368 lines
8.6 KiB
C
368 lines
8.6 KiB
C
/* -*- c -*- --------------------------------------------------------------- *
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*
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* linux/fs/autofs/expire.c
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*
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* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
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* Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
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* Copyright 2001-2003 Ian Kent <raven@themaw.net>
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*
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* This file is part of the Linux kernel and is made available under
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* the terms of the GNU General Public License, version 2, or at your
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* option, any later version, incorporated herein by reference.
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*
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* ------------------------------------------------------------------------- */
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#include "autofs_i.h"
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static unsigned long now;
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/* Check if a dentry can be expired return 1 if it can else return 0 */
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static inline int autofs4_can_expire(struct dentry *dentry,
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unsigned long timeout, int do_now)
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{
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struct autofs_info *ino = autofs4_dentry_ino(dentry);
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/* dentry in the process of being deleted */
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if (ino == NULL)
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return 0;
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/* No point expiring a pending mount */
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if (dentry->d_flags & DCACHE_AUTOFS_PENDING)
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return 0;
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if (!do_now) {
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/* Too young to die */
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if (time_after(ino->last_used + timeout, now))
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return 0;
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/* update last_used here :-
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- obviously makes sense if it is in use now
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- less obviously, prevents rapid-fire expire
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attempts if expire fails the first time */
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ino->last_used = now;
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}
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return 1;
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}
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/* Check a mount point for busyness return 1 if not busy, otherwise */
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static int autofs4_check_mount(struct vfsmount *mnt, struct dentry *dentry)
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{
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int status = 0;
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DPRINTK("dentry %p %.*s",
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dentry, (int)dentry->d_name.len, dentry->d_name.name);
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mntget(mnt);
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dget(dentry);
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if (!autofs4_follow_mount(&mnt, &dentry))
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goto done;
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/* This is an autofs submount, we can't expire it */
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if (is_autofs4_dentry(dentry))
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goto done;
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/* The big question */
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if (may_umount_tree(mnt) == 0)
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status = 1;
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done:
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DPRINTK("returning = %d", status);
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mntput(mnt);
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dput(dentry);
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return status;
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}
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/* Check a directory tree of mount points for busyness
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* The tree is not busy iff no mountpoints are busy
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* Return 1 if the tree is busy or 0 otherwise
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*/
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static int autofs4_check_tree(struct vfsmount *mnt,
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struct dentry *top,
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unsigned long timeout,
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int do_now)
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{
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struct dentry *this_parent = top;
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struct list_head *next;
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DPRINTK("parent %p %.*s",
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top, (int)top->d_name.len, top->d_name.name);
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/* Negative dentry - give up */
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if (!simple_positive(top))
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return 0;
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/* Timeout of a tree mount is determined by its top dentry */
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if (!autofs4_can_expire(top, timeout, do_now))
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return 0;
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/* Is someone visiting anywhere in the tree ? */
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if (may_umount_tree(mnt))
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return 0;
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spin_lock(&dcache_lock);
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repeat:
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next = this_parent->d_subdirs.next;
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resume:
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while (next != &this_parent->d_subdirs) {
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struct dentry *dentry = list_entry(next, struct dentry, d_child);
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/* Negative dentry - give up */
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if (!simple_positive(dentry)) {
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next = next->next;
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continue;
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}
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DPRINTK("dentry %p %.*s",
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dentry, (int)dentry->d_name.len, dentry->d_name.name);
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if (!simple_empty_nolock(dentry)) {
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this_parent = dentry;
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goto repeat;
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}
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dentry = dget(dentry);
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spin_unlock(&dcache_lock);
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if (d_mountpoint(dentry)) {
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/* First busy => tree busy */
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if (!autofs4_check_mount(mnt, dentry)) {
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dput(dentry);
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return 0;
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}
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}
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dput(dentry);
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spin_lock(&dcache_lock);
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next = next->next;
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}
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if (this_parent != top) {
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next = this_parent->d_child.next;
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this_parent = this_parent->d_parent;
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goto resume;
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}
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spin_unlock(&dcache_lock);
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return 1;
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}
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static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
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struct dentry *parent,
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unsigned long timeout,
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int do_now)
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{
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struct dentry *this_parent = parent;
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struct list_head *next;
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DPRINTK("parent %p %.*s",
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parent, (int)parent->d_name.len, parent->d_name.name);
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spin_lock(&dcache_lock);
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repeat:
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next = this_parent->d_subdirs.next;
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resume:
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while (next != &this_parent->d_subdirs) {
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struct dentry *dentry = list_entry(next, struct dentry, d_child);
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/* Negative dentry - give up */
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if (!simple_positive(dentry)) {
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next = next->next;
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continue;
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}
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DPRINTK("dentry %p %.*s",
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dentry, (int)dentry->d_name.len, dentry->d_name.name);
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if (!list_empty(&dentry->d_subdirs)) {
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this_parent = dentry;
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goto repeat;
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}
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dentry = dget(dentry);
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spin_unlock(&dcache_lock);
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if (d_mountpoint(dentry)) {
