[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 return 1 if it can else return 0 */
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 return 1 if not busy, otherwise */
static int autofs4_check_mount(struct vfsmount *mnt, struct dentry *dentry)
{
	int status = 0;

	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 = 1;
done:
	DPRINTK("returning = %d", status);
	mntput(mnt);
	dput(dentry);
	return status;
}

/* Check a directory tree of mount points for busyness
 * The tree is not busy iff no mountpoints are busy
 * Return 1 if the tree is busy or 0 otherwise
 */
static int autofs4_check_tree(struct vfsmount *mnt,
	       		      struct dentry *top,
			      unsigned long timeout,
			      int do_now)
{
	struct dentry *this_parent = top;
	struct list_head *next;

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

	/* Negative dentry - give up */
	if (!simple_positive(top))
		return 0;

	/* Timeout of a tree mount is determined by its top dentry */
	if (!autofs4_can_expire(top, timeout, do_now))
		return 0;

	/* Is someone visiting anywhere in the tree ? */
	if (may_umount_tree(mnt))
		return 0;

	spin_lock(&dcache_lock);
repeat:
	next = this_parent->d_subdirs.next;
resume:
	while (next != &this_parent->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;
		}

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

		if (!simple_empty_nolock(dentry)) {
			this_parent = dentry;
			goto repeat;
		}

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

		if (d_mountpoint(dentry)) {
			/* First busy => tree busy */
			if (!autofs4_check_mount(mnt, dentry)) {
				dput(dentry);
				return 0;
			}
		}

		dput(dentry);
		spin_lock(&dcache_lock);
		next = next->next;
	}

	if (this_parent != top) {
		next = this_parent->d_u.d_child.next;
		this_parent = this_parent->d_parent;
		goto resume;
	}
	spin_unlock(&dcache_lock);

	return 1;
}

static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
					   struct dentry *parent,
					   unsigned long timeout,
					   int do_now)
{
	struct dentry *this_parent = parent;
	struct list_head *next;

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

	spin_lock(&dcache_lock);
repeat:
	next = this_parent->d_subdirs.next;
resume:
	while (next != &this_parent->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;
		}

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

		if (!list_empty(&dentry->d_subdirs)) {
			this_parent = dentry;
			goto repeat;
		}

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

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

			/* Can we umount this guy */
			if (autofs4_check_mount(mnt, dentry))
				return dentry;

		}
cont:
		dput(dentry);
		spin_lock(&dcache_lock);
		next = next->next;
	}

	if (this_parent != parent) {
		next = this_parent->d_u.d_child.next;
		this_parent = this_parent->d_parent;
		goto resume;
	}
	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_check_mount(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_check_tree(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 *de_info = autofs4_dentry_ino(dentry);

