Commit | Line | Data |
---|---|---|
1da177e4 LT |
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> | |
3a15e2ab | 7 | * Copyright 2001-2006 Ian Kent <raven@themaw.net> |
1da177e4 LT |
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 | ||
1f5f2c30 | 19 | /* Check if a dentry can be expired */ |
1da177e4 LT |
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 (dentry->d_flags & DCACHE_AUTOFS_PENDING) | |
31 | return 0; | |
32 | ||
33 | if (!do_now) { | |
34 | /* Too young to die */ | |
35 | if (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 | } | |
1da177e4 LT |
44 | return 1; |
45 | } | |
46 | ||
1f5f2c30 IK |
47 | /* Check a mount point for busyness */ |
48 | static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry) | |
1da177e4 | 49 | { |
e0a7aae9 | 50 | struct dentry *top = dentry; |
1f5f2c30 | 51 | int status = 1; |
1da177e4 LT |
52 | |
53 | DPRINTK("dentry %p %.*s", | |
54 | dentry, (int)dentry->d_name.len, dentry->d_name.name); | |
55 | ||
56 | mntget(mnt); | |
57 | dget(dentry); | |
58 | ||
9b1e3afd | 59 | if (!autofs4_follow_mount(&mnt, &dentry)) |
1da177e4 LT |
60 | goto done; |
61 | ||
1da177e4 LT |
62 | /* This is an autofs submount, we can't expire it */ |
63 | if (is_autofs4_dentry(dentry)) | |
64 | goto done; | |
65 | ||
e0a7aae9 | 66 | /* Update the expiry counter if fs is busy */ |
e3474a8e | 67 | if (!may_umount_tree(mnt)) { |
e0a7aae9 IK |
68 | struct autofs_info *ino = autofs4_dentry_ino(top); |
69 | ino->last_used = jiffies; | |
70 | goto done; | |
71 | } | |
72 | ||
73 | status = 0; | |
1da177e4 LT |
74 | done: |
75 | DPRINTK("returning = %d", status); | |
76 | mntput(mnt); | |
77 | dput(dentry); | |
78 | return status; | |
79 | } | |
80 | ||
1ce12bad IK |
81 | /* |
82 | * Calculate next entry in top down tree traversal. | |
83 | * From next_mnt in namespace.c - elegant. | |
84 | */ | |
85 | static struct dentry *next_dentry(struct dentry *p, struct dentry *root) | |
86 | { | |
87 | struct list_head *next = p->d_subdirs.next; | |
88 | ||
89 | if (next == &p->d_subdirs) { | |
90 | while (1) { | |
91 | if (p == root) | |
92 | return NULL; | |
93 | next = p->d_u.d_child.next; | |
94 | if (next != &p->d_parent->d_subdirs) | |
95 | break; | |
96 | p = p->d_parent; | |
97 | } | |
98 | } | |
99 | return list_entry(next, struct dentry, d_u.d_child); | |
100 | } | |
101 | ||
3a15e2ab IK |
102 | /* |
103 | * Check a direct mount point for busyness. | |
104 | * Direct mounts have similar expiry semantics to tree mounts. | |
105 | * The tree is not busy iff no mountpoints are busy and there are no | |
106 | * autofs submounts. | |
107 | */ | |
108 | static int autofs4_direct_busy(struct vfsmount *mnt, | |
109 | struct dentry *top, | |
110 | unsigned long timeout, | |
111 | int do_now) | |
112 | { | |
113 | DPRINTK("top %p %.*s", | |
114 | top, (int) top->d_name.len, top->d_name.name); | |
115 | ||
3a15e2ab IK |
116 | /* If it's busy update the expiry counters */ |
117 | if (!may_umount_tree(mnt)) { | |
118 | struct autofs_info *ino = autofs4_dentry_ino(top); | |
119 | if (ino) | |
120 | ino->last_used = jiffies; | |
121 | return 1; | |
122 | } | |
123 | ||
124 | /* Timeout of a direct mount is determined by its top dentry */ | |
125 | if (!autofs4_can_expire(top, timeout, do_now)) | |
126 | return 1; | |
127 | ||
128 | return 0; | |
129 | } | |
130 | ||
1da177e4 LT |
131 | /* Check a directory tree of mount points for busyness |
132 | * The tree is not busy iff no mountpoints are busy | |
1da177e4 | 133 | */ |
1f5f2c30 IK |
134 | static int autofs4_tree_busy(struct vfsmount *mnt, |
