[deliverable/linux.git] / fs / autofs4 / expire.c

/* -*- c -*- --------------------------------------------------------------- *
 *
 * linux/fs/autofs/expire.c
 *
 *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
 *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
 *  Copyright 2001-2006 Ian Kent <raven@themaw.net>
 *
 * This file is part of the Linux kernel and is made available under
 * the terms of the GNU General Public License, version 2, or at your
 * option, any later version, incorporated herein by reference.
 *
 * ------------------------------------------------------------------------- */

#include "autofs_i.h"

static unsigned long now;

/* Check if a dentry can be expired */
static inline int autofs4_can_expire(struct dentry *dentry,
					unsigned long timeout, int do_now)
{
	struct autofs_info *ino = autofs4_dentry_ino(dentry);

	/* dentry in the process of being deleted */
	if (ino == NULL)
		return 0;

	if (!do_now) {
		/* Too young to die */
		if (!timeout || time_after(ino->last_used + timeout, now))
			return 0;

		/* update last_used here :-
		   - obviously makes sense if it is in use now
		   - less obviously, prevents rapid-fire expire
		     attempts if expire fails the first time */
		ino->last_used = now;
	}
	return 1;
}

/* Check a mount point for busyness */
static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
{
	struct dentry *top = dentry;
	struct path path = {.mnt = mnt, .dentry = dentry};
	int status = 1;

	DPRINTK("dentry %p %.*s",
		dentry, (int)dentry->d_name.len, dentry->d_name.name);

	path_get(&path);

	if (!follow_down_one(&path))
		goto done;

	if (is_autofs4_dentry(path.dentry)) {
		struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb);

		/* This is an autofs submount, we can't expire it */
		if (autofs_type_indirect(sbi->type))
			goto done;

		/*
		 * Otherwise it's an offset mount and we need to check
		 * if we can umount its mount, if there is one.
		 */
		if (!d_mountpoint(path.dentry)) {
			status = 0;
			goto done;
		}
	}

	/* Update the expiry counter if fs is busy */
	if (!may_umount_tree(path.mnt)) {
		struct autofs_info *ino = autofs4_dentry_ino(top);
		ino->last_used = jiffies;
		goto done;
	}

	status = 0;
done:
	DPRINTK("returning = %d", status);
	path_put(&path);
	return status;
}

/*
 * Calculate and dget next entry in top down tree traversal.
 */
static struct dentry *get_next_positive_dentry(struct dentry *prev,
						struct dentry *root)
{
	struct list_head *next;
	struct dentry *p, *ret;

	if (prev == NULL)
		return dget(prev);

	spin_lock(&autofs4_lock);
relock:
	p = prev;
	spin_lock(&p->d_lock);
again:
	next = p->d_subdirs.next;
	if (next == &p->d_subdirs) {
		while (1) {
			struct dentry *parent;

			if (p == root) {
				spin_unlock(&p->d_lock);
				spin_unlock(&autofs4_lock);
				dput(prev);
				return NULL;
			}

			parent = p->d_parent;
			if (!spin_trylock(&parent->d_lock)) {
				spin_unlock(&p->d_lock);
				cpu_relax();
				goto relock;
			}
			spin_unlock(&p->d_lock);
			next = p->d_u.d_child.next;
			p = parent;
			if (next != &parent->d_subdirs)
				break;
		}
	}
	ret = list_entry(next, struct dentry, d_u.d_child);

	spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
	/* Negative dentry - try next */
	if (!simple_positive(ret)) {
		spin_unlock(&ret->d_lock);
		p = ret;
		goto again;
	}
	dget_dlock(ret);
	spin_unlock(&ret->d_lock);
	spin_unlock(&p->d_lock);
	spin_unlock(&autofs4_lock);

	dput(prev);

	return ret;
}

/*
 * Check a direct mount point for busyness.
 * Direct mounts have similar expiry semantics to tree mounts.
 * The tree is not busy iff no mountpoints are busy and there are no
 * autofs submounts.
 */
static int autofs4_direct_busy(struct vfsmount *mnt,
				struct dentry *top,
				unsigned long timeout,
				int do_now)
{
	DPRINTK("top %p %.*s",
		top, (int) top->d_name.len, top->d_name.name);

	/* If it's busy update the expiry counters */
	if (!may_umount_tree(mnt)) {
		struct autofs_info *ino = autofs4_dentry_ino(top);
		if (ino)
			ino->last_used = jiffies;
		return 1;
	}

