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 */
29 /* No point expiring a pending mount */
30 if (ino
->flags
& AUTOFS_INF_PENDING
)
34 /* Too young to die */
35 if (!timeout
|| time_after(ino
->last_used
+ timeout
, now
))
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 */
47 /* Check a mount point for busyness */
48 static int autofs4_mount_busy(struct vfsmount
*mnt
, struct dentry
*dentry
)
50 struct dentry
*top
= dentry
;
51 struct path path
= {.mnt
= mnt
, .dentry
= dentry
};
54 DPRINTK("dentry %p %.*s",
55 dentry
, (int)dentry
->d_name
.len
, dentry
->d_name
.name
);
59 if (!follow_down(&path
))
62 if (is_autofs4_dentry(path
.dentry
)) {
63 struct autofs_sb_info
*sbi
= autofs4_sbi(path
.dentry
->d_sb
);
65 /* This is an autofs submount, we can't expire it */
66 if (autofs_type_indirect(sbi
->type
))
70 * Otherwise it's an offset mount and we need to check
71 * if we can umount its mount, if there is one.
73 if (!d_mountpoint(path
.dentry
)) {
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
;
88 DPRINTK("returning = %d", status
);
94 * Calculate and dget next entry in top down tree traversal.
96 static struct dentry
*get_next_positive_dentry(struct dentry
*prev
,
99 struct list_head
*next
;
100 struct dentry
*p
, *ret
;
105 spin_lock(&autofs4_lock
);
108 spin_lock(&p
->d_lock
);
110 next
= p
->d_subdirs
.next
;
111 if (next
== &p
->d_subdirs
) {
113 struct dentry
*parent
;
116 spin_unlock(&p
->d_lock
);
117 spin_unlock(&autofs4_lock
);
122 parent
= p
->d_parent
;
123 if (!spin_trylock(&parent
->d_lock
)) {
124 spin_unlock(&p
->d_lock
);
128 spin_unlock(&p
->d_lock
);
129 next
= p
->d_u
.d_child
.next
;
131 if (next
!= &parent
->d_subdirs
)
135 ret
= list_entry(next
, struct dentry
, d_u
.d_child
);
137 spin_lock_nested(&ret
->d_lock
, DENTRY_D_LOCK_NESTED
);
138 /* Negative dentry - try next */
139 if (!simple_positive(ret
)) {
140 spin_unlock(&ret
->d_lock
);
145 spin_unlock(&ret
->d_lock
);
146 spin_unlock(&p
->d_lock
);
147 spin_unlock(&autofs4_lock
);
155 * Check a direct mount point for busyness.
156 * Direct mounts have similar expiry semantics to tree mounts.
157 * The tree is not busy iff no mountpoints are busy and there are no
160 static int autofs4_direct_busy(struct vfsmount
*mnt
,
162 unsigned long timeout
,
165 DPRINTK("top %p %.*s",
166 top
, (int) top
->d_name
.len
, top
->d_name
.name
);
168 /* If it's busy update the expiry counters */
169 if (!may_umount_tree(mnt
)) {
170 struct autofs_info
*ino
= autofs4_dentry_ino(top
);
172 ino
->last_used
= jiffies
;
176 /* Timeout of a direct mount is determined by its top dentry */
177 if (!autofs4_can_expire(top
, timeout
, do_now
))
183 /* Check a directory tree of mount points for busyness
184 * The tree is not busy iff no mountpoints are busy
186 static int autofs4_tree_busy(struct vfsmount
*mnt
,
188 unsigned long timeout
,
191 struct autofs_info
*top_ino
= autofs4_dentry_ino(top
);
194 DPRINTK("top %p %.*s",
195 top
, (int)top
->d_name
.len
, top
->d_name
.name
);
197 /* Negative dentry - give up */
198 if (!simple_positive(top
))
202 while ((p
= get_next_positive_dentry(p
, top
))) {
203 DPRINTK("dentry %p %.*s",
204 p
, (int) p
->d_name
.len
, p
->d_name
.name
);
207 * Is someone visiting anywhere in the subtree ?
208 * If there's no mount we need to check the usage
209 * count for the autofs dentry.
210 * If the fs is busy update the expiry counter.
