On Wed, 2010-08-18 at 22:57 +0300, Benny Halevy wrote:
> On Aug. 18, 2010, 21:07 +0300, Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> wrote:
> > On Wed, 2010-08-18 at 13:38 -0400, andros@xxxxxxxxxx wrote:
> >> From: Fred Isaman <iisaman@xxxxxxxxxxxxxx>
> >>
> >> clp->cl_exchange_flags is used both for client output and server input.
> >> This causes problems in certain recovery situations, when the server
> >> has sent back EXCHGID4_FLAG_CONFIRMED_R, causing the client to erroneously
> >> use the flag in future EXCHANGE_ID requests.
> >>
> >> Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxxxxxx>
> >> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
> >> ---
> >> fs/nfs/nfs4proc.c | 2 +-
> >> 1 files changed, 1 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> >> index 198d51d..e5fea95 100644
> >> --- a/fs/nfs/nfs4proc.c
> >> +++ b/fs/nfs/nfs4proc.c
> >> @@ -4427,7 +4427,7 @@ int nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred)
> >> nfs4_verifier verifier;
> >> struct nfs41_exchange_id_args args = {
> >> .client = clp,
> >> - .flags = clp->cl_exchange_flags,
> >> + .flags = clp->cl_exchange_flags & ~EXCHGID4_FLAG_CONFIRMED_R,
> >> };
> >> struct nfs41_exchange_id_res res = {
> >> .client = clp,
> >
> > Wait... This is utterly silly...
> >
> > So we start be passing in clp->cl_exchange_flags == 0, then the server
> > modifies that to some other value, and then from there on we always use
> > the latest value of clp->cl_exchange_flags that resulted from the last
> > call to EXCHANGE_ID????
> >
> > We should be setting .flags according to the client capabilities, not
> > according to the server reply...
> >
> > IOW:
> > args.flags = EXCHGID4_FLAG_SUPP_MOVED_REFER | EXCHGID4_FLAG_USE_NON_PNFS;
> >
> >
>
> Makes sense for upstream.
>
> For pNFS, besides dropping EXCHGID4_FLAG_USE_NON_PNFS we should retain
> EXCHGID4_FLAG_USE_PNFS_MDS | EXCHGID4_FLAG_USE_PNFS_DS as exchange_id
> is called from both the MDS and the DS paths.
No. As I read the spec, a pNFS-capable client should _retain_
EXCHGID4_FLAG_USE_NON_PNFS, and OR in the EXCHGID4_FLAG_USE_PNFS_MDS |
EXCHGID4_FLAG_USE_PNFS_DS flags too (see section 13.1).
The server will then reply with a subset of those 3 flags that tells the
client whether it is an MDS, a DS, or a non-MDS (or a valid combination
of 2 of those flags).
Trond
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