	/* Timeout of a direct mount is determined by its top dentry */
	if (!autofs4_can_expire(top, timeout, do_now))
		return 1;

	return 0;
}

/* Check a directory tree of mount points for busyness
 * The tree is not busy iff no mountpoints are busy
 */
static int autofs4_tree_busy(struct vfsmount *mnt,
	       		     struct dentry *top,
			     unsigned long timeout,
			     int do_now)
{
	struct autofs_info *top_ino = autofs4_dentry_ino(top);
	struct dentry *p;

	DPRINTK("top %p %.*s",
		top, (int)top->d_name.len, top->d_name.name);

	/* Negative dentry - give up */
	if (!simple_positive(top))
		return 1;

	p = NULL;
	while ((p = get_next_positive_dentry(p, top))) {
		DPRINTK("dentry %p %.*s",
			p, (int) p->d_name.len, p->d_name.name);

		/*
		 * Is someone visiting anywhere in the subtree ?
		 * If there's no mount we need to check the usage
		 * count for the autofs dentry.
		 * If the fs is busy update the expiry counter.
		 */
		if (d_mountpoint(p)) {
			if (autofs4_mount_busy(mnt, p)) {
				top_ino->last_used = jiffies;
				dput(p);
				return 1;
			}
		} else {
			struct autofs_info *ino = autofs4_dentry_ino(p);
			unsigned int ino_count = atomic_read(&ino->count);

			/*
			 * Clean stale dentries below that have not been
			 * invalidated after a mount fail during lookup
			 */
			d_invalidate(p);

			/* allow for dget above and top is already dgot */
			if (p == top)
				ino_count += 2;
			else
				ino_count++;

			if (p->d_count > ino_count) {
				top_ino->last_used = jiffies;
				dput(p);
				return 1;
			}
		}
	}

	/* Timeout of a tree mount is ultimately determined by its top dentry */
	if (!autofs4_can_expire(top, timeout, do_now))
		return 1;

	return 0;
}

static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
					   struct dentry *parent,
					   unsigned long timeout,
					   int do_now)
{
	struct dentry *p;

	DPRINTK("parent %p %.*s",
		parent, (int)parent->d_name.len, parent->d_name.name);

	p = NULL;
	while ((p = get_next_positive_dentry(p, parent))) {
		DPRINTK("dentry %p %.*s",
			p, (int) p->d_name.len, p->d_name.name);

		if (d_mountpoint(p)) {
			/* Can we umount this guy */
			if (autofs4_mount_busy(mnt, p))
				continue;

			/* Can we expire this guy */
			if (autofs4_can_expire(p, timeout, do_now))
				return p;
		}
	}
	return NULL;
}

/* Check if we can expire a direct mount (possibly a tree) */
struct dentry *autofs4_expire_direct(struct super_block *sb,
				     struct vfsmount *mnt,
				     struct autofs_sb_info *sbi,
				     int how)
{
	unsigned long timeout;
	struct dentry *root = dget(sb->s_root);
	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	struct autofs_info *ino;

	if (!root)
		return NULL;

	now = jiffies;
	timeout = sbi->exp_timeout;

	spin_lock(&sbi->fs_lock);
	ino = autofs4_dentry_ino(root);
	/* No point expiring a pending mount */
	if (ino->flags & AUTOFS_INF_PENDING) {
		spin_unlock(&sbi->fs_lock);
		return NULL;
	}
	managed_dentry_set_transit(root);
	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
		struct autofs_info *ino = autofs4_dentry_ino(root);
		ino->flags |= AUTOFS_INF_EXPIRING;
		init_completion(&ino->expire_complete);
		spin_unlock(&sbi->fs_lock);
		return root;
	}
	managed_dentry_clear_transit(root);
	spin_unlock(&sbi->fs_lock);
	dput(root);

	return NULL;
}

/*
 * Find an eligible tree to time-out
 * A tree is eligible if :-
 *  - it is unused by any user process
 *  - it has been unused for exp_timeout time
 */
struct dentry *autofs4_expire_indirect(struct super_block *sb,
				       struct vfsmount *mnt,
				       struct autofs_sb_info *sbi,
				       int how)
{
	unsigned long timeout;
	struct dentry *root = sb->s_root;
	struct dentry *dentry;
	struct dentry *expired = NULL;
	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	int exp_leaves = how & AUTOFS_EXP_LEAVES;
	struct autofs_info *ino;
	unsigned int ino_count;

	if (!root)
		return NULL;

	now = jiffies;
	timeout = sbi->exp_timeout;

	dentry = NULL;
	while ((dentry = get_next_positive_dentry(dentry, root))) {
		spin_lock(&sbi->fs_lock);
		ino = autofs4_dentry_ino(dentry);
		/* No point expiring a pending mount */
		if (ino->flags & AUTOFS_INF_PENDING)
			goto cont;
		managed_dentry_set_transit(dentry);

