From af5e5eb574776cdf1b756a27cc437bff257e22fe Mon Sep 17 00:00:00 2001 From: "Yan, Zheng" Date: Fri, 26 Feb 2016 16:27:13 +0800 Subject: [PATCH] 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: Yan, Zheng --- fs/ceph/inode.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c index cec68a6..495decf 100644 --- a/fs/ceph/inode.c +++ b/fs/ceph/inode.c @@ -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); - ctl->page = grab_cache_page(&dir->i_data, pgoff); + 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) && -- 2.7.4