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Commit af5e5eb5 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: fix race during filling readdir cache 



Readdir cache uses page cache to save dentry pointers. When adding
dentry pointers to middle of a page, we need to make sure the page
already exists. Otherwise the beginning part of the page will be
invalid pointers.

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent 89f08173

fs/ceph/inode.c

+7 −2
Original line number Diff line number Diff line
@@ -1349,15 +1349,20 @@ static int fill_readdir_cache(struct inode *dir, struct dentry *dn, 


	if (!ctl->page || pgoff != page_index(ctl->page)) {

		ceph_readdir_cache_release(ctl);

		if (idx == 0)

			ctl->page = grab_cache_page(&dir->i_data, pgoff);

		else

			ctl->page = find_lock_page(&dir->i_data, pgoff);

		if (!ctl->page) {

			ctl->index = -1;

			return -ENOMEM;

			return idx == 0 ? -ENOMEM : 0;

		}

		/* reading/filling the cache are serialized by

		 * i_mutex, no need to use page lock */

		unlock_page(ctl->page);

		ctl->dentries = kmap(ctl->page);

		if (idx == 0)

			memset(ctl->dentries, 0, PAGE_CACHE_SIZE);

	}



	if (req->r_dir_release_cnt == atomic64_read(&ci->i_release_count) &&