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/* -*- c -*- --------------------------------------------------------------- *
*
* linux/fs/autofs/expire.c
*
* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
* Copyright 1999 Jeremy Fitzhardinge <jeremy@goop.org>
*
* 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"
/*
* Determine if a subtree of the namespace is busy.
*/
static int is_tree_busy(struct vfsmount *mnt)
{
struct vfsmount *this_parent = mnt;
struct list_head *next;
int count;
spin_lock(&dcache_lock);
count = atomic_read(&mnt->mnt_count);
repeat:
next = this_parent->mnt_mounts.next;
resume:
while (next != &this_parent->mnt_mounts) {
struct list_head *tmp = next;
struct vfsmount *p = list_entry(tmp, struct vfsmount,
mnt_child);
next = tmp->next;
/* Decrement count for unused children */
count += atomic_read(&p->mnt_count) - 1;
if (!list_empty(&p->mnt_mounts)) {
this_parent = p;
goto repeat;
}
/* root is busy if any leaf is busy */
if (atomic_read(&p->mnt_count) > 1) {
spin_unlock(&dcache_lock);
return 1;
}
}
/*
* All done at this level ... ascend and resume the search.
*/
if (this_parent != mnt) {
next = this_parent->mnt_child.next;
this_parent = this_parent->mnt_parent;
goto resume;
}
spin_unlock(&dcache_lock);
DPRINTK(("is_tree_busy: count=%d\n", count));
return count != 0; /* remaining users? */
}
/*
* 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 do_now)
{
unsigned long now = jiffies; /* snapshot of now */
unsigned long timeout;
struct dentry *root = sb->s_root;
struct list_head *tmp;
struct dentry *d;
struct vfsmount *p;
if (!sbi->exp_timeout || !root)
return NULL;
timeout = sbi->exp_timeout;
spin_lock(&dcache_lock);
for(tmp = root->d_subdirs.next;
tmp != &root->d_subdirs;
tmp = tmp->next) {
struct autofs_info *ino;
struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
if (dentry->d_inode == NULL)
continue;
ino = autofs4_dentry_ino(dentry);
if (ino == NULL) {
/* dentry in the process of being deleted */
continue;
}
/* No point expiring a pending mount */
if (dentry->d_flags & DCACHE_AUTOFS_PENDING)
continue;
if (!do_now) {
/* Too young to die */
if (time_after(ino->last_used+timeout, now))
continue;
/* 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;
}
p = mntget(mnt);
d = dget(dentry);
spin_unlock(&dcache_lock);
while(d_mountpoint(d) && follow_down(&p, &d))
;
if (!is_tree_busy(p)) {
dput(d);
mntput(p);
DPRINTK(("autofs_expire: returning %p %.*s\n",
dentry, dentry->d_name.len, dentry->d_name.name));
/* Start from here next time */
spin_lock(&dcache_lock);
list_del(&root->d_subdirs);
list_add(&root->d_subdirs, &dentry->d_child);
spin_unlock(&dcache_lock);
return dentry;
}
dput(d);
mntput(p);
spin_lock(&dcache_lock);
}
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 *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';
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 *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->d_name, NFY_EXPIRE);
de_info->flags &= ~AUTOFS_INF_EXPIRING;
}
return ret;
}
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