[linux-2.6-block.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;

	/* No point expiring a pending mount */
	if (dentry->d_flags & DCACHE_AUTOFS_PENDING)
		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;
	int status = 1;

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

	mntget(mnt);
	dget(dentry);

	if (!autofs4_follow_mount(&mnt, &dentry))
		goto done;

	/* This is an autofs submount, we can't expire it */
	if (is_autofs4_dentry(dentry))
		goto done;

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

	status = 0;
done:
	DPRINTK("returning = %d", status);
	dput(dentry);
	mntput(mnt);
	return status;
}

/*
 * Calculate next entry in top down tree traversal.
 * From next_mnt in namespace.c - elegant.
 */
static struct dentry *next_dentry(struct dentry *p, struct dentry *root)
{
	struct list_head *next = p->d_subdirs.next;

	if (next == &p->d_subdirs) {
		while (1) {
			if (p == root)
				return NULL;
			next = p->d_u.d_child.next;
			if (next != &p->d_parent->d_subdirs)
				break;
			p = p->d_parent;
		}
	}
	return list_entry(next, struct dentry, d_u.d_child);
}

/*
 * 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;

	spin_lock(&dcache_lock);
	for (p = top; p; p = next_dentry(p, top)) {
		/* Negative dentry - give up */
		if (!simple_positive(p))
			continue;

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

		p = dget(p);
		spin_unlock(&dcache_lock);

		/*
		 * 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 (atomic_read(&p->d_count) > ino_count) {
				top_ino->last_used = jiffies;
				dput(p);
				return 1;
			}
		}
		dput(p);
		spin_lock(&dcache_lock);
	}
	spin_unlock(&dcache_lock);

	/* 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);

	spin_lock(&dcache_lock);
	for (p = parent; p; p = next_dentry(p, parent)) {
		/* Negative dentry - give up */
		if (!simple_positive(p))
			continue;

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

		p = dget(p);
		spin_unlock(&dcache_lock);

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

			/* Can we expire this guy */
			if (autofs4_can_expire(p, timeout, do_now))
				return p;
		}
cont:
		dput(p);
		spin_lock(&dcache_lock);
	}
	spin_unlock(&dcache_lock);
	return NULL;
}

/* Check if we can expire a direct mount (possibly a tree) */
static 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;

	if (!root)
		return NULL;

	now = jiffies;
	timeout = sbi->exp_timeout;

	spin_lock(&sbi->fs_lock);
	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
		struct autofs_info *ino = autofs4_dentry_ino(root);
		if (d_mountpoint(root)) {
			ino->flags |= AUTOFS_INF_MOUNTPOINT;
			root->d_mounted--;
		}
		ino->flags |= AUTOFS_INF_EXPIRING;
		init_completion(&ino->expire_complete);
		spin_unlock(&sbi->fs_lock);
		return 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
 */
static 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 *expired = NULL;
	struct list_head *next;
	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;

	spin_lock(&dcache_lock);
	next = root->d_subdirs.next;

	/* On exit from the loop expire is set to a dgot dentry
	 * to expire or it's NULL */
	while ( next != &root->d_subdirs ) {
		struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);

		/* Negative dentry - give up */
		if (!simple_positive(dentry)) {
			next = next->next;
			continue;
		}

		dentry = dget(dentry);
		spin_unlock(&dcache_lock);

		spin_lock(&sbi->fs_lock);
		ino = autofs4_dentry_ino(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 (atomic_read(&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 (atomic_read(&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 (atomic_read(&dentry->d_count) > ino_count)
				goto next;

			expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
			if (expired) {
				dput(dentry);
				goto found;
			}
		}
next:
		spin_unlock(&sbi->fs_lock);
		dput(dentry);
		spin_lock(&dcache_lock);
		next = next->next;
	}
	spin_unlock(&dcache_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(&dcache_lock);
	list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
	spin_unlock(&dcache_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;
	complete_all(&ino->expire_complete);
	spin_unlock(&sbi->fs_lock);

	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)
{
	struct dentry *dentry;
	int ret = -EAGAIN;
	int do_now = 0;

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

	if (sbi->type & AUTOFS_TYPE_TRIGGER)
		dentry = autofs4_expire_direct(sb, mnt, sbi, do_now);
	else
		dentry = autofs4_expire_indirect(sb, mnt, sbi, do_now);

