fold try_prune_one_dentry() (5c47e6d0) · Commits · e / devices / android_kernel_fairphone_FP3

fs/dcache.c

+25 −50

Original line number	Diff line number	Diff line
		@@ -787,47 +787,9 @@ void d_prune_aliases(struct inode *inode)
		}
		EXPORT_SYMBOL(d_prune_aliases);

		/*
		* Try to throw away a dentry - free the inode, dput the parent.
		* Requires dentry->d_lock is held, and dentry->d_count == 0.
		* Releases dentry->d_lock.
		*
		* This may fail if locks cannot be acquired no problem, just try again.
		*/
		static struct dentry * try_prune_one_dentry(struct dentry *dentry)
		__releases(dentry->d_lock)
		{
		struct dentry *parent;

		parent = dentry_kill(dentry, 0);
		/*
		* If dentry_kill returns NULL, we have nothing more to do.
		* if it returns the same dentry, trylocks failed. In either
		* case, just loop again.
		*
		* Otherwise, 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.
		*/
		if (!parent)
		return NULL;
		if (parent == dentry)
		return dentry;

		/* Prune ancestors. */
		dentry = parent;
		while (dentry) {
		if (lockref_put_or_lock(&dentry->d_lockref))
		return NULL;
		dentry = dentry_kill(dentry, 1);
		}
		return NULL;
		}

		static void shrink_dentry_list(struct list_head *list)
		{
		struct dentry *dentry;
		struct dentry dentry, parent;

		rcu_read_lock();
		for (;;) {
		@@ -863,22 +825,35 @@ static void shrink_dentry_list(struct list_head *list)
		}
		rcu_read_unlock();

		parent = dentry_kill(dentry, 0);
		/*
		* If 'try_to_prune()' returns a dentry, it will
		* be the same one we passed in, and d_lock will
		* have been held the whole time, so it will not
		* have been added to any other lists. We failed
		* to get the inode lock.
		*
		* We just add it back to the shrink list.
		* If dentry_kill returns NULL, we have nothing more to do.
		*/
		if (!parent) {
		rcu_read_lock();
		continue;
		}
		if (unlikely(parent == dentry)) {
		/*
		* trylocks have failed and d_lock has been held the
		* whole time, so it could not have been added to any
		* other lists. Just add it back to the shrink list.
		*/
		dentry = try_prune_one_dentry(dentry);

		rcu_read_lock();
		if (dentry) {
		d_shrink_add(dentry, list);
		spin_unlock(&dentry->d_lock);
		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, 1);
		rcu_read_lock();
		}
		rcu_read_unlock();
		}