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/* -*- 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 (sbi->type == AUTOFS_TYPE_INDIRECT)
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))
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;
ti
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