ceph: fix readdir vs fragmentation race
following sequence of events tigger the race
- client readdir frag 0* -> got item 'A'
- MDS merges frag 0* and frag 1*
- client send readdir request (frag 1*, offset 2, readdir_start 'A')
- MDS reply items (that are after item 'A') in frag *
Link: http://tracker.ceph.com/issues/17286
Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index bca1b49..ef4d046 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1511,7 +1511,8 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
ceph_fill_dirfrag(d_inode(parent), rinfo->dir_dir);
}
- if (ceph_frag_is_leftmost(frag) && req->r_readdir_offset == 2) {
+ if (ceph_frag_is_leftmost(frag) && req->r_readdir_offset == 2 &&
+ !(rinfo->hash_order && req->r_path2)) {
/* note dir version at start of readdir so we can tell
* if any dentries get dropped */
req->r_dir_release_cnt = atomic64_read(&ci->i_release_count);
