[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;

	/* No point expiring a pending mount */
	if (dentry->d_flags & DCACHE_AUTOFS_PENDING)
		return 0;

	if (!do_now) {
		/* Too young to die */
		if (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);
	mntput(mnt);
	dput(dentry);
	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);

	/* Not a mountpoint - give up */
	if (!d_mountpoint(top))
		return 1;

	/* 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);

			/* 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 (!sbi->exp_timeout || !root)
		return NULL;

	now = jiffies;
	timeout = sbi->exp_timeout;

	/* Lock the tree as we must expire as a whole */
	spin_lock(&sbi->fs_lock);
	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
		struct autofs_info *ino = autofs4_dentry_ino(root);

		/* Set this flag early to catch sys_chdir and the like */
		ino->flags |= AUTOFS_INF_EXPIRING;
		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;

	if ( !sbi->exp_timeout || !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);

		/*
		 * 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);

			/* 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;
				break;
			}
			goto next;
		}

		if (simple_empty(dentry))
			goto next;

		/* Case 2: tree mount, expire iff entire tree is not busy */
		if (!exp_leaves) {
			/* Lock the tree as we must expire as a whole */
			spin_lock(&sbi->fs_lock);
			if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
				struct autofs_info *inf = autofs4_dentry_ino(dentry);

				/* Set this flag early to catch sys_chdir and the like */
				inf->flags |= AUTOFS_INF_EXPIRING;
				spin_unlock(&sbi->fs_lock);
				expired = dentry;
				break;
			}
			spin_unlock(&sbi->fs_lock);
		/*
		 * Case 3: pseudo direct mount, expire individual leaves
		 *	   (autofs-4.1).
		 */
		} else {
			expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
			if (expired) {
				dput(dentry);
				break;
			}
		}
next:
		dput(dentry);
		spin_lock(&dcache_lock);
		next = next->next;
	}

	if (expired) {
		DPRINTK("returning %p %.*s",
			expired, (int)expired->d_name.len, expired->d_name.name);
		spin_lock(&dcache_lock);
		list_del(&expired->d_parent->d_subdirs);
		list_add(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
		spin_unlock(&dcache_lock);
		return expired;
	}
	spin_unlock(&dcache_lock);

	return NULL;
}

/* 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 dentry *dentry;

	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)) )
		return -EFAULT;