	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);
		if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
			sb->s_root->d_mounted++;
			ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
		}
		ino->flags &= ~AUTOFS_INF_EXPIRING;
		complete_all(&ino->expire_complete);
		spin_unlock(&sbi->fs_lock);
		dput(dentry);
	}

	return ret;
}
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 */
c0ba7e51	35	if (!timeout \|\| time_after(ino->last_used + timeout, now))
1da177e4 LT	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 */
1f5f2c30 IK	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;
1da177e4 LT	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:
1da177e4 LT	75	DPRINTK("returning = %d", status);
1da177e4	76	dput(dentry);
868eb7a8	77	mntput(mnt);
1da177e4 LT	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
1da177e4 LT	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
1da177e4 LT	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);
1da177e4 LT	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);
1aff3c8b IK	176
f9022f66 IK	177	/*
	178	* Clean stale dentries below that have not been
	179	* invalidated after a mount fail during lookup
	180	*/
	181	d_invalidate(p);
	182
1aff3c8b IK	183	/* allow for dget above and top is already dgot */
	184	if (p == top)
	185	ino_count += 2;
	186	else
	187	ino_count++;
	188
	189	if (atomic_read(&p->d_count) > ino_count) {
e0a7aae9	190	top_ino->last_used = jiffies;
1aff3c8b IK	191	dput(p);
	192	return 1;
	193	}
1da177e4	194	}
1ce12bad	195	dput(p);
1da177e4	196	spin_lock(&dcache_lock);
1da177e4 LT	197	}
1da177e4 LT	198	spin_unlock(&dcache_lock);
1aff3c8b IK	199
	200	/* Timeout of a tree mount is ultimately determined by its top dentry */
	201	if (!autofs4_can_expire(top, timeout, do_now))
	202	return 1;
	203
1f5f2c30	204	return 0;
1da177e4 LT	205	}
	206
	207	static struct dentry autofs4_check_leaves(struct vfsmount mnt,
	208	struct dentry *parent,
	209	unsigned long timeout,
	210	int do_now)
	211	{
1ce12bad	212	struct dentry *p;
1da177e4 LT	213
	214	DPRINTK("parent %p %.*s",
	215	parent, (int)parent->d_name.len, parent->d_name.name);
	216
	217	spin_lock(&dcache_lock);
1ce12bad	218	for (p = parent; p; p = next_dentry(p, parent)) {
1da177e4	219	/* Negative dentry - give up */
1ce12bad	220	if (!simple_positive(p))
1da177e4	221	continue;
1da177e4 LT	222
1da177e4 LT	223	DPRINTK("dentry %p %.*s",
1ce12bad	224	p, (int) p->d_name.len, p->d_name.name);
1da177e4	225
1ce12bad	226	p = dget(p);
1da177e4 LT	227	spin_unlock(&dcache_lock);
1da177e4 LT	228
1ce12bad	229	if (d_mountpoint(p)) {
e0a7aae9 IK	230	/* Can we umount this guy */
e0a7aae9 IK	231	if (autofs4_mount_busy(mnt, p))
1da177e4 LT	232	goto cont;
1da177e4 LT	233
e0a7aae9 IK	234	/* Can we expire this guy */
e0a7aae9 IK	235	if (autofs4_can_expire(p, timeout, do_now))
1ce12bad	236	return p;
1da177e4 LT	237	}
1da177e4 LT	238	cont:
1ce12bad	239	dput(p);
1da177e4	240	spin_lock(&dcache_lock);
1da177e4 LT	241	}
1da177e4 LT	242	spin_unlock(&dcache_lock);
1da177e4 LT	243	return NULL;
	244	}
	245
3a15e2ab IK	246	/* Check if we can expire a direct mount (possibly a tree) */
	247	static struct dentry autofs4_expire_direct(struct super_block sb,
	248	struct vfsmount *mnt,
	249	struct autofs_sb_info *sbi,
	250	int how)
	251	{
	252	unsigned long timeout;
	253	struct dentry *root = dget(sb->s_root);
	254	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	255
c0ba7e51	256	if (!root)
3a15e2ab IK	257	return NULL;
	258
	259	now = jiffies;
	260	timeout = sbi->exp_timeout;
	261
3a15e2ab IK	262	spin_lock(&sbi->fs_lock);
	263	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
	264	struct autofs_info *ino = autofs4_dentry_ino(root);
6e60a9ab IK	265	if (d_mountpoint(root)) {
