[PATCH 4/5] VFS: Add shrink_pagecache_parent

[Li Wang <liwang@ubuntukylin.com>]

Analogous to shrink_dcache_parent except that it collects inodes.
It is not very appropriate to be put in dcache.c, but d_walk can only
be invoked from here.

Signed-off-by: Li Wang <liwang@ubuntukylin.com>
Signed-off-by: Yunchuan Wen <yunchuanwen@ubuntukylin.com>
---
 fs/dcache.c |   35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 4bdb300..bcbfd0d 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1318,6 +1318,41 @@ void shrink_dcache_parent(struct dentry *parent)
 }
 EXPORT_SYMBOL(shrink_dcache_parent);
 
+static enum d_walk_ret gather_inode(void *data, struct dentry *dentry)
+{
+	struct list_head *list = data;
+	struct inode *inode = dentry->d_inode;
+
+	if (inode == NULL)
+		goto out;
+	spin_lock(&inode->i_lock);
+	if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
+	(inode->i_mapping->nrpages == 0) ||
+		(!list_empty(&inode->i_lru))) {
+		goto out_unlock;
+	}
+	__iget(inode);
+	list_add_tail(&inode->i_lru, list);
+out_unlock:
+	spin_unlock(&inode->i_lock);
+out:
+	return D_WALK_CONTINUE;
+}
+
+void shrink_pagecache_parent(struct dentry *parent)
+{
+	LIST_HEAD(list);
+	struct inode *inode, *next;
+
+	d_walk(parent, &list, gather_inode, NULL);
+	list_for_each_entry_safe(inode, next, &list, i_lru) {
+		list_del_init(&inode->i_lru);
+		invalidate_mapping_pages(inode->i_mapping, 0, -1);
+		iput(inode);
+	}
+}
+EXPORT_SYMBOL(shrink_pagecache_parent);
+
 static enum d_walk_ret umount_collect(void *_data, struct dentry *dentry)
 {
 	struct select_data *data = _data;
-- 
1.7.9.5

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