1 /* AFS volume management
2 *
3 * Copyright (C) 2002, 2007 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 License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/fs.h>
17 #include <linux/pagemap.h>
18 #include <linux/sched.h>
19 #include "internal.h"
20
21 static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
22
23 /*
24 * lookup a volume by name
25 * - this can be one of the following:
26 * "%[cell:]volume[.]" R/W volume
27 * "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
28 * or R/W (rwparent=1) volume
29 * "%[cell:]volume.readonly" R/O volume
30 * "#[cell:]volume.readonly" R/O volume
31 * "%[cell:]volume.backup" Backup volume
32 * "#[cell:]volume.backup" Backup volume
33 *
34 * The cell name is optional, and defaults to the current cell.
35 *
36 * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
37 * Guide
38 * - Rule 1: Explicit type suffix forces access of that type or nothing
39 * (no suffix, then use Rule 2 & 3)
40 * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
41 * if not available
42 * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
43 * explicitly told otherwise
44 */
afs_volume_lookup(struct afs_mount_params * params)45 struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
46 {
47 struct afs_vlocation *vlocation = NULL;
48 struct afs_volume *volume = NULL;
49 struct afs_server *server = NULL;
50 char srvtmask;
51 int ret, loop;
52
53 _enter("{%*.*s,%d}",
54 params->volnamesz, params->volnamesz, params->volname, params->rwpath);
55
56 /* lookup the volume location record */
57 vlocation = afs_vlocation_lookup(params->cell, params->key,
58 params->volname, params->volnamesz);
59 if (IS_ERR(vlocation)) {
60 ret = PTR_ERR(vlocation);
61 vlocation = NULL;
62 goto error;
63 }
64
65 /* make the final decision on the type we want */
66 ret = -ENOMEDIUM;
67 if (params->force && !(vlocation->vldb.vidmask & (1 << params->type)))
68 goto error;
69
70 srvtmask = 0;
71 for (loop = 0; loop < vlocation->vldb.nservers; loop++)
72 srvtmask |= vlocation->vldb.srvtmask[loop];
73
74 if (params->force) {
75 if (!(srvtmask & (1 << params->type)))
76 goto error;
77 } else if (srvtmask & AFS_VOL_VTM_RO) {
78 params->type = AFSVL_ROVOL;
79 } else if (srvtmask & AFS_VOL_VTM_RW) {
80 params->type = AFSVL_RWVOL;
81 } else {
82 goto error;
83 }
84
85 down_write(¶ms->cell->vl_sem);
86
87 /* is the volume already active? */
88 if (vlocation->vols[params->type]) {
89 /* yes - re-use it */
90 volume = vlocation->vols[params->type];
91 afs_get_volume(volume);
92 goto success;
93 }
94
95 /* create a new volume record */
96 _debug("creating new volume record");
97
98 ret = -ENOMEM;
99 volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
100 if (!volume)
101 goto error_up;
102
103 atomic_set(&volume->usage, 1);
104 volume->type = params->type;
105 volume->type_force = params->force;
106 volume->cell = params->cell;
107 volume->vid = vlocation->vldb.vid[params->type];
108
109 ret = bdi_setup_and_register(&volume->bdi, "afs", BDI_CAP_MAP_COPY);
110 if (ret)
111 goto error_bdi;
112
113 init_rwsem(&volume->server_sem);
114
115 /* look up all the applicable server records */
116 for (loop = 0; loop < 8; loop++) {
117 if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
118 server = afs_lookup_server(
119 volume->cell, &vlocation->vldb.servers[loop]);
120 if (IS_ERR(server)) {
121 ret = PTR_ERR(server);
122 goto error_discard;
123 }
124
125 volume->servers[volume->nservers] = server;
126 volume->nservers++;
127 }
128 }
129
130 /* attach the cache and volume location */
