+++ /dev/null
-/*
- * 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 autofs_can_expire(struct dentry *dentry,
- unsigned long timeout, int do_now)
-{
- struct autofs_info *ino = autofs_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 autofs_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_autofs_dentry(path.dentry)) {
- struct autofs_sb_info *sbi = autofs_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 = autofs_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 = autofs_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 = autofs_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 autofs_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 = autofs_dentry_ino(top);
- if (ino)
- ino->last_used = jiffies;
- return 1;
- }
-
- /* Timeout of a direct mount is determined by its top dentry */
- if (!autofs_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 autofs_tree_busy(struct vfsmount *mnt,
- struct dentry *top,
- unsigned long timeout,
- int do_now)
-{
- struct autofs_info *top_ino = autofs_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 (autofs_mount_busy(mnt, p)) {
- top_ino->last_used = jiffies;
- dput(p);
- return 1;
- }
- } else {
- struct autofs_info *ino = autofs_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 (!autofs_can_expire(top, timeout, do_now))
- return 1;
-
- return 0;
-}
-
-static struct dentry *autofs_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 (autofs_mount_busy(mnt, p))
- continue;
-
- /* Can we expire this guy */
- if (autofs_can_expire(p, timeout, do_now))
- return p;
- }
- }
- return NULL;
-}
-
-/* Check if we can expire a direct mount (possibly a tree) */
-struct dentry *autofs_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;
-
- if (!autofs_direct_busy(mnt, root, timeout, do_now)) {
- spin_lock(&sbi->fs_lock);
- ino = autofs_dentry_ino(root);
- /* No point expiring a pending mount */
- if (ino->flags & AUTOFS_INF_PENDING) {
- spin_unlock(&sbi->fs_lock);
- goto out;
- }
- ino->flags |= AUTOFS_INF_WANT_EXPIRE;
- spin_unlock(&sbi->fs_lock);
- synchronize_rcu();
- if (!autofs_direct_busy(mnt, root, timeout, do_now)) {
- spin_lock(&sbi->fs_lock);
- ino->flags |= AUTOFS_INF_EXPIRING;
- init_completion(&ino->expire_complete);
- spin_unlock(&sbi->fs_lock);
- return root;
- }
- spin_lock(&sbi->fs_lock);
- ino->flags &= ~AUTOFS_INF_WANT_EXPIRE;
- spin_unlock(&sbi->fs_lock);
- }
-out:
- 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 = autofs_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 (autofs_mount_busy(mnt, dentry))
- return NULL;
-
- /* Can we expire this guy */
- if (autofs_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 (autofs_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 (!autofs_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 = autofs_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 *autofs_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 dentry *found;
- struct autofs_info *ino;
-
- if (!root)
- return NULL;
-
- now = jiffies;
- timeout = sbi->exp_timeout;
-
- dentry = NULL;
- while ((dentry = get_next_positive_subdir(dentry, root))) {
- int flags = how;
-
- spin_lock(&sbi->fs_lock);
- ino = autofs_dentry_ino(dentry);
- if (ino->flags & AUTOFS_INF_WANT_EXPIRE) {
- spin_unlock(&sbi->fs_lock);
- continue;
- }
- spin_unlock(&sbi->fs_lock);
-
- expired = should_expire(dentry, mnt, timeout, flags);
- if (!expired)
- continue;
-
- spin_lock(&sbi->fs_lock);
- ino = autofs_dentry_ino(expired);
- ino->flags |= AUTOFS_INF_WANT_EXPIRE;
- spin_unlock(&sbi->fs_lock);
- synchronize_rcu();
-
- /* Make sure a reference is not taken on found if
- * things have changed.
- */
- flags &= ~AUTOFS_EXP_LEAVES;
- found = should_expire(expired, mnt, timeout, how);
- if (!found || found != expired)
- /* Something has changed, continue */
- goto next;
-
- if (expired != dentry)
- dput(dentry);
-
- spin_lock(&sbi->fs_lock);
- goto found;
-next:
- spin_lock(&sbi->fs_lock);
- ino->flags &= ~AUTOFS_INF_WANT_EXPIRE;
- spin_unlock(&sbi->fs_lock);
- if (expired != dentry)
- dput(expired);
- }
- return NULL;
-
-found:
- pr_debug("returning %p %pd\n", expired, expired);
- ino->flags |= AUTOFS_INF_EXPIRING;
- init_completion(&ino->expire_complete);
- spin_unlock(&sbi->fs_lock);
- return expired;
-}
-
-int autofs_expire_wait(const struct path *path, int rcu_walk)
-{
- struct dentry *dentry = path->dentry;
- struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
- struct autofs_info *ino = autofs_dentry_ino(dentry);
- int status;
- int state;
-
- /* Block on any pending expire */
- if (!(ino->flags & AUTOFS_INF_WANT_EXPIRE))
- return 0;
- if (rcu_walk)
- return -ECHILD;
-
-retry:
- spin_lock(&sbi->fs_lock);
- state = ino->flags & (AUTOFS_INF_WANT_EXPIRE | AUTOFS_INF_EXPIRING);
- if (state == AUTOFS_INF_WANT_EXPIRE) {
- spin_unlock(&sbi->fs_lock);
- /*
- * Possibly being selected for expire, wait until
- * it's selected or not.
- */
- schedule_timeout_uninterruptible(HZ/10);
- goto retry;
- }
- if (state & AUTOFS_INF_EXPIRING) {
- spin_unlock(&sbi->fs_lock);
-
- pr_debug("waiting for expire %p name=%pd\n", dentry, dentry);
-
- status = autofs_wait(sbi, path, 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 autofs_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 = autofs_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 = autofs_dentry_ino(dentry);
- /* avoid rapid-fire expire attempts if expiry fails */
- ino->last_used = now;
- ino->flags &= ~(AUTOFS_INF_EXPIRING|AUTOFS_INF_WANT_EXPIRE);
- complete_all(&ino->expire_complete);
- spin_unlock(&sbi->fs_lock);
-
- return ret;
-}
-
-int autofs_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 = autofs_expire_direct(sb, mnt, sbi, when);
- else
- dentry = autofs_expire_indirect(sb, mnt, sbi, when);
-
- if (dentry) {
- struct autofs_info *ino = autofs_dentry_ino(dentry);
- const struct path path = { .mnt = mnt, .dentry = dentry };
-
- /* This is synchronous because it makes the daemon a
- * little easier
- */
- ret = autofs_wait(sbi, &path, NFY_EXPIRE);
-
- spin_lock(&sbi->fs_lock);
- /* avoid rapid-fire expire attempts if expiry fails */
- ino->last_used = now;
- ino->flags &= ~(AUTOFS_INF_EXPIRING|AUTOFS_INF_WANT_EXPIRE);
- 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 autofs_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 autofs_do_expire_multi(sb, mnt, sbi, do_now);
-}
-
projects / linux-2.6-block.git / blobdiff