Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull dcache updates from Al Viro: "This is the first part of dealing with livelocks etc around shrink_dcache_parent()." * 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: restore cond_resched() in shrink_dcache_parent() dput(): turn into explicit while() loop dcache: move cond_resched() into the end of __dentry_kill() d_walk(): kill 'finish' callback d_invalidate(): unhash immediately
This commit is contained in:
Linus Torvalds
commit
06c86e66d6
122
fs/dcache.c
122
fs/dcache.c
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@ -580,6 +580,7 @@ static void __dentry_kill(struct dentry *dentry)
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spin_unlock(&dentry->d_lock);
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if (likely(can_free))
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dentry_free(dentry);
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cond_resched();
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}
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static struct dentry *__lock_parent(struct dentry *dentry)
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@ -827,30 +828,24 @@ static inline bool fast_dput(struct dentry *dentry)
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*/
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void dput(struct dentry *dentry)
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{
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if (unlikely(!dentry))
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return;
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while (dentry) {
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might_sleep();
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repeat:
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might_sleep();
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rcu_read_lock();
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if (likely(fast_dput(dentry))) {
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rcu_read_unlock();
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return;
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}
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rcu_read_lock();
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if (likely(fast_dput(dentry))) {
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/* Slow case: now with the dentry lock held */
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rcu_read_unlock();
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return;
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}
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/* Slow case: now with the dentry lock held */
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rcu_read_unlock();
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if (likely(retain_dentry(dentry))) {
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spin_unlock(&dentry->d_lock);
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return;
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}
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if (likely(retain_dentry(dentry))) {
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spin_unlock(&dentry->d_lock);
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return;
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}
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dentry = dentry_kill(dentry);
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if (dentry) {
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cond_resched();
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goto repeat;
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dentry = dentry_kill(dentry);
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}
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}
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EXPORT_SYMBOL(dput);
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@ -1052,8 +1047,6 @@ static void shrink_dentry_list(struct list_head *list)
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while (!list_empty(list)) {
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struct dentry *dentry, *parent;
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cond_resched();
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dentry = list_entry(list->prev, struct dentry, d_lru);
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spin_lock(&dentry->d_lock);
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rcu_read_lock();
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@ -1230,13 +1223,11 @@ enum d_walk_ret {
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* @parent: start of walk
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* @data: data passed to @enter() and @finish()
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* @enter: callback when first entering the dentry
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* @finish: callback when successfully finished the walk
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*
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* The @enter() and @finish() callbacks are called with d_lock held.
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* The @enter() callbacks are called with d_lock held.
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*/
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static void d_walk(struct dentry *parent, void *data,
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enum d_walk_ret (*enter)(void *, struct dentry *),
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void (*finish)(void *))
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enum d_walk_ret (*enter)(void *, struct dentry *))
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{
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struct dentry *this_parent;
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struct list_head *next;
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@ -1325,8 +1316,6 @@ ascend:
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if (need_seqretry(&rename_lock, seq))
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goto rename_retry;
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rcu_read_unlock();
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if (finish)
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finish(data);
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out_unlock:
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spin_unlock(&this_parent->d_lock);
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@ -1375,7 +1364,7 @@ int path_has_submounts(const struct path *parent)
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struct check_mount data = { .mnt = parent->mnt, .mounted = 0 };
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read_seqlock_excl(&mount_lock);
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d_walk(parent->dentry, &data, path_check_mount, NULL);
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d_walk(parent->dentry, &data, path_check_mount);
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read_sequnlock_excl(&mount_lock);
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return data.mounted;
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@ -1483,11 +1472,16 @@ void shrink_dcache_parent(struct dentry *parent)
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data.start = parent;
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data.found = 0;
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d_walk(parent, &data, select_collect, NULL);
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d_walk(parent, &data, select_collect);
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if (!list_empty(&data.dispose)) {
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shrink_dentry_list(&data.dispose);
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continue;
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}
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cond_resched();
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if (!data.found)
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break;
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shrink_dentry_list(&data.dispose);
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}
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}
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EXPORT_SYMBOL(shrink_dcache_parent);
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@ -1518,7 +1512,7 @@ static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
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static void do_one_tree(struct dentry *dentry)
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{
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shrink_dcache_parent(dentry);
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d_walk(dentry, dentry, umount_check, NULL);
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d_walk(dentry, dentry, umount_check);
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d_drop(dentry);
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dput(dentry);
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}
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@ -1542,78 +1536,48 @@ void shrink_dcache_for_umount(struct super_block *sb)
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}
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}
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struct detach_data {
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struct select_data select;
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struct dentry *mountpoint;
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};
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static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry)
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static enum d_walk_ret find_submount(void *_data, struct dentry *dentry)
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{
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struct detach_data *data = _data;
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struct dentry **victim = _data;
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if (d_mountpoint(dentry)) {
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__dget_dlock(dentry);
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data->mountpoint = dentry;
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*victim = dentry;
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return D_WALK_QUIT;
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}
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return select_collect(&data->select, dentry);
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}
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static void check_and_drop(void *_data)
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{
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struct detach_data *data = _data;
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if (!data->mountpoint && list_empty(&data->select.dispose))
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__d_drop(data->select.start);
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return D_WALK_CONTINUE;
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}
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/**
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* d_invalidate - detach submounts, prune dcache, and drop
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* @dentry: dentry to invalidate (aka detach, prune and drop)
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*
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* no dcache lock.
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*
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* The final d_drop is done as an atomic operation relative to
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* rename_lock ensuring there are no races with d_set_mounted. This
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* ensures there are no unhashed dentries on the path to a mountpoint.
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*/
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void d_invalidate(struct dentry *dentry)
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{
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/*
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* If it's already been dropped, return OK.
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*/
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bool had_submounts = false;
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spin_lock(&dentry->d_lock);
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if (d_unhashed(dentry)) {
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spin_unlock(&dentry->d_lock);
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return;
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}
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__d_drop(dentry);
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spin_unlock(&dentry->d_lock);
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/* Negative dentries can be dropped without further checks */
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if (!dentry->d_inode) {
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d_drop(dentry);
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if (!dentry->d_inode)
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return;
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}
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shrink_dcache_parent(dentry);
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for (;;) {
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struct detach_data data;
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data.mountpoint = NULL;
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INIT_LIST_HEAD(&data.select.dispose);
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data.select.start = dentry;
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data.select.found = 0;
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d_walk(dentry, &data, detach_and_collect, check_and_drop);
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if (!list_empty(&data.select.dispose))
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shrink_dentry_list(&data.select.dispose);
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else if (!data.mountpoint)
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struct dentry *victim = NULL;
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d_walk(dentry, &victim, find_submount);
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if (!victim) {
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if (had_submounts)
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shrink_dcache_parent(dentry);
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return;
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if (data.mountpoint) {
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detach_mounts(data.mountpoint);
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dput(data.mountpoint);
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}
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had_submounts = true;
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detach_mounts(victim);
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dput(victim);
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}
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}
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EXPORT_SYMBOL(d_invalidate);
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@ -3134,7 +3098,7 @@ static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
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void d_genocide(struct dentry *parent)
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{
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d_walk(parent, parent, d_genocide_kill, NULL);
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d_walk(parent, parent, d_genocide_kill);
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}
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EXPORT_SYMBOL(d_genocide);
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