diff options
authorYan, Zheng <>2017-07-06 11:12:21 +0800
committerGreg Kroah-Hartman <>2017-07-27 15:08:07 -0700
commitacccf01a807abddda5ceb2fe3b72a38429044d0e (patch)
parentd42f9c7435c06c370966281782fd0e33a2eff460 (diff)
ceph: fix race in concurrent readdir
commit 84583cfb973c4313955c6231cc9cb3772d280b15 upstream. For a large directory, program needs to issue multiple readdir syscalls to get all dentries. When there are multiple programs read the directory concurrently. Following sequence of events can happen. - program calls readdir with pos = 2. ceph sends readdir request to mds. The reply contains N1 entries. ceph adds these N1 entries to readdir cache. - program calls readdir with pos = N1+2. The readdir is satisfied by the readdir cache, N2 entries are returned. (Other program calls readdir in the middle, which fills the cache) - program calls readdir with pos = N1+N2+2. ceph sends readdir request to mds. The reply contains N3 entries and it reaches directory end. ceph adds these N3 entries to the readdir cache and marks directory complete. The second readdir call does not update fi->readdir_cache_idx. ceph add the last N3 entries to wrong places. Signed-off-by: "Yan, Zheng" <> Signed-off-by: Ilya Dryomov <> Signed-off-by: Greg Kroah-Hartman <>
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index aca0d884de73..cec25691cbae 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -292,6 +292,11 @@ out:
if (ret < 0)
err = ret;
+ /* last_name no longer match cache index */
+ if (fi->readdir_cache_idx >= 0) {
+ fi->readdir_cache_idx = -1;
+ fi->dir_release_count = 0;
+ }
return err;