610 lines
14 KiB
C
610 lines
14 KiB
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;
|
|
|
|
if (!do_now) {
|
|
/* Too young to die */
|
|
if (!timeout || time_after(ino->last_used + timeout, now))
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/* Check a mount point for busyness */
|
|
static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
|
|
{
|
|
struct dentry *top = dentry;
|
|
struct path path = {.mnt = mnt, .dentry = dentry};
|
|
int status = 1;
|
|
|
|
pr_debug("dentry %p %pd\n", dentry, dentry);
|
|
|
|
path_get(&path);
|
|
|
|
if (!follow_down_one(&path))
|
|
goto done;
|
|
|
|
if (is_autofs4_dentry(path.dentry)) {
|
|
struct autofs_sb_info *sbi = autofs4_sbi(path.dentry->d_sb);
|
|
|
|
/* This is an autofs submount, we can't expire it */
|
|
if (autofs_type_indirect(sbi->type))
|
|
goto done;
|
|
}
|
|
|
|
/* Update the expiry counter if fs is busy */
|
|
if (!may_umount_tree(path.mnt)) {
|
|
struct autofs_info *ino;
|
|
|
|
ino = autofs4_dentry_ino(top);
|
|
ino->last_used = jiffies;
|
|
goto done;
|
|
}
|
|
|
|
status = 0;
|
|
done:
|
|
pr_debug("returning = %d\n", status);
|
|
path_put(&path);
|
|
return status;
|
|
}
|
|
|
|
/*
|
|
* Calculate and dget next entry in the subdirs list under root.
|
|
*/
|
|
static struct dentry *get_next_positive_subdir(struct dentry *prev,
|
|
struct dentry *root)
|
|
{
|
|
struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
|
|
struct list_head *next;
|
|
struct dentry *q;
|
|
|
|
spin_lock(&sbi->lookup_lock);
|
|
spin_lock(&root->d_lock);
|
|
|
|
if (prev)
|
|
next = prev->d_child.next;
|
|
else {
|
|
prev = dget_dlock(root);
|
|
next = prev->d_subdirs.next;
|
|
}
|
|
|
|
cont:
|
|
if (next == &root->d_subdirs) {
|
|
spin_unlock(&root->d_lock);
|
|
spin_unlock(&sbi->lookup_lock);
|
|
dput(prev);
|
|
return NULL;
|
|
}
|
|
|
|
q = list_entry(next, struct dentry, d_child);
|
|
|
|
spin_lock_nested(&q->d_lock, DENTRY_D_LOCK_NESTED);
|
|
/* Already gone or negative dentry (under construction) - try next */
|
|
if (!d_count(q) || !simple_positive(q)) {
|
|
spin_unlock(&q->d_lock);
|
|
next = q->d_child.next;
|
|
goto cont;
|
|
}
|
|
dget_dlock(q);
|
|
spin_unlock(&q->d_lock);
|
|
spin_unlock(&root->d_lock);
|
|
spin_unlock(&sbi->lookup_lock);
|
|
|
|
dput(prev);
|
|
|
|
return q;
|
|
}
|
|
|
|
/*
|
|
* Calculate and dget next entry in top down tree traversal.
|
|
*/
|
|
static struct dentry *get_next_positive_dentry(struct dentry *prev,
|
|
struct dentry *root)
|
|
{
|
|
struct autofs_sb_info *sbi = autofs4_sbi(root->d_sb);
|
|
struct list_head *next;
|
|
struct dentry *p, *ret;
|
|
|
|
if (prev == NULL)
|
|
return dget(root);
|
|
|
|
spin_lock(&sbi->lookup_lock);
|
|
relock:
|
|
p = prev;
|
|
spin_lock(&p->d_lock);
|
|
again:
|
|
next = p->d_subdirs.next;
|
|
if (next == &p->d_subdirs) {
|
|
while (1) {
|
|
struct dentry *parent;
|
|
|
|
if (p == root) {
|
|
spin_unlock(&p->d_lock);
|
|
spin_unlock(&sbi->lookup_lock);
|
|
dput(prev);
|
|
return NULL;
|
|
}
|
|
|
|
parent = p->d_parent;
|
|
if (!spin_trylock(&parent->d_lock)) {
|
|
spin_unlock(&p->d_lock);
|
|
cpu_relax();
|
|
goto relock;
|
|
}
|
|
spin_unlock(&p->d_lock);
|
|
next = p->d_child.next;
|
|
p = parent;
|
|
if (next != &parent->d_subdirs)
|
|
break;
|
|
}
|
|
}
|
|
ret = list_entry(next, struct dentry, d_child);
|
|
|
|
spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
|
|
/* Negative dentry - try next */
|
|
if (!simple_positive(ret)) {
|
|
spin_unlock(&p->d_lock);
|
|
lock_set_subclass(&ret->d_lock.dep_map, 0, _RET_IP_);
|
|
p = ret;
|
|
goto again;
|
|
}
|
|
dget_dlock(ret);
|
|
spin_unlock(&ret->d_lock);
|
|
spin_unlock(&p->d_lock);
|
|
spin_unlock(&sbi->lookup_lock);
|
|
|
|
dput(prev);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
pr_debug("top %p %pd\n", top, top);
