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1 | /* -*- c -*- --------------------------------------------------------------- * |
2 | * |
3 | * linux/fs/autofs/expire.c |
4 | * |
5 | * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved |
6 | * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org> |
7 | * Copyright 2001-2006 Ian Kent <raven@themaw.net> |
8 | * |
9 | * This file is part of the Linux kernel and is made available under |
10 | * the terms of the GNU General Public License, version 2, or at your |
11 | * option, any later version, incorporated herein by reference. |
12 | * |
13 | * ------------------------------------------------------------------------- */ |
14 | |
15 | #include "autofs_i.h" |
16 | |
17 | static unsigned long now; |
18 | |
19 | /* Check if a dentry can be expired */ |
20 | static inline int autofs4_can_expire(struct dentry *dentry, |
21 | unsigned long timeout, int do_now) |
22 | { |
23 | struct autofs_info *ino = autofs4_dentry_ino(dentry); |
24 | |
25 | /* dentry in the process of being deleted */ |
26 | if (ino == NULL) |
27 | return 0; |
28 | |
29 | /* No point expiring a pending mount */ |
30 | if (ino->flags & AUTOFS_INF_PENDING) |
31 | return 0; |
32 | |
33 | if (!do_now) { |
34 | /* Too young to die */ |
35 | if (!timeout || time_after(ino->last_used + timeout, now)) |
36 | return 0; |
37 | |
38 | /* update last_used here :- |
39 | - obviously makes sense if it is in use now |
40 | - less obviously, prevents rapid-fire expire |
41 | attempts if expire fails the first time */ |
42 | ino->last_used = now; |
43 | } |
44 | return 1; |
45 | } |
46 | |
47 | /* Check a mount point for busyness */ |
48 | static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry) |
49 | { |
50 | struct dentry *top = dentry; |
51 | struct path path = {.mnt = mnt, .dentry = dentry}; |
52 | int status = 1; |
53 | |
54 | DPRINTK("dentry %p %.*s", |
55 | dentry, (int)dentry->d_name.len, dentry->d_name.name); |
56 | |
57 | path_get(&path); |
58 | |
59 | if (!follow_down(&path)) |
60 | goto done; |
61 | |
62 | if (is_autofs4_dentry(path.dentry)) { |
63 | struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb); |
64 | |
65 | /* This is an autofs submount, we can't expire it */ |
66 | if (autofs_type_indirect(sbi->type)) |
67 | goto done; |
68 | |
69 | /* |
70 | * Otherwise it's an offset mount and we need to check |
71 | * if we can umount its mount, if there is one. |
72 | */ |
73 | if (!d_mountpoint(path.dentry)) { |
74 | status = 0; |
75 | goto done; |
76 | } |
77 | } |
78 | |
79 | /* Update the expiry counter if fs is busy */ |
80 | if (!may_umount_tree(path.mnt)) { |
81 | struct autofs_info *ino = autofs4_dentry_ino(top); |
82 | ino->last_used = jiffies; |
83 | goto done; |
84 | } |
85 | |
86 | status = 0; |
87 | done: |
88 | DPRINTK("returning = %d", status); |
89 | path_put(&path); |
90 | return status; |
91 | } |
92 | |
93 | /* |
94 | * Calculate next entry in top down tree traversal. |
95 | * From next_mnt in namespace.c - elegant. |
96 | */ |
97 | static struct dentry *next_dentry(struct dentry *p, struct dentry *root) |
98 | { |
99 | struct list_head *next = p->d_subdirs.next; |
100 | |