	return 0;
}

/* 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_DIRECT)
		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 */
		ino->flags |= AUTOFS_INF_EXPIRING;
		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
		ino->flags &= ~AUTOFS_INF_EXPIRING;
		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 */
	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	}
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:
	75	DPRINTK("returning = %d", status);
	76	mntput(mnt);
	77	dput(dentry);
	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
	116	/* Not a mountpoint - give up */
	117	if (!d_mountpoint(top))
	118	return 1;
	119
	120	/* If it's busy update the expiry counters */
	121	if (!may_umount_tree(mnt)) {
	122	struct autofs_info *ino = autofs4_dentry_ino(top);
	123	if (ino)
	124	ino->last_used = jiffies;
	125	return 1;
	126	}
	127
	128	/* Timeout of a direct mount is determined by its top dentry */
	129	if (!autofs4_can_expire(top, timeout, do_now))
	130	return 1;
	131
	132	return 0;
	133	}
	134
1da177e4 LT	135	/* Check a directory tree of mount points for busyness
1da177e4 LT	136	* The tree is not busy iff no mountpoints are busy
1da177e4	137	*/
1f5f2c30 IK	138	static int autofs4_tree_busy(struct vfsmount *mnt,
	139	struct dentry *top,
	140	unsigned long timeout,
	141	int do_now)
1da177e4	142	{
e0a7aae9	143	struct autofs_info *top_ino = autofs4_dentry_ino(top);
1ce12bad	144	struct dentry *p;
1da177e4	145
1f5f2c30	146	DPRINTK("top %p %.*s",
1da177e4 LT	147	top, (int)top->d_name.len, top->d_name.name);
	148
	149	/* Negative dentry - give up */
	150	if (!simple_positive(top))
1f5f2c30	151	return 1;
1da177e4	152
1da177e4	153	spin_lock(&dcache_lock);
1ce12bad	154	for (p = top; p; p = next_dentry(p, top)) {
1da177e4	155	/* Negative dentry - give up */
1ce12bad	156	if (!simple_positive(p))
1da177e4	157	continue;
1da177e4 LT	158
1da177e4 LT	159	DPRINTK("dentry %p %.*s",
1ce12bad	160	p, (int) p->d_name.len, p->d_name.name);
1da177e4	161
1ce12bad	162	p = dget(p);
1da177e4 LT	163	spin_unlock(&dcache_lock);
1da177e4 LT	164
1aff3c8b IK	165	/*
	166	* Is someone visiting anywhere in the subtree ?
	167	* If there's no mount we need to check the usage
	168	* count for the autofs dentry.
e0a7aae9	169	* If the fs is busy update the expiry counter.
1aff3c8b	170	*/
1ce12bad	171	if (d_mountpoint(p)) {
1ce12bad	172	if (autofs4_mount_busy(mnt, p)) {
e0a7aae9	173	top_ino->last_used = jiffies;
1ce12bad	174	dput(p);
1f5f2c30	175	return 1;
1da177e4	176	}
1aff3c8b	177	} else {
e0a7aae9	178	struct autofs_info *ino = autofs4_dentry_ino(p);
1aff3c8b IK	179	unsigned int ino_count = atomic_read(&ino->count);
	180
	181	/* allow for dget above and top is already dgot */
	182	if (p == top)
	183	ino_count += 2;
	184	else
	185	ino_count++;
	186
	187	if (atomic_read(&p->d_count) > ino_count) {
e0a7aae9	188	top_ino->last_used = jiffies;
1aff3c8b IK	189	dput(p);
	190	return 1;
	191	}
1da177e4	192	}
1ce12bad	193	dput(p);
1da177e4	194	spin_lock(&dcache_lock);
1da177e4 LT	195	}
1da177e4 LT	196	spin_unlock(&dcache_lock);
1aff3c8b IK	197
	198	/* Timeout of a tree mount is ultimately determined by its top dentry */
	199	if (!autofs4_can_expire(top, timeout, do_now))
	200	return 1;
	201
1f5f2c30	202	return 0;
1da177e4 LT	203	}
	204
	205	static struct dentry autofs4_check_leaves(struct vfsmount mnt,
	206	struct dentry *parent,
	207	unsigned long timeout,
	208	int do_now)
	209	{
1ce12bad	210	struct dentry *p;
1da177e4 LT	211
	212	DPRINTK("parent %p %.*s",