	266	ino->flags \|= AUTOFS_INF_MOUNTPOINT;
	267	root->d_mounted--;
	268	}
3a15e2ab	269	ino->flags \|= AUTOFS_INF_EXPIRING;
6e60a9ab	270	init_completion(&ino->expire_complete);
3a15e2ab IK	271	spin_unlock(&sbi->fs_lock);
	272	return root;
	273	}
	274	spin_unlock(&sbi->fs_lock);
	275	dput(root);
	276
	277	return NULL;
	278	}
	279
1da177e4 LT	280	/*
	281	* Find an eligible tree to time-out
	282	* A tree is eligible if :-
	283	* - it is unused by any user process
	284	* - it has been unused for exp_timeout time
	285	*/
3a15e2ab IK	286	static struct dentry autofs4_expire_indirect(struct super_block sb,
	287	struct vfsmount *mnt,
	288	struct autofs_sb_info *sbi,
	289	int how)
1da177e4 LT	290	{
	291	unsigned long timeout;
	292	struct dentry *root = sb->s_root;
	293	struct dentry *expired = NULL;
	294	struct list_head *next;
	295	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	296	int exp_leaves = how & AUTOFS_EXP_LEAVES;
97e7449a IK	297	struct autofs_info *ino;
97e7449a IK	298	unsigned int ino_count;
1da177e4	299
c0ba7e51	300	if (!root)
1da177e4 LT	301	return NULL;
	302
	303	now = jiffies;
	304	timeout = sbi->exp_timeout;
	305
	306	spin_lock(&dcache_lock);
	307	next = root->d_subdirs.next;
	308
	309	/* On exit from the loop expire is set to a dgot dentry
	310	* to expire or it's NULL */
	311	while ( next != &root->d_subdirs ) {
5160ee6f	312	struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
1da177e4 LT	313
1da177e4 LT	314	/* Negative dentry - give up */
1f5f2c30	315	if (!simple_positive(dentry)) {
1da177e4 LT	316	next = next->next;
	317	continue;
	318	}
	319
	320	dentry = dget(dentry);
	321	spin_unlock(&dcache_lock);
	322
97e7449a IK	323	spin_lock(&sbi->fs_lock);
	324	ino = autofs4_dentry_ino(dentry);
	325
3a15e2ab IK	326	/*
	327	* Case 1: (i) indirect mount or top level pseudo direct mount
	328	* (autofs-4.1).
	329	* (ii) indirect mount with offset mount, check the "/"
	330	* offset (autofs-5.0+).
	331	*/
1da177e4 LT	332	if (d_mountpoint(dentry)) {
	333	DPRINTK("checking mountpoint %p %.*s",
	334	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	335
97e7449a IK	336	/* Path walk currently on this dentry? */
	337	ino_count = atomic_read(&ino->count) + 2;
	338	if (atomic_read(&dentry->d_count) > ino_count)
	339	goto next;
	340
e0a7aae9 IK	341	/* Can we umount this guy */
e0a7aae9 IK	342	if (autofs4_mount_busy(mnt, dentry))
1da177e4 LT	343	goto next;
1da177e4 LT	344
e0a7aae9 IK	345	/* Can we expire this guy */
e0a7aae9 IK	346	if (autofs4_can_expire(dentry, timeout, do_now)) {
1da177e4	347	expired = dentry;
afec570c	348	goto found;
1da177e4 LT	349	}
	350	goto next;
	351	}
	352
1f5f2c30	353	if (simple_empty(dentry))
1da177e4 LT	354	goto next;
	355
	356	/* Case 2: tree mount, expire iff entire tree is not busy */
	357	if (!exp_leaves) {
97e7449a IK	358	/* Path walk currently on this dentry? */
	359	ino_count = atomic_read(&ino->count) + 1;
	360	if (atomic_read(&dentry->d_count) > ino_count)
	361	goto next;
3a9720ce	362
97e7449a	363	if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
3a9720ce	364	expired = dentry;
afec570c	365	goto found;
1da177e4	366	}
3a15e2ab IK	367	/*
	368	* Case 3: pseudo direct mount, expire individual leaves
	369	* (autofs-4.1).
	370	*/
1da177e4	371	} else {
97e7449a IK	372	/* Path walk currently on this dentry? */
	373	ino_count = atomic_read(&ino->count) + 1;
	374	if (atomic_read(&dentry->d_count) > ino_count)
	375	goto next;
	376
1da177e4 LT	377	expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
	378	if (expired) {
	379	dput(dentry);
afec570c	380	goto found;
1da177e4 LT	381	}
	382	}
	383	next:
97e7449a	384	spin_unlock(&sbi->fs_lock);
1da177e4 LT	385	dput(dentry);
	386	spin_lock(&dcache_lock);
	387	next = next->next;