101 | if (next == &p->d_subdirs) { |
102 | while (1) { |
103 | if (p == root) |
104 | return NULL; |
105 | next = p->d_u.d_child.next; |
106 | if (next != &p->d_parent->d_subdirs) |
107 | break; |
108 | p = p->d_parent; |
109 | } |
110 | } |
111 | return list_entry(next, struct dentry, d_u.d_child); |
112 | } |
113 | |
114 | /* |
115 | * Check a direct mount point for busyness. |
116 | * Direct mounts have similar expiry semantics to tree mounts. |
117 | * The tree is not busy iff no mountpoints are busy and there are no |
118 | * autofs submounts. |
119 | */ |
120 | static int autofs4_direct_busy(struct vfsmount *mnt, |
121 | struct dentry *top, |
122 | unsigned long timeout, |
123 | int do_now) |
124 | { |
125 | DPRINTK("top %p %.*s", |
126 | top, (int) top->d_name.len, top->d_name.name); |
127 | |
128 | /* If it's busy update the expiry counters */ |
129 | if (!may_umount_tree(mnt)) { |
130 | struct autofs_info *ino = autofs4_dentry_ino(top); |
131 | if (ino) |
132 | ino->last_used = jiffies; |
133 | return 1; |
134 | } |
135 | |
136 | /* Timeout of a direct mount is determined by its top dentry */ |
137 | if (!autofs4_can_expire(top, timeout, do_now)) |
138 | return 1; |
139 | |
140 | return 0; |
141 | } |
142 | |
143 | /* Check a directory tree of mount points for busyness |
144 | * The tree is not busy iff no mountpoints are busy |
145 | */ |
146 | static int autofs4_tree_busy(struct vfsmount *mnt, |
147 | struct dentry *top, |
148 | unsigned long timeout, |
149 | int do_now) |
150 | { |
151 | struct autofs_info *top_ino = autofs4_dentry_ino(top); |
152 | struct dentry *p; |
153 | |
154 | DPRINTK("top %p %.*s", |
155 | top, (int)top->d_name.len, top->d_name.name); |
156 | |
157 | /* Negative dentry - give up */ |
158 | if (!simple_positive(top)) |
159 | return 1; |
160 | |
161 | spin_lock(&dcache_lock); |
162 | for (p = top; p; p = next_dentry(p, top)) { |
163 | /* Negative dentry - give up */ |
164 | if (!simple_positive(p)) |
165 | continue; |
166 | |
167 | DPRINTK("dentry %p %.*s", |
168 | p, (int) p->d_name.len, p->d_name.name); |
169 | |
170 | p = dget(p); |
171 | spin_unlock(&dcache_lock); |
172 | |
173 | /* |
174 | * Is someone visiting anywhere in the subtree ? |
175 | * If there's no mount we need to check the usage |
176 | * count for the autofs dentry. |
177 | * If the fs is busy update the expiry counter. |
178 | */ |
179 | if (d_mountpoint(p)) { |
180 | if (autofs4_mount_busy(mnt, p)) { |
181 | top_ino->last_used = jiffies; |
182 | dput(p); |
183 | return 1; |
184 | } |
185 | } else { |
186 | struct autofs_info *ino = autofs4_dentry_ino(p); |
187 | unsigned int ino_count = atomic_read(&ino->count); |
188 | |
189 | /* |
190 | * Clean stale dentries below that have not been |
191 | * invalidated after a mount fail during lookup |
192 | */ |
193 | d_invalidate(p); |
194 | |
195 | /* allow for dget above and top is already dgot */ |
196 | if (p == top) |
197 | ino_count += 2; |
198 | else |
199 | ino_count++; |
200 | |
201 | if (atomic_read(&p->d_count) > ino_count) { |
202 | top_ino->last_used = jiffies; |
203 | dput(p); |
204 | return 1; |
205 | } |
206 | } |
207 | dput(p); |
208 | spin_lock(&dcache_lock); |
209 | } |
