[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 (!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 (!follow_down(&mnt, &dentry))
		goto done;

	if (is_autofs4_dentry(dentry)) {
		struct autofs_sb_info *sbi = autofs4_sbi(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(dentry)) {
			status = 0;
			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) */
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
 */
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;
}

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);
		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;
}

/* 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
	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
bc9c4068	59	if (!follow_down(&mnt, &dentry))
1da177e4 LT	60	goto done;
1da177e4 LT	61
bc9c4068 IK	62	if (is_autofs4_dentry(dentry)) {
	63	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
	64
	65	/* This is an autofs submount, we can't expire it */
a92daf6b	66	if (autofs_type_indirect(sbi->type))
bc9c4068 IK	67	goto done;
	68
	69	/*
	70	* Otherwise it's an offset mount and we need to check
	71	* if we can umount its mount, if there is one.
	72	*/
a8985f3a IK	73	if (!d_mountpoint(dentry)) {
a8985f3a IK	74	status = 0;
bc9c4068	75	goto done;
a8985f3a	76	}
bc9c4068	77	}
1da177e4	78
e0a7aae9	79	/* Update the expiry counter if fs is busy */
e3474a8e	80	if (!may_umount_tree(mnt)) {
e0a7aae9 IK	81	struct autofs_info *ino = autofs4_dentry_ino(top);
	82	ino->last_used = jiffies;
	83	goto done;
	84	}
	85
	86	status = 0;
1da177e4 LT	87	done:
1da177e4 LT	88	DPRINTK("returning = %d", status);
1da177e4	89	dput(dentry);
868eb7a8	90	mntput(mnt);
1da177e4 LT	91	return status;
	92	}
	93
1ce12bad IK	94	/*
	95	* Calculate next entry in top down tree traversal.
	96	* From next_mnt in namespace.c - elegant.
	97	*/
	98	static struct dentry next_dentry(struct dentry p, struct dentry *root)
	99	{
	100	struct list_head *next = p->d_subdirs.next;
	101
	102	if (next == &p->d_subdirs) {
	103	while (1) {
	104	if (p == root)
	105	return NULL;
	106	next = p->d_u.d_child.next;
	107	if (next != &p->d_parent->d_subdirs)
	108	break;
	109	p = p->d_parent;
	110	}
	111	}
	112	return list_entry(next, struct dentry, d_u.d_child);
	113	}
	114
3a15e2ab IK	115	/*
	116	* Check a direct mount point for busyness.
	117	* Direct mounts have similar expiry semantics to tree mounts.
	118	* The tree is not busy iff no mountpoints are busy and there are no
	119	* autofs submounts.
	120	*/
	121	static int autofs4_direct_busy(struct vfsmount *mnt,
	122	struct dentry *top,
	123	unsigned long timeout,
	124	int do_now)
	125	{
	126	DPRINTK("top %p %.*s",
	127	top, (int) top->d_name.len, top->d_name.name);
	128
3a15e2ab IK	129	/* If it's busy update the expiry counters */
	130	if (!may_umount_tree(mnt)) {
	131	struct autofs_info *ino = autofs4_dentry_ino(top);
	132	if (ino)
	133	ino->last_used = jiffies;
	134	return 1;
	135	}
	136
	137	/* Timeout of a direct mount is determined by its top dentry */
	138	if (!autofs4_can_expire(top, timeout, do_now))
	139	return 1;
	140
	141	return 0;
	142	}
	143
1da177e4 LT	144	/* Check a directory tree of mount points for busyness
1da177e4 LT	145	* The tree is not busy iff no mountpoints are busy
1da177e4	146	*/
1f5f2c30 IK	147	static int autofs4_tree_busy(struct vfsmount *mnt,
	148	struct dentry *top,
	149	unsigned long timeout,
	150	int do_now)
1da177e4	151	{
e0a7aae9	152	struct autofs_info *top_ino = autofs4_dentry_ino(top);
1ce12bad	153	struct dentry *p;
1da177e4	154
1f5f2c30	155	DPRINTK("top %p %.*s",
1da177e4 LT	156	top, (int)top->d_name.len, top->d_name.name);
	157
	158	/* Negative dentry - give up */
	159	if (!simple_positive(top))
1f5f2c30	160	return 1;
1da177e4	161
1da177e4	162	spin_lock(&dcache_lock);
1ce12bad	163	for (p = top; p; p = next_dentry(p, top)) {
1da177e4	164	/* Negative dentry - give up */
1ce12bad	165	if (!simple_positive(p))
1da177e4	166	continue;
1da177e4 LT	167
1da177e4 LT	168	DPRINTK("dentry %p %.*s",
1ce12bad	169	p, (int) p->d_name.len, p->d_name.name);
1da177e4	170
1ce12bad	171	p = dget(p);
1da177e4 LT	172	spin_unlock(&dcache_lock);
1da177e4 LT	173
1aff3c8b IK	174	/*
	175	* Is someone visiting anywhere in the subtree ?
