Commit a4633357 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
Browse files

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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3049cfe2

fs/dcache.c

+23 −26
Original line number Diff line number Diff line
@@ -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)

{

	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_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);

}



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);

	}

}
@@ -253,7 +250,6 @@ 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);



 	spin_unlock(&dentry->d_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);

		}



		/*

CRA Git | Maintained and supported by SUSTech CRA and CCSE