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fs: clean up dentry lru modification

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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>
This commit is contained in:
Christoph Hellwig 2010-10-10 05:36:26 -04:00 committed by Al Viro
parent 3049cfe24e
commit a4633357ac
1 changed files with 23 additions and 26 deletions
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49
fs/dcache.c
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@ -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 @@ repeat:
/* 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 @@ resume:
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);
}
/*