fs/autofs4/expire.c - linux/kernel/git/davem/net - Git at Google

 /* -*- 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_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_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_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_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_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_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;
 }
	/* -- 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_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_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_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_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_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_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;
	}