Hi Trond, This patch set produces the following in my testing. Basically what I see the client is prevented from using a delegation at all. After I induce a race of DELEGRETURN/OPEN --- the racing OPEN gets a delegation (it returns the same seqid and other as the delegation being returned) but the client doesn't use it. --- the following (next) OPEN that also gets a delegation immediately has the client returning the given delegation. Disclaimer: in my testing the racing DELEGRETURN doesn't fail with OLD_STATEID, NetApp returns OK. On Thu, Oct 24, 2019 at 6:56 AM Trond Myklebust <trondmy@xxxxxxxxx> wrote: > > The following patchset fixes up a number of issues with delegations, > but mainly attempts to fix a race condition between open and > delegreturn, where the open and the delegreturn get re-ordered so > that the delegreturn ends up revoking the delegation that was returned > by the open. > The root cause is that in certain circumstances, we may currently end > up freeing the delegation from delegreturn, so when we later receive > the reply to the open, we've lost track of the fact that the seqid > predates the one that was returned. > > This patchset fixes that case by ensuring that we always keep track > of the last delegation stateid that was returned for any given inode. > That way, if we later see a delegation stateid with the same opaque > field, but an older seqid, we know we cannot trust it, and so we > ask to replay the OPEN compound. > > Trond Myklebust (14): > NFSv4: Don't allow a cached open with a revoked delegation > NFSv4: Fix delegation handling in update_open_stateid() > NFSv4: nfs4_callback_getattr() should ignore revoked delegations > NFSv4: Delegation recalls should not find revoked delegations > NFSv4: fail nfs4_refresh_delegation_stateid() when the delegation was > revoked > NFS: Rename nfs_inode_return_delegation_noreclaim() > NFSv4: Don't remove the delegation from the super_list more than once > NFSv4: Hold the delegation spinlock when updating the seqid > NFSv4: Clear the NFS_DELEGATION_REVOKED flag in > nfs_update_inplace_delegation() > NFSv4: Update the stateid seqid in nfs_revoke_delegation() > NFSv4: Revoke the delegation on success in nfs4_delegreturn_done() > NFSv4: Ignore requests to return the delegation if it was revoked > NFSv4: Don't reclaim delegations that have been returned or revoked > NFSv4: Fix races between open and delegreturn > > fs/nfs/callback_proc.c | 2 +- > fs/nfs/delegation.c | 109 +++++++++++++++++++++++++++++------------ > fs/nfs/delegation.h | 4 +- > fs/nfs/nfs4proc.c | 13 ++--- > fs/nfs/nfs4super.c | 4 +- > 5 files changed, 88 insertions(+), 44 deletions(-) > > -- > 2.21.0 >