135 | struct dentry *top, | |
136 | unsigned long timeout, | |
137 | int do_now) | |
1da177e4 | 138 | { |
e0a7aae9 | 139 | struct autofs_info *top_ino = autofs4_dentry_ino(top); |
1ce12bad | 140 | struct dentry *p; |
1da177e4 | 141 | |
1f5f2c30 | 142 | DPRINTK("top %p %.*s", |
1da177e4 LT |
143 | top, (int)top->d_name.len, top->d_name.name); |
144 | ||
145 | /* Negative dentry - give up */ | |
146 | if (!simple_positive(top)) | |
1f5f2c30 | 147 | return 1; |
1da177e4 | 148 | |
1da177e4 | 149 | spin_lock(&dcache_lock); |
1ce12bad | 150 | for (p = top; p; p = next_dentry(p, top)) { |
1da177e4 | 151 | /* Negative dentry - give up */ |
1ce12bad | 152 | if (!simple_positive(p)) |
1da177e4 | 153 | continue; |
1da177e4 LT |
154 | |
155 | DPRINTK("dentry %p %.*s", | |
1ce12bad | 156 | p, (int) p->d_name.len, p->d_name.name); |
1da177e4 | 157 | |
1ce12bad | 158 | p = dget(p); |
1da177e4 LT |
159 | spin_unlock(&dcache_lock); |
160 | ||
1aff3c8b IK |
161 | /* |
162 | * Is someone visiting anywhere in the subtree ? | |
163 | * If there's no mount we need to check the usage | |
164 | * count for the autofs dentry. | |
e0a7aae9 | 165 | * If the fs is busy update the expiry counter. |
1aff3c8b | 166 | */ |
1ce12bad | 167 | if (d_mountpoint(p)) { |
1ce12bad | 168 | if (autofs4_mount_busy(mnt, p)) { |
e0a7aae9 | 169 | top_ino->last_used = jiffies; |
1ce12bad | 170 | dput(p); |
1f5f2c30 | 171 | return 1; |
1da177e4 | 172 | } |
1aff3c8b | 173 | } else { |
e0a7aae9 | 174 | struct autofs_info *ino = autofs4_dentry_ino(p); |
1aff3c8b IK |
175 | unsigned int ino_count = atomic_read(&ino->count); |
176 | ||
177 | /* allow for dget above and top is already dgot */ | |
178 | if (p == top) | |
179 | ino_count += 2; | |
180 | else | |
181 | ino_count++; | |
182 | ||
183 | if (atomic_read(&p->d_count) > ino_count) { | |
e0a7aae9 | 184 | top_ino->last_used = jiffies; |
1aff3c8b IK |
185 | dput(p); |
186 | return 1; | |
187 | } | |
1da177e4 | 188 | } |
1ce12bad | 189 | dput(p); |
1da177e4 | 190 | spin_lock(&dcache_lock); |
1da177e4 LT |
191 | } |
192 | spin_unlock(&dcache_lock); | |
1aff3c8b IK |
193 | |
194 | /* Timeout of a tree mount is ultimately determined by its top dentry */ | |
195 | if (!autofs4_can_expire(top, timeout, do_now)) | |
196 | return 1; | |
197 | ||
1f5f2c30 | 198 | return 0; |
1da177e4 LT |
199 | } |
200 | ||
201 | static struct dentry *autofs4_check_leaves(struct vfsmount *mnt, | |
202 | struct dentry *parent, | |
203 | unsigned long timeout, | |
204 | int do_now) | |
205 | { | |
1ce12bad | 206 | struct dentry *p; |
1da177e4 LT |
207 | |
208 | DPRINTK("parent %p %.*s", | |
209 | parent, (int)parent->d_name.len, parent->d_name.name); | |
210 | ||
211 | spin_lock(&dcache_lock); | |
1ce12bad | 212 | for (p = parent; p; p = next_dentry(p, parent)) { |
1da177e4 | 213 | /* Negative dentry - give up */ |
1ce12bad | 214 | if (!simple_positive(p)) |
1da177e4 | 215 | continue; |
1da177e4 LT |
216 | |
217 | DPRINTK("dentry %p %.*s", | |
1ce12bad | 218 | p, (int) p->d_name.len, p->d_name.name); |
1da177e4 | 219 | |
1ce12bad | 220 | p = dget(p); |
1da177e4 LT |
221 | spin_unlock(&dcache_lock); |
222 | ||
1ce12bad | 223 | if (d_mountpoint(p)) { |
e0a7aae9 IK |
224 | /* Can we umount this guy */ |
225 | if (autofs4_mount_busy(mnt, p)) | |
1da177e4 LT |
226 | goto cont; |
227 | ||
e0a7aae9 IK |
228 | /* Can we expire this guy */ |
229 | if (autofs4_can_expire(p, timeout, do_now)) | |
1ce12bad | 230 | return p; |
1da177e4 LT |
231 | } |
232 | cont: | |
1ce12bad | 233 | dput(p); |
1da177e4 | 234 | spin_lock(&dcache_lock); |
