switch shrink_dcache_for_umount() to use of d_walk() (42c32608) · Commits · e / devices / android_kernel_oneplus_sm7250

fs/dcache.c

+85 −110

Original line number	Diff line number	Diff line
		@@ -1074,116 +1074,6 @@ void shrink_dcache_sb(struct super_block *sb)
		}
		EXPORT_SYMBOL(shrink_dcache_sb);

		/*
		* destroy a single subtree of dentries for unmount
		* - see the comments on shrink_dcache_for_umount() for a description of the
		* locking
		*/
		static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
		{
		struct dentry *parent;

		BUG_ON(!IS_ROOT(dentry));

		for (;;) {
		/* descend to the first leaf in the current subtree */
		while (!list_empty(&dentry->d_subdirs))
		dentry = list_entry(dentry->d_subdirs.next,
		struct dentry, d_u.d_child);

		/* consume the dentries from this leaf up through its parents
		* until we find one with children or run out altogether */
		do {
		struct inode *inode;

		/*
		* inform the fs that this dentry is about to be
		* unhashed and destroyed.
		*/
		if ((dentry->d_flags & DCACHE_OP_PRUNE) &&
		!d_unhashed(dentry))
		dentry->d_op->d_prune(dentry);

		dentry_lru_del(dentry);
		__d_shrink(dentry);

		if (dentry->d_lockref.count != 0) {
		printk(KERN_ERR
		"BUG: Dentry %p{i=%lx,n=%s}"
		" still in use (%d)"
		" [unmount of %s %s]\n",
		dentry,
		dentry->d_inode ?
		dentry->d_inode->i_ino : 0UL,
		dentry->d_name.name,
		dentry->d_lockref.count,
		dentry->d_sb->s_type->name,
		dentry->d_sb->s_id);
		BUG();
		}

		if (IS_ROOT(dentry)) {
		parent = NULL;
		list_del(&dentry->d_u.d_child);
		} else {
		parent = dentry->d_parent;
		parent->d_lockref.count--;
		list_del(&dentry->d_u.d_child);
		}

		inode = dentry->d_inode;
		if (inode) {
		dentry->d_inode = NULL;
		hlist_del_init(&dentry->d_alias);
		if (dentry->d_op && dentry->d_op->d_iput)
		dentry->d_op->d_iput(dentry, inode);
		else
		iput(inode);
		}

		d_free(dentry);

		/* finished when we fall off the top of the tree,
		* otherwise we ascend to the parent and move to the
		* next sibling if there is one */
		if (!parent)
		return;
		dentry = parent;
		} while (list_empty(&dentry->d_subdirs));

		dentry = list_entry(dentry->d_subdirs.next,
		struct dentry, d_u.d_child);
		}
		}

		/*
		* destroy the dentries attached to a superblock on unmounting
		* - we don't need to use dentry->d_lock because:
		* - the superblock is detached from all mountings and open files, so the
		* dentry trees will not be rearranged by the VFS
		* - s_umount is write-locked, so the memory pressure shrinker will ignore
		* any dentries belonging to this superblock that it comes across
		* - the filesystem itself is no longer permitted to rearrange the dentries
		* in this superblock
		*/
		void shrink_dcache_for_umount(struct super_block *sb)
		{
		struct dentry *dentry;

		if (down_read_trylock(&sb->s_umount))
		BUG();

		dentry = sb->s_root;
		sb->s_root = NULL;
		dentry->d_lockref.count--;
		shrink_dcache_for_umount_subtree(dentry);

		while (!hlist_bl_empty(&sb->s_anon)) {
		dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);
		shrink_dcache_for_umount_subtree(dentry);
		}
		}

		/*
		* This tries to ascend one level of parenthood, but
		* we can race with renaming, so we need to re-check
		@@ -1478,6 +1368,91 @@ void shrink_dcache_parent(struct dentry *parent)
		}
		EXPORT_SYMBOL(shrink_dcache_parent);

		static enum d_walk_ret umount_collect(void _data, struct dentry dentry)
		{
		struct select_data *data = _data;
		enum d_walk_ret ret = D_WALK_CONTINUE;

		if (dentry->d_lockref.count) {
		dentry_lru_del(dentry);
		if (likely(!list_empty(&dentry->d_subdirs)))
		goto out;
		if (dentry == data->start && dentry->d_lockref.count == 1)
		goto out;
		printk(KERN_ERR
		"BUG: Dentry %p{i=%lx,n=%s}"
		" still in use (%d)"
		" [unmount of %s %s]\n",
		dentry,
		dentry->d_inode ?
		dentry->d_inode->i_ino : 0UL,
		dentry->d_name.name,
		dentry->d_lockref.count,
		dentry->d_sb->s_type->name,
		dentry->d_sb->s_id);
		BUG();
		} else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
		/*
		* We can't use d_lru_shrink_move() because we
		* need to get the global LRU lock and do the
		* LRU accounting.
		*/
		if (dentry->d_flags & DCACHE_LRU_LIST)
		d_lru_del(dentry);
		d_shrink_add(dentry, &data->dispose);
		data->found++;
		ret = D_WALK_NORETRY;
		}
		out:
		if (data->found && need_resched())
		ret = D_WALK_QUIT;
		return ret;
		}

		/*
		* destroy the dentries attached to a superblock on unmounting
		*/
		void shrink_dcache_for_umount(struct super_block *sb)
		{
		struct dentry *dentry;

		if (down_read_trylock(&sb->s_umount))
		BUG();

		dentry = sb->s_root;
		sb->s_root = NULL;
		for (;;) {
		struct select_data data;

		INIT_LIST_HEAD(&data.dispose);
		data.start = dentry;
		data.found = 0;

		d_walk(dentry, &data, umount_collect, NULL);
		if (!data.found)
		break;

		shrink_dentry_list(&data.dispose);
		cond_resched();
		}
		d_drop(dentry);
		dput(dentry);

		while (!hlist_bl_empty(&sb->s_anon)) {
		struct select_data data;
		dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash);

		INIT_LIST_HEAD(&data.dispose);
		data.start = NULL;
		data.found = 0;

		d_walk(dentry, &data, umount_collect, NULL);
		if (data.found)
		shrink_dentry_list(&data.dispose);
		cond_resched();
		}
		}

		static enum d_walk_ret check_and_collect(void _data, struct dentry dentry)
		{
		struct select_data *data = _data;