1 /* -*- c -*- --------------------------------------------------------------- *
3 * linux/fs/autofs/expire.c
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>
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.
13 * ------------------------------------------------------------------------- */
17 static unsigned long now;
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)
23 struct autofs_info *ino = autofs4_dentry_ino(dentry);
25 /* dentry in the process of being deleted */
30 /* Too young to die */
31 if (!timeout || time_after(ino->last_used + timeout, now))
34 /* update last_used here :-
35 - obviously makes sense if it is in use now
36 - less obviously, prevents rapid-fire expire
37 attempts if expire fails the first time */
43 /* Check a mount point for busyness */
44 static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
46 struct dentry *top = dentry;
47 struct path path = {.mnt = mnt, .dentry = dentry};
50 DPRINTK("dentry %p %.*s",
51 dentry, (int)dentry->d_name.len, dentry->d_name.name);
55 if (!follow_down_one(&path))
58 if (is_autofs4_dentry(path.dentry)) {
59 struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb);
61 /* This is an autofs submount, we can't expire it */
62 if (autofs_type_indirect(sbi->type))
66 /* Update the expiry counter if fs is busy */
67 if (!may_umount_tree(path.mnt)) {
68 struct autofs_info *ino = autofs4_dentry_ino(top);
69 ino->last_used = jiffies;
75 DPRINTK("returning = %d", status);
81 * Calculate and dget next entry in the subdirs list under root.
83 static struct dentry *get_next_positive_subdir(struct dentry *prev,
86 struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
87 struct list_head *next;
90 spin_lock(&sbi->lookup_lock);
91 spin_lock(&root->d_lock);
94 next = prev->d_u.d_child.next;
96 prev = dget_dlock(root);
97 next = prev->d_subdirs.next;
101 if (next == &root->d_subdirs) {
102 spin_unlock(&root->d_lock);
103 spin_unlock(&sbi->lookup_lock);
108 q = list_entry(next, struct dentry, d_u.d_child);
110 spin_lock_nested(&q->d_lock, DENTRY_D_LOCK_NESTED);
111 /* Already gone or negative dentry (under construction) - try next */
112 if (!d_count(q) || !simple_positive(q)) {
113 spin_unlock(&q->d_lock);
114 next = q->d_u.d_child.next;
118 spin_unlock(&q->d_lock);
119 spin_unlock(&root->d_lock);
120 spin_unlock(&sbi->lookup_lock);
128 * Calculate and dget next entry in top down tree traversal.
130 static struct dentry *get_next_positive_dentry(struct dentry *prev,
133 struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
134 struct list_head *next;
135 struct dentry *p, *ret;
140 spin_lock(&sbi->lookup_lock);
143 spin_lock(&p->d_lock);
145 next = p->d_subdirs.next;
146 if (next == &p->d_subdirs) {
148 struct dentry *parent;
151 spin_unlock(&p->d_lock);
152 spin_unlock(&sbi->lookup_lock);
157 parent = p->d_parent;
158 if (!spin_trylock(&parent->d_lock)) {
159 spin_unlock(&p->d_lock);
163 spin_unlock(&p->d_lock);
164 next = p->d_u.d_child.next;
166 if (next != &parent->d_subdirs)
170 ret = list_entry(next, struct dentry, d_u.d_child);
172 spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
173 /* Negative dentry - try next */
174 if (!simple_positive(ret)) {
175 spin_unlock(&p->d_lock);
176 lock_set_subclass(&ret->d_lock.dep_map, 0, _RET_IP_);
181 spin_unlock(&ret->d_lock);
182 spin_unlock(&p->d_lock);
183 spin_unlock(&sbi->lookup_lock);
191 * Check a direct mount point for busyness.
192 * Direct mounts have similar expiry semantics to tree mounts.