		/*
		 * Case 1: (i) indirect mount or top level pseudo direct mount
		 *	   (autofs-4.1).
		 *	   (ii) indirect mount with offset mount, check the "/"
		 *	   offset (autofs-5.0+).
		 */
		if (d_mountpoint(dentry)) {
			DPRINTK("checking mountpoint %p %.*s",
				dentry, (int)dentry->d_name.len, dentry->d_name.name);

			/* Path walk currently on this dentry? */
			ino_count = atomic_read(&ino->count) + 2;
			if (dentry->d_count > ino_count)
				goto next;

			/* Can we umount this guy */
			if (autofs4_mount_busy(mnt, dentry))
				goto next;

			/* Can we expire this guy */
			if (autofs4_can_expire(dentry, timeout, do_now)) {
				expired = dentry;
				goto found;
			}
			goto next;
		}

		if (simple_empty(dentry))
			goto next;

		/* Case 2: tree mount, expire iff entire tree is not busy */
		if (!exp_leaves) {
			/* Path walk currently on this dentry? */
			ino_count = atomic_read(&ino->count) + 1;
			if (dentry->d_count > ino_count)
				goto next;

			if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
				expired = dentry;
				goto found;
			}
		/*
		 * Case 3: pseudo direct mount, expire individual leaves
		 *	   (autofs-4.1).
		 */
		} else {
			/* Path walk currently on this dentry? */
			ino_count = atomic_read(&ino->count) + 1;
			if (dentry->d_count > ino_count)
				goto next;

			expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
			if (expired) {
				dput(dentry);
				goto found;
			}
		}
next:
		managed_dentry_clear_transit(dentry);
cont:
		spin_unlock(&sbi->fs_lock);
	}
	return NULL;

found:
	DPRINTK("returning %p %.*s",
		expired, (int)expired->d_name.len, expired->d_name.name);
	ino = autofs4_dentry_ino(expired);
	ino->flags |= AUTOFS_INF_EXPIRING;
	init_completion(&ino->expire_complete);
	spin_unlock(&sbi->fs_lock);
	spin_lock(&autofs4_lock);
	spin_lock(&expired->d_parent->d_lock);
	spin_lock_nested(&expired->d_lock, DENTRY_D_LOCK_NESTED);
	list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
	spin_unlock(&expired->d_lock);
	spin_unlock(&expired->d_parent->d_lock);
	spin_unlock(&autofs4_lock);
	return expired;
}

int autofs4_expire_wait(struct dentry *dentry)
{
	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
	struct autofs_info *ino = autofs4_dentry_ino(dentry);
	int status;

	/* Block on any pending expire */
	spin_lock(&sbi->fs_lock);
	if (ino->flags & AUTOFS_INF_EXPIRING) {
		spin_unlock(&sbi->fs_lock);

		DPRINTK("waiting for expire %p name=%.*s",
			 dentry, dentry->d_name.len, dentry->d_name.name);

		status = autofs4_wait(sbi, dentry, NFY_NONE);
		wait_for_completion(&ino->expire_complete);

		DPRINTK("expire done status=%d", status);

		if (d_unhashed(dentry))
			return -EAGAIN;

		return status;
	}
	spin_unlock(&sbi->fs_lock);

	return 0;
}

/* Perform an expiry operation */
int autofs4_expire_run(struct super_block *sb,
		      struct vfsmount *mnt,
		      struct autofs_sb_info *sbi,
		      struct autofs_packet_expire __user *pkt_p)
{
	struct autofs_packet_expire pkt;
	struct autofs_info *ino;
	struct dentry *dentry;
	int ret = 0;

	memset(&pkt,0,sizeof pkt);

	pkt.hdr.proto_version = sbi->version;
	pkt.hdr.type = autofs_ptype_expire;

	if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
		return -EAGAIN;

	pkt.len = dentry->d_name.len;
	memcpy(pkt.name, dentry->d_name.name, pkt.len);
	pkt.name[pkt.len] = '\0';
	dput(dentry);

	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
		ret = -EFAULT;

	spin_lock(&sbi->fs_lock);
	ino = autofs4_dentry_ino(dentry);
	ino->flags &= ~AUTOFS_INF_EXPIRING;
	if (!d_unhashed(dentry))
		managed_dentry_clear_transit(dentry);
	complete_all(&ino->expire_complete);
	spin_unlock(&sbi->fs_lock);

	return ret;
}

int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
			    struct autofs_sb_info *sbi, int when)
{
	struct dentry *dentry;
	int ret = -EAGAIN;

	if (autofs_type_trigger(sbi->type))
		dentry = autofs4_expire_direct(sb, mnt, sbi, when);
	else
		dentry = autofs4_expire_indirect(sb, mnt, sbi, when);

	if (dentry) {
		struct autofs_info *ino = autofs4_dentry_ino(dentry);

