/* -*- 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 (!follow_down(&mnt, &dentry))
goto done;
while (d_mountpoint(dentry) && follow_down(&mnt, &dentry))
;
/* 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;
}