	176	* If there's no mount we need to check the usage
	177	* count for the autofs dentry.
e0a7aae9	178	* If the fs is busy update the expiry counter.
1aff3c8b	179	*/
1ce12bad	180	if (d_mountpoint(p)) {
1ce12bad	181	if (autofs4_mount_busy(mnt, p)) {
e0a7aae9	182	top_ino->last_used = jiffies;
1ce12bad	183	dput(p);
1f5f2c30	184	return 1;
1da177e4	185	}
1aff3c8b	186	} else {
e0a7aae9	187	struct autofs_info *ino = autofs4_dentry_ino(p);
1aff3c8b IK	188	unsigned int ino_count = atomic_read(&ino->count);
1aff3c8b IK	189
f9022f66 IK	190	/*
	191	* Clean stale dentries below that have not been
	192	* invalidated after a mount fail during lookup
	193	*/
	194	d_invalidate(p);
	195
1aff3c8b IK	196	/* allow for dget above and top is already dgot */
	197	if (p == top)
	198	ino_count += 2;
	199	else
	200	ino_count++;
	201
	202	if (atomic_read(&p->d_count) > ino_count) {
e0a7aae9	203	top_ino->last_used = jiffies;
1aff3c8b IK	204	dput(p);
	205	return 1;
	206	}
1da177e4	207	}
1ce12bad	208	dput(p);
1da177e4	209	spin_lock(&dcache_lock);
1da177e4 LT	210	}
1da177e4 LT	211	spin_unlock(&dcache_lock);
1aff3c8b IK	212
	213	/* Timeout of a tree mount is ultimately determined by its top dentry */
	214	if (!autofs4_can_expire(top, timeout, do_now))
	215	return 1;
	216
1f5f2c30	217	return 0;
1da177e4 LT	218	}
	219
	220	static struct dentry autofs4_check_leaves(struct vfsmount mnt,
	221	struct dentry *parent,
	222	unsigned long timeout,
	223	int do_now)
	224	{
1ce12bad	225	struct dentry *p;
1da177e4 LT	226
	227	DPRINTK("parent %p %.*s",
	228	parent, (int)parent->d_name.len, parent->d_name.name);
	229
	230	spin_lock(&dcache_lock);
1ce12bad	231	for (p = parent; p; p = next_dentry(p, parent)) {
1da177e4	232	/* Negative dentry - give up */
1ce12bad	233	if (!simple_positive(p))
1da177e4	234	continue;
1da177e4 LT	235
1da177e4 LT	236	DPRINTK("dentry %p %.*s",
1ce12bad	237	p, (int) p->d_name.len, p->d_name.name);
1da177e4	238
1ce12bad	239	p = dget(p);
1da177e4 LT	240	spin_unlock(&dcache_lock);
1da177e4 LT	241
1ce12bad	242	if (d_mountpoint(p)) {
e0a7aae9 IK	243	/* Can we umount this guy */
e0a7aae9 IK	244	if (autofs4_mount_busy(mnt, p))
1da177e4 LT	245	goto cont;
1da177e4 LT	246
e0a7aae9 IK	247	/* Can we expire this guy */
e0a7aae9 IK	248	if (autofs4_can_expire(p, timeout, do_now))
1ce12bad	249	return p;
1da177e4 LT	250	}
1da177e4 LT	251	cont:
1ce12bad	252	dput(p);
1da177e4	253	spin_lock(&dcache_lock);
1da177e4 LT	254	}
1da177e4 LT	255	spin_unlock(&dcache_lock);
1da177e4 LT	256	return NULL;
	257	}
	258