212 if (d_mountpoint(p
)) {
213 if (autofs4_mount_busy(mnt
, p
)) {
214 top_ino
->last_used
= jiffies
;
219 struct autofs_info
*ino
= autofs4_dentry_ino(p
);
220 unsigned int ino_count
= atomic_read(&ino
->count
);
223 * Clean stale dentries below that have not been
224 * invalidated after a mount fail during lookup
228 /* allow for dget above and top is already dgot */
234 if (p
->d_count
> ino_count
) {
235 top_ino
->last_used
= jiffies
;
242 /* Timeout of a tree mount is ultimately determined by its top dentry */
243 if (!autofs4_can_expire(top
, timeout
, do_now
))
249 static struct dentry
*autofs4_check_leaves(struct vfsmount
*mnt
,
250 struct dentry
*parent
,
251 unsigned long timeout
,
256 DPRINTK("parent %p %.*s",
257 parent
, (int)parent
->d_name
.len
, parent
->d_name
.name
);
260 while ((p
= get_next_positive_dentry(p
, parent
))) {
261 DPRINTK("dentry %p %.*s",
262 p
, (int) p
->d_name
.len
, p
->d_name
.name
);
264 if (d_mountpoint(p
)) {
265 /* Can we umount this guy */
266 if (autofs4_mount_busy(mnt
, p
))
269 /* Can we expire this guy */
270 if (autofs4_can_expire(p
, timeout
, do_now
))
277 /* Check if we can expire a direct mount (possibly a tree) */
278 struct dentry
*autofs4_expire_direct(struct super_block
*sb
,
279 struct vfsmount
*mnt
,
280 struct autofs_sb_info
*sbi
,
283 unsigned long timeout
;
284 struct dentry
*root
= dget(sb
->s_root
);
285 int do_now
= how
& AUTOFS_EXP_IMMEDIATE
;
291 timeout
= sbi
->exp_timeout
;
293 spin_lock(&sbi
->fs_lock
);
294 if (!autofs4_direct_busy(mnt
, root
, timeout
, do_now
)) {
295 struct autofs_info
*ino
= autofs4_dentry_ino(root
);
296 if (d_mountpoint(root
)) {
297 ino
->flags
|= AUTOFS_INF_MOUNTPOINT
;
298 spin_lock(&root
->d_lock
);
299 root
->d_flags
&= ~DCACHE_MOUNTED
;
300 spin_unlock(&root
->d_lock
);
302 ino
->flags
|= AUTOFS_INF_EXPIRING
;
303 init_completion(&ino
->expire_complete
);
304 spin_unlock(&sbi
->fs_lock
);
307 spin_unlock(&sbi
->fs_lock
);
314 * Find an eligible tree to time-out
315 * A tree is eligible if :-
316 * - it is unused by any user process
317 * - it has been unused for exp_timeout time
319 struct dentry
*autofs4_expire_indirect(struct super_block
*sb
,
320 struct vfsmount
*mnt
,
321 struct autofs_sb_info
*sbi
,
324 unsigned long timeout
;
325 struct dentry
*root
= sb
->s_root
;
326 struct dentry
*dentry
;
327 struct dentry
*expired
= NULL
;
328 int do_now
= how
& AUTOFS_EXP_IMMEDIATE
;
329 int exp_leaves
= how
& AUTOFS_EXP_LEAVES
;
330 struct autofs_info
*ino
;
331 unsigned int ino_count
;
337 timeout
= sbi
->exp_timeout
;
340 while ((dentry
= get_next_positive_dentry(dentry
, root
))) {
341 spin_lock(&sbi
->fs_lock
);
342 ino
= autofs4_dentry_ino(dentry
);
345 * Case 1: (i) indirect mount or top level pseudo direct mount
347 * (ii) indirect mount with offset mount, check the "/"
348 * offset (autofs-5.0+).
350 if (d_mountpoint(dentry
)) {
351 DPRINTK("checking mountpoint %p %.*s",
352 dentry
, (int)dentry
->d_name
.len
, dentry
->d_name
.name
);
354 /* Path walk currently on this dentry? */
355 ino_count
= atomic_read(&ino
->count
) + 2;
356 if (dentry
->d_count
> ino_count
)
359 /* Can we umount this guy */
360 if (autofs4_mount_busy(mnt
, dentry
))
363 /* Can we expire this guy */
364 if (autofs4_can_expire(dentry
, timeout
, do_now
)) {
371 if (simple_empty(dentry
))
374 /* Case 2: tree mount, expire iff entire tree is not busy */
376 /* Path walk currently on this dentry? */
377 ino_count
= atomic_read(&ino
->count
) + 1;
378 if (dentry
->d_count
> ino_count
)
381 if (!autofs4_tree_busy(mnt
, dentry
, timeout
, do_now
)) {
386 * Case 3: pseudo direct mount, expire individual leaves
