
);
642 fc
->ac
.alist
= afs_get_addrlist(fc
->server
->addrs
);
643 fc
->ac
.addr
= &fc
->ac
.alist
->addrs
[0];
644 _debug("USING SERVER: %pIS\n", &fc
->ac
.addr
->transport
);
645 _leave(" = t (picked %pIS)", &fc
->ac
.addr
->transport
);
650 * release a server after use
651 * - releases the ref on the server struct that was acquired by picking
652 * - records result of using a particular server to access a volume
653 * - return true to try again, false if okay or to issue error
654 * - the caller must release the server struct if result was false
656 bool afs_iterate_fs_cursor(struct afs_fs_cursor
*fc
,
657 struct afs_vnode
*vnode
)
659 struct afs_volume
*volume
= vnode
->volume
;
660 struct afs_server
*server
= fc
->server
;
664 volume
->vlocation
->vldb
.name
, &fc
->ac
.addr
->transport
,
667 switch (fc
->ac
.error
) {
670 server
->fs_state
= 0;
674 /* the fileserver denied all knowledge of the volume */
676 down_write(&volume
->server_sem
);
678 /* firstly, find where the server is in the active list (if it
680 for (loop
= 0; loop
< volume
->nservers
; loop
++)
681 if (volume
->servers
[loop
] == server
)
684 /* no longer there - may have been discarded by another op */
685 goto try_next_server_upw
;
689 memmove(&volume
->servers
[loop
],
690 &volume
->servers
[loop
+ 1],
691 sizeof(volume
->servers
[loop
]) *
692 (volume
->nservers
- loop
));
693 volume
->servers
[volume
->nservers
] = NULL
;
694 afs_put_server(afs_v2net(vnode
), server
);
697 if (volume
->nservers
> 0)
698 /* another server might acknowledge its existence */
699 goto try_next_server_upw
;
701 /* handle the case where all the fileservers have rejected the
703 * - TODO: try asking the fileservers for volume information
704 * - TODO: contact the VL server again to see if the volume is
705 * no longer registered
707 up_write(&volume
->server_sem
);
708 afs_put_server(afs_v2net(vnode
), server
);
710 _leave(" = f [completely rejected]");
713 /* problem reaching the server */
720 /* mark the server as dead
721 * TODO: vary dead timeout depending on error
723 spin_lock(&server
->fs_lock
);
724 if (!server
->fs_state
) {
725 server
->fs_state
= fc
->ac
.error
;
726 printk("kAFS: SERVER DEAD state=%d\n", fc
->ac
.error
);
728 spin_unlock(&server
->fs_lock
);
729 goto try_next_server
;
731 /* miscellaneous error */
735 /* tell the caller to accept the result */
736 afs_put_server(afs_v2net(vnode
), server
);
738 _leave(" = f [local failure]");
742 /* tell the caller to loop around and try the next server */
744 up_write(&volume
->server_sem
);
746 afs_put_server(afs_v2net(vnode
), server
);
747 _leave(" = t [try next server]");
752 * Clean up a fileserver cursor.
754 int afs_end_fs_cursor(struct afs_fs_cursor
*fc
, struct afs_net
*net
)
756 afs_end_cursor(&fc
->ac
);
757 afs_put_server(net
, fc
->server
);