	213	parent, (int)parent->d_name.len, parent->d_name.name);
	214
	215	spin_lock(&dcache_lock);
1ce12bad	216	for (p = parent; p; p = next_dentry(p, parent)) {
1da177e4	217	/* Negative dentry - give up */
1ce12bad	218	if (!simple_positive(p))
1da177e4	219	continue;
1da177e4 LT	220
1da177e4 LT	221	DPRINTK("dentry %p %.*s",
1ce12bad	222	p, (int) p->d_name.len, p->d_name.name);
1da177e4	223
1ce12bad	224	p = dget(p);
1da177e4 LT	225	spin_unlock(&dcache_lock);
1da177e4 LT	226
1ce12bad	227	if (d_mountpoint(p)) {
e0a7aae9 IK	228	/* Can we umount this guy */
e0a7aae9 IK	229	if (autofs4_mount_busy(mnt, p))
1da177e4 LT	230	goto cont;
1da177e4 LT	231
e0a7aae9 IK	232	/* Can we expire this guy */
e0a7aae9 IK	233	if (autofs4_can_expire(p, timeout, do_now))
1ce12bad	234	return p;
1da177e4 LT	235	}
1da177e4 LT	236	cont:
1ce12bad	237	dput(p);
1da177e4	238	spin_lock(&dcache_lock);
1da177e4 LT	239	}
1da177e4 LT	240	spin_unlock(&dcache_lock);
1da177e4 LT	241	return NULL;
	242	}
	243
3a15e2ab IK	244	/* Check if we can expire a direct mount (possibly a tree) */
	245	static struct dentry autofs4_expire_direct(struct super_block sb,
	246	struct vfsmount *mnt,
	247	struct autofs_sb_info *sbi,
	248	int how)
	249	{
	250	unsigned long timeout;
	251	struct dentry *root = dget(sb->s_root);
	252	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	253
	254	if (!sbi->exp_timeout \|\| !root)
	255	return NULL;
	256
	257	now = jiffies;
	258	timeout = sbi->exp_timeout;
	259
	260	/* Lock the tree as we must expire as a whole */
	261	spin_lock(&sbi->fs_lock);
	262	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
	263	struct autofs_info *ino = autofs4_dentry_ino(root);
	264
	265	/* Set this flag early to catch sys_chdir and the like */
	266	ino->flags \|= AUTOFS_INF_EXPIRING;
	267	spin_unlock(&sbi->fs_lock);
	268	return root;
	269	}
	270	spin_unlock(&sbi->fs_lock);
	271	dput(root);
	272
	273	return NULL;
	274	}
	275
1da177e4 LT	276	/*
	277	* Find an eligible tree to time-out
	278	* A tree is eligible if :-
	279	* - it is unused by any user process
	280	* - it has been unused for exp_timeout time
	281	*/
3a15e2ab IK	282	static struct dentry autofs4_expire_indirect(struct super_block sb,
	283	struct vfsmount *mnt,
	284	struct autofs_sb_info *sbi,
	285	int how)
1da177e4 LT	286	{
	287	unsigned long timeout;
	288	struct dentry *root = sb->s_root;
	289	struct dentry *expired = NULL;
	290	struct list_head *next;
	291	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	292	int exp_leaves = how & AUTOFS_EXP_LEAVES;
	293
	294	if ( !sbi->exp_timeout \|\| !root )
	295	return NULL;
	296
	297	now = jiffies;
	298	timeout = sbi->exp_timeout;
	299
	300	spin_lock(&dcache_lock);
	301	next = root->d_subdirs.next;
	302
	303	/* On exit from the loop expire is set to a dgot dentry
	304	* to expire or it's NULL */
	305	while ( next != &root->d_subdirs ) {
5160ee6f	306	struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
1da177e4 LT	307
1da177e4 LT	308	/* Negative dentry - give up */
1f5f2c30	309	if (!simple_positive(dentry)) {
1da177e4 LT	310	next = next->next;
	311	continue;
	312	}
	313
	314	dentry = dget(dentry);
	315	spin_unlock(&dcache_lock);
	316
3a15e2ab IK	317	/*
	318	* Case 1: (i) indirect mount or top level pseudo direct mount
	319	* (autofs-4.1).
	320	* (ii) indirect mount with offset mount, check the "/"
	321	* offset (autofs-5.0+).
	322	*/
1da177e4 LT	323	if (d_mountpoint(dentry)) {
	324	DPRINTK("checking mountpoint %p %.*s",
	325	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	326
