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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>
This commit is contained in:
Yan, Zheng 2016-10-12 14:48:28 +08:00 committed by Ilya Dryomov
parent 0d7718f666
commit f72f94555a
1 changed files with 2 additions and 1 deletions
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3
fs/ceph/inode.c
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@ -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);