On Wed, 2023-08-02 at 09:29 -0700, dai.ngo@xxxxxxxxxx wrote: > On 8/1/23 6:33 AM, Jeff Layton wrote: > > I noticed that xfstests generic/001 was failing against linux-next nfsd. > > > > The client would request a OPEN4_SHARE_ACCESS_WRITE open, and the server > > would hand out a write delegation. The client would then try to use that > > write delegation as the source stateid in a COPY > > not sure why the client opens the source file of a COPY operation with > OPEN4_SHARE_ACCESS_WRITE? > It doesn't. The original open is to write the data for the file being copied. It then opens the file again for READ, but since it has a write delegation, it doesn't need to talk to the server at all -- it can just use that stateid for later operations. > > or CLONE operation, and > > the server would respond with NFS4ERR_STALE. > > If the server does not allow client to use write delegation for the > READ, should the correct error return be NFS4ERR_OPENMODE? > The server must allow the client to use a write delegation for read operations. It's required by the spec, AFAIU. The error in this case was just bogus. The vfs copy routine would return -EBADF since the file didn't have FMODE_READ, and the nfs server would translate that into NFS4ERR_STALE. Probably there is a better v4 error code that we could translate EBADF to, but with this patch it shouldn't be a problem any longer. > > > > The problem is that the struct file associated with the delegation does > > not necessarily have read permissions. It's handing out a write > > delegation on what is effectively an O_WRONLY open. RFC 8881 states: > > > > "An OPEN_DELEGATE_WRITE delegation allows the client to handle, on its > > own, all opens." > > > > Given that the client didn't request any read permissions, and that nfsd > > didn't check for any, it seems wrong to give out a write delegation. > > > > Only hand out a write delegation if we have a O_RDWR descriptor > > available. If it fails to find an appropriate write descriptor, go > > ahead and try for a read delegation if NFS4_SHARE_ACCESS_READ was > > requested. > > > > This fixes xfstest generic/001. > > > > Closes: https://bugzilla.linux-nfs.org/show_bug.cgi?id=412 > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > --- > > Changes in v2: > > - Rework the logic when finding struct file for the delegation. The > > earlier patch might still have attached a O_WRONLY file to the deleg > > in some cases, and could still have handed out a write delegation on > > an O_WRONLY OPEN request in some cases. > > --- > > fs/nfsd/nfs4state.c | 29 ++++++++++++++++++----------- > > 1 file changed, 18 insertions(+), 11 deletions(-) > > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > index ef7118ebee00..e79d82fd05e7 100644 > > --- a/fs/nfsd/nfs4state.c > > +++ b/fs/nfsd/nfs4state.c > > @@ -5449,7 +5449,7 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, > > struct nfs4_file *fp = stp->st_stid.sc_file; > > struct nfs4_clnt_odstate *odstate = stp->st_clnt_odstate; > > struct nfs4_delegation *dp; > > - struct nfsd_file *nf; > > + struct nfsd_file *nf = NULL; > > struct file_lock *fl; > > u32 dl_type; > > > > @@ -5461,21 +5461,28 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp, > > if (fp->fi_had_conflict) > > return ERR_PTR(-EAGAIN); > > > > - if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) { > > - nf = find_writeable_file(fp); > > + /* > > + * Try for a write delegation first. We need an O_RDWR file > > + * since a write delegation allows the client to perform any open > > + * from its cache. > > + */ > > + if ((open->op_share_access & NFS4_SHARE_ACCESS_BOTH) == NFS4_SHARE_ACCESS_BOTH) { > > + nf = nfsd_file_get(fp->fi_fds[O_RDWR]); > > dl_type = NFS4_OPEN_DELEGATE_WRITE; > > - } else { > > Does this mean OPEN4_SHARE_ACCESS_WRITE do not get a write delegation? > It does not seem right. > > -Dai > Why? Per RFC 8881: "An OPEN_DELEGATE_WRITE delegation allows the client to handle, on its own, all opens." All opens. That includes read opens. An OPEN4_SHARE_ACCESS_WRITE open will succeed on a file to which the user has no read permissions. Therefore, we can't grant a write delegation since can't guarantee that the user is allowed to do that. > > + } > > + > > + /* > > + * If the file is being opened O_RDONLY or we couldn't get a O_RDWR > > + * file for some reason, then try for a read deleg instead. > > + */ > > + if (!nf && (open->op_share_access & NFS4_SHARE_ACCESS_READ)) { > > nf = find_readable_file(fp); > > dl_type = NFS4_OPEN_DELEGATE_READ; > > } > > - if (!nf) { > > - /* > > - * We probably could attempt another open and get a read > > - * delegation, but for now, don't bother until the > > - * client actually sends us one. > > - */ > > + > > + if (!nf) > > return ERR_PTR(-EAGAIN); > > - } > > + > > spin_lock(&state_lock); > > spin_lock(&fp->fi_lock); > > if (nfs4_delegation_exists(clp, fp)) > > > > --- > > base-commit: a734662572708cf062e974f659ae50c24fc1ad17 > > change-id: 20230731-wdeleg-bbdb6b25a3c6 > > > > Best regards, -- Jeff Layton <jlayton@xxxxxxxxxx>