		/* This is synchronous because it makes the daemon a
                   little easier */
		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);

		spin_lock(&sbi->fs_lock);
		ino->flags &= ~AUTOFS_INF_EXPIRING;
		spin_lock(&dentry->d_lock);
		if (ret)
			__managed_dentry_clear_transit(dentry);
		else {
			if ((IS_ROOT(dentry) ||
			    (autofs_type_indirect(sbi->type) &&
			     IS_ROOT(dentry->d_parent))) &&
			    !(dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
				__managed_dentry_set_automount(dentry);
		}
		spin_unlock(&dentry->d_lock);
		complete_all(&ino->expire_complete);
		spin_unlock(&sbi->fs_lock);
		dput(dentry);
	}

	return ret;
}

/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
   more to be done */
int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
			struct autofs_sb_info *sbi, int __user *arg)
{
	int do_now = 0;

	if (arg && get_user(do_now, arg))
		return -EFAULT;

	return autofs4_do_expire_multi(sb, mnt, sbi, do_now);
}
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
1da177e4 LT	29	if (!do_now) {
1da177e4 LT	30	/* Too young to die */
c0ba7e51	31	if (!timeout \|\| time_after(ino->last_used + timeout, now))
1da177e4 LT	32	return 0;
	33
	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 */
	38	ino->last_used = now;
	39	}
1da177e4 LT	40	return 1;
	41	}
	42
1f5f2c30 IK	43	/* Check a mount point for busyness */
1f5f2c30 IK	44	static int autofs4_mount_busy(struct vfsmount mnt, struct dentry dentry)
1da177e4	45	{
e0a7aae9	46	struct dentry *top = dentry;
9393bd07	47	struct path path = {.mnt = mnt, .dentry = dentry};
1f5f2c30	48	int status = 1;
1da177e4 LT	49
	50	DPRINTK("dentry %p %.*s",
	51	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	52
9393bd07	53	path_get(&path);
1da177e4	54
cc53ce53	55	if (!follow_down_one(&path))
1da177e4 LT	56	goto done;
1da177e4 LT	57
9393bd07 AV	58	if (is_autofs4_dentry(path.dentry)) {
9393bd07 AV	59	struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb);
bc9c4068 IK	60
bc9c4068 IK	61	/* This is an autofs submount, we can't expire it */
a92daf6b	62	if (autofs_type_indirect(sbi->type))
bc9c4068 IK	63	goto done;
	64
	65	/*
	66	* Otherwise it's an offset mount and we need to check
	67	* if we can umount its mount, if there is one.
	68	*/
9393bd07	69	if (!d_mountpoint(path.dentry)) {
a8985f3a	70	status = 0;
bc9c4068	71	goto done;
a8985f3a	72	}
bc9c4068	73	}
1da177e4	74
e0a7aae9	75	/* Update the expiry counter if fs is busy */
37d0892c	76	if (!may_umount_tree(path.mnt)) {
e0a7aae9 IK	77	struct autofs_info *ino = autofs4_dentry_ino(top);
	78	ino->last_used = jiffies;
	79	goto done;
	80	}
	81
	82	status = 0;
1da177e4 LT	83	done:
1da177e4 LT	84	DPRINTK("returning = %d", status);
9393bd07	85	path_put(&path);
1da177e4 LT	86	return status;
	87	}
	88
1ce12bad	89	/*
2fd6b7f5	90	* Calculate and dget next entry in top down tree traversal.
1ce12bad	91	*/
2fd6b7f5 NP	92	static struct dentry get_next_positive_dentry(struct dentry prev,
2fd6b7f5 NP	93	struct dentry *root)
1ce12bad	94	{
2fd6b7f5 NP	95	struct list_head *next;
	96	struct dentry p, ret;
	97
	98	if (prev == NULL)
	99	return dget(prev);
1ce12bad	100
b5c84bf6	101	spin_lock(&autofs4_lock);
2fd6b7f5 NP	102	relock:
	103	p = prev;
	104	spin_lock(&p->d_lock);
	105	again:
	106	next = p->d_subdirs.next;
1ce12bad IK	107	if (next == &p->d_subdirs) {
1ce12bad IK	108	while (1) {
2fd6b7f5 NP	109	struct dentry *parent;
	110
	111	if (p == root) {
	112	spin_unlock(&p->d_lock);
