[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 2001-2003 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)
{
	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;

	/* The big question */
	if (may_umount_tree(mnt) == 0)
		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 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 *ino;
	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.
		 */
		ino = autofs4_dentry_ino(p);
		if (d_mountpoint(p)) {
			if (autofs4_mount_busy(mnt, p)) {
				dput(p);
				return 1;
			}
		} else {
			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) {
				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 expire this guy */
			if (!autofs4_can_expire(p, timeout, do_now))
				goto cont;

			/* Can we umount this guy */
			if (!autofs4_mount_busy(mnt, p))
				return p;

		}
cont:
		dput(p);
		spin_lock(&dcache_lock);
	}
	spin_unlock(&dcache_lock);
	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(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: indirect mount or top level direct mount */
		if (d_mountpoint(dentry)) {
			DPRINTK("checking mountpoint %p %.*s",
				dentry, (int)dentry->d_name.len, dentry->d_name.name);

			/* Can we expire this guy */
			if (!autofs4_can_expire(dentry, timeout, do_now))
				goto next;

			/* Can we umount this guy */
			if (!autofs4_mount_busy(mnt, dentry)) {
				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: direct mount, expire individual leaves */
		} 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(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 ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) {
		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>
	7	* Copyright 2001-2003 Ian Kent <raven@themaw.net>
	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	{
1f5f2c30	50	int status = 1;
1da177e4 LT	51
	52	DPRINTK("dentry %p %.*s",
	53	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	54
	55	mntget(mnt);
	56	dget(dentry);
	57
9b1e3afd	58	if (!autofs4_follow_mount(&mnt, &dentry))
1da177e4 LT	59	goto done;
1da177e4 LT	60
1da177e4 LT	61	/* This is an autofs submount, we can't expire it */
	62	if (is_autofs4_dentry(dentry))
	63	goto done;
	64
	65	/* The big question */
	66	if (may_umount_tree(mnt) == 0)
1f5f2c30	67	status = 0;
1da177e4 LT	68	done:
	69	DPRINTK("returning = %d", status);
	70	mntput(mnt);
	71	dput(dentry);
	72	return status;
	73	}
	74
1ce12bad IK	75	/*
	76	* Calculate next entry in top down tree traversal.
	77	* From next_mnt in namespace.c - elegant.
	78	*/
	79	static struct dentry next_dentry(struct dentry p, struct dentry *root)
	80	{
	81	struct list_head *next = p->d_subdirs.next;
	82
	83	if (next == &p->d_subdirs) {
	84	while (1) {
	85	if (p == root)
	86	return NULL;
	87	next = p->d_u.d_child.next;
	88	if (next != &p->d_parent->d_subdirs)
	89	break;
	90	p = p->d_parent;
	91	}
	92	}
	93	return list_entry(next, struct dentry, d_u.d_child);
	94	}
	95
1da177e4 LT	96	/* Check a directory tree of mount points for busyness
1da177e4 LT	97	* The tree is not busy iff no mountpoints are busy
1da177e4	98	*/
1f5f2c30 IK	99	static int autofs4_tree_busy(struct vfsmount *mnt,
	100	struct dentry *top,
	101	unsigned long timeout,
	102	int do_now)
1da177e4	103	{
1aff3c8b	104	struct autofs_info *ino;
1ce12bad	105	struct dentry *p;
1da177e4	106
1f5f2c30	107	DPRINTK("top %p %.*s",
1da177e4 LT	108	top, (int)top->d_name.len, top->d_name.name);
	109
	110	/* Negative dentry - give up */
	111	if (!simple_positive(top))
1f5f2c30	112	return 1;
1da177e4	113
1da177e4	114	spin_lock(&dcache_lock);