1da177e4 LT |
235 | } |
236 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
237 | return NULL; |
238 | } | |
239 | ||
3a15e2ab IK |
240 | /* Check if we can expire a direct mount (possibly a tree) */ |
241 | static struct dentry *autofs4_expire_direct(struct super_block *sb, | |
242 | struct vfsmount *mnt, | |
243 | struct autofs_sb_info *sbi, | |
244 | int how) | |
245 | { | |
246 | unsigned long timeout; | |
247 | struct dentry *root = dget(sb->s_root); | |
248 | int do_now = how & AUTOFS_EXP_IMMEDIATE; | |
249 | ||
250 | if (!sbi->exp_timeout || !root) | |
251 | return NULL; | |
252 | ||
253 | now = jiffies; | |
254 | timeout = sbi->exp_timeout; | |
255 | ||
256 | /* Lock the tree as we must expire as a whole */ | |
257 | spin_lock(&sbi->fs_lock); | |
258 | if (!autofs4_direct_busy(mnt, root, timeout, do_now)) { | |
259 | struct autofs_info *ino = autofs4_dentry_ino(root); | |
260 | ||
261 | /* Set this flag early to catch sys_chdir and the like */ | |
262 | ino->flags |= AUTOFS_INF_EXPIRING; | |
263 | spin_unlock(&sbi->fs_lock); | |
264 | return root; | |
265 | } | |
266 | spin_unlock(&sbi->fs_lock); | |
267 | dput(root); | |
268 | ||
269 | return NULL; | |
270 | } | |
271 | ||
1da177e4 LT |
272 | /* |
273 | * Find an eligible tree to time-out | |
274 | * A tree is eligible if :- | |
275 | * - it is unused by any user process | |
276 | * - it has been unused for exp_timeout time | |
277 | */ | |
3a15e2ab IK |
278 | static struct dentry *autofs4_expire_indirect(struct super_block *sb, |
279 | struct vfsmount *mnt, | |
280 | struct autofs_sb_info *sbi, | |
281 | int how) | |
1da177e4 LT |
282 | { |
283 | unsigned long timeout; | |
284 | struct dentry *root = sb->s_root; | |
285 | struct dentry *expired = NULL; | |
286 | struct list_head *next; | |
287 | int do_now = how & AUTOFS_EXP_IMMEDIATE; | |
288 | int exp_leaves = how & AUTOFS_EXP_LEAVES; | |
289 | ||
290 | if ( !sbi->exp_timeout || !root ) | |
291 | return NULL; | |
292 | ||
293 | now = jiffies; | |
294 | timeout = sbi->exp_timeout; | |
295 | ||
296 | spin_lock(&dcache_lock); | |
297 | next = root->d_subdirs.next; | |
298 | ||
299 | /* On exit from the loop expire is set to a dgot dentry | |
300 | * to expire or it's NULL */ | |
301 | while ( next != &root->d_subdirs ) { | |
5160ee6f | 302 | struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child); |
1da177e4 LT |
303 | |
304 | /* Negative dentry - give up */ | |
1f5f2c30 | 305 | if (!simple_positive(dentry)) { |
1da177e4 LT |
306 | next = next->next; |
307 | continue; | |
308 | } | |
309 | ||
310 | dentry = dget(dentry); | |
311 | spin_unlock(&dcache_lock); | |
312 | ||
3a15e2ab IK |
313 | /* |
314 | * Case 1: (i) indirect mount or top level pseudo direct mount | |
315 | * (autofs-4.1). | |
316 | * (ii) indirect mount with offset mount, check the "/" | |
317 | * offset (autofs-5.0+). | |
318 | */ | |
1da177e4 LT |
319 | if (d_mountpoint(dentry)) { |
320 | DPRINTK("checking mountpoint %p %.*s", | |
321 | dentry, (int)dentry->d_name.len, dentry->d_name.name); | |
322 | ||
e0a7aae9 IK |
323 | /* Can we umount this guy */ |
324 | if (autofs4_mount_busy(mnt, dentry)) | |
1da177e4 LT |
325 | goto next; |
326 | ||
e0a7aae9 IK |
327 | /* Can we expire this guy */ |
328 | if (autofs4_can_expire(dentry, timeout, do_now)) { | |
1da177e4 LT |
329 | expired = dentry; |
330 | break; | |
331 | } | |
332 | goto next; | |
333 | } | |
334 | ||
1f5f2c30 | 335 | if (simple_empty(dentry)) |
1da177e4 LT |
336 | goto next; |
337 | ||
338 | /* Case 2: tree mount, expire iff entire tree is not busy */ | |