210 | spin_unlock(&dcache_lock); |
211 | |
212 | /* Timeout of a tree mount is ultimately determined by its top dentry */ |
213 | if (!autofs4_can_expire(top, timeout, do_now)) |
214 | return 1; |
215 | |
216 | return 0; |
217 | } |
218 | |
219 | static struct dentry *autofs4_check_leaves(struct vfsmount *mnt, |
220 | struct dentry *parent, |
221 | unsigned long timeout, |
222 | int do_now) |
223 | { |
224 | struct dentry *p; |
225 | |
226 | DPRINTK("parent %p %.*s", |
227 | parent, (int)parent->d_name.len, parent->d_name.name); |
228 | |
229 | spin_lock(&dcache_lock); |
230 | for (p = parent; p; p = next_dentry(p, parent)) { |
231 | /* Negative dentry - give up */ |
232 | if (!simple_positive(p)) |
233 | continue; |
234 | |
235 | DPRINTK("dentry %p %.*s", |
236 | p, (int) p->d_name.len, p->d_name.name); |
237 | |
238 | p = dget(p); |
239 | spin_unlock(&dcache_lock); |
240 | |
241 | if (d_mountpoint(p)) { |
242 | /* Can we umount this guy */ |
243 | if (autofs4_mount_busy(mnt, p)) |
244 | goto cont; |
245 | |
246 | /* Can we expire this guy */ |
247 | if (autofs4_can_expire(p, timeout, do_now)) |
248 | return p; |
249 | } |
250 | cont: |
251 | dput(p); |
252 | spin_lock(&dcache_lock); |
253 | } |
254 | spin_unlock(&dcache_lock); |
255 | return NULL; |
256 | } |
257 | |
258 | /* Check if we can expire a direct mount (possibly a tree) */ |
259 | struct dentry *autofs4_expire_direct(struct super_block *sb, |
260 | struct vfsmount *mnt, |
261 | struct autofs_sb_info *sbi, |
262 | int how) |
263 | { |
264 | unsigned long timeout; |
265 | struct dentry *root = dget(sb->s_root); |
266 | int do_now = how & AUTOFS_EXP_IMMEDIATE; |
267 | |
268 | if (!root) |
269 | return NULL; |
270 | |
271 | now = jiffies; |
272 | timeout = sbi->exp_timeout; |
273 | |
274 | spin_lock(&sbi->fs_lock); |
275 | if (!autofs4_direct_busy(mnt, root, timeout, do_now)) { |
276 | struct autofs_info *ino = autofs4_dentry_ino(root); |
277 | if (d_mountpoint(root)) { |
278 | ino->flags |= AUTOFS_INF_MOUNTPOINT; |
279 | root->d_mounted--; |
280 | } |
281 | ino->flags |= AUTOFS_INF_EXPIRING; |
282 | init_completion(&ino->expire_complete); |
283 | spin_unlock(&sbi->fs_lock); |
284 | return root; |
285 | } |
286 | spin_unlock(&sbi->fs_lock); |
287 | dput(root); |
288 | |
289 | return NULL; |
290 | } |
291 | |
292 | /* |
293 | * Find an eligible tree to time-out |
294 | * A tree is eligible if :- |
295 | * - it is unused by any user process |
296 | * - it has been unused for exp_timeout time |
297 | */ |
298 | struct dentry *autofs4_expire_indirect(struct super_block *sb, |
299 | struct vfsmount *mnt, |
300 | struct autofs_sb_info *sbi, |
301 | int how) |
302 | { |
303 | unsigned long timeout; |
304 | struct dentry *root = sb->s_root; |
305 | struct dentry *expired = NULL; |
306 | struct list_head *next; |
307 | int do_now = how & AUTOFS_EXP_IMMEDIATE; |
308 | int exp_leaves = how & AUTOFS_EXP_LEAVES; |
309 | struct autofs_info *ino; |
310 | unsigned int ino_count; |
311 | |
312 | if (!root) |
313 | return NULL; |
314 | |
315 | now = jiffies; |
316 | timeout = sbi->exp_timeout; |
317 | |
318 | spin_lock(&dcache_lock); |
319 | next = root->d_subdirs.next; |
320 | |
