From a4633357ac610cd2f8740e28a31fc148a7960421 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 10 Oct 2010 05:36:26 -0400 Subject: [PATCH] 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 Signed-off-by: Al Viro --- fs/dcache.c | 49 +++++++++++++++++++++++-------------------------- 1 file changed, 23 insertions(+), 26 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index e987ad576a39..cc2b93802179 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -133,37 +133,34 @@ static void dentry_iput(struct dentry * dentry) } /* - * 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 @@ void dput(struct dentry *dentry) /* 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 @@ EXPORT_SYMBOL(d_invalidate); 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 @@ static void prune_one_dentry(struct dentry * dentry) 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 @@ static void shrink_dentry_list(struct list_head *list) 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 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) /* 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 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry) 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 @@ static int select_parent(struct dentry * parent) 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); } /* -- GitLab