ceph: choose readdir frag based on previous readdir reply
authorYan, Zheng <zyan@redhat.com>
Mon, 24 Apr 2017 03:56:50 +0000 (11:56 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 12 Jul 2017 14:53:54 +0000 (16:53 +0200)
commit8e7dedf725c6ebe3438972317e5a9bf3c905cd20
tree7cc703519f7e78e6f8141f2e76296f42e490b519
parent29f0189eb176b9dca0fbc8c0d70411fa0cb3fdb5
ceph: choose readdir frag based on previous readdir reply

commit b50c2de51e611da90cf3cf04c058f7e9bbe79e93 upstream.

The dirfragtree is lazily updated, it's not always accurate. Infinite
loops happens in following circumstance.

- client send request to read frag A
- frag A has been fragmented into frag B and C. So mds fills the reply
  with contents of frag B
- client wants to read next frag C. ceph_choose_frag(frag value of C)
  return frag A.

The fix is using previous readdir reply to calculate next readdir frag
when possible.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/ceph/dir.c