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/* Can we expire this guy */
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if (!autofs4_can_expire(dentry, timeout, do_now))
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goto cont;
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/* Can we umount this guy */
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if (autofs4_check_mount(mnt, dentry))
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return dentry;
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}
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cont:
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dput(dentry);
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spin_lock(&dcache_lock);
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next = next->next;
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}
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if (this_parent != parent) {
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next = this_parent->d_child.next;
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this_parent = this_parent->d_parent;
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goto resume;
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}
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spin_unlock(&dcache_lock);
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return NULL;
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}
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/*
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* Find an eligible tree to time-out
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* A tree is eligible if :-
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* - it is unused by any user process
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* - it has been unused for exp_timeout time
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*/
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static struct dentry *autofs4_expire(struct super_block *sb,
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struct vfsmount *mnt,
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struct autofs_sb_info *sbi,
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int how)
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{
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unsigned long timeout;
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struct dentry *root = sb->s_root;
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struct dentry *expired = NULL;
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struct list_head *next;
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int do_now = how & AUTOFS_EXP_IMMEDIATE;
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int exp_leaves = how & AUTOFS_EXP_LEAVES;
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if ( !sbi->exp_timeout || !root )
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return NULL;
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now = jiffies;
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timeout = sbi->exp_timeout;
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spin_lock(&dcache_lock);
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next = root->d_subdirs.next;
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/* On exit from the loop expire is set to a dgot dentry
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* to expire or it's NULL */
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while ( next != &root->d_subdirs ) {
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struct dentry *dentry = list_entry(next, struct dentry, d_child);
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/* Negative dentry - give up */
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if ( !simple_positive(dentry) ) {
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next = next->next;
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continue;
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}
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dentry = dget(dentry);
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spin_unlock(&dcache_lock);
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/* Case 1: indirect mount or top level direct mount */
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if (d_mountpoint(dentry)) {
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DPRINTK("checking mountpoint %p %.*s",
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dentry, (int)dentry->d_name.len, dentry->d_name.name);
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/* Can we expire this guy */
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if (!autofs4_can_expire(dentry, timeout, do_now))
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goto next;
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/* Can we umount this guy */
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if (autofs4_check_mount(mnt, dentry)) {
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expired = dentry;
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break;
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}
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goto next;
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}
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if ( simple_empty(dentry) )
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goto next;
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/* Case 2: tree mount, expire iff entire tree is not busy */
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if (!exp_leaves) {
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/* Lock the tree as we must expire as a whole */
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spin_lock(&sbi->fs_lock);
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if (autofs4_check_tree(mnt, dentry, timeout, do_now)) {
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struct autofs_info *inf = autofs4_dentry_ino(dentry);
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/* Set this flag early to catch sys_chdir and the like */
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inf->flags |= AUTOFS_INF_EXPIRING;
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spin_unlock(&sbi->fs_lock);
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expired = dentry;
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break;
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}
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spin_unlock(&sbi->fs_lock);
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/* Case 3: direct mount, expire individual leaves */
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} else {
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expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
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if (expired) {
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dput(dentry);
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break;
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}
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}
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next:
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dput(dentry);
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spin_lock(&dcache_lock);
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next = next->next;
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}
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if ( expired ) {
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DPRINTK("returning %p %.*s",
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expired, (int)expired->d_name.len, expired->d_name.name);
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spin_lock(&dcache_lock);
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list_del(&expired->d_parent->d_subdirs);
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list_add(&expired->d_parent->d_subdirs, &expired->d_child);
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spin_unlock(&dcache_lock);
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return expired;
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}
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spin_unlock(&dcache_lock);
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return NULL;
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}
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/* Perform an expiry operation */
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int autofs4_expire_run(struct super_block *sb,
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struct vfsmount *mnt,
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struct autofs_sb_info *sbi,
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struct autofs_packet_expire __user *pkt_p)
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{
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struct autofs_packet_expire pkt;
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struct dentry *dentry;
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memset(&pkt,0,sizeof pkt);
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pkt.hdr.proto_version = sbi->version;
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pkt.hdr.type = autofs_ptype_expire;
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if ((dentry = autofs4_expire(sb, mnt, sbi, 0)) == NULL)
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return -EAGAIN;
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pkt.len = dentry->d_name.len;
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memcpy(pkt.name, dentry->d_name.name, pkt.len);
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pkt.name[pkt.len] = '\0';
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dput(dentry);
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if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
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return -EFAULT;
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return 0;
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}
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/* Call repeatedly until it returns -EAGAIN, meaning there's nothing
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more to be done */
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int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
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struct autofs_sb_info *sbi, int __user *arg)
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{
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struct dentry *dentry;
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int ret = -EAGAIN;
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int do_now = 0;
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if (arg && get_user(do_now, arg))
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return -EFAULT;
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if ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) {
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struct autofs_info *de_info = autofs4_dentry_ino(dentry);
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/* This is synchronous because it makes the daemon a
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little easier */
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de_info->flags |= AUTOFS_INF_EXPIRING;
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ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
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de_info->flags &= ~AUTOFS_INF_EXPIRING;
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dput(dentry);
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}
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return ret;
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}
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