forked from luck/tmp_suning_uos_patched
6e60a9ab5f
For direct and offset type mounts that are covered by another mount we cannot check the AUTOFS_INF_EXPIRING flag during a path walk which leads to lookups walking into an expiring mount while it is being expired. For example, for the direct multi-mount map entry with a couple of offsets: /race/mm1 / <server1>:/<path1> /om1 <server2>:/<path2> /om2 <server1>:/<path3> an autofs trigger mount is mounted on /race/mm1 and when accessed it is over mounted and trigger mounts made for /race/mm1/om1 and /race/mm1/om2. So it isn't possible for path walks to see the expiring flag at all and they happily walk into the file system while it is expiring. When expiring these mounts follow_down() must stop at the autofs mount and all processes must block in the ->follow_link() method (except the daemon) until the expire is complete. This is done by decrementing the d_mounted field of the autofs trigger mount root dentry until the expire is completed. In ->follow_link() all processes wait on the expire and the mount following is completed for the daemon until the expire is complete. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
479 lines
11 KiB
C
479 lines
11 KiB
C
/* -*- 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 (!autofs4_follow_mount(&mnt, &dentry))
|
|
goto done;
|
|
|
|
/* This is an autofs submount, we can't expire it */
|
|
if (is_autofs4_dentry(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) */
|
|
static 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;
|
|
timeout = sbi->exp_timeout;
|
|
|
|
spin_lock(&sbi->fs_lock);
|
|
if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
|
|
struct autofs_info *ino = autofs4_dentry_ino(root);
|
|
if (d_mountpoint(root)) {
|
|
ino->flags |= AUTOFS_INF_MOUNTPOINT;
|
|
root->d_mounted--;
|
|
}
|
|
ino->flags |= AUTOFS_INF_EXPIRING;
|
|
init_completion(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
return root;
|
|
}
|
|
spin_unlock(&sbi->fs_lock);
|
|
dput(root);
|
|
|
|
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_indirect(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;
|
|
struct autofs_info *ino;
|
|
unsigned int ino_count;
|
|
|
|
if (!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_u.d_child);
|
|
|
|
/* Negative dentry - give up */
|
|
if (!simple_positive(dentry)) {
|
|
next = next->next;
|
|
continue;
|
|
}
|
|
|
|
dentry = dget(dentry);
|
|
spin_unlock(&dcache_lock);
|
|
|
|
spin_lock(&sbi->fs_lock);
|
|
ino = autofs4_dentry_ino(dentry);
|
|
|
|
/*
|
|
* Case 1: (i) indirect mount or top level pseudo direct mount
|
|
* (autofs-4.1).
|
|
* (ii) indirect mount with offset mount, check the "/"
|
|
* offset (autofs-5.0+).
|
|
*/
|
|
if (d_mountpoint(dentry)) {
|
|
DPRINTK("checking mountpoint %p %.*s",
|
|
dentry, (int)dentry->d_name.len, dentry->d_name.name);
|
|
|
|
/* Path walk currently on this dentry? */
|
|
ino_count = atomic_read(&ino->count) + 2;
|
|
if (atomic_read(&dentry->d_count) > ino_count)
|
|
goto next;
|
|
|
|
/* Can we umount this guy */
|
|
if (autofs4_mount_busy(mnt, dentry))
|
|
goto next;
|
|
|
|
/* Can we expire this guy */
|
|
if (autofs4_can_expire(dentry, timeout, do_now)) {
|
|
expired = dentry;
|
|
goto found;
|
|
}
|
|
goto next;
|
|
}
|
|
|
|
if (simple_empty(dentry))
|
|
goto next;
|
|
|
|
/* Case 2: tree mount, expire iff entire tree is not busy */
|
|
if (!exp_leaves) {
|
|
/* Path walk currently on this dentry? */
|
|
ino_count = atomic_read(&ino->count) + 1;
|
|
if (atomic_read(&dentry->d_count) > ino_count)
|
|
goto next;
|
|
|
|
if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
|
|
expired = dentry;
|
|
goto found;
|
|
}
|
|
/*
|
|
* Case 3: pseudo direct mount, expire individual leaves
|
|
* (autofs-4.1).
|
|
*/
|
|
} else {
|
|
/* Path walk currently on this dentry? */
|
|
ino_count = atomic_read(&ino->count) + 1;
|
|
if (atomic_read(&dentry->d_count) > ino_count)
|
|
goto next;
|
|
|
|
expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
|
|
if (expired) {
|
|
dput(dentry);
|
|
goto found;
|
|
}
|
|
}
|
|
next:
|
|
spin_unlock(&sbi->fs_lock);
|
|
dput(dentry);
|
|
spin_lock(&dcache_lock);
|
|
next = next->next;
|
|
}
|
|
spin_unlock(&dcache_lock);
|
|
return NULL;
|
|
|
|
found:
|
|
DPRINTK("returning %p %.*s",
|
|
expired, (int)expired->d_name.len, expired->d_name.name);
|
|
ino = autofs4_dentry_ino(expired);
|
|
ino->flags |= AUTOFS_INF_EXPIRING;
|
|
init_completion(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
spin_lock(&dcache_lock);
|
|
list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
|
|
spin_unlock(&dcache_lock);
|
|
return expired;
|
|
}
|
|
|
|
/* 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 autofs_info *ino;
|
|
struct dentry *dentry;
|
|
int ret = 0;
|
|
|
|
memset(&pkt,0,sizeof pkt);
|
|
|
|
pkt.hdr.proto_version = sbi->version;
|
|
pkt.hdr.type = autofs_ptype_expire;
|
|
|
|
if ((dentry = autofs4_expire_indirect(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)) )
|
|
ret = -EFAULT;
|
|
|
|
spin_lock(&sbi->fs_lock);
|
|
ino = autofs4_dentry_ino(dentry);
|
|
ino->flags &= ~AUTOFS_INF_EXPIRING;
|
|
complete_all(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
|
|
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)
|
|
{
|
|
struct dentry *dentry;
|
|
int ret = -EAGAIN;
|
|
int do_now = 0;
|
|
|
|
if (arg && get_user(do_now, arg))
|
|
return -EFAULT;
|
|
|
|
if (sbi->type & AUTOFS_TYPE_DIRECT)
|
|
dentry = autofs4_expire_direct(sb, mnt, sbi, do_now);
|
|
else
|
|
dentry = autofs4_expire_indirect(sb, mnt, sbi, do_now);
|
|
|
|
if (dentry) {
|
|
struct autofs_info *ino = autofs4_dentry_ino(dentry);
|
|
|
|
/* This is synchronous because it makes the daemon a
|
|
little easier */
|
|
ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
|
|
|
|
spin_lock(&sbi->fs_lock);
|
|
if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
|
|
sb->s_root->d_mounted++;
|
|
ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
|
|
}
|
|
ino->flags &= ~AUTOFS_INF_EXPIRING;
|
|
complete_all(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
dput(dentry);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|