131 #ifdef CONFIG_AFS_FSCACHE
132 volume->cache = fscache_acquire_cookie(vlocation->cache,
133 &afs_volume_cache_index_def,
134 volume);
135 #endif
136 afs_get_vlocation(vlocation);
137 volume->vlocation = vlocation;
138
139 vlocation->vols[volume->type] = volume;
140
141 success:
142 _debug("kAFS selected %s volume %08x",
143 afs_voltypes[volume->type], volume->vid);
144 up_write(¶ms->cell->vl_sem);
145 afs_put_vlocation(vlocation);
146 _leave(" = %p", volume);
147 return volume;
148
149 /* clean up */
150 error_up:
151 up_write(¶ms->cell->vl_sem);
152 error:
153 afs_put_vlocation(vlocation);
154 _leave(" = %d", ret);
155 return ERR_PTR(ret);
156
157 error_discard:
158 bdi_destroy(&volume->bdi);
159 error_bdi:
160 up_write(¶ms->cell->vl_sem);
161
162 for (loop = volume->nservers - 1; loop >= 0; loop--)
163 afs_put_server(volume->servers[loop]);
164
165 kfree(volume);
166 goto error;
167 }
168
169 /*
170 * destroy a volume record
171 */
afs_put_volume(struct afs_volume * volume)172 void afs_put_volume(struct afs_volume *volume)
173 {
174 struct afs_vlocation *vlocation;
175 int loop;
176
177 if (!volume)
178 return;
179
180 _enter("%p", volume);
181
182 ASSERTCMP(atomic_read(&volume->usage), >, 0);
183
184 vlocation = volume->vlocation;
185
186 /* to prevent a race, the decrement and the dequeue must be effectively
187 * atomic */
188 down_write(&vlocation->cell->vl_sem);
189
190 if (likely(!atomic_dec_and_test(&volume->usage))) {
191 up_write(&vlocation->cell->vl_sem);
192 _leave("");
193 return;
194 }
195
196 vlocation->vols[volume->type] = NULL;
197
198 up_write(&vlocation->cell->vl_sem);
199
200 /* finish cleaning up the volume */
201 #ifdef CONFIG_AFS_FSCACHE
202 fscache_relinquish_cookie(volume->cache, 0);
203 #endif
204 afs_put_vlocation(vlocation);
205
206 for (loop = volume->nservers - 1; loop >= 0; loop--)
207 afs_put_server(volume->servers[loop]);
208
209 bdi_destroy(&volume->bdi);
210 kfree(volume);
211
212 _leave(" [destroyed]");
213 }
214
215 /*
216 * pick a server to use to try accessing this volume
217 * - returns with an elevated usage count on the server chosen
218 */
afs_volume_pick_fileserver(struct afs_vnode * vnode)219 struct afs_server *afs_volume_pick_fileserver(struct afs_vnode *vnode)
220 {
221 struct afs_volume *volume = vnode->volume;
222 struct afs_server *server;
223 int ret, state, loop;
224
225 _enter("%s", volume->vlocation->vldb.name);
226
227 /* stick with the server we're already using if we can */
228 if (vnode->server && vnode->server->fs_state == 0) {
229 afs_get_server(vnode->server);
230 _leave(" = %p [current]", vnode->server);
231 return vnode->server;
232 }
233
234 down_read(&volume->server_sem);
235
236 /* handle the no-server case */
237 if (volume->nservers == 0) {
238 ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
239 up_read(&volume->server_sem);
240 _leave(" = %d [no servers]", ret);
241 return ERR_PTR(ret);
242 }
243
244 /* basically, just search the list for the first live server and use
245 * that */
246 ret = 0;
247 for (loop = 0; loop < volume->nservers; loop++) {
248 server = volume->servers[loop];
249 state = server->fs_state;
250
251 _debug("consider %d [%d]", loop, state);
252
253 switch (state) {
254 /* found an apparently healthy server */
255 case 0:
256 afs_get_server(server);
257 up_read(&volume->server_sem);
258 _leave(" = %p (picked %08x)",
259 server, ntohl(server->addr.s_addr));
260 return server;
261
262 case -ENETUNREACH:
263 if (ret == 0)
264 ret = state;
265 break;
266
267 case -EHOSTUNREACH:
268 if (ret == 0 ||
269 ret == -ENETUNREACH)