193 * The tree is not busy iff no mountpoints are busy and there are no
196 static int autofs4_direct_busy(struct vfsmount *mnt,
198 unsigned long timeout,
201 DPRINTK("top %p %.*s",
202 top, (int) top->d_name.len, top->d_name.name);
204 /* If it's busy update the expiry counters */
205 if (!may_umount_tree(mnt)) {
206 struct autofs_info *ino = autofs4_dentry_ino(top);
208 ino->last_used = jiffies;
212 /* Timeout of a direct mount is determined by its top dentry */
213 if (!autofs4_can_expire(top, timeout, do_now))
219 /* Check a directory tree of mount points for busyness
220 * The tree is not busy iff no mountpoints are busy
222 static int autofs4_tree_busy(struct vfsmount *mnt,
224 unsigned long timeout,
227 struct autofs_info *top_ino = autofs4_dentry_ino(top);
230 DPRINTK("top %p %.*s",
231 top, (int)top->d_name.len, top->d_name.name);
233 /* Negative dentry - give up */
234 if (!simple_positive(top))
238 while ((p = get_next_positive_dentry(p, top))) {
239 DPRINTK("dentry %p %.*s",
240 p, (int) p->d_name.len, p->d_name.name);
243 * Is someone visiting anywhere in the subtree ?
244 * If there's no mount we need to check the usage
245 * count for the autofs dentry.
246 * If the fs is busy update the expiry counter.
248 if (d_mountpoint(p)) {
249 if (autofs4_mount_busy(mnt, p)) {
250 top_ino->last_used = jiffies;
255 struct autofs_info *ino = autofs4_dentry_ino(p);
256 unsigned int ino_count = atomic_read(&ino->count);
259 * Clean stale dentries below that have not been
260 * invalidated after a mount fail during lookup
264 /* allow for dget above and top is already dgot */
270 if (d_count(p) > ino_count) {
271 top_ino->last_used = jiffies;
278 /* Timeout of a tree mount is ultimately determined by its top dentry */
279 if (!autofs4_can_expire(top, timeout, do_now))
285 static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
286 struct dentry *parent,
287 unsigned long timeout,
292 DPRINTK("parent %p %.*s",
293 parent, (int)parent->d_name.len, parent->d_name.name);
296 while ((p = get_next_positive_dentry(p, parent))) {
297 DPRINTK("dentry %p %.*s",
298 p, (int) p->d_name.len, p->d_name.name);
300 if (d_mountpoint(p)) {
301 /* Can we umount this guy */
302 if (autofs4_mount_busy(mnt, p))
305 /* Can we expire this guy */
306 if (autofs4_can_expire(p, timeout, do_now))
313 /* Check if we can expire a direct mount (possibly a tree) */
314 struct dentry *autofs4_expire_direct(struct super_block *sb,
315 struct vfsmount *mnt,
316 struct autofs_sb_info *sbi,
319 unsigned long timeout;
320 struct dentry *root = dget(sb->s_root);
321 int do_now = how & AUTOFS_EXP_IMMEDIATE;
322 struct autofs_info *ino;
328 timeout = sbi->exp_timeout;
330 spin_lock(&sbi->fs_lock);
331 ino = autofs4_dentry_ino(root);
332 /* No point expiring a pending mount */
333 if (ino->flags & AUTOFS_INF_PENDING)
335 if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
336 ino->flags |= AUTOFS_INF_EXPIRING;
337 init_completion(&ino->expire_complete);
338 spin_unlock(&sbi->fs_lock);
342 spin_unlock(&sbi->fs_lock);
349 * Find an eligible tree to time-out
350 * A tree is eligible if :-
351 * - it is unused by any user process
352 * - it has been unused for exp_timeout time
354 struct dentry *autofs4_expire_indirect(struct super_block *sb,
355 struct vfsmount *mnt,
356 struct autofs_sb_info *sbi,
359 unsigned long timeout;
360 struct dentry *root = sb->s_root;
361 struct dentry *dentry;
362 struct dentry *expired = NULL;
363 int do_now = how & AUTOFS_EXP_IMMEDIATE;
364 int exp_leaves = how & AUTOFS_EXP_LEAVES;
365 struct autofs_info *ino;
366 unsigned int ino_count;
372 timeout = sbi->exp_timeout;
375 while ((dentry = get_next_positive_subdir(dentry, root))) {
376 spin_lock(&sbi->fs_lock);
377 ino = autofs4_dentry_ino(dentry);
378 /* No point expiring a pending mount */
379 if (ino->flags & AUTOFS_INF_PENDING)
383 * Case 1: (i) indirect mount or top level pseudo direct mount
385 * (ii) indirect mount with offset mount, check the "/"
386 * offset (autofs-5.0+).
