531 lines
13 KiB
C
531 lines
13 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 2001-2006 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 */
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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 (ino->flags & AUTOFS_INF_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 (!timeout || 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 */
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static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
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{
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struct dentry *top = dentry;
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struct path path = {.mnt = mnt, .dentry = dentry};
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int status = 1;
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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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path_get(&path);
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if (!follow_down(&path))
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goto done;
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if (is_autofs4_dentry(path.dentry)) {
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struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb);
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/* This is an autofs submount, we can't expire it */
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if (autofs_type_indirect(sbi->type))
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goto done;
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/*
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* Otherwise it's an offset mount and we need to check
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* if we can umount its mount, if there is one.
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*/
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if (!d_mountpoint(path.dentry)) {
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status = 0;
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goto done;
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}
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}
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/* Update the expiry counter if fs is busy */
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if (!may_umount_tree(path.mnt)) {
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struct autofs_info *ino = autofs4_dentry_ino(top);
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ino->last_used = jiffies;
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goto done;
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}
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status = 0;
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done:
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DPRINTK("returning = %d", status);
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path_put(&path);
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return status;
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}
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/*
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* Calculate next entry in top down tree traversal.
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* From next_mnt in namespace.c - elegant.
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*/
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static struct dentry *next_dentry(struct dentry *p, struct dentry *root)
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{
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struct list_head *next = p->d_subdirs.next;
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if (next == &p->d_subdirs) {
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while (1) {
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if (p == root)
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return NULL;
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next = p->d_u.d_child.next;
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if (next != &p->d_parent->d_subdirs)
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break;
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p = p->d_parent;
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}
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}
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return list_entry(next, struct dentry, d_u.d_child);
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}
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/*
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* Check a direct mount point for busyness.
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* Direct mounts have similar expiry semantics to tree mounts.
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* The tree is not busy iff no mountpoints are busy and there are no
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* autofs submounts.
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*/
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static int autofs4_direct_busy(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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DPRINTK("top %p %.*s",
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top, (int) top->d_name.len, top->d_name.name);
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/* If it's busy update the expiry counters */
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if (!may_umount_tree(mnt)) {
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struct autofs_info *ino = autofs4_dentry_ino(top);
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if (ino)
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ino->last_used = jiffies;
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return 1;
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}
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/* Timeout of a direct mount is determined by its top dentry */
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if (!autofs4_can_expire(top, timeout, do_now))
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return 1;
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return 0;
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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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*/
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static int autofs4_tree_busy(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 autofs_info *top_ino = autofs4_dentry_ino(top);
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struct dentry *p;
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DPRINTK("top %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 1;
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spin_lock(&dcache_lock);
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for (p = top; p; p = next_dentry(p, top)) {
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/* Negative dentry - give up */
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if (!simple_positive(p))
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continue;
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DPRINTK("dentry %p %.*s",
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p, (int) p->d_name.len, p->d_name.name);
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p = dget(p);
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spin_unlock(&dcache_lock);
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/*
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* Is someone visiting anywhere in the subtree ?
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* If there's no mount we need to check the usage
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* count for the autofs dentry.
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* If the fs is busy update the expiry counter.
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*/
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if (d_mountpoint(p)) {
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if (autofs4_mount_busy(mnt, p)) {
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top_ino->last_used = jiffies;
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dput(p);
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return 1;
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}
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} else {
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struct autofs_info *ino = autofs4_dentry_ino(p);
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unsigned int ino_count = atomic_read(&ino->count);
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/*
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* Clean stale dentries below that have not been
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* invalidated after a mount fail during lookup
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*/
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d_invalidate(p);
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/* allow for dget above and top is already dgot */
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if (p == top)
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ino_count += 2;
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else
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ino_count++;
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if (atomic_read(&p->d_count) > ino_count) {
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top_ino->last_used = jiffies;
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dput(p);
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return 1;
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}
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}
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dput(p);
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spin_lock(&dcache_lock);
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}
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spin_unlock(&dcache_lock);
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/* Timeout of a tree mount is ultimately determined by its top dentry */
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if (!autofs4_can_expire(top, timeout, do_now))
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return 1;
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return 0;
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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 *p;
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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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for (p = parent; p; p = next_dentry(p, parent)) {
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/* Negative dentry - give up */
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if (!simple_positive(p))
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continue;
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DPRINTK("dentry %p %.*s",
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p, (int) p->d_name.len, p->d_name.name);
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p = dget(p);
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spin_unlock(&dcache_lock);
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if (d_mountpoint(p)) {
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/* Can we umount this guy */
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if (autofs4_mount_busy(mnt, p))
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goto cont;
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/* Can we expire this guy */
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if (autofs4_can_expire(p, timeout, do_now))
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return p;
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}
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cont:
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dput(p);
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spin_lock(&dcache_lock);
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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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/* Check if we can expire a direct mount (possibly a tree) */
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struct dentry *autofs4_expire_direct(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 = dget(sb->s_root);
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int do_now = how & AUTOFS_EXP_IMMEDIATE;
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if (!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(&sbi->fs_lock);
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if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
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struct autofs_info *ino = autofs4_dentry_ino(root);
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if (d_mountpoint(root)) {
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ino->flags |= AUTOFS_INF_MOUNTPOINT;
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root->d_mounted--;
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}
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ino->flags |= AUTOFS_INF_EXPIRING;
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autofs4_add_expiring(root);
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init_completion(&ino->expire_complete);
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spin_unlock(&sbi->fs_lock);
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return root;
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}
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spin_unlock(&sbi->fs_lock);
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dput(root);
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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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struct dentry *autofs4_expire_indirect(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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struct autofs_info *ino;
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unsigned int ino_count;
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if (!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_u.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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spin_lock(&sbi->fs_lock);
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ino = autofs4_dentry_ino(dentry);
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/*
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* Case 1: (i) indirect mount or top level pseudo direct mount
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* (autofs-4.1).
