On 29 May 2019, at 12:21, Trond Myklebust wrote: > On Wed, 2019-05-29 at 11:08 -0400, Benjamin Coddington wrote: >> Hey, here's an interesting one, this seems wrong: >> >> [root@fedora27_c2_v5 ~]# mkdir /mnt/one >> [root@fedora27_c2_v5 ~]# mkdir /mnt/two >> [root@fedora27_c2_v5 ~]# mount -t nfs -ov4,noac,sec=sys,nosharecache >> 192.168.122.50:/exports /mnt/one >> [root@fedora27_c2_v5 ~]# mount -t nfs -ov4,noac,sec=sys,nosharecache >> 192.168.122.50:/exports /mnt/two >> [root@fedora27_c2_v5 ~]# mkdir /mnt/one/A >> [root@fedora27_c2_v5 ~]# mkdir /mnt/one/B >> [root@fedora27_c2_v5 ~]# touch /mnt/one/A/foo >> [root@fedora27_c2_v5 ~]# cat /mnt/two/A/foo >> [root@fedora27_c2_v5 ~]# mv /mnt/two/A/foo /mnt/two/B/foo >> [root@fedora27_c2_v5 ~]# mv /mnt/one/B/foo /mnt/one/A/foo >> [root@fedora27_c2_v5 ~]# cat /mnt/two/A/foo >> [root@fedora27_c2_v5 ~]# stat /mnt/two/B/foo >> File: /mnt/two/B/foo >> Size: 0 Blocks: 0 IO Block: 262144 regular >> empty >> file >> Device: 2fh/47d Inode: 439603 Links: 1 >> Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: >> ( 0/ root) >> Context: system_u:object_r:nfs_t:s0 >> Access: 2019-05-28 14:00:18.929663705 -0400 >> Modify: 2019-05-28 14:00:18.929663705 -0400 >> Change: 2019-05-28 14:00:58.990124573 -0400 >> Birth: - >> >> >> ^^ that lstat should return -ENOENT. >> >> I think we detect a stale directory by comparing the directory's >> change_attr with the dentry's d_time. But, here's a case where they >> are >> the same! >> >> Am I wrong about this, or any clever ideas to catch this case? >> > > When you are mounting using 'nosharecache' then you are making /mnt/one > and /mnt/two act as if they are different filesystems. The fact that > they are the same on the server, means you are setting up a testcase > where the files+directories are acting like the "changing on the > server" case as far as the client is concerned. > > If you want the above to work in a sane fashion, then just don't use > 'nosharecache'. That was deliberate to avoid having to show two clients in the example.. sorry, I should have been more explicit. I think the client should be able to detect this case, since it can see an updated change_attr for that particular directory -- that is "/mnt/two/B/foo", but maybe it needs to compare the change_attr to its previous value instead of comparing it to the child's d_time? The person who reported it has some workload that flips files between directories on separate clients, and doesn't like it when `mv` reports "source and destination are the same file". Ben