|
|
|
|
/* If it's busy update the expiry counters */
|
|
if (!may_umount_tree(mnt)) {
|
|
struct autofs_info *ino;
|
|
|
|
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;
|
|
|
|
pr_debug("top %p %pd\n", top, top);
|
|
|
|
/* Negative dentry - give up */
|
|
if (!simple_positive(top))
|
|
return 1;
|
|
|
|
p = NULL;
|
|
while ((p = get_next_positive_dentry(p, top))) {
|
|
pr_debug("dentry %p %pd\n", p, p);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/* allow for dget above and top is already dgot */
|
|
if (p == top)
|
|
ino_count += 2;
|
|
else
|
|
ino_count++;
|
|
|
|
if (d_count(p) > ino_count) {
|
|
top_ino->last_used = jiffies;
|
|
dput(p);
|
|
return 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* 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;
|
|
|
|
pr_debug("parent %p %pd\n", parent, parent);
|
|
|
|
p = NULL;
|
|
while ((p = get_next_positive_dentry(p, parent))) {
|
|
pr_debug("dentry %p %pd\n", p, p);
|
|
|
|
if (d_mountpoint(p)) {
|
|
/* Can we umount this guy */
|
|
if (autofs4_mount_busy(mnt, p))
|
|
continue;
|
|
|
|
/* Can we expire this guy */
|
|
if (autofs4_can_expire(p, timeout, do_now))
|
|
return p;
|
|
}
|
|
}
|
|
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;
|
|
struct autofs_info *ino;
|
|
|
|
if (!root)
|
|
return NULL;
|
|
|
|
now = jiffies;
|
|
timeout = sbi->exp_timeout;
|
|
|
|
spin_lock(&sbi->fs_lock);
|
|
ino = autofs4_dentry_ino(root);
|
|
/* No point expiring a pending mount */
|
|
if (ino->flags & AUTOFS_INF_PENDING)
|
|
goto out;
|
|
if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
|
|
ino->flags |= AUTOFS_INF_NO_RCU;
|
|
spin_unlock(&sbi->fs_lock);
|
|
synchronize_rcu();
|
|
spin_lock(&sbi->fs_lock);
|
|
if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
|
|
ino->flags |= AUTOFS_INF_EXPIRING;
|
|
smp_mb();
|
|
ino->flags &= ~AUTOFS_INF_NO_RCU;
|
|
init_completion(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
return root;
|
|
}
|
|
ino->flags &= ~AUTOFS_INF_NO_RCU;
|
|
}
|
|
out:
|
|
spin_unlock(&sbi->fs_lock);
|
|
dput(root);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/* Check if 'dentry' should expire, or return a nearby
|
|
* dentry that is suitable.
|
|
* If returned dentry is different from arg dentry,
|
|
* then a dget() reference was taken, else not.
|
|
*/
|
|
static struct dentry *should_expire(struct dentry *dentry,
|
|
struct vfsmount *mnt,
|
|
unsigned long timeout,
|
|
int how)
|
|
{
|
|
int do_now = how & AUTOFS_EXP_IMMEDIATE;
|
|
int exp_leaves = how & AUTOFS_EXP_LEAVES;
|
|
struct autofs_info *ino = autofs4_dentry_ino(dentry);
|
|
unsigned int ino_count;
|
|
|
|
/* No point expiring a pending mount */
|
|
if (ino->flags & AUTOFS_INF_PENDING)
|
|
return NULL;
|
|
|
|
/*
|
|
* 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)) {
|
|
pr_debug("checking mountpoint %p %pd\n", dentry, dentry);
|
|
|
|
/* Can we umount this guy */
|
|
if (autofs4_mount_busy(mnt, dentry))
|
|
return NULL;
|
|
|
|
/* Can we expire this guy */
|
|
if (autofs4_can_expire(dentry, timeout, do_now))
|
|
return dentry;
|
|
return NULL;
|
|
}
|
|
|
|
if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
|
|
pr_debug("checking symlink %p %pd\n", dentry, dentry);
|
|
/*
|
|
* A symlink can't be "busy" in the usual sense so
|
|
* just check last used for expire timeout.
|
|
*/
|
|
if (autofs4_can_expire(dentry, timeout, do_now))
|
|
return dentry;
|
|
return NULL;
|
|
}
|
|
|
|
if (simple_empty(dentry))
|
|
return NULL;
|
|
|
|
/* 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 (d_count(dentry) > ino_count)
|
|
return NULL;
|
|
|
|
if (!autofs4_tree_busy(mnt, dentry, timeout, do_now))
|
|
return dentry;
|
|
/*
|
|
* Case 3: pseudo direct mount, expire individual leaves
|
|
* (autofs-4.1).
