On Tue, 2021-04-06 at 19:04 +0100, Luis Henriques wrote: > On Tue, Apr 06, 2021 at 01:27:21PM -0400, Jeff Layton wrote: > <snip> > > > > > I've spent a few hours already looking at the bug I reported before, and I > > > > > can't really understand this code. What does it mean to increment > > > > > ->i_shared_gen at this point? > > > > > > > > > > The reason I'm asking is because it looks like the problem I'm seeing goes > > > > > away if I remove this code. Here's what I'm doing/seeing: > > > > > > > > > > # mount ... > > > > > # fscrypt unlock d > > > > > > > > > > -> 'd' dentry is eventually pruned at this point *if* ->i_shared_gen was > > > > > incremented by the line above. > > > > > > > > > > # cat d/f > > > > > > > > > > -> when ceph_fill_inode() is executed, 'd' isn't *not* set as encrypted > > > > > because both ci->i_xattrs.version and info->xattr_version are both > > > > > set to 0. > > > > > > > > > > > > > Interesting. That sounds like it might be the bug right there. "d" > > > > should clearly have a fscrypt context in its xattrs at that point. If > > > > the MDS isn't passing that back, then that could be a problem. > > > > > > > > I had a concern about that when I was developing this, and I *thought* > > > > Zheng had assured us that the MDS will always pass along the xattr blob > > > > in a trace. Maybe that's not correct? > > > > > > Hmm, that's what I thought too. I was hoping not having to go look at the > > > MDS, but seems like I'll have to :-) > > > > > > > That'd be good, if possible. > > > > > > > cat: d/f: No such file or directory > > > > > > > > > > I'm not sure anymore if the issue is on the client or on the MDS side. > > > > > Before digging deeper, I wonder if this ring any bell. ;-) > > > > > > > > > > > > > > > > > > No, this is not something I've seen before. > > > > > > > > Dentries that live in a directory have a copy of the i_shared_gen of the > > > > directory when they are instantiated. Bumping that value on a directory > > > > should basically ensure that its child dentries end up invalidated, > > > > which is what we want once we add the key to the directory. Once we add > > > > a key, any old dentries in that directory are no longer valid. > > > > > > > > That said, I could certainly have missed some subtlety here. > > > > > > Great, thanks for clarifying. This should help me investigate a little > > > bit more. > > > > > > [ And I'm also surprised you don't see this behaviour as it's very easy to > > > reproduce. ] > > > > > > > > > > It is odd... fwiw, I ran this for 5 mins or so and never saw a problem: > > > > $ while [ $? -eq 0 ]; do sudo umount /mnt/crypt; sudo mount /mnt/crypt; fscrypt unlock --key=/home/jlayton/fscrypt-keyfile /mnt/crypt/d; cat /mnt/crypt/d/f; done > > > > TBH I only do this operation once and it almost always fails. The only > difference I see is that I don't really use a keyfile, but a passphrase > instead. Not sure if it makes any difference. Also, it may be worth > adding a delay before the 'cat' to make sure the dentry is pruned. > No joy. I tried different delays between 1-5s and it didn't change anything. > > ...do I need some other operations in between? Also, the cluster in this > > case is Pacific. It's possible this is a result of changes since then if > > you're on a vstart cluster or something. > > > > $ sudo ./cephadm version > > Using recent ceph image docker.io/ceph/ceph@sha256:9b04c0f15704c49591640a37c7adfd40ffad0a4b42fecb950c3407687cb4f29a > > ceph version 16.2.0 (0c2054e95bcd9b30fdd908a79ac1d8bbc3394442) pacific (stable) > > I've re-compiled the cluster after hard-resetting it to commit > 6a19e303187c which you mentioned in a previous email in this thread. But > the result was the same. > > Anyway, using a vstart cluster is also a huge difference I guess. I'll > keep debugging. Thanks! > I may try to set one up today to see if I can reproduce it. Thanks for the testing help so far! -- Jeff Layton <jlayton@xxxxxxxxxx>
