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authorYan, Zheng <zyan@redhat.com>2016-02-26 16:27:13 +0800
committerIlya Dryomov <idryomov@gmail.com>2016-03-25 18:51:53 +0100
commitaf5e5eb574776cdf1b756a27cc437bff257e22fe (patch)
treec96a1b12b10744491f89d19ac1bfe21f6a519747
parent89f081730c49a1d3b46359aa0054e6b3b80f47e4 (diff)
downloadlinux-af5e5eb574776cdf1b756a27cc437bff257e22fe.tar.bz2
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 <zyan@redhat.com>
-rw-r--r--fs/ceph/inode.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index cec68a6e20df..495decfc4b34 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) &&