		/* This is synchronous because it makes the daemon a
                   little easier */
		de_info->flags |= AUTOFS_INF_EXPIRING;
		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
		de_info->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
	19	/* Check if a dentry can be expired return 1 if it can else return 0 */
	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	}
	44
	45	return 1;
	46	}
	47
	48	/* Check a mount point for busyness return 1 if not busy, otherwise */
	49	static int autofs4_check_mount(struct vfsmount mnt, struct dentry dentry)
	50	{
	51	int status = 0;
	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
	66	/* The big question */
	67	if (may_umount_tree(mnt) == 0)
	68	status = 1;
	69	done:
	70	DPRINTK("returning = %d", status);
	71	mntput(mnt);
	72	dput(dentry);
	73	return status;
	74	}
	75
	76	/* Check a directory tree of mount points for busyness
	77	* The tree is not busy iff no mountpoints are busy
	78	* Return 1 if the tree is busy or 0 otherwise
	79	*/
	80	static int autofs4_check_tree(struct vfsmount *mnt,
	81	struct dentry *top,
	82	unsigned long timeout,
	83	int do_now)
	84	{
	85	struct dentry *this_parent = top;
	86	struct list_head *next;
	87
	88	DPRINTK("parent %p %.*s",
	89	top, (int)top->d_name.len, top->d_name.name);
	90
	91	/* Negative dentry - give up */
	92	if (!simple_positive(top))
	93	return 0;
	94
	95	/* Timeout of a tree mount is determined by its top dentry */
	96	if (!autofs4_can_expire(top, timeout, do_now))
	97	return 0;
	98
3a9720ce IK	99	/* Is someone visiting anywhere in the tree ? */
	100	if (may_umount_tree(mnt))
	101	return 0;
	102
1da177e4 LT	103	spin_lock(&dcache_lock);
	104	repeat:
	105	next = this_parent->d_subdirs.next;
	106	resume:
	107	while (next != &this_parent->d_subdirs) {
5160ee6f	108	struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
1da177e4 LT	109
	110	/* Negative dentry - give up */
	111	if (!simple_positive(dentry)) {
	112	next = next->next;
	113	continue;
	114	}
	115
	116	DPRINTK("dentry %p %.*s",
	117	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	118
	119	if (!simple_empty_nolock(dentry)) {
	120	this_parent = dentry;
	121	goto repeat;
	122	}
	123
	124	dentry = dget(dentry);
	125	spin_unlock(&dcache_lock);
	126
	127	if (d_mountpoint(dentry)) {
	128	/* First busy => tree busy */
	129	if (!autofs4_check_mount(mnt, dentry)) {
	130	dput(dentry);
	131	return 0;
	132	}
	133	}
	134
	135	dput(dentry);
	136	spin_lock(&dcache_lock);
	137	next = next->next;
	138	}
	139
	140	if (this_parent != top) {
5160ee6f	141	next = this_parent->d_u.d_child.next;
1da177e4 LT	142	this_parent = this_parent->d_parent;
	143	goto resume;
	144	}
	145	spin_unlock(&dcache_lock);
	146
	147	return 1;
	148	}
	149
	150	static struct dentry autofs4_check_leaves(struct vfsmount mnt,
	151	struct dentry *parent,
	152	unsigned long timeout,
	153	int do_now)
	154	{
	155	struct dentry *this_parent = parent;
	156	struct list_head *next;
	157
	158	DPRINTK("parent %p %.*s",
	159	parent, (int)parent->d_name.len, parent->d_name.name);
	160
	161	spin_lock(&dcache_lock);
	162	repeat:
	163	next = this_parent->d_subdirs.next;
	164	resume:
	165	while (next != &this_parent->d_subdirs) {
5160ee6f	166	struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
1da177e4 LT	167
	168	/* Negative dentry - give up */
	169	if (!simple_positive(dentry)) {
	170	next = next->next;
	171	continue;
	172	}
	173
	174	DPRINTK("dentry %p %.*s",
	175	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	176
	177	if (!list_empty(&dentry->d_subdirs)) {
	178	this_parent = dentry;
	179	goto repeat;
	180	}
	181
	182	dentry = dget(dentry);
	183	spin_unlock(&dcache_lock);
	184
	185	if (d_mountpoint(dentry)) {
	186	/* Can we expire this guy */
	187	if (!autofs4_can_expire(dentry, timeout, do_now))
	188	goto cont;
	189
	190	/* Can we umount this guy */
	191	if (autofs4_check_mount(mnt, dentry))
	192	return dentry;
	193
	194	}
	195	cont:
	196	dput(dentry);
	197	spin_lock(&dcache_lock);
	198	next = next->next;
	199	}
	200
	201	if (this_parent != parent) {
5160ee6f	202	next = this_parent->d_u.d_child.next;
1da177e4 LT	203	this_parent = this_parent->d_parent;
	204	goto resume;
	205	}
	206	spin_unlock(&dcache_lock);
	207
	208	return NULL;
	209	}
	210
	211	/*
	212	* Find an eligible tree to time-out
	213	* A tree is eligible if :-
	214	* - it is unused by any user process