1ce12bad	115	for (p = top; p; p = next_dentry(p, top)) {
1da177e4	116	/* Negative dentry - give up */
1ce12bad	117	if (!simple_positive(p))
1da177e4	118	continue;
1da177e4 LT	119
1da177e4 LT	120	DPRINTK("dentry %p %.*s",
1ce12bad	121	p, (int) p->d_name.len, p->d_name.name);
1da177e4	122
1ce12bad	123	p = dget(p);
1da177e4 LT	124	spin_unlock(&dcache_lock);
1da177e4 LT	125
1aff3c8b IK	126	/*
	127	* Is someone visiting anywhere in the subtree ?
	128	* If there's no mount we need to check the usage
	129	* count for the autofs dentry.
	130	*/
	131	ino = autofs4_dentry_ino(p);
1ce12bad	132	if (d_mountpoint(p)) {
1ce12bad IK	133	if (autofs4_mount_busy(mnt, p)) {
1ce12bad IK	134	dput(p);
1f5f2c30	135	return 1;
1da177e4	136	}
1aff3c8b IK	137	} else {
	138	unsigned int ino_count = atomic_read(&ino->count);
	139
	140	/* allow for dget above and top is already dgot */
	141	if (p == top)
	142	ino_count += 2;
	143	else
	144	ino_count++;
	145
	146	if (atomic_read(&p->d_count) > ino_count) {
	147	dput(p);
	148	return 1;
	149	}
1da177e4	150	}
1ce12bad	151	dput(p);
1da177e4	152	spin_lock(&dcache_lock);
1da177e4 LT	153	}
1da177e4 LT	154	spin_unlock(&dcache_lock);
1aff3c8b IK	155
	156	/* Timeout of a tree mount is ultimately determined by its top dentry */
	157	if (!autofs4_can_expire(top, timeout, do_now))
	158	return 1;
	159
1f5f2c30	160	return 0;
1da177e4 LT	161	}
	162
	163	static struct dentry autofs4_check_leaves(struct vfsmount mnt,
	164	struct dentry *parent,
	165	unsigned long timeout,
	166	int do_now)
	167	{
1ce12bad	168	struct dentry *p;
1da177e4 LT	169
	170	DPRINTK("parent %p %.*s",
	171	parent, (int)parent->d_name.len, parent->d_name.name);
	172
	173	spin_lock(&dcache_lock);
1ce12bad	174	for (p = parent; p; p = next_dentry(p, parent)) {
1da177e4	175	/* Negative dentry - give up */
1ce12bad	176	if (!simple_positive(p))
1da177e4	177	continue;
1da177e4 LT	178
1da177e4 LT	179	DPRINTK("dentry %p %.*s",
1ce12bad	180	p, (int) p->d_name.len, p->d_name.name);
1da177e4	181
1ce12bad	182	p = dget(p);
1da177e4 LT	183	spin_unlock(&dcache_lock);
1da177e4 LT	184
1ce12bad	185	if (d_mountpoint(p)) {
1da177e4	186	/* Can we expire this guy */
1ce12bad	187	if (!autofs4_can_expire(p, timeout, do_now))
1da177e4 LT	188	goto cont;
	189
	190	/* Can we umount this guy */
1ce12bad IK	191	if (!autofs4_mount_busy(mnt, p))
1ce12bad IK	192	return p;
1da177e4 LT	193
	194	}
	195	cont:
1ce12bad	196	dput(p);
1da177e4	197	spin_lock(&dcache_lock);
1da177e4 LT	198	}
1da177e4 LT	199	spin_unlock(&dcache_lock);
1da177e4 LT	200	return NULL;
	201	}
	202
	203	/*
	204	* Find an eligible tree to time-out
	205	* A tree is eligible if :-
	206	* - it is unused by any user process
	207	* - it has been unused for exp_timeout time
	208	*/
	209	static struct dentry autofs4_expire(struct super_block sb,
	210	struct vfsmount *mnt,
	211	struct autofs_sb_info *sbi,
	212	int how)
	213	{
	214	unsigned long timeout;
	215	struct dentry *root = sb->s_root;
	216	struct dentry *expired = NULL;
	217	struct list_head *next;
	218	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	219	int exp_leaves = how & AUTOFS_EXP_LEAVES;
	220
	221	if ( !sbi->exp_timeout \|\| !root )
	222	return NULL;
	223
	224	now = jiffies;
	225	timeout = sbi->exp_timeout;
	226
	227	spin_lock(&dcache_lock);
	228	next = root->d_subdirs.next;
	229
	230	/* On exit from the loop expire is set to a dgot dentry
	231	* to expire or it's NULL */
	232	while ( next != &root->d_subdirs ) {
5160ee6f	233	struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
1da177e4 LT	234
1da177e4 LT	235	/* Negative dentry - give up */
1f5f2c30	236	if (!simple_positive(dentry)) {