b5c84bf6	113	spin_unlock(&autofs4_lock);
2fd6b7f5	114	dput(prev);
1ce12bad	115	return NULL;
2fd6b7f5 NP	116	}
	117
	118	parent = p->d_parent;
	119	if (!spin_trylock(&parent->d_lock)) {
	120	spin_unlock(&p->d_lock);
	121	cpu_relax();
	122	goto relock;
	123	}
	124	spin_unlock(&p->d_lock);
1ce12bad	125	next = p->d_u.d_child.next;
2fd6b7f5 NP	126	p = parent;
2fd6b7f5 NP	127	if (next != &parent->d_subdirs)
1ce12bad	128	break;
1ce12bad IK	129	}
1ce12bad IK	130	}
2fd6b7f5 NP	131	ret = list_entry(next, struct dentry, d_u.d_child);
	132
	133	spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
	134	/* Negative dentry - try next */
	135	if (!simple_positive(ret)) {
	136	spin_unlock(&ret->d_lock);
	137	p = ret;
	138	goto again;
	139	}
	140	dget_dlock(ret);
	141	spin_unlock(&ret->d_lock);
	142	spin_unlock(&p->d_lock);
b5c84bf6	143	spin_unlock(&autofs4_lock);
2fd6b7f5 NP	144
	145	dput(prev);
	146
	147	return ret;
1ce12bad IK	148	}
1ce12bad IK	149
3a15e2ab IK	150	/*
	151	* Check a direct mount point for busyness.
	152	* Direct mounts have similar expiry semantics to tree mounts.
	153	* The tree is not busy iff no mountpoints are busy and there are no
	154	* autofs submounts.
	155	*/
	156	static int autofs4_direct_busy(struct vfsmount *mnt,
	157	struct dentry *top,
	158	unsigned long timeout,
	159	int do_now)
	160	{
	161	DPRINTK("top %p %.*s",
	162	top, (int) top->d_name.len, top->d_name.name);
	163
3a15e2ab IK	164	/* If it's busy update the expiry counters */
	165	if (!may_umount_tree(mnt)) {
	166	struct autofs_info *ino = autofs4_dentry_ino(top);
	167	if (ino)
	168	ino->last_used = jiffies;
	169	return 1;
	170	}
	171
	172	/* Timeout of a direct mount is determined by its top dentry */
	173	if (!autofs4_can_expire(top, timeout, do_now))
	174	return 1;
	175
	176	return 0;
	177	}
	178
1da177e4 LT	179	/* Check a directory tree of mount points for busyness
1da177e4 LT	180	* The tree is not busy iff no mountpoints are busy
1da177e4	181	*/
1f5f2c30 IK	182	static int autofs4_tree_busy(struct vfsmount *mnt,
	183	struct dentry *top,
	184	unsigned long timeout,
	185	int do_now)
1da177e4	186	{
e0a7aae9	187	struct autofs_info *top_ino = autofs4_dentry_ino(top);
1ce12bad	188	struct dentry *p;
1da177e4	189
1f5f2c30	190	DPRINTK("top %p %.*s",
1da177e4 LT	191	top, (int)top->d_name.len, top->d_name.name);
	192
	193	/* Negative dentry - give up */
	194	if (!simple_positive(top))
1f5f2c30	195	return 1;
1da177e4	196
2fd6b7f5 NP	197	p = NULL;
2fd6b7f5 NP	198	while ((p = get_next_positive_dentry(p, top))) {
1da177e4	199	DPRINTK("dentry %p %.*s",
1ce12bad	200	p, (int) p->d_name.len, p->d_name.name);
1da177e4	201
1aff3c8b IK	202	/*
	203	* Is someone visiting anywhere in the subtree ?
	204	* If there's no mount we need to check the usage
	205	* count for the autofs dentry.
e0a7aae9	206	* If the fs is busy update the expiry counter.
1aff3c8b	207	*/
1ce12bad	208	if (d_mountpoint(p)) {
1ce12bad	209	if (autofs4_mount_busy(mnt, p)) {
e0a7aae9	210	top_ino->last_used = jiffies;
1ce12bad	211	dput(p);
1f5f2c30	212	return 1;
1da177e4	213	}
1aff3c8b	214	} else {
e0a7aae9	215	struct autofs_info *ino = autofs4_dentry_ino(p);
1aff3c8b IK	216	unsigned int ino_count = atomic_read(&ino->count);
1aff3c8b IK	217
f9022f66 IK	218	/*
	219	* Clean stale dentries below that have not been
	220	* invalidated after a mount fail during lookup
	221	*/
	222	d_invalidate(p);
	223
1aff3c8b IK	224	/* allow for dget above and top is already dgot */
	225	if (p == top)
