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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> | |
7 | * Copyright 2001-2003 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 return 1 if it can else return 0 */ | |
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 | } | |
44 | ||
45 | return 1; | |
46 | } | |
47 | ||
48 | /* Check a mount point for busyness return 1 if not busy, otherwise */ | |
49 | static int autofs4_check_mount(struct vfsmount *mnt, struct dentry *dentry) | |
50 | { | |
51 | int status = 0; | |
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 | ||
59 | if (!follow_down(&mnt, &dentry)) | |
60 | goto done; | |
61 | ||
62 | while (d_mountpoint(dentry) && follow_down(&mnt, &dentry)) | |
63 | ; | |
64 | ||
65 | /* This is an autofs submount, we can't expire it */ | |
66 | if (is_autofs4_dentry(dentry)) | |
67 | goto done; | |
68 | ||
69 | /* The big question */ | |
70 | if (may_umount_tree(mnt) == 0) | |
71 | status = 1; | |
72 | done: | |
73 | DPRINTK("returning = %d", status); | |
74 | mntput(mnt); | |
75 | dput(dentry); | |
76 | return status; | |
77 | } | |
78 | ||
79 | /* Check a directory tree of mount points for busyness | |
80 | * The tree is not busy iff no mountpoints are busy | |
81 | * Return 1 if the tree is busy or 0 otherwise | |
82 | */ | |
83 | static int autofs4_check_tree(struct vfsmount *mnt, | |
84 | struct dentry *top, | |
85 | unsigned long timeout, | |
86 | int do_now) | |
87 | { | |
88 | struct dentry *this_parent = top; | |
89 | struct list_head *next; | |
90 | ||
91 | DPRINTK("parent %p %.*s", | |
92 | top, (int)top->d_name.len, top->d_name.name); | |
93 | ||
94 | /* Negative dentry - give up */ | |
95 | if (!simple_positive(top)) | |
96 | return 0; | |
97 | ||
98 | /* Timeout of a tree mount is determined by its top dentry */ | |
99 | if (!autofs4_can_expire(top, timeout, do_now)) | |
100 | return 0; | |
101 | ||
102 | spin_lock(&dcache_lock); | |
103 | repeat: | |
104 | next = this_parent->d_subdirs.next; | |
105 | resume: | |
106 | while (next != &this_parent->d_subdirs) { | |
107 | struct dentry *dentry = list_entry(next, struct dentry, d_child); | |
108 | ||
109 | /* Negative dentry - give up */ | |
110 | if (!simple_positive(dentry)) { | |
111 | next = next->next; | |
112 | continue; | |
113 | } | |
114 | ||
115 | DPRINTK("dentry %p %.*s", | |
116 | dentry, (int)dentry->d_name.len, dentry->d_name.name); | |
117 | ||
118 | if (!simple_empty_nolock(dentry)) { | |
119 | this_parent = dentry; | |
120 | goto repeat; | |
121 | } | |
122 | ||
123 | dentry = dget(dentry); | |
124 | spin_unlock(&dcache_lock); | |
125 | ||
126 | if (d_mountpoint(dentry)) { | |
127 | /* First busy => tree busy */ | |
128 | if (!autofs4_check_mount(mnt, dentry)) { | |
129 | dput(dentry); | |
130 | return 0; | |
131 | } | |
132 | } | |
133 | ||
134 | dput(dentry); | |
135 | spin_lock(&dcache_lock); | |
136 | next = next->next; | |
137 | } | |
138 | ||
139 | if (this_parent != top) { | |
140 | next = this_parent->d_child.next; | |
141 | this_parent = this_parent->d_parent; | |
142 | goto resume; | |
143 | } | |
144 | spin_unlock(&dcache_lock); | |
145 | ||
146 | return 1; | |
147 | } | |
148 | ||
149 | static struct dentry *autofs4_check_leaves(struct vfsmount *mnt, | |