	215	* - it has been unused for exp_timeout time
	216	*/
	217	static struct dentry autofs4_expire(struct super_block sb,
	218	struct vfsmount *mnt,
	219	struct autofs_sb_info *sbi,
	220	int how)
	221	{
	222	unsigned long timeout;
	223	struct dentry *root = sb->s_root;
	224	struct dentry *expired = NULL;
	225	struct list_head *next;
	226	int do_now = how & AUTOFS_EXP_IMMEDIATE;
	227	int exp_leaves = how & AUTOFS_EXP_LEAVES;
	228
	229	if ( !sbi->exp_timeout \|\| !root )
	230	return NULL;
	231
	232	now = jiffies;
	233	timeout = sbi->exp_timeout;
	234
	235	spin_lock(&dcache_lock);
	236	next = root->d_subdirs.next;
	237
	238	/* On exit from the loop expire is set to a dgot dentry
	239	* to expire or it's NULL */
	240	while ( next != &root->d_subdirs ) {
5160ee6f	241	struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
1da177e4 LT	242
	243	/* Negative dentry - give up */
	244	if ( !simple_positive(dentry) ) {
	245	next = next->next;
	246	continue;
	247	}
	248
	249	dentry = dget(dentry);
	250	spin_unlock(&dcache_lock);
	251
	252	/* Case 1: indirect mount or top level direct mount */
	253	if (d_mountpoint(dentry)) {
	254	DPRINTK("checking mountpoint %p %.*s",
	255	dentry, (int)dentry->d_name.len, dentry->d_name.name);
	256
	257	/* Can we expire this guy */
	258	if (!autofs4_can_expire(dentry, timeout, do_now))
	259	goto next;
	260
	261	/* Can we umount this guy */
	262	if (autofs4_check_mount(mnt, dentry)) {
	263	expired = dentry;
	264	break;
	265	}
	266	goto next;
	267	}
	268
	269	if ( simple_empty(dentry) )
	270	goto next;
	271
	272	/* Case 2: tree mount, expire iff entire tree is not busy */
	273	if (!exp_leaves) {
3a9720ce IK	274	/* Lock the tree as we must expire as a whole */
3a9720ce IK	275	spin_lock(&sbi->fs_lock);
1da177e4	276	if (autofs4_check_tree(mnt, dentry, timeout, do_now)) {
3a9720ce IK	277	struct autofs_info *inf = autofs4_dentry_ino(dentry);
	278
	279	/* Set this flag early to catch sys_chdir and the like */
	280	inf->flags \|= AUTOFS_INF_EXPIRING;
	281	spin_unlock(&sbi->fs_lock);
	282	expired = dentry;
	283	break;
1da177e4	284	}
3a9720ce	285	spin_unlock(&sbi->fs_lock);
1da177e4 LT	286	/* Case 3: direct mount, expire individual leaves */
	287	} else {
	288	expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
	289	if (expired) {
	290	dput(dentry);
	291	break;
	292	}
	293	}
	294	next:
	295	dput(dentry);
	296	spin_lock(&dcache_lock);
	297	next = next->next;
	298	}
	299
	300	if ( expired ) {
	301	DPRINTK("returning %p %.*s",
	302	expired, (int)expired->d_name.len, expired->d_name.name);
	303	spin_lock(&dcache_lock);
	304	list_del(&expired->d_parent->d_subdirs);
5160ee6f	305	list_add(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
1da177e4 LT	306	spin_unlock(&dcache_lock);
	307	return expired;
	308	}
	309	spin_unlock(&dcache_lock);
	310
	311	return NULL;
	312	}
	313
	314	/* Perform an expiry operation */
	315	int autofs4_expire_run(struct super_block *sb,
	316	struct vfsmount *mnt,
	317	struct autofs_sb_info *sbi,
	318	struct autofs_packet_expire __user *pkt_p)
	319	{
	320	struct autofs_packet_expire pkt;
	321	struct dentry *dentry;
	322
	323	memset(&pkt,0,sizeof pkt);
	324
	325	pkt.hdr.proto_version = sbi->version;
	326	pkt.hdr.type = autofs_ptype_expire;
	327
	328	if ((dentry = autofs4_expire(sb, mnt, sbi, 0)) == NULL)
	329	return -EAGAIN;
	330
	331	pkt.len = dentry->d_name.len;
	332	memcpy(pkt.name, dentry->d_name.name, pkt.len);
	333	pkt.name[pkt.len] = '\0';
	334	dput(dentry);
	335
	336	if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
	337	return -EFAULT;
	338
	339	return 0;
	340	}
	341
	342	/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
	343	more to be done */
	344	int autofs4_expire_multi(struct super_block sb, struct vfsmount mnt,
	345	struct autofs_sb_info sbi, int __user arg)
	346	{
	347	struct dentry *dentry;
	348	int ret = -EAGAIN;
	349	int do_now = 0;
	350
	351	if (arg && get_user(do_now, arg))
	352	return -EFAULT;
	353
	354	if ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) {
	355	struct autofs_info *de_info = autofs4_dentry_ino(dentry);
	356
	357	/* This is synchronous because it makes the daemon a
	358	little easier */
	359	de_info->flags \|= AUTOFS_INF_EXPIRING;
	360	ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
	361	de_info->flags &= ~AUTOFS_INF_EXPIRING;
	362	dput(dentry);
	363	}
	364
	365	return ret;
	366	}
	367