3a15e2ab	259	/* Check if we can expire a direct mount (possibly a tree) */
8d7b48e0 IK	260	struct dentry autofs4_expire_direct(struct super_block sb,
	261	struct vfsmount *mnt,
	262	struct autofs_sb_info *sbi,
	263	int how)
3a15e2ab IK	264	{
	265	unsigned long timeout;
	266	struct dentry *root = dget(sb->s_root);
	267	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	268
c0ba7e51	269	if (!root)
3a15e2ab IK	270	return NULL;
	271
	272	now = jiffies;
	273	timeout = sbi->exp_timeout;
	274
3a15e2ab IK	275	spin_lock(&sbi->fs_lock);
	276	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
	277	struct autofs_info *ino = autofs4_dentry_ino(root);
6e60a9ab IK	278	if (d_mountpoint(root)) {
	279	ino->flags \|= AUTOFS_INF_MOUNTPOINT;
	280	root->d_mounted--;
	281	}
3a15e2ab	282	ino->flags \|= AUTOFS_INF_EXPIRING;
6e60a9ab	283	init_completion(&ino->expire_complete);
3a15e2ab IK	284	spin_unlock(&sbi->fs_lock);
	285	return root;
	286	}
	287	spin_unlock(&sbi->fs_lock);
	288	dput(root);
	289
	290	return NULL;
	291	}
	292
1da177e4 LT	293	/*
	294	* Find an eligible tree to time-out
	295	* A tree is eligible if :-
	296	* - it is unused by any user process
	297	* - it has been unused for exp_timeout time
	298	*/
8d7b48e0 IK	299	struct dentry autofs4_expire_indirect(struct super_block sb,
	300	struct vfsmount *mnt,
	301	struct autofs_sb_info *sbi,
	302	int how)
1da177e4 LT	303	{
	304	unsigned long timeout;
	305	struct dentry *root = sb->s_root;
	306	struct dentry *expired = NULL;
	307	struct list_head *next;
	308	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	309	int exp_leaves = how & AUTOFS_EXP_LEAVES;
97e7449a IK	310	struct autofs_info *ino;
97e7449a IK	311	unsigned int ino_count;
1da177e4	312
c0ba7e51	313	if (!root)
1da177e4 LT	314	return NULL;
	315
	316	now = jiffies;
	317	timeout = sbi->exp_timeout;
	318
	319	spin_lock(&dcache_lock);
	320	next = root->d_subdirs.next;
	321
	322	/* On exit from the loop expire is set to a dgot dentry
	323	* to expire or it's NULL */
	324	while ( next != &root->d_subdirs ) {
5160ee6f	325	struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
1da177e4 LT	326
1da177e4 LT	327	/* Negative dentry - give up */
1f5f2c30	328	if (!simple_positive(dentry)) {
1da177e4 LT	329	next = next->next;
	330	continue;
	331	}
	332
	333	dentry = dget(dentry);
	334	spin_unlock(&dcache_lock);
	335
97e7449a IK	336	spin_lock(&sbi->fs_lock);
	337	ino = autofs4_dentry_ino(dentry);
	338
3a15e2ab IK	339	/*
	340	* Case 1: (i) indirect mount or top level pseudo direct mount
	341	* (autofs-4.1).