150 | struct dentry *parent, | |
151 | unsigned long timeout, | |
152 | int do_now) | |
153 | { | |
154 | struct dentry *this_parent = parent; | |
155 | struct list_head *next; | |
156 | ||
157 | DPRINTK("parent %p %.*s", | |
158 | parent, (int)parent->d_name.len, parent->d_name.name); | |
159 | ||
160 | spin_lock(&dcache_lock); | |
161 | repeat: | |
162 | next = this_parent->d_subdirs.next; | |
163 | resume: | |
164 | while (next != &this_parent->d_subdirs) { | |
165 | struct dentry *dentry = list_entry(next, struct dentry, d_child); | |
166 | ||
167 | /* Negative dentry - give up */ | |
168 | if (!simple_positive(dentry)) { | |
169 | next = next->next; | |
170 | continue; | |
171 | } | |
172 | ||
173 | DPRINTK("dentry %p %.*s", | |
174 | dentry, (int)dentry->d_name.len, dentry->d_name.name); | |
175 | ||
176 | if (!list_empty(&dentry->d_subdirs)) { | |
177 | this_parent = dentry; | |
178 | goto repeat; | |
179 | } | |
180 | ||
181 | dentry = dget(dentry); | |
182 | spin_unlock(&dcache_lock); | |
183 | ||
184 | if (d_mountpoint(dentry)) { | |
185 | /* Can we expire this guy */ | |
186 | if (!autofs4_can_expire(dentry, timeout, do_now)) | |
187 | goto cont; | |
188 | ||
189 | /* Can we umount this guy */ | |
190 | if (autofs4_check_mount(mnt, dentry)) | |
191 | return dentry; | |
192 | ||
193 | } | |
194 | cont: | |
195 | dput(dentry); | |
196 | spin_lock(&dcache_lock); | |
197 | next = next->next; | |
198 | } | |
199 | ||
200 | if (this_parent != parent) { | |
201 | next = this_parent->d_child.next; | |
202 | this_parent = this_parent->d_parent; | |
203 | goto resume; | |
204 | } | |
205 | spin_unlock(&dcache_lock); | |
206 | ||
207 | return NULL; | |
208 | } | |
209 | ||
210 | /* | |
211 | * Find an eligible tree to time-out | |
212 | * A tree is eligible if :- | |
213 | * - it is unused by any user process | |
214 | * - it has been unused for exp_timeout time | |
215 | */ | |
216 | static struct dentry *autofs4_expire(struct super_block *sb, | |
217 | struct vfsmount *mnt, | |
218 | struct autofs_sb_info *sbi, | |
219 | int how) | |
220 | { | |
221 | unsigned long timeout; | |
222 | struct dentry *root = sb->s_root; | |
223 | struct dentry *expired = NULL; | |
224 | struct list_head *next; | |
225 | int do_now = how & AUTOFS_EXP_IMMEDIATE; | |
226 | int exp_leaves = how & AUTOFS_EXP_LEAVES; | |
227 | ||
228 | if ( !sbi->exp_timeout || !root ) | |
229 | return NULL; | |
230 | ||
231 | now = jiffies; | |
232 | timeout = sbi->exp_timeout; | |
233 | ||
234 | spin_lock(&dcache_lock); | |
235 | next = root->d_subdirs.next; | |
236 | ||
237 | /* On exit from the loop expire is set to a dgot dentry | |
238 | * to expire or it's NULL */ | |
239 | while ( next != &root->d_subdirs ) { | |
240 | struct dentry *dentry = list_entry(next, struct dentry, d_child); | |
241 | ||
242 | /* Negative dentry - give up */ | |
243 | if ( !simple_positive(dentry) ) { | |
244 | next = next->next; | |
245 | continue; | |
246 | } | |
247 | ||
248 | dentry = dget(dentry); | |
249 | spin_unlock(&dcache_lock); | |
250 | ||
251 | /* Case 1: indirect mount or top level direct mount */ | |
252 | if (d_mountpoint(dentry)) { | |
253 | DPRINTK("checking mountpoint %p %.*s", | |
