On Wed, 2024-02-07 at 14:58 -0500, Olga Kornievskaia wrote: > On Wed, Feb 7, 2024 at 2:51 PM Olga Kornievskaia > <olga.kornievskaia@xxxxxxxxx> wrote: > > > > On Wed, Feb 7, 2024 at 2:12 PM Trond Myklebust > > <trondmy@xxxxxxxxxxxxxxx> wrote: > > > > > > On Wed, 2024-02-07 at 13:29 -0500, Olga Kornievskaia wrote: > > > > From: Olga Kornievskaia <kolga@xxxxxxxxxx> > > > > > > > > Currently, if the server returns a partial layout, the client > > > > gets > > > > stuck asking for a layout indefinitely. Until we add support > > > > for > > > > partial layouts, treat partial layout as layout unavailable > > > > error. > > > > > > > > Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx> > > > > --- > > > > fs/nfs/nfs4proc.c | 6 ++++++ > > > > 1 file changed, 6 insertions(+) > > > > > > > > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > > > > index dae4c1b6cc1c..108bc7f3e8c2 100644 > > > > --- a/fs/nfs/nfs4proc.c > > > > +++ b/fs/nfs/nfs4proc.c > > > > @@ -9790,6 +9790,12 @@ nfs4_proc_layoutget(struct > > > > nfs4_layoutget > > > > *lgp, > > > > if (status != 0) > > > > goto out; > > > > > > > > + /* Since client does not support partial pnfs layout, > > > > then > > > > treat > > > > + * getting a partial layout as LAYOUTUNAVAILABLE error > > > > + */ > > > > + if (lgp->args.range.length != lgp->res.range.length) > > > > + task->tk_status = -NFS4ERR_LAYOUTUNAVAILABLE; > > > > > > > > > I think this case is better handled by allowing the caller to set > > > lgp- > > > > args.minlength to an appropriate minimum value. > > > > I do not understand what this suggestion means. What I can think of > > is > > that the caller would set an appropriate minimum value and the code > > here would check that the result is at least as large? > > A follow up question on a "minimum value". It seems that since the > client would then need to set it to the same value as the "length" > (ie > whole file layout value), yes? So it shifts the responsibility to the > server, disallowing it from returning a partial layout. My expectation is that we use 'minimum length' to mean the length that is the smallest value that is acceptable to the client (i.e. the "loga_minlength" as described in RFC5661 Section 18.43). If the client cannot handle a layout that is smaller than a whole file layout, then that's the value we should set for loga_minlength. The server then gets to decide if it can honour the request, or should return NFS4ERR_LAYOUTTRYLATER. The other value is the desired length (i.e. the "loga_length" as described in RFC5661, Section 18.43). Currently, in the flexfiles client, we set that to the length of the I/O request that we're trying to obey. If the server can meet or exceed that value, it will still do so, but it doesn't need to return an error if it cannot meet that value provided that it can still return a layout with a length that meets the "loga_minlength" requirement. -- Trond Myklebust Linux NFS client maintainer, Hammerspace trond.myklebust@xxxxxxxxxxxxxxx