	342	* (ii) indirect mount with offset mount, check the "/"
	343	* offset (autofs-5.0+).
	344	*/
1da177e4 LT	345	if (d_mountpoint(dentry)) {
	346	DPRINTK("checking mountpoint %p %.*s",
	347	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	348
97e7449a IK	349	/* Path walk currently on this dentry? */
	350	ino_count = atomic_read(&ino->count) + 2;
	351	if (atomic_read(&dentry->d_count) > ino_count)
	352	goto next;
	353
e0a7aae9 IK	354	/* Can we umount this guy */
e0a7aae9 IK	355	if (autofs4_mount_busy(mnt, dentry))
1da177e4 LT	356	goto next;
1da177e4 LT	357
e0a7aae9 IK	358	/* Can we expire this guy */
e0a7aae9 IK	359	if (autofs4_can_expire(dentry, timeout, do_now)) {
1da177e4	360	expired = dentry;
afec570c	361	goto found;
1da177e4 LT	362	}
	363	goto next;
	364	}
	365
1f5f2c30	366	if (simple_empty(dentry))
1da177e4 LT	367	goto next;
	368
	369	/* Case 2: tree mount, expire iff entire tree is not busy */
	370	if (!exp_leaves) {
97e7449a IK	371	/* Path walk currently on this dentry? */
	372	ino_count = atomic_read(&ino->count) + 1;
	373	if (atomic_read(&dentry->d_count) > ino_count)
	374	goto next;
3a9720ce	375
97e7449a	376	if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
3a9720ce	377	expired = dentry;
afec570c	378	goto found;
1da177e4	379	}
3a15e2ab IK	380	/*
	381	* Case 3: pseudo direct mount, expire individual leaves
	382	* (autofs-4.1).
	383	*/
1da177e4	384	} else {
97e7449a IK	385	/* Path walk currently on this dentry? */
	386	ino_count = atomic_read(&ino->count) + 1;
	387	if (atomic_read(&dentry->d_count) > ino_count)
	388	goto next;
	389
1da177e4 LT	390	expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
	391	if (expired) {
	392	dput(dentry);
afec570c	393	goto found;
1da177e4 LT	394	}
	395	}
	396	next:
97e7449a	397	spin_unlock(&sbi->fs_lock);
1da177e4 LT	398	dput(dentry);
	399	spin_lock(&dcache_lock);
	400	next = next->next;
	401	}
1da177e4	402	spin_unlock(&dcache_lock);
1da177e4	403	return NULL;
afec570c IK	404
	405	found:
	406	DPRINTK("returning %p %.*s",
	407	expired, (int)expired->d_name.len, expired->d_name.name);
97e7449a IK	408	ino = autofs4_dentry_ino(expired);
97e7449a IK	409	ino->flags \|= AUTOFS_INF_EXPIRING;
6e60a9ab	410	init_completion(&ino->expire_complete);
97e7449a	411	spin_unlock(&sbi->fs_lock);
afec570c IK	412	spin_lock(&dcache_lock);
	413	list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
	414	spin_unlock(&dcache_lock);
	415	return expired;
1da177e4 LT	416	}
1da177e4 LT	417
06a35985 IK	418	int autofs4_expire_wait(struct dentry *dentry)
	419	{
	420	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
	421	struct autofs_info *ino = autofs4_dentry_ino(dentry);
	422	int status;
	423
	424	/* Block on any pending expire */
	425	spin_lock(&sbi->fs_lock);
	426	if (ino->flags & AUTOFS_INF_EXPIRING) {
	427	spin_unlock(&sbi->fs_lock);
	428
	429	DPRINTK("waiting for expire %p name=%.*s",
	430	dentry, dentry->d_name.len, dentry->d_name.name);
	431