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* (ii) indirect mount with offset mount, check the "/"
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* offset (autofs-5.0+).
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*/
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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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/* Path walk currently on this dentry? */
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ino_count = atomic_read(&ino->count) + 2;
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if (atomic_read(&dentry->d_count) > ino_count)
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goto next;
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/* Can we umount this guy */
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if (autofs4_mount_busy(mnt, dentry))
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goto next;
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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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expired = dentry;
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goto found;
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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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/* Path walk currently on this dentry? */
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ino_count = atomic_read(&ino->count) + 1;
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if (atomic_read(&dentry->d_count) > ino_count)
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goto next;
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if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
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expired = dentry;
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goto found;
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}
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/*
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* Case 3: pseudo direct mount, expire individual leaves
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* (autofs-4.1).
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*/
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} else {
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/* Path walk currently on this dentry? */
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ino_count = atomic_read(&ino->count) + 1;
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if (atomic_read(&dentry->d_count) > ino_count)
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goto next;
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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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goto found;
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}
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}
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next:
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spin_unlock(&sbi->fs_lock);
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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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spin_unlock(&dcache_lock);
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return NULL;
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found:
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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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ino = autofs4_dentry_ino(expired);
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ino->flags |= AUTOFS_INF_EXPIRING;
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autofs4_add_expiring(expired);
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init_completion(&ino->expire_complete);
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spin_unlock(&sbi->fs_lock);
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spin_lock(&dcache_lock);
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list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
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spin_unlock(&dcache_lock);
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return expired;
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}
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int autofs4_expire_wait(struct dentry *dentry)
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{
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struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
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struct autofs_info *ino = autofs4_dentry_ino(dentry);
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int status;
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/* Block on any pending expire */
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spin_lock(&sbi->fs_lock);
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if (ino->flags & AUTOFS_INF_EXPIRING) {
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spin_unlock(&sbi->fs_lock);
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DPRINTK("waiting for expire %p name=%.*s",
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dentry, dentry->d_name.len, dentry->d_name.name);
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status = autofs4_wait(sbi, dentry, NFY_NONE);
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wait_for_completion(&ino->expire_complete);
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DPRINTK("expire done status=%d", status);
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if (d_unhashed(dentry) && IS_DEADDIR(dentry->d_inode))
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return -EAGAIN;
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return status;
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}
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spin_unlock(&sbi->fs_lock);
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|
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return 0;
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}
|
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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 autofs_info *ino;
|
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struct dentry *dentry;
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int ret = 0;
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|
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memset(&pkt,0,sizeof pkt);
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|
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pkt.hdr.proto_version = sbi->version;
|
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pkt.hdr.type = autofs_ptype_expire;
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|
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if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
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return -EAGAIN;
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|
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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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|
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if ( copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire)) )
|
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ret = -EFAULT;
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|
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spin_lock(&sbi->fs_lock);
|
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ino = autofs4_dentry_ino(dentry);
|
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ino->flags &= ~AUTOFS_INF_EXPIRING;
|
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autofs4_del_expiring(dentry);
|
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complete_all(&ino->expire_complete);
|
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spin_unlock(&sbi->fs_lock);
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|
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return ret;
|
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}
|
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|
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int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
|
|
struct autofs_sb_info *sbi, int when)
|
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{
|
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struct dentry *dentry;
|
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int ret = -EAGAIN;
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|
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if (autofs_type_trigger(sbi->type))
|
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dentry = autofs4_expire_direct(sb, mnt, sbi, when);
|
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else
|
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dentry = autofs4_expire_indirect(sb, mnt, sbi, when);
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|
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if (dentry) {
|
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struct autofs_info *ino = autofs4_dentry_ino(dentry);
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|
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/* This is synchronous because it makes the daemon a
|
|
little easier */
|
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ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
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|
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spin_lock(&sbi->fs_lock);
|
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if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
|
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sb->s_root->d_mounted++;
|
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ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
|
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}
|
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ino->flags &= ~AUTOFS_INF_EXPIRING;
|
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autofs4_del_expiring(dentry);
|
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complete_all(&ino->expire_complete);
|
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spin_unlock(&sbi->fs_lock);
|
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dput(dentry);
|
|
}
|
|
|
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return ret;
|
|
}
|
|
|
|
/* 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)
|
|
{
|
|
int do_now = 0;
|
|
|
|
if (arg && get_user(do_now, arg))
|
|
return -EFAULT;
|
|
|
|
return autofs4_do_expire_multi(sb, mnt, sbi, do_now);
|
|
}
|
|
|