From: Yan, Zheng <zyan@redhat.com>
Date: Wed, 12 Oct 2016 06:48:28 +0000 (+0800)
Subject: ceph: fix readdir vs fragmentation race
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f72f94555aa32b2c4374dde5ad9b960cc4ff32e2;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

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 bca1b49c1c4b..ef4d04647325 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);