	226	ino_count += 2;
	227	else
	228	ino_count++;
	229
b7ab39f6	230	if (p->d_count > ino_count) {
e0a7aae9	231	top_ino->last_used = jiffies;
1aff3c8b IK	232	dput(p);
	233	return 1;
	234	}
1da177e4	235	}
1da177e4	236	}
1aff3c8b IK	237
	238	/* Timeout of a tree mount is ultimately determined by its top dentry */
	239	if (!autofs4_can_expire(top, timeout, do_now))
	240	return 1;
	241
1f5f2c30	242	return 0;
1da177e4 LT	243	}
	244
	245	static struct dentry autofs4_check_leaves(struct vfsmount mnt,
	246	struct dentry *parent,
	247	unsigned long timeout,
	248	int do_now)
	249	{
1ce12bad	250	struct dentry *p;
1da177e4 LT	251
	252	DPRINTK("parent %p %.*s",
	253	parent, (int)parent->d_name.len, parent->d_name.name);
	254
2fd6b7f5 NP	255	p = NULL;
2fd6b7f5 NP	256	while ((p = get_next_positive_dentry(p, parent))) {
1da177e4	257	DPRINTK("dentry %p %.*s",
1ce12bad	258	p, (int) p->d_name.len, p->d_name.name);
1da177e4	259
1ce12bad	260	if (d_mountpoint(p)) {
e0a7aae9 IK	261	/* Can we umount this guy */
e0a7aae9 IK	262	if (autofs4_mount_busy(mnt, p))
2fd6b7f5	263	continue;
1da177e4	264
e0a7aae9 IK	265	/* Can we expire this guy */
e0a7aae9 IK	266	if (autofs4_can_expire(p, timeout, do_now))
1ce12bad	267	return p;
1da177e4	268	}
1da177e4	269	}
1da177e4 LT	270	return NULL;
	271	}
	272
3a15e2ab	273	/* Check if we can expire a direct mount (possibly a tree) */
8d7b48e0 IK	274	struct dentry autofs4_expire_direct(struct super_block sb,
	275	struct vfsmount *mnt,
	276	struct autofs_sb_info *sbi,
	277	int how)
3a15e2ab IK	278	{
	279	unsigned long timeout;
	280	struct dentry *root = dget(sb->s_root);
	281	int do_now = how & AUTOFS_EXP_IMMEDIATE;
b5b80177	282	struct autofs_info *ino;
3a15e2ab	283
c0ba7e51	284	if (!root)
3a15e2ab IK	285	return NULL;
	286
	287	now = jiffies;
	288	timeout = sbi->exp_timeout;
	289
3a15e2ab	290	spin_lock(&sbi->fs_lock);
b5b80177 IK	291	ino = autofs4_dentry_ino(root);
	292	/* No point expiring a pending mount */
	293	if (ino->flags & AUTOFS_INF_PENDING) {
	294	spin_unlock(&sbi->fs_lock);
	295	return NULL;
	296	}
	297	managed_dentry_set_transit(root);
3a15e2ab IK	298	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
3a15e2ab IK	299	struct autofs_info *ino = autofs4_dentry_ino(root);
3a15e2ab	300	ino->flags \|= AUTOFS_INF_EXPIRING;
6e60a9ab	301	init_completion(&ino->expire_complete);
3a15e2ab IK	302	spin_unlock(&sbi->fs_lock);
	303	return root;
	304	}
b5b80177	305	managed_dentry_clear_transit(root);
3a15e2ab IK	306	spin_unlock(&sbi->fs_lock);
	307	dput(root);
	308
	309	return NULL;
	310	}
	311
1da177e4 LT	312	/*
	313	* Find an eligible tree to time-out
	314	* A tree is eligible if :-
	315	* - it is unused by any user process
	316	* - it has been unused for exp_timeout time
	317	*/
8d7b48e0 IK	318	struct dentry autofs4_expire_indirect(struct super_block sb,
	319	struct vfsmount *mnt,
	320	struct autofs_sb_info *sbi,
	321	int how)
1da177e4 LT	322	{
	323	unsigned long timeout;
	324	struct dentry *root = sb->s_root;
2fd6b7f5	325	struct dentry *dentry;
1da177e4	326	struct dentry *expired = NULL;
1da177e4 LT	327	int do_now = how & AUTOFS_EXP_IMMEDIATE;
1da177e4 LT	328	int exp_leaves = how & AUTOFS_EXP_LEAVES;
97e7449a IK	329	struct autofs_info *ino;
97e7449a IK	330	unsigned int ino_count;
1da177e4	331
c0ba7e51	332	if (!root)
1da177e4 LT	333	return NULL;
	334
	335	now = jiffies;
	336	timeout = sbi->exp_timeout;
	337
2fd6b7f5 NP	338	dentry = NULL;
2fd6b7f5 NP	339	while ((dentry = get_next_positive_dentry(dentry, root))) {