	432	status = autofs4_wait(sbi, dentry, NFY_NONE);
	433	wait_for_completion(&ino->expire_complete);
	434
	435	DPRINTK("expire done status=%d", status);
	436
	437	if (d_unhashed(dentry))
	438	return -EAGAIN;
	439
	440	return status;
	441	}
	442	spin_unlock(&sbi->fs_lock);
	443
	444	return 0;
	445	}
	446
1da177e4 LT	447	/* Perform an expiry operation */
	448	int autofs4_expire_run(struct super_block *sb,
	449	struct vfsmount *mnt,
	450	struct autofs_sb_info *sbi,
	451	struct autofs_packet_expire __user *pkt_p)
	452	{
	453	struct autofs_packet_expire pkt;
97e7449a	454	struct autofs_info *ino;
1da177e4	455	struct dentry *dentry;
97e7449a	456	int ret = 0;
1da177e4 LT	457
	458	memset(&pkt,0,sizeof pkt);
	459
	460	pkt.hdr.proto_version = sbi->version;
	461	pkt.hdr.type = autofs_ptype_expire;
	462
3a15e2ab	463	if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
1da177e4 LT	464	return -EAGAIN;
	465
	466	pkt.len = dentry->d_name.len;
	467	memcpy(pkt.name, dentry->d_name.name, pkt.len);
	468	pkt.name[pkt.len] = '\0';
	469	dput(dentry);
	470
	471	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
97e7449a	472	ret = -EFAULT;
1da177e4	473
97e7449a IK	474	spin_lock(&sbi->fs_lock);
	475	ino = autofs4_dentry_ino(dentry);
	476	ino->flags &= ~AUTOFS_INF_EXPIRING;
6e60a9ab	477	complete_all(&ino->expire_complete);
97e7449a IK	478	spin_unlock(&sbi->fs_lock);
	479
	480	return ret;
1da177e4 LT	481	}
1da177e4 LT	482
56fcef75 IK	483	int autofs4_do_expire_multi(struct super_block sb, struct vfsmount mnt,
56fcef75 IK	484	struct autofs_sb_info *sbi, int when)
1da177e4 LT	485	{
	486	struct dentry *dentry;
	487	int ret = -EAGAIN;
1da177e4	488
a92daf6b	489	if (autofs_type_trigger(sbi->type))
56fcef75	490	dentry = autofs4_expire_direct(sb, mnt, sbi, when);
3a15e2ab	491	else
56fcef75	492	dentry = autofs4_expire_indirect(sb, mnt, sbi, when);
3a15e2ab IK	493
3a15e2ab IK	494	if (dentry) {
1f5f2c30	495	struct autofs_info *ino = autofs4_dentry_ino(dentry);
1da177e4 LT	496
	497	/* This is synchronous because it makes the daemon a
	498	little easier */
1da177e4	499	ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
6e60a9ab	500
97e7449a	501	spin_lock(&sbi->fs_lock);
6e60a9ab IK	502	if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
	503	sb->s_root->d_mounted++;
	504	ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
	505	}
1f5f2c30	506	ino->flags &= ~AUTOFS_INF_EXPIRING;
6e60a9ab	507	complete_all(&ino->expire_complete);
97e7449a	508	spin_unlock(&sbi->fs_lock);
1da177e4 LT	509	dput(dentry);
1da177e4 LT	510	}
1f5f2c30	511
1da177e4 LT	512	return ret;
	513	}
	514
56fcef75 IK	515	/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
	516	more to be done */
	517	int autofs4_expire_multi(struct super_block sb, struct vfsmount mnt,
	518	struct autofs_sb_info sbi, int __user arg)
	519	{
	520	int do_now = 0;
	521
	522	if (arg && get_user(do_now, arg))
	523	return -EFAULT;
	524
	525	return autofs4_do_expire_multi(sb, mnt, sbi, do_now);
	526	}
	527