e0a7aae9 IK	327	/* Can we umount this guy */
e0a7aae9 IK	328	if (autofs4_mount_busy(mnt, dentry))
1da177e4 LT	329	goto next;
1da177e4 LT	330
e0a7aae9 IK	331	/* Can we expire this guy */
e0a7aae9 IK	332	if (autofs4_can_expire(dentry, timeout, do_now)) {
1da177e4 LT	333	expired = dentry;
	334	break;
	335	}
	336	goto next;
	337	}
	338
1f5f2c30	339	if (simple_empty(dentry))
1da177e4 LT	340	goto next;
	341
	342	/* Case 2: tree mount, expire iff entire tree is not busy */
	343	if (!exp_leaves) {
3a9720ce IK	344	/* Lock the tree as we must expire as a whole */
3a9720ce IK	345	spin_lock(&sbi->fs_lock);
1f5f2c30	346	if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
3a9720ce IK	347	struct autofs_info *inf = autofs4_dentry_ino(dentry);
	348
	349	/* Set this flag early to catch sys_chdir and the like */
	350	inf->flags \|= AUTOFS_INF_EXPIRING;
	351	spin_unlock(&sbi->fs_lock);
	352	expired = dentry;
	353	break;
1da177e4	354	}
3a9720ce	355	spin_unlock(&sbi->fs_lock);
3a15e2ab IK	356	/*
	357	* Case 3: pseudo direct mount, expire individual leaves
	358	* (autofs-4.1).
	359	*/
1da177e4 LT	360	} else {
	361	expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
	362	if (expired) {
	363	dput(dentry);
	364	break;
	365	}
	366	}
	367	next:
	368	dput(dentry);
	369	spin_lock(&dcache_lock);
	370	next = next->next;
	371	}
	372
1f5f2c30	373	if (expired) {
1da177e4 LT	374	DPRINTK("returning %p %.*s",
	375	expired, (int)expired->d_name.len, expired->d_name.name);
	376	spin_lock(&dcache_lock);
	377	list_del(&expired->d_parent->d_subdirs);
5160ee6f	378	list_add(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
1da177e4 LT	379	spin_unlock(&dcache_lock);
	380	return expired;
	381	}
	382	spin_unlock(&dcache_lock);
	383
	384	return NULL;
	385	}
	386
	387	/* Perform an expiry operation */
	388	int autofs4_expire_run(struct super_block *sb,
	389	struct vfsmount *mnt,
	390	struct autofs_sb_info *sbi,
	391	struct autofs_packet_expire __user *pkt_p)
	392	{
	393	struct autofs_packet_expire pkt;
	394	struct dentry *dentry;
	395
	396	memset(&pkt,0,sizeof pkt);
	397
	398	pkt.hdr.proto_version = sbi->version;
	399	pkt.hdr.type = autofs_ptype_expire;
	400
3a15e2ab	401	if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
1da177e4 LT	402	return -EAGAIN;
	403
	404	pkt.len = dentry->d_name.len;
	405	memcpy(pkt.name, dentry->d_name.name, pkt.len);
	406	pkt.name[pkt.len] = '\0';
	407	dput(dentry);
	408
	409	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
	410	return -EFAULT;
	411
	412	return 0;
	413	}
	414
	415	/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
	416	more to be done */
	417	int autofs4_expire_multi(struct super_block sb, struct vfsmount mnt,
	418	struct autofs_sb_info sbi, int __user arg)
	419	{
	420	struct dentry *dentry;
	421	int ret = -EAGAIN;
	422	int do_now = 0;
	423
	424	if (arg && get_user(do_now, arg))
	425	return -EFAULT;
	426
44d53eb0	427	if (sbi->type & AUTOFS_TYPE_DIRECT)
3a15e2ab IK	428	dentry = autofs4_expire_direct(sb, mnt, sbi, do_now);
	429	else
	430	dentry = autofs4_expire_indirect(sb, mnt, sbi, do_now);
	431
	432	if (dentry) {
1f5f2c30	433	struct autofs_info *ino = autofs4_dentry_ino(dentry);
1da177e4 LT	434
	435	/* This is synchronous because it makes the daemon a
	436	little easier */
1f5f2c30	437	ino->flags \|= AUTOFS_INF_EXPIRING;
1da177e4	438	ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
1f5f2c30	439	ino->flags &= ~AUTOFS_INF_EXPIRING;
1da177e4 LT	440	dput(dentry);
1da177e4 LT	441	}
1f5f2c30	442
1da177e4 LT	443	return ret;
	444	}
	445