On Fri, 2022-07-15 at 18:42 +0000, Chuck Lever III wrote:

quoted

On Jul 15, 2022, at 2:32 PM, Jeff Layton [off-list ref] wrote:

v2:
- use nfsd_lookup_dentry instead of lookup_one_len

Here's a respin of the patches to fix up the potential race between an
open and delegation. I took Neil's advice an changed over to use
nfsd_lookup_dentry.

This patchset is based on top of Neil's recent patchset entitled:

   [PATCH 0/8] NFSD: clean up locking.

Thanks to both of you for pursuing this work! I think there are
some good improvements here.

Note that there are some outstanding review comments (aside from
the disagreement about how to refactor nfsd_create) so I expect
Neil will be reposting his series. This is just to note that, as
long as your series is based on his, I will consider your series
as RFC until his base series is stable and pulled.

I'll review again today or over the weekend.

Thanks. I think I'll be able to adapt this approach on top of whatever
Neil comes up with.

quoted

Tested with xfstests and it seemed to behave. I haven't done any testing
to ensure that the race is actually fixed, mainly because I don't have a
way to reliably reproduce it.

That's the thing: we don't have many tests that use multiple clients
targeting the same set of files.

Yeah, it's a difficult problem. Testing delegation behavior is
particularly difficult since the client doesn't have a lot of control
over them being granted in the first place.

quoted

Jeff Layton (2):
 nfsd: drop fh argument from alloc_init_deleg
 nfsd: vet the opened dentry after setting a delegation

fs/nfsd/nfs4state.c | 58 ++++++++++++++++++++++++++++++++++++++-------
1 file changed, 49 insertions(+), 9 deletions(-)

-- 
2.36.1

--
Chuck Lever

-- 
Jeff Layton [off-list ref]