fs: clean up dentry lru modification
Always do a list_del_init on the LRU to make sure the list_empty invariant for
not beeing on the LRU always holds true, and fold dentry_lru_del_init into
dentry_lru_del. Replace the dentry_lru_add_tail primitive with a
dentry_lru_move_tail operations that simpler when the dentry already is one
the list, which is always is. Move the list_empty into dentry_lru_add to
fit the scheme of the other lru helpers, and simplify locking once we
move to a separate LRU lock.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/dcache.c b/fs/dcache.c
index e987ad5..cc2b938 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -133,37 +133,34 @@
}
/*
- * dentry_lru_(add|add_tail|del|del_init) must be called with dcache_lock held.
+ * dentry_lru_(add|del|move_tail) must be called with dcache_lock held.
*/
static void dentry_lru_add(struct dentry *dentry)
{
- list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
- dentry->d_sb->s_nr_dentry_unused++;
- percpu_counter_inc(&nr_dentry_unused);
-}
-
-static void dentry_lru_add_tail(struct dentry *dentry)
-{
- list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
- dentry->d_sb->s_nr_dentry_unused++;
- percpu_counter_inc(&nr_dentry_unused);
+ if (list_empty(&dentry->d_lru)) {
+ list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+ dentry->d_sb->s_nr_dentry_unused++;
+ percpu_counter_inc(&nr_dentry_unused);
+ }
}
static void dentry_lru_del(struct dentry *dentry)
{
if (!list_empty(&dentry->d_lru)) {
- list_del(&dentry->d_lru);
+ list_del_init(&dentry->d_lru);
dentry->d_sb->s_nr_dentry_unused--;
percpu_counter_dec(&nr_dentry_unused);
}
}
-static void dentry_lru_del_init(struct dentry *dentry)
+static void dentry_lru_move_tail(struct dentry *dentry)
{
- if (likely(!list_empty(&dentry->d_lru))) {
- list_del_init(&dentry->d_lru);
- dentry->d_sb->s_nr_dentry_unused--;
- percpu_counter_dec(&nr_dentry_unused);
+ if (list_empty(&dentry->d_lru)) {
+ list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
+ dentry->d_sb->s_nr_dentry_unused++;
+ percpu_counter_inc(&nr_dentry_unused);
+ } else {
+ list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru);
}
}
@@ -253,8 +250,7 @@
/* Otherwise leave it cached and ensure it's on the LRU */
dentry->d_flags |= DCACHE_REFERENCED;
- if (list_empty(&dentry->d_lru))
- dentry_lru_add(dentry);
+ dentry_lru_add(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
@@ -333,7 +329,7 @@
static inline struct dentry * __dget_locked(struct dentry *dentry)
{
atomic_inc(&dentry->d_count);
- dentry_lru_del_init(dentry);
+ dentry_lru_del(dentry);
return dentry;
}
@@ -452,7 +448,7 @@
if (dentry->d_op && dentry->d_op->d_delete)
dentry->d_op->d_delete(dentry);
- dentry_lru_del_init(dentry);
+ dentry_lru_del(dentry);
__d_drop(dentry);
dentry = d_kill(dentry);
spin_lock(&dcache_lock);
@@ -465,7 +461,7 @@
while (!list_empty(list)) {
dentry = list_entry(list->prev, struct dentry, d_lru);
- dentry_lru_del_init(dentry);
+ dentry_lru_del(dentry);
/*
* We found an inuse dentry which was not removed from
@@ -650,7 +646,7 @@
/* detach this root from the system */
spin_lock(&dcache_lock);
- dentry_lru_del_init(dentry);
+ dentry_lru_del(dentry);
__d_drop(dentry);
spin_unlock(&dcache_lock);
@@ -664,7 +660,7 @@
spin_lock(&dcache_lock);
list_for_each_entry(loop, &dentry->d_subdirs,
d_u.d_child) {
- dentry_lru_del_init(loop);
+ dentry_lru_del(loop);
__d_drop(loop);
cond_resched_lock(&dcache_lock);
}
@@ -841,14 +837,15 @@
struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
next = tmp->next;
- dentry_lru_del_init(dentry);
/*
* move only zero ref count dentries to the end
* of the unused list for prune_dcache
*/
if (!atomic_read(&dentry->d_count)) {
- dentry_lru_add_tail(dentry);
+ dentry_lru_move_tail(dentry);
found++;
+ } else {
+ dentry_lru_del(dentry);
}
/*