97e7449a IK	340	spin_lock(&sbi->fs_lock);
97e7449a IK	341	ino = autofs4_dentry_ino(dentry);
b5b80177 IK	342	/* No point expiring a pending mount */
	343	if (ino->flags & AUTOFS_INF_PENDING)
	344	goto cont;
	345	managed_dentry_set_transit(dentry);
97e7449a	346
3a15e2ab IK	347	/*
	348	* Case 1: (i) indirect mount or top level pseudo direct mount
	349	* (autofs-4.1).
	350	* (ii) indirect mount with offset mount, check the "/"
	351	* offset (autofs-5.0+).
	352	*/
1da177e4 LT	353	if (d_mountpoint(dentry)) {
	354	DPRINTK("checking mountpoint %p %.*s",
	355	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	356
97e7449a IK	357	/* Path walk currently on this dentry? */
97e7449a IK	358	ino_count = atomic_read(&ino->count) + 2;
b7ab39f6	359	if (dentry->d_count > ino_count)
97e7449a IK	360	goto next;
97e7449a IK	361
e0a7aae9 IK	362	/* Can we umount this guy */
e0a7aae9 IK	363	if (autofs4_mount_busy(mnt, dentry))
1da177e4 LT	364	goto next;
1da177e4 LT	365
e0a7aae9 IK	366	/* Can we expire this guy */
e0a7aae9 IK	367	if (autofs4_can_expire(dentry, timeout, do_now)) {
1da177e4	368	expired = dentry;
afec570c	369	goto found;
1da177e4 LT	370	}
	371	goto next;
	372	}
	373
1f5f2c30	374	if (simple_empty(dentry))
1da177e4 LT	375	goto next;
	376
	377	/* Case 2: tree mount, expire iff entire tree is not busy */
	378	if (!exp_leaves) {
97e7449a IK	379	/* Path walk currently on this dentry? */
97e7449a IK	380	ino_count = atomic_read(&ino->count) + 1;
b7ab39f6	381	if (dentry->d_count > ino_count)
97e7449a	382	goto next;
3a9720ce	383
97e7449a	384	if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
3a9720ce	385	expired = dentry;
afec570c	386	goto found;
1da177e4	387	}
3a15e2ab IK	388	/*
	389	* Case 3: pseudo direct mount, expire individual leaves
	390	* (autofs-4.1).
	391	*/
1da177e4	392	} else {
97e7449a IK	393	/* Path walk currently on this dentry? */
97e7449a IK	394	ino_count = atomic_read(&ino->count) + 1;
b7ab39f6	395	if (dentry->d_count > ino_count)
97e7449a IK	396	goto next;
97e7449a IK	397
1da177e4 LT	398	expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
	399	if (expired) {
	400	dput(dentry);
afec570c	401	goto found;
1da177e4 LT	402	}
	403	}
	404	next:
b5b80177 IK	405	managed_dentry_clear_transit(dentry);
b5b80177 IK	406	cont:
97e7449a	407	spin_unlock(&sbi->fs_lock);
1da177e4	408	}
1da177e4	409	return NULL;
afec570c IK	410
	411	found:
	412	DPRINTK("returning %p %.*s",
	413	expired, (int)expired->d_name.len, expired->d_name.name);
97e7449a IK	414	ino = autofs4_dentry_ino(expired);
97e7449a IK	415	ino->flags \|= AUTOFS_INF_EXPIRING;
6e60a9ab	416	init_completion(&ino->expire_complete);
97e7449a	417	spin_unlock(&sbi->fs_lock);
b5c84bf6	418	spin_lock(&autofs4_lock);
2fd6b7f5 NP	419	spin_lock(&expired->d_parent->d_lock);
2fd6b7f5 NP	420	spin_lock_nested(&expired->d_lock, DENTRY_D_LOCK_NESTED);
afec570c	421	list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
2fd6b7f5 NP	422	spin_unlock(&expired->d_lock);
2fd6b7f5 NP	423	spin_unlock(&expired->d_parent->d_lock);
b5c84bf6	424	spin_unlock(&autofs4_lock);
afec570c	425	return expired;
1da177e4 LT	426	}
1da177e4 LT	427
06a35985 IK	428	int autofs4_expire_wait(struct dentry *dentry)
	429	{
	430	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
	431	struct autofs_info *ino = autofs4_dentry_ino(dentry);
	432	int status;
	433
	434	/* Block on any pending expire */
	435	spin_lock(&sbi->fs_lock);
	436	if (ino->flags & AUTOFS_INF_EXPIRING) {