	388	}
1da177e4	389	spin_unlock(&dcache_lock);
1da177e4	390	return NULL;
afec570c IK	391
	392	found:
	393	DPRINTK("returning %p %.*s",
	394	expired, (int)expired->d_name.len, expired->d_name.name);
97e7449a IK	395	ino = autofs4_dentry_ino(expired);
97e7449a IK	396	ino->flags \|= AUTOFS_INF_EXPIRING;
6e60a9ab	397	init_completion(&ino->expire_complete);
97e7449a	398	spin_unlock(&sbi->fs_lock);
afec570c IK	399	spin_lock(&dcache_lock);
	400	list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
	401	spin_unlock(&dcache_lock);
	402	return expired;
1da177e4 LT	403	}
1da177e4 LT	404
06a35985 IK	405	int autofs4_expire_wait(struct dentry *dentry)
	406	{
	407	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
	408	struct autofs_info *ino = autofs4_dentry_ino(dentry);
	409	int status;
	410
	411	/* Block on any pending expire */
	412	spin_lock(&sbi->fs_lock);
	413	if (ino->flags & AUTOFS_INF_EXPIRING) {
	414	spin_unlock(&sbi->fs_lock);
	415
	416	DPRINTK("waiting for expire %p name=%.*s",
	417	dentry, dentry->d_name.len, dentry->d_name.name);
	418
	419	status = autofs4_wait(sbi, dentry, NFY_NONE);
	420	wait_for_completion(&ino->expire_complete);
	421
	422	DPRINTK("expire done status=%d", status);
	423
	424	if (d_unhashed(dentry))
	425	return -EAGAIN;
	426
	427	return status;
	428	}
	429	spin_unlock(&sbi->fs_lock);
	430
	431	return 0;
	432	}
	433
1da177e4 LT	434	/* Perform an expiry operation */
	435	int autofs4_expire_run(struct super_block *sb,
	436	struct vfsmount *mnt,
	437	struct autofs_sb_info *sbi,
	438	struct autofs_packet_expire __user *pkt_p)
	439	{
	440	struct autofs_packet_expire pkt;
97e7449a	441	struct autofs_info *ino;
1da177e4	442	struct dentry *dentry;
97e7449a	443	int ret = 0;
1da177e4 LT	444
	445	memset(&pkt,0,sizeof pkt);
	446
	447	pkt.hdr.proto_version = sbi->version;
	448	pkt.hdr.type = autofs_ptype_expire;
	449
3a15e2ab	450	if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
1da177e4 LT	451	return -EAGAIN;
	452
	453	pkt.len = dentry->d_name.len;
	454	memcpy(pkt.name, dentry->d_name.name, pkt.len);
	455	pkt.name[pkt.len] = '\0';
	456	dput(dentry);
	457
	458	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
97e7449a	459	ret = -EFAULT;
1da177e4	460
97e7449a IK	461	spin_lock(&sbi->fs_lock);
	462	ino = autofs4_dentry_ino(dentry);
	463	ino->flags &= ~AUTOFS_INF_EXPIRING;
6e60a9ab	464	complete_all(&ino->expire_complete);
97e7449a IK	465	spin_unlock(&sbi->fs_lock);
	466
	467	return ret;
1da177e4 LT	468	}
	469
	470	/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
	471	more to be done */
	472	int autofs4_expire_multi(struct super_block sb, struct vfsmount mnt,
	473	struct autofs_sb_info sbi, int __user arg)
	474	{
	475	struct dentry *dentry;
	476	int ret = -EAGAIN;
	477	int do_now = 0;
	478
	479	if (arg && get_user(do_now, arg))
	480	return -EFAULT;
	481
bb979d7f	482	if (sbi->type & AUTOFS_TYPE_TRIGGER)
3a15e2ab IK	483	dentry = autofs4_expire_direct(sb, mnt, sbi, do_now);
	484	else
	485	dentry = autofs4_expire_indirect(sb, mnt, sbi, do_now);
	486
	487	if (dentry) {
1f5f2c30	488	struct autofs_info *ino = autofs4_dentry_ino(dentry);
1da177e4 LT	489
	490	/* This is synchronous because it makes the daemon a
	491	little easier */
1da177e4	492	ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
6e60a9ab	493
97e7449a	494	spin_lock(&sbi->fs_lock);
6e60a9ab IK	495	if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
	496	sb->s_root->d_mounted++;
	497	ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
	498	}
1f5f2c30	499	ino->flags &= ~AUTOFS_INF_EXPIRING;
6e60a9ab	500	complete_all(&ino->expire_complete);
97e7449a	501	spin_unlock(&sbi->fs_lock);
1da177e4 LT	502	dput(dentry);
1da177e4 LT	503	}
1f5f2c30	504
1da177e4 LT	505	return ret;
	506	}
	507