339 | if (!exp_leaves) { | |
3a9720ce IK |
340 | /* Lock the tree as we must expire as a whole */ |
341 | spin_lock(&sbi->fs_lock); | |
1f5f2c30 | 342 | if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) { |
3a9720ce IK |
343 | struct autofs_info *inf = autofs4_dentry_ino(dentry); |
344 | ||
345 | /* Set this flag early to catch sys_chdir and the like */ | |
346 | inf->flags |= AUTOFS_INF_EXPIRING; | |
347 | spin_unlock(&sbi->fs_lock); | |
348 | expired = dentry; | |
349 | break; | |
1da177e4 | 350 | } |
3a9720ce | 351 | spin_unlock(&sbi->fs_lock); |
3a15e2ab IK |
352 | /* |
353 | * Case 3: pseudo direct mount, expire individual leaves | |
354 | * (autofs-4.1). | |
355 | */ | |
1da177e4 LT |
356 | } else { |
357 | expired = autofs4_check_leaves(mnt, dentry, timeout, do_now); | |
358 | if (expired) { | |
359 | dput(dentry); | |
360 | break; | |
361 | } | |
362 | } | |
363 | next: | |
364 | dput(dentry); | |
365 | spin_lock(&dcache_lock); | |
366 | next = next->next; | |
367 | } | |
368 | ||
1f5f2c30 | 369 | if (expired) { |
1da177e4 LT |
370 | DPRINTK("returning %p %.*s", |
371 | expired, (int)expired->d_name.len, expired->d_name.name); | |
372 | spin_lock(&dcache_lock); | |
373 | list_del(&expired->d_parent->d_subdirs); | |
5160ee6f | 374 | list_add(&expired->d_parent->d_subdirs, &expired->d_u.d_child); |
1da177e4 LT |
375 | spin_unlock(&dcache_lock); |
376 | return expired; | |
377 | } | |
378 | spin_unlock(&dcache_lock); | |
379 | ||
380 | return NULL; | |
381 | } | |
382 | ||
383 | /* Perform an expiry operation */ | |
384 | int autofs4_expire_run(struct super_block *sb, | |
385 | struct vfsmount *mnt, | |
386 | struct autofs_sb_info *sbi, | |
387 | struct autofs_packet_expire __user *pkt_p) | |
388 | { | |
389 | struct autofs_packet_expire pkt; | |
390 | struct dentry *dentry; | |
391 | ||
392 | memset(&pkt,0,sizeof pkt); | |
393 | ||
394 | pkt.hdr.proto_version = sbi->version; | |
395 | pkt.hdr.type = autofs_ptype_expire; | |
396 | ||
3a15e2ab | 397 | if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL) |
1da177e4 LT |
398 | return -EAGAIN; |
399 | ||
400 | pkt.len = dentry->d_name.len; | |
401 | memcpy(pkt.name, dentry->d_name.name, pkt.len); | |
402 | pkt.name[pkt.len] = '\0'; | |
403 | dput(dentry); | |
404 | ||
405 | if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) ) | |
406 | return -EFAULT; | |
407 | ||
408 | return 0; | |
409 | } | |
410 | ||
411 | /* Call repeatedly until it returns -EAGAIN, meaning there's nothing | |
412 | more to be done */ | |
413 | int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt, | |
414 | struct autofs_sb_info *sbi, int __user *arg) | |
415 | { | |
416 | struct dentry *dentry; | |
417 | int ret = -EAGAIN; | |
418 | int do_now = 0; | |
419 | ||
420 | if (arg && get_user(do_now, arg)) | |
421 | return -EFAULT; | |
422 | ||
44d53eb0 | 423 | if (sbi->type & AUTOFS_TYPE_DIRECT) |
3a15e2ab IK |
424 | dentry = autofs4_expire_direct(sb, mnt, sbi, do_now); |
425 | else | |
426 | dentry = autofs4_expire_indirect(sb, mnt, sbi, do_now); | |
427 | ||
428 | if (dentry) { | |
1f5f2c30 | 429 | struct autofs_info *ino = autofs4_dentry_ino(dentry); |
1da177e4 LT |
430 | |
431 | /* This is synchronous because it makes the daemon a | |
432 | little easier */ | |
1f5f2c30 | 433 | ino->flags |= AUTOFS_INF_EXPIRING; |
1da177e4 | 434 | ret = autofs4_wait(sbi, dentry, NFY_EXPIRE); |
1f5f2c30 | 435 | ino->flags &= ~AUTOFS_INF_EXPIRING; |
1da177e4 LT |
436 | dput(dentry); |
437 | } | |
1f5f2c30 | 438 | |
1da177e4 LT |
439 | return ret; |
440 | } | |
441 |