388 if (d_mountpoint(dentry)) {
389 DPRINTK("checking mountpoint %p %.*s",
390 dentry, (int)dentry->d_name.len, dentry->d_name.name);
392 /* Can we umount this guy */
393 if (autofs4_mount_busy(mnt, dentry))
396 /* Can we expire this guy */
397 if (autofs4_can_expire(dentry, timeout, do_now)) {
404 if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
405 DPRINTK("checking symlink %p %.*s",
406 dentry, (int)dentry->d_name.len, dentry->d_name.name);
408 * A symlink can't be "busy" in the usual sense so
409 * just check last used for expire timeout.
411 if (autofs4_can_expire(dentry, timeout, do_now)) {
418 if (simple_empty(dentry))
421 /* Case 2: tree mount, expire iff entire tree is not busy */
423 /* Path walk currently on this dentry? */
424 ino_count = atomic_read(&ino->count) + 1;
425 if (d_count(dentry) > ino_count)
428 if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
433 * Case 3: pseudo direct mount, expire individual leaves
437 /* Path walk currently on this dentry? */
438 ino_count = atomic_read(&ino->count) + 1;
439 if (d_count(dentry) > ino_count)
442 expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
449 spin_unlock(&sbi->fs_lock);
454 DPRINTK("returning %p %.*s",
455 expired, (int)expired->d_name.len, expired->d_name.name);
456 ino = autofs4_dentry_ino(expired);
457 ino->flags |= AUTOFS_INF_EXPIRING;
458 init_completion(&ino->expire_complete);
459 spin_unlock(&sbi->fs_lock);
460 spin_lock(&sbi->lookup_lock);
461 spin_lock(&expired->d_parent->d_lock);
462 spin_lock_nested(&expired->d_lock, DENTRY_D_LOCK_NESTED);
463 list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
464 spin_unlock(&expired->d_lock);
465 spin_unlock(&expired->d_parent->d_lock);
466 spin_unlock(&sbi->lookup_lock);
470 int autofs4_expire_wait(struct dentry *dentry)
472 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
473 struct autofs_info *ino = autofs4_dentry_ino(dentry);
476 /* Block on any pending expire */
477 spin_lock(&sbi->fs_lock);
478 if (ino->flags & AUTOFS_INF_EXPIRING) {
479 spin_unlock(&sbi->fs_lock);
481 DPRINTK("waiting for expire %p name=%.*s",
482 dentry, dentry->d_name.len, dentry->d_name.name);
484 status = autofs4_wait(sbi, dentry, NFY_NONE);
485 wait_for_completion(&ino->expire_complete);
487 DPRINTK("expire done status=%d", status);
489 if (d_unhashed(dentry))
494 spin_unlock(&sbi->fs_lock);
499 /* Perform an expiry operation */
500 int autofs4_expire_run(struct super_block *sb,
501 struct vfsmount *mnt,
502 struct autofs_sb_info *sbi,
503 struct autofs_packet_expire __user *pkt_p)
505 struct autofs_packet_expire pkt;
506 struct autofs_info *ino;
507 struct dentry *dentry;
510 memset(&pkt,0,sizeof pkt);
512 pkt.hdr.proto_version = sbi->version;
513 pkt.hdr.type = autofs_ptype_expire;
515 if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
518 pkt.len = dentry->d_name.len;
519 memcpy(pkt.name, dentry->d_name.name, pkt.len);
520 pkt.name[pkt.len] = '\0';
523 if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
526 spin_lock(&sbi->fs_lock);
527 ino = autofs4_dentry_ino(dentry);
528 ino->flags &= ~AUTOFS_INF_EXPIRING;
529 complete_all(&ino->expire_complete);
530 spin_unlock(&sbi->fs_lock);
535 int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
536 struct autofs_sb_info *sbi, int when)
538 struct dentry *dentry;
541 if (autofs_type_trigger(sbi->type))
542 dentry = autofs4_expire_direct(sb, mnt, sbi, when);
544 dentry = autofs4_expire_indirect(sb, mnt, sbi, when);
547 struct autofs_info *ino = autofs4_dentry_ino(dentry);
549 /* This is synchronous because it makes the daemon a
551 ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
553 spin_lock(&sbi->fs_lock);
554 ino->flags &= ~AUTOFS_INF_EXPIRING;
555 complete_all(&ino->expire_complete);
556 spin_unlock(&sbi->fs_lock);
563 /* Call repeatedly until it returns -EAGAIN, meaning there's nothing
565 int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
566 struct autofs_sb_info *sbi, int __user *arg)
570 if (arg && get_user(do_now, arg))
573 return autofs4_do_expire_multi(sb, mnt, sbi, do_now);