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-rw-r--r--fs/dcache.c100
-rw-r--r--fs/internal.h2
2 files changed, 85 insertions, 17 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index c435398f2c81..01b8cae41a71 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -861,6 +861,32 @@ void dput(struct dentry *dentry)
}
EXPORT_SYMBOL(dput);
+static void __dput_to_list(struct dentry *dentry, struct list_head *list)
+__must_hold(&dentry->d_lock)
+{
+ if (dentry->d_flags & DCACHE_SHRINK_LIST) {
+ /* let the owner of the list it's on deal with it */
+ --dentry->d_lockref.count;
+ } else {
+ if (dentry->d_flags & DCACHE_LRU_LIST)
+ d_lru_del(dentry);
+ if (!--dentry->d_lockref.count)
+ d_shrink_add(dentry, list);
+ }
+}
+
+void dput_to_list(struct dentry *dentry, struct list_head *list)
+{
+ rcu_read_lock();
+ if (likely(fast_dput(dentry))) {
+ rcu_read_unlock();
+ return;
+ }
+ rcu_read_unlock();
+ if (!retain_dentry(dentry))
+ __dput_to_list(dentry, list);
+ spin_unlock(&dentry->d_lock);
+}
/* This must be called with d_lock held */
static inline void __dget_dlock(struct dentry *dentry)
@@ -1067,7 +1093,7 @@ out:
return false;
}
-static void shrink_dentry_list(struct list_head *list)
+void shrink_dentry_list(struct list_head *list)
{
while (!list_empty(list)) {
struct dentry *dentry, *parent;
@@ -1089,18 +1115,9 @@ static void shrink_dentry_list(struct list_head *list)
rcu_read_unlock();
d_shrink_del(dentry);
parent = dentry->d_parent;
+ if (parent != dentry)
+ __dput_to_list(parent, list);
__dentry_kill(dentry);
- if (parent == dentry)
- continue;
- /*
- * We need to prune ancestors too. This is necessary to prevent
- * quadratic behavior of shrink_dcache_parent(), but is also
- * expected to be beneficial in reducing dentry cache
- * fragmentation.
- */
- dentry = parent;
- while (dentry && !lockref_put_or_lock(&dentry->d_lockref))
- dentry = dentry_kill(dentry);
}
}
@@ -1445,8 +1462,11 @@ out:
struct select_data {
struct dentry *start;
+ union {
+ long found;
+ struct dentry *victim;
+ };
struct list_head dispose;
- int found;
};
static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
@@ -1478,6 +1498,37 @@ out:
return ret;
}
+static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry)
+{
+ struct select_data *data = _data;
+ enum d_walk_ret ret = D_WALK_CONTINUE;
+
+ if (data->start == dentry)
+ goto out;
+
+ if (dentry->d_flags & DCACHE_SHRINK_LIST) {
+ if (!dentry->d_lockref.count) {
+ rcu_read_lock();
+ data->victim = dentry;
+ return D_WALK_QUIT;
+ }
+ } else {
+ if (dentry->d_flags & DCACHE_LRU_LIST)
+ d_lru_del(dentry);
+ if (!dentry->d_lockref.count)
+ d_shrink_add(dentry, &data->dispose);
+ }
+ /*
+ * We can return to the caller if we have found some (this
+ * ensures forward progress). We'll be coming back to find
+ * the rest.
+ */
+ if (!list_empty(&data->dispose))
+ ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
+out:
+ return ret;
+}
+
/**
* shrink_dcache_parent - prune dcache
* @parent: parent of entries to prune
@@ -1487,12 +1538,9 @@ out:
void shrink_dcache_parent(struct dentry *parent)
{
for (;;) {
- struct select_data data;
+ struct select_data data = {.start = parent};
INIT_LIST_HEAD(&data.dispose);
- data.start = parent;
- data.found = 0;
-
d_walk(parent, &data, select_collect);
if (!list_empty(&data.dispose)) {
@@ -1503,6 +1551,24 @@ void shrink_dcache_parent(struct dentry *parent)
cond_resched();
if (!data.found)
break;
+ data.victim = NULL;
+ d_walk(parent, &data, select_collect2);
+ if (data.victim) {
+ struct dentry *parent;
+ spin_lock(&data.victim->d_lock);
+ if (!shrink_lock_dentry(data.victim)) {
+ spin_unlock(&data.victim->d_lock);
+ rcu_read_unlock();
+ } else {
+ rcu_read_unlock();
+ parent = data.victim->d_parent;
+ if (parent != data.victim)
+ __dput_to_list(parent, &data.dispose);
+ __dentry_kill(data.victim);
+ }
+ }
+ if (!list_empty(&data.dispose))
+ shrink_dentry_list(&data.dispose);
}
}
EXPORT_SYMBOL(shrink_dcache_parent);
diff --git a/fs/internal.h b/fs/internal.h
index a48ef81be37d..dc317abe31b5 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -156,6 +156,8 @@ extern int d_set_mounted(struct dentry *dentry);
extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
extern struct dentry *d_alloc_cursor(struct dentry *);
extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
+extern void dput_to_list(struct dentry *, struct list_head *);
+extern void shrink_dentry_list(struct list_head *);
/*
* read_write.c