| Message ID | 20140409152055.GB22938@fieldses.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Apr 9, 2014, at 11:20, Dr Fields James Bruce <bfields@fieldses.org> wrote: > On Wed, Apr 09, 2014 at 10:12:58AM -0400, Trond Myklebust wrote: >> >> On Apr 9, 2014, at 9:56, Dr Fields James Bruce <bfields@fieldses.org> wrote: >> >>> On Wed, Apr 09, 2014 at 09:41:28AM -0400, Trond Myklebust wrote: >>>> According to RFC5661, NFS4ERR_REP_TOO_BIG/NFS4ERR_REP_TOO_BIG_TO_CACHE >>>> are only appropriate if "The reply to a Compound would exceed the >>>> channel's negotiated maximum response size.”. Given that the callers >>>> of nfsd4_encode_fattr appear to all pass in ‘buffer’ and ‘buflen’ >>>> arguments that are limited to single page, doesn’t this mean that you >>>> can end up returning nfs4err_resource in cases where >>>> nfserr_rep_too_big/nfserr_rep_too_big_to_cache are simply not >>>> appropriate? >>> >>> Yes, you're right. This will be fixed by later patches which remove >>> those arbitrary single-page limits, but for now it's a bug. >>> >>> This was probably a bad way to sequence those patches. >>> >>> That said, all that patch is doing in those cases is replacing one >>> useless error by another, so in practice I don't think reverting the >>> patch would help anyone--so I'm inclined to leave this alone and wait >>> for the real bug to be fixed (which is that we're imposing limits other >>> than the session limits). >>> >>> Is this causing some problem right now? >>> >> >> I’m not aware of any bug reports yet, but I did want to make sure that it was on your radar. >> >> That said, one immediate consequence of this patch will be that NFSv4.1 clients will now report EIO instead of EREMOTEIO if they hit the problem. That may make debugging a little less obvious. >> Another consequence will be that if we ever do try to add client side handling of NFS4ERR_REP_TOO_BIG, then we now have to deal with the “handle existing buggy server” syndrome. > > Yeah, OK, I can see it would be annoying; maybe it's worth something > like the following for 3.15? > > And then for 3.16 I'll delay this change till later in the xdr-encoding > series. On balance, that might be preferable… Cheers Trond > --b. > > commit a675223424673a6393fd291280af51fddd6a97ec > Author: J. Bruce Fields <bfields@redhat.com> > Date: Wed Apr 9 11:07:01 2014 -0400 > > Revert "nfsd4: fix nfs4err_resource in 4.1 case" > > Since we're still limiting attributes to a page, the result here is that > a large getattr result will return NFS4ERR_REP_TOO_BIG/TOO_BIG_TO_CACHE > instead of NFS4ERR_RESOURCE. > > Both error returns are wrong, and the real bug here is the arbitrary > limit on getattr results, fixed by as-yet out-of-tree patches. But at a > minimum we can make life easier for clients by sticking to one broken > behavior in released kernels instead of two.... > > Trond says: > > one immediate consequence of this patch will be that NFSv4.1 > clients will now report EIO instead of EREMOTEIO if they hit the > problem. That may make debugging a little less obvious. > > Another consequence will be that if we ever do try to add client > side handling of NFS4ERR_REP_TOO_BIG, then we now have to deal > with the “handle existing buggy server” syndrome. > > Reported-by: Trond Myklebust <trond.myklebust@primarydata.com> > Signed-off-by: J. Bruce Fields <bfields@redhat.com> > > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c > index 2723c1b..18881f3 100644 > --- a/fs/nfsd/nfs4xdr.c > +++ b/fs/nfsd/nfs4xdr.c > @@ -3627,14 +3627,6 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op) > /* nfsd4_check_resp_size guarantees enough room for error status */ > if (!op->status) > op->status = nfsd4_check_resp_size(resp, 0); > - if (op->status == nfserr_resource && nfsd4_has_session(&resp->cstate)) { > - struct nfsd4_slot *slot = resp->cstate.slot; > - > - if (slot->sl_flags & NFSD4_SLOT_CACHETHIS) > - op->status = nfserr_rep_too_big_to_cache; > - else > - op->status = nfserr_rep_too_big; > - } > if (so) { > so->so_replay.rp_status = op->status; > so->so_replay.rp_buflen = (char *)resp->p - (char *)(statp+1);
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 2723c1b..18881f3 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -3627,14 +3627,6 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op) /* nfsd4_check_resp_size guarantees enough room for error status */ if (!op->status) op->status = nfsd4_check_resp_size(resp, 0); - if (op->status == nfserr_resource && nfsd4_has_session(&resp->cstate)) { - struct nfsd4_slot *slot = resp->cstate.slot; - - if (slot->sl_flags & NFSD4_SLOT_CACHETHIS) - op->status = nfserr_rep_too_big_to_cache; - else - op->status = nfserr_rep_too_big; - } if (so) { so->so_replay.rp_status = op->status; so->so_replay.rp_buflen = (char *)resp->p - (char *)(statp+1);