1da177e4 LT	237	next = next->next;
	238	continue;
	239	}
	240
	241	dentry = dget(dentry);
	242	spin_unlock(&dcache_lock);
	243
	244	/* Case 1: indirect mount or top level direct mount */
	245	if (d_mountpoint(dentry)) {
	246	DPRINTK("checking mountpoint %p %.*s",
	247	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	248
	249	/* Can we expire this guy */
	250	if (!autofs4_can_expire(dentry, timeout, do_now))
	251	goto next;
	252
	253	/* Can we umount this guy */
1f5f2c30	254	if (!autofs4_mount_busy(mnt, dentry)) {
1da177e4 LT	255	expired = dentry;
	256	break;
	257	}
	258	goto next;
	259	}
	260
1f5f2c30	261	if (simple_empty(dentry))
1da177e4 LT	262	goto next;
	263
	264	/* Case 2: tree mount, expire iff entire tree is not busy */
	265	if (!exp_leaves) {
3a9720ce IK	266	/* Lock the tree as we must expire as a whole */
3a9720ce IK	267	spin_lock(&sbi->fs_lock);
1f5f2c30	268	if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
3a9720ce IK	269	struct autofs_info *inf = autofs4_dentry_ino(dentry);
	270
	271	/* Set this flag early to catch sys_chdir and the like */
	272	inf->flags \|= AUTOFS_INF_EXPIRING;
	273	spin_unlock(&sbi->fs_lock);
	274	expired = dentry;
	275	break;
1da177e4	276	}
3a9720ce	277	spin_unlock(&sbi->fs_lock);
1da177e4 LT	278	/* Case 3: direct mount, expire individual leaves */
	279	} else {
	280	expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
	281	if (expired) {
	282	dput(dentry);
	283	break;
	284	}
	285	}
	286	next:
	287	dput(dentry);
	288	spin_lock(&dcache_lock);
	289	next = next->next;
	290	}
	291
1f5f2c30	292	if (expired) {
1da177e4 LT	293	DPRINTK("returning %p %.*s",
	294	expired, (int)expired->d_name.len, expired->d_name.name);
	295	spin_lock(&dcache_lock);
	296	list_del(&expired->d_parent->d_subdirs);
5160ee6f	297	list_add(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
1da177e4 LT	298	spin_unlock(&dcache_lock);
	299	return expired;
	300	}
	301	spin_unlock(&dcache_lock);
	302
	303	return NULL;
	304	}
	305
	306	/* Perform an expiry operation */
	307	int autofs4_expire_run(struct super_block *sb,
	308	struct vfsmount *mnt,
	309	struct autofs_sb_info *sbi,
	310	struct autofs_packet_expire __user *pkt_p)
	311	{
	312	struct autofs_packet_expire pkt;
	313	struct dentry *dentry;
	314
	315	memset(&pkt,0,sizeof pkt);
	316
	317	pkt.hdr.proto_version = sbi->version;
	318	pkt.hdr.type = autofs_ptype_expire;
	319
	320	if ((dentry = autofs4_expire(sb, mnt, sbi, 0)) == NULL)
	321	return -EAGAIN;
	322
	323	pkt.len = dentry->d_name.len;
	324	memcpy(pkt.name, dentry->d_name.name, pkt.len);
	325	pkt.name[pkt.len] = '\0';
	326	dput(dentry);
	327
	328	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
	329	return -EFAULT;
	330
	331	return 0;
	332	}
	333
	334	/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
	335	more to be done */
	336	int autofs4_expire_multi(struct super_block sb, struct vfsmount mnt,
	337	struct autofs_sb_info sbi, int __user arg)
	338	{
	339	struct dentry *dentry;
	340	int ret = -EAGAIN;
	341	int do_now = 0;
	342
	343	if (arg && get_user(do_now, arg))
	344	return -EFAULT;
	345
	346	if ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) {
1f5f2c30	347	struct autofs_info *ino = autofs4_dentry_ino(dentry);
1da177e4 LT	348
	349	/* This is synchronous because it makes the daemon a
	350	little easier */
1f5f2c30	351	ino->flags \|= AUTOFS_INF_EXPIRING;
1da177e4	352	ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
1f5f2c30	353	ino->flags &= ~AUTOFS_INF_EXPIRING;
1da177e4 LT	354	dput(dentry);
1da177e4 LT	355	}
1f5f2c30	356
1da177e4 LT	357	return ret;
	358	}
	359