270 ret = state;
271 break;
272
273 case -ECONNREFUSED:
274 if (ret == 0 ||
275 ret == -ENETUNREACH ||
276 ret == -EHOSTUNREACH)
277 ret = state;
278 break;
279
280 default:
281 case -EREMOTEIO:
282 if (ret == 0 ||
283 ret == -ENETUNREACH ||
284 ret == -EHOSTUNREACH ||
285 ret == -ECONNREFUSED)
286 ret = state;
287 break;
288 }
289 }
290
291 /* no available servers
292 * - TODO: handle the no active servers case better
293 */
294 up_read(&volume->server_sem);
295 _leave(" = %d", ret);
296 return ERR_PTR(ret);
297 }
298
299 /*
300 * release a server after use
301 * - releases the ref on the server struct that was acquired by picking
302 * - records result of using a particular server to access a volume
303 * - return 0 to try again, 1 if okay or to issue error
304 * - the caller must release the server struct if result was 0
305 */
afs_volume_release_fileserver(struct afs_vnode * vnode,struct afs_server * server,int result)306 int afs_volume_release_fileserver(struct afs_vnode *vnode,
307 struct afs_server *server,
308 int result)
309 {
310 struct afs_volume *volume = vnode->volume;
311 unsigned loop;
312
313 _enter("%s,%08x,%d",
314 volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
315 result);
316
317 switch (result) {
318 /* success */
319 case 0:
320 server->fs_act_jif = jiffies;
321 server->fs_state = 0;
322 _leave("");
323 return 1;
324
325 /* the fileserver denied all knowledge of the volume */
326 case -ENOMEDIUM:
327 server->fs_act_jif = jiffies;
328 down_write(&volume->server_sem);
329
330 /* firstly, find where the server is in the active list (if it
331 * is) */
332 for (loop = 0; loop < volume->nservers; loop++)
333 if (volume->servers[loop] == server)
334 goto present;
335
336 /* no longer there - may have been discarded by another op */
337 goto try_next_server_upw;
338
339 present:
340 volume->nservers--;
341 memmove(&volume->servers[loop],
342 &volume->servers[loop + 1],
343 sizeof(volume->servers[loop]) *
344 (volume->nservers - loop));
345 volume->servers[volume->nservers] = NULL;
346 afs_put_server(server);
347 volume->rjservers++;
348
349 if (volume->nservers > 0)
350 /* another server might acknowledge its existence */
351 goto try_next_server_upw;
352
353 /* handle the case where all the fileservers have rejected the
354 * volume
355 * - TODO: try asking the fileservers for volume information
356 * - TODO: contact the VL server again to see if the volume is
357 * no longer registered
358 */
359 up_write(&volume->server_sem);
360 afs_put_server(server);
361 _leave(" [completely rejected]");
362 return 1;
363
364 /* problem reaching the server */
365 case -ENETUNREACH:
366 case -EHOSTUNREACH:
367 case -ECONNREFUSED:
368 case -ETIME:
369 case -ETIMEDOUT:
370 case -EREMOTEIO:
371 /* mark the server as dead
372 * TODO: vary dead timeout depending on error
373 */
374 spin_lock(&server->fs_lock);
375 if (!server->fs_state) {
376 server->fs_dead_jif = jiffies + HZ * 10;
377 server->fs_state = result;
378 printk("kAFS: SERVER DEAD state=%d\n", result);
379 }
380 spin_unlock(&server->fs_lock);
381 goto try_next_server;
382
383 /* miscellaneous error */
384 default:
385 server->fs_act_jif = jiffies;
386 case -ENOMEM:
387 case -ENONET:
388 /* tell the caller to accept the result */
389 afs_put_server(server);
390 _leave(" [local failure]");
391 return 1;
392 }
393
394 /* tell the caller to loop around and try the next server */
395 try_next_server_upw:
396 up_write(&volume->server_sem);
397 try_next_server:
398 afs_put_server(server);
399 _leave(" [try next server]");
400 return 0;
401 }
402