390 /* Path walk currently on this dentry? */
391 ino_count
= atomic_read(&ino
->count
) + 1;
392 if (dentry
->d_count
> ino_count
)
395 expired
= autofs4_check_leaves(mnt
, dentry
, timeout
, do_now
);
402 spin_unlock(&sbi
->fs_lock
);
407 DPRINTK("returning %p %.*s",
408 expired
, (int)expired
->d_name
.len
, expired
->d_name
.name
);
409 ino
= autofs4_dentry_ino(expired
);
410 ino
->flags
|= AUTOFS_INF_EXPIRING
;
411 init_completion(&ino
->expire_complete
);
412 spin_unlock(&sbi
->fs_lock
);
413 spin_lock(&autofs4_lock
);
414 spin_lock(&expired
->d_parent
->d_lock
);
415 spin_lock_nested(&expired
->d_lock
, DENTRY_D_LOCK_NESTED
);
416 list_move(&expired
->d_parent
->d_subdirs
, &expired
->d_u
.d_child
);
417 spin_unlock(&expired
->d_lock
);
418 spin_unlock(&expired
->d_parent
->d_lock
);
419 spin_unlock(&autofs4_lock
);
423 int autofs4_expire_wait(struct dentry
*dentry
)
425 struct autofs_sb_info
*sbi
= autofs4_sbi(dentry
->d_sb
);
426 struct autofs_info
*ino
= autofs4_dentry_ino(dentry
);
429 /* Block on any pending expire */
430 spin_lock(&sbi
->fs_lock
);
431 if (ino
->flags
& AUTOFS_INF_EXPIRING
) {
432 spin_unlock(&sbi
->fs_lock
);
434 DPRINTK("waiting for expire %p name=%.*s",
435 dentry
, dentry
->d_name
.len
, dentry
->d_name
.name
);
437 status
= autofs4_wait(sbi
, dentry
, NFY_NONE
);
438 wait_for_completion(&ino
->expire_complete
);
440 DPRINTK("expire done status=%d", status
);
442 if (d_unhashed(dentry
))
447 spin_unlock(&sbi
->fs_lock
);
452 /* Perform an expiry operation */
453 int autofs4_expire_run(struct super_block
*sb
,
454 struct vfsmount
*mnt
,
455 struct autofs_sb_info
*sbi
,
456 struct autofs_packet_expire __user
*pkt_p
)
458 struct autofs_packet_expire pkt
;
459 struct autofs_info
*ino
;
460 struct dentry
*dentry
;
463 memset(&pkt
,0,sizeof pkt
);
465 pkt
.hdr
.proto_version
= sbi
->version
;
466 pkt
.hdr
.type
= autofs_ptype_expire
;
468 if ((dentry
= autofs4_expire_indirect(sb
, mnt
, sbi
, 0)) == NULL
)
471 pkt
.len
= dentry
->d_name
.len
;
472 memcpy(pkt
.name
, dentry
->d_name
.name
, pkt
.len
);
473 pkt
.name
[pkt
.len
] = '\0';
476 if ( copy_to_user(pkt_p
, &pkt
, sizeof(struct autofs_packet_expire
)) )
479 spin_lock(&sbi
->fs_lock
);
480 ino
= autofs4_dentry_ino(dentry
);
481 ino
->flags
&= ~AUTOFS_INF_EXPIRING
;
482 complete_all(&ino
->expire_complete
);
483 spin_unlock(&sbi
->fs_lock
);
488 int autofs4_do_expire_multi(struct super_block
*sb
, struct vfsmount
*mnt
,
489 struct autofs_sb_info
*sbi
, int when
)
491 struct dentry
*dentry
;
494 if (autofs_type_trigger(sbi
->type
))
495 dentry
= autofs4_expire_direct(sb
, mnt
, sbi
, when
);
497 dentry
= autofs4_expire_indirect(sb
, mnt
, sbi
, when
);
500 struct autofs_info
*ino
= autofs4_dentry_ino(dentry
);
502 /* This is synchronous because it makes the daemon a
504 ret
= autofs4_wait(sbi
, dentry
, NFY_EXPIRE
);
506 spin_lock(&sbi
->fs_lock
);
507 if (ino
->flags
& AUTOFS_INF_MOUNTPOINT
) {
508 spin_lock(&sb
->s_root
->d_lock
);
510 * If we haven't been expired away, then reset
513 if (mnt
->mnt_parent
!= mnt
)
514 sb
->s_root
->d_flags
|= DCACHE_MOUNTED
;
515 spin_unlock(&sb
->s_root
->d_lock
);
516 ino
->flags
&= ~AUTOFS_INF_MOUNTPOINT
;
518 ino
->flags
&= ~AUTOFS_INF_EXPIRING
;
519 complete_all(&ino
->expire_complete
);
520 spin_unlock(&sbi
->fs_lock
);
527 /* Call repeatedly until it returns -EAGAIN, meaning there's nothing
529 int autofs4_expire_multi(struct super_block
*sb
, struct vfsmount
*mnt
,
530 struct autofs_sb_info
*sbi
, int __user
*arg
)
534 if (arg
&& get_user(do_now
, arg
))
537 return autofs4_do_expire_multi(sb
, mnt
, sbi
, do_now
);