|
|
*/
|
|
} else {
|
|
/* Path walk currently on this dentry? */
|
|
struct dentry *expired;
|
|
|
|
ino_count = atomic_read(&ino->count) + 1;
|
|
if (d_count(dentry) > ino_count)
|
|
return NULL;
|
|
|
|
expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
|
|
if (expired) {
|
|
if (expired == dentry)
|
|
dput(dentry);
|
|
return expired;
|
|
}
|
|
}
|
|
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
|
|
*/
|
|
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 *dentry;
|
|
struct dentry *expired;
|
|
struct autofs_info *ino;
|
|
|
|
if (!root)
|
|
return NULL;
|
|
|
|
now = jiffies;
|
|
timeout = sbi->exp_timeout;
|
|
|
|
dentry = NULL;
|
|
while ((dentry = get_next_positive_subdir(dentry, root))) {
|
|
spin_lock(&sbi->fs_lock);
|
|
ino = autofs4_dentry_ino(dentry);
|
|
if (ino->flags & AUTOFS_INF_NO_RCU)
|
|
expired = NULL;
|
|
else
|
|
expired = should_expire(dentry, mnt, timeout, how);
|
|
if (!expired) {
|
|
spin_unlock(&sbi->fs_lock);
|
|
continue;
|
|
}
|
|
ino = autofs4_dentry_ino(expired);
|
|
ino->flags |= AUTOFS_INF_NO_RCU;
|
|
spin_unlock(&sbi->fs_lock);
|
|
synchronize_rcu();
|
|
spin_lock(&sbi->fs_lock);
|
|
if (should_expire(expired, mnt, timeout, how)) {
|
|
if (expired != dentry)
|
|
dput(dentry);
|
|
goto found;
|
|
}
|
|
|
|
ino->flags &= ~AUTOFS_INF_NO_RCU;
|
|
if (expired != dentry)
|
|
dput(expired);
|
|
spin_unlock(&sbi->fs_lock);
|
|
}
|
|
return NULL;
|
|
|
|
found:
|
|
pr_debug("returning %p %pd\n", expired, expired);
|
|
ino->flags |= AUTOFS_INF_EXPIRING;
|
|
smp_mb();
|
|
ino->flags &= ~AUTOFS_INF_NO_RCU;
|
|
init_completion(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
spin_lock(&sbi->lookup_lock);
|
|
spin_lock(&expired->d_parent->d_lock);
|
|
spin_lock_nested(&expired->d_lock, DENTRY_D_LOCK_NESTED);
|
|
list_move(&expired->d_parent->d_subdirs, &expired->d_child);
|
|
spin_unlock(&expired->d_lock);
|
|
spin_unlock(&expired->d_parent->d_lock);
|
|
spin_unlock(&sbi->lookup_lock);
|
|
return expired;
|
|
}
|
|
|
|
int autofs4_expire_wait(struct dentry *dentry, int rcu_walk)
|
|
{
|
|
struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
|
|
struct autofs_info *ino = autofs4_dentry_ino(dentry);
|
|
int status;
|
|
|
|
/* Block on any pending expire */
|
|
if (!(ino->flags & (AUTOFS_INF_EXPIRING | AUTOFS_INF_NO_RCU)))
|
|
return 0;
|
|
if (rcu_walk)
|
|
return -ECHILD;
|
|
|
|
spin_lock(&sbi->fs_lock);
|
|
if (ino->flags & AUTOFS_INF_EXPIRING) {
|
|
spin_unlock(&sbi->fs_lock);
|
|
|
|
pr_debug("waiting for expire %p name=%pd\n", dentry, dentry);
|
|
|
|
status = autofs4_wait(sbi, dentry, NFY_NONE);
|
|
wait_for_completion(&ino->expire_complete);
|
|
|
|
pr_debug("expire done status=%d\n", status);
|
|
|
|
if (d_unhashed(dentry))
|
|
return -EAGAIN;
|
|
|
|
return status;
|
|
}
|
|
spin_unlock(&sbi->fs_lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* 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;
|
|
|
|
dentry = autofs4_expire_indirect(sb, mnt, sbi, 0);
|
|
if (!dentry)
|
|
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);
|
|
/* avoid rapid-fire expire attempts if expiry fails */
|
|
ino->last_used = now;
|
|
ino->flags &= ~AUTOFS_INF_EXPIRING;
|
|
complete_all(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
|
|
struct autofs_sb_info *sbi, int when)
|
|
{
|
|
struct dentry *dentry;
|
|
int ret = -EAGAIN;
|
|
|
|
if (autofs_type_trigger(sbi->type))
|
|
dentry = autofs4_expire_direct(sb, mnt, sbi, when);
|
|
else
|
|
dentry = autofs4_expire_indirect(sb, mnt, sbi, when);
|
|
|
|
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);
|
|
/* avoid rapid-fire expire attempts if expiry fails */
|
|
ino->last_used = now;
|
|
ino->flags &= ~AUTOFS_INF_EXPIRING;
|
|
complete_all(&ino->expire_complete);
|
|
spin_unlock(&sbi->fs_lock);
|
|
dput(dentry);
|
|
}
|
|
|
|
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);
|
|
}
|
|
|