	437	spin_unlock(&sbi->fs_lock);
	438
	439	DPRINTK("waiting for expire %p name=%.*s",
	440	dentry, dentry->d_name.len, dentry->d_name.name);
	441
	442	status = autofs4_wait(sbi, dentry, NFY_NONE);
	443	wait_for_completion(&ino->expire_complete);
	444
	445	DPRINTK("expire done status=%d", status);
	446
4b1ae27a	447	if (d_unhashed(dentry))
06a35985 IK	448	return -EAGAIN;
	449
	450	return status;
	451	}
	452	spin_unlock(&sbi->fs_lock);
	453
	454	return 0;
	455	}
	456
1da177e4 LT	457	/* Perform an expiry operation */
	458	int autofs4_expire_run(struct super_block *sb,
	459	struct vfsmount *mnt,
	460	struct autofs_sb_info *sbi,
	461	struct autofs_packet_expire __user *pkt_p)
	462	{
	463	struct autofs_packet_expire pkt;
97e7449a	464	struct autofs_info *ino;
1da177e4	465	struct dentry *dentry;
97e7449a	466	int ret = 0;
1da177e4 LT	467
	468	memset(&pkt,0,sizeof pkt);
	469
	470	pkt.hdr.proto_version = sbi->version;
	471	pkt.hdr.type = autofs_ptype_expire;
	472
3a15e2ab	473	if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
1da177e4 LT	474	return -EAGAIN;
	475
	476	pkt.len = dentry->d_name.len;
	477	memcpy(pkt.name, dentry->d_name.name, pkt.len);
	478	pkt.name[pkt.len] = '\0';
	479	dput(dentry);
	480
	481	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
97e7449a	482	ret = -EFAULT;
1da177e4	483
97e7449a IK	484	spin_lock(&sbi->fs_lock);
	485	ino = autofs4_dentry_ino(dentry);
	486	ino->flags &= ~AUTOFS_INF_EXPIRING;
10584211	487	if (!d_unhashed(dentry))
b5b80177	488	managed_dentry_clear_transit(dentry);
6e60a9ab	489	complete_all(&ino->expire_complete);
97e7449a IK	490	spin_unlock(&sbi->fs_lock);
	491
	492	return ret;
1da177e4 LT	493	}
1da177e4 LT	494
56fcef75 IK	495	int autofs4_do_expire_multi(struct super_block sb, struct vfsmount mnt,
56fcef75 IK	496	struct autofs_sb_info *sbi, int when)
1da177e4 LT	497	{
	498	struct dentry *dentry;
	499	int ret = -EAGAIN;
1da177e4	500
a92daf6b	501	if (autofs_type_trigger(sbi->type))
56fcef75	502	dentry = autofs4_expire_direct(sb, mnt, sbi, when);
3a15e2ab	503	else
56fcef75	504	dentry = autofs4_expire_indirect(sb, mnt, sbi, when);
3a15e2ab IK	505
3a15e2ab IK	506	if (dentry) {
1f5f2c30	507	struct autofs_info *ino = autofs4_dentry_ino(dentry);
1da177e4 LT	508
	509	/* This is synchronous because it makes the daemon a
	510	little easier */
1da177e4	511	ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
6e60a9ab	512
97e7449a	513	spin_lock(&sbi->fs_lock);
1f5f2c30	514	ino->flags &= ~AUTOFS_INF_EXPIRING;
b5b80177	515	spin_lock(&dentry->d_lock);
10584211	516	if (ret)
b5b80177 IK	517	__managed_dentry_clear_transit(dentry);
	518	else {
	519	if ((IS_ROOT(dentry) \|\|
	520	(autofs_type_indirect(sbi->type) &&
	521	IS_ROOT(dentry->d_parent))) &&
	522	!(dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
	523	__managed_dentry_set_automount(dentry);
	524	}
	525	spin_unlock(&dentry->d_lock);
6e60a9ab	526	complete_all(&ino->expire_complete);
97e7449a	527	spin_unlock(&sbi->fs_lock);
1da177e4 LT	528	dput(dentry);
1da177e4 LT	529	}
1f5f2c30	530
1da177e4 LT	531	return ret;
	532	}
	533
56fcef75 IK	534	/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
	535	more to be done */
	536	int autofs4_expire_multi(struct super_block sb, struct vfsmount mnt,
	537	struct autofs_sb_info sbi, int __user arg)
	538	{
	539	int do_now = 0;
	540
	541	if (arg && get_user(do_now, arg))
	542	return -EFAULT;
	543
	544	return autofs4_do_expire_multi(sb, mnt, sbi, do_now);
	545	}
	546