On Wed, Feb 7, 2024 at 3:42 PM Trond Myklebust <trondmy@xxxxxxxxxxxxxxx> wrote: > > 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. I think I'm misunderstanding a partial layout and the client's ability to support them. Is partial layout support something that generic pnfs code does or is that something that each layout driver supposed to support? I was under the impression that it is or will be generic. I'm specifically confused because in the previous email you said, the minimal (layout) length is set to a PAGE (or I/O request size) and that each driver is supposed to be able to handle that. That seems to imply to me that if the server returned back a layout of 1 page (which is a partial layout) then the layoutdriver should be OK with it (mean handle partial layouts) (which filalyout driver does not, it needs a whole file layout), is that correct? > > -- > Trond Myklebust > Linux NFS client maintainer, Hammerspace > trond.myklebust@xxxxxxxxxxxxxxx > >