254 | dentry, (int)dentry->d_name.len, dentry->d_name.name); | |
255 | ||
256 | /* Can we expire this guy */ | |
257 | if (!autofs4_can_expire(dentry, timeout, do_now)) | |
258 | goto next; | |
259 | ||
260 | /* Can we umount this guy */ | |
261 | if (autofs4_check_mount(mnt, dentry)) { | |
262 | expired = dentry; | |
263 | break; | |
264 | } | |
265 | goto next; | |
266 | } | |
267 | ||
268 | if ( simple_empty(dentry) ) | |
269 | goto next; | |
270 | ||
271 | /* Case 2: tree mount, expire iff entire tree is not busy */ | |
272 | if (!exp_leaves) { | |
273 | if (autofs4_check_tree(mnt, dentry, timeout, do_now)) { | |
274 | expired = dentry; | |
275 | break; | |
276 | } | |
277 | /* Case 3: direct mount, expire individual leaves */ | |
278 | } else { | |
279 | expired = autofs4_check_leaves(mnt, dentry, timeout, do_now); | |
280 | if (expired) { | |
281 | dput(dentry); | |
282 | break; | |
283 | } | |
284 | } | |
285 | next: | |
286 | dput(dentry); | |
287 | spin_lock(&dcache_lock); | |
288 | next = next->next; | |
289 | } | |
290 | ||
291 | if ( expired ) { | |
292 | DPRINTK("returning %p %.*s", | |
293 | expired, (int)expired->d_name.len, expired->d_name.name); | |
294 | spin_lock(&dcache_lock); | |
295 | list_del(&expired->d_parent->d_subdirs); | |
296 | list_add(&expired->d_parent->d_subdirs, &expired->d_child); | |
297 | spin_unlock(&dcache_lock); | |
298 | return expired; | |
299 | } | |
300 | spin_unlock(&dcache_lock); | |
301 | ||
302 | return NULL; | |
303 | } | |
304 | ||
305 | /* Perform an expiry operation */ | |
306 | int autofs4_expire_run(struct super_block *sb, | |
307 | struct vfsmount *mnt, | |
308 | struct autofs_sb_info *sbi, | |
309 | struct autofs_packet_expire __user *pkt_p) | |
310 | { | |
311 | struct autofs_packet_expire pkt; | |
312 | struct dentry *dentry; | |
313 | ||
314 | memset(&pkt,0,sizeof pkt); | |
315 | ||
316 | pkt.hdr.proto_version = sbi->version; | |
317 | pkt.hdr.type = autofs_ptype_expire; | |
318 | ||
319 | if ((dentry = autofs4_expire(sb, mnt, sbi, 0)) == NULL) | |
320 | return -EAGAIN; | |
321 | ||
322 | pkt.len = dentry->d_name.len; | |
323 | memcpy(pkt.name, dentry->d_name.name, pkt.len); | |
324 | pkt.name[pkt.len] = '\0'; | |
325 | dput(dentry); | |
326 | ||
327 | if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) ) | |
328 | return -EFAULT; | |
329 | ||
330 | return 0; | |
331 | } | |
332 | ||
333 | /* Call repeatedly until it returns -EAGAIN, meaning there's nothing | |
334 | more to be done */ | |
335 | int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt, | |
336 | struct autofs_sb_info *sbi, int __user *arg) | |
337 | { | |
338 | struct dentry *dentry; | |
339 | int ret = -EAGAIN; | |
340 | int do_now = 0; | |
341 | ||
342 | if (arg && get_user(do_now, arg)) | |
343 | return -EFAULT; | |
344 | ||
345 | if ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) { | |
346 | struct autofs_info *de_info = autofs4_dentry_ino(dentry); | |
347 | ||
348 | /* This is synchronous because it makes the daemon a | |
349 | little easier */ | |
350 | de_info->flags |= AUTOFS_INF_EXPIRING; | |
351 | ret = autofs4_wait(sbi, dentry, NFY_EXPIRE); | |
352 | de_info->flags &= ~AUTOFS_INF_EXPIRING; | |
353 | dput(dentry); | |
354 | } | |
355 | ||
356 | return ret; | |
357 | } | |
358 |