321 | /* On exit from the loop expire is set to a dgot dentry |
322 | * to expire or it's NULL */ |
323 | while ( next != &root->d_subdirs ) { |
324 | struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child); |
325 | |
326 | /* Negative dentry - give up */ |
327 | if (!simple_positive(dentry)) { |
328 | next = next->next; |
329 | continue; |
330 | } |
331 | |
332 | dentry = dget(dentry); |
333 | spin_unlock(&dcache_lock); |
334 | |
335 | spin_lock(&sbi->fs_lock); |
336 | ino = autofs4_dentry_ino(dentry); |
337 | |
338 | /* |
339 | * Case 1: (i) indirect mount or top level pseudo direct mount |
340 | * (autofs-4.1). |
341 | * (ii) indirect mount with offset mount, check the "/" |
342 | * offset (autofs-5.0+). |
343 | */ |
344 | if (d_mountpoint(dentry)) { |
345 | DPRINTK("checking mountpoint %p %.*s", |
346 | dentry, (int)dentry->d_name.len, dentry->d_name.name); |
347 | |
348 | /* Path walk currently on this dentry? */ |
349 | ino_count = atomic_read(&ino->count) + 2; |
350 | if (atomic_read(&dentry->d_count) > ino_count) |
351 | goto next; |
352 | |
353 | /* Can we umount this guy */ |
354 | if (autofs4_mount_busy(mnt, dentry)) |
355 | goto next; |
356 | |
357 | /* Can we expire this guy */ |
358 | if (autofs4_can_expire(dentry, timeout, do_now)) { |
359 | expired = dentry; |
360 | goto found; |
361 | } |
362 | goto next; |
363 | } |
364 | |
365 | if (simple_empty(dentry)) |
366 | goto next; |
367 | |
368 | /* Case 2: tree mount, expire iff entire tree is not busy */ |
369 | if (!exp_leaves) { |
370 | /* Path walk currently on this dentry? */ |
371 | ino_count = atomic_read(&ino->count) + 1; |
372 | if (atomic_read(&dentry->d_count) > ino_count) |
373 | goto next; |
374 | |
375 | if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) { |
376 | expired = dentry; |
377 | goto found; |
378 | } |
379 | /* |
380 | * Case 3: pseudo direct mount, expire individual leaves |
381 | * (autofs-4.1). |
382 | */ |
383 | } else { |
384 | /* Path walk currently on this dentry? */ |
385 | ino_count = atomic_read(&ino->count) + 1; |
386 | if (atomic_read(&dentry->d_count) > ino_count) |
387 | goto next; |
388 | |
389 | expired = autofs4_check_leaves(mnt, dentry, timeout, do_now); |
390 | if (expired) { |
391 | dput(dentry); |
392 | goto found; |
393 | } |
394 | } |
395 | next: |
396 | spin_unlock(&sbi->fs_lock); |
397 | dput(dentry); |
398 | spin_lock(&dcache_lock); |
399 | next = next->next; |
400 | } |
401 | spin_unlock(&dcache_lock); |
402 | return NULL; |
403 | |
404 | found: |
405 | DPRINTK("returning %p %.*s", |
406 | expired, (int)expired->d_name.len, expired->d_name.name); |
407 | ino = autofs4_dentry_ino(expired); |
408 | ino->flags |= AUTOFS_INF_EXPIRING; |
409 | init_completion(&ino->expire_complete); |
410 | spin_unlock(&sbi->fs_lock); |
411 | spin_lock(&dcache_lock); |
412 | list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child); |
413 | spin_unlock(&dcache_lock); |
414 | return expired; |
415 | } |
416 | |
417 | int autofs4_expire_wait(struct dentry *dentry) |
418 | { |
419 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); |
420 | struct autofs_info *ino = autofs4_dentry_ino(dentry); |
421 | int status; |
422 | |
423 | /* Block on any pending expire */ |
424 | spin_lock(&sbi->fs_lock); |
425 | if (ino->flags & AUTOFS_INF_EXPIRING) { |
426 | spin_unlock(&sbi->fs_lock); |
427 | |
428 | DPRINTK("waiting for expire %p name=%.*s", |
429 | dentry, dentry->d_name.len, dentry->d_name.name); |
430 | |
431 | status = autofs4_wait(sbi, dentry, NFY_NONE); |
432 | wait_for_completion(&ino->expire_complete); |
433 | |
434 | DPRINTK("expire done status=%d", status); |
435 | |
436 | if (d_unhashed(dentry)) |
437 | return -EAGAIN; |
438 | |
439 | return status; |
440 | } |
441 | spin_unlock(&sbi->fs_lock); |
442 | |
443 | return 0; |
444 | } |
445 | |
446 | /* Perform an expiry operation */ |
447 | int autofs4_expire_run(struct super_block *sb, |
448 | struct vfsmount *mnt, |
449 | struct autofs_sb_info *sbi, |
450 | struct autofs_packet_expire __user *pkt_p) |
451 | { |
452 | struct autofs_packet_expire pkt; |
453 | struct autofs_info *ino; |
454 | struct dentry *dentry; |
455 | int ret = 0; |
456 | |
457 | memset(&pkt,0,sizeof pkt); |
458 | |
459 | pkt.hdr.proto_version = sbi->version; |
460 | pkt.hdr.type = autofs_ptype_expire; |
461 | |
462 | if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL) |
463 | return -EAGAIN; |
464 | |
465 | pkt.len = dentry->d_name.len; |
466 | memcpy(pkt.name, dentry->d_name.name, pkt.len); |
467 | pkt.name[pkt.len] = '\0'; |
468 | dput(dentry); |
469 | |
470 | if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) ) |
471 | ret = -EFAULT; |
472 | |
473 | spin_lock(&sbi->fs_lock); |
474 | ino = autofs4_dentry_ino(dentry); |
475 | ino->flags &= ~AUTOFS_INF_EXPIRING; |
476 | complete_all(&ino->expire_complete); |
477 | spin_unlock(&sbi->fs_lock); |
478 | |
479 | return ret; |
480 | } |
481 | |
482 | int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt, |
483 | struct autofs_sb_info *sbi, int when) |
484 | { |
485 | struct dentry *dentry; |
486 | int ret = -EAGAIN; |
487 | |
488 | if (autofs_type_trigger(sbi->type)) |
489 | dentry = autofs4_expire_direct(sb, mnt, sbi, when); |
490 | else |
491 | dentry = autofs4_expire_indirect(sb, mnt, sbi, when); |
492 | |
493 | if (dentry) { |
494 | struct autofs_info *ino = autofs4_dentry_ino(dentry); |
495 | |
496 | /* This is synchronous because it makes the daemon a |
497 | little easier */ |
498 | ret = autofs4_wait(sbi, dentry, NFY_EXPIRE); |
499 | |
500 | spin_lock(&sbi->fs_lock); |
501 | if (ino->flags & AUTOFS_INF_MOUNTPOINT) { |
502 | sb->s_root->d_mounted++; |
503 | ino->flags &= ~AUTOFS_INF_MOUNTPOINT; |
504 | } |
505 | ino->flags &= ~AUTOFS_INF_EXPIRING; |
506 | complete_all(&ino->expire_complete); |
507 | spin_unlock(&sbi->fs_lock); |
508 | dput(dentry); |
509 | } |
510 | |
511 | return ret; |
512 | } |
513 | |
514 | /* Call repeatedly until it returns -EAGAIN, meaning there's nothing |
515 | more to be done */ |
516 | int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt, |
517 | struct autofs_sb_info *sbi, int __user *arg) |
518 | { |
519 | int do_now = 0; |
520 | |
521 | if (arg && get_user(do_now, arg)) |
522 | return -EFAULT; |
523 | |
524 | return autofs4_do_expire_multi(sb, mnt, sbi, do_now); |
525 | } |
526 | |
527 |
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